A fish ladder is a structure that allows migrating fish passage over or around an obstacle on a river

The survival of many fish species depends on migrations up and down rivers. Among anadromous fish such as salmon, shad, and sturgeon, downstream migration is a feature of early life stages, while upstream migration is a feature of adult life. Among catadromous, like the North American eel, the opposite is true. River obstructions such as dams, culverts, and waterfalls have the potential to slow or stop fish migration. Indeed, these impediments to fish migration are often implicated in the decline of certain fish stocks.

Bivalves even make their own shells. An internal organ called the mantle secretes calcium carbonate so that as the inner invertebrate grows, the outer shell provides a roomier home.

A fish ladder, also known as a fishway, provides a detour route for migrating fish past a particular obstruction on the river. Designs vary depending on the obstruction, river flow, and species of fish affected, but the general principle is the same for all fish ladders: the ladder contains a series of ascending pools that are reached by swimming against a stream of water. Fish leap through the cascade of rushing water, rest in a pool, and then repeat the process until they are out of the ladder.

Bivalve mollusks (e.g., clams, oysters, mussels, scallops) have an external covering that is a two-part hinged shell that contains a soft-bodied invertebrate

Like fish, bivalve mollusks breathe through their gills. As filter feeders, bivalves gather food through their gills. Some bivalves have a pointed, retractable "foot" that protrudes from the shell and digs into the surrounding sediment, effectively enabling the creature to move or burrow.

Bivalves even make their own shells. An internal organ called the mantle secretes calcium carbonate so that as the inner invertebrate grows, the outer shell provides a roomier home.

Many bivalve species play important roles in aquatic and marine ecosystems by filtering the water and serving as habitat and prey for a variety of sea life. This diverse group of species, estimated at about 9,200, inhabits virtually the entire world ocean, from the balmy tropics to the sub-zero Arctic, and from the deep ocean to sandy and rocky shorelines. A few have even taken up residence around hydrothermal vents found deep in the Pacific Ocean, below 13,000 feet.

If the bivalve's biological brilliance alone fails to impress, then consider that NOAA estimated the 2011 economic value of commercial bivalve mollusk harvesting at about $1 billion annually in the U.S., and the weight of the harvest was estimated at 153.6 million pounds.

For more information:
Sunflower sea star, National Marine Fisheries Service
Six-rayed sea star, National Marine Fisheries Service

Ocean acidification refers to a reduction in the pH of the ocean over an extended period time, caused primarily by uptake of carbon dioxide (CO2) from the atmosphere.

For more than 200 years, or since the industrial revolution, the concentration of carbon dioxide (CO2) in the atmosphere has increased due to the burning of fossil fuels and land use change. The ocean absorbs about 30 percent of the CO2 that is released in the atmosphere, and as levels of atmospheric CO2 increase, so do the levels in the ocean.

When CO2 is absorbed by seawater, a series of chemical reactions occur resulting in the increased concentration of hydrogen ions. This increase causes the seawater to become more acidic and causes carbonate ions to be relatively less abundant.

Carbonate ions are an important building block of structures such as sea shells and coral skeletons. Decreases in carbonate ions can make building and maintaining shells and other calcium carbonate structures difficult for calcifying organisms such as oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton.

These changes in ocean chemistry can affect the behavior of non-calcifying organisms as well. Certain fish’s ability to detect predators is decreased in more acidic waters. When these organisms are at risk, the entire food web may also be at risk.

Ocean acidification is affecting the entire world’s oceans, including coastal estuaries and waterways. Many economies are dependent on fish and shellfish and people worldwide rely on food from the ocean as their primary source of protein.

PBDEs, or polybrominated diphenyl ethers, are a class of fire retardant chemicals

PBDEs are found in a variety of consumer products, from TVs and toasters to mattresses and drapes. These chemicals are intended to slow the rate of ignition and fire growth, allowing people more time to escape from a fire or extinguish it. In recent years, PBDEs have generated international concern over their widespread distribution in the environment, their potential to bioaccumulate in humans and wildlife, and their suspected adverse human health effects. In the U.S., PBDE levels in people are generally 10–100 times higher than levels measured in people in Europe and Asia.

Production of PBDEs in the U.S. began in the 1970s and peaked in the late 1990s. Flame retardant manufacturers in the U.S. voluntarily stopped producing the PentaBDE (used in furniture foam) and OctaBDE (used in electronic products) varieties of PBDEs in 2004 and have begun producing alternative flame retardants; however, DecaBDE continues to be produced and used in the U.S., primarily in television casings. DecaBDE is classified as a possible human carcinogen by the U.S. Environmental Protection Agency.

A commercial ship is properly loaded when the ship’s waterline equals the ship’s Plimsoll line.

The Plimsoll line is a reference mark located on a ship’s hull that indicates the maximum depth to which the vessel may be safely immersed when loaded with cargo. This depth varies with a ship’s dimensions, type of cargo, time of year, and the water densities encountered in port and at sea. Once these factors have been accounted for, a ship’s captain can determine the appropriate Plimsoll line needed for the voyage.

Samuel Plimsoll (1824–1898) was a member of the British Parliament who was concerned with the loss of ships and crews due to vessel overloading. In 1876, he persuaded Parliament to pass the Unseaworthy Ships Bill, which mandated marking a ship’s sides with a line that would disappear below the waterline if the ship was overloaded. The line, also known as the Plimsoll mark, is found midship on both the port and starboard hulls of cargo vessels and is still used worldwide by the shipping industry.

LIDAR--Light Detection and Ranging--is a remote sensing method used to examine the surface of the Earth.

LIDAR, which stands for Light Detection and Ranging, is a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the Earth. These light pulses--combined with other data recorded by the airborne system--generate precise, three-dimensional information about the shape of the Earth and its surface characteristics.

A LIDAR instrument principally consists of a laser, a scanner, and a specialized GPS receiver. Airplanes and helicopters are the most commonly used platforms for acquiring LIDAR data over broad areas. Two types of LIDAR are topographic and bathymetric. Topographic LIDAR typically uses a near-infrared laser to map the land, while bathymetric lidar uses water-penetrating green light to also measure seafloor and riverbed elevations.

LIDAR systems allow scientists and mapping professionals to examine both natural and manmade environments with accuracy, precision, and flexibility. NOAA scientists are using LIDAR to produce more accurate shoreline maps, make digital elevation models for use in geographic information systems, to assist in emergency response operations, and in many other applications.

LIDAR data sets for many coastal areas can be downloaded from the NOAA Coastal Services Center’s Digital Coast web portal.

The Australian box jellyfish is considered the most venomous marine animal.

They may not look dangerous, but the sting from a box jellyfish could be enough to send you to Davy Jones's locker--a watery grave, that is.

Box jellyfish, named for their body shape, have tentacles covered in biological booby traps known as nematocysts--tiny darts loaded with poison. People and animals unfortunate enough to be injected with this poison may experience paralysis, cardiac arrest, and even death, all within a few minutes of being stung. But don’t choose the mountains over the ocean just yet. Of the 50 or so species of box jellyfish, also called sea wasps, only a few have venom that can be lethal to humans.

While box jellyfish are found in warm coastal waters around the world, the lethal varieties are found primarily in the Indo-Pacific region and northern Australia. This includes the Australian box jellyfish (Chironex fleckeri), considered the most venomous marine animal. Chironex fleckeri is the largest of the box jellyfish, with body sizes reaching up to one foot in diameter and thick, bootlace-like tentacles up to 10 feet long.

Box jellyfish have traits that set them apart from other jellyfish. Most notably, box jellyfish can swim--at maximum speeds approaching four knots--whereas most species of jellyfish float wherever the current takes them, with little control over their direction. Box jellyfish can also see. They have clusters of eyes on each side of the box. Some of these eyes are surprisingly sophisticated, with a lens and cornea, an iris that can contract in bright light, and a retina.

Their speed and vision leads some researchers to believe that box jellyfish actively hunt their prey, just shrimp and small fish … for now.

Oysters and Celery: Holiday Fare and Protective Lairs.

Roasted birds on the holiday table are often stuffed with a blend of breadcrumbs, herbs, and spices that includes chopped celery. Some stuffing recipes even call for chopped oysters, a briny bivalve that for centuries has been served raw on the half shell as a token of good luck in the coming year.

But did you know that oysters and celery also serve as important underwater habitats?

Oysters grow naturally on the bottoms of bays and rivers, and are also cultivated for food and pearls, in clusters called oyster beds. Over time, the mollusks’ rough, irregular shells form complex reefs where many aquatic species, such as fish and crabs, hunt for food and hide from predators.

Because they are filter feeders, oysters help keep the water clean, promoting the growth of underwater grasses such as wild celery (related in common name only to the crunchy stalks we stuff with cream cheese or peanut butter). Wild celery grows in the coarse, sandy soil of bays, rivers, and streams. Small fish and crustaceans are attracted to its long, ribbon-like stalks, which serve as nursery beds and provide abundant food for their young.

Wild celery is also a preferred food of many waterfowl, which voraciously consume its winter buds and roots. In fact, the scientific name of the canvasback duck, Aythya valisineria, derives from the scientific name of wild celery, Vallisneria americana.

As you celebrate the season, consider the diverse roles of oysters and celery. Far more than delectable treats on the holiday menu, they provide protective lairs and nutritious fare for our fragile and important aquatic communities.

A spring tide refers to the 'springing forth' of the tide during new and full moon.

During full or new moons--which occur when the Earth, sun, and moon are nearly in alignment--average tidal ranges are slightly larger. This occurs twice each month. The moon appears new (dark) when it is directly between the Earth and the sun. The moon appears full when the Earth is between the moon and the sun. In both cases, the gravitational pull of the sun is 'added' to the gravitational pull of the moon on Earth, causing the oceans to bulge a bit more than usual.

These are called 'spring tides,' a common historical term that has nothing to do with the season of spring. Rather, the term is derived from the concept of the tide "springing forth." Spring tides occur twice each lunar month all year long, without regard to the season.

Seven days after a spring tide, the sun and moon are at right angles to each other. When this happens, the bulge of the ocean caused by the sun partially cancels out the bulge of the ocean caused by the moon. This produces moderate tides known as 'neap tides,' which also occur twice a month.

Storm surge is the abnormal rise in seawater level during a storm, measured as the height of the water above the predicted astronomical tide. The surge is caused primarily by a storm’s winds pushing water onshore. The amplitude of the storm surge at any given location depends on the orientation of the coast line with the storm track; the intensity, size, and speed of the storm; and the local bathymetry.

Storm tide is the observed seawater level during a storm, resulting from the combination of storm surge and the astronomical tide. Astronomical tides are caused by the gravitational pull of the sun and the moon and have their greatest effects on seawater level during new and full moons—when the sun, the moon, and the Earth are in alignment. As a result, the highest storm tides are often observed during storms that coincide with a new or full moon.

For more information:
Storm Surge and Coastal Inundation
Storm Surge Risk Map for U.S. Coast
Center for Operational Oceanographic Products and Services

The Mariner's 1-2-3 Rule is the guideline mariners follow to keep out of a tropical storm or hurricane's path.

The Mariner's 1-2-3 rule, also referred to as the Danger Rule, is an important guideline mariners follow to keep out of a tropical storm or hurricane's path. It refers to the rounded long-term National Hurricane Center (NHC) forecast errors of 100-200-300 nautical miles at 24-48-72 hours, respectively.

The danger area to avoid is constructed by accounting for those errors and then broadened further to reflect the maximum tropical storm force (34 knot) wind radii forecast at each of those times by the NHC.

For more information:
Mariner's Guide For Hurricane Awareness
in the North Atlantic Basin National Hurricane Center Experimental Replacement Chart

A warning means that hurricane conditions are expected whereas a watch means that conditions are possible.

Hurricane warnings indicate that hurricane conditions (sustained winds of 74 mph or higher) are expected somewhere within the specified area. Because hurricane preparedness activities become difficult once winds reach tropical storm force (sustained winds of 39 to 73 mph), the hurricane warning is issued 36 hours in advance of the anticipated onset of tropical-storm-force winds to allow for important preparation.

During a hurricane warning, complete storm preparations and immediately leave the threatened area if directed by local officials.

A hurricane watch means that hurricane conditions (sustained winds of 74 mph or higher) are possible within the specified area. A hurricane watch is issued 48 hours in advance of the anticipated onset of tropical-storm-force winds in an area.

During a hurricane watch, prepare your home and review your plan for evacuation in case a hurricane or tropical storm warning is issued. Listen closely to instructions from local officials.

For more information:
National Hurricane Center

An AUV operates independently from the ship and has no connecting cables whereas ROVs are connected to an operator on the ship..

AUV stands for autonomous underwater vehicle and is commonly known as unmanned underwater vehicle. AUVs can be used for underwater survey missions such as detecting and mapping submerged wrecks, rocks, and obstructions that can be a hazard to navigation for commercial and recreational vessels.

An AUV conducts its survey mission without operator intervention. When a mission is complete, the AUV will return to a pre-programmed location where the data can be downloaded and processed.

A remotely operated vehicle (ROV) is an unoccupied underwater robot that is connected to a ship by a series of cables. These cables transmit command and control signals between the operator and the ROV, allowing remote navigation of the vehicle. An ROV may include a video camera, lights, sonar systems, and an articulating arm. The articulating arm is used for retrieving small objects, cutting lines, or attaching lifting hooks to larger objects.

While there are many uses for ROVs, some of the most common hydrographic applications include object identification (for submerged navigation hazards) and vessel hull inspections. An ROV is not intended to be a replacement for hydrographic diver investigations, but could serve as a substitute if divers are not available or diver safety is in question.

"Armoring" is the practice of using physical structures to protect shorelines from coastal erosion.

Coastal erosion--the loss of shoreline sediment--is a complex process that continuously reshapes the shoreline and can threaten coastal property. With approximately 350,000 structures located within 500 feet of the nation’s shoreline, erosion is a problem many U.S. coastal communities must address.

Coastal managers and property owners often attempt to stabilize coastal land and protect residential and commercial infrastructure along the coast by building shoreline armoring structures to hold back the sea and prevent the loss of sediment. Examples of such structures are seawalls, breakwaters, and riprap.

Shoreline armoring has both beneficial and detrimental effects. Armored shorelines can prevent sandy beaches, wetlands, and other intertidal areas from moving inland as the land erodes or sea levels rise, but they also have the potential to eliminate habitat for marine organisms and beach front for the public by restricting the natural movement of sediments. The key to shoreline stabilization, if it is required, is to use a site-specific stabilization method that balances the needs of the public and the needs of the natural system.

While coastal erosion is a natural process, the rate of erosion can be greatly influenced by human activities. Natural factors that contribute to erosion include sediment supply; geologic characteristics; changes in sea level; and the effects of waves, currents, tides, and wind--all of which vary by location. Human activities that can alter natural shoreline processes include beach nourishment (adding sand), dredging of ports and coastal approaches, construction of harbors and sediment-trapping dams, and the use of shoreline armor.

A nautical mile is based on the circumference of the Earth, and is equal to one minute of latitude. It is slightly more than a statute (land measured) mile (1 nautical mile = 1.1508 statute miles). Nautical miles are used for charting and navigating.

A knot is one nautical mile per hour (1 knot = 1.15 miles per hour). The term knot dates from the 17th Century, when sailors measured the speed of their ship by using a device called a "common log." This device was a coil of rope with uniformly spaced knots, attached to a piece of wood shaped like a slice of pie. The piece of wood was lowered from the back of the ship and allowed to float behind it. The line was allowed to pay out freely from the coil as the piece of wood fell behind the ship for a specific amount of time. When the specified time had passed, the line was pulled in and the number of knots on the rope between the ship and the wood were counted. The speed of the ship was said to be the number of knots counted (Bowditch, 1984).

NOAA's Office of Coast Survey has been the nation's nautical chartmaker for two centuries. Coast Survey provides nautical charts, hydrographic data, navigational assistance, and coastal observations to help position America for the future.

When the tide comes in from the Bay of Fundy, located off the Atlantic Coast between the State of Maine and the Province of New Brunswick, a tremendous amount of ocean water, called a current, flows swiftly into a confined area called the Western Passage before emptying upriver into Passamaquoddy Bay. After making a sharp right turn to the north and traversing a deep trench, flowing past an underwater mountain, and encountering several countercurrents, a portion of the current "pinches off" to form the huge circular current called Old Sow, and, often, several smaller ones, nicknamed "piglets." Circular currents of all sizes are commonly known as whirlpools, vortexes, eddies, and gyres.

Old Sow varies in size but has been measured at more than 250 feet in diameter, a little longer than two soccer fields laid end-to-end. While the turbulent water can be dangerous to small-craft mariners — some of whom have barely escaped a 12-foot drop into the Sow's gaping maw — its swirling motion has a positive environmental effect. It causes nutrients and tiny sea creatures normally found in the bay's colder, deeper waters to rise to the surface. This process, called upwelling, ensures good eating for the resident fish and seabirds.

So why is the whirlpool called "Old Sow?" According to folklore, the name refers to the "grunting" noise — which sounds like hungry pigs slurping up their slop — made by the giant churning gyre. "Sow" may also be a mispronunciation of the word "sough" (pronounced suff), which means "sucking noise" or "drain."

Mermaids -- those half-human, half-fish sirens of the sea -- are legendary sea creatures chronicled in maritime cultures since time immemorial. The ancient Greek epic poet Homer wrote of them in The Odyssey. In the ancient Far East, mermaids were the wives of powerful sea-dragons, and served as trusted messengers between their spouses and the emperors on land. The aboriginal people of Australia call mermaids yawkyawks -- a name that may refer to their mesmerizing songs.

The belief in mermaids may have arisen at the very dawn of our species. Magical female figures first appear in cave paintings in the late Paleolithic (Stone Age) period some 30,000 years ago, when modern humans gained dominion over the land and, presumably, began to sail the seas. Half-human creatures, called chimeras, also abound in mythology -- in addition to mermaids, there were wise centaurs, wild satyrs, and frightful minotaurs, to name but a few.

But are mermaids real? No evidence of aquatic humanoids has ever been found. Why, then, do they occupy the collective unconscious of nearly all seafaring peoples? That’s a question best left to historians, philosophers, and anthropologists.

Want to get away from it all?

You can't do better than a point in the Pacific Ocean popularly known as 'Point Nemo,' named after the famous submarine sailor from Jules Verne's Twenty Thousand Leagues Under the Sea.

This remote oceanic location is 2,688 kilometers from the nearest land--Ducie Island, part of the Pitcairn Islands, to the north; Motu Nui, one of the Easter Islands, to the northeast; and Maher Island, part of Antarctica, to the south.

For more information:
How much of the ocean have we explored? ]]> http://oceanservice.noaa.gov/facts/nemo.html Physical Properties Ocean Observations 4837ACB2-9322-4331-9048-FB0181EB29F5-45974-000E1B3BFC51ABD8-FFA Fri, 15 Jun 2012 08:11:35 -0400

Under the Endangered Species Act (ESA), a species may be listed as either threatened or endangered depending on their risk for extinction.

The ESA defines an endangered species as "any species which is in danger of extinction throughout all or a significant portion of its range." Endangered species are automatically protected by prohibitions of several types of "take," including harming, harassing, collecting, or killing, under Section 9 of the ESA. There are some limited exceptions to these rules listed in Section 10 of the ESA. The Kemp's ridley turtle, considered the smallest marine turtle in the world, is listed as an endangered species throughout its range of the Gulf of Mexico and entire U.S. Atlantic seaboard..

The ESA defines a threatened species as "any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range." Threatened species receive protections through separate regulations issued under Section 4(d) of the ESA. These regulations occur separately from the listing and detail what take prohibitions are in effect. Also called 4(d) rules, they can include the same prohibitions under Section 9. Elkhorn coral – a large, branching coral with thick and sturdy antler-like branches – is listed as a threatened species throughout its range.

NOAA scientists use the best scientific and commercial information available as the basis for their listing decisions. Scientists may not consider the economic impact of listing a particular species. A species must be listed if it is threatened or endangered due to any of the following five factors:

• present or threatened destruction, modification, or curtailment of its habitat or range;
• overutilization for commercial, recreational, scientific, or educational purposes;
• disease or predation;
• inadequacy of existing regulatory mechanisms; and
• other natural or human-made factors affecting its continued existence.

For more information:
Endangered Species Act Overview
Text of the Endangered Species Act
Elkhorn Coral
Kemp's Ridley Turtle
U.S. Fish and Wildlife Service Endangered Species Program

Research is underway to determine if invasive Asian tiger shrimp in U.S. Atlantic waters pose a threat to native species or the environment.

Asian tiger shrimp are native to Indo-Pacific, Asian, and Australian waters, but are now found along the southeast and Gulf coasts of the United States. While small numbers of this invasive species have been reported in U.S. waters for over a decade, sightings have notably increased over the past few years.

Researchers from the U.S. Geological Survey (USGS) and NOAA are now working with state agencies from North Carolina to Texas to look into whether these shrimp carry disease, compete for the same food source, or prey directly on native shrimp. An investigation is also underway to determine how this transplanted species reached U.S. waters, and what is behind a recent rise in sightings of the non-native shrimp.

Scientists have not yet officially deemed the Asian tiger shrimp “established” in U.S. waters, and no one is certain what triggered the recent round of increased sightings. The non-native shrimp species may have escaped from aquaculture facilities; however, there are no known Asian tiger shrimp farms presently in operation in the U.S. Ballast water from ships has been suggested as another pathway. Another possibility is that they are arriving on ocean currents from wild populations in the Caribbean or even as far away as Gambia, a west African nation where they are known to be established.

With so many alternative theories about where these shrimp are coming from and only a handful of juveniles reported, it is hard for scientists to conclude whether they are breeding or simply being carried in by currents.

To look for answers, NOAA and USGS scientists are examining shrimp collected from the Gulf and Atlantic coasts to look for subtle differences in their DNA, information which could offer valuable clues to their origins. This is the first look at the genetics of wild caught Asian tiger shrimp populations found in this part of the U.S., and may shed light on whether there are multiple sources.

NOAA scientists are also launching a research effort to understand more about the biology of these shrimp and how they may affect the ecology of native fisheries and coastal ecosystems. As with all non-native species, there are concerns over the potential for novel avenues of disease transmission and competition with native shrimp stocks, especially given the high growth rates and spawning rates compared with other species.

If you see one or more shrimp suspected to be an Asian tiger shrimp, you can help the research effort by noting the location and filing a report of the sighting with the USGS.

For more information:
Invasive Asian tiger shrimp (NOAA's National Centers for Coastal Ocean Science)
Asian tiger shrimp fact sheet (U.S. Geological Survey)
What are aquatic invasive species? (NOAA's Office of Oceanic and Atmospheric Research)
Aquatic Nuisance Species Task Force ]]> http://oceanservice.noaa.gov/facts/tigershrimp.html Animals Ocean Life BB08F50D-5695-4052-AE6D-CF56059563D0-15034-0002104739740476-FFA Fri, 27 Apr 2012 07:58:40 -0500 <img src="http://oceanservice.noaa.gov/facts/perigean-300.jpg" alt="graphic showing full moon and moon's perigee" title="What is a perigean spring tide?" width="300" border="0" /> <p>A perigean spring tide occurs when the moon is new or full and closest to Earth</p> <p>Around three or four times a year (in the spring and the fall), the new or full moon coincides closely in time with the perigee of the moon—the point when the moon is closest to the planet. These occurrences are often called 'perigean spring tides.' The difference between ‘perigean spring tide’ and normal tidal ranges for all areas of the coast is small. In most cases, the difference is only a couple of inches above normal spring tides.</p> http://oceanservice.noaa.gov/facts/perigean-spring-tide.html Currents Tides Ocean Observations BB08F50D-5695-4053-AE6D-CC56059563D0-15034-0012104739740476-FFA Tue, 03 Apr 2012 10:00:12 -0500

If you scoop up some water from the ocean in a clear glass and look at it closely, you'll see that it's chock full of tiny particles. Sea water contains dissolved salts, proteins, fats, dead algae, and a bunch of other bits and pieces of organic matter. If you shake this glass of ocean water vigorously, small bubbles will form on the surface of the liquid.

Sea foam forms in this way -- but on a much grander scale -- when the ocean is agitated by wind and waves. Each coastal region has differing conditions governing the formation of sea foams.

Algal blooms are one common source of thick sea foams. When large blooms of algae decay offshore, great amounts of decaying algal matter often wash ashore. Foam forms as this organic matter is churned up by the surf.

Most sea foam is not harmful to humans and are often an indication of a productive ocean ecosystem. But when large harmful algal blooms decay near shore, there are potential for impacts to human health and the environment. Along Gulf coast beaches during blooms of Karenia brevis, for example, popping sea foam bubbles send algal toxins airborne. The resulting aerosol can irritate the eyes of beach goers and poses a health risk for those with asthma or other respiratory conditions. Scientists studying the cause of a seabird die-offs off California in 2007 and in the Pacific Northwest in 2009 also found a soap-like foam from a decaying Akashiwo sanguinea algae bloom had removed the waterproofing on feathers, making it harder for birds to fly. This led to the onset of fatal hypothermia in many birds.

The Atlantic Ocean covers an area of approximately 41,105,000 square miles (106,460,000 square kilometers).

Covering approximately 20 percent of the Earth’s surface, the Atlantic Ocean is the second largest ocean basin in the world, following only the Pacific. However, it is only slightly larger than half the size of the Pacific Ocean.

The Atlantic Ocean lies between North and South America on the west and Europe and Asia on the east. Up north, the Atlantic connects to the Arctic Ocean and to the Southern Ocean to the south.

Scientists often divide the Atlantic into two basins: the North Atlantic and the South Atlantic. The North Atlantic, where waters sink after being chilled by arctic temperatures, is the start of the “global ocean conveyor,” a circulation pattern that helps regulate Earth’s climate.

The Atlantic Ocean derives its name from the Greek god, Atlas.

What is the largest ocean basin on Earth?

Ocean Conveyor Belt, NOAA Science on A Sphere

Datums are the basis for all geodetic survey work

A geodetic datum is an abstract coordinate system with a reference surface (such as sea level) that serves to provide known locations to begin surveys and create maps. In this way, datums act similar to starting points when you give someone directions. For instance, when you want to tell someone how to get to your house, you give them a starting point that they know, like a crossroads or a building address.

Geodesists and surveyors use datums to create starting or reference points for floodplain maps, property boundaries, construction surveys, levee design, or other work requiring accurate coordinates that are consistent with one another.

There are two main datums in the United States. Horizontal datums measure positions (latitude and longitude) on the surface of the Earth, while vertical datums are used to measure land elevations and water depths.

The horizontal datum can be accessed and used through a collection of specific points on the Earth whose latitude and longitude have been accurately determined by NOAA's National Geodetic Survey. One application of the horizontal datum is monitoring the movement of the Earth's crust. This type of monitoring is often used in places like the San Andreas Fault in California where many earthquakes occur.

The vertical datum is similarly "realized" through a collection of specific points on the Earth with known heights either above or below a nationally defined reference surface (e.g., mean sea level). Geodetic vertical datums are generally used to express land elevations. However, water level datums are a slightly different vertical datum, and are used as a reference level to which bathymetric soundings are referenced for nautical charts. Conversion between these two can be done through geodetic surveys at tide gauges.

Learn About Datums and Transformations

NOS Education: The Elements of Geodesy: Datums

National Geodetic Survey: Frequently Asked Questions

Introduction to Geodetic and Tidal Vertical Datums

The Sargasso Sea, located entirely within the Atlantic Ocean, is the only sea without a land boundary

The Sargasso Sea is a vast patch of ocean is named for a genus of free-floating seaweed called Sargassum. While there are many different
types of algae found floating in the ocean all around world, the Sargasso Sea is unique in that it harbors species of sargassum that are 'holopelagic' — this means that the algae not only freely floats
around the ocean, but it reproduces vegetatively on the high seas. Other seaweeds reproduce and begin life on the floor of the ocean.

Sargassum provides a home to an amazing variety of marine species. Turtles use sargassum mats as nurseries where hatchlings have food and shelter. Sargassum also provides essential habitat for marine species,such as shrimp, crab, and fish, that have adapted specifically to this floating algae. The Sargasso Sea is a spawning site for threatened and endangered eels, as well as white marlin, porbeagle shark, and dolphinfish. Humpback whales annually migrate through the Sargasso Sea. Commercial fish, such as tuna, and birds also migrate through the Sargasso Sea and depend on it for food.

While all other seas in the world are defined at least in part by land boundaries, the Sargasso Sea is defined only by ocean currents. It lies within the Northern Atlantic Subtropical Gyre. The Gulf Stream establishes the Sargasso Sea's western boundary, while the Sea is further defined to the north by the North Atlantic Current, to the east by the Canary Current, and to the south by the North Atlantic Equatorial Current. Since this area is defined by boundary currents, it's borders are dynamic, correlating roughly with the Azores High Pressure Center for any particular season.

What's the difference between an ocean and a sea? (Ocean Fact)

Sargassum: A Complex 'Island' Community at Sea (NOAA's Ocean Explorer)

Sampling the Sargassum Community: Dip Nets and Green-Light Lures (NOAA's Ocean Explorer)

NOAA's Harmful Algal Bloom Operational Forecast System in the Gulf of Mexico identifies whether or not a bloom of algae is likely to contain a toxic species, where it is, how big it is, where it's headed, and if it could become more severe in the near future. Like a weather forecast, this system provides officials advance warning to test and close beaches and shellfish beds more precisely and for a shorter period of time.

This system relies on satellite imagery, field observations, models, public health reports, and buoy data to provide information on bloom events. Forecasters create a public HAB conditions report using this data and information to provide the likelihood of respiratory irritation impacts to people in the area over the next three to four days.

In addition to the conditions report, NOAA issues a HAB Bulletin for federal, state, and local coastal resource managers. The bulletin includes a summary of present bloom conditions and boundaries based on water samples and satellite imagery. It forecasts whether or not conditions are favorable for bloom formation, where the bloom may go, and whether algae concentrations are likely to intensify in the near future.

Expert oceanographers at NOAA analyse available data and models in order to create accurate bulletins. To ensure the highest degree of accuracy, all operational HAB forecasts undergo secondary review prior to dissemination.

The Harmful Algal Bloom Operational Forecast System depends on the dedication, energy, and feedback from individuals at partner agencies and other organizations working on this issue. Blooms of harmful algae are not unique to the Gulf of Mexico, so NOAA continues to work with local agencies in Maine, Massachusetts, Ohio, Washington, Oregon, California and elsewhere in the U.S. to make new forecasts operational over the next five years.

NOAA Harmful Algal Bloom Operational Forecast System

Explore: Harmful Algal Blooms

Diving Deeper podcast (10.7.09) - Harmful Algal Blooms

Center for Operational Oceanographic Products and Services

National Centers for Coastal Ocean Science

You won't find Spirobranchus giganteus, also known as the Christmas tree worm, eating your fir tree this year. The common name for these worms is derived from their appearance, not their habitat or diet.

Each worm has two brightly colored crowns that protrude from its tube-like body. These Christmas tree-like crowns are composed of radioles, or hair-like appendages radiating from the worm's central spine. These appendages are used for respiration and to catch dinner, which typically consists of microscopic plants, or phytoplankton, floating in the water.

These worms are sedentary, meaning that once they find a place they like, they don’t move much. In fact, while the colorful crowns of these worms are visible, most of their bodies are anchored in burrows that they bore into live coral. When startled, Christmas tree worms rapidly retract into their burrows, hiding from would-be predators.

Christmas tree worms come in a variety of bright colors. They aren’t very big, averaging about 1.5 inches in length. However, because of their distinctive shape, beauty, and color, these worms are easily spotted. They are some of the most widely recognized polycheates, or marine burrowing, segmented worms out there.

Florida Keys National Marine Sanctuary: Christmas Tree Worms

Flower Garden Banks National Marine Sanctuary: Christmas Tree Worms

Encyclopedia of the Sanctuaries: Christmas Tree Worms

Corals have long been popular as souvenirs, for home decor, and in jewelry, but many consumers are unaware that these beautiful structures are made by living creatures. Fewer still realize that corals are dying off at alarming rates around the world.
Coral reefs are some of the most biologically rich and economically valuable ecosystems on Earth, but they are increasingly threatened by pollution, invasive species, fishing, disease, bleaching, and global climate change.

Strong consumer demand for coral, heightened over the holiday season, is another factor that is contributing to the decline of coral reefs.

Corals are popular as souvenirs, for home decor and in costume jewelry, yet corals are living animals that eat, grow and reproduce. It takes corals decades or longer to create reef structures, so leave corals and other marine life on the reef.

NOAA Coral Reef Watch

NOAA Coral Reef Conservation Program

NOAA Coral Reef Information System

10 Things You Need to Know About Marine Debris

Scientists are relying on computer models to predict the path of the debris, but models can only assume general direction and timing. Since winds and ocean currents constantly change, it is very difficult to predict an exact date and location for the arrival of any debris on U.S. coasts without more information.

Models run by NOAA researchers and other scientists show some debris could pass near, or wash ashore, in the Northwestern Hawaiian Islands as early as this winter, approach the West Coast of the United States and Canada in 2013, and then circle back to the main Hawaiian Islands in 2014.

NOAA is leading efforts within the federal government -- along with the U.S. Environmental Protection Agency (EPA) and other federal agencies, as well as non-governmental organizations and academia -- to understand the nature and amount of items that may wash ashore. NOAA is also working to understand the many possible impact scenarios and how to best protect our natural resources and coasts. It is considered highly unlikely that the tsunami-generated marine debris is contaminated with radioactive material because the debris washed out to sea before the release of radioactive water from the power plant. The EPA and the U.S. Food and Drug Administration are monitoring for radioactivity.

Frequently Asked Questions: Debris from Japan Tsunami

NOAA Marine Debris Program

Marine Debris (Diving Deeper podcast, 2.23.09)

10 Things You Need to Know About Marine Debris

The cryosphere is the frozen water part of the Earth system

There are places on Earth that are so cold that water is frozen solid. These areas of snow or ice, which are subject to temperatures below 0°C for at least part of the year, compose the cryosphere. The term “cryosphere” comes from the Greek word, “krios,” which means cold.

Ice and snow on land are one part of the cryosphere. This includes the largest parts of the cryosphere, the continental ice sheets found in Greenland and Antarctica, as well as ice caps, glaciers, and areas of snow and permafrost. When continental ice flows out from land and to the sea surface, we get shelf ice.

The other part of the cryosphere is ice that is found in water. This includes frozen parts of the ocean, such as waters surrounding Antarctica and the Arctic. It also includes frozen rivers and lakes, which mainly occur in polar areas.

The components of the cryosphere play an important role in the Earth’s climate. Snow and ice reflect heat from the sun, helping to regulate our planet’s temperature. Because polar regions are some of the most sensitive to climate shifts, the cryosphere may be one of the first places where scientists are able to identify global changes in climate.

For more information:
Why is the ocean salty?
U.S. National Ice Center
What is an iceberg?
NOAA's Arctic Theme Page

Tide and current data is available from NOAA's Center for Operational Products and Services website

Tides

Tide Predictions. Generate a graphical display or a tabular listing of daily high and low tide predictions for more than 3,000 locations around the nation. Predictions may be generated up to two years in advance.

Real-Time Tide Data. Access current water levels from over 3,000 tidal stations. For the Great Lakes region, see Great Lakes Real-Time Water Level Data.

Historic Tide Data. For a given NOAA tide station, retrieve historic tide data from the earliest to the most recent dates for which data is available. For the Great Lakes region, see Great Lakes Historic Water Level Data.

Sea Levels. View a global map depicting regional trends in sea level, with arrows representing the direction and magnitude of change.

Tides Online. Choose a tide station by state and location to view current tidal information, wind speeds, air pressure, and air temperature. For the Great Lakes region, visit Great Lakes Online.

Tsunami-Capable Tide Stations. Access high resolution, one-minute water level sample data used to support national tsunami warning and mitigation efforts.

Tide Station Index. Generate a per-state list of all NOAA tide stations, including station number, name, location, installation date, and more.

Tidal Datums. Access NOAA's tidal datums. Scientists use datums to define "normal" water levels as a starting point from which all measurements are made. The numbers that appear on a nautical chart represent water depths measured relative to such a datum.

Currents

Real-Time Current Data. View real-time current data collected by NOAA current meters around the nation.

Historic Current Data. View historic current data collected by active and retired NOAA current meters around the nation.

Tidal Current Predictions. Obtain tidal current predictions for more than 2700 tidal current stations nationwide.

Other CO-OPS Products and Services

PORTS®. NOAA's Physical Oceanographic Real-Time System (PORTS®) improves the safety and efficiency of maritime commerce and coastal resource management through the integration of real-time environmental observations, forecasts and other geospatial information. PORTS® measures and disseminates observations and predictions of water levels, currents, salinity, and meteorological parameters (e.g., winds, atmospheric pressure, air and water temperatures) that mariners need to navigate safely in and around key maritime ports around the nation.

NowCOAST. NowCOAST is a web mapping portal that provides spatially referenced links to thousands of real-time coastal observations and NOAA forecasts of interest to the marine community.

Storm QuickLook. Access near real-time oceanographic and meteorological observations at locations affected by a tropical cyclone.

Operational Forecast System. This service offers nowcasts and short-term forecasts for select regions (critical ports, harbors, estuaries, Great Lakes, and coastal waters). These real-time observations and forecasts deliver present and future states of water levels, along with currents and other relevant oceanographic variables, such as salinity and temperature.

'Turkeyfish' is another name for lionfish.

Viewed from the right angle, the ornate fins of the lionfish resemble turkey plumage. That's why 'turkeyfish' is one of the many imaginative names people use when referring to the lionfish.

Lionfish are native to the Indo-Pacific, but are now established along the southeast coast of the U.S., the Caribbean, and in parts of the Gulf of Mexico.

Since lionfish are not native to Atlantic waters, they have very few predators. They are carnivores that feed on small crustaceans and fish, including the young of important commercial fish species such as snapper and grouper.

How lionfish will affect native fish populations and commercial fishing industries has yet to be determined. What is known is that non-native species can dramatically affect native ecosystems and local fishing economies. Experts are carefully studying these invaders to better understand their role in, and threat to, Atlantic Ocean ecosystems.

For more information:
Learn more about invasive lionfish from NOAA's Center for Coastal Fisheries and Habitat Research

NOAA's Digital Coast provides the data, tools, and training that communities use to manage their coastal resources

Geospatial data alone is not enough. For data to be truly useful, additional training, tools, and information are often required. The Digital Coast provides this complete package in one place for coastal officials.

The Digital Coast is a cost-effective resource for coastal communities. Through the Digital Coast, users can find the information they need to explore the implications of sea level rise, conduct risk and vulnerability assessments, develop community green infrastructure plans, and much more. The site also provides valuable case studies to highlight how data and tools available from the Digital Coast have been used to address coastal management issues.

The Digital Coast's success is driven in large part by content contributions from many trusted sources, including federal, state, and local government agencies, non-profit organizations, and the private sector. A strong partnership group also helps to validate the information provided through the Digital Coast, ensuring that it is helpful and relevant to coastal managers. These partner organizations have found that the Digital Coast provides a way to work together on initiatives that not only benefit their organizations, but can also have a big impact on efforts to protect coastal resources and communities.

For more information:

Digital Coast

NOAA Coastal Services Center

Get the latest NOAA nautical charts and chart-related publications online at Nautical Charts & Publications.

Here’s a quick overview of the seven types of nautical charts that NOAA produces. Most electronic charts are updated weekly.

Traditional paper charts are what mariners have long used to navigate U.S. coastal waters, including the Great Lakes and U.S. territories. These full-color, large-format charts can be purchased through a nationwide network of private chart sellers.

Print-on-Demand (POD) nautical charts are timely versions of traditional paper charts. NOAA does not sell POD charts directly to the public. NOAA's commercial partner, OceanGrafix, lists authorized chart agents that sell POD charts.

Online Chart Viewer allows mariners to view the latest version of the full NOAA chart suite on their computer screens, pan and zoom around charts, and print chartlets at home.

NOAA Raster Navigational Charts® (NOAA RNC®) are full-color digital images of NOAA's entire suite of paper charts, updated continually with critical corrections. They can be used in many electronic charting systems and offer advanced functionalities such as real-time positioning. Available for free download in BSB format.

NOAA Electronic Navigational Charts® (NOAA ENCs) are NOAA's most powerful electronic charting product. These layered vector charts, available for free download, can be used in Electronic Chart and Display Information Systems (ECDIS).

PocketCharts™ are inexpensive, introductory charts to help novice boaters answer their two most common questions: "Where am I?" and "How do I get there?" PocketCharts cost about $6 at marine supply stores.

BookletCharts™ are free, print-at-home experimental products to help recreational boaters locate themselves on the water. Small-scale BookletCharts, in letter-sized format, contain all of the information on full-scale nautical charts. Note: During this experimental period, BookletCharts are not updated every week.

The law of the sea is a body of customs, treaties, and international agreements by which governments maintain order, productivity, and peaceful relations on the sea

Notable in the development of the law of the sea are two international conventions signed in the latter half of the 20th Century. One, the United Nations Convention on the Territorial Sea and the Contiguous Zone (1958), outlined the rights and responsibilities of States parties in their offshore waters. In 1982, the United Nations Convention on the Law of the Sea further outlined the role of States parties in their marine areas and beyond.

While the United States ratified the 1958 Convention, as of late 2011, it has not become a party to the 1982 Law of the Sea Convention. The United States recognizes that many of the principles in the 1982 Convention reflect customary international law; however, the U.S. is not bound by the agreement itself.

NOAA has a unique role in administering the law of the sea: Its nautical charts provide the scientifically derived baseline that marks the inner limit of the territorial sea and the outer limit of internal waters, such as bays and rivers. This determines where U.S. territorial waters begin for purposes of international law. The method of arriving at this baseline is described in the 1958 Convention and in the 1982 Convention.

The baselines, and thus the bounds, of offshore marine areas subject to jurisdiction are subject to ongoing revision due to shoreline changes such as accretion (addition of land) and erosion.

The location of maritime boundaries can have potentially far-reaching effects. As a result, NOAA works with other federal agencies, particularly the U.S. Department of State, to keep track of U.S. maritime boundaries and to represent such boundaries, where applicable, on U.S. navigational charts.

For more information:

Law of the Sea: History of the Maritime Zones under International Law

The name of the green sea turtle is derived from the reptile's greenish-colored fat

Adult green turtles are herbivores, which means they eat only plants such as seagrasses and algae. This diet is thought to give them their greenish-colored fat, hence the name, the green turtle.

Green turtles primarily use three types of habitat - beaches for nesting, open ocean convergence zones as juveniles, and coastal areas for benthic feeding as adults. In the U.S. Atlantic and Gulf of Mexico waters, green turtles are found in inshore and nearshore waters from Texas to Massachusetts, the U.S. Virgin Islands, and Puerto Rico. In the eastern North Pacific, green turtles have been sighted from Baja California to southern Alaska, but most commonly are seen south of San Diego. Also, in the central Pacific, green turtles are found around most tropical islands, including the Hawaiian Islands.

Green turtles face a host of threats in the marine environment. Incidental capture in fishing gear is an ongoing threat to green turtles, which also affects many other marine species. Green turtles also suffer from a disease known as fibropapillomatosis in some areas of the world. The main cause of the historical, worldwide decline of the green turtle was the long-term harvest of eggs, juveniles, and adults from their nesting beaches and feeding grounds. These harvests still continue in some areas of the world, compromising efforts to recover this species.

For more information:

NOAA Fisheries: Green Turtle Fact Sheet

NOAA considers a historical map or chart any map or chart that is not used today because it is out of date

The Office of Coast Survey maintains a historical map and chart collection of over 35,000 scanned, high-resolution images. The collection includes some of the nation’s earliest nautical charts, bathymetric maps, city plans, and Civil War battlefield maps.

Nautical charts are one of the most fundamental tools available to mariners, depicting the nature and form of the coast, the general configuration of the sea bottom, water depths, locations of dangers to navigation, locations and characteristics of human-made aids to navigation, and other features useful to the mariner.

Additionally, many of historical charts also depict events reflecting the geographic landscape at that time. For example, within the Office of Coast Survey's collection is a Chattanooga battlefield map from 1863 which is considered one of the best Civil War maps at that time.

While the historical map and chart collection dates back to the 1700s, the Office of Coast Survey, which formed in 1807 as the first federal scientific agency, produced its first charts in the early 1840s.

Electronic copies of images within the collection are available, by free download, to the public.

For more information:

Historical Map and Chart Collection, Office of Coast Survey

Charting a More Perfect Union: Special Collection of Civil War Charts

Diving Deeper: Episode 29 (December 16, 2010) - Historical Charts and Maps

New Online, a NOAA Civil War Collection

Ghostfishing is a term that describes what happens when derelict fishing gear 'continues to fish'.

Derelict fishing gear, sometimes referred to as "ghost gear," is any discarded, lost, or abandoned, fishing gear in the environment. This gear continues to fish and trap animals, entangle and potentially kill marine life, smother habitat, and act as a hazard to navigation. Derelict fishing gear, such as nets or traps and pots, is one of the main types of debris impacting the marine environment today.

The NOAA Marine Debris Program is working with fishermen to provide a place to dispose of fishing gear free of charge. Through the Fishing for Energy partnership, derelict gear is collected and recycled (e.g., metal) or used to create energy to power homes. In the first three years of this program, over one million pounds of derelict fishing gear was collected. The Fishing for Energy partnership includes NOAA, Covanta Energy Corporation, National Fish and Wildlife Foundation, and Schnitzer Steel.

For more information:

NOAA Marine Debris Program

10 Things You Need to Know About Marine Debris

Diving Deeper (audio podcast), Marine Debris (Feb. 23, 2009),

Sea cucumbers are animals, not vegetables.

Found only in salt water, more than a thousand species of sea cucumbers exist around the world. These squishy invertebrates are echinoderms, making them distant relatives to starfish and urchins. Unlike starfish or sea urchins, the bodies of sea cucumbers are covered with soft, leathery skin instead of hard spines.

If you ever encounter a sea cuke and he feels threatened, you could be in for a surprise. Some sea cucumbers shoot sticky threads at their enemies, entangling and confusing predators. Others can violently contract their muscles and shoot some of their internal organs out of their rear ends. The missing body parts are quickly regenerated.

Most sea cucumbers are scavengers, moving along the seafloor and feeding on tiny particles of algae or microscopic marine animals collected with tube feet that surround their mouths. The particles they grind down to smaller pieces are further broken down by bacteria and become part of the ocean’s nutrient cycle. This is a similar role to that which earthworms perform on land.

Sea cucumbers are enjoyed as meals for other critters such as fish and crabs. In some places, especially Asia, sea cucumbers are considered a delicacy and are enjoyed by humans.

Sea cukes are certainly a little odd, and definitely not something you’d ever find in your garden.

For more information:

Weird Fins: Sea cucumbers, NOAA’s National Marine Fisheries Service

Weird Animals: Sea Cucumbers, Ocean Today

NOAA's Storm QuickLook Provides Near Real-Time Ocean and Meteorological Conditions During a Tropical Storm.

When NOAA's National Weather Service issues a tropical storm warning for the U.S. or its territories, the Storm QuickLook is activated. This free online tool is a snapshot of near real-time coastal and weather observations for areas affected by a storm.

As the name suggests, the Storm QuickLook provides a ‘quick look’ at how a storm is affecting the coast. Here are some of the details provided by this report:

• Real-time water level and meteorological observations along the coast


• GIS map integrating storm track and intensity, satellite imagery, and NOS water level station locations


• Summary of present conditions across the affected region


• Predicted high tides at specific locations along the coast


• Latest NOAA Weather Service Public Advisory Text

QuickLook is served up by the Center for Operational Oceanographic Products and Services, NOAA’s tides and currents experts. While updates are generally published online four times a day, QuickLook data is updated once every six minutes during storm events. The online product may be released more frequently as circumstances (such as storm landfall) dictate.

For more information:
In-Depth Description of NOAA's Storm QuickLook
Center for Operational Oceanographic Products and Services
QuickLook Archive

Weather reflects short-term conditions of the atmosphere while climate is the average daily weather for an extended period of time at a certain location.

We hear about weather and climate all of the time. Most of us check the local weather forecast to plan our days. And climate change is certainly a "hot" topic in the news. There is, however, still a lot of confusion over the difference between the two.

Think about it this way: Climate is what you expect, weather is what you get.

Weather is what you see outside on any particular day. So, for example, it may be 75 degrees and sunny or it could be 20 degrees with heavy snow. That's the weather.

Climate is the average of that weather. For example, you can expect snow in the Northeast in January or for it to be hot and humid in the Southeast in July. This is climate. The climate record also includes extreme values such as record high temperatures or record amounts of rainfall. If you've ever heard your local weather person say "today we hit a record high for this day," she is talking about climate records.

So when we are talking about climate change, we are talking about changes in long-term averages of daily weather. In most places, weather can change from minute-to-minute, hour-to-hour, day-to-day, and season-to-season. Climate, however, is the average of weather over time and space.

For more information:

National Weather Service

NOAA Climate Services Portal

Coastal Climate Adaptation Resources

Diving Deeper: Preparing for Climate-Related Impacts

Although surface oil would rapidly dissipate by a passing hurricane, trace oil or residue in the deep ocean would not be disturbed; however, wave energy could uncover or move nearshore submerged mats or oil buried along shorelines as a result of older spills or natural seeps.

Following oil spills, such as the BP Deepwater Horizon incident in 2010, concerns may exist about how oil residue in deeper water could be impacted if a hurricane passes over the affected area. Oil residues in deep-ocean sediments will not be disturbed by passing hurricanes and trace amounts of oil dissolved in the water column will become even more dispersed.

Wave energy from passing hurricanes may erode shorelines and uncover and move buried oil leftover by a large spill or by natural seeps in the seafloor. Oil stranded in nearshore submerged oil mats could also be remobilized.

Specifically in regards to the Deepwater Horizon spill, any remaining oil that could re-mobilize would be heavily weathered and would continue to degrade and would not travel long distances along the Gulf Coast. Oil not detected or removed might be transported locally along a shoreline or carried inland to the extent of storm surge, but would not move long distances along or across the Gulf Coast.

In addition to oil, hurricanes can generate huge amounts of debris along shorelines and inland to include damage from boats, cars, households, and facilities. Any fresh oil along the Gulf Coast that is observed during hurricane or non-hurricane events should be reported to the U.S. Coast Guard by calling the National Response Center at 1-800-424-8802.

For more information:

Office of Response and Restoration

NOAA Deepwater Horizon Archive

NOAA Gulf Spill Restoration

Explore: Oil and Chemical Spills

National Hurricane Center

NOAAWatch

Ferdinand Magellan named the Pacific Ocean.

In 1519, Portuguese explorer Ferdinand Magellan, in the employ of Spain, began a journey across the Atlantic Ocean to seek a western route to the Spice Islands via South America.

After braving perilous seas and navigating through what are now known as the Straits of Magellan, his small fleet entered an unfamiliar ocean in Nov. 1520.

When Magellan and his crew entered the Pacific Ocean after their long journey, they thought that the Spice Islands were close at hand. Little did they know that their destination remained thousands of miles away. The explorers had ventured into the largest ocean on Earth.

Covering approximately 155 million square kilometers (59 million square miles) and containing more than half of the free water on Earth, the Pacific is by far the largest of the world's ocean basins. All of the world's continents could fit into the Pacific basin!

For more information:

Yes, there is gold in the ocean.

Ocean waters do hold gold – nearly 20 million tons of it. However, if you were hoping make your fortune mining the sea, consider this: Gold in the ocean is so dilute that its concentration is on the order of parts per trillion. Each liter of seawater contains, on average, about 13 billionths of a gram of gold.

There is also (undissolved) gold in/on the seafloor. The ocean, however, is deep, meaning that gold deposits are a mile or two under water. And once you reach the ocean floor, you’ll find that gold deposits are also encased in rock that must be mined through. Not easy.

Currently, there really isn’t a cost-effective way to mine or extract gold from the ocean to make a profit. But, if we could extract all of that gold, there’s enough of it that each person on Earth could have nine pounds of the precious metal. Eureka!

For more information:
Why is the ocean salty? – U.S. Geological Survey
“Ocean Planet” Oceanographic Facts – NASA SeaWIFS

Sea stars, commonly called, "starfish," are not fish

Sea stars live underwater, but that is where their resemblance to fish ends. They do not have gills, scales, or fins. Sea stars live only in saltwater. Sea water, instead of blood, is actually used to pump nutrients through their bodies via a 'water vascular system.'

Also, sea stars move by using tiny tube feet located on the underside of their bodies. Adult sunflower sea stars can move at the astonishing speed of one meter per minute using 15,000 tube feet. Tube feet also help sea stars hold their prey.

Sea stars are related to sand dollars, sea urchins, and sea cucumbers, all of which are echnioderms, meaning that they have five-point radial symmetry. However, this does not mean that all sea stars have five arms and species with 10, 20, or even 40 arms exist! If one of these arms is lost, a sea star has the amazingly ability to regenerate it.

For more information:
Sunflower sea star, National Marine Fisheries Service
Six-rayed sea star, National Marine Fisheries Service

Only about five percent of the body of a jellyfish is solid matter; the rest is water

Fascinating, elegant, and mysterious to watch in the water, take a jellyfish out of the water, and it becomes a much less fascinating blob. This is because jellyfish are about 95 percent water.

Lacking brains, blood, or even hearts, jellyfish are pretty simple critters. They are composed of three layers: an outer layer, called the epidermis; a middle layer made of a thick, elastic, jelly-like substance called mesoglea; and an inner layer, called the gastrodermis. An elementary nervous system, or nerve net, allows jellyfish to smell, detect light, and respond to other stimuli. The simple digestive cavity of a jellyfish acts as both its stomach and intestine, with one opening for both the mouth and the anus.

These simple invertebrates are members of the phylum Cnidaria, which includes creatures such as sea anemones, sea whips, and corals. Like all members of the phylum, the body parts of a jellyfish radiate from a central axis. This “radial symmetry” allows jellyfish to detect and respond to food or danger from any direction.

Jellyfish have the ability to sting with their tentacles. While the severity of stings varies, in humans, most jellyfish stings result only in minor discomfort.

For more information:
Jellyfish Gone Wild, National Science Foundation
Mapping Sea Nettles in the Chesapeake Bay

The health of submerged aquatic vegetation is an important environmental indicator of overall ocean and estuary health.

Seagrasses in bays and lagoons, for instance, are vital to the success of small invertebrates and fish. These small creatures are a food source for commercial and recreational fish.

Seagrasses also stabilize sediments, generate organic material needed by small invertebrates, and add oxygen to the surrounding water.

Underwater vegetation in shallow coastal waters also supports a wide diversity of marine creatures by providing spawning, nursery, refuge, and foraging grounds for many species.

For more information:
Benthic Habitat Mapping, NOAA Coastal Services Center (CSC)
Benthic Habitat Data, CSC

Some seaweeds are microscopic, such as the phytoplankton that live suspended in the water column and provide the base for most marine food chains. Some are enormous, like the giant kelp that grow in abundant “forests” and tower like underwater redwoods from their roots at the bottom of the sea. Most are medium-sized, come in colors of red, green, brown, and black, and randomly wash up on beaches and shorelines just about everywhere.

The vernacular “seaweed” is a bona-fide misnomer, because a weed is a plant that spreads so profusely it can harm the habitat where it takes hold. (Consider kudzu, the infamous “mile-a-minute vine” that chokes waterways throughout the U.S. Southeast). Not only are the fixed and free-floating “weeds” of the sea utterly essential to innumerable marine creatures, both as food and as habitat, they also provide many benefits to land-dwellers, notably those of the human variety.

• Seaweed is chock-full of vitamins, minerals, and fiber, and can be tasty. For at least 1,500 years, the Japanese have enrobed a mixture of raw fish, sticky rice, and other ingredients in a seaweed called nori. The delectable result is a sushi roll.
• Many seaweeds contain anti-inflammatory and anti-microbial agents. Their known medicinal effects have been legion for thousands of years; the ancient Romans used them to treat wounds, burns, and rashes. Anecdotal evidence also suggests that the ancient Egyptians may have used them as a treatment for breast cancer.
• Certain seaweeds do, in fact, possess powerful cancer-fighting agents that researchers hope will eventually prove effective in the treatment of malignant tumors and leukemia in people. While dietary soy was long credited for the low rate of cancer in Japan, this indicator of robust health is now attributed to dietary seaweed.
• These versatile marine plants and algae have also contributed to economic growth. Among their many uses in manufacturing, they are effective binding agents (emulsifiers) in such commercial goods as toothpaste and fruit jelly, and popular softeners (emollients) in organic cosmetics and skin-care products.

All across our ocean wafts a wonderful “weed,” indeed.

For more information:
Seaweeds, Olympic Coast National Marine Sanctuary |Kelp Forests, Office of National Marine Sanctuaries

While it's relatively common to spot unidentified dark or reddish patches on the surface of the ocean in coastal areas around the U.S., it's not always easy to discern by sight what the substance is that's creating the disturbance. Often, offshore patches of discolored water are the result of algal blooms or oil slicks.

Algal blooms occur when colonies of algae—simple ocean plants that live in the sea—grow out of control. While algal blooms come in many colors (and some have no color at all), they are popularly known as 'red tides' because some are deep red in color.

Oil slicks, on the other hand, are simply films of oil floating on top of the water. While some slicks may be a few inches thick, most are thinner than a human hair. They may form naturally, but they are often introduced by man in incidents ranging from refined fuels or crude oil spilled from a ship to larger events such as last year's Deepwater Horizon oil spill. Oil sometimes emulsifies under certain conditions. Emulsified oil is a mixture of oil and water that often resembles chocolate mousse or pudding.

How do you tell the difference? It can be difficult. Even the experts can be fooled, especially when looking at the ocean from an aircraft.

Color. Oil can vary greatly in color, from the commonly expected black or dark brown, to red, orange, yellow, and even some more exotic colors. When oil becomes emulsified, its color becomes much lighter. For example, South Louisiana crude oil is generally a dark red, but appears bright red to orange when emulsified—as it did during the Deepwater Horizon spill. If the oil has a reddish hue, it may be mistaken for so-called "red tide." Once the emulsion breaks, the color reverts back to its normal dark color. Once an oil slick spreads out and becomes very thin, the color varies from grey to silver. It's easier to observe from a boat or a plane than it is from on the beach, but if you see a thin film that is rainbow-colored, you're looking at oil. However, other than rainbow sheen, both oil and algal blooms can have a large range in colors that are similar, and algal blooms often create sheens.

Odor. The most reliable difference is odor. Oil slicks nearly always have a characteristic petroleum smell. Algal blooms may have a strong smell as well, but the smell is distinctly different from that of the more-familiar smell of petroleum.

In the water or just on top? Algal blooms are mostly in the water column although often in the upper layers, but they may have a floating layer. Oil slicks are generally only floating on the surface. But certain oils may be naturally or chemically dispersed into the water column.

Nighttime Bioluminescence.: Oil isn't bioluminescent—it doesn't produce light—but some of the algae that form surface blooms do. The light comes from chemical reactions in the algal cells. So when it's dark out, the water may glow—especially when waves break. During the day, you can take some water into a very dark room, let your eyes adapt to the darkness for several minutes, and then swirl the container. A blue glow or individual flashes of light indicate bioluminescent algae. Keep in mind, though, that some red tide algae do not produce light.

Unsure? Sometimes it's best to leave it to the experts. If you think you see oil on the water, report it to the National Response Center at 1-800-424-8802.

For more information
What is a 'red tide?' (Ocean Fact)
Why do harmful algal blooms occur? (Ocean Fact)
What is Natural Resource Damage Assessment? (Ocean Fact)
How does oil impact marine life? (Ocean Fact)
Oil and Chemical Spill Incident News, NOAA's Office of Response & Restoration
Oil & Chemical Spills
Harmful Algal Blooms
Responding to Oil Spills (podcast)
Harmful Algal Blooms (podcast)
Oil in the Ocean (video)
Predicting Harmful Algal Blooms (video)

The Earth’s outer crust is made up of a series of tectonic plates that move over the surface of the planet. In areas where the plates come together, sometimes volcanoes will form. Volcanoes can also form in the middle of a plate, where magma rises upward until it erupts on the sea floor, at what is called a “hot spot.”

The Hawaiian Islands where formed by such a hot spot occurring in the middle of the Pacific Plate. While the hot spot itself is fixed, the plate is moving. So, as the plate moved over the hot spot, the string of islands that make up the Hawaiian Island chain were formed.

The Hawaiian Islands form an archipelago that extends over a vast area of the North Pacific Ocean. The archipelago is made up of 132 islands, atolls, reefs, shallow banks, shoals, and seamounts stretching over 2,400 kilometers (1,500 miles) from the island of Hawaii in the southeast to Kure Atoll in the northwest.

For more information:
Hawaiian Archipelago, Coral Reef Information System
Seamounts and Hot Spots, New Millennium Observatory

Water levels in the Great Lakes have long-term, annual, and short-term variations. Long-term variations depend on precipitation and water storage over many years. Annual variations occur with the changing seasons. There is an annual high in the late spring and low in the winter. These changes occur at a rate that can be measured in feet per month.

True tides, changes in water level caused by the gravitational forces of the sun and moon, do occur in a semi-diurnal (twice daily) pattern on the Great Lakes. Studies indicate that the Great Lakes spring tide, the largest tides caused by the combined forces of the sun and moon, is less than five centimeters (two inches) in height. These minor variations are masked by the greater fluctuations in lake levels produced by wind and barometric pressure changes.

Consequently, the Great Lakes are considered to be essentially non-tidal.

For more information:
Center for Operational Oceanographic Products and Services
Great Lakes Water Level Data
Great Lakes Online
Tide Predictions and Data Frequently Asked Questions
Tides Tutorial, NOS Education
What are Tides? - Diving Deeper audio podcast

The ocean is the lifeblood of Earth, covering more than 70 percent of the planet's surface, driving weather, regulating temperature, and ultimately supporting all living organisms. Throughout history, the ocean has been a vital source of sustenance, transport, commerce, growth, and inspiration.

Yet for all of our reliance on the ocean, 95 percent of this realm remains unexplored, unseen by human eyes.

NOAA’s Office of Ocean Exploration and Research is leading efforts to explore the ocean by supporting expeditions to investigate and document unknown and poorly known areas of the ocean. These expeditions represent a bold and innovative approach by infusing teams of scientist-explorers with a "Lewis and Clark" spirit of discovery and equipping them with the latest exploration tools.

From mapping and describing the physical, biological, geological, chemical, and archaeological aspects of the ocean to understanding ocean dynamics, developing new technologies, and helping us all unlock the secrets of the ocean, NOAA is working to increase our understanding of the ocean realm.

For more information:
NOAA Ocean Explorer

Lightering is the process of removing oil or other hazardous chemicals from a compromised vessel to another vessel to prevent oil from spilling into the surrounding waters.

Lightering is not possible in all oil spill scenarios. It depends on many factors including the type of oil that is spilled. As time passes, the oil can become more viscous, or thicker, and therefore more difficult to pump. This can, in turn, make lightering difficult, if not impossible. While there are benefits to removing oil in this way, there can also be accidents and spills that result from lightering.

Lightering is also used to transfer cargo between vessels of different sizes like a barge and a bulker or oil tanker to reduce the vessel's draft in order to enter port facilities.

For more information:

Office of Response and Restoration

Office of Coast Survey

The NOAA Air Gap system is a tool that measures the clearance between the water surface and the bridge.

Air gap measurements are updated every six minutes to account for changes in water level and bridge height, due to bridge traffic, air temperature, and other factors. Data on air gap along with real-time data on water conditions like tides, currents, and winds, help ship captains safely enter and leave U.S. ports. This information is critical for a ship captain to safely navigate a ship under a bridge.

For more information:

Center for Operational Oceanographic Products and Services

Physical Oceanographic Real Time System

Ship Under a Bridge

NOAA's Air Gap Technology Sends USS New York Down the Mississippi River for Sea Trials

Papahānaumokuākea Marine National Monument preserves one of the most untouched areas of coral reef in the world.

The main difference between national marine sanctuaries and marine national monuments is the designation process and the laws under which they are established. Sanctuaries are designated by the Secretary of Commerce, through NOAA, under the National Marine Sanctuaries Act (NMSA). The NMSA requires extensive public process, local community engagement, stakeholder involvement, and citizen participation, both prior to and following designation.

Monuments are designated by Presidential Proclamation, via the Antiquities Act of 1906. The Act is very simple, has changed little in more than a century, provides broad power to set aside public areas for protection, and requires no public process.

The NOS Office of National Marine Sanctuaries manages 13 national marine sanctuaries and one national marine monument.  At more than 140,000 square miles (362,598 square kilometers), Papahānaumokuākea Marine National Monument is the largest protected area in the United States, stretching the length of the Northwestern Hawaiian Islands. The Monument, co-managed with the State of Hawai’i and the Department of the Interior, was designated on June 15, 2006 by President George W. Bush under Presidential Proclamation 8031.

For more information:
Papahānaumokuākea Marine National Monument
Office of National Marine Sanctuaries
NOAA Fisheries Marine National Monument Program

VDatum stands for Vertical Datum Transformation, an innovative and evolving software tool under development by NOAA's National Ocean Service. Free to the public, VDatum's primary purpose is to convert elevation data from various sources into a common reference system.

A common reference system is important because irregularities can occur when maps and charts are created from different data sources. In a coastal area, for example, a shift in elevation on a gently sloping beach may change the overall depiction of the shoreline.

VDatum's capabilities to transform and fuse diverse elevation data benefits coastal applications including inundation modeling (e.g., storm surge, tsunami, sea-level rise impacts), ecosystem management and coastal planning, hydrographic surveying using Kinematic GPS for vertical referencing, and shoreline delineation from LiDAR data.

VDatum coverage will be complete in all coastal regions of the U.S. by 2011, and in Puerto Rico, the U.S. Virgin Islands, Hawaii, Alaska, and the Pacific territories thereafter. The goal is to develop a VDatum utility throughout the country that will foster more effective sharing of elevation data and, eventually, to link such data through national databases.

VDatum is written for use solely within the United States and its territories. NOAA's National Geodetic Survey, Office of Coast Survey, and Center for Operational Oceanographic Products and Services are the joint developers of VDatum software.

For more information
Welcome to VDatum!
What is the National Spatial Reference System
NOAA's National Geodetic Survey

Salt marshes are coastal wetlands that are flooded and drained by salt water brought in by the tides. They are marshy because the soil may be composed of deep mud and peat. Peat is made of decomposing plant matter that is often several feet thick. Peat is waterlogged, root-filled, and very spongy. Because salt marshes are frequently submerged by the tides and contain a lot of decomposing plant material, oxygen levels in the peat can be extremely low—a condition called hypoxia. Hypoxia is caused by the growth of bacteria which produce the sulfurous rotten-egg smell that is often associated with marshes and mud flats.

Salt marshes occur worldwide, particularly in middle to high latitudes. Thriving along protected shorelines, they are a common habitat in estuaries. In the U.S., salt marshes can be found on every coast. Approximately half of the nation's salt marshes are located along the Gulf Coast.

These intertidal habitats are essential for healthy fisheries, coastlines, and communities—and they are an integral part of our economy and culture. They also provide essential food, refuge or nursery habitat for more than 75 percent of fisheries species, including shrimp, blue crab, and many finfish.

Salt marshes also protect shorelines from erosion by buffering wave action and trapping sediments. They reduce flooding by slowing and absorbing rainwater and protect water quality by filtering runoff, and by metabolizing excess nutrients.

For more information

Natural Resource Damage Assessment (NRDA) is the process that federal agencies like NOAA, together with the states and Indian tribes, use to evaluate the impacts of oil spills, HAZMAT incidents and hazardous waste sites, and ship groundings on natural resources both along the nation's coast and throughout its interior.

NOAA and these other entities, referred to collectively as natural resource trustees, work together to identify the extent of resource injuries, the best methods for restoring them, and the type and amount of restoration required.

NOAA's responsibilities in a NRDA include:

• A preliminary assessment to determine whether any impacts have occurred. Scientists may collect data, review scientific literature, and use mathematical models to help predict the effects of the incident on trust resources.
• Injury assessment and restoration planning, during which NOAA quantifies the injuries through scientific and economic studies and then identifies potential restoration projects (e.g., beach and shoreline enhancements, creation of oyster reefs or other shellfish habitats, and programs to monitor the recovery of species and habitats).
• Restoration, which aims either to return the injured resources to their original condition, or, if that is not possible, to compensate the public for its losses. During this phase, the co-trustees work with the Responsible Party (the entity whose property or actions caused the injury), who pays for the assessment and restoration and often participates in restoration activities.

In the event that the Responsible Party refuses to pay damages, NOAA and its co-trustees may file a lawsuit or submit a claim to the Oil Spill Liability Trust Fund.

For more information
NOAA's Damage Assessment, Remediation, and Restoration Program (DARRP)
Gulf Spill Restoration
NOAA Office of Response and Restoration
Oil Spill Liability Trust Fund
Natural Resource Restoration

In California, for example, nesting and migrant seabird populations are significant resources with colonies throughout the state. Over time, these populations have been impacted by a variety of man-made sources, including oil spills, gill-net and other fisheries, various contaminants, habitat destruction, introduced predators, and human disturbance.

These disturbances can cause nesting seabirds to flee from and abandon their nests, leaving eggs or chicks exposed to predators, or causing eggs to fall from the nest. In some cases, disturbances can cause complete breeding failure of a seabird colony, and ultimately may cause colony abandonment. These disturbance events can result in a reduction of the long-term health and survival of affected marine species, and when coupled with changing oceanic conditions and other human-induced stressors, cumulative small impacts can impart large-scale harm.

For more information:
Seabird Protection Network
Gulf of the Farallones National Marine Sanctuary
Office of National Marine Sanctuaries

Have you ever wondered about the main differences between seals and their "second cousins," the sea lions?

Both seals and sea lions, together with the walrus, are pinnipeds, which means "fin footed" in Latin.

But seals' furry, generally stubby front feet — thinly webbed flippers, actually, with a claw on each small toe — seem petite in comparison to the mostly skin-covered, elongated fore flippers that sea lions possess.

Secondly, sea lions have small flaps for outer ears. The "earless" or "true" seals lack external ears altogether. You have to get very close to see the tiny holes on the sides of a seal’s sleek head.

Third, sea lions are noisy. Seals are quieter, vocalizing via soft grunts.

Fourth, while both species spend time both in and out of the water, seals are better adapted to live in the water than on land. Though their bodies can appear chubby, seals are generally smaller and more aquadynamic than sea lions. At the same time, their hind flippers angle backward and don't rotate. This makes them fast in the water but basic belly crawlers on terra firma.

Sea lions, on the other hand, are able to "walk" on land by rotating their hind flippers forward and underneath their big bodies. This is why they are more likely to be employed in aquaria and marine shows.

Finally, seals are less social than their sea-lion cousins. They spend more time in the water than sea lions do and often lead solitary lives in the wild, coming ashore together only once a year to meet and mate.

Sea lions congregate in gregarious groups called herds or rafts that can reach upwards of 1,500 individuals. It's common for scores of them to haul out together and loll about in the sand, comprising an amorphous pile in the noonday sun.

For more information
Pinnipeds: Seals, Sea Lions, and Walruses, NOAA Fisheries Office of Protected Resources
Marine Mammals, NOAA Fisheries Office of Protected Resources
NOAA's National Marine Sanctuaries

At sea level, the air that surrounds us presses down on our bodies at 14.7 pounds per square inch (1 bar). You don't feel it because the fluids in your body are pushing outward with the same force.

Dive down into the ocean even a few feet, though, and a noticeable change occurs. You can feel an increase of pressure on your eardrums. This is due to an increase in hydrostatic pressure, the force per unit area exerted by a liquid on an object.

The deeper you go under the sea, the greater the pressure of the water pushing down on you. For every 33 feet (10 meters) you go down, the pressure increases by 14.7 psi (1 bar). In the deepest ocean, the pressure is equivalent to the weight of an elephant balanced on a postage stamp, or the equivalent of one person trying to support 50 jumbo jets!

Many animals that live in the sea have no trouble at all with high pressure. Whales, for instance, can withstand dramatic pressure changes because their bodies are more flexible. Their ribs are bound by loose, bendable cartilage, which allows the rib cage to collapse at pressures that would easily snap our bones.

A whale's lungs can also collapse safely under pressure, which keeps them from rupturing. This allows sperm whales to hunt for giant squid at depths of 7,000 feet (2,100 meters) or more.

For more information:
NOAA's Ocean Explorer

The National Estuarine Research Reserve System is a network of 28 areas representing different biogeographic regions of the United States. The reserves are protected for long-term research, water quality monitoring, education, and coastal stewardship. Each reserve is managed on a daily basis by a lead state agency or university, with input from local partners. NOAA provides funding, national guidance, and technical assistance.

Reserve staff work with local communities and regional groups to address natural resource management issues, such as non-point source pollution, habitat restoration, and invasive species. Through integrated research and education, the reserves help communities develop strategies to deal successfully with their coastal resource issues.

Reserves provide adult audiences with training on estuarine issues of concern in their local communities. They also offer field classes for K-12 students and support teachers through professional development programs in marine education.

For more information:
NOAA's National Estuarine Research Reserve System
NOS Topic Page: National Estuarine Research Reserves
Estuaries.gov
Estuaries (Diving Deeper podcast, 4.20.09)
Office of Ocean and Coastal Resource Management

Corals are sessile, which means that they permanently attach themselves to the ocean floor, essentially "taking root" like most plants do. We certainly cannot recognize them by their faces or other distinct body parts, as we can most other animals.

So what are corals, anyway?

Corals actually comprise an ancient and unique partnership, called a symbiosis, that benefits both animal and plant life in the ocean. Corals are animals, though, because they do not make their own food, as plants do. Corals have tiny, tentacle-like arms that they use to capture their food from the water and sweep into their inscrutable mouths.

Any structure that we call "a coral" is, in fact, made up of hundreds to thousands of tiny coral creatures called polyps. Each soft-bodied polyp—most no thicker than a nickel—secretes a hard outer skeleton of limestone (calcium carbonate) that attaches either to rock or the dead skeletons of other polyps.

In the case of stony or hard corals, these polyp conglomerates grow, die, and endlessly repeat the cycle over time, slowly laying the limestone foundation for coral reefs and giving shape to the familiar corals that reside there. (The soft corals, which include sea fans, sea pansies, and anemones, are the hard corals' cousins and also play important roles in the reef ecosystem.)

Most corals contain algae called zooxanthellae (pronounced zo-UH-zan-thuh-lay), which are plantlike organisms. Residing within the coral's tissues, the microscopic algae are well protected and make use of the coral's metabolic waste products for photosynthesis, the process by which plants make their own food.

The corals benefit, in turn, as the algae produce oxygen, remove wastes, and supply the organic products of photosynthesis that corals need to grow, thrive, and build up the reef.

More than merely a clever collaboration that has endured between some of the tiniest ocean animals and plants for some 25 million years, this mutual exchange is the reason why coral reefs are the largest structures of biological origin on Earth, and rival old-growth forests in the longevity of their ecological communities.

For more information:
What are Corals and Coral Reefs? – NOAA's Coral Reef Information System
Corals – NOS Education
Coral Reef Conservation
NOAA's Coral Reef Conservation Program

Reef-building corals are restricted in their geographic distribution by factors such as the temperature and the salinity (salt content) of the water. The water must also be clear to permit high light penetration.

Because of these environmental restrictions, reefs generally are confined to tropical and semitropical waters. The diversity of reef corals (the number of species), decreases in higher latitudes up to about 30° north and south, beyond which reef corals are usually not found.

Generally, there are about twice as many coral species in Pacific Ocean reefs as in Atlantic Ocean reefs.

For more information:
What are Coral Reefs?  NOAA’s Coral Reef Information System
Coral Reef Biology, NOAA's Coral Reef Information System
Corals Tutorial, NOS Education

More specifically, the EEZ includes waters three to 200 miles (five to 322 kilometers) offshore (or nine to 200 miles – 14.5 to 322 kilometers – offshore in western Florida and Texas). Coastal states are responsible for inshore waters out to three miles (five kilometers) of the coast (or nine miles, 14.5 kilometers, off the west coast of Florida and off Texas).

Within the EEZ, the U.S. has

• sovereign rights for the purpose of exploring, exploiting, conserving and managing natural resources, whether living and nonliving, of the seabed and subsoil and the superjacent waters and with regard to other activities for the economic exploitation and exploration of the zone, such as the production of energy from the water, currents and winds;
• jurisdiction as provided for in international law with regard to the establishment and use of artificial islands, installations, and structures, marine scientific research, and the protection and preservation of the marine environment, and
• other rights and duties provided for under international law (Presidential Proclamation No. 5030 of March 10, 1983).

For more information:
Office of Coast Survey
Download EEZ Limits

While we often think of the earth as a sphere, our planet is actually very bumpy and irregular.

The radius at the equator is larger than at the poles due to the long-term effects of the earth's rotation.  And, at a smaller scale, there is topography—mountains have more mass than a valley and thus the pull of gravity is regionally stronger near mountains.

All of these large and small variations to the size, shape, and mass distribution of the earth cause slight variations in the acceleration of gravity (or the "strength" of gravity's pull). These variations determine the shape of the planet's liquid environment.

If one were to remove the tides and currents from the ocean, it would settle onto a smoothly undulating shape (rising where gravity is high, sinking where gravity is low).

This irregular shape is called "the geoid," a surface which defines zero elevation. Using complex math and gravity readings on land, surveyors extend this
imaginary line through the continents. This model
is used to measure surface elevations with a high
degree of accuracy.

For more information:
National Geodetic Survey
National Spatial Reference System
NGS Geoid information
Diving Deeper Podcast, What is geodesy?

Part of each station is a recorder which sends an audio signal down a half-inch-wide sounding tube and measures the time it takes for the reflected signal to travel back from the water's surface.

In addition to measuring tidal heights, these stations also record 11 different oceanographic and meteorological parameters including wind speed and direction, water current speed and direction, air and water temperature, and barometric pressure.

For more information:
Center for Operational Oceanographic Products and Services
Measuring Tides (Diving Deeper podcast, 6.16.10)

NOAA's navigation response teams, part of the Office of Coast Survey, conduct hydrographic surveys of the ocean floor, monitoring for changes in depth or hazards below the surface of the water that could pose great danger to vessel traffic above.

For more information:
Office of Coast Survey
Navigation Response Teams (Diving Deeper podcast, 5.19.10)
Hydrographic Surveying
NOAA's Navigation Response Teams
Rapid Response for Disasters

In the beginning, the primeval seas were probably only slightly salty. But over time, as rain fell to the Earth and ran over the land, breaking up rocks and transporting their minerals to the ocean, the ocean has become saltier.

Rain replenishes freshwater in rivers and streams, so they don’t taste salty. However, the water in the ocean collects all of the salt and minerals from all of the rivers that flow into it.

It is estimated that the rivers and streams flowing from the United States alone discharge 225 million tons of dissolved solids and 513 million tons of suspended sediment annually to the ocean. Throughout the world, rivers carry an estimated four billion tons of dissolved salts to the ocean annually.

About the same tonnage of salt from ocean water probably is deposited as sediment on the ocean bottom and thus, yearly gains may offset yearly losses. In other words, the ocean today probably has a balanced salt input and output (and so the ocean is no longer getting saltier).

For more information:
Why is the ocean salty?
Salinity Data, National Oceanographic Data Center (NODC)

People use the terms dolphins, porpoises, and whales to describe marine mammals belonging to the order Cetacea (from the Greek work ketos, “large sea creature”), and often use them interchangeably. The orca, or killer whale, for example, is actually the largest member of the dolphin family.

Dolphins are by far more prevalent than porpoises. Most scientists agree that there are 32 dolphin species (plus five closely related species of river dolphin) and only six porpoise species.

So what’s the difference? It essentially comes down to their faces (who can forget Flipper’s famous “grin”?), their fins, and their figures. Dolphins tend to have prominent, elongated “beaks” and cone-shaped teeth, while porpoises have smaller mouths and spade-shaped teeth. The dolphin’s hooked or curved dorsal fin (the one in the middle of the animal’s back) also differs from the porpoise’s triangular dorsal fin. Generally speaking, dolphin bodies are leaner, and porpoises’ are portly.

Dolphins are also more talkative than porpoises. Dolphins make whistling sounds through their blowholes to communicate with one another underwater. Scientists are pretty sure that porpoises do not do this, and some think this may be due to structural differences in the porpoise’s blowhole.

Dolphins and porpoises have many similarities, one of which is their extreme intelligence. Both have large, complex brains and a structure in their foreheads, called the melon, with which they generate sonar (sound waves) to navigate their underwater world.

It is likely that more (or fewer) differences between dolphins and porpoises will be revealed as researchers continue to investigate these intriguing sentinels of the sea.

For more information
Cetaceans: Whales, Dolphins, and Porpoises, NOAA Fisheries Office of Protected Resources
Marine Mammals, NOAA Fisheries Office of Protected Resources

The NOS Marine Forensics Program is the only laboratory in the country dedicated to the forensic analysis of marine species.

The group'€™s mission began in the 1970s when congress passed a series of acts that protect fisheries, marine mammals, and endangered species. The problem then arose of how to enforce these new laws. Without the fins, scales, and heads attached, it was impossible for NOAA agents to tell if the samples they came across were from regulated species.

Today, the Marine Forensics Program is called upon to analyze evidence in 85 percent of NOAA fisheries cases when scientific analysis is needed. Here are some examples:

— Sea turtles and whales are still slaughtered today for food, cosmetic, medicinal, and decorative use despite many laws that aim to prohibit this activity. The NOS team analyzes DNA samples to identify the species and even trace evidence such as blood stains on a boat deck.

— Shark fins are valuable for shark fin soup. While shark finning is illegal in the U.S., this practice still continues abroad. Using DNA, scientists can determine what species of shark was finned, helping to enforce laws designed to protect fisheries resources.

— False labeling of imported species harms consumers and the domestic fishermen who strive to collect high-quality seafood. Marine forensic analysts use DNA analysis to identify fish fillet samples to determine if they are incorrectly labeled or if they are from a protected species.

Most of the lab's work involves using DNA sequencing to identify the exact species of a suspect sample of fish or meat provided by NOAA law enforcement agents. Sample quality can range from freshly frozen fish fillets to peices of bone. The lab maintains samples from hundreds of marine species, totaling more than 10,000 samples, as "standards" to compare with evidence.

NOAA's marine forensic scientists also participate in many national meetings to share their expertise with other agencies and federal prosecutors. Successful prosecutions of those who violate federal wildlife laws help to prevent further decline of valuable wildlife resources.

For more information
NOS Marine Forensics Program
National Centers for Coastal Ocean Science
NOAA Fisheries Office of Protected Resources
NOAA Office of Law Enforcement

Invasive species can harm both the natural resources in an ecosystem as well as threaten human use of these resources. An invasive species can be introduced to a new area via the ballast water of oceangoing ships, intentional and accidental releases of aquaculture species, aquarium specimens or bait, and other means.

Invasive species are capable of causing extinctions of native plants and animals, reducing biodiversity, competing with native organisms for limited resources, and altering habitats. This can result in huge economic impacts and fundamental disruptions of coastal and Great Lakes ecosystems.

For more information:
National Centers for Coastal Ocean Science
Episode 14 (Making Waves podcast, 1.30.09)
Invasive Lionfish
Zebra Mussel
Aquatic Invasive Species

The right whale is the most endangered species of whale off the coast of the United States. It was the first whale hunted by American whalers, and it was so depleted that it has not recovered despite being protected for over 50 years.

Adult right whales are generally between 45 and 55 feet (13.7-16.7 meters) in length and can weigh up to 70 tons (63,500 kilograms). Females right whales are larger than males. Like many whales, right whales feed on schools of small, shrimp-like crustaceans. They may also eat small fish near the ocean floor.

North Atlantic right whales inhabit the Atlantic Ocean, particularly between 20° and 60° latitude. It is believed that about 300-400 individual right whales live in the western North Atlantic, while the population in the eastern North Atlantic is probably only numbering in the low tens of animals. These whales are thus listed as endangered species under the Endangered Species Act.

Ship collisions and entanglement in fishing gear are the most common human causes of serious injury and mortality of western North Atlantic right whales today. NOAA’s National Marine Fisheries Service has taken steps to reduce the threat of ship collisions and gear entanglement.

For more information:
North Atlantic Right Whales
National Marine Fisheries Service Office of Protected Resources
Northern Right Whale Early Warning System

As there is no reference that designates one specific shoreline as the “legal” shoreline, numbers for the length of the U.S. shoreline can vary depending on how the shoreline is defined. 

The NOAA figure was determined by hand in 1939-40 with a recording instrument on the largest-scale charts and maps available at that time. Shorelines of outer coast, offshore islands, sounds, bays, rivers, and creeks were included to the head of the tidewater or to a point where tidal waters narrow to a width of 100 feet. For the Great Lakes, the shoreline lengths were measured in 1970 by the International Coordinating Committee on Great Lakes Basic Hydraulic and Hydrologic Data.

The total length of tidal shoreline includes measurements of the coastal states as well as the outlying U.S. territories and possessions.

For more information:
NOAA Shoreline Website
The Coastline of the United States (pdf, 305kb)

The Chesapeake Bay is the largest estuary in the United States and is one of the most productive bodies of water in the world.

The Chesapeake watershed* spans 64,000 squares miles, covering parts of six states — Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia, and the District of Columbia. Over 17 million people live in this area.

(*A watershed is the area of land where all of the water that is under it or drains off of it goes into the same place.)

The estuary and its network of streams, creeks and rivers hold tremendous ecological, cultural, economic, historic, and recreational value for the region.

More than 250 fish species use the Bay and tributaries for some portion of their life cycles, including American and hickory shad, river herring, striped bass, eel, weakfish, bluefish, flounder, oysters, and blue crabs. More than 300 migratory bird species can also be found in the watershed. During the fall, the skies come alive as one million ducks, geese, and swans return to overwinter on the Chesapeake.

The Chesapeake watershed is a complex network of wetlands, forests, fields, streams, underwater grasses, and mudflats that provide thousands of species of plants, fish, and wildlife with the places they need to find food, shelter, reproduce, and rear their young. The Chesapeake also provides "habitat highways" for Atlantic Coast fish populations and birds migrating along the Atlantic Flyway. These habitats play an important role in filtering pollution before it enters waterways.

Bay wetlands serve as holding tanks and water filters for coastal storm surge and heavy rainfall and help prevent costly flood damage. Forest buffers along streams and shorelines provide shade to keep streams cool, food for aquatic organisms and corridors for wildlife movement. Streams are the arteries that connect the watershed and provide not only passage for fish, but also a physical connection from every local community to the Bay.

Today, the Bay and its tributaries are in poor health, with polluted water, low populations of fish and shellfish, degraded habitats, and landscapes lost to development. In recognition of this, President Obama issued an Executive Order in 2009 to protect and restore this important area. In the Order, the President declared the Chesapeake Bay a "national treasure" and ushered in a new era of federal leadership, action and accountability to "protect and restore the health, heritage, natural resources, and social and economic value of the nation's largest estuarine ecosystem and the natural sustainability of its watershed."

For more information:
Estuaries.Gov
National Estuarine Research Reserve System
Estuaries, NOS Education
NOAA Chesapeake Bay Office
Cooperative Oxford Laboratory
Executive Order 13508: Strategy for Protecting and Restoring the Chesapeake Bay Watershed
Interview with the director of the Cooperative Oxford Lab
Chesapeake Eco-check

The ocean is a huge body of water that is constantly in motion. General patterns of ocean flow are called currents. Sometimes theses currents can pinch off sections and create circular currents of water called an eddy.

You may have seen an eddy if you've ever gone canoeing and you see a small whirlpool of water while you paddle through the water. The swirling motion of eddies in the ocean cause nutrients that are normally found in colder, deeper waters to come to the surface.

Significant eddies are assigned names similar to hurricanes. In the U.S., an oceanographic company called Horizon Marine assigns names to each eddy as they occur. The names follow chronologically along with the alphabet and are decided upon by staff at Horizon Marine. The staff try to think of creative ways to assign names.

For example, an eddy that formed in the Gulf of Mexico in June 2010 is named Eddy Franklin after Ben Franklin, as he was known to have done research on the Gulf Stream.

For more information:
Ocean Mesoscale Eddies, NOAA's Geophysical Fluid Dynamics Laboratory
Center for Operational Oceanographic Products and Services
National Current Observation Program
Currents Tutorial, NOS Education
Diving Deeper Podcast, Episode 15 (August 12, 2009) - What are currents?
Horizon Marine

Hurricanes, cyclones, and typhoons are all the same weather phenomenon; we just use different names for these storms in different places. In the Atlantic and Northeast Pacific, the term “hurricane” is used. The same type of disturbance in the Northwest Pacific is called a “typhoon” and “cyclones” occur in the South Pacific and Indian Ocean.

The ingredients for these storms include a pre-existing weather disturbance, warm tropical oceans, moisture, and relatively light winds. If the right conditions persist long enough, they can combine to produce the violent winds, incredible waves, torrential rains, and floods we associate with this phenomenon.

In the Atlantic, hurricane season officially runs June 1 to November 30. However, while 97 percent of tropical activity occurs during this time period, there is nothing magical in these dates, and hurricanes have occurred outside of these six months.

For more information:
Hurricane Basics, National Hurricane Center
What is a hurricane, typhoon, or tropical cyclone? Atlantic Oceanographic and Meteorological Laboratory
Hurricane Season Begins, Making Waves [audio podcast]

Weighing in at between 550 and 2,000 pounds (250 to 907 kilograms) with lengths of up to six feet, the leatherback is a big turtle! Leatherback sea turtles can be distinguished from other species of sea turtle by its lack of a hard shell or scales. Instead, leatherbacks are covered with a firm, rubbery skin.

You can find leatherback sea turtles as far north as Canada and the northern Pacific Ocean. They tend to nest in the tropics, however. Within the United States, the leatherback is known to nest in southeast Florida, Puerto Rico, and the U.S. Virgin Islands.

The leatherback sea turtle feeds primarily on jellyfish.

The U.S. federal government has listed the leatherback as endangered worldwide. Primary threats to the turtles include incidental take in commercial fisheries and marine pollution, as well as the harvest of eggs.

For more information:
Leatherback Turtle, National Marine Fisheries Service
Northeast Fisheries Science Center Fish FAQ

With predicted, real-time, and forecasted currents, people can safely dock and undock ships, maneuver them in confined waterways, and safely navigate through coastal waters. This helps to avoid ship collisions or delay the arrival of goods.

In addition, current measurements are important for search and rescue operations, environmental disasters, and coastal engineering projects.

When supporting search and rescue operations, understanding the speed and direction of the currents in an area helps to narrow down the rescue and recovery effort. Current prediction information can help scientists clean up after a hazardous oil spill by helping them understand the direction and movement of the oil. Engineers also use currents information to help build marine structures such as bridges or docks and piers.

Current observations are also used to develop and evaluate coastal nowcast or forecast model products that are provided online.

For more information:
Center for Operational Oceanographic Products and Services
Currents (Diving Deeper podcast, 8.12.09)
NOS Education: Currents Tutorial
Tides (Diving Deeper podcast, 4.8.09)
NOS Education: Tides Tutorial

Waterspouts fall into two categories: fair weather waterspouts and tornadic waterspouts.

Tornadic waterspouts are tornadoes that form over water, or move from land to water. They have the same characteristics as a land tornado. They are associated with severe thunderstorms, and are often accompanied by high winds and seas, large hail, and frequent dangerous lightning.

Fair weather waterspouts usually form along the dark flat base of a line of developing cumulus clouds. This type of waterspout is generally not associated with thunderstorms. While tornadic waterspouts develop downward in a thunderstorm, a fair weather waterspout develops on the surface of the water and works its way upward. By the time the funnel is visible, a fair weather waterspout is near maturity. Fair weather waterspouts form in light wind conditions so they normally move very little.

If a waterspout moves onshore, the National Weather Service issues a tornado warning, as some of them can cause significant damage and injuries to people. Typically, fair weather waterspouts dissipate rapidly when they make landfall, and rarely penetrate far inland.

For more information:
What is a waterspout?, NOAA's National Weather Center
Waterspout video, Ocean Today Kiosk network

In 1970, NOAA was officially recognized and all of its components were united under a common name and mission. One year later, NOAA's first administrator, Dr. Robert White, gave NOAA employees the choice of three designs to be the official emblem for the new agency.

The chosen design was made the official NOAA emblem later that year and remains the official emblem of the agency to this day.

About the winning design, Dr. White remarked that: "A white, gull-like form links the atmosphere to the sea or Earth. The Earth and atmosphere and the interrelationships between the two are, of course, major concerns of NOAA. The line defining the top of the gull's wings also resemble the trough of a foaming ocean wave against the blue sky. A creature of sea, land, and air, the gull adds an ecological touch to the Earth-sky motif."

For more information:
NOAA Emblem, NOAA 200th Anniversary Web site

The loop current is an area of warm water that travels up from the Caribbean, past the Yucatan Peninsula, and into the Gulf of Mexico. The current is also known as the Florida current as it flows through the Florida Strait, into the Gulf Stream, and heads north up the eastern coast of the U.S.

From the south, the Gulf of Mexico is fed by a current of warm water from the Caribbean, which enters the Gulf between Mexico's Yucatan Peninsula and Cuba. This forms the Gulf Loop Current, which curves east and south along Florida's coast and exits through the Straits of Florida.

The Gulf Loop is variable. Sometimes, the current barely enters the Gulf of Mexico before heading towards the Atlantic. At other times, it may travel nearly to the coast of Louisiana before swinging back towards the Florida Strait.

For more information:
Center for Operational Oceanographic Products and Services
National Current Observation Program
Diving Deeper Podcast, Episode15 (August 12, 2009) - What are currents?
Currents Tutorial, NOS Education

Seamounts — undersea mountains formed by volcanic activity — were once thought to be little more than hazards to submarine navigation. Today, scientists recognize these structures as biological hotspots that support a dazzling array of marine life.

The biological richness of seamount habitats results from the shape of these undersea mountains. Thanks to the steep slopes of seamounts, nutrients are carried upwards from the depths of the oceans toward the sunlit surface, providing food for creatures ranging from corals to fish to crustaceans.

New estimates suggest that, taken together, seamounts encompass about 28.8 million square kilometers of the Earth's surface. That's larger than deserts, tundra, or any other single land-based global habitat on the planet.

For more information
Center for Coastal Environmental Health and Biomolecular Research
National Centers for Coastal Ocean Science
New Report Revises Estimate of Worldwide Seamount Distribution (NOS News, May 2010)
The Hidden World of Seamounts (Making Waves podcast, 5.13.10)
Seamount Fly-Through (YouTube video)

Penguins are birds, so they do have wings. However, the wing structures of penguins are evolved for swimming, rather than flying in the traditional sense. Penguins do “fly” underwater at speeds of up to 15 to 25 miles per hour.

As adept swimmers, penguins spend a lot of time in the water. Some penguins spend up to 75 percent of their lives in the water. Like other birds, penguins do lay eggs and they raise their chicks on land.

All penguins live in the Southern Hemisphere.

For more information:
Penguin Adaptation, NASA QUEST
Seabird Research Program, Southwest Fisheries Science Center
Arctic & Antarctic Activity Book (pdf)

Oil destroys the insulating ability of fur-bearing mammals, such as sea otters, and the water-repelling abilities of a bird's feathers, thus exposing these creatures to the harsh elements. Without the ability to repel water and insulate from the cold water, birds and mammals will die from hypothermia.

Many birds and animals also ingest oil when they try to clean themselves, which can poison them.

For more information:
Office of Response and Restoration
Oil Spill Response (Diving Deeper podcast, 4.7.10)
Spill of National Significance - Preparing for Oil Spill Disasters
Oil in the Ocean
Explore: Oil and Chemical Spills
Oil Spills: Learn More
Effects of Oil Spills on Wildlife and Habitat (pdf),U.S. Fish and Wildlife Service Alaska Region

Debris found in this area can easily be ingested by marine species causing choking, starvation, and other impairments.

Because there has been little scientific research conducted in this area, the exact size, content, and location of the garbage patch are difficult to accurately predict. Marine debris concentrates in various areas of the North Pacific – not just the garbage patch.

It appears that the garbage patch referred to in the media is within the North Pacific Subtropical High, an area between Hawaii and California. The North Pacific Subtropical High is not a stationary area, but one that moves and changes. This area is defined by the NOAA National Weather Service as “a semi-permanent, subtropical area of high pressure in the North Pacific Ocean.”

For more information:
NOAA Marine Debris Program
Marine Debris (Diving Deeper podcast, 2.23.09)

Bathymetric data, which includes information about the depths and shapes of underwater terrain, has a range of uses, including:

• Bathymetric surveys provide the data on which nautical charts are based.  These charts guide mariners much as road maps guide motorists, ensuring safe and efficient maritime transportation.
• Bathymetric maps are becoming increasingly important as scientists seek to learn more about the effects of climate change on the environment. Bathymetric surveys can alert scientists to ongoing and potential beach erosion, landslides, sea-level rise, and subsidence (land sinking). Scientists also need current/updated bathymetric survey data, which is critical to support the creation and development of hydrodynamic models.
• Bathymetry is also a key element of biological oceanography.  The depth and characteristics of the seabed define the habitat for benthic (bottom-dwelling) organisms, and are fundamental parameters of marine ecosystems.  Scientists increasingly rely on high-resolution bathymetry in their efforts to determine where fish and other sea life will feed, live, and breed.

For more information:
Office of Coast Survey
Sea-floor Mapping, NOS Education

National marine sanctuary staff conduct research and use that science to better understand the marine environment at all 14 sanctuary sites. This knowledge is necessary to establish an effective strategy for protection.

Public education and appreciation for marine resources is needed for protection. Education programs exist at all sanctuary sites. An educated public understands how to interact in the environment to avoid damaging marine resources and will help to promote the main conservation messages.

The sanctuaries also implement a permit system to regulate and oversee potentially harmful activities in sanctuaries. This framework may be enhanced by the adoption of state and other federal laws and regulations.

Another important tool is “interpretive enforcement,” emphasizing education about responsible behavior as a proactive method to prevent harmful resource impacts from occurring in the first place.

The National Marine Sanctuaries Act, along with site-specific legislation and regulations, provides the legal framework outlining the activities that are allowed or prohibited.

For more information:
Office of National Marine Sanctuaries
Diving Deeper Podcast, Episode 8 (May 6, 2009): National Marine Sanctuaries
National Marine Sanctuaries Act

Warmer water temperatures can result in coral bleaching. When water is too warm, corals will expel the algae (zooxanthellae) living in their tissues causing the coral to turn completely white. This is called coral bleaching. When a coral bleaches, it is not dead. Corals can survive a bleaching event, but they are under more stress and are subject to mortality.

In 2005, the U.S. lost half of its coral reefs in the Caribbean in one year due to a massive bleaching event. The warm waters centered around the northern Antilles near the Virgin Islands and Puerto Rico expanded southward. Comparison of satellite data from the previous 20 years confirmed that thermal stress from the 2005 event was greater than the previous 20 years combined.

Not all bleaching events are due to warm water.

In January 2010, cold water temperatures in the Florida Keys caused a coral bleaching event that resulted in some coral death. Water temperatures dropped -6.7 degrees Celsius (20 degrees Fahrenheit) lower than the typical temperatures observed at this time of year. Researchers will evaluate if this cold-stress event will make corals more susceptible to disease in the same way that warmer waters impact corals.

For more information :
Coral Reef Conservation Program
Coral Reef Information System
Diving Deeper Podcast, Episode 20 (February 24, 2010):Why are coral reefs valuable?
First Florida Cold-water Bleaching Event in 30 Years
Corals, NOS Education

Even though they live in the ocean all of the time, dolphins are mammals, not fish.

Like every mammal, dolphins are warm blooded. Unlike fish, who breathe through gills, dolphins breathe air using lungs. Dolphins must make frequent trips to the surface of the water to catch a breath. The blowhole on top of a dolphin's head acts as a "nose," making it easy for the dolphin to surface for air.

Other characteristics of dolphins that make them mammals rather than fish are that they give birth to live young rather than laying eggs and they feed their young with milk. Also, like all mammals, dolphins even have a tiny amount of hair, right around the blowhole, which is a little different than the scales of a fish.

Whales and porpoises are also mammals. There are 75 species of dolphins, whales, and porpoises living in the ocean. They are the only mammals, other than manatees, that spend their entire lives in the water.

For more information:
Cetaceans: Whales, Dolphins, and Porpoises, NOAA Fisheries Office of Protected Resources
Marine Mammals, NOAA Fisheries Office of Protected Resources
Whales and Dolphins, Gray's Reef National Marine Sanctuary

The term “bathymetry” originally referred to the ocean’s depth relative to sea level, although it has come to mean “submarine topography,” or the depths and shapes of underwater terrain.

In the same way that topographic maps represent the three-dimensional features (or relief) of overland terrain, bathymetric maps illustrate the land that lies underwater. Variations in sea-floor relief may be depicted by color and contour lines called depth contours or isobaths.

Bathymetry is the foundation of the science of hydrography, which measures the physical features of a water body.  Hydrography includes not only bathymetry, but also the shape and features of the shoreline; the characteristics of tides, currents, and waves; and the physical and chemical properties of the water itself.

For more information:
Office of Coast Survey
Sea-floor Mapping, NOS Education

Geodesists assign coordinates to points all over the Earth. Using the Global Positioning System (GPS), geodesists can accurately define the coordinates of points on the surface of the Earth in a consistent manner. This set of accurately measured points is called the National Spatial Reference System (NSRS), which allows different kinds of maps to be consistent with one another.

Developers, local officials, city planners, and many others use the National Spatial Reference System to determine land boundaries for development or conservation efforts. Government agencies also rely on the NSRS to update maps of the U.S. shoreline.

Geodesy is also critical to the transportation industry. Surveyors use the National Spatial Reference System as one of their tools to develop nautical charts. Mariners use these nautical charts and GPS to accurately position their ships. This technology, accurate down to a centimeter scale, allows mariners and commercial vessels to assess where the bottoms of their ships are relative to the bottom of the ocean. With this information, a ship can hold extra cargo, sinking deeper into the water, and still safely navigate through a channel. The ability to move more cargo at a time is direct economic benefit to the shipping industries and ultimately to the consumer.

In addition, geodetic data, specifically datum information, and water level data are critical for agency officials to properly plan, design, and engineer coastal restoration projects. These data provide baseline information that assist in the construction of phases of marsh restoration projects, for example.

Geodesy is the science of measuring and monitoring the size and shape of the Earth, including its gravity field, and determining the location of points on the Earth’s surface.

For more information:
National Geodetic Survey
National Spatial Reference System
Diving Deeper Podcast, Episode 9 (May 20, 2009) -- What is geodesy?
Geodesy Tutorial, NOS Education

The amount of time that it takes chemicals such as PCBs to breakdown naturally depends on their size, structure, and chemical composition. It can take years to remove these chemicals from the environment and that is why they are still present decades after they have been banned.

There are cleanup alternatives for chemicals in the environment, but this often requires considerable evaluation. Because PCBs exist in sediments, scientists need to determine if it is better to dredge and remove contaminated sediments from waterways or if it is safer to leave the sediments in place and cover with clean sediments, allowing them to naturally biodegrade. A cap or barrier can also be placed over contaminated sediments to prevent them from entering the environment. There are environmental, human health, and financial concerns with all of these alternatives.

PCBs are industrial products or chemicals that were used starting in the 1920s and until their ban in 1979. From the 1920s until their ban, an estimated 1.5 billion pounds of PCBs were made for things such as microscope oils, electrical insulators, capacitors, and electric appliances such as televisions or refrigerators.

For more information:
Office of Response and Restoration
Diving Deeper Podcast, Episode 11 (June 17, 2009) - What are PCBs?

The light emitted by a bioluminescent organism is produced by energy released from chemical reactions occurring inside (or ejected by) the organism.

If you’ve ever seen a firefly, you have encountered a bioluminescent organism. In the ocean, bioluminescence is not as rare as you might think. In fact, most types of animals, from bacteria to sharks, include some bioluminescent members. Also, bioluminescent are found throughout marine habitats, from the ocean surface to the deep sea floor.

While the functions of bioluminescence are not known for all animals, typically bioluminescence is used to warn or evade predators), to lure or detect prey, for communication between members of the same species.

For more information:
Bioluminescence, NOAA Ocean Explorer
Visual Ecology and Bioluminescence, NOAA Ocean Explorer
Deep Light, NOAA Ocean Explorer

Storm surge is the water that is pushed toward the shoreline by the force of winds from a hurricane or other intense storm. When combined with normal tides, the surge can create water levels 15 feet or more about the mean water level. This rise in water can cause severe flooding in coastal areas.

A tidal wave is a shallow water wave caused by the gravitational interactions between the Sun, Moon, and Earth. The term “tidal wave” is often used to refer to tsunamis; however, this reference is incorrect as tsunamis have nothing to do with tides.

For more information:
Storm Surge, National Hurricane Center
Center for Operational Oceanographic Products and Services

There are many things you may encounter when swimming in the ocean. Alligators probably aren’t one of them.

While alligators can tolerate salt water for a few hours or even days, they are primarily freshwater animals, living in swampy areas, rivers, streams, lakes, and ponds.

For more information:
Alligator, U.S. Geological Survey Southern Florida Information Access
American Alligator, U.S. Fish and Wildlife Service

Most people are surprised to learn that, just as the surface of the Earth is not flat, the surface of the ocean is not flat, and that the surface of the sea changes at different rates around the globe. For instance, the absolute water level height is higher along the West Coast of the United States than the East Coast.

You may have heard the term “global sea level,” which refers to the average height of all of the Earth’s ocean basins. “Global sea level rise” refers to the increase in the average global sea level trend.

“Local sea level” refers to the height of the water measured along the coast relative to a specific point on land. Tide stations measure local sea level. “Relative sea level trends” reflect changes in local sea level over time. This relative change is the one most critical for many coastal applications, including coastal mapping, marine boundary delineation, coastal zone management, coastal engineering, sustainable habitat restoration design, and the general public enjoying their favorite beach.

For more information:
Sea Levels Online, Center for Operational Oceanographic Products and Services

NOAA orchestrates the collection of ocean data through a federal, regional, and private-sector partnership called the U.S. Integrated Ocean Observing System, or IOOS®. This system helps the nation track, predict, manage, and adapt to changes in our marine environment.

IOOS data are increasing our understanding of how oceans drive storms to allow meteorologists to develop earlier, more accurate weather predictions. Store managers use these forecasts to decide whether to stock hurricane supplies or beach towels in their stores. Fishermen typically use weather and water data to make informed decisions about when it is safe to head to sea.

Through state-of-the-art high frequency radar systems and other technologies, IOOS scientists can also track ocean currents in near real time. By improving our ability to monitor the speed and direction of surface currents, search and rescue crews can track the probable path of people lost at sea and expedite recovery time.

For more information:

NOAA Integrated Ocean Observing System Program
Diving Deeper Podcast, Episode 2 (Mar. 9, 2009) - What is IOOS?

For decades, the Atlantic Ocean’s fabled Bermuda Triangle has captured the human imagination with unexplained disappearances of ships, planes, and people.

Some speculate that unknown and mysterious forces account for the unexplained disappearances, such as extraterrestrials capturing humans for study; the influence of the lost continent of Atlantis; vortices that suck objects into other dimensions; and other whimsical ideas.  Some explanations are more grounded in science, if not in evidence.  These include oceanic flatulence (methane gas erupting from ocean sediments) and disruptions in geomagnetic lines of flux.

Environmental considerations could explain many, if not most, of the disappearances.  The majority of Atlantic tropical storms and hurricanes pass through the Bermuda Triangle, and in the days prior to improved weather forecasting, these dangerous storms claimed many ships.  Also, the Gulf Stream can cause rapid, sometimes violent, changes in weather.  Additionally, the large number of islands in the Caribbean Sea creates many areas of shallow water that can be treacherous to ship navigation. And there is some evidence to suggest that the Bermuda Triangle is a place where a “magnetic” compass sometimes points towards “true” north, as opposed to “magnetic” north. 

The U.S. Navy and U.S. Coast Guard contend that there are no supernatural explanations for disasters at sea.  Their experience suggests that the combined forces of nature and human fallibility outdo even the most incredulous science fiction. They add that no official maps exist that delineate the boundaries of the Bermuda Triangle. The U. S. Board of Geographic Names does not recognize the Bermuda Triangle as an official name and does not maintain an official file on the area.

The ocean has always been a mysterious place to humans, and when foul weather or poor navigation is involved, it can be a very deadly place.  This is true all over the world.  There is no evidence that mysterious disappearances occur with any greater frequency in the Bermuda Triangle than in any other large, well-traveled area of the ocean. 

For more information:
Does the Bermuda Triangle really exist? – U.S. Coast Guard
Bermuda Triangle, U.S. Geological Survey

NOAA’s National Geodetic Survey (NGS) defines and maintains the NSRS. The NSRS includes a network of permanently marked points; a consistent, accurate, and up-to-date national shoreline; a network of Continuously Operating Reference Stations (CORS) which supports three-dimensional positioning activities; and a set of accurate models describing dynamic, geophysical processes that affect spatial measurements.

For over 200 years, NGS and its predecessor agencies have collaborated with surveyors in both the public and private sectors to place hundreds of thousands of survey marks throughout the United States, determining positional information for each mark. Each survey mark is published with accurate horizontal and/or vertical information such as latitude, longitude, and/or height. Typically, a mark is a brass, bronze, or aluminum disk, but it might also be a deeply driven rod or prominent object like a water tower or church spire. Increasingly, the continuously operating global positioning system receivers of CORS stations are used as reference stations as well.

This collection of points (over 1,500,000 of them) forms a network that is used to accurately position other points of interest. Surveyors and others use the NSRS throughout the country to ensure that their positional coordinates are compatible with those determined by others. In this way, when they create maps; mark off property boundaries; and plan, design, and build roads, bridges, and other structures, everything matches up.

For more information:
National Geodetic Survey

The National Spatial Reference System: Fundamental Data for Land Surveys, Nautical Charts, and the Nation's Infrastructure

Of the three percent of the water that is not in the ocean, about 69 percent is locked up in glaciers and icecaps. Ninety percent of that frozen water is in Antarctica and about nine percent covers Greenland.

Of the remaining freshwater, 30 percent of it is groundwater, captured below our feet. About 0.3 percent is found in rivers and lakes. This means that the water source we are most familiar with in our everyday lives, rivers and lakes, accounts for less than one percent of all freshwater that exists on Earth.

A very small percentage of water (0.1 percent of all water) is also found in the atmosphere.

For more information:
The Ocean’s Role in Weather and Climate, NOS Education
The Hydrologic Cycle, National Weather Service Northwest River Forecast Center

The Coastal Zone Management Act (CZMA), passed in 1972 and administered by the Office of Ocean and Coastal Resource Management, provides for the management of the nation’s coastal resources by balancing economic development with environmental conservation. The goal of the CZMA is to “preserve, protect, develop, and where possible, to restore or enhance the resources of the nation's coastal zone."

The CZMA applies to many different federal actions including federal agency activities, federal license or permit activities, outer continental shelf plans, and federally assisted state projects.

In order to ensure federal consistency, a state agency reviews any programs being implemented by the federal government. Along with the state review, the National Ocean Service interprets the CZMA, oversees applications of federal consistency, provides management and legal assistance to coastal states and federal agencies, and mediates CZMA-related disputes.

The CZMA promotes cooperation and coordination between state s and the federal government in order to promote federal consistency and protect our nation’s coastal resources.

For more information:
CZMA: Federal Consistency Overview (pdf, 200kb)
Federal Consistency Overview
Congressional Action to Help Manage Our Nation's Coasts
Explore: Coastal Zone Management

With an area of about 5.4 million square miles, the Arctic Ocean is about 1.5 times as big as the United States. It is bordered by Greenland, Canada, Norway, Alaska, and Russia. The average depth of the Arctic Ocean is 12,000 feet and it is 17,850 feet at its deepest point.

The Arctic Ocean is almost completely covered with ice for the majority of the year and its average temperature seldom rises above freezing. However, this ocean is anything but barren.

Tunnels within sea ice called brine channels house bacteria and algae that feed flatworms and other tunnel-dwelling creatures. Melting ice also forms ponds on top of the ice that develop into biological communities.

When the ice melts, organisms and nutrients are released into the water. This promotes algae growth below the ice. These algae provide food for small organisms called zooplankton, which are a food source for fish, squid, seals, and whales. Some of these larger creatures, in turn, are preyed upon by polar bears that live on the ice.

When the creatures below the ice die, they sink to the bottom of the ocean and provide nutrients for sponges, sea anemones, and other bottom dwelling creatures. When these communities grow, they provide food once again for larger creatures such as seals, fish, and whales.

For more information:
What is the largest ocean basin on Earth?
How many oceans are there?
Russian-U.S. Arctic Census – NOAA Ocean Explorer
Frequently Asked Questions about the Arctic – NOAA Arctic Theme Page

Whales are very social creatures that travel in groups called “pods.” They use a variety of noises to communicate and socialize with each other. The three main types of sounds made by whales are clicks, whistles, and pulsed calls.

Clicks are believed to be for navigation and identifying physical surroundings. When the sound waves bounce off of an object, they return to the whale, allowing the whale to identify the shape of the object. Clicks can even help to differentiate between friendly creatures and predators. Clicks have also been observed during social interactions, suggesting they may also have a communicative function.

Whistles and pulsed calls are used during social activities. Pulsed calls are more frequent and sound like squeaks, screams, and squawks to the human ear. Differing vocal “dialects” have been found to exist between different pods within the same whale population. This is most likely so that whales can differentiate between whales within their pods and strangers.

Whales also use their tails and fins to make loud slapping noises on the surface of the water to communicate nonverbally. The sound can be heard for hundreds of meters below the surface and may be a warning sign of aggression or a tool to scare schools of fish together, making them an easier meal.

In the Stellwagen Bank National Marine Sanctuary, NOAA scientists attached sensors to whales in order to track their movement patterns. They hope to learn about the whales’ behavior and communication as well as to observe how human interaction affects their behavior.

For more information:
Killer Whales, National Marine Fisheries Service
Marine Mammal Sounds: Blue Whale, Vents Program Acoustic Monitoring

The most common type of reef is the fringing reef. This type of reef grows seaward directly from the shore. They form borders along the shoreline and surrounding islands.

When a fringing reef continues to grow upward from a volcanic island that has sunk entirely below sea level, an atoll is formed. Atolls are usually circular or oval in shape, with an open lagoon in the center.

Barrier reefs are similar to fringing reefs in that they also border a shoreline; however, instead of growing directly out from the shore, they are separated from land by an expanse of water. This creates a lagoon of open, often deep water between the reef and the shore.

Coral reefs are important because they bring in billions of dollars to our economy through tourism, protect coastal homes from storms, provide promising medical treatments, and provide a home for millions of aquatic species.

NOAA’s Coral Reef Conservation Program works to protect coral reefs through research, education, and preservation programs. Many reefs, such as the Virgin Islands Coral Reef National Monument, are housed in NOAA’s system of marine protected areas.

For more information:
What are Coral Reefs, NOAA’s Coral Reef Information System
NOAA’s Coral Reef Conservation Program
Explore: Coral Reef Conservation

The Papahānaumokuākea Marine National Monument is not only the largest conservation area in the U.S., it's one of the largest marine conservation areas in the world. It's larger than all of America’s national parks combined! This vast region preserves many of Hawaii’s Northwestern Islands and is made up of 139,797 square miles of reefs, atolls, shallow waters, and deep seas.

The monument contains a wide variety of critically important habitats that harbor over 7,000 marine species, several of which are only found in this region. It is also home to many rare and endangered species such as the green sea turtle and the Hawaiian monk seal.

The Papahānaumokuākea Marine National Monument is one of fourteen marine protected areas that form NOAA’s National Marine Sanctuary system. The goal of this system is to conserve, protect, and enhance the biodiversity, ecological integrity, and cultural legacy of marine areas totaling 150,000 square miles.

For more information:
Papahānaumokuākea Marine National Monument
Office of National Marine Sanctuaries
Diving Deeper Podcast, Episode 8 (May 6, 2009) - What is a national marine sanctuary?

In kelp forests, the most commonly found invertebrates are bristle worms, scud, prawn, snails, and brittle stars. These animals feed on the holdfasts that keep kelp anchored to the bottom of the ocean and algae that are abundant in kelp forests. Sea urchins will often completely remove kelp plants by eating through their holdfasts. Other invertebrates found in kelp forests are sea stars, anemones, crabs, and jellyfish.

A wide range of fish can be found in kelp forests, many of which are important to commercial fishermen. For example, many types of rockfish such as black rockfish, blue rockfish, olive rockfish, and kelp rockfish are found in kelp forests and are important to fishermen.

A wide range of marine mammals inhabit kelp forests for protection and food. Sea lions and seals feed on the fish that live in kelp forests. Grey whales have also been observed in kelp forests, most likely using the forest as a safe haven from the predatory killer whale. The grey whale will eat the abundant invertebrates and crustaceans in kelp forests. One of the most important mammals in a kelp forest is the sea otter, who takes refuge from sharks and storms in these forests. The sea otter eats the red sea urchin that can destroy a kelp forest if left to multiply freely.

Kelp forests are a natural buffet for birds such as crows, warblers, starlings, and black phoebes which feed on flies, maggots, and small crustaceans that are abundant in kelp forests. Gulls, terns, egrets, great blue herons, and cormorants dine on the many fish and invertebrates living in the kelp. Kelp forests also provide birds with a refuge from storms.

For more information:

Ecosystems: Kelp Forests, Office of National Marine Sanctuaries
Invertebrate and Vertebrate Assemblages Associated with Kelp Forests, Monterey Bay National Marine Sanctuary
Kelp Forest, Olympic Coast National Marine Sanctuary

Maritime heritage includes not only physical resources such as historic shipwrecks and prehistoric archaeological sites, but also archival documents and oral histories. Maritime heritage can also include the stories of indigenous cultures that have lived and used the oceans for thousands of years.

There is a maritime heritage component in each of our 13 national marine sanctuaries and our one national monument, whether this is a shipwreck or study of indigenous cultures. The first sanctuary that was created with a maritime heritage component was the Monitor National Marine Sanctuary off the coast of North Carolina in 1975.

Maritime heritage resources are studied through very careful recovery and in many cases, long-term conservation to preserve these artifacts in a museum for future generations.

Maritime heritage resources, when properly studied and interpreted, add an important dimension to our understanding and appreciation of our nation’s rich maritime legacy, and make us more aware of the critical need for us to be wise stewards of our ocean planet.

For more information:
Office of National Marine Sanctuaries: Maritime Heritage
Monitor National Marine Sanctuary
Diving Deeper Podcast, Episode 16 (September 9, 2009) - What is maritime heritage?

An observer stands on a ship, throws the drifter into the water, and then measures the time that it takes that object to move along the side of a ship. As technology improved over time, oceanographers began using mechanical current meters. A ship would deploy a meter and usually some sort of rotor would turn and measure the currents. This is still the basic process today; however there are more accurate and sophisticated instruments.

Today in the open ocean, a drifter is similar to a buoy in the water that may be equipped with global positioning system technology or satellite communications that would relay data and information. Drifters can also submerge for long periods of time to measure ocean currents at a particular depth. The drifter would then resurface occasionally to send a signal with its data and position to observers on the land.

In addition to buoys, there are other tools that are used to monitor currents. The Acoustic Doppler Current Profiler is commonly used to measure currents. It is normally deployed on the sea floor or attached to the bottom of a boat. It sends an acoustic signal into the water column and that sound bounces off particles in the water. The instrument can calculate the speed and direction of the current by knowing the frequency of the return signal, the distance it traveled, and the time it took for the signal to travel.

Many oceanographers also use radio antennas and high frequency Radio Detecting and Ranging systems (radar) to measure surface ocean currents. Similar to the Acoustic Doppler Current Profiler, these shore-based instruments use the Doppler effect to determine when currents are moving toward or away from the shore or to measure the velocity of a current.

At NOAA, oceanographers use knots to measure current speed. The term knot is defined as one nautical mile per hour. One nautical mile is equal to 1.85 kilometers (1.15 standard miles). One knot is also 51.44 centimeters per second (3.281 feet per minute).

For more information:
Center for Operational Oceanographic Products and Services
National Current Observation Program
Diving Deeper Podcast, Episode15 (August 12, 2009) - What are currents?
Currents Tutorial, NOS Education

The Monitor was the first of 14 marine protected areas that make up the National Marine Sanctuary System, which includes more than 388,498 square kilometers (150,000 square miles) of marine and Great Lakes waters. The sanctuary boundaries (2.59 square kilometers or 1 square mile) protect the wreck of the USS Monitor, which lies 25.75 kilometers (16 miles) southeast of Cape Hatteras, NC. Since its sinking in 1862, the Monitor has become a productive artificial reef.

While most of the research conducted in the Monitor sanctuary has focused on the archaeological documentation of the shipwreck, NOAA scientists are now interested in studying the water quality and marine environment of the wreck site. A NOAA data buoy installed in the sanctuary in 2006 is providing scientists and the public the opportunity to monitor weather and sea conditions 24 hours a day.

For more information:
Office of National Marine Sanctuaries
Monitor National Marine Sanctuary
Diving Deeper Podcast, Episode 8 (May 6, 2009) - What is a national marine sanctuary?
Diving Deeper Podcast, Episode 16 (September 9, 2009) - What is maritime heritage?

Losses from catastrophic events such as hurricanes can be extensive. The economic losses from the 2005 hurricane season, which included Hurricanes Katrina and Rita, were $200 billion, the costliest season ever.

For some threats, such as sea level rise, only the projected economic losses are indicated. For example, the vast majority of our nation’s commercial and recreational fisheries are dependent on coastal marshes. Approximately two-thirds of those fisheries spend some stage of their lives in tidal marshes. As sea levels rise, the built-up areas behind these marshes will provide no opportunities for wetlands to migrate. The net result will be billions of dollars in economic impacts affecting the livelihoods and sustainability of many coastal communities.

Coastal threats are different throughout the United States. For example, in the Pacific Islands, there are more potentially catastrophic coastal hazards such as tsunamis, flooding, and even droughts. In the North Atlantic, there are more severe storms, population and development pressures, and regional-scale impacts such as climate change.

It is critical to develop hazard-resilient communities to prepare for these threats and enhance the ability of these communities to absorb impacts and bounce back. This preparation will reduce the lives lost in disasters, secure the economic stability of these communities, and support the health of our coastal ecosystems, including wetlands which are essential for reducing storm impacts on our coastal communities.

For more information:
NOAA Coastal Services Center
Coastal Hazards, NOAA's Office of Ocean and Coastal Resource Management
Local Strategies for Addressing Climate Change (pdf, 1.12 mb)
Diving Deeper Podcast, Episode 10 (June 3, 2009) - What is resilience?
Explore: Natural Hazards Assessment

Less than one percent of algal blooms actually produce toxins. Harmful algal blooms are blooms of species of algae that can have negative impacts on humans, marine and freshwater environments, and coastal economies. These blooms occur when phytoplankton, which are tiny microscopic plants, grow quickly in large quantities while producing toxic or harmful effects on people, fish, shellfish, marine mammals, and birds.

A bloom does not have to produce toxins in order to be harmful to the environment. It can also be harmful by causing anoxic conditions where oxygen is depleted from the water. Blooms can block light to organisms lower in the water column, or even clog or harm fish gills.

Not all algal blooms are harmful, some can actually be beneficial. Phytoplankton are found at the base of the marine food chain therefore all other life in the ocean relies on phytoplankton. Blooms can also be a good indicator of environmental change not only in the water, but also on land.

For more information:
National Centers for Coastal Ocean Science
Diving Deeper Podcast, Episode 17 (Oct. 7, 2009) - What is a harmful algal bloom?

With the advent of online mapping tools such as Google Earth, exploring our planet is easier than ever before. Recently, many of these tools have been updated to provide detailed seafloor mapping data, or bathymetry.

With legions of people around the world now exploring the seafloor, many are noticing locations along the ocean bottom marked by mysterious formations of grid-like artifacts. These formations look like they were made by humans, leading many to ask if these areas could be lost cities or underwater streets.

While these formations are human-made, they are only made of data. In other words, there are no physical lines on the ocean floor. These lines are artifacts of the ocean floor mapping process.

Oceanographers use sonar—sound waves—to map the ocean bottom. These sonar readings are typically taken by ships towing submersible devices that send out sound waves. The sound travels through the ocean, bounces off the seafloor, then travels back to the ships. This process creates a sound 'image' of the peaks and valleys on the ocean bottom.

NOAA is just one of many agencies around the world that uses sonar to 'see' what the seafloor looks like. Some of these surveys of the ocean bottom cover small areas in great detail. Other surveys are broad-brushed, showing vast areas at low resolutions.

Online mapping tools take these many different sonar surveys created by a variety of agencies and organizations, stitch them together, and pile them up on top of each other in layers. Taken together, these sonar maps provide a seamless picture of what the ocean bottom looks like around the globe. However, some areas appear in more detail than others.

When you see strange grid-like formations on the seafloor while using an online mapping tool, what you are really seeing is two (or more) different maps layered on top of each other. One map may show a large, low-resolution picture of the ocean floor. This map will show little detail and will look smooth. The other map, or 'data set,' often looks like a bunch of grid-like lines overlaying the smooth, low-detail map. The path of the lines show the paths traveled by the ships that gathered these higher-resolution sonar readings of smaller patches of the ocean.

For more information:
What is sonar?, Ocean Facts
Surveys and Wrecks, Office of Coast Survey
Understanding Ocean Acoustics, NOAA Ocean Explorer
Sonar, NOAA Ocean Explorer

Scientists measure the times, heights, and extents of both the inflow and outflow of the tidal waters that support a number of different aspects of our daily lives. Navigating ships safely through shallow water ports, intracoastal waterways, and estuaries requires knowledge of the time and height of the tides as well as the speed and direction of the tidal currents. Mariners need accurate data because the depths and widths of the channels and increased marine traffic leaves very little room for error.

Engineers need data to monitor fluctuating tide levels for harbor engineering projects such as the construction of bridges and docks. Projects involving the construction, demolition, or movement of large structures must be scheduled far in advance if an area experiences wide fluctuations in water levels during its tidal cycle. Habitat restoration projects also require accurate knowledge of tide and current conditions.

Tidal data is also critical to fishing, recreational boating, and surfing. Commercial and recreational fishermen use their knowledge of the tides and tidal currents to help them improve their catches. Depending on the species and water depth in a particular area, fish may concentrate during ebb or flood tidal currents.

For more information:
Center for Operational Oceanographic Products and Services
NOS Education Tutorial: Tides
Diving Deeper Podcast, Episode 6 (Apr. 8, 2009) - What are tides?

Many organizations use geodesy to map the U.S. shoreline, determine land boundaries, and improve transportation and navigation safety. To measure points on the Earth’s surface, geodesists assign coordinates (similar to a unique address) to points all over the Earth. In the past, geodesists determined the coordinates of points by using Earth-based surveying tools to measure the distances between points. Today, geodesists use space-based tools like the Global Positioning System (GPS) to measure points on the Earth’s surface.

Geodesists must accurately define the coordinates of points on the surface of the Earth in a consistent manner. A set of accurately measured points is the basis for the National Spatial Reference System, which allows different kinds of maps to be consistent with one another.

For more information:
National Geodetic Survey
National Spatial Reference System
Diving Deeper Podcast, Episode 9 (May 20, 2009) - What is geodesy?
Geodesy Tutorial, NOS Education

These chemicals were banned in the U.S. in 1979 amid suggestions that PCBs could have unintended impacts on human and environmental health. From the 1920s until their ban, an estimated 1.5 billion pounds of PCBs were made for things such as microscope oils, electrical insulators, capacitors, and electric appliances such as television sets or refrigerators. PCBs were also sprayed on dirt roads to keep the dust down prior to knowing some of the unintended consequences from widespread use. 

Prior to the ban in 1979, PCBs entered the air, water, and soil during manufacture and use. Wastes from the manufacturing process that contained PCBs were often placed in dump sites or landfills. Occasionally, accidental spills and leaks from these facilities or transformer fires could result in PCBs entering the environment.

PCBs can be found worldwide. In the 1960s, when initial research results were released, traces of PCBs could be detected in people and animals around the world – not only in heavily populated areas such as New York City, but also in remote areas as far as the Arctic. These findings of such widespread and persistent contamination contributed to the banning of the chemical in 1979.

PCBs can degrade or breakdown in the environment, but the process greatly depends on the chemical makeup of the PCBs. The degrading process also depends on where the PCBs are in the environment. Typically, PCBs are either broken down in the environment by sunlight or by microorganisms. Sunlight plays an important role in the breakdown of PCBs when they are in the air, shallow water, or surface soils. Microorganisms, such as bacteria, algae, or fungi, biodegrade PCBs when found in soil or sediments.

For more information:
Office of Response and Restoration
Diving Deeper Podcast, Episode 11 (June 17, 2009) - What are PCBs?

Land cover data documents how much of a region is covered by forests, wetlands, impervious surfaces, agriculture, and other land and water types. Water types include wetlands or open water. Land use shows how people use the landscape – whether for development, conservation, or mixed uses. The different types of land cover can be managed or used quite differently.

Land cover can be determined by analyzing satellite and aerial imagery. Land use cannot be determined from satellite imagery. Land cover maps provide information to help managers best understand the current landscape. To see change over time, land cover maps for several different years are needed. With this information, managers can evaluate past management decisions as well as gain insight into the possible effects of their current decisions before they are implemented.

Coastal managers use land cover data and maps to better understand the impacts of natural phenomena and human use of the landscape. Maps can help managers assess urban growth, model water quality issues, predict and assess impacts from floods and storm surges, track wetland losses and potential impacts from sea level rise, prioritize areas for conservation efforts, and compare land cover changes with effects in the environment or to connections in socioeconomic changes such as increasing population.

For more information:
NOAA Coastal Services Center
Diving Deeper Podcast, Episode 14 (July 29, 2009) - What is land cover data?

This process is also known as eutrophication. Excessive amounts of nutrients can lead to more serious problems such as low levels of oxygen dissolved in the water. Severe algal growth blocks light that is needed for plants, such as seagrasses, to grow. When the algae and seagrass die, they decay. In the process of decay, the oxygen in the water is used up and this leads to low levels of dissolved oxygen in the water. This, in turn, can kill fish, crabs, oysters, and other aquatic animals.

Nutrients come from a variety of different sources. They can occur naturally as a result of weathering of rocks and soil in the watershed and they can also come from the ocean due to mixing of water currents. Scientists are most interested in the nutrients that are related to people living in the coastal zone because human-related inputs are much greater than natural inputs. Because there are increasingly more people living in coastal areas, there are more nutrients entering our coastal waters from wastewater treatment facilities, runoff from land in urban areas during rains, and from farming.

All of these factors can lead to increased nutrient pollution.

For more information:
National Centers for Coastal Ocean Science
Diving Deeper Podcast, Episode 1 (Jan. 26, 2009) - What is eutrophication?
Nonpoint Source Pollution Tutorial, NOS Education

A community that is more informed and prepared will have a greater opportunity to rebound quickly from weather and climate-related events, including adapting to sea level rise. The ability to rebound more quickly can reduce negative human health, environmental, and economic impacts.

The ability of a community to successfully recover is linked to the strengths and capacities of individuals, families, businesses, schools, hospitals, and other parts of the community. Also, there are more people moving into high-risk areas such as the coast. With these population increases, homes, businesses, and infrastructure are also at great risk of damage from hazards. 

Because all communities are going to face hazards, resilience is important. Resilience is our ability to prevent a short-term hazard event from turning into a long-term community-wide disaster. While most communities effectively prepare themselves to respond to emergency situations, many are not adequately prepared to recover in the aftermath.

For more information:
NOAA Coastal Services Center
NOAA's Office of Ocean and Coastal Resource Management
Diving Deeper Podcast, Episode 10 (June 3, 2009) - What is resilience?
Explore: Natural Hazards Assessment

An environmental sensitivity index (ESI) map compiles information for coastal shoreline sensitivity, biological resources, and human resources. This information is used to create cleanup strategies before an accident occurs so that authorities are prepared to take action in the event of such a spill. Advance planning reduces the harmful consequences of oil spills and cleanup.

ESI maps have many features that make them great tools for spill response teams. The maps use geographic information system techniques in order to combine regional maps with data on biological and human resources in an area, as well as information on sensitive shorelines. The resources are given ranks and color coded based on their sensitivity to oiling. Organizations can use the synthesized data to create efficient and effective cleanup strategies.

Researchers in the Office of Response and Restoration work with state, federal, and industrial agencies to create ESI maps.

For more information:
Environmental Sensitivity Maps, Office of Response and Restoration
Environmental Sensitivity Index Mapping (pdf, 1.6Mb)

Less oxygen dissolved in the water is often referred to as a “dead zone” because most marine life either dies, or, if they are mobile such as fish, leave the area. Habitats that would normally be teeming with life become, essentially, biological deserts.

Hypoxic zones can occur naturally, but scientists are concerned about the areas created or enhanced by human activity. There are many physical, chemical, and biological factors that combine to create dead zones, but nutrient pollution is the primary cause of those zones created by humans. Excess nutrients that run off land or are piped as wastewater into rivers and coasts can stimulate an overgrowth of algae, which then sinks and decomposes in the water. The decomposition process consumes oxygen and depletes the supply available to healthy marine life.

Dead zones occur in many areas of the country, particularly along the East Coast, the Gulf of Mexico, and the Great Lakes, but there is no part of the country or the world that is immune. The second largest dead zone in the world is located in the U.S., in the northern Gulf of Mexico.

For more information:
National Centers for Coastal Ocean Science
Diving Deeper Podcast, Episode 12 (Jul. 1, 2009) - What is a dead zone?
Hypoxia and Nutrient Pollution Overview
Hypoxia in the Northern Gulf of Mexico

Within their protected waters, giant humpback whales breed and calve their young, temperate reefs flourish, and shipwrecks tell stories of our maritime history. Similar to national parks on the land, these underwater preserves provide a safe habitat for species close to extinction or protect historically significant shipwrecks.

Ranging in size from less than 2.6 square kilometers to 356,880 square kilometers (one square mile to 137,792 square miles), each sanctuary site is a unique place needing special protections. Marine sanctuaries are natural classrooms, cherished recreational spots, and valuable commercial industries.

Our national marine sanctuaries are part of a larger network called the National Marine Sanctuary System. The Sanctuary System consists of 14 marine protected areas that encompass more than 388,498 square kilometers (150,000 square miles) of marine and Great Lakes waters from Washington State to the Florida Keys, and from Lake Huron to American Samoa. The system includes 13 national marine sanctuaries and the Northwestern Hawaiian Islands Marine National Monument.

For more information:
Office of National Marine Sanctuaries
Diving Deeper Podcast, Episode 8 (May 6, 2009) - What is a national marine sanctuary?

Here are some things YOU can do:

• Educate yourself about why healthy coral reefs are valuable to the people, fish, plants, and animals that depend on them.
• Become an informed consumer and learn how your daily choices like water use, recycling, seafood, vacation spots, fertilizer use, and driving times can positively (or negatively) impact the health of coral reefs.
• Find out about existing and proposed laws, programs, and projects that could affect the nation’s coral reefs (or reefs in your area, if this applies to you).
• Remember to vote at the polls and with your dollars.
• Dive into action by volunteering for a fish count or a beach or reef cleanup.

There are also many things you can do to ensure that you are environmentally conscious when you visit coral reefs or coastal areas. These include things such as hiring local guides to support the local economy, choosing to buy souvenirs that are not made from reef organisms, removing all trash from an area, and never touching or harassing wildlife in reef areas.

Finally, stay informed and spread the word! Your excitement will help get others involved.

For more information:
NOAA Coral Reef Conservation Program
What are Corals?
Things You Can Do to Protect Coral Reefs
Coral Tutorial, NOS Education
Explore: Coral Reef Conservation

Remote sensors collect data by detecting the energy that is reflected from Earth. These sensors can be on satellites or mounted on aircraft.

Remote sensors can be either passive or active. Passive sensors respond to external stimuli. They record radiation that is reflected from Earth’s surface, usually from the sun. Because of this, passive sensors can only be used to collect data during daylight hours.

In contrast, active sensors use internal stimuli to collect data about Earth. For example, a laser-beam remote sensing system projects a laser onto the surface of Earth and measures the time that it takes for the laser to reflect back to its sensor.

Remote sensing has a wide range of applications in many different fields:

• Coastal applications: Monitor shoreline changes, track sediment transport, and map coastal features. Data can be used for coastal mapping and erosion prevention.
• Ocean applications: Monitor ocean circulation and current systems, measure ocean temperature and wave heights, and track sea ice. Data can be used to better understand the oceans and how to best manage ocean resources.
• Hazard assessment: Track hurricanes, earthquakes, erosion, and flooding. Data can be used to assess the impacts of a natural disaster and create preparedness strategies to be used before and after a hazardous event.
• Natural resource management: Monitor land use, map wetlands, and chart wildlife habitats. Data can be used to minimize the damage that urban growth has on the environment and help decide how to best protect natural resources.

For more information:
Remote Sensing Division, National Geodetic Survey
Coastal Remote Sensing Program, NOAA Coastal Services Center
Remote Sensing: An Overview

An ecosystem is an ecological community comprised of biological, physical, and chemical components, considered as a unit.

NOS scientists monitor, research, and study ecosystem science on many levels. They may monitor entire ecosystems or they may study the chemistry of a single microbe. This wide range of data is collected into combined assessments that describe current ecosystem health, predict the future state of an ecosystem, and evaluate different management strategies that may improve the health of an ecosystem.

NOS focuses its efforts on ecosystems that are given importance by legislative and executive orders. These areas include coral reefs, estuaries, national marine sanctuaries, national estuarine research reserves, and other ocean ecosystems. The areas are observed and studied to determine how they are affected by human actions. Strategies are then formed in order to best protect these valuable ecosystems in order to keep them safe and healthy.

For more information:

Coastal Ecosystem Science

National Centers for Coastal Ocean Science

Turbidity is a measure of the level of particles such as sediment, plankton, or organic by-products, in a body of water. As the turbidity of water increases, it becomes denser and less clear due to a higher concentration of these light-blocking particles.

Turbidity currents can be set into motion when mud and sand on the continental shelf are loosened by earthquakes, collapsing slopes, and other geological disturbances. The turbid water then rushes downward like an avalanche, picking up sediment and increasing in speed as it flows.

Turbidity currents can change the physical shape of the sea floor by eroding large areas and creating underwater canyons. These currents also deposit huge amounts of sediment wherever they flow, usually in a gradient or fan pattern, with the largest particles at the bottom and the smallest ones on top.

NOAA scientists use current meters attached with turbidity sensors to gather data near underwater volcanoes and other highly active geological sites. Also, satellite imagery is used to observe turbidity by measuring the amount of light that is reflected by a section of water.

For more information:
Ocean Geologic Features (pdf, 2Mb), NOAA Ocean Explorer
Ocean Turbidity, NOAA Coastal Services Center

A lunar day is how long it takes for one point on the Earth to make one complete rotation and end up at the same point in relation to the moon. The reason that a lunar day is longer than a normal 24-hour day is because the moon rotates around the Earth in the same direction that the Earth is spinning. It takes the Earth an extra 50 minutes to “catch up” to the moon.

Tides are very long waves that move across the oceans. They are caused by the gravitational forces exerted on the earth by the moon, and to a lesser extent, the sun. When the highest point in the wave, or the crest, reaches a coast, the coast experiences a high tide. When the lowest point, or the trough, reaches a coast, the coast experiences a low tide.

Imagine the ocean is shaped like a football pointing at the moon. The football’s pointed ends represent the parts of the Earth experiencing high tide and the football’s flat sides are the parts of the earth experiencing low tide.

The point facing the moon is formed because the gravitational pull of the moon is strongest on whichever side of the Earth faces it. Gravity pulls the ocean towards the moon and high tide occurs.

The bulge on the far side of the Earth is caused by inertia. The water moving away from the moon resists the gravitational forces that attempt to pull it in the opposite direction. Because the gravitational pull of the moon is weaker on the far side of the Earth, inertia wins, the ocean bulges out and high tide occurs.

As the Earth spins, different areas of the planet face the moon, and this rotation causes the tides to cycle around the planet.

NOS scientists advanced tidal recording systems as well as satellite imagery to monitor tides and water levels. These data are used to predict ocean behavior in order to protect our coasts and coastal communities.

For more information:
Center for Operational Oceanographic Products and Services
Tides Tutorial, NOS Education
What are Tides? - Diving Deeper audio podcast

Phytoplankton, also known as microalgae, are similar to terrestrial plants in that they contain chlorophyll and require sunlight in order to live and grow. Most phytoplankton are buoyant and float in the upper part of the ocean, where sunlight penetrates the water. Phytoplankton also require inorganic nutrients such as nitrates, phosphates, and sulfur which they convert into proteins, fats, and carbohydrates.

The two main classes of phytoplankton are dinoflagellates and diatoms. Dinoflagellates use a whip-like tail, or flagella, to move through the water and their bodies are covered with complex shells. Diatoms also have shells, but they are made of a different substance and their structure is rigid and made of interlocking parts. Diatoms do not rely on flagella to move through the water and instead rely on ocean currents to travel through the water.

In a balanced ecosystem, phytoplankton provide food for a wide range of sea creatures including whales, shrimp, snails, and jellyfish. When too many nutrients are available, phytoplankton may grow out of control and form harmful algal blooms (HABs). These blooms can produce extremely toxic compounds that have harmful effects on fish, shellfish, mammals, birds, and even people.

The National Centers for Coastal Ocean Science conduct extensive research on harmful algal blooms. Scientists use a range of technologies to predict where and when HABs are likely to form and how they will affect the areas where they occur. Scientists use this information to inform coastal authorities on how to best respond in order to minimize negative impacts.

For more information:
NOAA's National Centers for Coastal Ocean Science
Phytoplankton -- What Are They?, Northwest Fisheries Science Center
Phytoplankton Monitoring Network
Harmful Algal Blooms

Seamounts are formed by volcanic activity and can be taller than 3,000 meters (10,000 feet).  They can be isolated or part of large mountain chains. The New England Seamount contains more than 30 peaks that stretch 1,600 kilometers (994 miles) from the coast of New England.

Seamounts often have a high level of biological productivity because they provide habitats for many species of plants and animals. Over 200 species of sea creatures have been observed at a single guyot in the New England Seamount. Seamounts are great locations to discover new species because each seamount houses different types of animals, including many that can only be found in guyot habitats.

Seamounts are home to many commercial fish and are therefore very beneficial to our economy. Seamounts are also important to the field of medicine, as any number of undiscovered species may lead to new drugs or medical treatments.

For more information:
Mountains in the Sea Exploration: No Escape (pdf, 1.2Mb), NOAA Ocean Explorer
Davidson Seamount, Office of National Marine Sanctuaries

Although first observed in 1513 by Ponce de Leon, the Gulf Stream was not charted until the early 1770s by Benjamin Franklin, with the help of a Nantucket sea captain.

Around 1770, the Board of Customs in Boston, Massachusetts, noticed that packets travelling between Falmouth, Massachusetts, and New York, New York, by sea took two weeks longer to arrive than merchants travelling from London to Rhode Island. This was perplexing as Falmouth and New York were less than a day apart by road.

Franklin spoke with a sea captain who told him that while fishing for whales, he noticed that the whales would swim alongside the Gulf Stream, but never in it. Fishermen would frequently cross the Gulf Stream, where they passed packet ships sailing within, against the current. This was the reason for the delays. Franklin had the captain mark the location of the Gulf Stream, as well as the directions of its currents.

In 1843, the United States Coast Survey, NOAA’s earliest “ancestor”, set out to study the Gulf Stream in more detail. They wanted to determine the depth of the water, the temperature of the water at different depths, the characteristics of the ocean bottom, the direction and velocity of the currents at different depths, and the extent of plant and animal life. Their early observations led them to discover features such as cool and warm water banding, as well as the “Charleston Bump.”

For more information:
History of Ocean Exploration: Early Years (1807-1865), NOAA Ocean Explorer
1785: Benjamin Franklin's 'Sundry Maritime Observations', NOAA Ocean Explorer

Algin, an emulsifying and bonding agent, is extracted from kelp and used in these products. Kelp is also used as food on mollusk farms. Between 100,000 and 170,000 wet tons of kelp are harvested from California waters each year.

Kelp forests are extremely biologically productive habitats for a huge range of sea creatures including fish, urchins, sea otters, sea lions, and even some whales. Because of this, kelp forests are critical for fishing and recreation industries.

Sadly, overfishing disrupts the balance of kelp forests by removing predators and allowing plant-eating populations to explode and overeat the kelp, destroying the forests. Pollution, such as sediment runoff and industrial waste, also contributes to the destruction of kelp forests.

Today, many kelp forests are located in marine protected areas and are studied by NOAA scientists. Kelp forests are monitored for kelp size and distribution, physical oceanic conditions, and associated life. The more that we discover about these amazing habitats, the better they can be preserved and strengthened.

For more information:
Ecosystems: Impacts on Kelp Forests, National Marine Sanctuaries
Kelp Forests, Olympic Coast National Marine Sanctuary
Kelp Forest and Rocky Subtidal Habitats, Monterey Bay National Marine Sanctuary

Whale sharks can grow to 15 meters (50 feet) and weigh as much as 40 tons by some estimates! They have broad, flat heads with short snouts and their backs have an interesting white, yellow, and grey checkerboard pattern. Whale sharks can live up to 100 years.

These fish inhabit waters off the coast of New York to central Brazil and they prefer water temperatures of 20-25°C (68-77°F).

Whale sharks eat mostly organisms floating in the water that they strain from the water through their meter-long mouths as they swim.

In 2003, a group of scientists, including a NOAA staff member, met at Ningaloo Reef in Western Australia to study and track the diving and migration patterns of the whale shark. Their data showed that the sharks generally swim at depths of 50-60 meters (164-197 feet) during the day, perhaps using the sunlight to aid in the search for food. At night, the sharks swim closer to the surface.

For more information:
Whale Shark, NOAA Fisheries, Northeast Fisheries Science Center, Narragansett Laboratory

Studying Pelagics, Ocean Explorer

Only about a dozen of the more than 300 species of sharks have been involved in attacks on humans. Sharks evolved millions of years before humans existed and therefore humans are not part of their normal diets. Sharks primarily feed on smaller fish but some species prey upon seals, sea lions, and other marine mammals.

Sharks have been known to attack humans when they are confused or curious. If a shark sees a human splashing in the water, it may try to investigate, leading to an accidental attack. Still, sharks have more to fear from humans than we do of them. Humans hunt sharks for their meat, internal organs, and skin in order to make products such as shark fin soup, lubricants, and leather.

Sharks are a valuable part of marine ecosystems, but overfishing threatens some shark populations. NOAA Fisheries conducts research on shark habitats, migratory patterns, and population change in order to understand how to best protect and maintain a stable shark population.

For more information:
General Shark Information, NOAA Fisheries
Sharks, Gray's Reef National Marine Sanctuary
Shark Food Habits Studies, NOAA Fisheries Service's Southwest Fisheries Science Center

Smart growth is a way of approaching community development and expansion with the goal of making them “more livable, more economically efficient, and more effective at meeting the needs of the people who live there.”

Smart growth encourages building communities that are easily walkable while also providing a range of other transportation options. Houses are built to be attractive and affordable using compact, energy efficient designs. These tenets, as well as an overall goal of environmental respect and preservation guide smart growth community building.

The NOAA Coastal Services Center has created recommendations for how these principles can be applied to an actual coastal community. These recommendations include a Conventional Design that aims to maximize lot development and deemphasizes environmental preservation. The Conservation Design focuses on preservation of natural resources and open space and works to meet and exceed required environmental protection standards. Lastly, the New Urbanist Design surrounds a central open space with a network of interconntected commercial and residential areas.

For more information:
Alternatives for Coastal Development: One Site, Three Scenarios, NOAA Coastal Services Center
Coastal Decision-making Lesson Plan(pdf, 200kb), NOS Education
Coastal Decision-making Tools

Covering approximately 155 million square kilometers (59 million square miles) and containing more than half of the free water on Earth, the Pacific is by far the largest of the world’s ocean basins. All of the world’s continents could fit into the Pacific basin.

The Pacific is the oldest of the existing ocean basins. Its oldest rocks have been dated at about 200 million years. The Pacific basin is referred to as the “Ring of Fire” due to intense earthquake and volcanic activity occurring near areas of tectonic plate subduction (where one tectonic plate is forced under another).

The Atlantic basin is the second largest basin, followed by the Indian Ocean basin, the Southern Ocean, and finally the Arctic Ocean basin.

For more information:
New Zealand American Submarine Ring of Fire 2007, NOAA Ocean Explorer
Submarine Ring of Fire 2006, NOAA Ocean Explorer

Seawater contains salt. When humans drink seawater, their cells are thus taking in water and salt. While humans can safely ingest small amounts of salt, the salt content in seawater is much higher than what can be processed by the human body. Additionally, when we consume salt as part of our daily diets, we also drink liquids, which help to dilute the salt and keep it at a healthy level. Living cells do depend on sodium chloride (salt) to maintain the body’s chemical balances and reactions; however, too much sodium can be deadly.

Human kidneys can only make urine that is less salty than salt water. Therefore, to get rid of all the excess salt taken in by drinking seawater, you have to urinate more water than you drank. Eventually, you die of dehydration even as you become thirstier.

For more information:
Why is the ocean salty?

There are over 1,700 marine protected areas, or MPAs, in the U.S. that cover approximately 34 percent of marine waters. MPAs are found in every region of the United States. The West Coast (California, Oregon, and Washington) has the highest number of MPAs; however, the region with the largest area of MPAs is the Pacific Islands. This is because of the designation of the Papahānaumokuākea Marine National Monument, which is one of the largest marine conservation areas in the world.  

MPAs are not strictly located in deep or coastal marine waters. There are six federal MPAs and more than 30 state-managed MPAs located within the Great Lakes. Most of the Great Lakes MPAs were created to protect cultural resources, like shipwrecks and historical artifacts. One example of a Great Lakes MPA is the Thunder Bay National Marine Sanctuary. This MPA was created to protect the more than 160 shipwrecks it contains.

The National MPA Center has inventoried all of the existing U.S. MPAs and found that almost 70 percent of these areas are managed by coastal states and territories, while fewer than 30 percent are under federal jurisdiction. Many state MPAs were created to protect specific coastal habitats and resources, like beaches and nesting bird habitats. Most of the federally managed MPAs include sites like the national marine sanctuaries, national parks, seashores and wildlife refuges, and federal fishery closures.

For more information:

Marine Protected Areas Center
Office of National Marine Sanctuaries
Office of Ocean and Coastal Resource Management
Diving Deeper Podcast, Episode 2 (Feb. 9, 2009) - What Is a Marine Protected Area?

IOOS coastal and marine data (e.g., water temperature, water level, currents, winds, and waves) are collected by many different tools including satellites, buoys, tide gauges, radar stations, and underwater vehicles. A variety of tools is needed to collect data on global, national, regional, and local levels. Some of these tools are in the water collecting data while others may be on land or in space. Most of the data collected are streamed to a database, making them easier to access.

While many of these data collection tools already exist, the benefit of IOOS is the one common system to connect all of these data so that scientists can quickly find information to track, predict, manage, and adapt to changes in our marine environment.

For more information:
NOAA Integrated Ocean Observing System Program
Diving Deeper Podcast, Episode 2 (Mar. 9, 2009) - What is IOOS?

El Niño and La Niña are opposite phases of what is known as the El Niño-Southern Oscillation (ENSO) cycle. The ENSO cycle is a scientific term that describes the fluctuations in temperature between the ocean and atmosphere in the (approximately between the International Date Line and 120 degrees West).

La Niña is sometimes referred to as the cold phase of ENSO and El Niño as the warm phase of ENSO. These deviations from normal surface temperatures can have large-scale impacts not only on ocean processes, but also on global weather and climate.

El Niño and La Niña episodes typically last nine to 12 months, but some prolonged events may last for years. They often begin to form between June and August, reach peak strength between December and April, and then decay between May and July of the following year. While their periodicity can be quite irregular, El Niño and La Niña events occur about every three to five years. Typically, El Niño occurs more frequently than La Niña.

El Niño

El Niño means The Little Boy, or Christ Child in Spanish. El Niño was originally recognized by fishermen off the coast of South America in the 1600s, with the appearance of unusually warm water in the Pacific Ocean. The name was chosen based on the time of year (around December) during which these warm waters events tended to occur.

The term El Niño refers to the large-scale ocean-atmosphere climate interaction linked to a periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific.

Typical El Niño effects are likely to develop over North America during the upcoming winter season. Those include warmer-than-average temperatures over western and central Canada, and over the western and northern United States. Wetter-than-average conditions are likely over portions of the U.S. Gulf Coast and Florida, while drier-than-average conditions can be expected in the Ohio Valley and the Pacific Northwest.

La Niña

La Niña means The Little Girl in Spanish. La Niña is also sometimes called El Viejo, anti-El Niño, or simply "a cold event."

La Niña episodes represent periods of below-average sea surface temperatures across the east-central Equatorial Pacific. Global climate La Niña impacts tend to be opposite those of El Niño impacts. In the tropics, ocean temperature variations in La Niña also tend to be opposite those of El Niño.

During a La Niña year, winter temperatures are warmer than normal in the Southeast and cooler than normal in the Northwest.

For more information:
NOAA El Niño Page
NOAA La Niña Page
NOAA National Weather Service Climate Prediction Center, El Niño/La Niña
NOAA Pacific Marine Environmental Laboratory: El Niño theme page

Kelp forests can be seen along much of the west coast of North America. Kelp are large brown algae that live in cool, relatively shallow waters close to the shore. They grow in dense groupings much like a forest on land. These underwater towers of kelp provide food and shelter for thousands of fish, invertebrates, and marine mammal species.

Kelp forests harbor a greater variety and higher diversity of plants and animals than almost any other ocean community. Many organisms use the thick blades as a safe shelter for their young from predators or even rough storms.

Among the many mammals and birds that use kelp forests for protection or feeding include seals, sea lions, whales, sea otters, gulls, terns, snowy egrets, great blue herons, cormorants, and shore birds.

These dense canopies of algae generally occur in cold, nutrient-rich waters. Because of their dependency upon light for photosynthesis, kelp forests form in shallow open waters and are rarely found deeper than 15-40 meters (49-131 feet).

NOAA scientists study kelp forests by visiting the same locations over and over to assess the presence and abundance of a variety of organisms. Monitoring allows marine scientists to determine if the kelp forest is changing over time and to identify the cause of those changes, whether natural or human.

For more information:

Kelp Forests, National Marine Sanctuaries

Kelp Forest and Rocky Subtidal Habitats, Monterey Bay National Marine Sanctuary

The great ocean conveyor moves water around the globe.

The ocean is not a still body of water. There is constant motion in the ocean in the form of a global ocean conveyor belt. This motion is due to thermohaline currents (thermo = temperature; haline = salinity). Cold, salty water is dense and sinks to the bottom of the ocean while warm water is less dense and rises to the surface.

The ocean conveyor gets it “start” in the Norwegian Sea, where warm water from the Gulf Stream heats the atmosphere in the cold northern latitudes. This loss of heat to the atmosphere makes the water cooler and denser, causing it to sink to the bottom of the ocean. As more warm water is transported north, the cooler water sinks and moves south to make room for the incoming warm water. This cold bottom water flows south of the equator all the way down to Antarctica. Eventually, the cold bottom waters are able to warm and rise to the surface, continuing the conveyor belt that encircles the globe.

It takes almost 1,000 years for the conveyor belt to complete one “cycle.”

For more information:
The Global Conveyor Belt, NOS Education
Ocean Conveyor Belt, NOAA Science on A Sphere

Stony corals (or scleractinians) are the corals primarily responsible for laying the foundations of, and building up, reef structures. Massive reef structures are formed when each individual stony coral organism – or polyp – secretes a skeleton of calcium carbonate.

Most stony corals have very small polyps, averaging one to three millimeters (0.04 to 0.12 inches) in diameter, but entire colonies can grow very large and weigh several tons. These colonies consist of millions of polyps that grow on top of the limestone remains of former colonies, eventually forming massive reefs.

In general, massive corals tend to grow slowly, increasing in size from 0.5 to two centimeters (0.2 to 0.8 inches) per year. However, under favorable conditions (lots of light, consistent temperature, moderate wave action), some species can grow as much as 4.5 centimeters (1.8 inches) per year.

For more information:
What are Corals and Coral Reefs? – NOAA Coral Reef Information System
Corals – NOS Education
Coral Reef Conservation
NOAA's Coral Reef Conservation Program

Many people are interested in climate change and how a changing climate will affect the ocean. With the majority of Americans living in coastal states, rising water levels can have potentially large impacts. Scientists have determined that global sea level has been steadily rising since 1900 at a rate of at least 1 to 2.5 millimeters (0.04 to 0.1 inches) per year.

Sea level can rise by two different mechanisms with respect to climate change. First, as the oceans warm due to an increasing global temperature, seawater expands—taking up more space in the ocean basin and causing a rise in water level. The second mechanism is the melting of ice over land, which then adds water to the ocean. The Intergovernmental Panel on Climate Change predicts that total global-average sea level rise from 1990 - 2100 will be 110 to 770 millimeters (4.3 to 30.3 inches).

For more information:
Sea Levels Online, Center for Operational Oceanographic Products and Services
Sea Level Rise, NOAA Science On a Sphere

There are about 80 different species of mangrove trees. All of these trees grow in areas with low-oxygen soil, where slow-moving waters allow fine sediments to accumulate. Mangrove forests only grow at tropical and subtropical latitudes near the equator because they cannot withstand freezing temperatures.

Many mangrove forests can be recognized by their dense tangle of prop roots that make the trees appear to be standing on stilts above the water. This tangle of roots allows the trees to handle the daily rise and fall of tides, which means that most mangroves get flooded at least twice per day.  The roots also slow the movement of tidal waters, causing sediments to settle out of the water and build up the muddy bottom.

Mangrove forests stabilize the coastline, reducing erosion from storm surges, currents, waves, and tides. The intricate root system of mangroves also makes these forests attractive to fishes and other organisms seeking food and shelter from predators.

For more information:
Mangrove Forests, NOS Education
Habitat Types: Mangrove Forests, NOAA Fisheries

Estuaries are tidally driven. Tides flush the system and provide nutrients to keep food webs functional. By doing this, tides create constantly changing conditions of exposure to air or increased levels of water in an estuarine environment. Because of tides, the water levels in an estuary are going up and down several times a day.

Estuarine organisms can adapt quite well to these changing conditions in estuaries. For example, fish or crabs are mobile and can move as needed throughout the day to adjust to changes in the estuary.

In addition, weather patterns, seasonal cycles, and climate change also affect and can change conditions in estuaries.

Estuaries and their surrounding wetlands are bodies of water usually found where rivers meet the sea. Estuaries are home to unique plant and animal communities that have adapted to brackish water.

For more information:
Estuaries.gov - About Estuaries
Estuaries (Diving Deeper podcast, 4.22.09)
National Estuarine Research Reserve System
Estuaries, NOS Education

Estuaries - areas where fresh and saltwater mix - are made up of many different types of habitats. These habitats can include oyster reefs, coral reefs, rocky shores, submerged aquatic vegetation, marshes, and mangroves. There are also different animals that live in each of these different habitats. Fish, shellfish, and migratory birds are just a few of the animals that can live in an estuary.

For example, there are several habitats that make up the Chesapeake Bay. There are oyster reefs where oysters, mud crabs, and small fish may be found. Also in the Chesapeake Bay, there is submerged aquatic vegetation where seahorses, blue crabs, and other fish live. Finally, there is open water where sea turtles or rays can be found.

For more information:
Esturaries.gov - Life in an Estuary
Diving Deeper, Episode (Apr. 22, 2009) – What is an estuary?
National Estuarine Research Reserve System
Estuaries, NOS Education

Oceanography covers a wide range of topics, including marine life and ecosystems, ocean circulation, plate tectonics and the geology of the sea floor, and the chemical and physical properties of the ocean.

Just as there are many specialties within the medical field, there are many disciplines within oceanography.

Biological oceanographers and marine biologists study plants and animals in the marine environment. They are interested in the numbers of marine organisms and how these organisms develop, relate to one another, adapt to their environment, and interact with it. To accomplish their work, they may use field observations, computer models, or laboratory and field experiments.

Chemical oceanographers and marine chemists study the composition of seawater, its processes and cycles, and the chemical interaction of seawater with the atmosphere and sea floor. Their work may include analysis of seawater components, the effects of pollutants, and the impacts of chemical processes on marine organisms. They may also use chemistry to understand how ocean currents move seawater around the globe and how the ocean affects climate or to identify potentially beneficial ocean resources such as natural products that can be used as medicines.

Geological oceanographers and marine geologists explore the ocean floor and the processes that form its mountains, canyons, and valleys. Through sampling, they look at millions of years of history of sea-floor spreading, plate tectonics, and oceanic circulation and climates. They also examine volcanic processes, mantle circulation, hydrothermal circulation, magma genesis, and crustal formation. The results of their work help us understand the processes that created the ocean basins and the interactions between the ocean and the sea floor.

Physical oceanographers study the physical conditions and physical processes within the ocean such as waves, currents, eddies, gyres and tides; the transport of sand on and off beaches; coastal erosion; and the interactions of the atmosphere and the ocean. They examine deep currents, the ocean-atmosphere relationship that influences weather and climate, the transmission of light and sound through water, and the ocean's interactions with its boundaries at the sea floor and the coast.

All of these fields are intertwined, and thus all oceanographers must have a keen understanding of biology, chemistry, geology, and physics to unravel the mysteries of the world ocean and to understand processes within it.

For more information:
NOAA Ocean Explorer: OceanAGE Careers
MarineCareers.net

Rip currents are powerful, narrow channels of fast-moving water that are prevalent along the East, Gulf, and West coasts of the U.S., as well as along the shores of the Great Lakes.

Moving at speeds of up to eight feet per second, rip currents can move faster than an Olympic swimmer.

Panicked swimmers often try to counter a rip current by swimming straight back to shore—putting themselves at risk of drowning because of fatigue.

Lifeguards rescue tens of thousands of people from rip currents in the U.S. every year, but it is estimated that 100 people are killed by rip currents annually. If caught in a rip current, don't fight it! Swim parallel to the shore and swim back to land at an angle.

While the terms are ofter confused, rip currents are different than rip tides. A rip tide is a specific type of current associated with the swift movement of tidal water through inlets and the mouths of estuaries, embayments, and harbors.

For more information:
NOAA Rip Current safety tips, surf forecasts
Coastal Currents Education Kit, NOS Education
Rip Current photos

Lionfish are native to the Indo-Pacific and Red Sea, but are now established along the eastern coast of the U.S. from Florida to North Carolina. They are also regularly found throughout the Bahamas and northern Caribbean, and have been sighted as far south as Nicaragua and as far east as the U.S. Virgin Islands.

How did the fish get to the Atlantic? While the exact cause is unknown, it's likely that humans provided a helping hand. Experts speculate that people have been dumping unwanted lionfish from home aquariums into the Atlantic Ocean for up to 25 years.

Since lionfish are not native to Atlantic waters, they have very few predators. They are also voracious predators that feed on small shrimp and large fish, including the young of important commercial fish species such as snapper and grouper.

Between 2000 and 2003, 49 lionfish sightings were reported at 16 different shipwrecks and natural hard-bottom locations. During a summer 2004 research expedition, NOAA scientists collected 155 lionfish at 19 different locations off the North Carolina coast alone. The jump in numbers and distribution over such a short time, plus sightings of juveniles smaller than those sold for aquaria, indicates that the lionfish is reproducing in the Atlantic Ocean. This marks the first time that a western Pacific fish has populated the waters of the U.S. Atlantic coast.

Unfortunately, NOAA researchers have concluded that invasive lionfish populations will continue to grow and cannot be eliminated using conventional methods. Marine invaders are nearly impossible to eradicate once established.

How lionfish will affect native fish populations and commercial fishing industries has yet to be determined. What is known is that non-native species can dramatically affect native ecosystems and local fishing economies. Experts are carefully studying these invaders to better understand the role their role in, and potential threat to, Atlantic Ocean ecosystems.

If you spot a lionfish, avoid it and report it. These fish have venomous spines that can be very painful. Scientists are also actively studying these fish to better understand the potential threat that lionfish pose to key reef and commercial fish species. Learning more about the habits and preferences of lionfish in non-native waters also helps experts determine where to look for these invasive fish.

For more information
"Responders Capture First Lionfish Invader in Sanctuary," NOS news
"The Lionfish Invasion," NOS Education
Report a Lionfish Sighting
Aquatic Invasive Species
Lionfish Sightings Distribution (U.S. Geological Survey)
Aquatic Nuisance Species Task Force

Winds blowing across the ocean surface push water away. Water then rises up from beneath the surface to replace the water that was pushed away. This process is known as “upwelling.”

Upwelling occurs in the open ocean and along coastlines. The reverse process, called “downwelling,” also occurs when wind causes surface water to build up along a coastline and the surface water eventually sinks toward the bottom.

Water that rises to the surface as a result of upwelling is typically colder and is rich in nutrients. These nutrients “fertilize” surface waters, meaning that these surface waters often have high biological productivity.  Therefore, good fishing grounds typically are found where upwelling is common.

For more information:
What Is Upwelling, Pacific Fisheries Environmental Laboratory
Upwelling, NOAA Ocean Explorer
Coastal Currents - Upwelling, NOS Education

As plants and animals near the surface of the ocean die and decay, they fall toward the sea floor, just like leaves and decaying material fall onto a forest floor. In addition to dead animals and plants, marine snow also includes fecal matter, sand, soot, and other inorganic dust.

The decaying material is referred to as “marine snow” because it looks a little bit like white fluffy bits.  The “snowflakes” grow as they fall, some reaching several centimeters in diameter. Some flakes fall for weeks before finally reaching the ocean floor.

This continuous rain of marine snow provides food for many deep-sea creatures. Many animals in the dark parts of the ocean filter marine snow from the water or scavenge it from the seabed.  Over the past 20 years or so, NOAA scientists and others have measured the amount of useable material in marine snow and found that there is plenty of carbon and nitrogen to feed many of the scavengers in the deep sea.

The small percentage of material not consumed in shallower waters becomes incorporated into the muddy “ooze” blanketing the ocean floor, where it is further decomposed through biological activity.  About three-quarters of the deep ocean floor is covered in this thick, smooth ooze.  The ooze collects as much as six meters (20 feet) every million years.  It is usually 289 meters (948 feet) thick, but can be up to nearly 10 kilometers (6.2 miles) thick.

For more information:
Marine Snow Video, NOAA Ocean Explorer

Soundings are water depth measurements that indicate how deep the water is in a particular area in either feet or fathoms. A fathom is a nautical unit of measurement and is equal to six feet.

On a chart, sounding data with the same values are usually connected with a line known as a depth contour, similar to the topographic lines or surface features that you see on a map. Depth contours present a picture of the bottom to the mariner.

A nautical chart is a graphic portrayal of the marine environment showing the nature and form of the coast, the general configuration of the sea bottom, including water depths, locations of dangers to navigation, locations and characteristics of human-made aids to navigation, and other features useful to the mariner.

For more information:
Office of Coast Survey
A History of Charting America's Waters, NOAA 200th Anniversary Web Site
Diving Deeper Podcast, Episode 5 (Mar. 23, 2009) - What is a nautical chart?
Nautical Charts: A Message in a Bottle, NOS Education

Nautical charts show what is in, under, and around the water, to help mariners transit our waters safely. The time it takes to develop a new nautical chart varies and it depends on the intensity of the ship travel in the area and the availability of resources to develop the new chart.

For example, if a new nautical chart is needed in an area that has current survey data, a new chart can be produced in six to 12 months. In a more remote area such as the north slope of Alaska, a new chart may take several years to develop because of the amount of survey work that needs to be done.

Another consideration in developing new nautical charts is the length of the survey season in different locations. The survey season is the time available to collect the data needed to develop a new chart. The survey season in Alaska is only a few months each year so it may take several years to collect the necessary data to develop a new chart. The Gulf of Mexico, on the other hand, can be surveyed during almost any time of the year.

It is easier to update existing nautical charts, but these updates can still be time and labor intensive. An estimate to complete an update for an existing chart is three to four weeks. Ports with high shipping activity, such as the Port of Long Beach or New York Harbor, may be updated as frequently as two or three times per year because of the intensity of traffic and the high value of cargo in these areas.

For more information:
Office of Coast Survey
A History of Charting America's Waters, NOAA 200th Anniversary Web Site
Diving Deeper Podcast, Episode 5 (Mar. 23, 2009) - What is a nautical chart?
Nautical Charts: A Message in a Bottle, NOS Education

Ocean water freezes just like freshwater, but at lower temperatures. Fresh water freezes at 0 degrees Celsius (32 degrees Fahrenheit), but seawater freezes at about -1.9 degrees Celsius (28.4 degrees Fahrenheit) because of the salt in it. When seawater freezes, however, the ice contains very little salt because only the water part freezes. It can be melted down to use as drinking water.

At least 15 percent of the ocean is covered by sea ice some part of the year. On average, sea ice covers almost about 25 million square kilometers (10 million square miles) of the Earth.

Sea water becomes more and more dense as it becomes colder, right down to its freezing point. Fresh water, on the hand, is most dense while still at 4 degrees Celsius (39.2 degrees Fahrenheit), well above the freezing point. The average temperature of all ocean water is about 3.5 degrees Celsius (38.3 degrees Fahrenheit).

For more information:
National Ice Center
NOAA's Arctic Theme Page
National Weather Service National Centers for Environmental Prediction: Sea Ice (sea ice data)
Salinity Data, National Oceanographic Data Center ]]> http://oceanservice.noaa.gov/facts/oceanfreeze.html Physical Properties Ocean Observations 6B0544B2-0FAE-4295-96D0-82BE82BF7BA1 Mon, 30 Mar 2009 08:08:53 -0400

Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea. Out in the depths of the ocean, tsunami waves do not dramatically increase in height. But as the waves travel inland, they build up to higher and higher heights as the depth of the ocean decreases. The speed of tsunami waves depends on ocean depth rather than the distance from the source of the wave. Tsunami waves may travel as fast as jet planes over deep waters, only slowing down when reaching shallow waters. While tsunamis are often referred to as tidal waves, this name is discouraged by oceanographers because tides have little to do with these giant waves.

For more information:
NOAA Deep-ocean Assesment and Reporting of Tsunamis (DART)
Map and Real-time DART Data
NOAA Tsunami Program
National Geophysical Data Center
NOAA Enhances Its Ability to Provide Tsunami Warnings (NOAA 200th Anniversary Web site)

]]> http://oceanservice.noaa.gov/facts/tsunami.html Oceanography Ocean Observations 6B73971F-D512-4D07-9427-6F7EE91129C1 Mon, 30 Mar 2009 08:07:56 -0400

Each year, three times as much rubbish is dumped into the world's oceans as the weight of fish caught.

Marine debris injures and kills marine life, interferes with navigation safety, and poses a threat to human health. Our oceans and waterways are polluted with a wide variety of marine debris ranging from soda cans and plastic bags to derelict fishing gear and abandoned vessels. 

Marine debris is defined as any persistent solid material that is manufactured or processed and directly or indirectly, intentionally or unintentionally, disposed of or abandoned into the marine environment or the Great Lakes.

Today, there is no place on Earth immune to this problem. A majority of the trash and debris that covers our beaches comes from storm drains and sewers, as well as from shoreline and recreational activities such as picnicking and beachgoing. Abandoned or discarded fishing gear is also a major problem because this trash can can entangle, injure, maim, and drown marine wildlife and damage property.

For more information:
NOAA Marine Debris Program
Coastal Management & Marine Debris, Office of Ocean & Coastal Resource Management

The Kuroshio Current, in the Pacific off the east coast of Taiwan extending northward off the east coast of Japan, is the ocean's largest current. It can travel between 40-121 kilometers per day (25-75 miles per day) at speeds between 1.6-4.8 kilometers per hour (about 1-3 miles per hour) and extends some 1,006 meters ( 3,300 feet) deep.

Ocean currents are driven by wind, temperature changes, and tides

Oceanic currents are driven by three main factors:

1. The rise and fall of the tides. Tides create a current in the oceans, near the shore, and in bays and estuaries along the coast. These are called "tidal currents." Tidal currents are the only type of currents that change in a very regular pattern and can be predicted for future dates.

2. Wind. Winds drive currents that are at or near the ocean's surface. These currents are generally measured in meters per second or in knots (1 knot = 1.85 kilometers per hour or 1.15 miles per hour). Winds drive currents near coastal areas on a localized scale and in the open ocean on a global scale.

3. Thermohaline circulation. This is a process driven by density differences in water due to temperature (thermo) and salinity (haline) variations in different parts of the ocean. Currents driven by thermohaline circulation occur at both deep and shallow ocean levels and move much slower than tidal or surface currents.

Currents affect the Earth's climate by driving warm water from the Equator and cold water from the poles around the Earth. The warm Gulf Stream, for instance, brings milder winter weather to Bergen, Norway, than to New York, much further south. It keeps the Norwegian coast an incredible 6.1 degrees Celsius (43 degrees Fahrenheit) warmer than other places equally far north.

Most ocean currents flow in one direction all the time. In the northern Indian Ocean, though, they change direction twice a year, driven by the monsoon winds. From November to March, the currents are blown towards Africa by the cool, dry north-east monsoon winds. In May, the winds blow in the opposite direction, driving the water towards India.

For more information:
Observations of the Gulf Stream, NOAA Ocean Explorer
NOAA CoastWatch
Tides & Currents: Center for Operational Oceanographic Products and Services
]]> http://oceanservice.noaa.gov/facts/current.html Currents Ocean Observations BBF4C54F-45A4-4E5E-9C18-DA7A4AC14E86 Mon, 30 Mar 2009 07:03:58 -0400

Human-made products are not completely biodegradable. These products will take a long time, possibly hundreds of years, to degrade. Some products such as glass never degrade. To determine how long it will take for debris to degrade depends on several factors such as material type, size, thickness, and environmental conditions (e.g., amount of exposure to sunlight or location - on the beach or floating at sea).

While photodegradable plastics (plastics capable of being broken down by light) may break down from its first state (or created state), these plastics never completely degrade, but actually divide into tiny pieces called microplastics. Microplastics are the multi-colored pieces of plastic that can be found in a handful of sand on the beach or in the ocean. Scientists are still investigating the impact of microplastics on our ocean and marine life.

For more information:
NOAA Marine Debris Program
Diving Deeper Podcast, Episode 3 (Feb. 23, 2009) - What is marine debris?

When it comes to eating, the ocean provides much more than just seafood. Many of the foods and products found in your local grocery store contain ingredients from the ocean.

For example, peanut butter and toothpaste both contain carrageenan. Carrageenan is a generic term for compounds extracted from species of red algae. Boiling the algae extracts the carrageean, which in turn is used to make peanut butter more spreadable. Carrageenan also gives toothpaste its consistency and is used in other cosmetics, pharmaceuticals, and industrial products.

For more information:
International Year of the Ocean – Ocean Exploration Fact Sheet

Reef-building corals cannot tolerate water temperatures below 64° Fahrenheit (18° Celsius). Many grow optimally in water temperatures between 73° and 84° Fahrenheit (23°–29°Celsius), but some can tolerate temperatures as high as 104° Fahrenheit (40° Celsius) for short periods.

Most reef-building corals also require very saline (salty) water ranging from 32 to 42 parts per thousand.

The water must also be clear so that a maximum amount of light penetrates it. This is because most reef-building corals contain photosynthetic algae, called zooxanthellae, which live in their tissues. The corals and algae have a unique relationship. The coral provides the algae with a protected environment and compounds they need for photosynthesis. In return, the algae produce oxygen and help the coral to remove wastes. Most importantly, zooxanthellae supply the coral with food. The algae need light in order to produce food via photosynthesis.

For more information:
Corals Tutorial, NOS Education
Coral Reef Biology, NOAA's Coral Reef Information System

The Gulf Stream is an intense, warm ocean current in the western North Atlantic Ocean. It moves north along the coast of Florida and then turns eastward off of North Carolina, flowing northeast across the Atlantic.

Off the Atlantic seaboard of the United States, the Gulf Stream flows at a rate nearly 300 times faster than the typical flow of the Amazon River. The velocity of the current is fastest near the surface, with the maximum speed typically about 5.6 miles per hour (nine kilometers per hour). The average speed of the Gulf Stream, however, is four miles per hour (6.4 kilometers per hour). The current slows to a speed of about one mile per hour (1.6 kilometers per hour) as it widens to the north.

For more information:
Observations of the Gulf Stream, NOAA Ocean Explorer
NOAA CoastWatch

Stretching for 1,600 miles (2,600 kilometers) over an area of approximately 133,000 square miles (344,400 square kilometers), the Great Barrier Reef is the largest coral reef system in the world. The reef is located off the coast of Queensland, Australia, in the Coral Sea.

The reef, which is large enough to be visible from space, is made up of nearly 3,000 individual reefs. Much of the Great Barrier Reef is a marine protected area, managed by the Great Barrier Reef Marine Park Authority of Australia.

For more information:
Great Barrier Reef Marine Park Authority
Coral Reef Conservation
NOAA Coral Reef Conservation Program

Many people use the terms "ocean" and "sea" interchangeably when speaking about the ocean, but there is a difference between the two terms when speaking of geography (the study of the Earth's surface).

Seas are smaller than oceans and are usually located where the land and ocean meet. Typically, seas are partially enclosed by land.

For more information:
Office of Coast Survey
A History of Charting America's Waters, NOAA 200th
Anniversary Web Site

The origins of the phrase 'Seven Seas' can be traced to ancient times.

In various cultures at different times in history, the Seven Seas has referred to bodies of water along trade routes, regional bodies of water, or exotic and far-away bodies of water.

In Greek literature (which is where the phrase entered Western literature), the Seven Seas were the Aegean, Adriatic, Mediterranean, Black, Red, and Caspian seas, with the Persian Gulf thrown in as a "sea."

In Medieval European literature, the phrase referred to the North Sea, Baltic, Atlantic, Mediterranean, Black, Red, and Arabian seas.

After Europeans 'discovered' North America, the concept of the Seven Seas changed again. Mariners then referred to the Seven Seas as the Arctic, the Atlantic, the Indian, the Pacific, the Mediterranean, the Caribbean, and the Gulf of Mexico.

Not many people use this phrase today, but you could say that the modern Seven Seas include the Arctic, North Atlantic, South Atlantic, North Pacific, South Pacific, Indian, and Southern Oceans.

However, our oceans are more commonly geographically divided into the Atlantic, Pacific, Indian, Arctic, and Southern (Antarctic) Oceans.

For more information:
How many oceans are there?
NOAA Nautical Charts
A History of Charting America's Waters, NOAA 200th Anniversary Web Site

There are over 1,700 marine protected areas (MPAs) in the United States established by federal, state, and territorial governments. These areas cover 34 percent of U.S. marine waters and vary widely in their purpose, legal authorities, managing agencies, and level of protection.

Although MPAs are found in every region of the United States, the West Coast, including California, Oregon, and Washington, has the highest number of MPAs.  However, the region with the largest area of MPAs is the Pacific Islands. This is because of the designation of the Papahānaumokuākea Marine National Monument, which is one of the largest marine conservation areas in the world.

For more information:
MPAs: Evolving Efforts to Manage Marine Resources, NOAA 200th Anniversary Web Site
Marine Protected Areas Center
Marine Protected Areas Virtual Library
Office of Ocean and Coastal Resource Management
MPA Case Studies
Diving Deeper: Marine Protected Areas

The Center for Operational Oceanographic Products and Services (CO-OPS) is primarily responsible for predicting and measuring water levels and currents and disseminating this information. CO-OPS collects, analyzes, and distributes such data to maintain safe maritime navigation and waterborne commerce.

While CO-OPS computes tidal predictions for more than 3,000 water-level stations around the United States, the publication of full daily predictions is limited to fewer stations. Stations with full daily predictions are called “reference stations” and remaining stations are called “subordinate stations.” You can calculate tidal predictions for subordinate stations by applying specific differences to the times and heights of tides of the specified reference stations.

For more information:
Water Level Tidal Predictions, Center for Operational Oceanographic Products and Services
Tides and Water Levels, NOS Education
Changing Technology for Real-Time Tide Measurements, NOAA 200th Anniversary Web Site

To be classified as an iceberg, the height of the ice must be greater than 16 feet (five meters) above sea level and the thickness must be 98-164 feet (30-50 meters) and the ice must cover an area of at least 5,382 square feet (500 square meters).

There are smaller pieces of ice known as “bergy bits” and “growlers.” Bergy bits and growlers can originate from glaciers or shelf ice, and may also be the result of a large iceberg that has broken up. A bergy bit is a medium to large fragment of ice. Its height is generally greater than three feet (one meter) but less than 16 feet (five meters) above sea level and its area is normally about 1,076-3,229 square feet (100-300 square meters). Growlers are smaller fragments of ice and are roughly the size of a truck or grand piano. They extend less than three feet (one meter) above the sea surface and occupy an area of about 215 square feet (20 square meters).

Icebergs are also classified by shape, most commonly being either tabular or non-tabular. Tabular icebergs have steep sides and a flat top. Non-tabular icebergs have different shapes, with domes and spires.

Icebergs are monitored worldwide by the U.S. National Ice Center (NIC). NIC produces analyses and forecasts of Arctic, Antarctic, Great Lakes, and Chesapeake Bay ice conditions. NIC is the only organization that names and tracks all Antarctic Icebergs.

For more information:
U.S. National Ice Center

Underwater volcanoes at spreading ridges and convergent plate boundaries produce hot springs known as hydrothermal vents.

Scientists first discovered hydrothermal vents in 1977 while exploring an oceanic spreading ridge near the Galapagos Islands. To their amazement, the scientists also found that the hydrothermal vents were surrounded by large numbers of organisms that had never been seen before. These biological communities depend upon chemical processes that result from the interaction of seawater and hot magma associated with underwater volcanoes.

Hydrothermal vents are the result of seawater percolating down through fissures in the ocean crust in the vicinity of spreading centers or subduction zones (places on Earth where two tectonic plates move away or towards one another). The cold seawater is heated by hot magma and reemerges to form the vents. Seawater in hydrothermal vents may reach temperatures of over 340°C (700°F).

Hot seawater in hydrothermal vents does not boil because of the extreme pressure at the depths where the vents are formed.

For more information:
Loihi Submarine Volcano: A Unique, Natural Extremophile Laboratory, NOAA Office of Oceanic and Atmospheric Research
Hydrothermal Vents Program, NOAA Pacific Marine Environmental Laboratory

"Extremophiles" are microorganisms with the ability to thrive in extreme environments such as hydrothermal vents.
Since they live in “extreme environments” (under high pressure and temperature), they can tell us under which range of conditions life is possible.

The unique enzymes used by these organisms, called "extremozymes," enable these organisms to function in such forbidding environments. These creatures hold great promise for genetically based medications and industrial chemicals and processes.

It's important to note that these organisms are 'extreme' only from a human perspective. While oxygen, for example, is a necessity for life as we know it, some organisms flourish in environments with no oxygen at all.

For more information:
Novel Microorganisms from the cold dark sea, NOAA Ocean Explorer
Loihi Submarine Volcano: A unique, natural extremophile laboratory, NOAA Office of Oceanic and Atmospheric Research
Hydrothermal Vents Program, NOAA Pacific Marine Environmental Laboratory

The concept of coastal zone management is a relatively new one, emerging less than four decades ago from the need to tackle an array of interconnected problems associated with population growth and development along our nation’s coasts.

The Coastal Zone Management Act (CZMA) was passed in 1972 and provided a formal structure to address the challenges of continued growth in coastal areas. Administered by NOAA, the CZMA recognizes that ensuring access to clean water and healthy ecosystems that support a vibrant coastal economy requires effectively integrating science, technology, and public policy. The goals of the CZMA are to “preserve, protect, develop, enhance, and restore where possible, the coastal resources.”

One program under the CZMA, the National Coastal Zone Management Program, encourages coastal states and territories to work in partnership with the federal government to design and enforce local programs consistent with the CZMA and accompanying regulations. Today, 34 of the 35 eligible coastal and Great Lakes states and territories have entered into the voluntary partnership.

As a result of the Coastal Zone Management Act and the success of its programs, coastal communities are equipped to better address continued economic development of the coastal zone while accounting for natural resource management. This will ensure the health and stability of the coast, both environmentally and economically, into the long-term future.

For more information:
Office of Ocean and Coastal Resource Management: Partnering with States to Manage Our Coastline
The Coastal Zone Management Act: A History of Treasuring Our Coastlines and Estuaries

Volcanic eruptions occur only in certain places and do not occur randomly. This is because the Earth’s crust is broken into a series of slabs known as tectonic plates. These plates are rigid, but they “float” on a hotter, softer layer in the Earth's interior. As the plates move, they spread apart, collide, or slide past each other.

Sixty percent of all active volcanoes occur at the boundaries between tectonic plates. Most volcanoes are found along a belt, called the “Ring of Fire” that encircles the Pacific Ocean. Some volcanoes, like those that form the Hawaiian Islands, occur in the interior of plates at areas called “hot spots.”

Although most of the active volcanoes we see on land occur where plates collide, the greatest number of the Earth's volcanoes are hidden from view, occurring on the ocean floor along spreading ridges.

For more information:
Teachers Guide to Stratovolcanoes of the World
New Zealand American Submarine Ring of Fire 2007, NOAA Ocean Explorer
Submarine Ring of Fire 2004, NOAA Ocean Explorer
'Kick'em Jenny' Volcano, NOAA Ocean Explorer

Rogue, freak, or killer waves have been part of marine folklore for centuries, but have only been accepted as a real phenomenon by scientists over the past few decades.

Rogues, called 'extreme storm waves' by scientists, are those waves which are greater than twice the size of surrounding waves, are very unpredictable, and often come unexpectedly from directions other than prevailing wind and waves.

Most reports of extreme storm waves say they look like "walls of water." They are often steep-sided with unusually deep troughs.

Since these waves are uncommon, measurements and analysis of this phenomenom is extremely rare. Exactly how and when rogue waves form is still under investigation, but there are several known causes:

Constructive interference. Extreme waves often form because swells, while traveling across the ocean, do so at different speeds and directions. As these swells pass through one another, their crests, troughs, and lengths sometimes coincide and reinforce each other. This process can form unusually large, towering waves that quickly disappear. If the swells are travelling in the same direction, these mountainous waves may last for several minutes before subsiding.

Focusing of wave energy. When waves formed by a storm develop in a water current against the normal wave direction, an interaction can take place which results in a shortening of the wave frequency. This can cause the waves to dynamically join together, forming very big 'rogue' waves. The currents where these are sometimes seen are the Gulf Stream and Agulhas current. Extreme waves developed in this fashion tend to be longer lived.

For more information:
Wind, Swell and Rouge Waves, JetStream Online School for Weather, National Weather Service
Rogue Waves, Ocean Prediction Center, National Weather Service

Life on Earth is found in conditions ranging from the coldest arctic ice to extremely hot hydrothermal systems on the ocean floor. Microbes are also found in very acidic conditions, very salty conditions, and very alkaline conditions.

These microbes are called “extremophiles” (which means 'lovers of extremes').

While conditions on the surface of the Earth where humans are happy are likely to be extremely rare outside of our home planet, the range of conditions in which microbes are found on Earth are more likely to be found on other planets and moons.

Some areas of our oceans, for example, may be similar to conditions found elsewhere in the solar system.

Jupiter’s moon Europa is completely covered by ice, but the tidal energy generated by giant Jupiter is so strong that a global ocean likely exists under the ice that could be 10 times as deep as what we find on Earth. Many scientists think that hydrothermal vents may exist at the bottom of this vast ocean.

This is exciting news, because microbes are found in abundance in hydrothermal vent systems in our oceans.

Understanding extreme life on Earth might help us identify environments on other moons and planets where life could exist.

For more information:
Novel Microorganisms from the Cold Dark Sea, NOAA Ocean Explorer
Loihi Submarine Volcano: A Unique, Natural Extremophile Laboratory, NOAA Office of Oceanic and Atmospheric Research
Hydrothermal Vents Program, NOAA Pacific Marine Environmental Laboratory

The highest tides in the world can be found in Canada at the Bay of Fundy, which separates New Brunswick from Nova Scotia.

At some times of the year the difference between high and low tide in this Bay is 16.3 meters (53.5 feet), taller than a three-story building.

Anchorage, Alaska, comes in at a close second with tidal ranges up to 12.2 meters (40 feet).

At increasing lattitudes (as one moves further from the equator and closer to the poles) there often is a dramatic increase in tidal range.

Tidal highs and lows depend on a lot of different factors. The shape and geometry of a coastline play a major role, as do the locations of the Sun and Moon. Storm systems at sea and on land also shift large quantities of water around and affect the tides. Detailed forecasts are available for high and low tides in all sea ports, but are specific to local conditions.

For more information:
Tides and Water Levels, NOS Education
Tides Online, Center for Operational Oceanographic Products and Services

Tides are one of the most reliable phenomena in the world. As the sun rises in the east and the stars come out at night, we are confident that the ocean waters will regularly rise and fall along our shores.

Tides are very long-period waves that move through the oceans in response to the forces exerted by the moon and sun. Tides originate in the oceans and progress toward the coastlines where they appear as the regular rise and fall of the sea surface.

When the highest part, or crest, of the wave reaches a particular location, high tide occurs; low tide corresponds to the lowest part of the wave, or its trough. The difference in height between the high tide and the low tide is called the tidal range.

For more information:
Tides and Water Levels, NOS Education
Tides Online, Center for Operational Oceanographic Products and Services

Most scientists agree that the atmosphere and the oceans accumulated gradually over millions and millions of years with the continual ‘degassing’ of the Earth’s interior.

According to this theory, the ocean formed from the escape of water vapor and other gases from the molten rocks of the Earth to the atmosphere surrounding the cooling planet.  

After the Earth's surface had cooled to a temperature below the boiling point of water, rain began to fall—and continued to fall for centuries. As the water drained into the great hollows in the Earth's surface, the primeval ocean came into existence. The forces of gravity prevented the water from leaving the planet.

While there is only one global ocean, the seas are geographically divided into the Atlantic, Pacific, Indian, Arctic, and Southern (Antarctic) Oceans.

These five oceans are not separate bodies of water; they form one continuous oceanic mass. The boundaries between these five oceans arose over time for a variety of historical, cultural, geographical, and scientific reasons.

The Pacific, the Atlantic and the Indian Oceans are known as the three major oceans.

The Southern Ocean is the 'newest' ocean. The boundaries of this ocean were set in 2000 by the International Hydrographic Organization. The U.S. is a member of this organization, represented by the NOS Office of Coast Survey.

For more information:
Office of Coast Survey
A History of Charting America's Waters, NOAA 200th Anniversary Web Site

Some people may think that because it is easier to hear in air than in water, then sound must travel faster in air. Actually, sound travels five times faster in water than in air.

The reason it is harder for humans to hear in water is because there are two different ways we hear: through air conductivity or vibrations in the audio bones from our inner ear, and through bone conductivity or vibrations in our skull. Bone conductivity is used to hear under water, but it is 40 percent less effective than air conductivity.

It is also harder to hear under water because when the outer portion of our ears fill up with water, the eardrums can’t vibrate.

For more information:
Understanding Ocean Acoustics, NOAA Ocean Explorer
Sound in the Sea Gallery, NOAA Ocean Explorer
Acoustic Monitoring, NOAA Vents Program

The ocean is blue because water absorbs colors in the red part of the light spectrum. Like a filter, this leaves behind colors in the blue part of the light spectrum for us to see.

The ocean may also take on green, red, or other hues as light bounces off of floating sediments and particles in the water.

Most of the ocean, however, is completely dark. Hardly any light penetrates deeper than 200 meters (656 feet), and no light penetrates deeper than 2,000 meters (3,280 feet ).

For more information:
Light Penetration in Water, NOAA's Ocean Explorer

It's hard to imagine, but an astounding 97 percent of the Earth's water can be found in our oceans. Of the tiny percentage that's not in the ocean, about two percent is frozen up in glaciers and ice caps. Less than one percent of all the water on Earth is fresh. A tiny fraction of water exists as water vapor in our atmosphere.

According to the U.S. Geological Survey, there are over 1,386,000,000 cubic kilometers (332,519,000 cubic miles) of water on the planet. A cubic kilometer is the volume of a cube measuring one kilometer on each side. Almost all of this vast volume of water is in the ocean.

That's 36,614,237,300,000,000,000,000 gallons of milk!

A nautical chart is one of the most fundamental tools available to the mariner. It's a graphic portrayal of the marine environment showing the nature and form of the coast, the general configuration of the sea bottom, including water depths, locations of dangers to navigation, locations and characteristics of human-made aids to navigation and other features useful to the mariner.

The nautical chart is essential for safe navigation. In conjunction with supplemental navigational aids, it is used by the mariner to lay out courses and navigate ships by the shortest and most economically safe route. Over 98 percent of the nation’s cargo is carried by waterborne transportation—and all of those ships rely on nautical charts to find their way.

For more information:
Office of Coast Survey
A History of Charting America's Waters, NOAA 200th Anniversary Web Site
Nautical Charts: A Message in a Bottle, NOS Education

Some areas of the ocean are saltier than others. This image shows methane mussels living at the edge of a underwater brine pool in a cavern at a depth of 198 meters (650 feet) in the Gulf of Mexico. The pool of brine in the foreground is nearly four times as salty as seawater and is so dense that a submarine can float on the pool (in fact, this photo was shot from a submarine).

Salt in the ocean comes from rocks on land. Here's how it works:

The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air. This causes the rainwater to be slightly acidic due to carbonic acid (which forms from carbon dioxide and water).

As the rain erodes the rock, acids in the rainwater break down the rock. This process creates ions, or electrically charged atomic particles. These ions are carried away in runoff to streams and rivers and, ultimately, to the ocean. Many of the dissolved ions are used by organisms in the ocean and are removed from the water. Others are not used up and are left for long periods of time where their concentrations increase over time.

Two of the most prevalant ions in seawater are chloride and sodium. Together, they make up over 90 percent of all dissolved ions in the ocean. Sodium and Chloride are 'salty.'

The concentration of salt in seawater (salinity) is about 35 parts per thousand. Stated in another way, about 3.5 percent of the weight of seawater comes from the dissolved salts; in a cubic mile of seawater, the weight of the salt (in the form of sodium chloride) would be about 120 million tons.

By some estimates, if the salt in the ocean could be removed and spread evenly over the Earth’s land surface it would form a layer more than 166 meters (500 feet) thick, about the height of a 40-story office building.

For more information:
Salinity Data, National Oceanographic Data Center (NODC)

Marine protected areas (MPAs) in the U.S. come in a variety of forms and are established and managed by all levels of government. There are marine sanctuaries, estuarine research reserves, ocean parks, and marine wildlife refuges. Each of these sites differs. MPAs may be established to protect ecosystems, preserve cultural resources such as shipwrecks and archaeological sites, or sustain fisheries production.

There is often confusion and debate regarding what the term “marine protected area” really means. Some people interpret MPAs to mean areas closed to all human activities, while others interpret them as special areas set aside for recreation (e.g., national parks) or to sustain commercial use (e.g., fishery management areas). These are just a few examples of the many types of MPAs.

In reality, “marine protected area” is a term that encompasses a variety of conservation and management methods in the United States. If you have been fishing in central California, diving near a shipwreck in the Florida Keys, camping in Acadia, snorkeling in the Virgin Islands, or hiking along the Olympic Coast, you were probably one of thousands of visitors to an MPA.

In the U.S., MPAs span a range of habitats, including the open ocean, coastal areas, inter-tidal zones, estuaries, and the Great Lakes. They also vary widely in purpose, legal authorities, agencies, management approaches, level of protection, and restrictions on human uses.

For more information:
MPAs: Evolving Efforts to Manage Marine Resources, NOAA 200th Anniversary Web Site
Marine Protected Areas Center
Marine Protected Areas Virtual Library
Office of Ocean and Coastal Resource Management
MPA Case StudiesExecutive Order 13158 on marine protected areas (pdf, 140kb)

Tides are driven by the gravitational force of the moon and sun. Tides are characterized by water moving up and down over a long period of time.

When used in association with water, the term "current" describes the motion of the water. Oceanic currents are driven by several factors. One is the rise and fall of the tides. Tides create a current in the oceans, near the shore, and in bays and estuaries along the coast. These are called "tidal currents." Tidal currents are the only type of currents that change in a very regular pattern and can be predicted for future dates.

A second factor that drives ocean currents is wind. Winds drive currents that are at or near the ocean's surface. These currents are generally measured in meters per second or in knots (1 knot = 1.85 kilometers per hour or 1.15 miles per hour). Winds drive currents near coastal areas on a localized scale and in the open ocean on a global scale.

A third factor that drives currents is thermohaline circulation - a process driven by density differences in water due to temperature (thermo) and salinity (haline) in different parts of the ocean. Currents driven by thermohaline circulation occur at both deep and shallow ocean levels and move much slower than tidal or surface currents.

For more information:
Currents, NOS Education
Tides and Currents
Major Ocean Currents, JetStream, the National Weather Service Online Weather School
Rip Currents, JetStream, the National Weather Service Online Weather School

Harmful algal blooms (HABs) occur when colonies of algae—simple ocean plants that live in the sea—grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals and birds.

While we know of many factors that may contribute to HABs, how these factors come together to create a 'bloom' of algae are not well understood.

Studies indicate that many algal species flourish when wind and water currents are favorable.

In other cases, HABs may be linked to 'overfeeding.' This occurs when nutrients (mainly phosphorus, nitrogen, and carbon) from sources such as lawns and farmlands flow downriver to the sea and build up at a rate that 'overfeeds' the algae that exist normally in the environment.

Some HABs have also been reported in the aftermath of natural phenomena like sluggish water circulation, unusually high water temperatures, and extreme weather events such as hurricanes, floods, and drought.

People often get sick by eating shellfish containing toxins produced by these algae. Airborne HAB toxins may also cause breathing problems and, in some cases, trigger asthma attacks in susceptible individuals.

HABs can also be costly in economic terms as well. At present, HABs cause about $82 million a year in economic losses to the seafood, restaurant, and tourism industries each year. HABs reduce tourism, close beaches and shellfish beds, and decrease the catch from both recreational and commercial fisheries.

NOAA scientists continue to monitor and study HABs to determine how to detect and forecast the location of the blooms. The goal is to give coastal communities advance warning, so they can adequately plan and deal with the adverse environmental and health effects associated with a harmful bloom.

For more information:
National Centers for Coastal Ocean Science (NCCOS)
Harmful Algal Blooms, NCCOS Center for Sponsored Coastal Research
Phytoplankton Monitoring Network, NCCOS Center for Coastal Environmental Health and Biomolecular Research
Harmful Algal Bloom Forecasting, NCCOS Center for Coastal Monitoring and Assessment

Harmful algal blooms, or HABs, occur when colonies of algae—simple ocean plants that live in the sea—grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals and birds. The human illnesses caused by HABs, though rare, can be debilitating or even fatal.

While many people call these blooms 'red tides,' scientists prefer the term harmful algal bloom. One of the best known HABs in the nation occurs nearly every summer along Florida’s Gulf Coast. This bloom, like many HABs, is caused by microscopic algae that produce toxins that kill fish and make shellfish dangerous to eat. The toxins may also make the surrounding air difficult to breathe. As the name suggests, the bloom of algae often turns the water red.

HABs have been reported in almost every U.S. coastal state, and their occurrence may be on the rise. HABs are a national concern because they affect not only the health of people and marine ecosystems, but also the 'health' of local and regional economies.

But not all algal blooms are harmful. Most blooms, in fact, are beneficial because the tiny plants are food for animals in the ocean. In fact, they are the major source of energy that fuels the ocean food web.

A small percentage of algae, however, produce powerful toxins that can kill fish, shellfish, mammals and birds, and may directly or indirectly cause illness in people. HABs also include blooms of non-toxic species that have harmful effects on marine ecosystems. For example, when masses of algae die and decompose, the decaying process can deplete oxygen in the water, causing the water to become so low in oxygen that animals either leave the area or die.

Scientists at the National Ocean Service have been monitoring and studying this phenomenon for a number of years to determine how to detect and forecast the location of the blooms. The goal is to give communities advance warnings so they can adequately plan for and deal with the adverse environmental and health affects associated with these 'red-tide' events.

For more information:
NOAA's National Centers for Coastal Ocean Science (NCCOS)
Harmful Algal Blooms, NCCOS Center for Sponsored Coastal Research
Phytoplankton Monitoring Network, NCCOS
Harmful Algal Bloom Forecasting, NCCOS Center for Coastal Monitoring and Assessment

Coral reefs are sometimes considered the medicine cabinets of the 21st century. Coral reef plants and animals are important sources of new medicines being developed to treat cancer, arthritis, human bacterial infections, Alzheimer’s disease, heart disease, viruses, and other diseases.

Since corals are stationary animals, many have evolved chemical defenses to protect themselves from predators. Scientists continue to research the medicinal potential of these substances. In the future, coral reef ecosystems could represent an increasingly important source of medical treatments, nutritional supplements, pesticides, cosmetics, and other commercial products.

For more information :
U.S. Coral Reef Task Force
Coral Reef Information System
International Year of the Reef
Coral Reef Conservation Program
Coral Health and Monitoring Program
Corals, NOS Education

Eighty percent of pollution to the marine environment comes from the land. One of the biggest sources is called nonpoint source pollution, which occurs as a result of runoff. Nonpoint source pollution includes many small sources, like septic tanks, cars, trucks, and boats, plus larger sources, such as farms, ranches, and forest areas. Millions of motor vehicle engines drop small amounts of oil each day onto roads and parking lots. Much of this, too, makes its way to the sea.

Some water pollution actually starts as air pollution, which settles into waterways and oceans. Dirt can be a pollutant. Top soil or silt from fields or construction sites can run off into waterways, harming fish and wildlife habitats.

Nonpoint source pollution can make river and ocean water unsafe for humans and wildlife. In some areas, this pollution is so bad that it causes beaches to be closed after rainstorms.

More than one-third of the shellfish-growing waters of the United States are adversely affected by coastal pollution.

Correcting the harmful effects of nonpoint source pollution is costly. Each year, millions of dollars are spent to restore and protect areas damaged or endangered by nonpoint source pollutants. NOAA works with the U.S. Environmental Protection Agency, Department of Agriculture, and other federal and state agencies to develop ways to control nonpoint source pollution. These agencies work together to monitor, assess, and limit nonpoint source pollution that may result naturally and by human actions.

NOAA's Coastal Zone Management Program is helping to create special nonpoint source pollution control plans for each coastal state participating in the program. When nonpoint source pollution does cause problems, NOAA scientists help track down the exact causes and find solutions.

For more information:
Nonpoint Source Pollution, NOS Education
Ocean and Coastal Resource Management Office
Coastal Zone Management

Sunlight entering the water may travel about 1,000 meters (3,280 feet) into the ocean under the right conditions, but there is rarely any significant light beyond 200 meters (656 feet).

The ocean is divided into three zones based on depth and light level. The upper 200 meters (656 feet) of the ocean is called the euphotic, or "sunlight," zone. This zone contains the vast majority of commercial fisheries and is home to many protected marine mammals and sea turtles.

Only a small amount of light penetrates beyond this depth.

The zone between 200 meters (656 feet) and 1,000 meters (3,280 feet) is usually referred to as the “twilight” zone, but is officially the dysphotic zone. In this zone, the intensity of light rapidly dissipates as depth increases. Such a miniscule amount of light penetrates beyond a depth of 200 meters that photosynthesis is no longer possible.

The aphotic, or “midnight,” zone exists in depths below 1,000 meters (3,280 feet). Sunlight does not penetrate to these depths and the zone is bathed in darkness.

‘Photic’ is a derivative of ‘photon,’ the word for a particle of light.

For more information:
Light Penetration in Water, NOAA's Ocean Explorer

Coastal areas are home to a wealth of natural and economic resources and are the most developed areas in the nation. The narrow fringe comprising 17 percent of the contiguous U.S. land area is home to more than half of the nation's population.

Between the years 1980 and 2003, population in coastal counties increased by 33 million people or by 28 percent. The largest gain was seen in the Pacific region. Additionally, in 2003, 23 of the 25 most densely populated counties were in coastal areas.

By the year 2008, coastal county population was expected to increase by approximately seven million.

For more information:
Population Trends Along the Coastal United States: 1980-2008<

The ocean is the lifeblood of Earth, covering more than 70 percent of the planet's surface, driving weather, regulating temperature, and ultimately supporting all living organisms. Throughout history, the ocean has been a vital source of sustenance, transport, commerce, growth, and inspiration.

Yet for all of our reliance on the ocean, 95 percent of this realm remains unexplored, unseen by human eyes.

NOAA’s Office of Ocean Exploration and Research is leading efforts to explore the ocean by supporting expeditions to investigate and document unknown and poorly known areas of the ocean. These expeditions represent a bold and innovative approach by infusing teams of scientist-explorers with a "Lewis and Clark" spirit of discovery and equipping them with the latest exploration tools.

From mapping and describing the physical, biological, geological, chemical, and archaeological aspects of the ocean to understanding ocean dynamics, developing new technologies, and helping us all unlock the secrets of the ocean, NOAA is working to increase our understanding of the ocean realm.

For more information:
NOAA Ocean Explorer

A nautical chart provides a very detailed and accurate representation of the coastline, which takes into account varying tidal levels and water forms, critical to a navigator.

A map, on the other hand, emphasizes land forms, with shoreline represented much less accurately.

A chart is continually updated and is used by navigators to plot courses. A map, on the other hand, is a static document which serves as a reference guide.

Nautical charts also provide detailed information on the area beneath the water surface, which is critical for safe and efficient navigation. Maps provide no information of the condition of a road.

For more information:
Office of Coast Survey
Nautical Charts: A Message in a Bottle, NOS Education

Sonar, short for Sound Navigation and Ranging, is helpful for exploring and mapping the ocean because sound waves travel farther in the water than do radar and light waves.

NOAA scientists primarily use sonar to develop nautical charts, locate underwater hazards to navigation, search for and map objects on the sea floor such as shipwrecks, and map the sea floor itself.

There are two types of sonar—active and passive.

Active sonar transducers* emit an acoustic signal or pulse of sound into the water. If an object is in the path of the sound pulse, the sound bounces off the object and returns an “echo” to the sonar transducer. If the transducer is equipped with the ability to receive signals, it measures the strength of the signal. By determining the time between the emission of the sound pulse and its reception, the transducer can determine the range and orientation of the object.

*A transducer is an electrical device that transforms energy from one form to another. Examples are microphones, antenna, and speakers.

Passive sonar systems are used primarily to detect noise from marine objects (such as submarines or ships) and marine animals like whales. Unlike active sonar, passive sonar does not emit its own signal, which is an advantage for military vessels that do not want to be found or for scientific missions that concentrate on quietly “listening” to the ocean. Rather, it only detects sound waves coming towards it. Passive sonar cannot measure the range of an object unless it is used in conjunction with other passive listening devices. Multiple passive sonar devices may allow for triangulation of a sound source.

For more information:
Surveys and Wrecks, Office of Coast Survey
Understanding Ocean Acoustics, NOAA Ocean Explorer
Sound in the Sea Gallery, NOAA Ocean Explorer
Acoustic Monitoring, NOAA Vents Program
Sonar, NOAA Ocean Explorer
Using Sonar to Detect Sea Turtles, NOS Weekly News

Coral reefs are home to millions of species. Hidden beneath the ocean waters, coral reefs teem with life. Fish, corals, lobsters, clams, seahorses, sponges, and sea turtles are only a few of the thousands of creatures that rely on reefs for their survival.

Coral reefs are also living museums and reflect thousands of years of history. Many U.S. coral reefs were alive and thriving centuries before the European colonization of the nearby shores. Some reefs are even older than our old-growth redwood forests. They are an integral part of many cultures and our natural heritage.

Today, these important habitats are threatened by a range of human activities. Many of the world’s reefs have already been destroyed or severely damaged by water pollution, overfishing and destructive fishing practices, disease, global climate change, and ship groundings. However, we can still protect and preserve our remaining reefs by acting now.

For More Information:
U.S. Coral Reef Task Force
Coral Reef Information System
International Year of the Reef
Coral Reef Conservation Program
Coral Health and Monitoring Program
Coral resources (for students and teachers)

Hydrography is the science that deals with the measurement and description of the physical features of bodies of water and the land areas that are affected by those bodies of water.

A hydrographic survey may be conducted to support a variety of activities: nautical charting, port and harbor maintenance (dredging), coastal engineering (beach erosion and replenishment studies), coastal zone management, and offshore resource development.

The one data type common to all hydrographic surveys is water depth. Of additional concern to most surveys is the nature of the sea-floor material (i.e., sand, mud, rock) due to its implications for anchoring, dredging, structure construction, pipeline and cable routing, and fisheries habitat.

The primary use of hydrographic surveys is for nautical charting.

For more information:
Office of Coast Survey
Sea-floor Mapping, NOS Education

The U.S. economy is very dependent on the health of the ocean. Consider the following facts: Through the fishing and boating industry, tourism and recreation, and ocean transport, one out of six jobs in the U.S. is marine-related.

Trade across the ocean contributes over $700 billion annually to the U.S. gross domestic product while employing 13 million Americans. Coastal and marine waters support over 28 million jobs, while providing tourist destinations for 189 million Americans each year. U.S. consumers spend over $55 billion for fishery products annually.

For more information:
NOAA's Coastal and Ocean Resource Economics

You may be surprised to learn that the National Ocean Service is responsible for surveying in support of the nation's airports and airspace.

NOAA has played a role in our nation's aviation industry since the early 1900s. Today, the National Geodetic Survey (part of NOS) administers the Aeronautical Survey Program. This program provides highly accurate position, height, and orientation information needed for safe air navigation.

NGS has been performing aeronautical surveys since the 1920s. These surveys provide critical information about airport features and about obstructions and aids to navigation. The Federal Aviation Administration uses this information to establish airport approach and departure procedures, determine maximum takeoff weights, update aeronautical publications, and conduct airport planning and construction studies.

For more information:

National Geodetic Survey (NGS)
NGS Aeronautical Survey Program
NGS Aeronautical Survey Program photo gallery (airports around the nation)
Are We Cleared To Land? The Wright Brothers Help NOAA Show The Way

The ocean plays an important role in shaping our climate and weather patterns.

Warm ocean waters provide the energy to fuel storm systems that provide fresh water vital to all living things. Understanding and predicting precipitation is critical to farmers who decide which crops to plant, and how deep, based in part on soil moisture levels. Crop and food prices may increase when weather that is too wet or too dry adversely affects crops.

Like precipitation, extreme heat and cold also affect livestock management.

Weather prediction can be a life-saving tool. Aside from helping people prepare for catastrophic storms, prediction can help citizens and governments anticipate extreme hot and cold temperatures, which may cause death among the elderly.

Water management experts study how much rainfall to anticipate so they can manage reservoir levels and water usage, to ensure everyone has abundant water supplies.

For more information:
National Weather Service
NOAA's Climate Prediction Center
The History of Numerical Weather Prediction , NOAA 200th Anniversary Web Site

There is strong evidence that global sea level is now rising at an increased rate and will continue to rise during this century.

While studies show that sea levels changed little from AD 0 until 1900, sea levels began to climb in the 20th century.

The two major causes of global sea-level rise are thermal expansion caused by the warming of the oceans (since water expands as it warms) and the loss of land-based ice (such as glaciers and polar ice caps) due to increased melting.

Records and research show that sea level has been steadily rising at a rate of 1 to 2.5 millimeters (0.04 to 0.1 inches) per year since 1900.

This rate may be increasing. Since 1992, new methods of satellite altimetry (the measurement of elevation or altitude) indicate a rate of rise of 3 millimeters (0.12 inches) per year.

This is a significantly larger rate than the sea-level rise averaged over the last several thousand years.

For more information:
Sea Levels Online, Center for Operational Oceanographic Products and Services
Global Warming: Frequently Asked Questions, NOAA National Climatic Data Center
Warming of the World Ocean, NOAA 200th Anniversary Web Site
Sea level rise, NOAA Science on a Sphere®

The coral reef structure buffers shorelines against waves, storms and floods, helping to prevent loss of life, property damage and erosion. When reefs are damaged or destroyed, the absence of this natural barrier can increase the damage to coastal communities from normal wave action and violent storms.

Several million people live in U.S. coastal areas adjacent to or near coral reefs. Some coastal development is required to provide necessary infrastructure for coastal residents and the growing coastal tourism industry.

However, the impacts of coastal development (e.g., marina, dock and bridge construction, dredging to replenish beaches) and polluted runoff from coastal areas can damage coral reefs over the long-term. Therefore, the health of coral reefs depends on sustainable coastal development practices that protect sensitive coral ecosystems and the creatures that reside there.

For more information:
U.S. Coral Reef Task Force
Coral Reef Information System
International Year of the Reef
Coral Reef Conservation Program
Coral Health and Monitoring Program
Coral resources (for students and teachers)

The longest mountain range on Earth is called the mid-ocean ridge. Spanning 65,000 kilometers (40,389 miles) around the globe, it's truly a global landmark.

About 90 percent of the mid-ocean ridge system is under the ocean. This system of mountains and valleys criss-crosses the globe, resembling the stitches in a baseball. It's formed by the movement of the Earth's tectonic plates.

As the great plates push apart, mountains and valleys form along the sea floor as magma rises up to fill the gaps. As the Earth's crust spreads, new ocean floor is created. This process literally renews the surface of our planet.

If you look at a map of the world's volcanoes, you'll find that most of them form along the boundaries of this great system. In fact, the global mid-ocean ridge system forms the largest single volcanic feature on the Earth. The mid-ocean ridge consists of thousands of individual volcanoes or volcanic ridge segments which periodically erupt.

For more information:
Submarine Ring of Fire, NOAA's Ocean Exlporer
NOAA's Office of Ocean Exploration
NOAA's Vents Program (undersea volcano and hydrothermal venting research)

The term benthic refers to anything associated with or occurring on the bottom of a body of water. The animals and plants that live on or in the bottom are known as the benthos.

In ocean waters, nearshore and estuary areas are most frequently mapped. This is partly because the areas are shallow enough to map, but also because these areas are very important to preserve and manage.

Benthic habitat maps are derived from aerial imagery, underwater photos, acoustic surveys, and data gathered from sediment samples. The resulting digital map is viewed using geographic information system tools.

Policy makers, scientists, and researchers use benthic maps to make informed decisions that help protect the nation’s fragile shallow-water coastal areas.

For more information:br> Benthic Habitat Mapping, NOAA Coastal Services Center (CSC)
Center for Coastal Monitoring and Assessment Biogeography Branch

Estuaries and their surrounding wetlands are bodies of water usually found where rivers meet the sea. Estuaries are home to unique plant and animal communities that have adapted to brackish water — a mixture of fresh water draining from the land and salty seawater.

Estuaries are among the most productive ecosystems in the world. Many animals rely on estuaries for food, places to breed, and migration stopovers.

Human communities also rely on estuaries for food, recreation, jobs, and coastal protection. Of the 32 largest cities in the world, 22 are located on estuaries!

Estuaries are delicate ecosystems. Congress created the National Estuarine Research Reserve System to protect more than one million acres of estuarine land and water. These estuarine reserves provide essential habitat for wildlife, offer educational opportunities for students, and serve as living laboratories for scientists.

For more information:
Esturaries.Gov
National Estuarine Research Reserve System
Estuaries, NOS Education

Covering over 70 percent of the Earth’s surface, the ocean represents our planet’s largest habitat, containing 99 percent of the living space on the planet. This vast area supports the life of nearly 50 percent of all species on Earth.

Scientists are currently conducting the first ever “Census of Marine Life,” to assess and explain the diversity, distribution, and abundance of life in the ocean. Expected to be completed in 2010, this project will be the first to develop a comprehensive global list of all forms of life in the ocean. Additionally, scientists estimate that perhaps a million or more species remain unknown, yet to be discovered.

Biological productivity of the ocean plays a vital role in the global climate and carbon cycle and provides nearly 50 percent of Earth's oxygen and 20 percent of the world's protein supply. Species from the ocean are also potential sources of new medicines.

For more information:
NOAA: Ocean
Census of Marine Life

Healthy coral reefs support commercial and subsistence fisheries as well as jobs and businesses through tourism and recreation. Approximately half of all federally managed fisheries depend on coral reefs and related habitats for a portion of their life cycles. The National Marine Fisheries Service estimates the commercial value of U.S. fisheries from coral reefs is over $100 million.

Local economies also receive billions of dollars from visitors to reefs through diving tours, recreational fishing trips, hotels, restaurants, and other businesses based near reef ecosystems.

Despite their great economic and recreational value, coral reefs are severely threatened by pollution, disease, and habitat destruction. Once coral reefs are damaged, they are less able to support the many creatures that inhabit them. When a coral reef supports fewer fish, plants, and animals, it also loses value as a tourist destination.

For more information:
U.S. Coral Reef Task Force
Coral Reef Information System
International Year of the Reef
Coral Reef Conservation Program
Coral Health and Monitoring Program
Corals, NOS Education

The average depth of the ocean is about 4,267 meters (14,000 feet). The deepest part of the ocean is called the Challenger Deep and is located beneath the western Pacific Ocean in the southern end of the Mariana Trench, which runs several hundred kilometers southwest of the U.S. territorial island of Guam. Challenger Deep is approximately 11,030 meters (36,200 feet) deep. It is named after the British survey ship Challenger II, which first surveyed the trench in 1951.

For more information:
Soundings, Sea-Bottom, and Geophysics, NOAA's Ocean Explorer