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Diving Deeper Shorts: Episode 1 (July 29, 2010) -

Dead Zone

HOST: Welcome to the first episode of Diving Deeper Shorts, where we highlight a few minutes of your favorite Diving Deeper episodes.

Today we will revisit our previous interview on dead zones and hypoxia with Dr. Rob Magnien from NOAA’s Center for Sponsored Coastal Ocean Research.

Let’s listen in.

HOST: Rob, what is hypoxia?

ROB MAGNIEN: Hypoxia is areas of our estuaries, coasts, or oceans with low levels or no oxygen dissolved in the water. These areas are often referred to as “dead zones” since most marine life either dies, or, if they are mobile such as fish, leave the area. Thus, habitats that would normally be teaming with life become, essentially, biological deserts.

HOST: What causes a dead zone or hypoxia to occur?

ROB MAGNIEN: Hypoxic zones can occur naturally, but the ones we are most concerned about are those created or enhanced by human activity. There are many physical, chemical, and biological factors that conspire to create dead zones, but nutrient pollution is the primary cause of those created by humans. Excess nutrients that run off land or are piped as wastewater into our 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.

HOST: Where do dead zones occur in the U.S.?

ROB MAGNIEN: Kate, 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 for that matter, that is immune. The second largest dead zone in the world is located right here in the U.S. in the northern Gulf of Mexico and the ones in the Chesapeake Bay and Lake Erie are not far behind in size.

That’s all for today’s Diving Deeper Shorts.

Want to learn more? Go to and select the July 2009 podcast archive to listen to the full interview with Dr. Magnien on dead zones.

You can catch the next episode of Diving Deeper in August.