Coral Reefs

The Rainforests of the Ocean

What are coral reefs?

Pearl and Hermes Atoll lies about 216 nautical miles (400 km) east-southeast of Midway Atoll and approximately 1,080 nautical miles (2,000 km) northwest of Honolulu. It is a huge oval coral reef within several internal reefs. It is the second largest (about 1,166 km2 to depths of 100 meters) among the six atolls in the Northwestern Hawaiian Islands.

Did you know approximately 500 million people worldwide depend upon reefs for food and their livelihoods, and 30 million are almost totally dependent upon reefs?

Hidden beneath the ocean waters, coral reefs teem with life. Coral reefs support more species than any other marine environment and rival rainforests in their biodiversity. Countless numbers of creatures rely on coral reefs for their survival.

Corals are animals, even though they may exhibit some of the characteristics of plants and are often mistaken for rocks. In scientific classification, corals fall under the phylum Cnidaria and the class Anthozoa. They are relatives of jellyfish and anemones. There are over 800 known species of reef­building coral worldwide and hundreds of species of soft corals and deep-sea corals.

Although individual coral polyps are tiny, they create the largest living structures on earth—some reefs are visible from space!

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.

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 an increasing array of threats, including pollution, unsustainable fishing practices, and global climate change. As a result, 22 species of coral are now listed as threatened under the Endangered Species Act. However, we can still protect and preserve our remaining reefs if we act now. NOAA is leading U.S. efforts to study and conserve these precious resources for future generations.

Why are coral reefs important?

Coral reefs, like this one in Cordell Bank National Marine Sanctuary support an impressive array of marine life.

Coral reefs, like this one in Cordell Bank National Marine Sanctuary support an impressive array of marine life.

Healthy coral reefs are among the most biologically diverse and economically valuable ecosystems on earth, providing vital ecosystem services to people across the globe.

Coral reefs are an important habitat. 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, but so do humans.

In addition to supporting an abundance of marine life, coral reef ecosystems provide people with many goods and services, including shoreline protection. Coral ecosystems are a source of food for millions; protect coastlines from storms and erosion; provide habitat, spawning, and nursery grounds for economically important fish species; provide jobs and income to local economies from fishing, recreation, and tourism; are a source of new medicines; have cultural significance; and are hotspots of marine biodiversity.

The benefits of healthy reefs are seen not just in the ocean, but also on land. Coral reefs contribute billions of dollars to world economies each year. The continued decline and loss of coral reef ecosystems will have significant social, cultural, economic and ecological impacts on people and communities in the U.S. and around the world.

What threatens coral reefs?

Bleached corals on a reef at Lisianski Atoll in Papahānaumokuākea Marine National Monument.

Bleached corals on a reef at Lisianski Atoll in Papahānaumokuākea Marine National Monument.

NOAA focuses on understanding and addressing key threats to coral reef ecosystems: the impacts from global climate change, unsustainable fishing practices and pollution. The top threats to coral reefs, global climate change, unsustainable fishing, and land­based pollution, are all due to human activities. These threats—combined with others such as tropical storms, disease outbreaks, vessel damage, marine debris and invasive species—compound each other.

Climate change impacts coral reef ecosystems through increased sea surface temperatures that lead to coral bleaching events and disease, sea level rise and storm activity. Additionally, increasing atmospheric carbon dioxide alters ocean chemistry and negatively impacts reef-building corals.

An estimated 20 percent of the world's coral reefs are damaged beyond recovery and about half of the remaining coral reefs are under risk of collapse.

Unsustainable fishing practices in coral reef areas can lead to the loss of ecologically and economically important fish species. Such losses often have a ripple effect not just on the coral reef ecosystems themselves, but also on the local economies that depend on them.

Impacts from land-based sources of pollution (e.g., coastal development and agricultural runoff) can impede coral growth and reproduction, disturb ecological function, and cause disease.

While some of the biggest threats facing coral reefs are global in nature and require action on a similar scale, addressing local stressors—like reducing runoff and promoting sustainable fishing—is key.

Coral reef science and conservation.

10 ways you can help to protect coral reefs

Explore 10 ways that you can help to protect valuable coral reefs.

Through the activities of the Coral Reef Conservation Program, NOAA is doing its part to address key threats that impact coral reefs. Our work takes into account the inextricable connections coral reefs have to the lands they surround and the communities and economies they support.

From coral mapping, monitoring, and modeling to on-the-ground and in-water restoration activities, NOAA is leading ridge-to-reef efforts to support the management and conservation of these valuable ecosystems.

The Coral Reef Conservation Program coordinates NOAA’s role as the co-chair of the U.S. Coral Reef Task Force, a body that provides a forum for partnership on U.S. government work to protect coral reefs. The program also leads U.S. efforts abroad to enhance coral reef ecosystem management.

Although NOAA research is critical to increasing what we know about the causes of reef decline, effective coral reef conservation can’t happen without you. Even if you live far from a coral reef, you can contribute to their conservation. Simple actions, like using less water and recycling or disposing of trash responsibly, can have big and far-reaching impacts.