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Healthy coral reefs, like this one in Swains Island in American Samoa, support an impressive array of marine life.

Coral reefs: Essential and threatened

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What are coral reefs?
Coral reefs: One of Earth’s most diverse ecosystems
Healthy reefs are valuable to you
Challenges for coral reefs are both local and global
A hands-on approach to reef conservation

Healthy coral reefs are one of the most valuable ecosystems on Earth. They provide billions of dollars in economic and environmental services, such as food, coastal protection and tourism. However, coral ecosystems face serious threats, mainly from the effects of global climate change, unsustainable fishing and land-based pollution.

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.

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 more than 800 known species of reef-building coral worldwide and hundreds of species of soft corals and deep-sea corals.

Coral reef​s ​​​​in the clear blue waters of Kure Atoll in ​Hawaii's Papahānaumokuākea Marine National Monument​.
Coral reef​s ​​​​in the clear blue waters of Kure Atoll in ​Hawaii's Papahānaumokuākea Marine National Monument​. (NOAA)

Coral reefs are also living museums and reflect thousands of years of history. Many U.S. coral reefs were alive and thriving centuries ago. 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 pollution, unsustainable fishing practices, disease, global climate change, ship groundings and other impacts. However, we can still protect and preserve our remaining reefs for future generations if we act now.

Healthy coral reefs are among Earth’s most biologically diverse and economically valuable ecosystems and are vital around the world.

Healthy coral reefs and their habitats are important to life in the ocean and on land. 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.

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. (Joe Hoyt/NOAA)

Approximately 500 million people worldwide depend upon reefs for food and their livelihoods, and 30 million are almost totally dependent upon reefs. 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.

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.

NOAA is working to understand and address 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 land-based 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, exacerbate each other.

Bleached corals on a reef at Lisianski Atoll in Papahanaumokuakea Marine National Monument.
Bleached corals on a reef at Lisianski Atoll in Papahanaumokuakea Marine National Monument. (Courtney Couch/NOAA)

Climate change affects coral reef ecosystems by increasing sea surface temperatures and leads to coral bleaching, disease, sea level rise and storm activity. Additionally, increased  carbon dioxide in the atmosphere changes ocean chemistry and harms reef-building corals.

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.

The effects of land-based sources of pollution, such as coastal development and agricultural runoff, can impede coral growth and reproduction, disturb ecological function and cause disease.

Although 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 equally important.

NOAA’s research is critical to increasing what we as a nation know about the causes of reef decline and how to address these challenges.

Through the activities of the Coral Reef Conservation Program, NOAA is doing what it can to address key threats that affect 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.

NOAA diver Kelly Gleason injects a crown-of-thorns starfish. Divers inject the central disk near an arm of each starfish with ox bile, a natural substance that kills the creature but does no harm to the reef.
NOAA diver Kelly Gleason injects a crown-of-thorns starfish, a species known to threaten coral. Divers inject the central disk near an arm of each starfish with ox bile, a natural substance that kills the creature, but does no harm to the reef. (Greg McFall, NOAA)

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, such as using less water and recycling or disposing of trash responsibly, can have big and far-reaching effects.    

You can learn more about NOAA's coral reef program at our Coral Reef Conservation Program website.

Published on
April 14, 2016