Shallow Coral Reef Habitat | NOAA Fisheries

Shallow Coral Reef Habitat | NOAA Fisheries
Shallow Coral Reef Habitat
Coral reefs are underwater structures built by tiny sea animals. Their beautiful shapes and colors are a magnet for divers. They also provide an excellent home for thousands of marine creatures, including fish we love to eat.
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On This Page
Coral Reefs: Rainforests of the Sea
Benefits of Shallow Coral Reefs
Challenges for Shallow Corals
What We Do
What You Can Do
More Information
Image
Corals create a rich habitat for sea life of all kinds. Here, a whitespot hawkfish peers out from a perch in the plating rice coral at Swains Island in American Samoa. Credit: NOAA Fisheries.
Coral Reefs: Rainforests of the Sea
Coral reefs
are the most diverse habitats on the planet. Reefs occur in less than 1 percent of the ocean, yet are
home to nearly one-quarter of all ocean species
. These ancient structures make a perfect home for fish, crabs, clams, starfish, squid, sponges, lobsters, seahorses, sea turtles, and more. That exceptional diversity has given them the nickname "rainforests of the sea."
While corals may look like plants or rocks, they are in fact animals that take root on the ocean floor. You can think of them as small jellyfish, glued inside a little rock cave. Their small, soft bodies, called polyps, built that cave—a strong skeleton of calcium carbonate—like a clam grows its shell.
Inside the polyp’s body live tiny one-celled algae, called a zooxanthella. This creature contains chlorophyll and, like plants, turns sunlight into sugar. By producing food and oxygen for the polyp, the zooxanthella gets a safe home. That’s why coral reefs need to be in clean, sunlit waters.
Corals have been on earth for at least 400 million years. Coral colonies create the structure of the reef, growing at a typical rate of 0.008 to 0.12 inches per year. Mature coral reefs can be thousands of years old and as big as a small car.
Shallow corals prefer clear, warm, moving water in subtropical and tropical seas. In the United States, you’ll find shallow coral reefs in:
American Samoa
Florida
Guam
Hawaii
Northern Mariana Islands
Pacific Remote Islands Areas
Puerto Rico
U.S. Virgin Islands
Image
Coral reef ecosystem at Palmyra Atoll National Wildlife Refuge. Credit: U.S. Fish and Wildlife Service.
Benefits of Shallow Coral Reefs
Coral reefs support a multitude of benefits—called ecosystem services—that impact our day-to-day lives. They provide jobs, seafood, opportunities for tourism and recreation, and more. In total, coral reefs in the United States provide
$1.75 billion in ecosystem services
. This includes employment, fisheries activity, and protection from storm surges and destructive waves.
Tourism
Coral reefs draw 55 million visitors every year to U.S. states, territories, and
marine sanctuaries
. In Hawaii, 60 percent of the state's tourist income comes from reef visitors.
Sustainable Fisheries
Many commercially important fish species like grouper, snapper, and lobster depend on coral reefs for food and shelter. Fish that grow and live on coral reefs are a significant food source for billions of people worldwide.
Reef-related fisheries in the United States are valued at
more than $100 million
. Half of all U.S. fisheries depend on healthy coral reefs. In Florida, where many fisheries depend on reef-raised species, an
estimated $28.7 billion in sales
come from commercial and recreational fishing industries.
Employment
From hotel rooms to dive trips, from clothing and gear to sport fishing, coral reefs support jobs for American workers. In southeast Florida alone, coral reefs
generate $324 million
in annual local sales and support more than 70,000 jobs. Hawaii attributes $304 million directly to reef tourism and recreation.
Storm Barriers
Reefs provide natural breakwaters, which buffer shorelines from waves and storms. Their rough surfaces and complex structures dissipate the force of incoming waves. This helps prevent flooding, erosion, property damage, and loss of life.
Medical Discoveries
Coral ecosystems are an
important source of new medicines
. For example, anti-cancer drugs are derived from certain marine algae, the mucus of cone snails yields a potent painkiller, and a
deep-sea sponge
shows promise in the treatment of pancreatic cancer.
Image
A bleached coral on a reef off of Islamorada, Florida. Credit: Kelsey Roberts/U.S. Geological Survey.
Challenges for Shallow Corals
Despite their great economic and recreational value, coral reefs are threatened throughout the world. In the Caribbean, elkhorn and staghorn coral populations have declined by more than 90 percent in the last 25 years. In Florida, an ongoing
multi-year outbreak of stony coral tissue loss disease
is impacting the continental United States' only living barrier reef.
Threats to coral reefs include:
Pollution from land runoff
Oil and chemical spills
Marine debris, trash, and plastic
Sedimentation
Nutrient pollution from fertilizers and sewage
Bottom-trawling and overfishing
Invasive species
Disease
Rising water temperature
Ocean acidification
Vessel groundings
Unsafe diving and boating habits
Once reefs are damaged, they become less productive. Fewer reef residents means less food for young fish, and that leads to declining fisheries. With the loss of colorful marine life, snorkeling and scuba-diving tourists stay away, and the local economy suffers.
Ocean Acidification
When carbon dioxide is absorbed into the ocean from the atmosphere, it
causes seawater to become more acidic
. This dissolves the shells of ocean creatures like corals, and decreases the rate at which they’re able to rebuild. The reef grows more fragile and less able to protect its residents.
Coral Bleaching
Prolonged high water temperatures can cause coral polyps to expel their symbiotic partners, the tiny algae that help them produce food. The coral colony will turn white because the algae provide the color to most hard corals. The polyps cannot live long without their zooxanthellae partners, placing the whole reef at risk.
Land-Based Sources of Pollution
Land-based sources of pollution like runoff, sediment, sewage, and nutrients threaten coral reefs. They can overwhelm corals, lowering their ability to filter pollutants. Smothering algae, disease, and low oxygen degrade and damage the reef.
Invasive Species
A healthy habitat is a balanced, interdependent system that can be toppled by non-native species. When new species with no local predators are introduced, they can take over, altering reef habitats by consuming light, oxygen, food, and other resources. When the reef is weakened or corals die, native species will decline and disappear.
Physical Impacts
Located close to the ocean’s surface, coral reefs are at risk for physical impacts caused by ship groundings, anchor damage, and storms. This can result in significant local losses of corals that are hundreds of years old.
Image
A diver attaches corals to the reef bottom. Credit: Reef Resilience Network.
What We Do
We Protect Coral Reefs
The best way to conserve coral reefs and reduce future habitat loss is to know everything we can about them. We address coral conservation priorities by locating, surveying, and
monitoring America’s coral reefs
in the Caribbean (Florida, Puerto Rico, U.S. Virgin Island) and the
Pacific
(American Samoa, Guam, Hawaii, Northern Marianas Islands).
As part of the
NOAA Coral Reef Conservation Program
, our
Coral Reef Information System
organizes data from all NOAA and partner actions, including:
Reef mapping
Monitoring and assessment
Biological and socioeconomic research and modeling
Outreach and education
Management and stewardship
We’ve studied how coral reefs enhance local economies, water quality, and fishery productivity. Monitoring reef health means we can respond quickly to mitigate invasive species and disease, as well as land-based sources of pollution, vessel groundings, and oil spills.
We Restore Coral Reefs
The
Office of Habitat Conservation
’s NOAA Restoration Center provides funding and
technical assistance
to habitat restoration projects across the country, including efforts to restore coral reefs. We work with the NOAA Coral Reef Conservation Program, the
Damage, Assessment, Remediation, and Restoration Program
, and other NOAA offices to
help threatened shallow coral species recover
In the Florida Keys National Marine Sanctuary, NOAA and partners are working to implement
Mission: Iconic Reefs
, a first-of-its-kind approach to restoring corals at seven ecologically and culturally significant reef sites. By the end of this effort, coral cover across the seven sites will be restored from 2 percent to an average of 25 percent.
We participate in a diverse set of other coral-related restoration activities across the Caribbean and Florida, as well as
in the Pacific
. Our work includes:
Facilitating, leading, funding, and implementing efforts to grow corals in protected conditions. NOAA and partners collect broken corals and grow them in dense coral nurseries. We then reattach the coral fragments to reefs piece by piece with cement, zip ties, and nails.
Combating invasive species, such as algae, that disturb the balance of life on reefs. To further prevent reefs from being smothered, we work to reduce runoff of sediment and other pollutants, which can feed algae growth, from nearby land.
Establishing a contract-based emergency response system to address ship groundings and other physical impacts to corals. This system has responded to hundreds of incidents, saving tens of thousands of corals.
We Partner to Support Coral Reef Habitat
To address the complex nature of threats that face shallow and deep sea corals, we work through the NOAA Coral Reef Conservation Program and with partners to protect these valuable habitats. Restoration funding provided by the program enables state and local organizations to conduct projects of value to their communities. For every million dollars in grants we award, 15 or more jobs are created in addition to the resource recovery value.
What You Can Do
Learn more about coral reefs.
Share your new knowledge!
Volunteer.
Get involved in community coral reef restoration, monitoring programs, aquariums, or beach cleanups. For example, the Southeast Florida Action Network uses community volunteers to
help report coral disease
Purchase wisely.
Buy ethically raised and legally collected aquarium fish and corals. Don't buy live corals, jewelry, or decorative items without knowing the source and sustainability of the coral.
Practice good coral reef etiquette.
Remember, you are visiting the animals’ home. Avoid touching or taking coral if you dive on a reef. Keep hands and fins off the reef, and avoid stirring up the bottom. These sediments can smother corals.
Boat safely.
If you go boating near a coral reef, don’t anchor on the reef. Use mooring buoy systems when available, and make sure sewage from your boat or RV is correctly handled.
Use mineral-based sunblock.
Avoid chemical-based sunscreens, which can be extremely
harmful to marine life
Eat sustainable seafood.
Visit our
seafood profiles
to find good choices.
Avoid chemically-enhanced pesticides and fertilizers.
Although you may live thousands of miles from a reef ecosystem, these products can flow downstream.
Conserve water.
The less water you use, the less runoff and wastewater eventually finds its way back into our oceans.
Reduce, reuse, recycle.
Don’t trash the sea. Report dumping or other illegal activities.
More Information
More Information
Restoring Coral Reefs
NOAA Coral Reef Conservation Program
National Coral Reef Monitoring Program
Office of Habitat Conservation
on 04/23/2026
Reef Fish
Corals