Explore the fascinating undersea world of coral reefs. Learn how we map, monitor, and model coral reefs so we can better understand, protect, and preserve our Nation's reefs.
Coral reefs are unique ecosystems of plants, animals, and their associated geological framework. Coral reefs cover less than 0.5 percent of the earth's surface, but are home to an estimated 25 percent of all marine species. Second only to tropical rainforests in size and complexity, some scientists estimate that more than one million species of plants and animals are associated with coral reefs. Coral reefs are also of great economic importance to those who live on or visit islands in the Pacific and Atlantic Oceans. Reefs shelter and provide nursery grounds for many commercially and culturally important species of fish and invertebrates, they protect the islands' harbors, beaches, and shorelines from erosion and wave damage by storms, and they are vital to the marine tourism industry. These diverse ecosystems provide valuable goods and services worth about $4 billion each year to the U.S.’s coastal communities. Yet, as important as coral reefs are, these ecosystems are being threatened worldwide.
More than 8,500 square miles (22,000 square kilometers) of coral reef habitat is found in U.S. waters. Most of these coral reefs still appear to be relatively healthy, but some areas of dead and dying coral have been found in recent years. The causes of this degradation are poorly known, but are probably in part related to human activities.
The U.S. Geological Survey (USGS), working closely with academic institutions, state, and other Federal agencies, is spearheading an effort to better understand the geologic and oceanographic controls on the structure and processes of our Nation's coral reef ecosystems.
This web site is a gateway to USGS studies of coral reefs. We focus on the geophysical processes that influence the health and sustainability of coral reefs. From this work we are gaining new insight into the structure of coral reefs, providing the basis for future monitoring, and understanding better both the influences of natural processes and impacts of human activities on coral reef health. These efforts will help to preserve and protect the biodiversity, health, and social and economic value of these remarkable habitats.
Read more coral reef facts.
Learn about our current studies by topic.
Climate Change and Land-use Histories
We are developing new and unique oceanographic and environmental archives from coral skeleton records to better understand the compounding effects of land-use and environmental change on coral reef health.
We are conducting geophysical and geochemical research to address questions about coastal groundwater-to-reef flow and coral reef health, with the goal of informing management decisions related to planning and implementing activities in priority watershed-coral reef systems.
Reef Hydrodynamics and Sediment Processes
We are developing a better understanding how tides, waves, currents, and both land- and reef-derived sediment influence the development of coral reefs and their adjacent shorelines.
Role of Reefs in Coastal Protection
We are combining ocean, engineering, ecologic, social, and economic modeling to provide a high-resolution, rigorous, spatially-explicit valuation of the coastal flood protection benefits provided by coral reefs and the cost effectiveness of reef restoration for enhancing those benefits.
Reef Resource Assessments - Planning for the Future
We are mapping and assessing all of the important geologic and oceanographic factors to identify those coral reefs most at risk and those reefs that are potentially the most resilient and the most likely to recover from natural and human-driven impacts.
Also, learn about our studies by location:
- Guam
- Hawai‛i
- Kaho‛olawe
- Kaua‛i
- Kwajalein Island
- Lāna‛i
- Maui
- Moloka‛i
- O‛ahu
- Puerto Rico
- Roi-Namur Island
- Tutuila
Please also see the associated Coral Reef Ecosystem Studies (CREST) Project website.
Our partners are numerous and include:
- U.S. Coral Reef Task Force (USCRTF)
- Department of the Interior
- Other Federal Partners
- State Partners
- Territorial and Commonwealth Partners
- Guam Division of Aquatic and Wildlife Resources
- Commonwealth of the Northern Mariana Islands Department of Land and Natural Resources
- American Samoa Department of Marine and Wildlife Resources
- Puerto Rico Department of Natural and Environmental Resources
- U.S. Virgin Islands Department of Planning and Natural Resources
- Academia
- University of California Santa Cruz - Institute of Marine Sciences
- University of Western Australia - Oceans Institute
- University of Puerto Rico at Mayaguez - Center for Applied Ocean Science & Engineering
- University of Hawaiʻi - Hawaiʻi Institute of Marine Biology
- Woods Hole Oceanographic Institution - Department of Geology and Geophysics
- Delft University of Technology - Department of Hydraulic Engineering
- Queen's University - Department of Civil Engineering
- University of Cantabria - Department of Sciences and Techniques in Water and Environment
- Non-governmental Organizations
Below are data releases associated with this project.
Below are multimedia items associated with this project.
Below is a list of our project publications.
Numerical modeling of the impact of sea-level rise on fringing coral reef hydrodynamics and sediment transport
Seafloor morphology and coral habitat variability in a volcanic environment: Kaloko-Honokohau National Park, Hawaii, USA
The use (and misuse) of sediment traps in coral reef environments: Theory, observations, and suggested protocols
Coastal circulation and sediment dynamics in Maunalua Bay, Oahu, Hawaii: Measurements of waves, currents, temperature, salinity, and turbidity: November 2008-February 2009
Terrigenous sediment provenance from geochemical tracers, south Molokai reef flat, Hawaii
Submarine groundwater discharge and fate along the coast of Kaloko-Honokohau National Historical Park, Island of Hawai`i: Part 3, spatial and temporal patterns in nearshore waters and coastal groundwater plumes, December 2003-April 2006
Turbidity on the shallow reef off Kaulana and Hakioawa watersheds, north coast of Kaho'olawe, Hawai'i: Measurements of turbidity and ancillary data on winds, waves, precipitation, and stream flow discharge, November 2005 to June 2008
Predictions of turbidity due to enhanced sediment resuspension resulting from sea-level rise on a fringing Coral Reef: Evidence from Molokai, Hawaii
Coral Ba/Ca records of sediment input to the fringing reef of the southshore of Moloka'i, Hawai'i over the last several decades
Coral proxy record of decadal-scale reduction in base flow from Moloka'i, Hawaii
Coastal Circulation and Sediment Dynamics in War-in-the-Pacific National Historical Park, Guam; measurements of waves, currents, temperature, salinity, and turbidity, June 2007-January 2008
Science-Based Strategies for Sustaining Coral Ecosystems
Below are news stories associated with this project.
USGS Investigations of coral reefs are cooperative efforts, and our scientists are working in partnership and cooperation with the following organizations.
Explore the fascinating undersea world of coral reefs. Learn how we map, monitor, and model coral reefs so we can better understand, protect, and preserve our Nation's reefs.
Coral reefs are unique ecosystems of plants, animals, and their associated geological framework. Coral reefs cover less than 0.5 percent of the earth's surface, but are home to an estimated 25 percent of all marine species. Second only to tropical rainforests in size and complexity, some scientists estimate that more than one million species of plants and animals are associated with coral reefs. Coral reefs are also of great economic importance to those who live on or visit islands in the Pacific and Atlantic Oceans. Reefs shelter and provide nursery grounds for many commercially and culturally important species of fish and invertebrates, they protect the islands' harbors, beaches, and shorelines from erosion and wave damage by storms, and they are vital to the marine tourism industry. These diverse ecosystems provide valuable goods and services worth about $4 billion each year to the U.S.’s coastal communities. Yet, as important as coral reefs are, these ecosystems are being threatened worldwide.
More than 8,500 square miles (22,000 square kilometers) of coral reef habitat is found in U.S. waters. Most of these coral reefs still appear to be relatively healthy, but some areas of dead and dying coral have been found in recent years. The causes of this degradation are poorly known, but are probably in part related to human activities.
The U.S. Geological Survey (USGS), working closely with academic institutions, state, and other Federal agencies, is spearheading an effort to better understand the geologic and oceanographic controls on the structure and processes of our Nation's coral reef ecosystems.
This web site is a gateway to USGS studies of coral reefs. We focus on the geophysical processes that influence the health and sustainability of coral reefs. From this work we are gaining new insight into the structure of coral reefs, providing the basis for future monitoring, and understanding better both the influences of natural processes and impacts of human activities on coral reef health. These efforts will help to preserve and protect the biodiversity, health, and social and economic value of these remarkable habitats.
Read more coral reef facts.
Learn about our current studies by topic.
Climate Change and Land-use Histories
We are developing new and unique oceanographic and environmental archives from coral skeleton records to better understand the compounding effects of land-use and environmental change on coral reef health.
We are conducting geophysical and geochemical research to address questions about coastal groundwater-to-reef flow and coral reef health, with the goal of informing management decisions related to planning and implementing activities in priority watershed-coral reef systems.
Reef Hydrodynamics and Sediment Processes
We are developing a better understanding how tides, waves, currents, and both land- and reef-derived sediment influence the development of coral reefs and their adjacent shorelines.
Role of Reefs in Coastal Protection
We are combining ocean, engineering, ecologic, social, and economic modeling to provide a high-resolution, rigorous, spatially-explicit valuation of the coastal flood protection benefits provided by coral reefs and the cost effectiveness of reef restoration for enhancing those benefits.
Reef Resource Assessments - Planning for the Future
We are mapping and assessing all of the important geologic and oceanographic factors to identify those coral reefs most at risk and those reefs that are potentially the most resilient and the most likely to recover from natural and human-driven impacts.
Also, learn about our studies by location:
- Guam
- Hawai‛i
- Kaho‛olawe
- Kaua‛i
- Kwajalein Island
- Lāna‛i
- Maui
- Moloka‛i
- O‛ahu
- Puerto Rico
- Roi-Namur Island
- Tutuila
Please also see the associated Coral Reef Ecosystem Studies (CREST) Project website.
Our partners are numerous and include:
- U.S. Coral Reef Task Force (USCRTF)
- Department of the Interior
- Other Federal Partners
- State Partners
- Territorial and Commonwealth Partners
- Guam Division of Aquatic and Wildlife Resources
- Commonwealth of the Northern Mariana Islands Department of Land and Natural Resources
- American Samoa Department of Marine and Wildlife Resources
- Puerto Rico Department of Natural and Environmental Resources
- U.S. Virgin Islands Department of Planning and Natural Resources
- Academia
- University of California Santa Cruz - Institute of Marine Sciences
- University of Western Australia - Oceans Institute
- University of Puerto Rico at Mayaguez - Center for Applied Ocean Science & Engineering
- University of Hawaiʻi - Hawaiʻi Institute of Marine Biology
- Woods Hole Oceanographic Institution - Department of Geology and Geophysics
- Delft University of Technology - Department of Hydraulic Engineering
- Queen's University - Department of Civil Engineering
- University of Cantabria - Department of Sciences and Techniques in Water and Environment
- Non-governmental Organizations
Below are data releases associated with this project.
Below are multimedia items associated with this project.
Below is a list of our project publications.
Numerical modeling of the impact of sea-level rise on fringing coral reef hydrodynamics and sediment transport
Seafloor morphology and coral habitat variability in a volcanic environment: Kaloko-Honokohau National Park, Hawaii, USA
The use (and misuse) of sediment traps in coral reef environments: Theory, observations, and suggested protocols
Coastal circulation and sediment dynamics in Maunalua Bay, Oahu, Hawaii: Measurements of waves, currents, temperature, salinity, and turbidity: November 2008-February 2009
Terrigenous sediment provenance from geochemical tracers, south Molokai reef flat, Hawaii
Submarine groundwater discharge and fate along the coast of Kaloko-Honokohau National Historical Park, Island of Hawai`i: Part 3, spatial and temporal patterns in nearshore waters and coastal groundwater plumes, December 2003-April 2006
Turbidity on the shallow reef off Kaulana and Hakioawa watersheds, north coast of Kaho'olawe, Hawai'i: Measurements of turbidity and ancillary data on winds, waves, precipitation, and stream flow discharge, November 2005 to June 2008
Predictions of turbidity due to enhanced sediment resuspension resulting from sea-level rise on a fringing Coral Reef: Evidence from Molokai, Hawaii
Coral Ba/Ca records of sediment input to the fringing reef of the southshore of Moloka'i, Hawai'i over the last several decades
Coral proxy record of decadal-scale reduction in base flow from Moloka'i, Hawaii
Coastal Circulation and Sediment Dynamics in War-in-the-Pacific National Historical Park, Guam; measurements of waves, currents, temperature, salinity, and turbidity, June 2007-January 2008
Science-Based Strategies for Sustaining Coral Ecosystems
Below are news stories associated with this project.
USGS Investigations of coral reefs are cooperative efforts, and our scientists are working in partnership and cooperation with the following organizations.