The Value of Our Reefs
Cost-benefit study confirms coral reef restoration could be a cost-effective way to save lives and money
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:
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.
Learn about our studies by location:
Guam
Hawaiʻi
Kahoʻolawe
Kauaʻi
Kwajalein Island
Lānaʻi
Maui
Molokaʻi
Oʻahu
Puerto Rico
Roi-Namur Island
Tutuila
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
Learn more about our related studies, and read basic facts about corals and reefs.
Quantifying Flood Risk and Reef Risk Reduction Benefits in Florida and Puerto Rico: The Consequences of Hurricane Damage, Long-term Degradation, and Restoration Opportunities
The Value of U.S. Coral Reefs for Risk Reduction The Value of U.S. Coral Reefs for Risk Reduction
Land-use Histories
Coral Reef Project: Kauaʻi
Coral Reef Project: Puerto Rico
Coral Reef Project: Oʻahu
Coral Reef Project: Tutuila
Coral Reef Project: Lānaʻi
Coral Reef Project: Kahoʻolawe
Coral Reef Project: Hawaiʻi
Coral Reef Project: Guam
Coral Reef Ecosystem Studies (CREST)
Below are data releases associated with this project.
Overlapping seabed images and location data acquired using the SQUID-5 system at Looe Key, Florida, in July 2021, with structure-from-motion derived point cloud, digital elevation model and orthomosaic of submerged topography Overlapping seabed images and location data acquired using the SQUID-5 system at Looe Key, Florida, in July 2021, with structure-from-motion derived point cloud, digital elevation model and orthomosaic of submerged topography
Model parameter input files to compare the influence of channels in fringing coral reefs on alongshore variations in wave-driven runup along the shoreline Model parameter input files to compare the influence of channels in fringing coral reefs on alongshore variations in wave-driven runup along the shoreline
Overlapping seabed images and location data acquired using the SQUID-5 system at Eastern Dry Rocks coral reef, Florida, in May 2021, with derived point cloud, digital elevation model and orthomosaic of submerged topography Overlapping seabed images and location data acquired using the SQUID-5 system at Eastern Dry Rocks coral reef, Florida, in May 2021, with derived point cloud, digital elevation model and orthomosaic of submerged topography
Aerial imagery and structure-from-motion-derived shallow water bathymetry from a UAS survey of the coral reef off Waiakane, Molokai, Hawaii, June 2018 Aerial imagery and structure-from-motion-derived shallow water bathymetry from a UAS survey of the coral reef off Waiakane, Molokai, Hawaii, June 2018
Flooding extent polygons for modelled wave-driven water levels in Florida with and without projected coral reef degradation Flooding extent polygons for modelled wave-driven water levels in Florida with and without projected coral reef degradation
Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida and the Commonwealth of Puerto Rico before and after Hurricanes Irma and Maria due to the storms' damage to the coral reefs Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida and the Commonwealth of Puerto Rico before and after Hurricanes Irma and Maria due to the storms' damage to the coral reefs
Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida, the Commonwealth of Puerto Rico, and the Territory of the U.S. Virgin Islands for current and potentially restored coral reefs Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida, the Commonwealth of Puerto Rico, and the Territory of the U.S. Virgin Islands for current and potentially restored coral reefs
Geochemistry time series and growth parameters from Tutuila, American Samoa coral record (ver. 2.0, June 2021) Geochemistry time series and growth parameters from Tutuila, American Samoa coral record (ver. 2.0, June 2021)
Coral geochemistry time series from Kahekili, west Maui Coral geochemistry time series from Kahekili, west Maui
Near-shore seawater-column measurements of excess radon (Rn-222) and water levels, Faga'alu Bay, Tutuila, American Samoa, August 2018 Near-shore seawater-column measurements of excess radon (Rn-222) and water levels, Faga'alu Bay, Tutuila, American Samoa, August 2018
Model parameter input files to compare locations of coral reef restoration on different reef profiles to reduce coastal flooding Model parameter input files to compare locations of coral reef restoration on different reef profiles to reduce coastal flooding
Cross-reef wave and water level data from coral reef environments (ver. 4.0, June 2025) Cross-reef wave and water level data from coral reef environments (ver. 4.0, June 2025)
Below are multimedia items associated with this project.
Below is a list of our project publications.
The potential for coral reef restoration to mitigate coastal flooding as sea levels rise The potential for coral reef restoration to mitigate coastal flooding as sea levels rise
Carbonate sediment transport across coral reefs: A comparison of fringing vs. barrier reefs Carbonate sediment transport across coral reefs: A comparison of fringing vs. barrier reefs
Modeling fluvial sediment plumes: Impacts to coral reefs Modeling fluvial sediment plumes: Impacts to coral reefs
Wave-scale observations of sediment resuspension and subsequent transport across a fringing reef flat Wave-scale observations of sediment resuspension and subsequent transport across a fringing reef flat
Observations of coastal circulation, waves, and sediment transport along West Maui, Hawaiʻi (November 2017– March 2018), and modeling effects of potential watershed restoration on decreasing sediment loads to adjacent coral reefs Observations of coastal circulation, waves, and sediment transport along West Maui, Hawaiʻi (November 2017– March 2018), and modeling effects of potential watershed restoration on decreasing sediment loads to adjacent coral reefs
Physicochemical coastal groundwater dynamics between Kauhakō Crater lake and Kalaupapa settlement, Moloka‘i, Hawai‘i Physicochemical coastal groundwater dynamics between Kauhakō Crater lake and Kalaupapa settlement, Moloka‘i, Hawai‘i
Coral reef restoration for risk reduction (CR4): A guide to project design and proposal development Coral reef restoration for risk reduction (CR4): A guide to project design and proposal development
Pharmaceuticals and personal care products in passive samplers at seven coastal sites off West Maui, Hawaiʻi: Pharmaceuticals and personal care products in passive samplers at seven coastal sites off West Maui, Hawaiʻi:
A numerical study of geomorphic and oceanographic controls on wave-driven runup on fringing reefs with shore-normal channels A numerical study of geomorphic and oceanographic controls on wave-driven runup on fringing reefs with shore-normal channels
The role of pH up-regulation in response to nutrient-enriched, low-pH groundwater discharge The role of pH up-regulation in response to nutrient-enriched, low-pH groundwater discharge
High-resolution observations of submarine groundwater discharge reveal the fine spatial and temporal scales of nutrient exposure on a coral reef: Faga'alu, AS High-resolution observations of submarine groundwater discharge reveal the fine spatial and temporal scales of nutrient exposure on a coral reef: Faga'alu, AS
Human and ecosystem health in coastal systems Human and ecosystem health in coastal systems
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:
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.
Learn about our studies by location:
Guam
Hawaiʻi
Kahoʻolawe
Kauaʻi
Kwajalein Island
Lānaʻi
Maui
Molokaʻi
Oʻahu
Puerto Rico
Roi-Namur Island
Tutuila
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
Learn more about our related studies, and read basic facts about corals and reefs.
Quantifying Flood Risk and Reef Risk Reduction Benefits in Florida and Puerto Rico: The Consequences of Hurricane Damage, Long-term Degradation, and Restoration Opportunities
The Value of U.S. Coral Reefs for Risk Reduction The Value of U.S. Coral Reefs for Risk Reduction
Land-use Histories
Coral Reef Project: Kauaʻi
Coral Reef Project: Puerto Rico
Coral Reef Project: Oʻahu
Coral Reef Project: Tutuila
Coral Reef Project: Lānaʻi
Coral Reef Project: Kahoʻolawe
Coral Reef Project: Hawaiʻi
Coral Reef Project: Guam
Coral Reef Ecosystem Studies (CREST)
Below are data releases associated with this project.
Overlapping seabed images and location data acquired using the SQUID-5 system at Looe Key, Florida, in July 2021, with structure-from-motion derived point cloud, digital elevation model and orthomosaic of submerged topography Overlapping seabed images and location data acquired using the SQUID-5 system at Looe Key, Florida, in July 2021, with structure-from-motion derived point cloud, digital elevation model and orthomosaic of submerged topography
Model parameter input files to compare the influence of channels in fringing coral reefs on alongshore variations in wave-driven runup along the shoreline Model parameter input files to compare the influence of channels in fringing coral reefs on alongshore variations in wave-driven runup along the shoreline
Overlapping seabed images and location data acquired using the SQUID-5 system at Eastern Dry Rocks coral reef, Florida, in May 2021, with derived point cloud, digital elevation model and orthomosaic of submerged topography Overlapping seabed images and location data acquired using the SQUID-5 system at Eastern Dry Rocks coral reef, Florida, in May 2021, with derived point cloud, digital elevation model and orthomosaic of submerged topography
Aerial imagery and structure-from-motion-derived shallow water bathymetry from a UAS survey of the coral reef off Waiakane, Molokai, Hawaii, June 2018 Aerial imagery and structure-from-motion-derived shallow water bathymetry from a UAS survey of the coral reef off Waiakane, Molokai, Hawaii, June 2018
Flooding extent polygons for modelled wave-driven water levels in Florida with and without projected coral reef degradation Flooding extent polygons for modelled wave-driven water levels in Florida with and without projected coral reef degradation
Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida and the Commonwealth of Puerto Rico before and after Hurricanes Irma and Maria due to the storms' damage to the coral reefs Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida and the Commonwealth of Puerto Rico before and after Hurricanes Irma and Maria due to the storms' damage to the coral reefs
Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida, the Commonwealth of Puerto Rico, and the Territory of the U.S. Virgin Islands for current and potentially restored coral reefs Projected flooding extents and depths based on 10-, 50-, 100-, and 500-year wave-energy return periods for the State of Florida, the Commonwealth of Puerto Rico, and the Territory of the U.S. Virgin Islands for current and potentially restored coral reefs
Geochemistry time series and growth parameters from Tutuila, American Samoa coral record (ver. 2.0, June 2021) Geochemistry time series and growth parameters from Tutuila, American Samoa coral record (ver. 2.0, June 2021)
Coral geochemistry time series from Kahekili, west Maui Coral geochemistry time series from Kahekili, west Maui
Near-shore seawater-column measurements of excess radon (Rn-222) and water levels, Faga'alu Bay, Tutuila, American Samoa, August 2018 Near-shore seawater-column measurements of excess radon (Rn-222) and water levels, Faga'alu Bay, Tutuila, American Samoa, August 2018
Model parameter input files to compare locations of coral reef restoration on different reef profiles to reduce coastal flooding Model parameter input files to compare locations of coral reef restoration on different reef profiles to reduce coastal flooding
Cross-reef wave and water level data from coral reef environments (ver. 4.0, June 2025) Cross-reef wave and water level data from coral reef environments (ver. 4.0, June 2025)
Below are multimedia items associated with this project.
Below is a list of our project publications.
The potential for coral reef restoration to mitigate coastal flooding as sea levels rise The potential for coral reef restoration to mitigate coastal flooding as sea levels rise
Carbonate sediment transport across coral reefs: A comparison of fringing vs. barrier reefs Carbonate sediment transport across coral reefs: A comparison of fringing vs. barrier reefs
Modeling fluvial sediment plumes: Impacts to coral reefs Modeling fluvial sediment plumes: Impacts to coral reefs
Wave-scale observations of sediment resuspension and subsequent transport across a fringing reef flat Wave-scale observations of sediment resuspension and subsequent transport across a fringing reef flat
Observations of coastal circulation, waves, and sediment transport along West Maui, Hawaiʻi (November 2017– March 2018), and modeling effects of potential watershed restoration on decreasing sediment loads to adjacent coral reefs Observations of coastal circulation, waves, and sediment transport along West Maui, Hawaiʻi (November 2017– March 2018), and modeling effects of potential watershed restoration on decreasing sediment loads to adjacent coral reefs
Physicochemical coastal groundwater dynamics between Kauhakō Crater lake and Kalaupapa settlement, Moloka‘i, Hawai‘i Physicochemical coastal groundwater dynamics between Kauhakō Crater lake and Kalaupapa settlement, Moloka‘i, Hawai‘i
Coral reef restoration for risk reduction (CR4): A guide to project design and proposal development Coral reef restoration for risk reduction (CR4): A guide to project design and proposal development
Pharmaceuticals and personal care products in passive samplers at seven coastal sites off West Maui, Hawaiʻi: Pharmaceuticals and personal care products in passive samplers at seven coastal sites off West Maui, Hawaiʻi:
A numerical study of geomorphic and oceanographic controls on wave-driven runup on fringing reefs with shore-normal channels A numerical study of geomorphic and oceanographic controls on wave-driven runup on fringing reefs with shore-normal channels
The role of pH up-regulation in response to nutrient-enriched, low-pH groundwater discharge The role of pH up-regulation in response to nutrient-enriched, low-pH groundwater discharge
High-resolution observations of submarine groundwater discharge reveal the fine spatial and temporal scales of nutrient exposure on a coral reef: Faga'alu, AS High-resolution observations of submarine groundwater discharge reveal the fine spatial and temporal scales of nutrient exposure on a coral reef: Faga'alu, AS
Human and ecosystem health in coastal systems Human and ecosystem health in coastal systems
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.