Science Center Objects

Coral reefs are unique ecosystems of plants, animals, and their associated geological framework. Although they cover less than 0.5% of Earth's surface, coral reefs are home to an estimated 25% of all marine species. Of the total coral reef habitat in United States waters, about 75%, or more than 16,000 square kilometers (6,000 square miles), is located in the Pacific Ocean.

Sky view of the coastline of a mountainous island with a shallow coral reef that has lots of deep holes and channels.

The challenging and complex study environment of Molokaʻi’s (Hawaiʻi) fringing reef.

The CMHRP has developed long-term partnerships with Federal, state, territorial, and local agencies, research institutions, nongovernmental organizations (NGOs), and universities in the study of vulnerable coral reef ecosystems. CMHRP researchers contribute to these studies by collecting data on waves, sediment transport, physical ocean properties (e.g., temperature and salinity), water chemistry, reef geomorphology, and reef geologic structure to characterize the natural processes that are critical to the health and sustainability of Pacific coral reefs, as well as the human impacts on these fragile ecosystems. The CMHRP input permits researchers to strategically and efficiently target specific research gaps while local and regional collaborators focus on longer-term monitoring.

Computer illustration in relief, of a coral reef underwater, colored areas show various biological cover.

Three-dimensional perspective view, looking northwest, of the Pala'au region of the south Moloka'i reef (derived from satellite imagery, underwater video, and other data sources) showing major biological cover. Information such as this is used by partnering organizations to manage coral reef resources. From Cochran, 2008

Project-specific USGS reports, peer-reviewed journal articles, invited lectures, briefings, and outreach programs describe scientific results that are relevant to managers and stakeholders concerned with coral reef health. CMHRP studies of sediment impacts to reefs have provided guidance to foreign governments and international agencies. Tools and techniques developed by CMHRP coral reef scientists have assisted national monitoring efforts related to coral reefs; these data have played critical roles in governmental decisions to better protect and preserve U.S.-managed coral reefs on the islands of Oʻahu, Guam, Kahoʻolawe, and American Samoa and motivated NGO restoration actions on Molokaʻi and Kauaʻi. Similarly, data and findings from CMHRP coral reef hydrogeologic studies have played pivotal roles in legal rulings to better protect U.S.-managed coral reefs on the islands of Maui and Hawaiʻi. CMHRP high-resolution maps and studies of natural processes have contributed to our understanding of how human activities and climate change have affected coral reefs within U.S. National Parks and in U.S. Coral Reef Task Force Priority Study Areas in the Pacific Ocean.

Future CMHRP research will address not only the natural controls on coral reef ecosystems, but also how human activities and climate change impact them at local, regional, and global scales. Work will focus on:

  1. providing national assessments of the roles of coral reefs in mitigating the risks of coastal hazards and the threats to coral reef ecosystems,
  2. forecasting and hindcasting ecological change,
  3. understanding human influences in the context of natural variations, and
  4. further developing national and international partnerships.
Coral head that looks like lettuce sits on sandy bottom in clear blue water and is surrounded by brightly colored fish.

Cerulean damselfish dart around lettuce coral off the Cape Range National Park along the Ningaloo Coast in Western Australia. USGS researchers combined forces with Australian colleagues in this UNESCO World Heritage Site to study how erosion of reefs contribute sand to the beaches—a coast’s natural armor. Credit: Curt Storlazzi, USGS

coral reef

Photo of a healthy coral reef taken at Palmyra National Wildlife Refuge. Credit: Kevin Lafferty, USGS