Deep-sea Coral Ecology, Health, and Diversity
Project Status: This project began in January 2004 and is Ongoing
We conduct field surveys of the deep seafloor in the U.S. and neighboring waters to assess the distribution, health, and biodiversity of deep-sea coral ecosystems. We use remotely operated vehicles (ROVs) equipped with environmental sensors and high-resolution cameras to document and assess deep-sea coral habitats. The resulting information is used for better management and protection of these ecosystems and the associated species they support.
Why We Care
Deep-sea corals are fragile seafloor creatures living in cold, dark ocean waters from 50 to over 8,000 meters deep. They provide crucial habitat, refuge, and spawning grounds for fish, shrimp, crabs, and other important sea life. Sea fans and sponges found in these habitats hold potential for the development of important pharmaceuticals.
Deep-sea corals range in age from hundreds to thousands of years, and, because they are so slow growing, they are slow to recover from damage caused by destructive bottom fishing, oil and gas exploration, climate change, and land-based pollution.
What We Are Doing
We are surveying the deep seafloor (> 50 meters depth) to assess the health and condition of deep-sea coral habitats relative to environmental threats. The habitats and their stressors vary in character from region to region. The West Atlantic harbors large areas of deep-sea stony coral reefs in the midst of large energy reserves, but the North Pacific contains some of the most diverse and abundant communities in the midst of active bottom-fishing grounds.
We are working closely with NOAA National Marine Sanctuaries (NMS) to survey and document deep-sea habitats in protected and unprotected waters, particularly along the U.S. West Coast. We mapped seafloor habitat in the Gulf of Farallones NMS, we explored these newly mapped seafloor habitats using an ROV to assess deep-sea coral and sponge aggregations. We also explored deep-corals in and around Channel Islands NMS, investigating the vulnerability of these ecosystems to climate change and commercial fishing.
In the Gulf of Mexico, we are working on the Natural Resource Damage Assessment for Deepwater Horizon (NRDA-DWH), examining potential effects of the surface oil on mesophotic sea fans located below the surface slick. We are also helping NOAA's Deep-Sea Coral Research and Technology Program to develop a national database of known deep-sea coral locations throughout the region to improve habitat suitability modeling efforts.
What We Found in U.S. West Coast National Marine Sanctuaries
At Gulf of Farallones National Marine Sanctuary, our surveys resulted in:
- First high-resolution multibeam maps of the submerged continental shelf and slope between 50–1,000 meters depth (Dartnell et al. 2014)
- Detailed characterization of sponge, coral, and fish assemblages on Rittenburg Bank and the Farallon Escarpment (Etnoyer et al 2014), including
First documentation of habitat-forming deep-sea black coral Antipathes dendrochristos north of Point Conception,
First documentation of the deep-sea bubblegum coral Paragorgia stephencairnsii in Gulf of Farallones NMS, and
Evidence of deep-sea corals and sponges providing essential fish habitat for yelloweye rockfish, among other species.
At Olympic Coast National Marine Sanctuary, our surveys resulted in:
- The first-ever records of the habitat-forming stony coral Lophelia pertusa (Hyland et al. 2008),
- Photographic evidence that deep-sea gorgonian corals serve as habitat for commercially important rockfishes (Brancato et al. 2010),
- Photographic evidence of human influence on the seafloor, including trawl marks in sediment, overturned rocks, lost fishing gear, and dead coral entangled in lost gear (Brancato et al. 2010),
- More than 2,000 records of octocorals and black corals added to NOAA’s National Database of Deep-Sea Corals,
- Our data played a key role in planning for the Olympic 2 Groundfish Essential Fish Habitat (EFH) Conservation Area, established in June 2006, and
- Our data played a key role in marine spatial planning, such as the establishment of deep-sea coral marine sanctuaries that provide protection from bottom-fishing and other human uses.
What We Found in U.S. Neighboring Seas
In the Caribbean Sea, our surveys resulted in:
- First reports of deep-sea coral Lophelia pertusa off Roatan, Honduras (Etnoyer et al 2011),
- First visual surveys and exploration deeper than 300 m, first records of Madrepora and Paracalyptrophora off Belize, and
- First publicly available high-resolution multibeam maps of the southern Mesoamerican Reef continental slope between 50–3,000 meters depth off Honduras and Belize.
Our future plans include:
New benthic surveys using ROVs in the Gulf of Alaska, Southern California Bight, and the Gulf of Mexico
Exploration of the influence of ocean acidification and climate change on deep-sea corals in Southern California
Ongoing studies of health and condition of sea fans on mesophotic reefs in the Northwest Gulf of Mexico as part of the Natural Resource Damage Assessment for Mississippi Canyon 252
Related Regions of Study: Gulf of Mexico, Alaska, California, Washington
Primary Contacts: Peter Etnoyer, Jeff Hyland
Science for Coastal Ecosystem Management (Marine Spatial Planning, Protected Species, Coral)
Related NCCOS Center: CCEHBR