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NURP Research Supports Conservation of Deep-Sea Corals

Delicate pink parasol coral (Metallogorgia sp.) extends into the water column

Delicate pink parasol coral (Metallogorgia sp.) extends into the water column.

The term 'coral' evokes images of shallow sunlit reefs with a wide diversity of associated organisms, including an abundance of colorful fishes. Most people are aware of the role that coral reefs play in supporting the local economies of tourist destinations like the Florida Keys and the Hawaiian Islands. Further, most are aware of the dangers that increasing water temperatures, overfishing, and disease on the ecological health of reef ecosystems. However, most people, except fishermen and some scientists, are unaware that corals also occur in cold water and deep-sea regions around the earth.

Although the existence of deep-sea corals was first documented about two and a half centuries ago, most of what we know about them has come from exploration and research within the past few decades. With the development of simple underwater imaging technologies like camera sleds, and more complex vehicles like occupied submersibles and remotely operated vehicles, scientists have been able to begin the study of corals and associated organisms within their natural environments.

What Are Deep-Sea Corals?
Deep-sea corals are members of the Class of animals called Anthozoa, which among other creatures, includes sea anemones, stony corals, soft corals and sea pens. Deep-sea corals inhabit the colder deep waters of our continental shelves, submarine canyons, seamounts, mid-ocean ridges and other habitats within the ocean abyss to depths deeper than 6000 m. Where current and substrate conditions are suitable, these corals can form complex reefs, thickets or groves of high complexity, depending on species. Similar to the ancient redwood and sequoia trees, these animals are slow growing and can reach hundreds of years to over a millennia in age, they provide habitat for many other organisms (including species of economic importance), and their skeletons provide important historical records of climate change.

Ecology of Deep-Sea Coral
Like ancient forests, corals provide habitat for a diversity of other organisms. Unlike the terrestrial forests, however, little is known about their distribution, ecological role, and conservation status. In fact, recent evidence suggests that fishing has had substantial impacts on these communities in both the North Atlantic and Pacific Oceans. This combined with their slow growth rate and potential role as habitat for a number of commercially and ecologically important species could produce long lasting effects on deep-sea communities. We must understand the distribution, fundamental life history, repbroduction and ecological role of these organisms in order to manage and conserve these forests of the deep.

Polyps extended from deep-sea coral colony

Polyps extended from deep-sea coral colony.

Coral Systematics
Imagine collecting a net full of fish and not being able to name them by species. How would it be possible to map their distribution, understand their ecological role, or understand if they are common or rare? One of the fundamental problems in working with deep-sea corals is identifying who all of the species are and how they are distributed. While some species are quite common across ocean basins, finding new species (or sub-species) and range extensions is not uncommon. There is much to learn about the how the diversity of coral species are distributed in the deep sea waters of the world.

Population Genetics
How are populations of corals connected? Are coral populations spread across the undersea landscape along a series of stepping-stones or do they send larvae everywhere and patchy populations are the result of random recruitment? Modern molecular techniques that can track markers in the genes of corals can be used to understand how populations are connected and can lead to understanding of how best to conserve these long-lived animals.

Population Age Structure, Reproduction and Recruitment
How old are coral colonies? When do corals spawn? What environmental changes trigger reproduction? How many new recruits survive to reproductive age? These are critical questions for understanding how coral population's change and how resilient they are to natural and human caused disturbances.

grenadier hovers over rock substrate in search of food

Grenadier searches for food.

Functional Role
What role do corals play in mediating the distribution and abundance of mobile organisms like crustaceans and fishes? Do corals enhance local patterns of biological diversity? Do corals provide sites for fish spawning? Do corals enhance feeding opportunities for fish by concentrating prey items like shrimp? Do corals provide shelter from predators? These questions and many others get at the issue of the functional role of corals in deep-sea ecosystems. Understanding the functional role of corals allows us to understand both the fundamental way in which these mysterious communities of organisms operate and how we might conserve and sustainably use these components of biological diversity.

NURP Projects
Studies of deep-sea corals are difficult to accomplish without the fine-scale maneuverability of undersea vehicles. Using occupied submersibles and remotely operated vehicles, research has been conducted in highly complex environments where corals occur at high densities. Current research has only begun to clarify our understanding of the ecology of corals and their functional role. Below are a few examples of recent NURP projects focused on this new and exciting area of research:

Baco-Taylor, A., T. M. Shank, and T. C. Shirley. Deep Sea Precious Corals as Habitat for Macroinvertebrates in Hawaii. (Operations year: 2005)

David, A. W.. Mapping the Oculina Banks Marine Protected Area. (Operations year: 2005)

Grigg, R. W., and S. E. Kahng. The Ecological Impact of an Alien Marine Invertebrate on Hawai‘i’s Deep Water Coral Reef Community. (Operations year: 2005)

Miller, M. W., and A. N. Shepard. Effectiveness of the Oculina OHAPC: monitoring coral health and use by groupers. (Operations year: 2005)

Shepard, A.N. and J.K. Reed. Mapping and Characterization of the Oculina Habitat Areas of Particular Concern (OHAPC) off the East Coast of Florida. (Operations year: 2002, 2003)

Stone, R., J. Heifetz, D.A. Woodby and J.R. Reynolds. Distribution of deep-sea corals and associated communities in the Aleutian Islands. (Operations year: 2004)

Watling, L. E., P. J. Auster, and K. J. Eckelbarger. The Ecology of Deep Water Octocorals off the Northeast Coast of the United States (Operations years: 2002, 2003, 2004)

NURP Publications

McDonough, J.J. and K.A. Puglise. 2003. Summary: Deep-Sea Corals Workshop. International Planning and Collaboration Workshop for the Gulf of Mexico and the North Atlantic Ocean. Galway, Ireland, January 16-17, 2003. U.S. Dep. Commerce, NOAA Tech. Memo. NMFS-F/SPO-60, 51 p.

This document summarizes the proceedings of the Deep-Sea Corals Workshop held in Galway, Ireland on January 16-17, 2003. The workshop was hosted by the Irish Marine Institute and organized by the U.S. National Oceanic and Atmospheric Administration (NOAA) Fisheries (Office of Science and Technology) and Research (NOAA's Undersea Research Program and Office of Ocean Exploration).

Puglise, K.A., R.J. Brock, and J.J. McDonough III. 2005. Identifying critical information needs and developing institutional partnerships to further the understanding of Atlantic deep-sea coral ecosystems. In: A. Freiwald and J.M. Roberts (eds.). Cold-water Corals and Ecosystems. Springer-Verlag: Berlin Heidelberg. pp. 1129-1140.


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Updated: February 6, 2009