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
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
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
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 searches for food.
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.
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 Hawaiis 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
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,
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,
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.
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.