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Deep-Sea Corals—Habitat of the Month

What are Deep-Sea Corals?

Most people associate corals with snorkeling around sunlit reefs in the tropics. But these shallow water corals have deep-sea cousins all over the globe. As their name suggests, deep-sea corals live in cold oceanic waters. They thrive on continental shelves, canyons, and seamounts, especially between 200 and 6,000 feet deep. They receive little to no light, and survive by trapping microscopic organisms as they pass in the currents. Deep-sea corals are extremely slow-growing, but can survive for thousands of years. In fact, some black corals have recently been estimated to be more than 4,200 years old—making them the oldest known living marine organisms.

With more than 3,000 species and every variation of shape and color imaginable, the world of deep-sea corals has already proven to be incredibly diverse.

Underwater Forests

Deep-sea corals can form reefs that stretch for miles.  Some species grow as bush- or tree-like colonies that can form veritable forests on the otherwise relatively barren sea floor. These deep-sea corals provide habitat for an array of species. Starfish, lobster, and hundreds of other invertebrates call these corals home, and fish like grouper, rockfish and snapper use them to hide from predators.

Some deep-sea corals and sponges have been found to contain medically valuable compounds that exhibit anti-inflammatory, anti-viral and anti-tumor properties. Since deep-sea coral research is still only a few decades old, it is impossible to say how many more such discoveries might be found.

Threats from Above

You would think that at such great depths deep-sea corals would be safe from harmful interactions with humans—but that’s not the case. Fishing boats are traveling further out to sea, using more efficient bottom trawl gear that rakes over and breaks corals on the sea floor. Because deep-sea corals grow so slowly, it can take hundreds of years for them to rebuild, if they rebuild at all.

Due to the technical and financial challenges to studying ecosystems in extreme environments like the deep ocean, scientists still know relatively little about how deep-sea coral ecosystems function and what their loss might mean for the ocean environment, humans, and the planet. It could spell the loss of valuable seafood species and as-yet-undiscovered, life-saving pharmaceutical compounds. Beyond that, the extent of what we could lose is a great unknown.

Diving Deeper

NOAA was an early leader in exploring deep-sea habitats. In 2009, we established the Deep Sea Coral Research and Technology Program to increase scientific understanding of deep-sea coral ecosystems. Through major regional field research initiatives and a variety of deep-sea coral research projects around the nation, the program provides ocean resource managers with scientific studies to inform conservation actions.

NOAA, in partnership with the eight Regional Fishery Management Councils, has also been leading the way in protecting deep-sea corals from the impacts of fishing operations. Since 2006, NOAA has protected more than half a million square miles of vulnerable deep-sea habitats from bottom-trawling.

Posted on 02/21/2012