First observations of the cold-water coral Lophelia pertusa in mid-Atlantic canyons of the USA

Abstract

The structure-forming, cold-water coral Lophelia pertusa is widely distributed throughout the North Atlantic Ocean and also occurs in the South Atlantic, North Pacific and Indian oceans. This species has formed extensive reefs, chiefly in deep water, along the continental margins of Europe and the United States, particularly off the southeastern U.S. coastline and in the Gulf of Mexico. There were, however, no records of L. pertusa between the continental slope off Cape Lookout, North Carolina (NC) (∼34°N, 76°W), and the rocky Lydonia and Oceanographer canyons off Cape Cod, Massachusetts (MA) (∼40°N, 68°W). During a research cruise in September 2012, L. pertusa colonies were observed on steep walls in both Baltimore and Norfolk canyons. These colonies were all approximately 2m or less in diameter, usually hemispherical in shape and consisted entirely of live polyps. The colonies were found between 381m and 434m with environmental observations of: temperature 6.4–8.6°C; salinity 35.0–35.6; and dissolved oxygen 2.06–4.41mlL−1, all of which fall within the range of known L. pertusa distributions. All colonies were observed on vertical walls or underneath overhangs in areas of high current, which differs from observations further south, where L. pertusa colonizes rocky ledges and outcroppings, often forming large bioherms. We discuss observations from Baltimore and Norfolk canyons in the context of the known distribution of this species in the North Atlantic.