Distribution, abundance and size of <i>Lophelia pertusa</i> coral reefs in mid-Norway in relation to seabed characteristics

Abstract

This paper presents results on the distribution, abundance, and size of Lophelia pertusa coral reefs in mid-Norway (62°30&amp;;–65°30&amp;;N) as compiled from own investigations, earlier scientific reports, reports from fishery surveys and fishermen. Detailed bathymetrical mapping covering an area of ∼600 km 2 along the Halten gas-pipeline, and two nearby areas across the shelf revealed 70 Lophelia reefs. In general, the reefs occurred close to breaks and escarpments. High densities of up to nine reefs per km 2 were found in areas with a rugged seabed topography and with a slope &gt;0·6°. These seabed features have probably positive influence on the transport and concentration of food particles and thus control the local distribution of Lophelia . The area covered by individual reefs varied between 1230 m 2 and 37,310 m 2 with a mean of 5628 m 2 . The height of the reefs was positively correlated with the area. Reefs &lt;10,000 m 2 had a circular outline, while larger reefs were elongate, aligned parallel to the depth contours. Along the pipeline the average density of Lophelia reefs was 0·09 km −2 which indicates that the total number of reefs is ∼6300, covering ∼35 km 2 within the whole study area.