New view of the Belgica Mounds, Porcupine Seabight, NE Atlantic: preliminary results from the Polarstern ARK-XIX/3a ROV cruise

The Belgica Mound province is one of three provinces where carbonate mounds are associated with cold-water coral species in Porcupine Seabight, west of Ireland. Building upon extensive existing datasets, the Polarstern ARK XIX/3a cruise, deploying the robotic submersible VICTOR6000 (ROV), was undertaken in June 2003. This paper presents an overview of preliminary results from a reconnaissance video survey over and between several steep-flanked Belgica Mounds (giant mounds) and from a microbathymetric survey over some smaller mounds (Moira Mounds). Visual evidence for a strong hydrodynamic regime in the vicinity of the carbonate mounds is found with the interaction between currents and sedimentation having an important role in mound growth and development. Only some mounds show a high percentage of live coral coverage although there is a clear increase of megafaunal concentrations and species on mounds. One area of the province (the eastern ridge of aligned mounds) revealed very little live coral cover, asymmetrical drift accumulations burying the eastern sides and sediment-clogged dead coral frameworks at the western sides. This is in contrast to other areas (e.g., the western alignment of mounds) that show abundant live coral cover at present. In nearly all parts of the survey area the impact of fisheries, especially demersal trawling, is noted.