Deep-water coral development as a function of hydrodynamics and surface productivity around the submarine banks of the Rockall Trough, NE Atlantic

Abstract

The dynamics that occur at the Porcupine Bank, Rockall Trough, are described in relation to the role the bank, and others like it, may play in the development of deep-water corals, such as Lophelia pertusa (L.), which occurs widely in the NE Atlantic. High productivity has been measured over the bank, and it appears that this productivity may be fuelled by an increase in nutrients available over the bank through winter convection which leaves dense, nutrient rich water on the bank. This dense water drains away slowly through the benthic boundary layer (BBL) providing a mechanism for downslope transport of organic material in the boundary layer. Processes such as rectification of diurnal tides and Taylor column formation generate closed circulation patterns around the bank and promote the retention of organic matter over the bank. Similar processes have been observed over other Rockall Trough banks, and the combination of these processes appear to promote the availability of food to the corals that inhabit the lower flanks of the banks, particularly on the coral-dominated carbonate mounds that also occur there.