Hydrodynamic controls on carbonate mound development: long term in situ seabed BOBO-lander observations and CTD-casts at the SW Rockall Trough Margin and in the Gulf of Cadiz

Abstract

Long term records obtained by in situ seabed observatories and repeated CTD casts show the presence of a high energetic environment in and around two cold water coral mound provinces at the SW RT margin and in the Gulf of Cadiz. In both areas cold water corals are present on the mounds, but the areas differ strongly in geological setting, as well as in sedimentology and hydrography. Measurements of near bed hydrodynamics as recorded with freefalling seabed observatories and water column observations show that currents in mound areas have a major influence on the presence of living cold water corals and on the shape of carbonate mounds. While at the Southwest Rockall Trough margin a dense cover of live corals has been demonstrated, only isolated living colonies and coral debris covered with mud occur on the mounds in the Gulf of Cadiz, indicating that watermass properties and dynamics on the Southwest Rockall Trough are at the moment most favourable for coral growth.