SEAFLOOR COVERAGE AND BENTHIC LANDSCAPES ASSOCIATED TO DIAPIRIC (MUD VOLCANISM) FORMATIONS IN SALMEDINA BANKS, COLOMBIAN CARIBBEAN CONTINENTAL SHELF

Abstract

The submarine ecological units around an active mud volcano in the offshore banks of Salmedina, Colombian Caribbean, were determined and mapped employing geo-referenced submarine video-transects, bathymetry analysis, and interpretation of satellite imagery. Distribution, relative cover, and the most representative benthic, sessile organisms of the different ecological units are described. In the shallow zone of the banks, 60 % of the substrate was covered by algae and only 10 % by living corals. The relative cover of living corals in deeper zones increased to 33 % in semi vertical slopes and up to 55 % on the upper flats of deeper located banks. The dominant coral species overall were Siderastrea siderea and Montastraea annularis. A determining natural factor in the reef structure in the zone seems to be recent diapiric activity, with a constant mud emanation in the western sector. The Banks of Salmedina are under the influence of turbid plumes that seemingly increase sedimentation and are impacted by blast fishing as well. Although the shallowest zone of the bank shows the highest affectation, the coral community in the deeper zones still exhibit a noticeable cover of living coral, even higher than in other areas in the region with similar features. The recent diapiric activity of constant mud ejection determines the coral community structure in the western sector.