60 - Cold-Water Coral Colonization of Alboran Sea Knolls, Western Mediterranean Sea

Abstract

The Alboran Sea is the westernmost basin of the Mediterranean Sea and represents a basin 350 km long and 150 km wide, with water depths between 0 and 2,000 m. The Alboran Sea is characterized by highly dynamic and variable water masses that make it one of the most productive areas in the oligotrophic Mediterranean Sea. Hydrodynamic features occur across all time and length scales, such as tidal motion, strong baroclinic jets, large-scale gyres, mesoscale eddies, upwelling regions, and frontal zones, all with important implications on the dynamics of plankton and benthic ecosystems [3]. The strong surface inflow of Atlantic water through the Strait of Gibraltar, known as the Atlantic Jet, maintains two semipermanent anticyclonic gyres consisting of a mixture of different proportions of Mediterranean and Atlantic waters that change in sympathy with tidal cycles. The knolls in the Alboran Sea are affected by benthic trawl fisheries, evidenced by trawl marks and lost fishing gear observed in the study area. Overall, the naturalness of the study area is considered to be modified. The topography of the Alboran Basin seafloor is characterized by pinnacles, knolls, banks, ridges, and troughs as a direct expression of the Pliocene-Quaternary compressive tectonic regime. Colonization in the past and present does not correspond to any particular side of the knoll flanks; hence, it appears there is no eznhanced source of nutrients nor any increased pressure related to sedimentation from any particular direction in the study area. Upscaling from detailed habitat maps of knolls to basin-wide predictive habitat maps reveals various potential CWC habitats that are not yet surveyed and might lead to new discoveries of relict and living CWC ecosystems in the basin.