The Atlantic-Mediterranean ecological connection: A study on decapod larval communities

Abstract

Larval dispersal mechanisms, although significantly studied, are far from being completely resolved. Local studies are needed to clarify key interactions between individual life cycles and transport processes. The Atlantic-Mediterranean connection through the Strait of Gibraltar is a particularly important area to explore these processes, as a biodiversity hotspot for detecting species fluxes and/or invasions between several Large Marine Ecosystems. However, both the area dynamics and the mechanisms used by the larvae to cope with the system hydrological conditions are scantly explored. Summer data on decapod larvae and ocean water masses from an extended area of southern Portugal, Gulf of Cadiz, Strait of Gibraltar and Alboran Sea were analysed, and the larval assemblages and their potential retention/dispersal mechanisms were explored. Different larval assemblages were linked to the hydrological conditions of each basin. Shelf width differences and its influence in along/cross-shore transport were the main drivers of decapod distribution, acting as biological barriers. Larvae of mesopelagic species dominated the northern Alboran Sea inner-shelf, highly influenced by offshore currents. Here, the nearshore processes were limited to surface waters, while in the Gulf they extended more deeply and onto the outer shelf. Results on species ecological traits can be applied to similar oceanographical world coastal areas and could be used for further development of ecological modelling studies.