DIVERSITY AND BATHYMETRIC DISTRIBUTION OF DECAPOD CRUSTACEANS ATTRACTED TO BAITED TRAPS FROM THE MIDDLE SLOPE OF THE NORTHERN AEGEAN SEA

Abstract

We sampled the decapod crustaceans inhabiting the depth zone between 500 and 1500 m off Gokceada Island (northern Aegean Sea) from May 2010 to November 2011. The deep-slope decapod fauna of the northern Aegean Sea was sampled with baited traps. A total of 23 species of decapods have been identified at 32 stations. The results were analysed in terms of composition and distribution of benthic and benthopelagic bait-attracted species between regions. In addition, they were compared between stations in relation to the depth gradient. The results are discussed in relation to previous studies carried out in the eastern and western Mediterranean. Also, the use of traps is commented for different regions and the effects of the sampler on benthic species are discussed. The most common species was the penaeid shrimp, Parapenaeus longirostris in samples taken between 500 and 600 m. It is followed by Polycheles typhlops and the pandalid shrimp Plesionika martia martia. These species constitute more than 50% of all decapods. Differences among the strata at 500-1500 m depth were tentatively explained using the Shannon-Weaver diversity index (H'). The highest H' value was found for the 800-1000 m depth strata. The lowest number of species was observed between 1000 and 1500 m, which lowered the diversity index values (H'). The results of similarity percentage analysis (SIMPER) showed a change in the decapod fauna below 1000 m depth. The present results are preliminary; further data collection and analysis will be required to evaluate the role of palaeoecolgical conditions and trophic factors, and how these could be supposed to interact.