Demersal Lessepsian fish assemblage structure in the northern Levant and Aegean Seas

Demersal Lessepsian fish assemblage structure in the northern Levant and Aegean Seas

Murat Bilecenoğlu

Department of Biology, Faculty of Arts and Sciences, Adnan Menderes University, Aydın, TURKEY

Abstract

Spatial diversity and assemblage structure of Lessepsian fish were investigated, based on bottom trawlings carried out at the northern Levant and Aegean Sea coasts of Turkey. A total of 20 species were identified, with abundances gradually decreasing along the longitudinal gradient from east to west. Two species, Saurida lessepsianus and Equulites klunzingeri, made up 82.5% of the total Lessepsian fish catch, which were also responsible from the greatest portion of dissimilarity between Levant and Aegean Seas. The results of cluster and nMDS analyses based on a Bray-Curtis similarity value of 50% showed the presence of three different assemblages, revealing that the borders of Lessepsian province currently shows no sign of northwards expansion towards the northern Aegean Sea. Possible influence of six environmental variables on fish assemblage structure were tested; two (depth and water temperature) were found to be statistically significant by the Monte Carlo permutation test. Canonical correspondence analysis (CCA) showed that only Nemipterus randalli had a positive correlation with water temperature, while the remaining species either had a preference to shallow depths or cool waters.

Keywords: Lessepsian province, fish assemblage, Levant Sea, Aegean Sea