Community structure of demersal assemblages in the southwestern Black Sea

Available knowledge on the assemblage patterns of demersal macro-faunal species in the Black Sea is scarce. For this reason, data series of demersal trawl surveys between 2011 and 2014 were collected to identify the demersal assemblages along the continental shelf in the southwestern Black Sea. Data were analysed from 146 demersal trawl hauls conducted in the spring and autumn periods for three bathymetric contours: 0–20 m, 20–50 m, and 50–100m. The spatial and temporal structural patterns of demersal zonation were assessed using multivariate analyses. Out of a total of 78 taxa, 69 demersal species were identified. Fishes showed the highest diversity with 41 species followed by 16 mollusks, 11 crustaceans, 5 echinoderms, 1 tunicate, and 1 porifera. Multivariate analyses revealed significant differences in the assemblages according to depth, sub-region, season, and year. Statistically, depth was the most influential factor determining the ordination of the faunal zonation. This study concludes that Merlangius merlangus, Mullus barbatus, Mytilus galloprovincialis, and Liocarcinus depurator may be the indicator species that make the greatest contribution to the formation of the demersal macro-community.