Ecological distribution of demersal fish species in space and time on the shelf of Antalya Gulf, Turkey

Abstract

This study provides baseline data on demersal fish assemblages in a heterogeneous but little-studied portion of the shelf of Antalya Gulf. The distribution of fish abundances along three transects subject to different fishing regulations, at depths of 10, 25, 75, 125 and 200 m, was studied between May 2014 and February 2015 in the winter, spring, summer and autumn months. A total of 147 species belonging to 69 families were sampled. Lessepsian migrants from the Indo-Pacific region made up about a quarter of all species collected and some of them were found to greatly influence community structure. The spatial distribution of fish species was driven mainly by bathymetric gradient and two main assemblages were observed: shallow waters (10–25 m) and deep waters (75–125 m; 125–200 m). Significant differences in community structure were found with regard to all the main variables: depth, transect, season and their interactions. Environmental variables measured concurrently with trawling were tested for correlation with fish abundances by canonical correspondence analysis (CCA). The results showed that the distribution of all species depends first on water depth and second on bottom type. The possible effects of fishing restrictions in the eastern part of the study area on assemblages are also discussed. In general, the spatial distribution and ecological processes of the fish community seem to depend on small variations in local environmental characteristics.