Gobiids of the Dniprodzerzhynsk Reservoir (Dnieper River, Ukraine): distribution and habitat preferences

Abstract

Didenko A.V. 2013. Gobiids of the Dniprodzerzhynsk Reservoir (Dnieper River, Ukraine): distribution and habitat preferences. Acta Ichthyol. Piscat. 43 (4): 257–266. Background. The Dniprodzerzhynsk reservoir is one of six reservoirs built on the Dnieper River, which currently supports important commercial and recreational fisheries. To date, there are no published data on the reservoir’s non-commercial fish species, among which gobies are considered to be the most abundant and important species. The goal of this work was to contribute to general knowledge on local gobiid fauna, focusing on their mesohabitat preferences. Materials and methods. Sampling in the Dniprodzerzhynsk reservoir was conducted during late August of 2011 and 2012 within the framework of routine annual juvenile fish surveys in the Dnieper reservoirs. Fish were collected at sampling sites located along the reservoir shoreline using a beach seine made of mill sieving gauze (1 mm mesh size). Mesohabitat features were recorded at each beach seine haul site, and included maximum depth, substrate type, and vegetation density. These data were used to identify fish mesohabitat preferences with the aid of Ivlev’s electivity index. Results. Seven gobiid species were collected: western tubenose goby, Proterorhinus semilunaris (Heckel, 1837); knout goby, Mesogobius batrachocephalus (Pallas, 1814); Pontian monkey goby, Neogobius fluviatilis (Pallas, 1814); round goby, N. melanostomus (Pallas, 1814); racer goby, Babka gymnotrachelus (Kessler, 1857); Pontian bighead goby, Ponticola kessleri (Gunter, 1861); and ratan goby, Ponticola ratan (von Nordmann, 1840). Ratan goby was recorded for the first time from this reservoir. Most frequently encountered were monkey goby (76.27%), followed by western tubenose goby (32.20%), racer goby (31.36%), round goby (14.41%), bighead goby (10.17%), while knout and ratan gobies were the most rare (each accounting for 1.69%). All gobiids showed preferences for certain mesohabitat features such as bottom substrate and aquatic vegetation density. Conclusion. The gobiid fauna of the reservoir is rich and is dominated by monkey goby. The occurrence of ratan goby, an estuarine and marine species that adapted to freshwater conditions, is an evidence for ongoing PontoCaspian gobiid invasion to the Dnieper reservoirs.