Dependence of fecundity on body length of the invasive species Gmelinoides fasciatus (Crustacea; Amphipoda) in Lake Onega

Abstract

For the first time in Lake Onega, the reproduction features of the alien amphipod Gmelinoides fasciatus (Stebbing, 1899) were studied based on research in 2010–2011. The period of reproduction in the conditions of the reservoir (May–September) were established, the body length ranges of egg-bearing females, the average and maximum sizes of breeding individuals, as well as fertility were determined. During the study period, a decrease in the average size of females from May–June to August–September was noted, which is associated with the beginning of reproduction of females of the summer generation and the continued reproduction of females of the last year's generation. Equations were calculated that make it possible to predict the fecundity of females by body length, which indicates similar patterns of generative growth of G. fasciatus on the littoral in the northern bays of Lake Onega. Generally, the fecundity of the amphipod is higher in Lake Onega compared to the fecundity of the same species in Lake Ladoga, Neva Bay, Lake Arakhley and the Bratsk Reservoir. This phenomenon is probably associated with the geographical location of Lake Onega, a higher latitude and a longer photoperiod.