Occurrence, dispersion and habitat preferences of Amur sleeper (Perccottus glenii) in oxbow lakes of a large river and its tributary

Abstract

Amur sleeper (Perccottus glenii) is currently one of the most invasive fish species in Europe. This inspired our research to identify potential channels of emigration in two rivers, the Vistula and the Wieprz. Amur sleeper occurrence, abundance, population size structure and impact on indicators of diversity were examined in oxbow lakes of both rivers. Amur sleeper was recorded for the first time in floodplain areas located between two rivers, which may serve as main travel corridors. Amur sleeper was noted in four out of six oxbow lakes in each river. Its relative abundance varied depending on the oxbow lake, ranging from 0.002 to 1.60 ind. m −2 in the basin of the Vistula River and from 0.04 to 0.35 ind. m −2 in the basin of the Wieprz River. Percentage share in the dominance structure ranged from 2.42 to 100 % and from 40 to over 67 % in the oxbow lakes of the Vistula River and Wieprz River, respectively. The size structure of the Amur sleeper populations was dominated by young individuals (Tl < 50 mm), which is characteristic of developing populations. The presence of Amur sleeper did not significantly affect biodiversity indicators. Its occurrence was related to the amount of vegetative cover.