The impact of amur sleeper (Perccottus glenii Dybowsky, 1877) on the riverine ecosystem: food selectivity of amur sleeper in a recently colonized river

The presented study aimed at comprehensive assessment of the Perccottus glenii (Amur sleeper) impact on the aquatic ecosystem. Our objective was to analyze the diet, the characteristics of the prey and the feeding behavior of the Amur sleeper. Fish (349 individuals) were captured by electrofishing in autumn 2012. To estimate the dietary importance of each prey category, we calculated the percentage or proportion of each food item and its frequency of occurrence. The Costello graphical method was applied to describe the feeding strategy and prey importance. A total number of 55 taxa of benthic macroinvertebrates were identified, amounting to a total of 2448 individuals. The digestive tract was empty in 48 individuals of the Amur sleeper. The most frequent prey items of the Amur sleeper were Asellus aquaticus L, Baetis spp., the Chironomidae family which was represented by 22 taxa identified to the genus and species levels, Corixa spp. and Physa acuta Drap. Depending on the frequency of prey items, two categories of size classes with specific diet compositions in the Amur sleeper populations were determined. Feeding strategy, cluster indicators of the size classes and traits of macroinvertebrates were the main aspects covered by our study of the Amur sleeper feeding behavior.