Food composition and feeding strategies of an invasive species, Carassius gibelio (Bloch, 1782) inhabiting a eutrophic lake in Middle Black Sea region

Abstract

Diet composition and feeding features of the Prussian carp Carassius gibelio (Bloch, 1782) were studied by analysing the stomach content of 155 fish specimens sampled from Lake Ladik during November 2009-October 2010. Five of the specimens had empty stomachs. A total of 29 prey taxa belonging to eight major groups comprising aquatic insects, Copepoda, Cladocera, Rotifera, Bacillariopyhta, Chlorophyta, Cyanobacteria and fish eggs were identified in 150 full stomachs. Diet composition showed slight seasonal variation. Cladocera was the most important prey item in all seasons, with peak abndance in spring. Feeding intensity exhibited seasonal change and was maximum in summer. Summer and autumn diets of this species showed the highest similarity. The study indicated that the Prussian carp in Lake Ladik showed both omnivorous and opportunistic feeding habits, exhibiting specialised feeding strategy on Cladocera, while they showed generalised feeding strategy on most prey items. The wide dietary plasticity of invasive Prussian carp can help their population to expand rapidly in different aquatic ecosystems. Keywords: Alien species, Diet composition, Feeding habits, Lake Ladik, Prussian carp