DIET OF THE CHINESE MITTEN CRAB, ERIOCHEIR SINENSIS H. MILNE EDWARDS, 1853, AND POTENTIAL EFFECTS OF THE CRAB ON THE AQUATIC COMMUNITY IN THE RIVER ODRA/ODER ESTUARY (N.-W. POLAND)

The results of an analysis of the autumn diet of the Chinese mitten crab, Eriocheir sinensis, are presented and the crab's effects on the most common species of the flora and fauna of the River Odra estuary are assessed. Examination of crab gut contents showed the diet to be composed of detritus (59.6%), vascular plants (10.7%), and animals, mainly copepods and chironomid larvae (10.4%). The crabs, kept for 2 months in tanks under abiotic and biotic conditions similar to those prevailing in the Odra estuary, diminished the biomass of aquatic plants (particularly that of Elodea canadensis) by almost 12%, and that of aquatic macroinvertebrates (26% reduction of chironomid biomass and more than 21% reduction of tubificid biomass), which, at a high abundance of the crab, may have an adverse effect on the composition of species of plants and animals in the estuary.