The feeding ecology of the Chinese mitten crab Eriocheir sinensis was studied by analyzing the stomach fullness and its content with regard to sex, size and brackish water habitats occurring on the coast of the Baltic Sea (Gulf of Gdańsk and Vistula Lagoon, Poland) and the Atlantic (Tagus Estuary, Portugal). The presented results show that neither the site, sex (except the Gulf of Gdańsk) nor the size of an individual had a significant (p > 0.05) effect on the stomach fullness of E. sinensis. However, the type of food consumed was significantly (p < 0.05) correlated with the inhabited locality. The stomachs of crabs contained the remains of animal and plant origin, as well as detritus. The remains of animals (Bivalvia, Amphipoda, Gastropoda and Polychaeta) were more frequently found in the crabs from the Gulf of Gdańsk, while the remains of plants (Tracheophyta, Chlorophyta) were most often found in the stomachs of crabs from the Vistula Lagoon and the Tagus Estuary. Detritus was found only in the Gulf of Gdańsk and the Vistula Lagoon. Research indicates that the feeding ecology of omnivore E. sinensis is habitat specific, which should be taken into account when assessing the risk associated with this invasive species.
