The Significance of Stone Moroko, Pseudorasbora Parva (Temminck and Schlegel), in the Small-Sized Fish Assemblages in the Littoral Zone of the Heated Lake Licheńskie

The aim of the study was to determine changes in the seasonal abundance of stone moroko, Pseudorasbora parva (Temminck and Schlegel), and to identify the role this alien species plays in the littoral zone of a heated lake. This study also aimed at defining the habitat preferences of this species and describing the relations between the relative abundance of stone moroko and the occurrence of submerged vegetation. A significant dependence was determined of the degree to which the lake bottom is covered with macrophytes and the occurrence of stone moroko. The fish caught belonged to 14 species and 2 families. Stone moroko preferred habitats that were abundantly overgrown with submerged vegetation and avoided areas devoid of macrophytes. Thus, as the bottom cover increased, so did the relative number of this fish. In light of habitat availability and its food preferences, the abundant occurrence of this species poses a serious threat to the endemic ichthyofauna.