LONG-TERM CHANGES IN 0+ FISH ASSEMBLAGES IN LITTORAL ZONES OF HEATED LAKES. II. SPECIES STRUCTURE OF ICHTHYOFAUNA
Vladimir G. Tereshchenko*, Andrzej Kapusta**, Halina Wilkońska**,
Aleksandra P. Strelnikova*
*The Papanin Institute of Biology of Inland Waters, Russian Academy of Sciences, Borok, Russia
**The Stanisław Sakowicz Inland Fisheries Institute in Olsztyn, Poland
ABSTRACT. The aim of the study was to describe changes in the biodiversity of 0+ fish assemblages inhabiting lakes that differed in morphometry and the intensity and period of water heating. During the study larvae and fry of fish belonging to 24 species, three faunal assemblages, and three termal groups were caught. The most species were from the boreal lowland (10) and Ponto-Caspian freshwater (10) complexes, while the least were from the amphiboreal freshwater (3) complex. In all of the lakes studied, the most abundantly occurring fish were those belonging to the Ponto-Caspian complex. However, in consideration of thermal requirements, it was confirmed that the most numerously represented species are thermophilic (15), while the least represented belonged to eurythermic species that spawn in late spring (3). The marked congruity of the ichthyofauna composition of the studied lakes resulted from the limited spatial isolation of the individual lakes and the similarity of the environmental conditions that shaped the 0+ fish assemblages.
Key words: FAUNISTIC COMPLEX, 0+ FISH, FISH ASSEMBLAGES, LITTORAL ZONE, HEATED LAKES