LONG-TERM CHANGES IN 0+ FISH ASSEMBLAGES IN THE LITTORAL ZONE OF HEATED LAKES. I. DIVERSITY, EVENNES AND DYNAMIC PHASE PORTRAIT OF SPECIES STRUCTURE
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. A study was conducted from 1966 to 2000 to analyze the structure and characteristics of the dynamics of differentiation in the 0+ fish assemblages in lakes with varied morphometrics, intensity, and various periods of water heating. Species domination and variation were defined by characterizing the fish assemblages. The occurrence of 24 fish species belonging to 7 families was confirmed. Changes in the composition and variety of the autochthonous ichthyofauna resulted from water heating and increased water flow. The analysis of the phase diagram trajectory indicated instability and variation in the 0+ fish assemblages of the lakes that were heated most intensely. The fish assemblage that exhibited the greatest diversity fluctuation was noted in the lake heated the most and with the most stable water exchange. However, the most diverse 0+ fish assemblage structure was noted in the lake that was least transformed and received partially cooled water only during the summer.
Key words: DIVERSITY, JUVENILE FISH ASSEMBLAGES, DYNAMIC PHASE PORTRAIT, LITTORAL, HEATED LAKES