DIEL VARIABILITY IN THE OCCURRENCE OF JUVENILE FISH IN THE SHALLOW LITTORAL ZONE: DO MACROPHYTES IMPACT THE STRUCTURE OF FISH ASSEMBLAGES?
Andrzej Kapusta, Elżbieta Bogacka
Department of Ichthyology, The Stanisław Sakowicz Inland Fisheries Institute in Olsztyn, Poland
ABSTRACT. The aim of the research was to determine the diel variability of fish assemblage occurrence in aquatic vegetation which varied in both species composition and structure in the shallow littoral zone of a lake heated by power plant discharge waters. The fish were caught at three study sites of different habitats: dense, single-species aggregations of the macrophytes Nuphar lutea (L.) Sibth. & Sm. (NUL) and Vallisneria spiralis L. (VAS) as well as from fragments of the littoral zone overgrown with layers of V. spiralis (PVS). Eleven fish species representing five families were caught. The richest species composition was noted at the PVS site, although fish density was similar in all of the habitats. Two clear periods of fish activity occurred at all the study sites within the diel cycle.
Key words: JUVENILE FISH, MACROPHYTES, DIEL VARIATION, LITTORAL, HEATED LAKES
Dr Andrzej Kapusta, Instytut Rybactwa Śródlądowego, Zakład Ichtiologii, ul. Oczapowskiego 10, 10-719 Olsztyn; Tel./Fax:+48 89 5240171; e-mail: firstname.lastname@example.org