RELATIONSHIP BETWEEN THE ABUNDANCE OF LARVAE AND JUVENILE STAGE ASSEMBLAGES AND THE OCCURRENCE OF MACROPHYTES IN THE SHALLOW LITTORAL OF LAKE LICHEŃSKIE
The Stanisław Sakowicz Inland Fisheries Institute in Olsztyn, Poland
ABSTRACT. The aim of this paper was to identify the relationship between the degree of macrophyte cover on the lake bottom and the abundance and species richness of larva and juvenile stage assemblages. The analysis of the material verified the hypothesis that as the surface area of macrophyte cover increases so does the abundance, species richness, and diversity of fish aggregations. The investigations were conducted in the heated Lake Licheńskie in 2000-2003 during the period when underwater vegetation is at the height of development (June – September). The spatial differentiation of macrophyte occurrence had a significant impact on the occurrence and differentiation of the fry assemblages. It was confirmed that along with an increase in the macrophyte cover surface area there was also an increase in the species richness and diversity of juvenile fish assemblages. The locations that were most densely overgrown with vegetation had the highest fish biomass and individual weight. In littoral areas without macrophytes, abundant single-species concentrations of fish occurred. The bottom macrophyte cover did not have an impact on the numbers of fish.
Key words: JUVENILE STAGES, BOTTOM MACROPHYTE COVER, SPECIES RICHNESS, DIVERSITY, HEATED LAKES
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