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Temporal and spatial
changes in the horizontal distribution of planktonic Crustacea between
vegetated littoral zone and the zone of open water |
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Jan Igor Rybak1, Teresa Węgleńska2
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1Department
of Hydrobiology, University of
Warsaw, Banacha 2, 02-097 Warszawa, Poland, e-mail: igor@hydro.biol.uw.edu.pl 2
Formerly: Department of Hydrobiology, Institute of Ecology, Polish Academy of
Sciences, Dziekanów Leśny, Poland |
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Abstract:
The research concerned the
density, dominance structure and species composition of planktonic Crustacea
community, as well as their diel horizontal migrations between aggregations
of vegetation and open water in the littoral zone of two lakes. The Cladocera communities of sparse beds
of submerged macrophyte showed a sharp domination (>70%) of individuals of
large-sized tycholimnetic species. In the Cladocera community in a dense beds
of macrophyte also individuals of littoral species occurred in greater numbers.
The filamentous algal mats were mainly dominated by Copepoda and small tycholimnetic species of
Cladocera. We observed a sharp daily gradient of Crustacea density across macrophyte beds and open water. The greatest diel changes were found near the edge of the macrophyte beds (ecotone zone). Daytime density of Cladocera was several times greater in the macrophyte beds than in the open zone, while during the night-time density differences were not so marked. In contrast, in the case of filamentous algal mat, the sharp gradient of abundance remained constant by both day and night. An inverse
relationship between chlorophyll a concentration
and Cladocera density was noted in the transect between beds of submerged
macrophytes and open water, provide to effective control of phytoplankton
biomass by Cladocera during their diel migrations. |
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Key words: plankton Crustacea, submerged macrophytes,
filamentous algae, diel horizontal migrations |