Temporal and spatial changes in the horizontal distribution of planktonic Crustacea between vegetated littoral zone and the zone of open water

Pages 205-218 : illustrations ; 27 cm

Bibliographical references (pages 217-218)

Strony 205-218 : ilustracje ; 27 cm

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.

Bibliografia na stronach 217-218