Abstract :
[en] The cyanobacterial community composition in the mesotrophic Lake Blaarmeersen
was determined by denaturing gradient gel electrophoresis (DGGE) of PCRamplified
16S rRNA gene fragments during two consecutive years to assess the
importance of different classes of explanatory variables (bottom-up and top-down
factors, physical variables and phytoplankton) in cyanobacterial community
dynamics. The most dominant cyanobacteria in Lake Blaarmeersen were Synechococcus
(three genotypes), Limnothrix redekei and Anabaena/Aphanizomenon.
Analyses of Similarity revealed that the cyanobacterial community in Lake
Blaarmeersen differed significantly between the growing season and the winter
season as well as between the epilimnion and hypolimnion during the stratified
periods. Mantel tests revealed significant correlations between the DGGE data and
bottom-up factors, physical variables, the phytoplankton community composition
and, interestingly, the zooplankton community composition. In general, the
zooplankton community composition (especially the cladoceran community)
was more important in structuring the cyanobacterial community than the total
zooplankton biomass. This study shows that grazing zooplankton communities
can have a relatively strong impact on the cyanobacterial community dynamics
and that this impact can be equally important as bottom-up processes regulated by
nutrient concentrations and/or physical variables.
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