engleski

Ecological conditions of population development of species Synchaeta tremula (rotifer) in the Visovac lake

The aim of this study research was to establish the seasonal population dynamics of the rotifer species Synchaeta tremula on a vertical profile in the lake Visovac, depending on the food competition in the zooplankton community and on seasonal fluctuations of available food resources. In the zooplankton of the Visovac lake rotifer S. tremula was the most dominant representative of the rotifer fauna. Its percentage share varied from 1 % to 94 % of the total rotifera abundance. The population development started at beginning of summer and the maximum population density was achieved in epilimnion up to a depth of 10 m in October. Suppressing of the population development of S. tremula in summer period was caused by the food competition pressure of more competitive species cladocerans, copepods and the rotifer Gastropus stilifer. On the other hand the population maximum achieved in autumn was in accordance with a drop in the competition pressure and an autumn increase in phytoplankton biomass as an available food resource. We presume that the occurrence of hypoxia in metalimnion and hipolimnion can be a limited factor to population development of rotifer S. tremula in deeper layers, too.

rotifers; Synchaeta tremula; kartic lake

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