Impact of environmental variables and food availability on rotifer assemblage in the karstic barrage Lake Visovac (Krka River, Croatia)

摘要

We evaluated the impact of 18 environmental variables (physico-chemical, nutrients, food resources) on rotifer assemblage in the sub-Mediterranean karstic barrage Lake Visovac. In terms of the spacetime distribution the highest density of rotifers was noted in the summer period (average 386 ind/l, relative annual abundance 62%), and in the epilimnetic layer (average 309 ind/l, relative annual abundance 58%). A total of 41 rotifer taxa belonging to 22 genera and 14 families were identified. Three rotifer species: Gastropus stylifer, Synchaeta tremula and Trichocerca birostris were dominant and perennial during the annual investigation. Pearson's product-moment correlations and canonical correlation analysis suggest that temperature, pH values, alkalinity, chemical oxygen demand and chlorophyll a concentration significantly influenced rotifer density. According to rotifer food collection and selection, in Visovac Lake macrofilter-feeders predominated, and microfilter-feeders were in a minority.