engleski

Trophic relationship in the pelagic community of the Borovik reservoir three years after revitalization

The Borovik Reservoir (water surface 23 km2 ; mean depth cc 5 m), constructed in 1970, was emptied in 1993 and almost all fish were harvested. The objective of this study was to analyze the structure of the pelagic community and the trophic relationship in linear food chain: ichtyofauna – zooplankton – phytoplankton, three years after refilling of the reservoir. Sampling was done in two-week intervals between May and October 1996. According to the results of three catches, six fish species have been identified: carp, tench, prussian carp, common perch, sunfish and largemouth back bass. The most abundant were planctivorous fish, which had strong feeding pressure on the zooplankton. Small cladocerans and rotifers were dominated in the zooplamkton community. A significant correlation between chlorophyll-a and zooplankton density suggests that there was top-down impact of zooplankton on chlorophyll-a, i.e. the phytoplankton community, in which large inedible phytoplankton species were dominant. Top-down effects are evident from the top of the food web down to the phytoplankton level in the mesotrophic ecosystem of the Borovik Reservoir.

phytoplankton ; zooplankton ; fish ; trophic relationship

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