engleski

Effects of fish introduction on zooplankton community in an agricultural lake

The study was conducted in the spring of 2018 in Lake Jošava (Eastern Croatia) before and after stocking with common carp (Cyprinus carpio) was conducted. The aim of the study was to determine whether fish stocking affected the composition of planktonic and periphytic communities at different sites (pelagic P1-P4 and littoral L1-L4 zones) of the lake. Samples were collected for community composition analysis (zooplankton, phytoplankton, periphyton). A significant difference in physicochemical parameters was detected using the one-way ANOVA. Water depth, transparency, and total phosphorus concentration differed significantly between sites. The qualitative composition of the periphyton revealed a wide diversity of taxa from the Chrysophyta and Chlorophyta groups found. Species from the same groups were also most represented in the qualitative composition of the phytoplankton. Rotifers did not change significantly before and after restocking. The most abundant rotifer groups were Keratella and Brachionus. A quantitative difference was observed between the pelagic and littoral sites throughout the study, with a large proportion of biomass at the second pelagic site (P2) two weeks after restocking. There was an obvious trend of change within the dynamics of the zooplankton groups in relation to the timing of stocking. The lowest number of rotifers was recorded one week after fish stocking. After one month of stocking, the abundance of rotifers and crustaceans increased, indicating reduced fish predation

Cyprinus carpio ; zooplankton ; rotifers ; phytoplankton

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