engleski

Copepods vs Cladocerans: Long Term Changes in the Crustacean Zooplankton Community of the Butoniga Reservoir (Croatia)

Long term changes in crustacean plankton assemblages in varying limnological gradients of the Butoniga Reservoir (Croatia) were investigated in a time period of 20 years. The reservoir was built to serve a number of purposes: flood protection, water supplv and irrigation. Numerous phvsical and chemical variables measured during the investigation classifv the Butoniga Reservoir as a meso-eutrophic water body. However, we observed a decrease in total phosphorus, COD, ammonia and chlorophyll a concentration during the last six years. These changes were accompanied with shifts in the crustacean plankton community. From 1987 until 1999 small bodied cladocerans, the micro-filter-feeders: Bosmina longirostris. (Miiller, 1785) and Diaphanosoma brachyurum (Lievin, 1848) and omnivorous cyclopoids dominated. In 2001 the cladoceran community has changed, with the micro-filter-feeder Ceriodaphnia quandrangula (Miiller, 1785) appearing in higher numbers. The most prominent change was noticed in 2002 when large herbivorous species, like Daphnia sp. and the calanoid Eudiaptomus gracilis (Sars, 1863) took over the crustacean community of Butoniga Reservoir.

crustacean plankton; hydrological parameters; Butoniga reservoir

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