engleski

Impact of water level fluctuation in shaping of plankton community

Shallow lakes are important water bodies in view of great biodiversity and landscape heterogeneity. These lakes are negatively affected by global climate changes, reflected in significant parameters of ecosystem deterioration, e. g. biodiversity decrease, macrophytes absence and water turbidity. During the 2012 and 2013 year we conducted zooplankton research in the Škrčev kut oxbow lake, (Krapina River watershed, NW Croatia, Europe) and set following goals: (i) to determine the effect of changes in hydrological regime and macrophyte coverage on the zooplankton structure and top down control ; (ii) to compare the abundance and diversity of zooplankton in a short-term scale. Within one year period water level increased for 2 meters. This caused significant reduction of floating-leaved macrophytes (i.e. Nuphar lutea), while turbidity, total phosphorus and chlorophyll a concentrations increased. Those, altered, ecological conditions were reflected in zooplankton community shift. Identified plankton assemblage suggested fish preference to cladocerans as main food source and enhanced notable increase of rotifer and copepod abundance. Prevalence on microfilter-feeder rotifers was evident during the both study period with the trend of their advancement. Our results indicate that, even on short-term scale, plankton community is directly influenced by modification of environmental conditions.

shallow lakes; zooplankton; macrophytes

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