Using macrozoobenthos to assess the ecological condition of the Starzyc Lake (North-West Poland)

In the summer of 2008–2009 species composition and quantity of macrozoobenthos in deposits samples collected with Ekman gripping device at 4 points of Starzyc Lake was studied. Lake Starzyc also called Chociwel is located in West Pomeranian Voivodeship and is adjacent to the town of Chociwel from South and South East of the city. In the collected material of the analysed lake macrozoobenthos organisms from the following classes were found: Oligochaeta, Hirudinea, Crustacea, Insecta and Bivalvia. The Insecta class was the most numerous one in respect of species found, including larvae of the following orders: Ephemeroptera (Leptophlebia sp., Ephemera sp., Caenis macrura (Stephens)), Trichoptera (Limnephilidae, Leptoceridae, Cyrnus sp.) Diptera and Megaloptera (Sialis lutaria L.). The density and biomass distribution in the analysed Starzyc Lake demonstrates the occurrence of unfavourable changes which may lead to eutrophication in the shallowest layers of the body reservoir and in the zone at the depth of 4.9 m. The littoral zone of the studied lake features high density and significant benthic fauna biomass with low values of PIE biodiversity index.