Responses of zooplankton to ecological restoration in Wuli Bay of Lake Taihu, a subtropical shallow lake in China

摘要

Classical biomanipulation uses partial or complete elimination of zooplanktivorous fishes (intensive fishing, piscivore enhancement, or shocking) to enhance grazing pressure of herbivorous zooplankton on phytoplankton (Lazzaro 1997), especially in shallow eutrophic lakes where intense grazing on phytoplankton by daphnia leads to greater water clarity and lower algal biomass (Mehner et al. 2002). Biomanipulation was introduced by Shapiro et al. (1975) as a complementary measure to engineering approaches for lake restoration from eutrophication (Lazzaro 1997). From that time, manipulative food web experiments in enclosures and whole-lake manipulations have been widely studied (Benn-dorf 1990, Gulati et al. 1990, Gulatt & van Donk 2002). Biomanipulation has now become a routine technique for reducing algal biomass and enhancing water clarity of lakes and reservoirs (Kasprzak et al. 2002).rnHowever, differences in biological interactions in temperate versus subtropical lakes may make it difficult to directly apply biomanipulation methods that have been used in temperate systems (Jeppesen et al. 2005). Little is known about the role of zooplankton in warm lakes, such as Lake Taihu, a large subtropical shallow eutrophic lake in China. The species composition, density, and biomass of zooplankton and environmental parameters were investigated in Lake Wuli, a northern bay of Lake Taihu. Large numbers of aquatic mac-rophytes were planted inside a large enclosure near shore, and biomanipulation was carried out from February 2004 to December 2005.