Response of the cladoceran community to eutrophication, fish introductions and degradation of the macrophyte vegetation in Lake Dianchi, a large, shallow plateau lake in southwestern China

A paleolimnological evaluation was made in order to analyze the effects of increasing nutrient load, macrophyte degradation and fish introductions on the cladoceran community of a large, shallow plateau lake in southwestern China. The trophic state of Lake Dianchi has increased rapidly during recent decades, its macrophyte vegetation has suffered severe degradation, and fish introductions in the late 1950s and early 1980s have had a marked effect on the structure of the fish community. Our results show an increase in abundance of cladoceran species with a preference for eutrophic conditions over the last few decades, while species preferring oligotrophic conditions have decreased or disappeared. These changes correspond to the eutrophication in Lake Dianchi. The loss of the cladocerans Kurzia latissima and Disparalonarostrata is likely to be a reflection of the degradation of the macrophyte community. An increase in Daphnia body size indicated by the ephippia length since the early 1990s is associated with the decline of planktivorous species.