Metal accumulation in fish from different zones of a large, shallow freshwater lake.

Metal (Cd, Pb, Cr, Ni, Mn, Cu, and Zn) concentrations in different fish species sampled from two distinct (phytoplankton- and macrophyte-dominated) lake zones of a large, shallow freshwater lake, Taihu Lake, were investigated. Concentrations of most metals in muscle of the small-sized fish (Protosalanx hyalocranius, Pseudorasbora parva, and Rhodeus ocellatus) were always significantly higher than those of the large-sized (Carassius auratus, Cyprinus carpio, and Aristichthys nobilis) and carnivorous fish (Pelteobagrus fulvidraco, Cultrichthys erythropterus, and Erythroculter ilishaeformis). Metal accumulation in the small-sized fish from the phytoplankton-dominated lake zone was always greater than those from the macrophyte-dominated lake zone in summer. However, no significant differences were observed between the two lake zones for most metals in the small-sized fish collected in winter. Metal accumulation in gills, liver, and intestine of the large-sized fish from the phytoplankton-dominated lake zone was generally greater than those from the macrophyte-dominated lake zone in summer. The presence of distinct ecological regions in the lake might affect the metal distribution in the small-sized or large-sized fish. For the carnivorous fish, however, metal concentrations in fish tissues from the two different lake zones were not significantly different, suggesting that metal accumulation in carnivorous fish might be less influenced by the ecological status of the lake.