Small fish communities in two regions of the Liangzi Lake, China, with or without submersed macrophytes

Small fish communities were compared between the vegetated and vegetation-f ree regions of the Liangzi Lake, a shallow lake along the middle reach of t he Yangtze River, China. Fish were sampled using 10 x 10 m(2) block nets an d poisoning. Three samples were taken from either the near shore area or la ke centre of each region. A total of 19 fish species were collected; all sp ecies occurred in the vegetated region but only 12 occurred in the vegetati on-free region. The dominant small fish were Carassius auratus auratus in t he vegetated region and Ctenogobius giurinus in the vegetation-free region. Diversity, density and biomass of small fishes were significantly higher i n the vegetated region than in the vegetation-free region in both near shor e and lake centre areas. In the vegetated region, density and biomass of sm all fishes was significantly higher, while species diversity significantly lower in the near shore area than in the lake centre. In the vegetation-fre e region, density of small fishes was significantly higher in the near shor e area than in the lake centre area, but species diversity or biomass was u naffected by location.