Macrozoobenthic community structure and water quality assessment of Lake Luoma, Jiangsu Province, China

Abstract

Physiochemical conditions and macrozoobenthos in Lake Luoma were investigated monthly in 2014. The lake was divided into three regions of the sand mining, the vegetation and the others according to its habitat conditions. Physiochemical parameters and macrozoobenthic community structure were compared among the three regions. Water quality was evaluated based on the surface water environmental quality standard (GB 3838-2002), comprehensive trophic level index and biological indices. The depth of sand mining area was significantly higher than that in the vegetation area, while the transparency was much lower than the other two regions. The concentrations of total nitrogen, total phosphorus, nitrate and phosphate in the sand mining area were significantly higher than those in the vegetation area, while the biodiversity indices of macrozoobenthos were significantly lower than the other two regions. A total of 41 taxa were identified, including 8 species of Annelida, 15 species of Mollusca and 18 species of Arthropoda. Bellamya aeruginosa, Branchiura sowerbyi, Limnodrilus hoffmeister and Alocinma longicornis dominated the community with high abundance and biomass. The annual average density and biomass of macrozoobenthos were 77.19±43.59 ind./m2 and 37.62±28.31 g/m2, respectively. Higher spatial heterogeneity was observed for the mean biomass than the mean density. The relative high mean biomass values were found in the littoral sampling sites while the relative low values in offshore sampling sites. It showed that the lake was moderately polluted at a mesotrophic level. As an important water source and aquaculture site, more attention should be paid on water environment protection in Lake Luoma.