NUTRIENT EXCRETION BY Limnodrilus hoffmeisteri Claparède IN LAKE TAIHU, A LARGE, SHALLOW LAKE OF CHINA

摘要

To study the potential significance of Limnodrilus hoffmeisteri, a dominant benthic organism in Lake Taihu, on lake eutrophication, the effect of temperature and density on the ammonium (NH4+-N) and phosphate (PO43--P) excretion rates of L. hoffmeisteri was performed. Using a regression equation describing the relationship between temperature and the NH4+-N and PO43--P excretion rates of L. hoffmeisteri while considering water temperature and L. hoffmeisteri biomass in Taihu between 2007–2010, we estimated the potential nitrogen and phosphorus contribution of L. hoffmeisteri to Lake Taihu. With increasing temperature, both the NH4+-N and PO43--P excretion rates of L. hoffmeisteri gradually increased while changes in density did not significantly affect the excretion rate of NH4+-N and PO43--P. The annual average NH4+-N and PO43--P excretion by L. hoffmeisteri were 1925.54 and 210.0 t, respectively. These amounts were up to 19.3 and 23.3% of the annual NH4+-N and PO43--P net flux of the entire sedimentwater interface in Lake Taihu, and are only less than the two primary exogenous nutrient sources—indirect lakeside and watercourse nitrogen and phosphorus inputs. This study showed that nutrient excretion of L. hoffmeisteri has a significant effect on eutrophication in Lake Taihu.