EFFECTS OF RE-SUSPENDED SEDIMENT ON THE PRIMARY PRODUCTION IN THE DONGHU LAKE

To examine the effect of suspended sediment on the primary production in the Donghu Lake, field investigation was carried out with the modified black and white bottles. The light intensity, nutrient concentrations and chlorophyll fluorescence were measured. The results showed that with the increased content of resuspended sediments, light intensity decreased significantly (P0.05), TP concentration and the maximum photochemical efficiency (Fv/Fm) increased significantly (P0.05), the respiration was significantly enhanced (P0.05), the gross primary productivity and net primary productivity increased at first and then decreased. Suspended sediment at 50100 g/L significantly increased primary productivity via the enrichment of the nutrient but dramatically repressed the gross primary productivity at 200 g/L even with a negative net primary productivity through significantly decreasing the light intensity in the water column (P0.05). We revealed the impacts of Donghu Channel project on the freshwater ecosystem of the Donghu Lake, which need further attention.