Impact of vessels on sediment transport and diversity in Lake Taihu, China

In shallow lakes, waves from different sources play a major role in sediment transport and the release of associated nutrients. This study was conducted to analyze the impacts of waves generated by wind or vessels, on nutrient concentrations and microbial diversity in China’s third largest lake, Taihu. The study area is fixed at 100 m length of sailing vessel and 10 m width from where water samples were collected, near the Taihu Laboratory for Lake Ecosystem Research (TLLER) Station, at Meiliang Bay. The average flow velocity changed during passages of the vessel from -0.1 to + 0.1 m/s with high-speed vessel compering by the time before and after passages for one hour. The significant wave height ranged from 0.002 to 0.698 m. Turbidity ranged from 29.5 to 65.5 NTU. The concentration of Chl-a (μgL-1) and nutrients total nitrogen (TN), total phosphorus (TP), ammonium (NH4+) and phosphate (PO4) were resuspended in the three depths of the water column, as a response to the turbulence caused by waves-waves collision and rivers waves. Microbial amount concentration in the two layers changed over time. It increased in the surface from 5.03 to 8.3 ng µl-1 and decreased in the bottom from 5.03 µl-1 to 2.93 ng µl-1 over a 45 min period. This study points to the importance of sediment resuspension as a factor influencing nutrient availability and microbial community structure, and as such it plays an important role in the eutrophication dynamics of Lake Taihu.