Phytoplankton dynamics at a reservoir in northeast China

This study assessed the impact of water quality parameters on phytoplankton in the various spatial and seasonal scales of the Nierji reservoir. The research data covered three sites along the mainstream of the Nierji reservoir which is located in the northeast China. The seasonal and spatial variations were the essential factors regulating phytoplankton dynamics. Dominant influencing factors of the chlorophyll-a (Chl-a) content of phytoplankton were different according to the spatial and seasonal scales. Although total phosphorus was the limiting factor influencing the phytoplankton in the various spatial and seasonal scales, Chl-a was weakly correlated to total phosphorus in the upstream, midstream, and downstream during the flood season. A weak correlation between Chl-a and total nitrogen was found when ammonia nitrogen or nitrate displayed a stronger correlation with Chl-a. Ammonia nitrogen or nitrate was significantly correlated to total nitrogen when the correlation between Chl-a and total nitrogen was not significant. The Chl-a increased with decreasing the Secchi depth in the reservoir.