The impacts of local and regional factors on the phytoplankton community dynamics in a temperate river, northern China

Abstract

Knowledge of the phytoplankton community dynamics is fundamentally important for river ecological management. Disentangling the relative impacts of co-occurring factors is critical to understanding the community responses to environmental heterogeneity, as well as anthropogenic activities. Taking phytoplankton community as the indicative variable, this study aimed at elucidating the impacts of driving forces (local factors: water environments; regional factors: land-use, fertilizers application, and socio-economic factors) on the phytoplankton community dynamics. We found that spatial and seasonal processes played a vital role in structuring the phytoplankton community, with Bacillariophyta and Chlorophyta accounting for>79.0% of taxa composition. Bacillariophyta had the highest cell density (>41%), followed by Cyanophyta (>20%) and Chlorophyta (>11%), which mainly contributed to the spatial and seasonal differences in the composition and abundance of the phytoplankton community. Meanwhile, local factors (such as total phosphorus, permanganate index, flow velocity, transparency, and stream depth) and regional factors (the application of phosphate fertilizers) (p < 0.05) were the dominant factors that influenced the phytoplankton community. Here, the phosphorus related factors interfered with the phytoplankton community on both local and regional scales. On the whole, the local factors (including nutrients and hydrology factors) have a more direct impacts on the phytoplankton community in a temperate river. It is of guiding significance for river ecology monitoring and improvement in north China, while paying attention to terrestrial influences, the eutrophication of the river itself still needs to be focused on accompanied with the hydrology factors.