Phytoplankton assemblages in a newly man-made shallow lake and surrounding canals, Shanghai, China

Abstract

Ecological community assembly has been one of the central issues in ecology. In this study, twenty sites were selected in a shallow man-made lake and its surrounding canals in Shanghai, China. We examined monthly phytoplankton assemblages during 2010–2012, with the use of cluster and ordination analysis, to identify phytoplankton assemblages patterns. Our results indicated that phytoplankton assemblages varied along a gradient of turbidity and nutrients. The large canal with ample nutrients and high turbidity was dominated by diatoms (e.g., Navicula cryptocephala). Flagellates (e.g., Cryptomonas erosa, Chlamydomonas globosa and Euglena oxyuris) dominated in the canals with the decreased nutrient and turbidity. Dinoflagellates (e.g., Gymnodinium sp.) were abundant in the lake. The lake experienced drastic changes in physico-chemical conditions since its creation in 2003, such as desalination and nutrient enrichment. Phytoplankton assemblages trajectories followed environmental changes closely. A relatively stable seasonal cyclic character in the phytoplankton development was observed in lake during 2010–2012. These results suggested that local environmental constraints can be strong enough to structure local phytoplankton assemblages in this highly interconnected system.