Spatial variability of phytoplankton in a shallow tidal freshwater system reveals complex controls on abundance and community structure.

•Landscape-scale experiment to evaluate drivers on phytoplankton abundance and community attributes.•Use of multiple approaches across gradients of nutrients, light, and water residence time.•Enclosure experiments and models may not identify landscape-level controls on phytoplankton.•Water residence time may be strongest control on phytoplankton community.