Functional and taxonomic approaches differently highlight local and spatial processes in phytoplankton metacommunities

Despite advances in phytoplankton ecology through functional approaches, little is known about functional traits highlighting metacommunity processes. Our aim was to highlight and compare the influence of spatial and local environmental factors in a phytoplankton metacommunity, in a subtropical shallow lake system, based on taxonomic composition and different functional trait measures. Environmental filtering significantly explained metacommunity variation in most approaches. The spatial signal found could be interpreted as mass effects, given the scale of the present study, and was also a significantly driver of community variability. Among the functional measures, Morphology-Based Functional Groups revealed a stronger influence of the pure environmental component. Although the taxonomic approach helped capture variability in the local environment in a reliable way, it also showed the highest residual variance. Phytoplankton volume significantly captured both local and spatial processes under low residual variance, which may make it a promising functional trait for metacommunity studies. Our findings demonstrated that the drivers of phytoplankton metacommunity may be differently captured by taxonomic and functional measures, so that the approaches can eventually give more or less weight to the environmental and/or spatial signals. We thus recommend the use of taxonomic and functional approaches in metacommunity studies in a complementary way.