The relative importance of dispersal and local factors in structuring phytoplankton communities in high mountain lakes in the Pyrenees

Evaluating the relative contributions of local environmental versus regional spatial descriptors to the shaping of phytoplankton communities provides an understanding of the community dynamics of high mountain lakes. The present study elucidated the role of lake morphometric, physicochemical, biological, and spatial descriptors in determining the patterns in phytoplankton diversity and community composition based on taxonomic and morphologically based functional groups. We collected samples of phytoplankton, zooplankton, and abiotic variables from 24 Pyrenean lakes. The influence of environmental factors on alpha diversity was analyzed using generalized linear models, and the influence on beta diversity was analyzed using linear regressions. To detect biogeographical patterns, we performed Mantel correlation tests, and to identify the environmental drivers of the phytoplankton community composition, we performed redundancy analysis. We found that only local environmental factors significantly contributed to the phytoplankton community structure in high mountain lakes, with nutrient- and light-associated variables being the major drivers of local and regional diversity and compositional variations. Our results suggested that total phosphorus significantly affects alpha and beta diversity patterns. This study highlighted that niche-related local factors are the main drivers to explain phytoplankton composition, and that dispersal limitation is not notably influential in high mountain lakes within the Pyrenean Lake district.