The role of environmental factors on beta diversity of periphytic algae in a tropical reservoir

Context Understanding the effects of environmental filters on the beta diversity of periphytic algae is fundamental to understanding the functioning of tropical reservoirs. Aim To investigate how the presence and morphological complexity of macrophytes drives the increase in beta diversity of periphytic algae and whether environmental filters have direct effects on periphytic algae. Methods Periphytic algae were collected from macrophyte stands quarterly in the Jazigo reservoir, north-eastern Brazil. Alpha and beta diversity were measured between the different structural complexities of macrophytes. Key results Alpha and beta diversity, and turnover of periphytic algae were higher in macrophytes of higher complexity (Pontederia crassipes and Ludwigia helminthorrhiza) and nestedness was higher in macrophytes of lower complexity (Cyperus articulatus). Beta diversity was driven primarily by physical and chemical variables. Dissolved inorganic nitrogen, macrophyte complexity, temperature, macroinvertebrates, light and dissolved oxygen explained the beta diversity of periphytic algae. Conclusions These results suggest that environmental filters and the structural complexity of macrophytes are determinants for the increase in alpha and beta diversity of periphytic algae. Macrophytes with greater morphological complexity favour increased availability of niches and microhabitats, and greater diversity of periphytic algae. Implications Habitat simplification is one of the main threats to reducing biodiversity and homogenisation of aquatic communities.