Epiphytic Algal Biodiversity in Humic Shallow Lakes from the Lower Parana River Basin (Argentina)

We analyzed the algal composition (including Cyanobacteria) of epiphyton on macrophytes and the environmental data from five water bodies of a wetland from the Natural Reserve Otamendi (NRO) located in the Parana River Basin, South America, during one year. Also, we described the diversity patterns (alpha, beta, and gamma diversity) of the epiphyton in the wetland. We selected two different macrophytes: the emergent rush Schoenoplectus californicus and the free-floating liverwort Ricciocarpus natans. We found 105 epiphytic taxa, of which 48% were represented by Bacillariophyceae, 22% were Cyanobacteria, 18% were Chlorophyta, and the rest (12%) belonged to Euglenophyta, Xanthophyceae, Synurophyceae and Cryptophyta. The structure of the epiphytic assemblage changed in relation to water level fluctuations, showing a major proportion of planktonic, metaphytic, and ticoplanktonic components during high water phases. The overall low algal richness may be related to the low light penetration in this humic wetland. The geographical pattern in taxa turnover was explained by the combination of metapopulation dynamics (dispersal distance) and continuum theories (infrequent connectivity followed by spatial differences associated in geographic habitat differences). Water level fluctuations affected the epiphytes on S. californicus, while temperature and light penetration influenced the epiphytes on R. natans.