Environmental preservation leads to greater beta diversity of periphytic algae in Amazonian streams

Abstract

Changes in land use modify the structure of forests and the dynamics of streams. They cause changes in the chemical and physical environments, directly affecting the composition of the local aquatic biota. Our research sought to answer whether species composition is different between streams with different land uses; whether density is higher in locations with lower environmental integrity values; whether the richness and diversity of periphytic species are related to higher values of environmental integrity indices; and whether beta diversity is greater in streams in preserved areas. 18 streams were sampled in the Tapajós River basin, in a range of at least 100 km in the stretch that comprises the banks of the Amazon National Park and its surroundings, located in the southwest region of the State of Pará. Samples of periphytic algae were obtained from the Nymphaea amazonum Mart. & Zucc macrophyte. Our study demonstrated that streams located in preserved areas (national forest) differed environmentally from streams with agricultural land use and presented higher environmental integrity values. Species composition differed between different land uses. Environmental integrity had no effect on species diversity, richness and density. Beta diversity responded to different land uses, and the highest values were observed in streams from more intact environments. Our results showed that environmental variables had a greater influence on the structuring of the periphytic community than landscape variables. Preserved areas were important in environmental heterogeneity and in the formation of the structure of periphytic communities. Our study demonstrated that streams located in preserved areas differ from surrounding streams with different land uses, mainly because they present greater environmental integrity and greater variation in the beta diversity of periphytic algae.