Spatial variation of periphytic desmid community structure on emergent macrophytes in a tropical urban watershed

Desmids are one of the most representative groups of algae in oligo-mesotrophic aquatic environments. They respond to environmental changes and can be used as indicators of water quality. We evaluated changes in the structure of desmid communities on emergent macrophytes in relation to environmental conditions at a spatial scale in two rivers in a tropical urban basin in the State of Bahia, Brazil. Sampling was carried out every two months for one year at five fixed stations. Changes in the desmid community structure were associated with variations in limnological conditions, which differed between the sampling stations. We observed increases in total phosphorus concentration and conductivity from upstream to downstream, which influenced the changes in desmid community structure. Desmid richness and total density were higher in urban, recreational, and more preserved areas. In conclusion, phosphorus availability associated with land use and urbanization influenced desmid community structure variability in coastal plain rivers.