Salt marshes in South Brazil hold an unknown diatom community. This study aims to evaluate the composition, richness and β-diversity of the diatom community of salt marsh sediments in the Patos Lagoon Estuary. The samples were taken at five sites between 31º59'18.60"S - 52º14'58.50"W and 32º06'49.74"S - 52º09'22.57"W, in January 2002 and March 2008. The community was composed of 64% brackish, 24% marine and 16% freshwater diatoms and it was represented by 24 families, 36 genera and 50 specific and infra-specific taxa. There was no variation in the species composition indicated by β-diversity (1.05). Based on the Chao2 richness estimate, the diatom community is representative of the salt marsh in the Patos Lagoon Estuary. Measurements and illustrations of the species are presented.
floristic composition; richness; subtropical; β-diversity
