Diatoms from the most hypersaline lagoon in Brazil: Vermelha lagoon

Scarce knowledge is available concerning the diatom ecology of hypersaline environments and their potential to use as bioindicators. The aim of this study was to characterize and quantify diatom assemblages from Vermelha Lagoon associated with environmental parameters in order to establish environmental quality bioindicators for hypersaline environments. Species distribution displayed a weak relationship with environmental parameters analyzed in DCA analyses. The cluster analyses evidenced the presence of four diatom groups in the lagoon: Group I - located on the south margin of the lagoon, represented by N. arenaria; Group II - located in the north, the central sector and near the communication channel with Araruama Lagoon, dominated by F. interposita. The Group III - distributed in the shallowest regions, where primary productivity is high. Species H. acutiuscula and C. placentula in this group reached high relative abundance values. Group IV is characterized by increased salinity and lipids values, characterizing hypertrophic sediment conditions. These stations were located in the Saltpan water catchment and were characterized by a decreased number of species and the dominance of A. robusta.