Pigment-based chemotaxonomy of phytoplankton in the Patos Lagoon estuary (Brazil) and adjacent coast

ABSTRACTThe composition and distribution of phytoplankton assemblages were studied monthly at two sites in the Patos Lagoon estuary and at one site on the adjacent coast over three years (May 2012–April 2015). Samples were collected for microscopic examination and high-performance-liquid-chromatography pigment analysis. The pigment data were analysed using CHEMTAX software to estimate the contribution of different taxonomic groups to total chlorophyll a (Chl a). Phytoplankton assemblages were generally dominated by diatoms, which contributed, on average, 51% of the total Chl a, especially at the Cassino Beach surf zone, where Asterionellopsis guyunusae was the main species contributing to the high diatom-associated biomass. Cyanobacteria appeared as an important group at the lagoon’s mouth station, contributing, on average, 37% of the total Chl a. Cryptophytes, chlorophytes, prasinophytes and dinoflagellates were less important and contributed, on average, 13, 7, 5 and 3%, respectively, of the total phyto...