The coastal Pseudo-nitzschia from the state of Rio de Janeiro, Brazil

On the coast of the state of Rio de Janeiro, Brazil, there are 3 environments where Pseudo-nitzschia spp. are a frequent component of the micro-phytoplankton (detected in 70-80% of the samples): Cabo Frio (cape with seasonal upwelling), Guanabara Bay (heavily polluted estuary), and Ribeira Bay (pristine waters). Cell density can vary from 10 super(2) cells.L super(-1) (common in Cabo Frio) to a maximum value of 10 super(5) cells.L super(-1) (constant in Guanabara Bay and often found in Ribeira Bay). In Cabo Frio (1988-90), they contributed to the first stages of phytoplankton succession triggered by upwelling, but were also well represented in nutrient-poorer, warmer waters. In Guanabara Bay (1985-87, 1998-99), the occurrence and distribution of this marine genus was mostly determined by salinity gradients: lowest abundances (at times, none detected) in the inner reaches of the bay and during the rainy season (summer). In Ribeira Bay (1987-97), the homogeneity of local hydrological features allowed for the presence of the genus year around and at high relative contributions to the micro-phytoplankton (>50% of the total cell density). At present, eight species are identified using light and/or scanning electron microscopy: P. cuspidata, P. delicatissima, P. heimii, P. cf. multiseries, P. multistriata, P. pseudodelicatissima, P. pungens, and P. cf. subfraudulenta.