Spatio-temporal variations of microphytobenthic biomass were investigated in the Botafogo and Siri estuaries, Pernambuco - Brazil. Samples were taken during low water (bi-monthly) from February to December, 2003. Three sampling stations were located in each estuary, in both midlittoral and sublittoral areas. Clear spatial and temporal variations were found for both chlorophyll-a and phaeopigment concentrations. In Botafogo, chlorophyll-a had 34% of total variation explained by MRA from nitrogen and phosphorus concentrations, while only 16% of total variation was thus explained from nitrogen concentration in the Siri estuary. Phaeopigments had 39% of total variation explained by MRA from nitrogen concentration and salinity in the Botafogo estuary and 58% of total variation was similarly explained from nitrogen concentration in the Siri estuary. Nitrogen was discriminated by the b coefficients as the most important factor in the explanation of the microphytobenthic pigments variations in the Botafogo estuary. The data of this study emphasize the role of nutrients and suggest that both estuaries show evidence of eutrophication.
microphytobenthos; chlorophyll-a; phaeopigments; biomass; nutrients