BACTERIAL DENSITY AND BIOMASS, AND RELATIONS WHITH ABIOTIC FACTORS, IN 14 COASTAL LAGOONS OF RIO DE JANEIRO STATE

Abstract

The aim of this study was to evaluate the bacterial density and biomass in the water column of 14 coastal lagoons of Rio de Janeiro State. Furthermore, we relate these bacterial variables with chlorophyll a concentrations and abiotic factors, such as salinity and concentration of nutrients. High values of bacterial density and biomass were observed in these lagoons, mainly in lagoons with high salinity. In salty lagoons, we also observed a strong dominance of long rods, which contribute to the high biomass observed. We conclude that, during the period observed, these lagoons with high salinity can be considered extreme environments, selecting few species of bacteria that could live there. There is a strong correlation between bacterial density and biomass with phosphorus concentration in these lagoons. No other correlation among bacterial density and biomass with abiotic factors or chlorophyll a were found. Thus, in this case, phosphorus can be considered the main limiting nutrient to bacterioplankton in most of these coastal lagoons. These coastal lagoons presented high concentrations of dissolved organic carbon (DOC), but similar concentrations did not result in similar water color. We conclude that the DOC from these lagoons must have different origins, which can interfere in its utilization by the bacterial community.