Biogeochemical characteristics of coastal waters adjacent to small river-mangrove systems, East Brazil

This study addresses the composition of biogenic matter and the metabolic a ctivity of coastal waters of the eastern Brazilian shelf, bordered by small river-mangrove systems. Oceanic Brazil Current waters induce oligotrophic and near to homogeneous conditions of chemical constituents along the inner shelf. The impact of small river-mangrove systems upon coastal waters is m inor and of local nature. Bottom topography, coral reef habitats, and local upwelling also induce minor local spatial variability of dissolved inorgan ic and organic nutrients and O-2 and CO2 saturation levels in the coastal w aters. Metabolic activity during the daylight period, inferred from O-2 and CO2 saturation levels, varied from slightly autotrophic to heterotrophic.