Benthic respiration and inorganic nutrient fluxes in the estuarine region of Patos Lagoon (Brazil)

In situ benthic flux chamber experiments were performed during late austral spring and early summer of 1996 at eleven nearshore locations in the southern Patos Lagoon, Brazil. The Patos Lagoon is the largest lagoonal system in South America and is a very important nursery ground for local fin fish and shell fish fisheries. These are the first benthic flux measurements made in Patos Lagoon and they suggest that remineralization within the sediments may dominate the recycling of organic matter and nutrients in the lagoon. Measured oxygen benthic fluxes (45-160 mmol m(-2) d(-1)) are sufficient to remineralize reported mean water column carbon fixation while phosphate and fixed nitrogen benthic fluxes (-0.4-2 and -1.1-4.2 mmol m(-2) d(-1), respectively) are sufficient to supply 100% and 25% of the required water column nutrient demand, respectively. Although of limited areal and temporal coverage, these initial studies demonstrate that sediments play a major role in the metabolism and nutrient cycling within the Patos Lagoon Estuary and that future studies of lagoonal biogeochemistry must consider exchange with the bottom.