A LABORATORY STUDY TO QUANTIFY THE INFLUENCE OF NEREIS-DIVERSICOLOR MULLER,O.F. IN THE EXCHANGE OF PHOSPHATE BETWEEN SEDIMENT AND WATER

Fluxes of phosphate and oxygen across the sediment-water interface have been measured under different abundances of Nereis diversicolor in order to quantify their influence in this process. Results show that an increase of Nereis abundance results in a decrease in the gradient of dissolved phosphate in the interstitial water, and in the ratio calculated flux (J(o)) in the interface/diffusive flux, based on the pore water concentration gradients (J(d)) increase as well. The stoichiometry of oxygen consumption by sediment and phosphate release decreases when Nereis was present in the sediment. Mass balance calculated for total carbon, nitrogen and phosphorus revealed a loss of nitrogen from the sediment and some net accumulation of carbon and phosphorus.