Polyculture bioremediation: an analysis of potential nitrogen assimilation and removal by Mya arenaria, Gracilaria tikvahiae and Ulva lactuca harvests in the Corsica river, MD

Abstract

An analysis of nitrogen bioremediation in a tidal tributary of the Chesapeake Bay by the use of a hypothetical bivalve and macroalgae polyculture covering 1%, 3% and 5% of the Corsica River bottom area. This study was performed to illustrate the role ecosystem services play in managing diffuse watershed pollution, particularly nitrogen, resulting in water quality and living resource degradation. Excess concentrations of nitrogen in the Corsica River estuary lead to seasonal eutrophication and subsequent hypoxic events. Mya arenaria L. and Gracilaria tikvahiae (McLachlan, 1979) were chosen for this theoretical study due to their high assimilative capacities for nitrogen and established commercial value, whereas Ulva lactuca L. was analyzed as a biofouling harvest to increase the harvest nitrogen sink. M. arenaria nitrogen assimilation was calculated from literature values of nitrogen content in tissue, whereas G. tikvahiae was simulated from an existing macroalgae submodel. M. arenaria nitrogen removal ranged from 1000 kg N to 7000 kg of nitrogen per year and did not reflect M. arenaria mortality or nitrogen remineralization from biodeposits. Simulation of the model indicates that G. tikvahiae can remove between 51-255 kg of nitrogen per year and U. lactuca only removes 35-103 kg of nitrogen per year. Results indicate that the polyculture of M. arenaria and G. tikvahiae in the Corsica River can adequately reduce net nitrogen levels and demonstrate the use of bioremediation as a possible nutrient management tool for estuary restoration.