Quantifying Nitrogen Removal Potential in Oyster Reefs Versus Aquaculture in Response to Hydrodynamic Setting and Water Quality
2020 - 2022
University of Maryland Center for Environmental Science
Lora Harris, University of Maryland Center for Environmental Sciences, Chesapeake Biological Laboratory; Lawrence Sanford, University of Maryland Center for Environmental Science, Horn Point Laboratory
Strategic focus area:
Healthy coastal ecosystems
Current efforts to restore natural oyster reefs and a growing oyster aquaculture industry in Maryland will serve to support an increased prevalence of oysters in Chesapeake Bay. While these activities will support continued commercial harvests and restored natural habitats, elevated oyster numbers will also lead to changes in estuarine biogeochemistry relevant to water quality restoration. Recent studies have illustrated that oyster communities are associated with extremely high rates of nitrogen removal and newly proposed BMP guidelines will serve to give nitrogen removal credits to aquaculture activities. Despite efforts to ‘scale-up’ nitrogen losses from oyster communities in ecosystem-scale budgets, there remains uncertainty in the differences in nitrogen losses in aquaculture versus natural reef settings, due to stark contrasts in the fate of biodeposits as a function of local hydrodynamic conditions. This research aims to apply a newly-developed, fine scale model system for oyster filtration, biodeposit production and transport, and sediment and reef nitrogen cycling to quantify nitrogen loss rates in aquaculture and natural reef conditions under a variety of hydrodynamic settings. Model simulations will be constrained and validated by a series of empirical measurements of current velocity, water-column conditions, biodeposit deposition, and sediment properties made at aquaculture and natural reef locations at several locations across Maryland tidal waters. The resulting estimates of nitrogen removal in contrasting oyster growth settings will provide much-needed quantitative information to support how oyster BMPs are credited and help select ideal locations to optimize nitrogen loss and avoid over accumulation of biodeposits in aquaculture leases in Maryland. At the culmination of the proposed project, we aim to gather a diversity of stakeholders in the oyster aquaculture community to evaluate model simulations of nitrogen removal under of varying conditions of oyster density and hydrodynamic settings.