Nutrient discharge has detrimental effects on coastal ecosystem and leads to impaired water quality. Nitrogen from fertilizers, livestock, runoff, wastewater treatment plants, and atmospheric deposition can lead to eutrophication - resulting in harmful algal blooms, dead zones, fish kills, and restricted sunlight to plants and algae. Oysters are known to act as a buffer for eutrophication through filter feeding; ultimately bio-extracting nitrogen from the surrounding water. Quantification of this process, and its utility compared to engineered wastewater treatment processes and other nutrient management strategies is complex. To better understand this relationship, models of oyster farms are used in Copano and Matagorda Bay along the Texas coast.
This study uses a three-step approach to evaluate the potential role of oyster mariculture as a water management tool. First, the Assessment of Estuarine and Trophic Status (ASSETS) model assesses vulnerability and eutrophication status of a bay’s condition based on hydrodynamic and biogeochemical measures. Second, the Farm Aquaculture Resource Management (FARM) model is used to estimate oyster harvest and associated nitrogen removal. Lastly, an economic value is assigned to oyster related nitrogen removal based on an avoided costs approach which uses costs of alternative nutrient removal strategies such as municipal wastewater treatment technologies. Nutrient credit trading is a relatively new endeavor, but it may provide a supplemental income for bivalve farmers in the future.Understanding the ecosystem services provided by oyster mariculture and natural reefs can create a sustainable management approach, and increase resiliency of our coastal bays and estuaries.