Carrying capacity of bivalve aquaculture
A framework was developed for determining carrying capacity through mass-balance ecosystem modeling and stakeholder involvement that can be used to guide management of bivalve aquaculture. A collaborative working group was formed where stakeholders worked closely with scientists to calculate carrying capacity which was then used to inform a long-term aquaculture plan for Narragansett Bay and Rhode Island's coastal lagoons where aquaculture has doubled in six years and user conflicts are high. Stakeholders informed the modeling process at four critical steps: conceptualization of models, evaluation of data sources for parameterization, mass-balancing of the model, and calculation of carrying capacity. Cultured oysters, at current and carrying capacity biomass levels calculated in the models, have insignificant impact on the ecosystems of Narragansett Bay and the lagoons, despite rapid increase in the industry. Cultured oyster biomass in Narragansett Bay is currently 0.5 t km-2y-1 and could be increased 625 times without exceeding the ecological carrying capacity, a density of aquaculture development above which causes unacceptable ecological impacts (297 t km -2y-1). Production carrying capacity, the density at which harvests are maximized irrespective of ecosystem condition, was calculated to be 3,481 t km-2y-1. Cultured oyster biomass in the lagoons is currently 12 t km-2y-1 and could increase 62 times this value without exceeding the ecological carrying capacity (722 t km-2y-1). Production carrying capacity was calculated to be 1,561 t km-2y-1. Together, Narragansett Bay and the lagoons are capable of producing a total biomass of 119,436 t of cultured oysters in a total area of 374 km 2 at ecological carrying capacity which is comparable to peak historic (1911) levels. Historical, current, and modeled harvests were approximately 40% of total biomass. Both Narragansett Bay and the lagoons had higher carrying capacities per unit area than oligotrophic and heavily cultured New Zealand bays. RI systems are heterotrophic detrital systems receiving 71% of energy from detritus. The importance of detritus should not be overlooked when considering available food sources for shellfish. Involving stakeholders in the modeling process increased understanding and acceptance of the science thereby making the results more likely to be incorporated into future aquaculture management and policy formulation.
Ecology|Environmental science|Aquatic sciences
Carrie Jean Byron,
"Carrying capacity of bivalve aquaculture"
Dissertations and Master's Theses (Campus Access).