Calculation of Oyster Benefits with a Bioenergetics Model of the Virginia Oyster.

摘要

A bioenergetics model is formulated and validated for the Virginia oyster (Crassostrea virginica). The model considers two basic properties of a bivalve population: number of individuals and individual size. Individuals are represented as three energy stores: soft tissue, shell, and reproductive material. The bioenergetics model is coupled to an oyster benefits module. The calculation of benefits is based on mass-balance principles and upon user- supplied values for parameters, including resuspension, sediment diagenesis, and dentrification rate. The bioenergetics model is coupled with a representation of the physical environment based on the tidal prism approach and with eutrophication kinetics from the CE-QUAL-ICM model. The bioenergetics model was demonstrated through application to the Great Wicomico River, Virginia, 2000 - 2009. An overarching conclusion from the application was that representation of the detailed data set collected in this system required corresponding detailed information on recruitment, mortality, and other factors. Calculations for the Great Wicomico indicated that 164 metric tons of carbon per annum was filtered from the water column by oysters and 15.2 tons was buried to deep inactive sediments. An additional 13 metric tons of carbon was buried in the form of shell. Oysters filtered 28 metric tons nitrogen per annum from the Great Wicomico water column. Most was recycled, but ultimately 6.2 metric tons nitrogen per annum was removed through denitrification and burial of oyster deposits. This nitrogen rate compared favorably with the 18.6 metric tons per annum calculated watershed load of total Kjeldahl nitrogen. The report concludes with recommended next steps. The two foremost recommendations are for additional validation through application to additional systems and for operation with the eutrophication kinetics activated.