System-wide submerged aquatic vegetation model for Chesapeake Bay

A predictive model of submerged aquatic vegetation (SAV) biomass is coupled to a eutrophication model of Chesapeake Bay. Domain of the model includes the mainstem of the bay as well as tidal portions of major embayments and t ributaries. Three SAV communities are modeled: ZOSTERA, RUPPIA, and FRESHWA TER. The model successfully computes the spatial distribution and abundance of SAV for the period 1985-1994. Spatial distribution is primarily determi ned by computed light attenuation. Sensitivity analysis to reductions in nu trient and solids loads indicates nutrient controls will enhance abundance primarily in areas that presently support SAV. Restoration of SAV to areas in which it does not presently exist requires solids controls, alone or in combination with nutrient controls. For regions in which SAV populations ex ist at the refuge level or greater, improvements in SAV abundance are expec ted within 2 to 10 years of load reductions. For regions in which no refuge population exists, recovery time is unpredictable and will depend on propa gule supply.