R/EH-10a

Strategic focus area:

Description:

OBJECTIVES: Our overall objective is to quantify how suspension-feeding organisms living attached to the hard substrate formed by oyster reefs serve to remove phytoplankton from the water column and thereby help improve water quality. Specifically, for hooked mussels and tunicates, two of the most abundant (by biomass) organisms on oyster reefs, we will: • Determine biomass-specific, temperature-dependent, and seston concentration-dependent rates of water filtration and biodeposition • Assess filtration efficiency for particles between 1 _ 50 μm • Develop a spreadsheet model that estimates non-oyster "filtration capacity," in terms of both total volume of water cleared of particles and mass of particles transferred to the sediments. METHODOLOGY: We will quantify biomass-specific, temperature- and seston concentration-dependent filtration rates, particle clearance rates, and particle size-dependent filtration efficiencies for mussels and tunicates in the laboratory. Our laboratory data will be combined with published oyster data to create a spreadsheet model to estimate the contribution of these non-oyster suspension-feeders to total reef filtration capacity. RATIONALE: Recently-developed ecosystem models used to predict effects of oyster restoration on various water quality parameters likely underestimate the benefits because they do not incorporate the filtration capacity of other suspension-feeding reef residents. Densities of mussels and tunicates often exceed 100 per square meter and can form a large portion of total reef biomass throughout Chesapeake Bay. We will quantify the filtration capacity of these species, allowing their incorporation into future ecosystem models.