Bioaccumulation of trace metals in zebra mussels

In this thesis, I conducted a series of experiments and field analyses to explore whether trace element concentrations in zebra mussel tissues are proportional to measurable fluxes into and out of tissues. I evaluated metal uptake from water and a variety of living and abiotic particles representative of seston in the Hudson River and other freshwater ecosystems. I also determined whether quantitative influx and efflux parameters, used in conjunction with ultra-clean measurements of trace elements on suspended particles and in water, can account for the major processes governing bioaccumulation in natural waters. This was done by developing a bioenergetic-based kinetic model of trace metal bioaccumulation in zebra mussels and by field-testing this model at sites on Lakes Erie and Ontario and the Niagara and Hudson Rivers.; Radiotracer methods were used to determine influx and efflux rates of 110mAg, 109Cd, 51Cr, 14C, 203Hg and 75Se into and from zebra mussel tissues by measuring assimilation efficiencies (AE) from diverse foods (phytoplankton, bacteria, natural seston assemblages, mineral particles), uptake rate constants of dissolved elements, and long-term efflux (depuration) rates. AEs of Ag, Cd and Hg (and Se less) correlated with both GPT and % intracellular digestion, indicating that the digestive gland is an efficient site for metal assimilation by zebra mussels.; Body burdens of Ag, Cr, Hg and Se predicted by our model using the above parameters and ultra-clean trace element measurements were within 30% of independently-measured body burdens (NOAA's NS&T Program) for these locations, and the model predicted variations in bioaccumulation factors between locations of up to 6-fold (for Ag). This study provides quantitative support for the application of the zebra mussel as a biomonitor of metal contamination in fresh water.; Zebra mussels absorbed algal-derived DOC with a 0.23% efficiency (DOC absorbed/DOC supplied). Absorption of dissolved Ag, Cd, and Hg greatly increased with increasing high-molecular-weight DOC concentration, while Se(IV) uptake was unaffected. (Abstract shortened by UMI.)...