WA3 Metals and Bioaccumulation
254 Portland Ballroom
8:00 AM - 12:00 PM, Wednesday
() Biodynamics: A unifying principle that explains the variability in metal bioaccumulation.
Luoma, S1, 2, Rainbow, P 2, 1 US Geological Survey, Menlo Park, CA, USA2 The Natural History Museum, London, United Kingdom
ABSTRACT- A unifying principle is needed to explain the complexities that characterize metal bioaccumulation in nature. We propose that a broad solution lies in a biologically-based conceptualization, centered around biodynamic or biokinetic models. The model components include site-specific, high quality geochemical analyses, and species-specific parameterization of key physiological constants: influx rates from water, influx rates from food, rate constants of loss, and growth rates (when high). A number of publications have forecast bioaccumulation from these models for bioindicator taxa in specific ecosystems, and compared the forecasts to data from the same, resident, taxa in the field. The comparisons cover concentrations over 7 orders of magnitude, six metals, ten species of animals from three phyla, and marine, estuarine and freshwater ecosystems. When compiled, the regression coefficient (R2) between forecasts and independently observations from the field was 0.98. Most forecasts agreed with observations within two fold. Examples of biodynamics explain why species differ in magnitude and patterns of metal bioaccumulation, why bioaccumulation differs widely among metals, account for differences among ecosystems, and identify some limits to the approach. Site-specific forecasts are more variable than comparisons among species or metals, and might benefit from experiments tailoring physiological constants to specific circumstances, and better geochemical data. To link bioaccumulation and chronic toxicity, taxa-specific estimates of total bioaccumulated metal are being combined with taxa-specific knowledge of internal fractionation between detoxified and metabolically active metals. Modern protocols make such an approach feasible. The resulting biological specificity in evaluating metal effects is essential to understanding what species will be most affected by metals, and thus how ecosystems might be changed by metal pollution. This might be a more feasible approach to addressing chronic toxicity in nature than geochemically-oriented alternatives or those that require quantifying metal binding at all active sites.
Key words: metals, bioaccumulation, biodynamic, models