INFLUENCE OF SPECIES-SPECIFIC ATTRIBUTES ON DIETARY AND TISSUE-BASED EXPOSURE ASSESSMENTS OF TWO FISH-EATING BIRD SPECIES EXPOSED TO PCDFS AND PCDDS

Selection of receptor species is a critical step in formulating the study design of ecological risk assessments (ERAs). The great blue heron (Ardea herodias; GBH) and belted kingfisher (Ceryle alcyon; BKF) are piscivorous predators that are often selected as receptor species for ERAs pertaining to persistent bioaccumulative contaminants in aquatic environments. Both species have similar dietary compositions, however their exposure characteristics including metabolic rates, foraging range, and site fidelity may differ. Matching receptor characteristics to site attributes and risk management goals ultimately determines the value of any ERA. The primary objective of the present study was to investigate the influence of species ’ life history characteristics in the selection of the most effective receptor. Sediments and floodplain soils of the Tittabawassee River (TR) downstream of Midland, MI, USA contain total concentrations of the seventeen 2,3,7,8-substituted polychlorinated dibenzofurans (PCDFs) and dibenzo-p-dioxins (PCDDs) ranging from 1.0x102 to 5.4x104 ng/kg dw. These concentrations of PCDD/DFs in sediments and soils are some of the greatest reported and are 10- to 20-fold greater than the regional background. As apical avian piscivorous predators, GBH and BKF were selected as aquatic-based receptor species within a broad group of receptors in support o