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1J - Bioaccumulation (WE9/9) ABAM (Avian BioAccumulation Model), a three life-stage model of bioaccumulation and toxicokinetics of POPs in wild birds and their eggs. Norstrom, Ross1, 2, Enright, Michael2, Leung, Brian3, Droulliard, Ken4, 1 Environmnent Canada, Ottawa, ON, Canada2 Carleton University, Ottawa, ON, Canada3 University of Notre Dame, Notre Dame, IN, USA4 University of Windsor, Windsor, ON, Canada ABSTRACT- Carnivorous and piscivorous birds are among the wildlife species most affected by bioaccumulation of POPs. We have some understanding of food intake rate and toxicokinetics of a few POPs in adults of a limited number of species, but little understanding of the overall bioaccumulation process and how to model it in wild birds. There are no existing models which deal with the complete life stage of a bird from egg to egg. The Canadian Wildlife Service has been studying levels and toxicokinetics of POPs in herring gulls and their eggs, as well as feeding ecology, reproductive success and other aspects of their biology in the Great Lakes for nearly 30 years. This wealth of information provided an unprecedented opportunity to create and validate a general model of POP bioaccumulation in birds: the Avian BioAccumulation Model (ABAM). ABAM is divided into three life stages: embryo, chick and adult. Uptake rates in embryos are determined from an experimentally-derived empirical equation. Gross energy requirements of chicks and adults are derived from an equation for the minimal activity existence energy budget of a non-passerine bird as a function of body mass, ambient temperature and photoperiod, plus cost of foraging of the adults (including feeding of chicks). POP uptake rate is based on gross energy requirement, diet composition, diet energy density, and POP concentration in diet. Toxicokinetics in chicks and adults are based on experimentally-determined clearance rates in herring gull juveniles and a two compartment model. The whole-body lipid compartment size is varied with ambient temperature to simulate actual conditions. The model is written in VB with an Excel spreadsheet interface for ease of input and output. A high degree of flexibility is built into ABAM to allow porting to other species without rewriting and recompiling the model code, e.g., energetic and growth equations can be altered, and parameters and constants redefined on the fly. The model and its validation for herring gulls in Lake Ontario will be presented. Key words: bioaccumulation, POPs, birds, eggs |
