Bioavailability and effects of organochlorine contaminants in relation to seasonal lipid cycles in arctic fox.

The project aims to study the influence of natural winter emaciation in an arctic top-predator on organochlorine contaminant tissue distribution, bioavailability and biological impact. Arctic animals utilize periods with high food availability for feeding and lipid deposition, whereas they rely on stored lipids during unfavourable periods. Hence, many arctic inhabitants exhibit profound seasonal cycles of fattening and emaciation. In the Arctic, feeding is associated with fat deposition and contaminant accumulation. When lipids are mobilized, accumulated contaminants are released into the circulation. Consequently, blood contaminant concentrations may increase markedly and result in a redistribution of the contaminant(s) from “insensitive”, adipose tissues to sensitive organs, and increased contaminant bioavailability. Such variations complicate interpretations of pollutant toxicity, both in effect studies and in monitoring programs, and remains an important future research area. In the present study, we will use the arctic fox (Alopex lagopus) as a model species for investigating tissue distribution and bioavailability of organochlorine contaminants in relation to natural variations in lipid status (field study).One old, male arctic fox, with low levels of body fat, was trapped in July in 2003, and we plan to trap up to 6 summer-adapted foxes between July and August 2004. We collected winter-adapted foxes, with high levels of body fat, from the annual fur-trapping season on Svalbard in 2003-2004.