Polar bear health assessment in relation to toxicants and climate change

Project Description
Short Title: BearHealth
Project URL: http://www.biologi.no/bearhealth-eng.htm
Proposal URL: http://classic.ipy.org/development/eoi/proposal-details.php?id=134

Global atmospheric and oceanic pathways and processes result in the deposition of semi-volatile organic contaminants in the Arctic. With the ratification of the Stockholm POPs protocol the Arctic has become a strategic location with which to monitor global contaminants. Polar bears are top arctic predators, and hunted regularly by indigenous people, which so far has not been a threat to the stability of circumpolar subpopulation numbers. Polar bears are also captured and released for various research and monitoring porojects and thus accessible for biosampling. Polar bears are therefore ideal biomonitors of spatial and temporal distribution, dynamics, fate, biomagnification and potential effects of legacy and emerging organic contaminants of anthropogenic origin and present in the arctic environment. Furthermore, polar bears are indicators of ecosystem health and environmental change such as in sea ice habitat due to global warming. POPs and mercury and their concentrations in polar bear fat have been corelated to a number of biomarker endpoints of various effects including bone density, histology of immunological organs, renal lesions, liver morphology, immune function and/or hormones in polar bears from Svalbard, East Greenland and the Canadian Arctic.

Polar bears are exposed to a wide range of organohalogen contaminants at relatively high concentrations because of their high trophic level dependence as well as their preference to the blubber of their prey. For example, POP studies carried out in the circumpolar Arctic have shown high levels of selected POPs in polar bears from especially East Greenland, Svalbard and Russian Arctic. The highest levels POPs such as oxychlordane, trans-nonachlor and p,p-DDE were found in bears from Franz Josef Land and Kara Sea in the Russian Arctic. Polar bears from the Western Russian Arctic are exposed to higher levels of chlordanes and p,p-DDE than polar bears from locations westwards and eastwards from this region. Bears from the Western Russian Arctic (Franz Josef Land and Kara Sea) also had highest PCB levels compared to Svalbard, East Siberian and Chukchi Sea. A number of POPs such as PBDE, PFOS and chlorinated compounds are expected to increase to high levels.

By 2007-2008 it will be almost a decade since the last semi-circumpolar assessment of the spatial and temporal distribution of legacy and emerging POPs, and their metabolic by-products, was conducted in polar bears. Furthermore, the last truly circumpolar assessment, including bears from the Russian Arctic, will have been at least 15 years past. Emerging contaminants such as polybrominated diphenyl ethers (PBDEs) and other brominated flame retardant compounds and perfluorinated compounds, have also yet to be determined in polar bears from the Russian Arctic. In addition, two related IPY pre-proposals are also being submitted, with essentially the same international, collaborative team, to assess the circumpolar, spatial and temporal distribution of legacy and emerging contaminants - including the rising mercury levels in the Western Arctic - in polar bear and ringed seal (blubber), which is the major dietary species for polar bears.

Therefore, we propose to examine region-specific effect parameters (histology on internal organs, bone morphology) from necropsy samples taken via local Inuit hunters and haematology samples from the on-going telemetry studies, clitoris biopsies and rectal, vaginal and tracheal swabs and blood samples for bacteriology/virology, cytology and parasitology, vitamin and hormone profiles. These will be linked to the potential relationship between regionally bioaccumulation differences for the organohalogen contaminants and mercury levels. Fatty acid profiles and stable isotopes will also be determined to assess region-specific similarities and differences in polar bear diets linked to habitat climate factors - such as ice extent - from climate changes. Futhermore, genetical analysis would be helpful in the differentiaton of subpopulations in relation to hunting and management. This will be facilitated through the IUCN PBSG (Polar Bear Specialist Group) lead by Denmark as given in the resolutions from the last meeting in Seattle, June 2005. Beside this, a large Danish-Greenland research programme with numeours international scientific cooperation partners has been on-going since 1999, with several international published peer-reviewed papers.

The present study would follow up previous work by resampling the same polar bear subpopulations with the help of polar bear biologists and hunters in circumpolar countries, with extension to populations in the Russian Arctic. This proposed project will build on the network of interested scientists in Alaska (USA), Nunavut/Canada, Greenland/Denmark and Norway, as well as new Russian collaborators, that was established in 2000-2001. The proposed study would complement polar bear and ringed seal programs envisaged under IPY, or ongoing in each country, which are focussed, broadly speaking, on marine mammal ecology including polar bears. It would also link to human health and social integrity studies related to traditional diet and contaminants as well as climate changes. The project would use a common protocol for sample collection (timing, tissue type, preservation) and analysis. Chemical analysis would be done in 3-4 Canadian, Danish and Alascian labs (few specialised analyses might be done by a single specialized lab) while the pathological/micro pathogen analyses may be done at different national labs. Tissues would be archived for future chemical analyses. The contaminant results would be interpreted in terms of temporal trends (compared to previous studies on the same populations), spatial trends (especially of new contaminants) and potential for effects on polar bears and by extension to human exposure. In addition markers of climate changes will be developed, analysed and interpreted.