Arctic marine mammals: The new canaries?

Submitted by Marie Gilbert
Phone: (907) 474-7412
02/17/06

FAIRBANKS, Alaska--It’s a fish-eats-krill, seal-eats-fish, bear-eats-seal world and a University of Alaska scientist hot on the trails of contaminants in Arctic food webs will present his and colleagues’ research on apex predators and biomagnification at the American Association for the Advancement of Science annual meeting Feb. 18 in St. Louis, Missouri.

Todd O’Hara, of the UAF Institute of Arctic Biology, and colleagues investigated three key Arctic apex predators: polar bears, arctic fox and coastal human residents and the increase in concentration of pollutants such as mercury, cadmium, and selected chlorinated pesticides--a process called biomagnification--from one part of a food web to another in these predators and their prey.

"Understanding contaminants in marine mammals is critically important to addressing oceans and human health in Alaska,"? said O’Hara, who will be presenting a seminar titled, "Biomagnification and pathways of contaminants in Arctic food webs"? and will participate in the press briefing, "Marine mammals: The new canaries?"? both on Feb. 18 at the AAAS meeting.

Heavy metals and chlorinated pesticides may alter normal biochemical and physiological functions such as reproduction and development in animals. They may also pose a risk to human health through food consumption. The common assumption was that the higher up the food chain or trophic level an animal ate the more contaminants it accumulated in its tissues. Researchers are finding this is not always the case. O’Hara and colleagues are investigating how marine mammals’ ability to biotransform or chemically alter substances affects biomagnification using stable isotope signatures and bioassays.

Predators such as bowhead whales and walrus which feed at low trophic or nutritional levels consume invertebrates such as krill and clams which typically have reduced exposure to mercury and many chlorinated pesticides. Yet, these same predators have increased exposure to cadmium, which accumulates in the liver and kidney. Apex predators such as polar bears, arctic fox, and killer whales feed at higher trophic levels--consuming fish and marine mammals--and typically have increased mercury and chlorinated pesticide exposure, but lower levels of cadmium.

Contaminant deposition in animal tissues is strongly dependent on factors such as diet, age, sex, body condition, and health and cross-species and cross-tissue comparisons must take this into account.

AAAS press briefing "Marine Mammals: The New Canaries?"? will be in room 274, second floor, America’s Center, Saturday, Feb. 18, 9 a.m. Central Time.

Contact: Todd O’Hara, Associate Professor of Wildlife Toxicology, Institute of Arctic Biology, University of Alaska Fairbanks, 907-474-1838, fftmo@uaf.edu

Marie Gilbert, Publications and Information Coordinator, Institute of Arctic Biology, University of Alaska Fairbanks, 907-474-7412, marie.gilbert@uaf.edu