O'Hara 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 February 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.
Contact: Marie Gilbert
University of Alaska Fairbanks