Inverview with Dr. Jules Blais

Authors
Blais JM, Kimpe LE, McMahon D, Keatley BE, Mallory ML, Douglas MS, Smol JP.

Title:
Arctic Seabirds Transport Marine-Derived Contaminants

Source:
Science. 309: 445, 2005.

Summary:
The accumulation of industrial contaminants has been widely documented in the Arctic. It is now known that the cold environment and pattern of wind currents facilitates the deposition of contaminants from global pollution sources into the Arctic seas. Scientists have also discovered pockets of contamination inland from the coast in some regions of the Arctic. It has been suggested that migratory species may play an important role in the creation of these pollution hot-spots by transporting pollutants from the ocean to inland sites. Arctic seabirds are a key component of the ecosystem, as their nitrogen rich excrement nourishes mosses and lichen which are integral components of the food chain for Arctic wildlife. Most of these seabirds feed on fish, zooplankton, squid and carrion from the ocean, and can be found in very large breeding colonies of more than 20,000 individuals. The biological pump these seabirds provide is a crucial source of nutrients for terrestrial life, but may also be responsible for the concentration of contaminants in areas near their nesting sites. Seabirds feed near the top of the marine food chain, and therefore have the potential to accumulate a large burden of pollutants from contaminated food sources.

Blais et al. examined the relationship between seabird populations and pond contaminant levels on Devon Island located in the Canadian Arctic, close to Greenland. The investigators studied the contaminants in the surface sediments and water of Arctic ponds below the cliffs at Cape Vera, which is the nesting site for a large colony of northern fulmars. Eleven ponds in total were investigated; eight of these were selected due to the varying extent of fulmar influence, and three ponds were located in areas not thought to be influenced by seabird populations. Stable isotope ratios of nitrogen, which is enriched in guano relative to other nitrogen sources in the area, was quantified in the sediment of each pond, and used as a proxy for the extent of seabird influence. Levels of dichlorodiphenyltrichloroethane (DDT), mercury, hexachlorobenzene (HCB), and other organochlorine compounds were quantified in the sediment and water of each pond and plotted against the stable isotope ratio of nitrogen.

Ponds which were under the greatest influence of seabird guano input had up to 10 times the amount of HCB, 25 times the amount of mercury, and 60 times the amount of DDT as compared to the ponds with little or no influence from seabird populations. In addition, it was found that the ratio DDE (a biologically processed metabolite of DDT) to the parent compound was the highest in ponds most affected by seabird influence. This finding adds further evidence to support a biological mode of contaminant transport to these areas.

The results of this study indicate that Arctic seabirds are involved in the biomagnification and biological transport of pollutants from contaminated Arctic waters to remote areas where they nest. Some of the contaminants investigated in this study are suspected to have endocrine disrupting properties and therefore accumulation of these compounds in the environment has the potential to impact human health. This is especially relevant for the indigenous peoples of the Arctic as traditional foods remain an important component of the diet.