Biologist Rune Dietz of Denmark’s National Environmental Research Institute has been investigating the contaminants in the marine environment that find their way into the animals’ vital organs, blubber, and other tissues -- even their tusks -- via the food chain. While no studies have yet been conducted that have evaluated the health effects of contaminants like heavy metals and industrial chemicals on narwhals, Dietz found elevated levels of cadmium, selenium and mercury, as well as man-made organochlorines like PCBs and DDT, in tissue samples collected from 150 narwhals in Greenland.
|Photo courtesy of Glenn Williams|
Dietz isn’t the only scientist examining narwhal tissue samples to better understand the health of the population. University of Manitoba scientist Gary Stern has collected samples of narwhal livers, kidneys, muscle and blubber to assess contaminants in the whales, and his results somewhat mirror those of Dietz. He said that climate change may be exacerbating the problem because the accumulation of contaminants in narwhal tissues is dependent on the whales getting access to those contaminants. As sea ice retreats, he said that more contaminated fish will be available for the whales to feed upon, making those contaminants “bioavailable.”
While Stern agrees with Dietz that little is known about the health impacts of these pollutants, he worries most about what he calls the “synergistic effects” from a wide range of challenges the animals are facing.
“It’s hard to tell what affects the contaminants are having on their health, but they are one additional stressor they have to deal with,” he said. “We still have no information that says directly that it’s affecting reproduction or having neurological effects; it’s hard to tell with an animal in the wild. But these animals are under stress for a number of reasons – changing habitat, noise pollution – and contaminants are just another thing that acts synergistically to possibly making their immune systems not work as well.”