Recent studies have made disturbing discoveries about the health and condition of wolves living on Pleasant Island in coastal Alaska. Wildlife research biologist Gretchen H. Roffler and her team recently published a study that revealed some shocking truths. As a result, they’ve learned that these wolves have extremely elevated levels of mercury in their bodies, largely due to eating about 70% of their diet as sea otters. Here’s why this study is so important. Among other things, it addresses the serious ecological effects of mercury exposure, including its effects on wildlife in this region.
It drew comparisons between mercury concentrations found in the Pleasant Island wolves and mainland populations and interior Alaska. These results showed that wolves from Pleasant Island had the highest mercury levels of all populations studied. This is a disturbing trend with dire implications for our ecosystem’s health. It stands to threaten imperiled wildlife and, in turn, the human communities that rely on these animals.
Research Findings
Roffler’s incredible research spanned years, requiring the collection of baseline dietary data from wolf populations. This beloved female wolf—known as No. 202006—would spend nearly a year in Pinedale for naught and suddenly died in late 2020. While conducting necropsies, the team faced a troubling scenario. This four-year-old wolf displayed some of the highest levels of mercury ever recorded in her liver, kidneys, and other tissues.
“We spent quite a bit of time trying to figure out the cause of her death by doing a necropsy and different analyses of tissues,” said Roffler.
This unexpected death highlights the urgent need for further investigation into how mercury affects wolf health and the overall ecosystem.
“What finally came up was really unprecedented concentrations of mercury in this wolf’s liver and kidneys and other tissues,” Roffler added.
Overall, the study’s findings highlight a pervasive problem. As evidence that changes in the environment can significantly reduce mercury in wildlife.
The Role of Climate Change
Ecotoxicologist Ben Barst highlighted the link between climate change and mercury as an example of the intersection of these two issues. He pointed out that glaciers in coastal Alaska are retreating at some of the fastest rates on Earth. Climate change accelerated thawing of permafrost can release large amounts of mercury that have been locked away in bedrock.
“We know that glaciers can release a tremendous amount of mercury,” Barst stated.
He said that with glaciers melting, they are rising up, releasing particulate bedrock and some of that is laced with mercury. The ultimate fate of this mercury remains unknown. It might become buried in sediments or it might be converted into methylmercury—a much more toxic form of mercury that makes its way into the food web.
“With that melting of glaciers, you get release of the particulate bedrock and some of that bedrock contains mercury—and so we don’t really know the fate of that mercury,” Barst noted. “It may just get buried in sediments or it may actually be available for conversion to methyl [mercury] and get into the food web.”
Barst’s team is working hard to build positive dynamics. They are committed to learning how mercury may impact wolf health, as evidenced by their long-term concurrent research.
Dietary Implications
Wolves on Pleasant Island mostly eat sea otters. These otters are the indirect stars of an impressive and complicated nearshore marine food web. This anthropogenic dietary choice has made these wolves more susceptible to bioaccumulating mercury to dangerous levels. Their mainland relatives primarily seek moose and rarely if ever consume sea otters.
“They’re eating so many sea otters that they’re just getting this higher dose of mercury and it accumulates over time,” Barst explained.
The extreme degree of mercury intake presents grave dangers. This has implications that go beyond the wolves themselves, extending to other keystone species that are threatened by the silent massacre. The new study points to a problem that is much more pervasive than believed.
“It turns out that this might be a more widespread phenomenon than we thought originally,” Roffler said.
The data they collected raises very troubling questions about health risks to the wolves. Even more worryingly, it has created a perfect storm for other species who call their home habitat.