A single year of warmer-than-average Arctic temperatures can trigger malnutrition in ringed seals, intensifying risks to Inuit food security and northern ecosystems already stressed by environmental toxins, according to new research published today in Environmental Research.
The study, conducted by researchers at Simon Fraser University, analyzed blood, blubber, and liver samples from 38 Arctic ringed seals harvested in Labrador’s Saglek Bay and adjacent fjords between 2009 and 2011. Saglek Bay is a known hotspot for polychlorinated biphenyls (PCBs), contaminants remaining from a Cold War-era military radar station, as identified in 1996.
Researchers likewise measured levels of mercury, DDTs (synthetic insecticides), and chlordane, an older termite pesticide, in the seal tissues. Liver samples consistently showed high concentrations of all four contaminants across the three years of the study. These persistent organic pollutants, many of which are internationally banned, are known to cause oxidative stress – a form of cellular damage linked to inflammation, chronic disease, and reproductive health issues.
The analysis revealed a stark correlation between warmer temperatures and seal health. In 2010, when sea surface temperatures were 5.5°C above normal, seals exhibited depleted levels of omega-3 and omega-6 fatty acids, increased saturated fats, and thinner blubber layers – all indicators of malnutrition. “We saw that just one year of unusually warm temperatures and reduced ice is enough to change what these seals are eating and how their bodies process nutrients,” said Anaïs Remili, a postdoctoral fellow and lead author of the study.
The study also identified increased levels of methionine sulfoxide in the liver samples from 2010, a biomarker associated with oxidative stress. This suggests that the seals were experiencing inflammation, compromised immunity, metabolic disorders, and potential reproductive impacts.
PCBs, DDTs, and chlordane are lipophilic, meaning they accumulate in the fatty tissues – specifically the blubber – of marine mammals. As seals become nutritionally stressed and lose blubber, these stored contaminants are redistributed into the bloodstream, circulating throughout the body. “Thinner, nutritionally stressed seals redistribute the contaminants they had stored in their blubber back into the bloodstream, which then circulates through their entire system,” Remili explained. While the seals generally recovered from the 2010 malnutrition by 2011, researchers caution that future nutritional stress could exacerbate the long-term damage caused by oxidative stress.
The findings underscore the compounding threats facing Arctic ecosystems. Rapid sea ice loss and shifting marine food webs are already altering the seals’ diet. Climate change may also drive increased transport of pollutants into Arctic regions through altered ocean currents.
Tanya Brown, a marine mammal ecotoxicologist and senior author of the study, emphasized the importance of these findings for communities along the Labrador coast. “Healthy seal populations are essential for food security and cultural continuity,” she said, noting that local communities have long expressed concerns about the impacts of contaminants and warming conditions on both animal and human health.
