Bold claim: A single unusually warm year can destabilize Arctic life, not just a single species. A new study shows ringed seals face a double danger: climate-driven nutritional stress and a dangerous buildup of contaminants in their bodies.
Led by researchers from Simon Fraser University, the work reveals that warmer conditions can alter the seals’ diet while also hindering their ability to detoxify harmful chemicals. As temperatures rise and sea ice retreats, these seals struggle to find healthy, nutrient-rich prey, compounding the problem of contaminant exposure.
Why this matters goes beyond the seals themselves. Ringed seals are a key link in the Arctic food web: they eat small invertebrates and fish, and top predators like polar bears rely on them for sustenance. Inuit communities also depend on ringed seals for food security and cultural heritage. Senior author Tanya Brown emphasizes that warmer conditions can shift what seals eat, which in turn changes their exposure to contaminants and can affect overall health and survival. If the health of ringed seals falters, the effects ripple through the entire Arctic ecosystem and even impact people who rely on these networks.
A closer look at seal health
Researchers studied 38 Arctic ringed seals from Saglek Bay and nearby Northern Labrador fjords, collecting blood, blubber, and liver samples between 2009 and 2011. Saglek Bay is a known hotspot for polychlorinated biphenyls (PCBs), toxic chemicals historically released from a Cold War-era radar station. Scientists also tested for mercury, DDTs, and chlordane. Although many of these substances have been banned, they persist in the environment for decades.
Liver analyses showed elevated levels of PCBs, mercury, DDTs, and chlordane across all three years, indicating potential oxidative stress. This type of stress damages cells and is linked to inflammation, weaker immunity, chronic disease, and reproductive problems.
Signs of malnutrition in a warm year
The year 2010 stood out, with sea surface temperatures soaring about 5.5 degrees Celsius above normal and Arctic sea ice levels unusually low. Blood and blubber from 2010 revealed clear malnutrition indicators: lower levels of essential fatty acids like omega-3 and omega-6, increased saturated fat, and thinner blubber layers. Blubber not only stores energy but also insulates the animal in frigid waters; thinning blubber reduces both energy reserves and warmth protection.
A warmer year likely shifted the seals’ prey, reducing access to nutrient-rich food and altering how their bodies process nutrients. Anaïs Remili, the study’s lead author and a postdoctoral fellow, notes that just one abnormally warm year can change both diet and nutrient processing.
How contaminants build up and spread
Many of the hazardous chemicals found in the seals are persistent pollutants that travel long distances via air and ocean currents, reaching even remote Arctic regions. These compounds are lipophilic, meaning they accumulate in fat tissue—blubber in seals acts as a reservoir.
When seals remain healthy and fat stores are plentiful, much of the contamination stays sequestered in fat. Problems arise when seals lose weight due to nutritional stress: stored contaminants are mobilized back into the bloodstream and circulate throughout the body.
Remili explains that although the 2011 samples suggested a rebound from malnutrition, future nutritional stress could amplify the long-term damage caused by oxidative stress. In practical terms, when seals burn fat during lean periods, toxins released from fat move into vital organs and the bloodstream, increasing health risks.
Climate change could intensify the danger
Arctic conditions are changing rapidly: sea ice is diminishing faster, ocean temperatures are rising, and food webs are shifting. As ice melts and waters warm, seals may need to travel farther or dive deeper to find food, while altered currents could bring more global pollutants into Arctic waters.
For communities along the Labrador coast, these dynamics raise concerns about jointly facing wildlife health and human health risks. Ringed seals are central to Inuit food systems and cultural continuity, so their well-being is a barometer for the broader region’s resilience.
Brown emphasizes the stakes: healthy seal populations underpin food security and cultural traditions in the North. Protecting Arctic ecosystems will require aggressive climate action and tighter controls on long-lasting pollutants. Ringed seals serve as sentinels of the North, reflecting the health of the waters, ice, and food webs they depend on. When their health falters, the entire Arctic system feels the strain, with consequences that ripple through wildlife, communities, and climate feedbacks.
The study appears in Environmental Research.
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