Above: The Baffin Island community of Pond Inlet, in Nunavut (Image © RyersonClark, iStock)
When you think of the Canadian Arctic, what comes to mind? If you’ve never been there, you might think of polar bears (nanuq in Inuktitut), seals (nattiq), cold and snow. If you’ve visited the Arctic, or if you live there, you might also think of Arctic char (iqaluk), caribou (tuktu), beautiful tundra and amazing views of the northern lights (Aqsarniit).
When you think of southern Canada, big cities and urban landscapes might come to mind. A completely different world! But the pollution produced in the southern cities can travel long distances through the air, all the way to the Arctic. There, it can impact aquatic food webs, and all the species who depend on them—including humans.
Did you know? Bioaccumulation occurs in an individual animal or plant. Biomagnification that occurs within a food web or ecosystem.
Mercury in food webs: Bioaccumulation and biomagnification
Many types of chemical contaminants end up in freshwater and saltwater ecosystems. Mercury is one that scientists have studied a lot.
Mercury pollution can come from various sources, including making cement and burning coal. Mercury particles can travel long distances in air masses, and when these air masses reach colder temperatures in the Arctic, the air condenses. Rain, snow and other types of precipitation deposit mercury on land and in bodies of water.
When mercury enters a body of water—like a stream, a lake or an ocean—it can make its way through the food chain. First, mercury reaches plants. Next, it goes to insects, small fish and other animals that eat these plants. Then, it goes to carnivorous species, like bigger fish that eat these herbivores. The fish can’t get rid of this mercury, and it builds up in their fatty tissues over their lifetime. This process is called bioaccumulation. It can occur with other metals, too.
But it doesn’t end there. These fish become food for other species, like birds, mammals and even bigger fish. When these animals eat contaminated fish, mercury builds up in their fatty tissues, too. Further up the food web, animals eat more and more contaminated prey—and get higher and higher doses of mercury. This is called biomagnification, and it’s a very big problem for the top predators in an ecosystem.
Did you know? People who eat a lot of fish are at risk for mercury poisoning. Symptoms include trembling, vision problems and other neurological problems.
Mercury in the Arctic
Bioaccumulation and biomagnification of mercury occur in food webs everywhere. However, they’re an especially big problem in Arctic food webs.
Mammals in the Arctic have layers of blubber to help them survive the cold temperatures. Remember, mercury bioaccumulates in fatty tissues. This is bad for the animals because mercury can cause problems for their development and reproduction.
But it’s also bad for the people of the Arctic who eat these mammals. That’s because mercury can also cause serious health problems in humans. It can hurt the brain, spinal cord, kidneys, liver and developing fetuses.
The Arctic has a large Inuit population. A traditional Inuit diet includes lots of fish, especially Arctic char, and other country foods like walrus, seal and beluga. Country foods have nutritional benefits. Finding a balance between getting these benefits and avoiding the potential harm of contaminants like mercury is a real challenge!
Did you know? When pregnant women eat food contaminated with mercury, it can affect the brain development of the fetus. Studies show this can lead to developmental and learning disabilities after birth.
As you can see, eating certain types of animals can be risky for people living in the Arctic. That’s why governments test mercury levels in various species and issue recommendations on which ones are safe for humans to eat. For instance, the governments of the Yukon and Northwest Territories recommend that people eat fish on lower levels of the food web. These fish have not absorbed as many contaminants as larger predatory fish.
Even if you do not live in the Arctic, keep an eye on these recommendations if you eat a lot of fish.
Did you know? The government of Nunavut recommends against pregnant women eating ringed seal liver. Although it’s a delicacy, it contains very high levels of mercury.
How the rest of Canada can protect the Arctic
Want to reduce your impact on food in the Arctic, no matter where you live? Properly dispose of items that contain contaminants! Many local governments and companies have programs to help people do this safely.
For example, compact fluorescent (CFL) light bulbs contain small amounts of mercury. Don’t throw them into the garbage! Instead, bring them to a local hardware store or waste drop-off centre.
With small steps like these, you can help keep contaminants like mercury out of the Arctic!
About mercury and living organisms: