Polar Bears Are Consuming Less Mercury—But There's a Downside

Ansgar Walk, Wikimedia Commons // CC BY 2.5
Ansgar Walk, Wikimedia Commons // CC BY 2.5

Scientists studying mercury levels in polar bears say that melting sea ice has forced the bears to change their diets. The researchers published their study in the journal Environmental Science & Technology.

Mercury is all around us. Some of it occurs naturally in plants, animals, and the soil. Some of it is our fault, the result of industrial pollution from coal and other fuels.

Regardless of its source, it piles up in living things the same way. Tiny animals eat plants containing mercury, and the mercury stays in their bodies even after all the plant matter is gone. Then those tiny animals are eaten by small animals, and on and on, onward up the food chain. Apex predators like swordfish and sharks are swimming globs of mercury, which is why we tell pregnant women not to eat them.

For the same reason, they shouldn’t eat polar bears, either (although we would kind of like to see them try). Previous tests on bears in the southern Beaufort Sea found alarmingly high mercury levels in the animals’ hair and body tissue—the result of the bears’ diet of mercury-saturated ringed seals. Or their former diet, we should say.

Researchers followed Beaufort Sea bears from 2004 to 2011, taking regular tissue and hair samples from sedated bears and by long-distance biopsy dart. Chemical analysis of the samples showed a clear and steady decline in mercury levels. Each year, the bears’ bodies contained 13 percent less mercury.

But it’s not as though these bears were getting 13 percent smaller. They weren’t wasting away. So what had happened?

It turns out their main prey, ringed seals, had grown scarce. Ringed seals spend most of their time on sea ice. But as the sea ice disappeared, so did they. In response, the bears shifted their predatory attention to bearded seals and bowhead whales, both of which carry less mercury. Even as their mercury levels dropped, the bears' BMI increased, perhaps because they were eating more blubber from the larger prey.

The authors note that the bears in their study might not represent all bears in that region. They could only take samples from the bears they could find along the coast. Less successful hunters might still have been struggling out at sea.

They also say that the polar bears’ prey-switching is, sadly, not a sustainable solution. We’re not exactly experiencing a surplus of whales, here.

Save Up to 80 Percent on Furniture, Home Decor, and Appliances During Wayfair's Way Day 2020 Sale

Wayfair
Wayfair

From September 23 to September 24, customers can get as much as 80 percent off home decor, furniture, WFH essentials, kitchen appliances, and more during the Wayfair's Way Day 2020 sale. Additionally, when you buy a select Samsung appliance during the sale, you'll also get a $200 Wayfair gift card once the product ships. Make sure to see all that the Way Day 2020 sale has to offer. These prices won’t last long, so we've also compiled a list of the best deals for your home below.

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Thailand National Park Officials Mailed Trash Back to Litterbugs

Spiderstock/iStock via Getty Images
Spiderstock/iStock via Getty Images

If hefty fines aren't enough to stop people from littering in Thailand's national parks, officials hope that good, old-fashioned guilt-tripping will do the trick. As The New York Times reports, Khao Yai National Park in central Thailand responded to a recent littering offense by mailing abandoned trash back to the litterbugs who left it there.

The responsible party left behind a tent filled with trash after camping overnight in Khao Yai. In Thailand, littering in a national park is punishable by up to five years in prison and a $16,000 fine. The park officials took a less conventional approach to this particular crime. After cross-referencing equipment rental forms with a discarded prescription bottle, they were able to track down the offenders and mail them their forgotten garbage.

The clear bag of trash came with a note. “You have forgotten some of your belongings at the Khao Yai National Park,” it read. “Please let us return these to you.” Varawut Silpa-archa, Thailand's environment minister, referenced the incident in a Facebook post, writing, “I will pick up every single piece of your trash, pack them well in a box, and mail it to your home as a souvenir." In addition to getting a package of trash in the mail, the unidentified campers have also been banned from staying in the park overnight.

Officials tasked with protecting the environment have seen firsthand the damage litter can cause. Plastics can take centuries to break down, and in that time they pose a serious threat to wildlife. Trash that builds up in places where people seek refuge can also be bad for their mental health. A 2015 study found that seeing litter on a beach counters the restorative qualities of being in nature.

[h/t The New York Times]