Environmental pollution from three continents finds its way to the Arctic – and into the animals that live there.
The year is 2030, and polar bear number N 23450, tagged by Norwegian researchers back in 2015 in Svalbard when she was a cub, is starving. It’s not just that the summer arctic ice cover has mainly disappeared due to global warming, and with it her ability to use the ice as a platform to hunt ringed seals, her preferred food.
No, N 23450’s ancestors from 6000 years ago were able to survive a prolonged warm period with little arctic ice – they were clever enough to find other ways to hunt. N23450 has other problems.
The toxic chemicals that have wafted up from western Europe, Russia and North America over the decades and that have accumulated in her body have laid waste to N23450’s immune system and befuddled her hormones. As a result, she’s sick and confused, and can’t think well enough to find new ways to feed herself. When N 23450 finally dies of starvation at the end of the summer of 2030, it won’t be because there wasn’t enough food to eat.
The Arctic may be the dirtiest clean place on Earth. Only a few smokestacks foul its frigid air, and just a handful of industrial plants discharge pollutants to its rivers and seas. Yet the 2500 or so polar bears that wander the remote Norwegian archipelago of Svalbard, only 1000 km from the North Pole, have some of the highest levels of toxic organic pollutants of any creature walking the planet.
And the glaucous gulls that wheel and cry over the vertical cliffs of Bear Island, an important nesting area midway between Svalbard and continental Norway, carry the fingerprint of mercury contamination (in addition to organic pollutants) in their muscle and livers.
Scientists postulated 25 years ago that pollutants such as DDT and mercury could ride the winds from the industrial south and accumulate in arctic environments, potentially harming the wildlife – and the people – that call the region home. But much about how these pollutants find their way into living beings, and the effects that the contamination has on the ability of arctic species to survive and reproduce remain a challenging riddle, especially in view of global warming.
Researchers at the Norwegian University of Science and Technology (NTNU) are now work-ing with two projects that approach this complex riddle from different directions. Both efforts are linked to the International Polar Year, a massive cooperative research programme among 60 nations to further our understanding of the polar realms.
Can polar bears cope with the combination of climate change and environmental pollution?
NTNU scientists working with the “Bear Health” project are looking at how the combined stresses of toxic pollution and climate change will affect polar bear health. COPOL, or “Contaminants in Polar Regions”, takes a different perspective. By examining the uptake and transfer of contaminants in food webs – from the tiniest zooplankton to animals near the top of the food chain, such as black-legged kittiwakes and ringed seals – it will study how contaminants accumulate, and estimate how global warming will change things in the future.
The double whammy
PhD candidate Jenny Bytingsvik studied pollutants in Atlantic cod as a master’s student at NTNU. In joining the Bear Health project, the 32-year-oldresearcher is tackling a different species in a much more critical situation. As she sees it, the central question of the Bear Health project is whether polar bears can survive the vagaries of climate change, given all the other problems their environment poses.
It’s a question many have asked, particularly as pictures of polar bears desperately swimming in search of an ice floe to rest on have circulated on the Internet. If you’re a polar bear, the fundamental problem posed by climate change is that it will reduce the amount of sea ice you need to hunt for your preferred food, ringed seals, or to find mates.
But paleoclimatologists, scientists who piece together environmental and geological clues to reconstruct the Earth’s past climates, know that polar bears have survived in much warmer conditions – the Norwegian Polar Institute has conducted research that suggests August sea surface temperatures in the North Atlantic were as much as 5 degrees C warmer than today as recently as between 6000-9500 years ago.
There’s one problem with this, Bytingsvik is quick to point out: the last warm period for
polar bears was before we started pumping out industrial chemicals such as PCBs and DDT. These pollutants don’t break down easily, which is why they are called persistent organic pollutants, often abbreviated as POPs.
They are readily accumulated in the fats of polar bears, and affect the bears by altering their vitamin status, weakening their immune systems, affecting nervous system development or by changing hormonal signaling that may have an effect on growth, development and reproductive behaviour, she says. “Can bears handle this combination of climate change and environmental pollution?” she asks.
Cubs in trouble
Most troubling is the in-sidious way that POPs can affect polar bear cubs. Because POPs are easily absorbed by fats, polar bear milk is loaded with the harmful chemicals. As a result, cubs typically have higher levels of POPs in their blood than adults. These pollutants can certainly affect the cubs’ developing nervous systems, Bytingsvik knows, but the critical question is how.
“Will it affect their cognitive development and/or behaviour?” she asks. “or will pollutants eventually weaken the ability of bears to adapt to climate change?”
Bytingsvik and her supervisor, NTNU Professor Bjørn Munro Jenssen, have begun to assemble the information to find the answers. Starting in 2007, Bytingsvik began collecting blood samples from Svalbard polar bears, in association with the other cooperating research institutes in the Bear Health project.
The groups collected samples from 120 animals in their first two field seasons; those samples are now being analysed for a range of contaminants and associated vitamin and hormone levels. Thyroid hormones, for example, play a role in nervous system development and learning, while sex hormones naturally play a role in reproduction. It’s already known that high levels of POPs negatively affect polar bear hormone levels and their immune status. The Bear Health project will try to determine just how much more of a stress climate change will pose.
A natural laboratory
Climate change will not just make the planet warmer. In Svalbard, a shift in winds and ocean currents will change the source of the ocean water that flows in and out of the archipelago’s many fjords.
Scientists know this because it already happens: fjords on the western side of Spitsbergen now have a much stronger inflow of water coming from the Atlantic Ocean. Not surprisingly, any winds and waters coming from the industrial south are loaded with pollutants, while arctic sources are typically less laden.
This change in water flow provides COPOL researchers with a natural laboratory and a crystal ball all rolled into one: by studying the types of creatures in the fjords and linking them to the different seawater sources, scientists can get a sense of Svalbard’s future in a warmer world.
Perhaps a warmer planet will cause ocean currents to shift and wash more pollutants to the Arctic. Or perhaps warmer temperatures will increase the rate at which arctic creatures uptake toxic substances.
“You need to understand how all these things contribute to the big picture,” says Geir Wing Gabrielsen, one of Øverjordet’s supervisors and a researcher at the Norwegian Polar Institute who is also in charge of the Norwegian arm of COPOL. “We want to look at the combined effect, but it is a huge research challenge.”
Big blooms and mercury uptake
An NTNU PhD candidate, Ida Beathe Øverjordet, is working on a piece of the COPOL project that involves tracking mercury throughout the arctic food chain. In the summer of 2008 and 2009, she and the members of COPOL research team, which includes representatives from five Norwegian research groups along with NTNU, travelled by a ship to Kongsfjorden, on Svalbard’s western side, where they sampled everything from sediments, phytoplankton and fish to different bird species.
Among the key creatures of interest are species of the zooplankton genus called Calanus – a being that has a special link to Trondheim, because it was first described in 1770 by the city’s Bishop Gunnerus, who was also a practicing scientist. Calanus is one reason arctic waters can be so productive – the zooplankton themselves are enormously abundant, and are eaten by everything from polar cod to little auks.
The arctic species Calanus glacialis feeds on algae, which in arctic waters can only grow when the sun returns. By early May, the algae have bloomed, and the Calanus population has exploded after its algal feast. “It was amazing,” Øverjordet said of sampling the species, which can be as large as a sesame seed. “There were literally a million of them in the nets.”
But the Calanus population explosion also occurs concurrently with another, less well-known arctic phenomenon involving mercury deposition. Essentially, the gaseous form of mercury, which wafts out of power plant smokestacks and is carried north on the wind, undergoes a chemical transformation as a result of the arctic sunrise.
The mercury gas takes on a form that attaches readily to dust particles, which in turn accumulate in snow and can be washed out to sea when the snow melts. This process has only just been described in the last decade. Partly as a result of research by one of Øverjordet’s supervisors at NTNU, Torunn Berg, a professor in the chemistry department.
“That huge deposition in the spring might happen just when the algae bloom happens,” she says.
“That’s one of my hypotheses – and then the plankton eat the algae, and that’s how mercury gets into the food chain.”
Øverjordet is working closely with another one of Berg’s PhD candidates, Anne O. Steen, to figure out exactly what happens to the mercury that rains out of the arctic skies after the polar sunrise.
Samples taken for COPOL will also be checked for new substances, such as siloxane, which is used in everything from an antifoaming agent in the oil used to fry McDonald’s french fries, to additives in cosmetics and shampoos. If researchers find siloxane, which can have harmful reproductive and carcinogenic effects, they will know that it is capable of being transported long distances and can accumulate in arctic species.
Of the roughly 90,000 chemicals that are used by society today, approximately 4,000 are considered toxic or harmful to the environment. Gabrielsen says it’s important to pursue issues like these, which can be discovered as a part of COPOL. “If a substance like this is transported and is accumulating in animals, we need to know if it is having an effect,” he says.
But there’s more: if new and changing chemicals can accumulate in polar bears, they can accumulate in humans, too, he cautions. Polar bears can be like “a canary in a coal mine”, he says. “The Arctic is a really good indicator of how these changes will affect us.”