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By studying beetles, researchers find they have a domino effect on much larger species as the Arctic warms.
Arctic climate change bugs McGill University scientist Chris Buddle...
While much of the climate science community studies big things—sea ice thickness or atmospheric carbon dioxide concentrations—Buddle, an insect ecologist, focuses on the opposite end of the spectrum. He studies beetles that commonly inhabit the northern latitudes, and despite their tiny size, they are a cornerstone of the Arctic ecosystem.
In an exhaustive study published in PLOS ONE, Buddle and his study partner, Crystal Ernst, and a team of researchers spent two years cataloging 460 different species of Arctic beetles in 12 locations, ranging from the edge of the boreal forest in northern Ontario to Ellesmere Island in the far North. They determined where the beetles are, how many there are, and how they interact with other insects, plants and animals, to establish their roles in ecosystems.
The study provides the first-ever baseline data for measuring how global carbon emissions and the rise in Arctic temperatures are affecting beetle populations, and by extension Arctic biodiversity—with implications for ecosystems worldwide. The project relied on a sampling method that could be repeated in all of the Arctic habitats.
Already the results, combined with anecdotal evidence from scientists, suggest a troubling trend, according to Buddle. The insects are slowly beginning to migrate into new habitats, and there is a strong suggestion that climate change is responsible. One of the most tangible discoveries from the data is a shift northward by some of the beetles, suggesting they are migrating to regions where colder temperatures are most favorable to their survival.
"Insects are very sensitive to environmental change," Buddle said. "This study will provide the foundation of how climate change will affect these beetles...to complete the whole story on how climate change will affect the Arctic as a whole."
Beetles are especially sensitive to climatic changes because they are cold-blooded and their body temperatures fluctuate with changes in their environment. So any global warming-fueled changes occurring in the plants, animals and soil on which beetles depend are "quickly reflected in changes in the beetle communities," Buddle said.
This, and the fact that any disruption to beetles goes on to affect the ecosystem, makes them ideal markers for understanding global warming impacts. Beetles are responsible for 18 activities such as eating other bugs, churning over soil and providing protein snacks for other creatures that help balance the Arctic environment.
A change in the habitat of the beetles offers a warning of the consequences of climate change in the same way as melting glaciers, the shrinking home of polar bears, and shifts in tree lines.
"We think of climate change in terms of cause and effect," Buddle said. "So if [beetle] populations change functional roles related to temperature changes, there is a range of things that change across the ecological function as well." That means what happens to the little bugs has a domino effect that could upset the balance of nature, and go as far as to touch the lives of the people who inhabit the northern reaches.
Buddle uses as an example lung worm infections in musk ox, large Arctic mammals that are an essential source of food and fur for the native Inuits.
Arctic beetles have a taste for snails infected with a parasite that causes the disease, Buddle said. If rising temperatures force the beetles out, it could increase the death rate of the musk ox, he said.
Some beetles are also predators and if the population changes, there will be an effect on the beetles' prey, he said. The beetles that are herbivores will have an impact on plant life.
"These changes means that the natural balance goes out of sync," he said.
A similar lesson can be seen playing out in dramatic fashion with polar bears. Buddle said the consequences of climate change on polar bears—including loss of sea ice habitat and reduced access to food—can be taken as a warning to other species.
"One way to think about the polar bear story is the loss of habitat—not having habitat where they expect it," he said. "You can think of beetles and other species in the same way; that they are losing their habitat and having to shift and move because of climate change."
Buddle calls beetles with heavyweight scientific names like Amara alpine and Pterostichus caribou just plain "critters."
They don't stir visceral emotions like emaciated polar bears or before-and-after pictures of receding glaciers do, he said. But they are far from trivial.
"We need to have a good sense of what is happening with all species," Buddle said. "Beetles tell us in their special way how parts of the biosystem are changing because of climate change."