Don’t worry; glaciers get acne too.
When seen from high above, small blemishes dot Antarctic glaciers. Like acne, they come and go. And like acne, they’re full of tiny bacteria.
A team of CU Boulder researchers leaves for Antarctica’s Taylor Valley in October to investigate exactly what these pockmarks, called cryoconite holes, could teach us about microbial life in extreme environments — and in our own bodies.
“No one’s ever really documented the microbes that live in these sorts of ecosystems,” Steve Schmidt, professor of ecology and evolutionary biology, said to a group of CU Boulder students.
The ingredients for glacier acne are simple: wind, sun, ice and dirt. And the recipe is pretty easy too: sediment blows from the ice-free valley floor and onto the glaciers flowing down over steep mountain slopes. The dark dirt heats up faster than surrounding ice and melts into pits of varying size. Over time, vibrant mats of this wind-blown sediment layer the bottom of the holes.
Microscopic organisms blow in with the dust, creating an infinitesimal ecosystem at the bottom of each hole. These biomes are active during the warmer months of the austral summer, and also manage to survive the harsh Antarctic winters in states of suspended animation.
Cryoconite holes pepper about 10 to 15 percent of Antarctic glaciers, but they aren’t isolated to the deep, cold south. They sprinkle the glaciers of the high Himalaya and Alaska, freckle the ice sheets of Greenland and stud other frozen environments around the world.
The team decided to study cryoconite holes in Antarctica instead of in more easy-to-access locales like Montana or Alaska due to the Antarctic’s relative purity. The area has seen little direct human impact or development, post-doctoral researcher Pacifica Sommers said.
“It’s an unusual place of incredible beauty,” Research Associate Dorota Porazinska said.
Each hole preserves a petri dish of tiny life — including nematodes, tardigrades (or water bears) and rotifers. Through a microscope, they look like miniscule peas, squiggles and apostrophes.
These diminutive life forms are notoriously difficult to culture in a laboratory environment. The microbial ecosystem of even a patch of soil houses a dazzling diversity of life.
The wind-blown pimples of Antarctica offer a natural laboratory teeming with enough life to stimulate scientific inquiry, Schmidt said. But the frigid environment limits what can survive inside so that scientists aren’t overwhelmed by data. The ice even creates its own lids.
“So if we’re sitting here thinking, ‘If only we could do these kinds of test-tube experiments somewhere with evolutionary history,’ there’s a place down in Antarctica where these types of ecosystems might actually exist,” Sommers said.
The researchers will drill cylinders of ice from the cryoconite holes, and examine the layers of dirt at the bottom. Called “sediment patties” — and not entirely unlike burger patties — thick glops of Antarctic muck stick to the bottom of the cores.
In these patties, layers of dirt represent years of wind-blown dirt and life. The layers come in a variety of colors — red, orange, green and black. The researchers will test how the order of these colorful layers affects the overall ecosystem of the holes.
These layers represent a simplified model of the critters that live in human guts and other microbial ecosystems.
“We’re thinking about things like wetlands or re-vegetating old mining sites,” Sommers said. “You might get radically different communities where a beaver showed up and built a dam versus where it didn’t. Same thing might happen in your gut if some microbes start exuding waste products that are more important than others.”
The team will also create its own holes on the ice sheets of Antarctica. In some they’ll put, say, an orange layer of sediment before a black layer. In others, they’ll put a black layer before the orange. Then, they’ll test for similarities and differences in the holes’ overall microbial makeups.
Sommers said that these tests of “priority effect” might eventually inform procedures such as fecal transplants and the scientific understanding of the ecosystems of the human gut. This potential, she said, comes from the mysterious world of microbes.
Microbes run the planet unseen, Schmidt said. These tiny bacteria govern our guts and our gums, the oxygen we breathe, the soil on which we tread, the plants and animals and metabolic processes around us.
“As an aggregate, they’re more metabolically complex than you or me or anything else,” Jack Darcy, a Ph.D. student in ecology and evolutionary biology, said, “ They actually do more things than we do, and they’re responsible for everything from the tiny scale to the large scale.”
Darcy stressed that these studies represent only the first steps on a long road of microbial discovery. However, it could provide a means of building theory that illuminates much more than the Antarctic ice.
“You turn up the complexity a bit and change the tool a little bit, and turn up the complexity a little more, and eventually we’re at a stage where the tool works in a complicated system,” he said.
A system, perhaps, as complicated as the human gut.
“It’s really hard to drill cores in someone’s butt,” Darcy said. “But it’s comparatively easier to go down to Antarctica and drill holes in a glacier.”