In late 2016, a team of microbiologists and ecologists will spend weeks camped in one of driest, coldest places on Earth. Their goal is to study aquatic microbes in the Dry Valleys of Antarctica, a landscape that rarely warms above freezing, even in the summer. What could they hope to discover? “Some ecological general principles people have been trying to untangle for decades…,” according to Dorota Porazinska, a research associate on the team from the University of Colorado Boulder.
The focus of their research are small pits in the ice–called cryocronite holes–about the diameter of a hamburger and a foot deep (though sizes can vary). The holes are filled with meltwater or ice, depending on the season, and at the bottom is a “patty” of microbes–bacteria and microscopic animals.
This is why the team of ecology researchers from Colorado is headed to Antarctica. Understanding the basic principles that drive ecological systems is crucial for a wide range of situations, such as combating invasive species, reclaiming a strip mine, or even treating a runaway bacterial infection in your gut. (Yes, the bacteria in your intestines form their very own ecosystem.)
But trying to understand an ecological system as complex as a forest or the human intestines is a daunting task. Researchers have begun to tackle these questions by studying the interactions of two or three bacteria species in a test tube, but such a simplified system can only reveal so much.
In the cryocronite holes of Antarctica, the CU team hopes to find a next step: a real-world ecosystem that has evolved naturally, but still simple enough to study in detail. “These cryocronite holes are this great Goldilox system,” said Pacifica Sommers, a post-doctoral researcher on the team. “We can actually study this microbial system. We can study whole worlds, whole continents in these little, tiny holes and see the great, big effects.”
On the glaciers of the Dry Valleys, Sommers, Porazinska and the rest of the team will drill and extract ice cores from cryocronite holes. Back in a lab, they will use DNA sequencing to identify the species that live in each hole.
Over three years and three Antarctic expeditions, the CU team hopes to conduct an extensive survey of cryocronite holes. By comparing the number of species found in different holes, as well as variations in the amount of nutrients and chemistry, the team hopes to better understand the principles that govern these tiny microcosms.
They’re also going to make some of their own holes by placing clumps of microbes on the glacier's surface, varying the type and amount of microbes they use. While no one has ever before tried to create cryocronite holes for a controlled experiment, the team hopes the cryocronite community is simple enough that they’ll be able to understand how different starting conditions can shape the growth of a hole’s ecosystem.
“The very cool part about these holes is they are their own independent ecosystems,” said Porazinska. “We are using this simplified ecological system to try to address some of these questions.”
For example, will a hole that starts with a very small number of bacteria of a certain species evolve in the same way as a hole that starts with a larger, more diverse group of bacteria of the same species?
It’s a question that goes far beyond icy holes in Antarctica. The bacterium Clostridium difficile often infects the intestines of medical patients who have been taking antibiotics (which disrupt the natural ecology of the bacteria in their guts). One treatment for a C. difficile infection is to transplant fecal matter from a healthy person into the gut of the infected patient, reintroducing the natural bacteria to the patient’s gut. But how much fecal matter needs to be transplanted into the patient to kickstart a new, healthy population?
“In general these are the kind of the big questions in a lot of ecological systems, so getting a better sense of how communities operate generally will help us understand how your community in your gut might operate,” said Sommers. And an icy hole on an Antarctic glacier may be the best place to start.