Cryoconite is a fancy word for dirt on a glacier. Because of its dark color, the dirt absorbs heat from the sun and melts into a little puddle, which is then a cryoconite hole. Bacteria and other microcsopic organisms can live and reproduce in these small, ice-bound microcosms. The especially cool feature of Antarctic cryoconite holes (compared to, say, Alaskan cryo holes) is that an ice lid often forms over them, isolating them from the rest of the atmosphere. They can persist that way for many years. The holes melt internally each summer, and during very warm summers the ice lid may even melt, creating an open ecosystem that can allow immigration from nearby holes or new cryoconite blown onto the glacier. For more detail, see our post on how cryo holes form.
What are we studying them for?
Scientists understand some basics of how biological communities, like human microbiomes, are organized, but many details remain unknown. For example, what determines how many species live in one person’s gut? Or which species live there? How important is the arrival order of different microbes, or the diversity of the first communities to arrive?
While these questions can be studied in test tubes, it is hard to culture many microbes outside their natural environment and so our answers may be incomplete. However, it would be potentially unethical and logistically difficult to study these processes in live humans.
Cryoconite holes are a sort of “Goldilocks” experimental system: complex enough, but not too complex. We are studying microbial communities in their natural environment, avoiding the artificiality of test tubes, but they are much simpler than many soil or human microbial systems.
Over the course of three field seasons, we are be sampling natural cryoconite holes and building our own cryo holes to ask a few very specific questions, including:
- Which environmental factors are associated with diverse or productive ecosystems in cryo holes?
- How much does the diversity of the first community to arrive affect diversity and production?
- How much does it matter which species arrive first?
2016-2017 was our first season, in which we sampled the natural cryoconite holes. We set up our major experiments, in which we made our own cryo holes to control which microbes arrive when, during 2017-2018. We are re-sampling those experimental cryoconite holes currently during the 2018-2019 season.
So far, we have discovered that the source of cryoconite (the streams and soils surrounding the glaciers) seem important to the diversity and productivity of the cryoconite holes: the more diversity and productivity arrives in the hole, the more is present. Regional factors that determine diversity and productivity of microbes across the landscape have a large effect on the holes. We have also discovered that the cryoconite holes are like islands, with larger holes having more species than smaller holes.
We are studying cryoconite holes in the Taylor Valley, one of the McMurdo Dry Valleys. This is part of the very small (<1%) area of Antarctica not covered in ice. Our experiment takes place on Canada Glacier, next to Lake Hoare. We stay in the field camp there and hike an hour up onto the glacier every day.
To get to the Dry Valleys, we fly from the US to New Zealand (a 13 hour flight from Los Angeles), then take a plane from Christchurch, New Zealand, to McMurdo Station in Antarctica. That means a 5 hour flight in a C-17 jet, or a 10 hour flight in a C-130 prop plane, sometimes equipped with the skis that must be used during much of the summer season, when the ice runways are too soft to use the larger wheeled aircraft.
Do we ever see penguins? We sometimes see isolated penguins near McMurdo Station, but their main rookeries are too far away to see easily. Sometimes lost penguins wander up Taylor Valley past our field camp, too.
Do we ever see polar bears? Nope, they live in the Arctic, not the Antarctic. We see lots of seals at ice holes, and sometimes as we fly in a helicopter between McMurdo and Taylor Valley, we go over the edge of the sea ice and see killer whales swimming along it.
Is it cold? Compared to most of the US, definitely! But we are there during summer (Nov-Jan), so it NEVER gets dark – we don’t even need to bring flashlights for camping. In fact, since it is winter in North America at that time, we had many days in our 2016-17 season that were warmer than the Midwest was that day, and even some days where it was warmer than Colorado.
How do we get around between glaciers? We either hike or hitch a ride in a helicopter.
What other questions do YOU have? Post them on this blog, or email us at cryoholes[at]gmail.com.