Who lives in cryoconite holes?

Not hobbits, that’s for sure. In fact, a cryoconite hole is about as far from a hobbit hole as you can imagine.

Hobbit hole Cryoconite hole
Found in Middle Earth Found at the ends of the earth
Not nasty, dirty, or wet Definitely nasty, dirty, and wet
Comfortable Cold
Full pantry Very low nutrient environment
Round front door with brass knob Round ice lid that sometimes melts
Residents typically do not travel Residents rely on travelling


A cryoconite hole is a small pothole that forms in a glacier when some dark dust (“cryoconite”) absorbs the sun’s energy and melts the ice around it. You can see a diagram of this process here and photos of these holes here.

Some extreme organisms live in these cryoconite holes. They include bacteria, fungi, and microscopic ciliated protists, bdelloid rotifers, and the famous tardigrades (“water bears”). In order to thrive in the only occasionally hospitable puddles, these organisms must all regularly tolerate freezing, drying out, and being blown around to new holes. The cryoconite holes in Antarctica in particular are interesting ecosystems, as they will often keep a frozen ice lid even while melting out in the middle, isolating it from the atmosphere. What if they use up all their oxygen? Or all their carbon dioxide?

A few papers have been published on the residents of these cryoconite holes. A perhaps surprising amount of diversity exist in these holes for their extreme nature. I must have a little Took in me, because I am excited to travel to Antarctica myself to find out how this diversity of organisms persists. In the meantime, I am fortunate to have collaborators interested in finding out exactly who is living in samples they have brought back from previous work there.

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