Frozen Waves in Volcanic Desert
Frozen Lake Bonney is where we are seeking protists (single-celled life with traits related to animals or plants). At either side rise the mountains of Taylor Valley. During summer, streams flow down the mountainsides from melting glaciers. The rest of the year, the water sits there, freezing and subliming, shaping unique contorted forms that persist throughout the year. The cracked and frozen surface looks forbidding, but with “stable-icers” on your boots, it’s easy to walk across.
Different parts of the lake show different unique ice features (hat for scale). This patch of ice looks like cracked-open styrofoam, with many pockmarks tinged with volcanic dust. The dust is dark, so where it settles it absorbs light and heats the water, melting a little hole, which then collects dust and melts more. But the holes remain small, whereas the ice is nearly 4 meters thick.
Our field team is studying microbial photosynthesis. The photosynthetic microbes grow in water beneath the ice, using light that filters through. There are many different species of phototroph (organisms that conduct photosynthesis). Rachel’s team has isolated two unique species, one a green primary alga Chlamydomonas that grows only with light; and an Isochrysis, called a “secondary alga” because it evolved as a food-eating protest than engulfed a green primary alga. Isochrysis can grow without light by eating food such as the remains of other protists.
Isolated species of protists can be cultured within the lake environment, through a hole drilled and melted through the ice (Rachael’s blog).
Rachel is culturing the two kinds of phototrophs together, in the lake environment, within dialysis tubes that permit nutrients and minerals from the lake to reach the trapped microbes. The idea is to show which grow better, at which depth in the lake. We predict the Chlamydomonas grows best near the surface, whereas the Isochrysis does best at the mid-level depth (15 meters). You can see how green the cultures look, with all their chlorophyll.
Here, grad student Chris Sedlacek adjusts the sample holder. Chris is a very kind, helpful Canadian from Rachael’s lab. A great team-mate for Rachael and Wei.
Besides Rachael’s team, there are two or three other teams coming and going at various times. We all use the same camp facilities and take turns cooking and cleaning. More on the camp, and the lab analysis, to come. And a riddle: How is our camp like my Cuba tour, two years ago?