Cyanobacteria survival on   Mt. Erebus

The Long, Sweltering Night

The southernmost active volcano in the world, Mt. Erebus, Antarctica, has multiple sites around the summit with geothermally heated soils. The largest of these sites, Tramway Ridge, has hot, steaming soil with temperatures up to 65C (150F). At this site, you can find many sections of soil that are covered by large mats of Cyanobacteria (photosynthetic bacteria). But what happens to these Cyanobacteria when their livelihood (sunlight) disappears for 4 months every winter in the polar night?

Most Cyanobacteria in other parts of Antarctica simply go dormant over winter, using cold temperatures to enter a state of frozen stasis. However, this is not a possibility for the Cyanobacteria living at Tramway Ridge on Mt. Erebus, since the soils they inhabit remain hot even during winter. So how do they survive the winter darkness?

At the end of 2024, I received a Marsden Fast-Start research grant to attempt to answer this question using a combination of laboratory and field experiments. We will be using Cyanobacterial isolates from Tramway Ridge to perform winter darkness simulations in the lab, testing for potential survival strategies such as facultative mixotrophy (switching to heterotrophy, i.e. consuming carbon from the environment for energy, in the darkness) or storage (detecting the oncoming winter and storing up nutrients to survive). Additionally, we will be performing shading experiments at Tramway Ridge, placing small covers over sections of mat for several months and looking at the response of both the resident Cyanobacteria and the broader microbial community to the darkness.