Microbiology of Mt. Erebus

Antarctica, best known for its extreme cold and glaciers, harbors a few active geothermal sites. The largest of these is Mt. Erebus, located on Ross Island. Mt. Erebus (3,800 meters tall; 12,500 ft) is the southernmost active volcano in the world and houses an active lava lake in the middle of its Main Crater. This same lava lake also produces daily strombolian eruptions. There are a variety of geothermally active sites across the summit of Mt. Erebus, in addition to the lava lake, which are generally concentrated in a few large sites. The hot soil and steam from the volcanic activity at these sites collides with the extremely cold air around Mt. Erebus (never warmer than -20C in the summer), resulting in a variety of magnificent features, such as ice towers, ice caves, and ice hummocks. Mt. Erebus is also a phonolitic volcano, which gives the summit a geochemical composition only found on a few other volcanoes. It also experiences prolonged periods (3+ months) of complete darkness every year during the winter.

What sorts of microorganisms inhabit this extraordinarily harsh environment? How do these microorganisms make a living? Have the isolated and unique geochemical nature of Mt. Erebus led to endemic microorganisms on Mt. Erebus? Do the microbes living there possess novel metabolisms? These are the sorts of questions that we are attempting to answer in the MAGMA Project (Multidisciplinary Analysis of Geothermal Microbes in Antarctica), of which I am the lead postdoc.

Read more about the MAGMA Project and follow along with our fieldwork on our Facebook page.

The first samples from the MAGMA project were collected in 2019 by several members of the team from two geothermal sites on the summit of Mt. Erebus: Tramway Ridge, a relatively sheltered site with hot soil and lots of active fumaroles and moss mats; and Western Crater, a very exposed site with hot soil covered by ice hummocks and no moss mats. We analyzed the microbial communities at the two sites and found them to be starkly different, with Tramway Ridge having much more archaeal species (known for metabolizing ammonia, a nitrogen-containing compound) than Western Crater, among other differences. Although the sample sets we analyzed were collected along temperature gradients (from ~60C down to ~20 C), pH, not temperature, was the primary soil chemistry factor that influenced the composition of the microbes living there. This was because Tramway Ridge had a significantly lower pH (~4-6) than Western Crater (~7-9). This research was published in 2022 (https://doi.org/10.3389/fmicb.2022.836943).

Comparison of the microbial community across temperature gradients at two sites on Mt. Erebus: Tramway Ridge (TR) and Western Crater (WC), showing the higher proportion of archaea at TR and higher proportion of unknown microbes at WC. Two transects were collected at TR. Figure 4 from Noell et al., 2022.

This most recent season (November 2023), our team conducted two drilling operations at geothermally heated soils on Mt. Erebus, with the goal of culturing some of the very unique and potentially endemic microorganisms that inhabit these remote and difficult-to-access sites.