Part of this year's objectives was to sample cryoconite holes on the Upper Wright Glacier. They are vertical water-filled holes in the gaciers that are up to ca. 1 m in diameter and up to ca. 60 cm deep. At the bottom of these holes there is always a layer of sediment or small rocks, and many of these cryoconite holes have an ice lid. These cryoconite holes are formed by wind-blown dust and small rocks that melt into the ice. Some of our aims are to characterise the microorganisms living in these ice-entombed habitats and evaluate the relationships to microbial communities in other aquatic ecosystems in Antarctica.
Upper Wright Glacier and the large ice fall that is coming down from the polar plateau
Stunning geological strata
Hunting for croconite holes on Upper Wright Glacier
Ian and Hannah are drilling into a cryoconite hole
Most of the cyanobacterial mats that we have found were orange pigmented and the macroscopic structure was flaky to cohesive. The orange colour is due to carotenoids which are an protection against UV and oxidative stress.
I had a small light micrscope with me in the field and the genus Leptolyngbya dominated the orange mats. Leptolyngbya are filamentous non-branching cyanobacteria belonging to the order Oscillatoriales. They are mostly between 0.5-3 micrometre thick. However, the lower side of the orange layers sometimes had green pigmentation, which besides the Leptolyngbya also had some Phormidium. The genus Phormidium also belong to the order Oscillatoriales, but they are thicker with a width of around 5 micrometres.
Flaky orange-pigmented cyanobacterial mats dominated by Leptolyngbya
Cohesive orange-pigmented cyanobacterial mats
green lower side of cyanobacterial mat with Phormidium
Interestingly, we also found some cyanobacterial mats which were dark purple to black. This colour is due to the UV-screening Scytonemin. We found the genus Schizothrix sp. (Oscillatoriales) in the mats which is known to produce Scytonemin. We also found several ponds with large accumulations of the genus Nostoc, which belongs to the order Nostocales and has specialist cells called heterocysts for nitrogen-fixation.
Cyanobacterial mats with the Scytonemin-producing genus Schizothrix
Nostoc accumulations in a meltwater pond
We also found a few ponds with green algae. Green algae biofilms are easy to distinguish from cyanobacteria as green algae are very bright green.
The Wright Valley is one of the ice-free Dry Valleys. The Upper Wright valley is characterised by the so-called Labyrinth, which is an area of steep-sided canyons and channels. It is mainly dolerite and most rocks are bright red. Based on the literature it was formed by large 'floods during the mid-Miocene era'.
In the area you can find many strangely shaped rocks. They are called ventifacts, and are wind- and dirt-sculpted rocks.
Ventifacts in the Labyrinth
Wherever you look you only see rocks and it often reminded me of images showing how it may look on Mars.
Landscapes like on Mars
However, there is life. On one of our walks, we found these lichens. They were on the top of one of the ridges, where the overall humidity seems to be higher due to its location at a height of greater than 750 metres, and the greater influence of clouds and fog. Many of the lichens grow under or in cracks of the rocks, and this enhances the erosion of the rocks.
Lichens on rocks in the Labyrinth
AND, as soon as you get running water and temporary ponds you get thick accumulations of orange-pigmented mats. To date there have only been few morphological descriptions and there is no DNA-based data available at all.
Meltwater ponds covered by ice with bright orange mats
Two-days ago we went for walk to the pressure ridges in the evening. The pressure ridges are forming where the ice shelf and sea ice are being pressed together at the shores of Ross Island. Last year the sea ice broke out and therefore the ice is still relatively thin and many large bright blue meltwater ponds have formed.
Meltwater pond in the pressure ridges
Mt. Erebus is an active volcano that is ca. 3,700 metres high and is about 64 km away from Scott Base. Usually you can see little bit of smoke appearing from the top of the crater.
Pressure ridges and Mount Erebus
Every year a few Adelie and Emperor penguins can been seen near Scott Base. At the moment, there is a lone Emperor penguin wandering through the pressure ridges. The penguins come from parts of Ross Island where the sea ice breaks out every summer. The Emperor colonies on Ross Island are quite far away and nobody really knows if these individual penguins will be able to get back to the colonies. Let's hope for the best!
I'm Anne Jungblut from the Botany Department. Join me as I head to Antarctica to study cyanobacterial diversity in ice-covered lakes of the Dry Valleys and Ross Island where already scientists on Scott's and Shakleton's expeditions made many discoveries.