Abstract
During the attempt to directly access, measure and sample Subglacial Lake Ellsworth in 2012-2013, we conducted microbiological analyses of the drilling equipment, scientific instrumentation, field camp and natural surroundings. From these studies, a number of lessons can be learned about the cleanliness of deep Antarctic subglacial lake access leading to, in particular, knowledge of the limitations of some of the most basic relevant microbiological principles. Here, we focus on five of the core challenges faced and describe how cleanliness and sterilization were implemented in the field. In the light of our field experiences, we consider how effective these actions were, and what can be learnt for future subglacial exploration missions. The five areas covered are: (i) field camp environment and activities, (ii) the engineering processes surrounding the hot water drilling, (iii) sample handling, including recovery, stability and preservation, (iv) clean access methodologies and removal of sample material, and (v) the biodiversity and distribution of bacteria around the Antarctic. Comparisons are made between the microbiology of the Lake Ellsworth field site and other Antarctic systems, including the lakes on Signy Island, and on the Antarctic Peninsula at Lake Hodgson. Ongoing research to better define and characterize the behaviour of natural and introduced microbial populations in response to deep-ice drilling is also discussed. We recommend that future access programmes: (i) assess each specific local environment in enhanced detail due to the potential for local contamination, (ii) consider the sterility of the access in more detail, specifically focusing on single cell colonization and the introduction of new species through contamination of pre-existing microbial communities, (iii) consider experimental bias in methodological approaches, (iv) undertake in situ biodiversity detection to mitigate risk of non-sample return and post-sample contamination, and (v) address the critical question of how important these microbes are in the functioning of Antarctic ecosystems.
Highlights
Since the discovery of Antarctic subglacial aquatic ecosystems, there has been a rapid expansion in our understanding of these environments, their number [1], diversity [2] and interconnectivity [3]
To advance knowledge of subglacial lake microbiology, three ambitious projects aimed to access discrete subglacial aquatic systems and retrieve samples for analysis. These projects built on earlier observations of microbial activity made at the Kamb Ice Stream [9], Lake Vostok accretion ice [9,10], Blood Falls [11], Lake Vida [12] and Lake Hodgson [13]
We present the results of a combined laboratory and field study at the Lake Ellsworth drill site (Nov 2012–Jan 2013) to identify means to mitigate the effects of human impact in the lake through technology and logistics operations
Summary
Since the discovery of Antarctic subglacial aquatic ecosystems, there has been a rapid expansion in our understanding of these environments, their number [1], diversity [2] and interconnectivity [3]. To advance knowledge of subglacial lake microbiology, three ambitious projects aimed to access discrete subglacial aquatic systems and retrieve samples for analysis These projects built on earlier observations of microbial activity made at the Kamb Ice Stream [9], Lake Vostok accretion ice [9,10], Blood Falls [11], Lake Vida [12] and Lake Hodgson [13]. Lake Ellsworth, as all other Antarctic environments, is located in the most remote continent on the Earth, but has been physically separated from other continents since the detachment of Antarctica from the Gondwana supercontinent approximately 100 Ma ago This region is isolated from the rest of the world by the Southern Ocean, the Antarctic circumpolar current and the circumpolar vortex.
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