Structure of microbial communities in lake sediments of the High Arctic

Stuckberry Valley, located on the north shore of Ellesmere Island (Nunavut), approximately 800 km from the North Pole, was impacted by significant climatic variability during the Holocene and is an environment currently undergoing a rapid transition due to rising temperatures. The retreat of the valley’s main glacier resulted in the formation of four lakes, where the age of each lake is inversely related to the distance from the Arctic Ocean. Lacustrine sediments of these lakes represent a treasure-trove of information about past changes in the Stuckberry Valley watershed and provide a "long-term memory" of how the lakes’ responded to these changes. Microbes are the dominant form of life in this environment and thus understanding the diversity and distribution of microorganisms in the lakes’ sediments is essential to better understanding the effects of climate change on episodic and interannual changes in the biology of this valley. The specific objective of the study is to characterize changes over time in the structure of microbial communities by comparing microbial diversity in sediment cores from the four Stuckberry lakes, based on amplicon sequencing of viruses and bacteria. We hypothesize that microbial diversity will vary over time and that these dynamics will reflect past environmental changes in the catchment. We will also assess the differences in microbial diversity between the sediments of the four lakes and identify possible virus-host systems through network analysis. These data will provide new insight into microbial community succession in a region that is on the frontline of climate change.