Nowhere is climate change more dramatic than in the Arctic, where glacial melt and permafrost thaw greatly increase each year. Understanding the effect that such drastic changes present to microbial communities is vital as microorganisms often form an integral component of a freshwater’s metabolic and biogeochemical capacity. 

A new paper led by Maria Cavaco from the University of Alberta, Canada, and coauthored by Marek, just published in FEMS Microbiology Ecology, presents one of the first studies integrating microbial community interconnectivity and physicochemistry over an entire freshwater watershed system in the Canadian High Arctic. It determined that the microbial assemblages within a major lake receiving input from over 5 glacial systems forms a potentially stable community over time.

The field campaign used the unique Lake Hazen watershed, located on Northern Ellesmere Island, NU, Canada. This watershed represents an interconnected and diverse freshwater system composed of three basic compartments: glacially sourced rivers draining the northern Ellesmere Icefield, active layer thaw-fed sub-catchments, and Lake Hazen, the High Arctic’s largest lake by volume, which receives input from river and sub-catchment compartments at the heart of the watershed. The Lake Hazen watershed has experienced alterations due to climate change over recent decades, including soil warming and a 10-fold increase in glacial melt since 2007, with yet unknown consequences for the microbial ecology of downstream systems.

Using 16S rDNA amplicon sequencing, it was found that, over the course of a melt season, three distinct microbial communities characterized each of the three distinct freshwater compartments of the Lake Hazen watershed. Glacial river microorganisms were strongly impacted by the rate of sediment incorporation into glacial waters as they flowed downstream. In contrast, active layer thaw-fed communities were mostly influenced by evaporative processes characteristic of shallower bodies of water, delivering select communities to Lake Hazen.

Most of this study was written while Maria Cavaco was at Charles University, under a Michael Smith Foreign Study Scholarship (Natural Sciences and Engineering Research Council (NSERC), CGSM scholarship), with the CryoEco group.

Cavaco MA, St. Louis VL, Engel K, St. Pierre KA, Schiff SL, Stibal M, Neufeld JD (2019) Freshwater microbial community diversity in a rapidly changing High Arctic watershed. FEMS Microbiology Ecology 95:fiz161 doi: 10.1093/femsec/fiz161