Unseen and Unknown: Microbial Community Diversity in a Rapidly Changing High Arctic Watershed on Northern Ellesmere Island, Canada

• Author / Creator

  Cavaco, Maria

• Arctic watersheds are currently undergoing great alterations due to human induced climate change. Current models predict increases in High Arctic temperatures and precipitation of up to 8.3°C and 40%, respectively, by 2100, which will have profound impacts on the arctic hydrological cycle, including enhanced glacial melt and permafrost thaw. However, it remains uncertain how this will impact the structure of downstream resident freshwater microbial communities and ensuing microbially driven freshwater ecosystem services. Using the Lake Hazen watershed (Nunavut, Canada, 81 N; 71 W) as a sentinel system for change, we characterized microbial community composition, using 16S rRNA gene sequencing, over a complete annual hydrological cycle, in relation to measured physicochemical parameters (e.g., temperature, dissolved oxygen, nutrients, major ions) in three freshwater compartments within the Lake Hazen watershed: i) glacial rivers; ii) permafrost thaw streams and the waterbodies they drain into, including small lakes and wetland areas, and; iii) Lake Hazen into which i) and ii) drain. Our findings show that microbial communities throughout these freshwater compartments are highly interconnected and are often shaped by the availability of melt-sourced chemicals (such as carbonates and sulfate) as the melt season progresses. Within Lake Hazen itself, microbial taxa were found to be generally stable over a spring and summer season, including members from phyla Chloroflexi and Elusimicrobia, indicating that microbial communities and the potential ecosystem services they provide therein may be somewhat resilient in the face of environmental change. Altogether, the work presented establishes a baseline understanding of how microbial communities and the ecosystem services they provide in Arctic watersheds might be reacting in response to climate change

• Subjects / Keywords

  • Arctic
  • freshwaters
  • watersheds
  • Lake Hazen
  • glacial rivers
  • permafrost thaw streams
  • biogeochemistry

• Graduation date

  Fall 2018

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3VX06K1H

• License

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