Supervised by:

Jérôme Comte (Regular Member (Co-researcher))

Research project description

Analyzing the impacts of dissolved organic matter with respect to lake core microbiome composition and functioning in the high Arctic

Introduction

My doctoral project is part of axis 2 of CEN, which aims to understand the responses of climate change in northern landscapes in the past, present, and future. Although it is understood that the effects of climate change are severely impacting Arctic environments, little is known about how these changes affect microbial taxonomic and functional diversity. With the accelerated loss of the cryosphere, the Arctic microbiome is losing its natural habitat and being exposed to higher levels of nutrient and carbon flow. Investigating the impact of these disturbances on microbial communities will make it possible to understand the present and future of how climate change is forcing microbial systems to adapt to new conditions in a warming world, as related to the second theme of axis 2 of CEN.

Objectives

There are three main objectives for this study: 1. Characterize the genomic properties of microbial communities among lakes differing in dissolved organic matter content, 2. Identify the core lake microbiome taxa and determine their emergent properties and important functionings , and 3. Assess the impact of dissolved organic matter enrichment on lake core microbiomes.

Study Sites

These objectives will be carried out using arctic lakes as the main sources of sampling content. Lakes will be located in and around Bylot Island (Nunavut). In addition, some temperate lakes, around Québec City, will also be investigated as it will allow for the comparison of lake core microbiomes along a latitudinal gradient.

Material and methods

Using community dissimilarity partitioning, I will estimate the relative contribution of the core microbiome, or the sum of microbial taxa consistently present in only the lake environment, to the overall gene pool for each lake in the study. I will then conduct a series of batch-culture experiments focusing on a high Arctic and a temperate lake to see if an increase in dissolved organic matter induces cascading changes from gene expression related to carbon metabolism to microbial processes at the ecosystem level. I will then investigate how taxa isolated from the core respond to dissolved organic matter fluctuations by conducting batch cultures on bacterial isolates. A unique combination of genomic, metabolic, and physiological data for northern aquatic ecosystems will be accumulated throughout the study.

Expected results

I expect to see notable differences in the microbial community composition between high arctic and temperate lake environments. As terrestrially derived dissolved organic matter features a high-diversity system with complex metabolic functions, it is expected that an increase in dissolved organic matter will shift the core microbiome to reflect that. Regarding bacterial isolates, it can be hypothesized that any metabolic or phenotypic changes that cells sourced from the different environments (either high arctic or temperate) will become apparent. By manipulating the amount and source of dissolved organic matter exposed to the isolates, the Arctic derived microorganisms will adapt features common to microorganisms from more temperate regions (which are exposed to higher levels of dissolved organic matter in a natural environment).

Research Site Coordinates