Dr. David Walsh
Professor, Concordia University, Department of Biology
PI: Prof. Steven Short
March 14, 2025
12 to 1 PM
IB140 & Zoom
Title: Ecology and evolution of aquatic microbiomes: from inland lakes to the Arctic Ocean
Abstract: From inland waters to the open oceans, microorganisms comprise a diverse and essential component of Earth’s aquatic ecosystems. As the climate warms and human activities intensify, changes in the composition and activities of aquatic microbiomes are inevitable but difficult to predict. In this talk, I will present some of our recent work combining large-scale spatiotemporal surveys of aquatic ecosystems with meta-omics approaches to better understand the ecology and evolution of aquatic microorganisms in the context of a changing planet. Beginning with our research on freshwater systems, I’ll introduce a continental-scale study of lake microbiomes carried out in the context of the Canadian LakePulse Survey. Here we generated and analysed hundreds of lake metagenomes and used this resource to reveal terrestrial influences, including agriculture and urban development, on the structure and function of bacterial and micro-eukaryotic communities. Moving to our research in the ocean, I’ll introduce a multi-decadal time-series study of microbiomes from the rapidly changing Arctic Ocean. Here we have shown interannual changes in microbial diversity and community structure that may be related to ocean warming and Arctic sea ice loss. I’ll also present some interesting evolutionary adaptations we’ve discovered in Arctic Ocean microbiomes, including evidence for the unexpected role of terrestrial organic matter and volatile organic compounds in fueling microbial food webs. Overall, these studies are contributing to our fundamental understanding of microbial life, as well as insights into the trajectory of Earth’s aquatic ecosystems on a changing planet.
Background: Dr. Walsh holds a PhD from Dalhousie University and his current research focuses on aquatic microbial ecology and evolution, particularly studying microorganisms in aquatic ecosystems such as northern oceans, estuaries, and seasonally ice-covered lakes. His research investigates the biodiversity, metabolic versatility, and evolution of these microorganisms using genomics-based molecular approaches. These ecosystems are impacted by climate change and human activities. The goal is to understand how microbial distributions and activities are influenced by environmental pressures and, conversely, how these changes affect the broader aquatic ecosystem. Key areas include microbial ecology, evolution, aquatic microbiology, and metagenomics, with a focus on the Arctic Ocean.