Concordia University

http://www.concordia.ca/content/concordia/en/artsci/biology/faculty.html

Faculty

David Walsh, PhD

Assistant Professor and Canada Research Chair in Microbial Ecology and Genomics, Biology

Office: L-GE 330-17 
Centre for Structural and Functional Genomics,
7141 Sherbrooke W.
Phone: (514) 848-2424 ext. 3477
Email: david.walsh@concordia.ca
Website(s): Visit our lab website

Education

PhD (Dalhousie)

Research interests

Microbial ecology and evolution, aquatic microbiology, symbiosis, genomics, metagenomics, marine hypoxia, carbon cycle, climate change.

Microbial Systems Ecology of the Coastal Ocean

In the Walsh lab, we are exploring the ecological and biogeochemical implications of marine microbial diversity using molecular and genomic approaches. Currently, we are focused on several interconnected research themes:



Monitoring, modeling and predicting microbial community dynamics. A general goal in microbial ecology is to predict the response of microbial systems to external disturbances, for example, a warming climate. Currently, predictions are hindered by an incomplete understanding of how environmental and biotic factors influence microbial community structure and function. In the Walsh lab, we are using the coastal ocean as a model ecosystem in which to advance microbial ecology towards a predictive science. We are monitoring the composition of microbial assemblages in relation to a long-term, high resolution oceanographic time-series of abiotic and biotic conditions at a temperate coastal ocean observatory. Through repeated observation over multiple years, we are identifying re-occurring patterns in microbial genetic and functional diversity that will inform the construction of ecological models of coastal microbial systems.



Reconciling diversity: organic matter and microbial communities. Oxygen deficiency (hypoxia) occurs in marine regions where high productivity fuels intense microbial respiration. Although a natural phenomenon, evidence points to human-driven expansion of hypoxia in both the coastal and open ocean. Oxygen depletion in the open ocean is intensifying, potentially driven by current climate trends. Similarly, excess nutrient input from industrial and agricultural activities are leading to an increase in the number of coastal hypoxic regions. We are investigating the causes and consequences of marine hypoxia from a microbial ecology perspective by studying microbial communities associated with hypoxic bottom waters of the Gulf of St. Lawrence and several coastal marine basins.

Causes and consequences of marine hypoxia.
Oxygen deficiency (hypoxia) occurs in marine regions where high productivity fuels intense microbial respiration. Although a natural phenomenon, evidence points to human-driven expansion of hypoxia in both the coastal and open ocean. Oxygen depletion in the open ocean is intensifying, potentially driven by current climate trends. Similarly, excess nutrient input from industrial and agricultural activities are leading to an increase in the number of coastal hypoxic regions. We are investigating the causes and consequences of marine hypoxia from a microbial ecology perspective by studying microbial communities associated with hypoxic bottom waters of the Gulf of St. Lawrence and several coastal marine basins.


Selected publications

Georges AA, El-Swais E, Craig SE, Li WK, Walsh DA. (2014) Metaproteomic analysis of a winter to spring succession in coastal Northwest Atlantic Ocean microbial plankton. ISME J. [Epub ahead of print]



Walsh DA, Lafontaine J, Grossart HP. (2013) On the eco-evolutionary relationships of fresh and saltwater bacteria and the role of lateral gene transfer in their evolution. In Lateral Gene Transfer in Evolution, U. Gophna (Ed). 55-77.



Walsh DA, Hallam SJ. (2011) Bacterial community structure and dynamics in a seasonally anoxic fjord: Saanich Inlet, British Columbia. In Handbook of Molecular Microbial Ecology II: Metagenomics in Different Habitats. FJ. de Bruijn (Ed).



Zaikova E, Walsh DA, Stilwell C, Mohn WW, Tortell PD, Hallam SJ. (2010) Microbial community dynamics in a seasonally anoxic fjord: Saanich Inlet, British Columbia. Environ Microbiol. 12: 172-191.



Walsh DA, Zaikova E, Howes CG, Song YC, Wright JJ, Tringe SG, Tortell PD, Hallam SJ. (2009) Metagenome of a versatile chemolithoautotroph from expanding oceanic dead zones. Science. 326: 578-82.

Walsh D.A. and Sharma A.K. (2009) Molecular phylogenetics: testing evolutionary hypotheses. Methods Mol Biol. 502: 131-68

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