From coast to coast: How cyanobacterial communities in the Atlantic and Pacific Maritime ecozones impact water quality and treatability

Tim Shardlow, recently graduated Master's student from the University of Waterloo, discussed his research at a webinar with the forWater Network.

Contact Elanor Waslander for access to the webinar recording.

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Webinar Overview: 
Healthy forested watersheds naturally provide high quality drinking water to communities. However, the integrity and quality of these water sources may be threatened by climate change-exacerbated disturbances which can lead to increased delivery of nutrients to receiving waters and increase in water temperatures. This can result in the proliferation of cyanobacteria that may threaten water quality through the production of toxins as well as taste and odour compounds. Hence, it is important to detect the presence of potentially harmful cyanobacteria prior to any associated water quality shifts. In this study, a synoptic field sampling campaign was conducted in summer and fall in 2019 and involved the collection of monthly water samples from the Pockwock Lake watershed (NS), the Comox Lake watershed (BC), and the Leech River and Sooke River watersheds (BC). To evaluate the composition and relative abundance of cyanobacteria, bacterial DNA was extracted from water samples for 16S rRNA gene sequencing and assigned taxonomy computationally in QIIME2 using a SILVA classifier and resulting cyanobacteria amplicon sequence variants (ASV) were analyzed using the R package mirlyn.

Lakes within the same watershed typically contained similar communities, though monthly variations in diversity were observed in some lakes. Most cyanobacteria ASVs were assigned to Cyanobium PCC-6307 and Rhabdogloea smithii SAG 47.91; across all samples, the relative abundance of reads from these genera was 51% and 42%, respectively. Other genera represented in the samples included cyanobacteria strains known to form blooms and produce geosmin, a terpene with an earthy odour, and microcystin, a hepatotoxin. Findings from this study provide insights into the presence of cyanobacteria in water resources relied upon as drinking water supplies and underscores some potential commonalities for their potential to deteriorate water quality and challenge drinking water treatability in diverse forested watersheds in Canada.

Pockwock Lake, a research site in this study.

Tim Shardlow's Biography
Tim is an environmental microbiologist specializing on the prevalence and distribution of cyanobacteria within water sources. While completing his BSc at the University of Waterloo, Tim conducted a senior honours thesis with Dr. Kirsten Müller which involved analyzing cyanobacterial communities in sediment from a drinking water reservoir. This inspired Tim to pursue being a water scientist as he continued working with Dr. Kirsten Müller as a graduate student. His Master’s research involved characterizing cyanobacterial communities from forested watersheds in the Atlantic and Pacific Maritime ecozones in Canada that are utilized as drinking water sources. 

Tim’s experience with studying cyanobacteria includes being in both the field and in the lab. As a BSc and MSc student, he assisted a PhD student from the Müller Lab with their field sampling efforts by collecting water samples from the Turkey Lakes Watershed. In the lab, he has performed numerous extractions of bacterial DNA from sediment and water filters as well as PCR amplification and gel electrophoresis to isolate and visualize the toxin marker gene for microcystin production. 

​As climate change is a major driver of cyanobacterial proliferation, Tim is particularly interested in monitoring shifts in cyanobacteria community composition and abundance due to changing environmental conditions and the impact these organisms have on water systems and water treatment plants through bloom formation, and the production of toxins as well as taste and odour compounds. By currently working as a lab technician for the Müller Lab and eventually continuing his research career, he looks forward to further developing skills and methods for the monitoring and detection of cyanobacteria and their associated toxins and taste/odour compounds.