Thesis Defence: 16S rRNA-Based Profiling of Bacterial and Cyanobacterial Communities in Kelowna Stormwater Ponds

Anna Gyagbile Abbey, supervised by Dr. Sumi Siddiqua, will defend their thesis titled “16S rRNA-Based Profiling of Bacterial and Cyanobacterial Communities in Kelowna Stormwater Ponds: Influence of Environmental Factors on Bacterial Diversity and Cyanobacterial Community” in partial fulfillment of the requirements for the degree of Master of Applied Science in Civil Engineering.
An abstract for Anna Gyagbile Abbey’s thesis is included below.
Defences are open to all members of the campus community as well as the general public. Please email [email protected] to receive the Zoom link for this defence.
Abstract
Urban stormwater ponds are widely used as green infrastructure to reduce flooding and improve water quality; however, they often function as nutrient-enriched systems that support complex microbial communities. These conditions can promote cyanobacterial growth, including taxa associated with toxin production and taste-and-odour compounds, posing potential risks to downstream waters. In Kelowna, selected stormwater ponds drain into Brandt’s Creek and ultimately Okanagan Lake, the region’s primary drinking water source. Despite this connectivity, the spatiotemporal dynamics of bacterial and cyanobacterial communities and their environmental drivers remain poorly characterized.
A seasonal molecular survey of bacterial and cyanobacterial communities across five urban stormwater ponds was conducted from September 2024 to August 2025 using 16S rRNA gene amplicon sequencing integrated with physicochemical and climatic data. Bacterial communities were dominated by Pseudomonadota, Bacteroidota, and Actinomycetota, although relative abundances varied among ponds and seasons. Beta-diversity analyses indicated that pond identity explained more variation than season (ADONIS R² = 0.19–0.28, p ≤ 0.007), while seasonal effects were weaker but significant (R² = 0.10–0.14, p ≤ 0.041). Alpha diversity showed site-specific patterns, with higher richness and phylogenetic diversity in Redlich and Valleyview during summer.
Cyanobacteria comprised a minor but variable fraction of the assemblage. Cyanobium was the most prevalent genus across ponds and seasons and is a known producer of taste-and-odour compounds such as 2-methylisoborneol (2-MIB). Toxin-associated genera, including Microcystis, Pseudanabaena, Aphanizomenon, and Tychonema, occurred intermittently. Cyanobacterial abundance was positively correlated with water temperature, air temperature, dew point, solar radiation, and wind direction (Spearman correlation coefficient ρ,  0.491, 0.435, 0.495, 0.423,  and 0.358 – 0.466 respectively), and negatively correlated with oxidation–reduction potential (−0.503) and wind speed (-0.376).
Overall, these findings demonstrate that stormwater ponds support site-specific bacterial communities and that cyanobacterial dynamics are strongly influenced by temperature, redox conditions, and atmospheric factors. The presence of cyanobacterial taxa with known water-quality implications, even at low relative abundance, indicates that risks may occur outside visible bloom events. Integrating molecular (16S rRNA) monitoring with environmental data enables earlier detection of bloom-forming taxa and supports targeted management of stormwater ponds and protection of downstream drinking water sources such as Okanagan Lake.