Spatio-temporal connectivity of the aquatic microbiome associated with cyanobacterial blooms along a Great Lake riverine-lacustrine continuum

Abstract

Lake Erie is subject to recurring events of cyanobacterial harmful algal blooms (cHABs), but measures of nutrients and total phytoplankton biomass seem to be poor predictors of cHABs when taken individually. A more integrated approach at the watershed scale may improve our understanding of the conditions that lead to bloom formation, such as assessing the physico-chemical and biological factors that influence the lake microbial community, as well as identifying the linkages between Lake Erie and the surrounding watershed. Within the scope of the Government of Canada’s Genomics Research and Development Initiative (GRDI) Ecobiomics project, we used high-throughput sequencing of the 16S rRNA gene to characterize the spatio-temporal variability of the aquatic microbiome in the Thames River–Lake St. Clair-Detroit River–Lake Erie aquatic corridor. We found that the aquatic microbiome was structured along the flow path and influenced mainly by higher nutrient concentrations in the Thames River, and higher temperature and pH downstream in Lake St. Clair and Lake Erie. The same dominant bacterial phyla were detected along the water continuum, changing only in relative abundance. At finer taxonomical level, however, there was a clear shift in the cyanobacterial community, with Planktothrix dominating in the Thames River and Microcystis and Synechococcus in Lake St. Clair and Lake Erie. Mantel correlations highlighted the importance of geographic distance in shaping the microbial community structure. The fact that a high proportion of microbial sequences found in the Western Basin of Lake Erie were also identified in the Thames River, indicated a high degree of connectivity and dispersal within the system, where mass effect induced by passive transport play an important role in microbial community assembly. Nevertheless, some cyanobacterial amplicon sequence variants (ASVs) related to Microcystis, representing less than 0.1% of relative abundance in the upstream Thames River, became dominant in Lake St. Clair and Erie, suggesting selection of those ASVs based on the lake conditions. Their extremely low relative abundances in the Thames suggest additional sources are likely to contribute to the rapid development of summer and fall blooms in the Western Basin of Lake Erie. Collectively, these results, which can be applied to other watersheds, improve our understanding of the factors influencing aquatic microbial community assembly and provide new perspectives on how to better understand the occurrence of cHABs in Lake Erie and elsewhere.

Identification of potential microbial risk factors associated with fecal indicator exceedances at recreational beaches

“…At the phylum level, Proteobacteria, Bacteroidetes, Actinobacteria, Verrucomicrobia, and Firmicutes were abundant in all tested samples, consistent with other findings (surface water and sediment) for the Great Lakes region [ 24 , 52 , 53 ]. Interestingly, for Beach A, Cyanobacteria sequences were significantly more abundant in BAV non-exceedance samples than exceedance days or associated with the adjacent creek water source.…”

Algae in Recreational Waters: An Overview within a One Health Perspective

“…The protocols used led to an increase in the detection specificity [239][240][241]. HAB monitoring conducted in the Ohio inland lakes (Ohio, USA) between 2020 and 2022 demonstrated that qPCR and RT-qPCR can be considered extremely useful early warning tools to characterize cyanobacterial blooms and to identify cyanotoxin production [241][242][243]. Furthermore, compared with traditional microscopy and cell counting methods, qPCR is undoubtedly more rapid, providing results in 3 h [242].…”

“…HAB monitoring conducted in the Ohio inland lakes (Ohio, USA) between 2020 and 2022 demonstrated that qPCR and RT-qPCR can be considered extremely useful early warning tools to characterize cyanobacterial blooms and to identify cyanotoxin production [241][242][243]. Furthermore, compared with traditional microscopy and cell counting methods, qPCR is undoubtedly more rapid, providing results in 3 h [242]. Recent advances, associating PCR techniques with high-throughput sequencing of the 16s rRNA gene (e.g., Next-Generation Sequencing), are being employed as risk assessment ameliorating strategies [243].…”

Aquatic Bacterial Community Connectivity: The Effect of Hydrological Flow on Community Diversity and Composition

“…For example, high water velocity was reported to reduce microbial adhesion and the formation of biofilms relative to habitats with lower water velocities [22,24]. Microbial community connectivity fundamentally depends on the rate of microbial dispersal among patches within an environment [25,26]. Thus, high habitat connectivity (e.g., due to high water flow) is expected to result in reduced beta diversity across aquatic landscapes.…”