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Nitellopsis obtusa was first reported in North America in 1974. The overall ecological threat that N. obtusa poses towards freshwater ecosystems in its non‐native range is thought to be similar to other invasive macrophyte species. However, few studies have evaluated the impacts to aquatic communities upon successful establishment of this species in North America. Despite N. obtusa being a non‐native invasive species in North America, it is considered a beneficial macrophyte within its native range in EurasiaWe evaluated the impacts associated with the non‐native invasive charophyte N. obtusa on the lower aquatic food web (LAFW) communities (phytoplankton, macroinvertebrates, and macrophytes) in a large, shallow lake in Ontario, Canada. To tease apart abiotic and biotic factors that influence LAFW species assemblages, a generalised linear latent variable model (GLLVM) was used.Over the course of the 4‐year study period, N. obtusa abundance significantly increased throughout the lake (pairwise comparison, p < 0.001) and notable shifts in community composition occurred across years (PERMANOVA, p < 0.001), especially for the phytoplankton and macrophyte communities.Nitellopsis obtusa was also found to be associated with a decline in diversity, where Simpson's diversity indices across all LAFW communities decreased as a function of increasing N. obtusa biomass. The GLLVM analysis revealed significant negative associations between N. obtusa and the majority of LAFW taxa. Most notably, there was a significant (p < 0.001) negative relationship between Myriophyllum spicatum, a previously established non‐native invasive macrophyte, and N. obtusa. The GLLVM model also demonstrated that N. obtusa had positive co‐occurrence relationships with other members of the macrophyte community including Utricularia vulgaris, Najas flexilis, Potamogeton crispus, and Stuckenia pectinata.These results show for the first‐time significant impacts to the LAFW in an invaded ecosystem, which raises major concerns for fish communities that depend on the LAFW for food and habitat. Further studies are necessary to confirm the extent of these impacts in other invaded lakes. [ABSTRACT FROM AUTHOR]

This study was conducted in Lake Scugog, a large, shallow reservoir in Ontario, Canada. Historically, Lake Scugog has been a macrophyte-dominated ecosystem with a productive fishery. In recent years, periodic Microcystis blooms have erupted coinciding with the discovery of the non-native macroalga Nitellopsis obtusa in the lake. From 2016 to 2018, we conducted field surveys to assess the physical, chemical, and biological conditions across 12 sites spanning the lake. All study species (N. obtusa, Dreissena polymorpha, and Microcystis spp.) increased from 2016 to 2018. To determine potential biotic and abiotic drivers of Microcystis blooms, we used a structural equation modelling (SEM) approach. The SEM (r2 = 0.27, p < 0.05) revealed several positive (precipitation, chloride, depth, and N. obtusa) and negative (total nitrogen) explanatory variables for Microcystis biomass. The only statistically significant biotic driver was N. obtusa, which was a positive explanatory variable for both D. polymorpha and Microcystis. Future work will test the efficacy of the SEM model across Ontario lakes to confirm the facilitative role of N. obtusa on D. polymorpha and Microcystis populations. [ABSTRACT FROM AUTHOR]

• Nitellopsis obtusa was documented at 19 of the 60 lakes surveyed. • Shallow sites, that were closer to boat launches had higher densities of N. obtusa. • Cations other than calcium have a strong influence on N. obtusa distribution. Nitellopsis obtusa (also known as Starry Stonewort) is a Eurasian charophyte first introduced into the Laurentian Great Lakes in the 1970s. Over the last decade, there have been increasing reports of N. obtusa invasion of inland lakes in the Great Lakes basin. To improve our understanding of N. obtusa 's habitat preferences, we sampled 60 lakes across a geological transition zone in Ontario, Canada. Targeting this geological transition zone allowed us to study an array of lakes representing broad nutrient and water-hardness gradients within the same geographic and climatic region. Calcium is an important macronutrient for N. obtusa , thus it was anticipated that the presence of N. obtusa would respond strongly to calcium availability. Nitellopsis obtusa was documented at 37 sites in 19 of the 60 lakes surveyed. Lakes with N. obtusa had significantly higher cation (calcium, potassium, sodium, and magnesium) concentrations than lakes without N. obtusa (general linear mixed model with binomial error, p < 0.05). An ecological niche model based on a boosted regression tree (BRT) identified habitat features most associated with N. obtusa occurrence. Interestingly, the BRT model demonstrated that depth and the cations potassium, magnesium, and sodium were better predictors of N. obtusa presence than calcium. Although N. obtusa was found within a constrained range of calcium (15 – 57.9 mg L−1 Ca), it appears that other environmental parameters have a stronger influence on N. obtusa distribution in Ontario lakes. [ABSTRACT FROM AUTHOR]

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic presented the most challenging global crisis in recent times. A pandemic caused by a novel pathogen such as SARS-CoV-2 necessitated the development of innovative techniques for the monitoring and surveillance of COVID-19 infections within communities. Wastewater surveillance (WWS) is recognized as a non-invasive, cost-effective, and valuable epidemiological tool to monitor the prevalence of COVID-19 infections in communities. Seven municipal wastewater sampling sites representing distinct sewershed communities were selected for the surveillance of the SARS-CoV-2 virus in Durham Region, Ontario, Canada over 8 months from March 2021 to October 2021. Viral RNA fragments of SARS-CoV-2 and the normalization target pepper mild mottle virus (PMMoV) were concentrated from wastewater influent using the PEG/NaCl superspeed centrifugation method and quantified using RT-qPCR. Strong significant correlations (Spearman's r s  = 0.749 to 0.862, P < 0.001) were observed between SARS-CoV-2 gene copies/mL of wastewater and clinical cases reported in each delineated sewershed by onset date. Although raw wastewater offered higher correlation coefficients with clinical cases by onset date compared to PMMoV normalized data, only one site had a statistically significantly higher Spearman's correlation coefficient value for raw data than normalized data. Implementation of community stay-at-home orders and vaccinations over the course of the study period in 2021 were found to strongly correspond to decreasing SARS-CoV-2 wastewater trends in the wastewater treatment plants and upstream pumping stations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Water quality and phytoplankton community composition are important factors that can indicate freshwater ecosystem health. We combined water quality, phytoplankton community, and metabolomic data from algae and water sampled from two embayments in Lake Ontario, Hamilton Harbour and the Bay of Quinte, over ten weeks from August to October in the year 2020. Metabolomics was performed using liquid chromatography tandem mass spectroscopy (LC-MS/MS) to identify changes in intracellular metabolites within algae communities over time, and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was used to characterize putative isomers of extracellular metabolites at sub-ppb mass accuracy. Results from this study indicate that Hamilton Harbour and the Bay of Quinte are two very different ecosystems with respect to water quality, phytoplankton metabolites, and phytoplankton community composition. Community composition is strongly driven by conductivity and nitrates in Hamilton Harbour, while the opposite is true in the Bay of Quinte. Metabolites including α-aminobutyric acid and glycine were found in larger abundance within algal communities at both locations, while taurine was more predominant in algal communities from the Bay of Quinte. These metabolic profiles could reflect the different communities of phytoplankton, and be alternative indicators of algal bloom growth., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)