Grand River Watershed Research Articles

Microbial communities change along the 300 km length of the Grand River for extreme high- and low-flow regimes.

The Grand River watershed is the largest catchment in southern Ontario. The river's northern and southern sections are influenced by agriculture, whereas central regions receive wastewater effluent and urban runoff. To characterize in-river microbial communities, as they relate to spatial and environmental factors, we conducted two same-day sampling events along the entire 300 km length of the river, representing contrasting flow seasons (high flow spring melt and low flow end of summer). Through high-throughput sequencing of 16S rRNA genes, we assessed the relationship between river microbiota and spatial and physicochemical variables. Flow season had a greater impact on communities than spatial or diel effects and profiles diverged with distance between sites under both flow conditions, but low-flow profiles exhibited higher beta diversity. High-flow profiles showed greater species richness and increased presence of soil and sediment taxa, which may relate to increased input from terrestrial sources. Total suspended solids, dissolved inorganic carbon, and distance from headwaters significantly explained microbial community variation during the low-flow event, whereas conductivity, sulfate, and nitrite were significant explanatory factors for spring melt. This study establishes a baseline for the Grand River's microbial community, serving as a foundation for modeling the microbiology of anthropogenically impacted freshwater systems affected by lotic processes.

Investigating wastewater treatment plant effluent and pharmaceutical exposure on innate cytokine expression of darters (Etheostoma spp.) in the Grand River watershed.

Fish live in continuous contact with various stressors and antigenic material present within their environments. The impact of stressors associated with wastewater-exposed environments on fish has become of particular interest in toxicology studies. The objectives of this study were to examine potential effects of wastewater treatment plant (WWTP) effluent-associated stressors on innate cytokine expression within the gills of darter species (Etheostoma spp.), using both field and laboratory approaches. Male and female darters (rainbow, greenside, fantail, and johnny darters) were collected upstream and downstream of the Waterloo WWTP in the Grand River, Ontario. Gill samples were collected from fish in the field and from a second subset of fish brought back to the laboratory. Laboratory fish were acutely exposed (96-h) to an environmentally relevant concentration of venlafaxine (1.0 μg/L), a commonly prescribed antidepressant. To assess the impacts of these stressors on the innate immunity of darters, the expression of key innate cytokines was examined. Minor significant effects on innate cytokine expression were observed between upstream and downstream fish. Moderate effects on cytokine expression were observed in venlafaxine-exposed fish compared to their control counterparts however, changes were not indicative of a biologically significant immune response occurring due to the exposure. Although the results of this study did not display extensive impacts of effluent and pharmaceutical exposure on innate cytokine expression within the gills, they provide a novel avenue of study, illustrating the importance of examining potential impacts that effluent-associated stressors can have on fundamental immune responses of native fish species.

Comparative Valuation of Three Ecosystem Services in a Canadian Watershed Using Global, Regional, and Local Unit Values

Economic valuations of ecosystem services often transfer previously estimated global unit values to the geographical setting of interest. While this approach produces quick results, its reliability depends on how representative the large-scale average unit values are for the given local context. Here, we estimate the values of three ecosystem services (ES)—water filtration, nutrient cycling, and carbon sequestration—in the Grand River watershed (GRW) of southern Ontario, Canada. The watershed covers nearly 7000 km2, has a humid continental climate and a population of close to one million people. Land cover is dominated by agriculture. We compare ES valuations using locally derived (i.e., GRW-specific) unit values to valuations based on unit values from a regional database and those compiled in the global Ecosystem Services Valuation Database (ESVD). The regional database includes mean unit values from three case studies within southern Ontario and one boreal watershed in British Columbia. As expected, the regional database yields average monetary values for the three ES that are close to those obtained using the local unit values but with larger associated uncertainties. Using the ESVD, however, results in significantly higher monetary values for the ES. For water filtration, the ESVD value is more than five times higher than the regional and local estimates. We further illustrate the effect of the extent of aggregation of forested and agricultural land categories on the ES values. For example, by subdividing the forest category into three subcategories (deciduous, coniferous, and mixed forest), the estimated value of the carbon sequestration service from forested areas within the GRW decreases by 7%. Overall, our results emphasize the importance of critically assessing the origin of unit values and the land cover resolution in ES valuation, especially when ES valuation is used as a policy-guiding tool.

Joint Flood Risks in the Grand River Watershed

According to the World Meteorological Organization, since 2000, there has been an increase in global flood-related disasters by 134 percent compared to the previous decades. Efficient flood risk management strategies necessitate a holistic approach to evaluating flood vulnerabilities and risks. Catastrophic losses can occur when the peak flow values in the rivers in a basin coincide. Therefore, estimating the joint flood risks in a region is vital, especially when frequent occurrences of extreme events are experienced. This study focuses on estimating the joint flood risks due to river flow extremes in the Grand River watershed in Canada. For this purpose, the study uses copula analysis to investigate the joint occurrence of extreme river flow events in the Speed and Grand Rivers in the Grand River Watershed in Ontario, Canada. By estimating the joint return period for extreme flows in both rivers, we demonstrate the interdependence of the two river flows and how this interdependence influences the behavior of river flow extreme patterns. Our findings suggest that the interdependence between the two river flows leads to changes in the river flow extreme pattern. Determining the interdependence of floods at multiple locations using state-of-the-art tools will benefit various stakeholders, such as the insurance industry, the disaster management sector, and most importantly, the public.

The Impact Of Urbanization on Water Quality and Riparian Land Cover Change in the Grand River Watershed

The research topic of my paper is the impact of urbanization on water quality and riparian land cover change in the Grand River watershed. Urban expansion could have unpredictable impacts on natural environment and resources. This watershed is comprised of lots of major rivers and tributaries in Canada which are significant hydrological resources to humans and nature, so it plays important roles in providing nearby residences water use and land irrigation. The watershed contains two First Nation territories and a total of 39 municipalities, including larger cities like Waterloo, Kitchener, Guelph, and Cambridge (GRCA 2008), so rapid urbanization could be one of the factors to degrade water quality and the underwater ecosystem. Moreover, due to the water quality change of the water, the riparian area land cover can correspondingly change over the years. Therefore, this study will mainly focus on studying water quality trends from 2000 to 2020, and data is collected from 12 water monitoring stations near the large cities in the watershed. The water quality will be defined by parameters like pH, temperature, conductivity, turbidity, and other chemical elements. The land cover layer of 2000 and 2020 will be used to compare the riparian land cover change, illustrating the spatial relationship of urban expansion and riparian area with significant land cover change. Furthermore, more discussions will focus on if the riparian land cover change is closely related to water quality degradation caused by urbanization. The final deliverable would be presented by ArcGIS pro layouts and statistic charts.

Future water security under climate change: a perspective of the Grand River Watershed

Abstract Climate change poses a threat to the water security of the Grand River Watershed (GRW) by altering the precipitation patterns and other weather variables, which affect streamflow and freshwater availability. Therefore, in this study, a Soil and Water Assessment Tool (SWAT) model for the GRW, Ontario, Canada, was used to assess the blue and green water scarcity for future periods for future sustainable management of freshwater resources in the region. The ensemble results predicted a warmer and wetter future for the GRW. The ensemble model result, when considering both emission scenarios and future periods, showed that blue water (BW) is projected to increase by 23–40% while green water storage (GWS) is projected to experience an overall decrease (2–8%). The results suggested that BW may become more scarce compared to green water in the future. The scarcity of BW is primarily due to the projected increase in population growth and water demand in the watershed. Green water scarcity in some regions indicated that changes in irrigation might be needed in the future in some parts of the watershed. The results indicate that the careful planning is essential for future water management in GRW.

Knowledge co-creation through Indigenous arts: Diversity in freshwater quality monitoring and management

In this paper, we recognize the need to diversify knowledge systems in freshwater quality monitoring. We acknowledge the importance of Canadian-Indigenous reconciliation and build on two recommendations from past work: (1) to recognize different forms of knowledge (including Indigenous and non-Indigenous community knowledge) and (2) to facilitate action by managers and decision-makers. Using a co-creative process, an artistic (i.e., art-based) research method was used to engage Indigenous youth in conversations about their relationships with the Grand River watershed (Ontario, Canada). We present six lessons learned from co-creating our process and six recommendations for those who hope to implement a similar approach. A list of 10 principles and values to guide water quality monitoring demonstrates how the collective perspectives of Indigenous youth and current water monitoring and management practitioners may be applied. Finally, we highlight three important factors for implementing such an approach as: relationship-building, capacity building, and reciprocation.

Collaborative watershed analysis: A ‘groupthink’ assessment of cumulative effects

In Canada, the assessment of cumulative effects, incremental and accumulating environmental changes in a region over time, emerged from environmental impact assessment, which was designed to serve the ethos of western, ‘settler’ governments despite being practiced in areas that usually overlap Indigenous territories. The limited (western) purview of cumulative effects assessment is reinforced by a lack of diversity in water monitoring and management practitioners. Our objective is to develop a new approach, collaborative watershed analysis, in which diverse ways of knowing are considered in the assessment of cumulative effects in water quality monitoring. An online workshop and 21 interviews informed how Canadian water managers, community members, and Haudenosaunee (Iroquois) peoples may collaborate to assess cumulative effects in the lower Grand River and the nearshore of Lake Erie (eastern basin in Ontario, Canada). Our results and discussion progress from western perspectives of ‘what is’ to a broader discussion of ‘what could be’, drawing on the perspectives of Haudenosaunee youth in the Grand River Watershed. We propose three recommendations for the creation of a cumulative effects monitoring framework: (1) co-create the intent and expectations of the monitoring program with all participants at the outset; (2) ensure diverse persons are invited to contribute; and (3) enable the sharing of knowledge in different formats. Strengths of collaborative watershed analysis include connecting biophysical aspects of the watershed with social, economic, and cultural aspects, as well as repositioning diverse ways of knowing as a foundation upon which cumulative impacts can be better understood and managed.

Impacts on antioxidative enzymes and transcripts in darter (Etheostoma spp.) brains in the Grand River exposed to wastewater effluent

The Grand River watershed is the largest in southern Ontario and assimilates thirty wastewater treatment plants (WWTP) with varied degrees of treatment. Many WWTPs are unable to effectively eliminate several contaminants of emerging concern (CECs) from final effluent, leading to measurable concentrations in surface waters. Exposures to CECs have reported impacts on oxidative stress measured through antioxidative enzymes (SOD, CAT, GPX). This study focuses on the effects of WWTP effluent on four Etheostoma (Darter) species endemic to the Grand River, by investigating if increased antioxidative response markers are present in darter brains downstream from the effluent outfall compared to an upstream reference site relative to the Waterloo, ON WWTP across two separate years (Oct 2020 and Oct 2021). This was assessed using transcriptional and enzyme analysis of antioxidant enzymes and an enzyme involved in serotonin synthesis, tryptophan hydroxylase (tph). In fall 2020, significant differences in transcript markers were found between sites and sexes in GSD with SOD and CAT showing increased expression downstream, in JD with both sexes showing increased SOD downstream, and an interactive effect for tph in RBD. Changes in transcripts aligned with enzyme activity where interactive effects with sex-related differences were observed in fish collected fall 2020. In contrast, transcripts measured in fall 2021 were increased upstream compared to downstream species in RBD and GSD. This study additionally displayed yearly, species and sex differences in antioxidant responses. Continued investigation on the impacts of CECs in effluent in non-target species is required to better understand WWTP effluent impacts.

Checkered landscapes: hydrologic and biogeochemical nitrogen legacies along the river continuum

Decades of agricultural intensification have led to elevated stream nitrogen (N) concentrations and eutrophication of inland and coastal waters. Despite widespread implementation of a range of strategies to reduce N export, expected improvements in water quality have not been observed. This lack of success has often been attributed to the existence of legacy N stores within the landscape. Here, we use the ELEMeNT-N model to quantify legacy accumulation and depletion dynamics over the last century (1930–2016) across 14 nested basins within the Grand River Watershed, a 6800 km2 agricultural watershed in the Lake Erie Basin. Model results reveal significant legacy N accumulation across the basin, ranging from 705 to 1071 kg ha−1, creating a checkered landscape of N legacies. The largest proportion (82%–96%) of this accumulated N is stored in soil organic N reservoirs, as biogeochemical legacy, and the remaining in groundwater, as hydrologic legacy. The fraction of N surplus accumulated in soil and groundwater is most strongly correlated with the calibrated watershed mean travel time µ, with the accumulation increasing with increases in µ. The mean travel time ranges from 5 to 34 years across the watersheds studied, and increases with increase in tile drainage, highlighting the strong control of anthropogenic management on legacy accumulation. Water quality improvement timescales were found to be heterogeneous across the watersheds, with greater legacies contributing to slower recovery.

Beyond the Mass Balance: Watershed Phosphorus Legacies and the Evolution of the Current Water Quality Policy Challenge

AbstractIncreased use of phosphorus (P) fertilizers and detergents and intensified livestock production have more than doubled P inputs to human‐impacted watersheds over pre‐industrial levels. While P fertilizer use and manure application help to maximize crop yields, excess P is lost to runoff, leading to eutrophication of downstream waters. Excess P also accumulates across the landscape, leading to legacies that serve as long‐term sources of P to surface waters, even after inputs to the watershed are reduced. Here, we have developed, for the first time, a process‐based model, Exploration of Long‐tErM Nutrient Trajectories‐Phosphorus, designed to capture legacy P accumulation and depletion trajectories along the land‐aquatic continuum. To drive the model, we have developed a more than 100‐year trajectory of watershed P inputs to the Grand River Watershed (GRW), Canada’s largest watershed draining directly to Lake Erie. Our results first show that net P inputs to the watershed approximately tripled between 1900 and the late‐1970s, when P surplus magnitudes peaked at approximately 15 kg ha−1 y−1. During this same period, stream P loads have increased more than fourfold, from 0.11 kg ha−1 y−1 in 1900 to 0.80 kg ha−1 y−1 in the 1970s. Since 1900, the GRW has served as a net P sink, with approximately 96% of net P inputs having been retained within the basin. Future simulations suggest that while 40% reductions in P loading in Lake Erie watersheds are possible under aggressive management scenarios, legacy P will continue to elevate P loads to Lake Erie for many decades to come.

Carbon stocks in riparian buffer systems at sites differing in soil texture, vegetation type and age compared to adjacent agricultural fields in southern Ontario, Canada

In any given watershed, riparian buffer systems (RBSs) can influence terrestrial carbon (C) sequestration and potentially enhance terrestrial C sinks. This study looked at the effects of soil texture, vegetation type and age on C stock sequestration in eight RBSs located within the Grand River Watershed (GRW), southern Ontario, Canada and compared the C stock with adjacent agricultural fields. Soil organic carbon (SOC) stocks on an equivalent mass basis were significantly higher (p<0.05) in mature buffers (192.7 Mg C ha-1) compared to adjacent agricultural fields (corn [Zea mays] –soybean [Glycine max] –wheat [Triticum aestivum] rotation), at 0-30 cm soil depth (88.2 Mg C ha-1), irrespective of soil texture and vegetation type of RBS. Sixty-year old deciduous tree buffers on clayey soils had the highest SOC concentration (5.94 %, p<0.05) at 0-30 cm soil depth while the young six-year old coniferous tree buffers on loamy soil had the lowest SOC concentration (2.87%). In mature deciduous [major species; sugar maple (Acer saccharum) and ash (Fraxinus excelsior)] buffers, biomass C stocks were 247 Mg C ha-1, which is up to two and half times greater than mature coniferous [major species; eastern white cedar (Thuja occidentalis) and white pine (Pinus strobus)] buffers (100 Mg C ha-1). Overall results support that increasing RBS within Ontario watershed areas can enhance C stocks and may contribute to Canada’s climate change mitigation efforts. In the context of riparian areas, deciduous species should be promoted over coniferous species to obtain higher terrestrial C sequestration within Ontario watersheds.

Investigation of Microplastics in Freshwater Mussels (Lasmigona costata) From the Grand River Watershed in Ontario, Canada

Microplastics have been identified as a widespread, persistent environmental pollutant. The investigation of microplastics in marine ecosystems has been prevalent in the literature; however, much less consideration has been given to this form of pollution in freshwater ecosystems. Relatively few studies have considered the uptake of microplastics in freshwater mussels. This study investigated the presence of microplastics in fluted-shell mussels (Lasmigona costata) collected from various sites in the Grand River watershed, Southern Ontario’s largest watershed and home to one million people. The soft tissue of adult mussels underwent enzyme digestion, followed by filtration to isolate undigested particles. Particles were removed and analyzed using Raman spectroscopy to determine their composition. Ten different polymers were identified in the sampled mussels, with polypropylene-co-polyethylene being the most prevalent. Microplastic particles were detected in 71% of mussels with the greatest number of particles observed in a single mussel being seven. No significant difference in microplastic particles per mussel was observed among the different sites sampled. A significant positive relationship between particles per mussel and size of upstream catchment was observed, but a relationship between particles per mussel and percentage of urban land use was not observed.

Antimicrobial resistance of Salmonella and generic Escherichia coli isolated from surface water samples used for recreation and a source of drinking water in southwestern Ontario, Canada.

Antimicrobial resistance (AMR) in the aquatic environment represents an important means of introduction and dissemination of resistance genes, and presence of resistant pathogens in surface waters may pose a public health concern to recreational and drinking water users. The purpose of this study was to explore antimicrobial resistance patterns in water samples collected from the Grand River watershed (southwestern Ontario, Canada) to describe the composition, trends and potential risks of AMR in the aquatic environment. As part of FoodNet Canada and the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS), stream water samples were collected bi-weekly from sampling sites within the Grand River watershed in the Waterloo, Ontario sentinel site and tested for the presence and antimicrobial susceptibility of Salmonella spp. (2005-2013) and generic Escherichia coli (2012-2013). Of all samples tested, 16% of Salmonella and 22% of E.coli isolates were resistant to at least one antimicrobial, including three Salmonella isolates and two E.coli isolates that were resistant to Category I antimicrobials, which are classified as very high importance for the treatment of serious bacterial infections in humans. The greatest proportion of resistant E.coli isolates were observed from the river site upstream of the drinking water intake, while the greatest proportion of resistant Salmonella isolates were from sites upstream in the watershed, and at one recreational water site. Salmonella resistance trends remained fairly stable between 2007 and 2013, with the exception of streptomycin and tetracycline which increased in 2010 and 2013. Continued surveillance of antimicrobial resistance patterns and exploration of risk factor data will allow for a better understanding of resistance transmission in the aquatic environment.

Water Security Assessment of the Grand River Watershed in Southwestern Ontario, Canada

Water security is the capability of a community to have adequate access to good quality and a sufficient quantity of water as well as safeguard resources for the future generations. Understanding the spatial and temporal variabilities of water security can play a pivotal role in sustainable management of fresh water resources. In this study, a long-term water security analysis of the Grand River watershed (GRW), Ontario, Canada, was carried out using the soil and water assessment tool (SWAT). Analyses on blue and green water availability and water security were carried out by dividing the GRW into eight drainage zones. As such, both anthropogenic as well as environmental demand were considered. In particular, while calculating blue water scarcity, three different methods were used in determining the environmental flow requirement, namely, the presumptive standards method, the modified low stream-flow method, and the variable monthly flow method. Model results showed that the SWAT model could simulate streamflow dynamics of the GRW with ‘good’ to ‘very good’ accuracy with an average Nash–Sutcliffe Efficiency of 0.75, R2 value of 0.78, and percentage of bias (PBIAS) of 8.23%. Sen’s slope calculated using data from over 60 years confirmed that the blue water flow, green water flow, and storage had increasing trends. The presumptive standards method and the modified low stream-flow method, respectively, were found to be the most and least restrictive method in calculating environmental flow requirements. While both green (0.4–1.1) and blue (0.25–2.0) water scarcity values showed marked temporal and spatial variabilities, blue water scarcity was found to be the highest in urban areas on account of higher water usage and less blue water availability. Similarly, green water scarcity was found to be highest in zones with higher temperatures and intensive agricultural practices. We believe that knowledge of the green and blue water security situation would be helpful in sustainable water resources management of the GRW and help to identify hotspots that need immediate attention.

Meeting updated phosphorus reduction goals by applying best management practices in the Grand River watershed, southern Ontario

Continued re-eutrophication of Lake Erie has led to the updated 2012 Great Lakes Water Quality Agreement (fully enacted in 2016) that established new binational phosphorus load reduction of 40% from 2008 baseline loading rates. Nonpoint source pollution is the leading cause of water impairment in agricultural watersheds; however, the water quality can be improved by implementing various BMPs for control of erosion and nutrient loss from watersheds. The Grand River watershed (GRW) occupies about 6800 km2 and is an important agricultural area in Southern Ontario. Changes in land use over the past century in the GRW have led to altered hydrology and greater export of sediment and nutrient loads into Lake Erie. The objective of this study was to investigate the impact of various BMPs in reducing sediment and phosphorus loading rates on various spatial and temporal scales in the watershed using SWAT for the years 2001–2010. The baseline sediment and P loading at Dunnville, prior to the Grand River’s discharge to Lake Erie, were predicted to be 2 × 105 tonnes y−1 and 2 × 105 kg y−1, respectively. Different source, transport and water body treatment BMPs were simulated. With respect to reducing sediment and P loading into Lake Erie, implementing wide buffer strips resulted in a decrease of 23% and 50%, respectively. Stabilizing channel banks resulted in reduced sediment and P loading of 38% and 36%, while grassed waterways resulted in reductions of 15% and 17%, respectively.

Modeling the Natural Drainage Network of the Grand River in Southern Ontario: Agriculture May Increase Total Channel Length of Low-Order Streams

The Grand River watershed is an important agricultural area in southern Ontario, with several large and growing municipalities. Based on digital elevation models (DEMs), the natural drainage network was modelled to predict flow paths. Channel lengths and locations of the predicted network were compared with a ground-truthed channel network to determine efficacy of the models. Approximately 5% of predicted channels lay &gt;40 m from actual channel locations. This amounted to 388 km of channel that had no corresponding channels in reality. The model was unable to predict, based on topography, 2535 km of actual channel present in the watershed. Channels not anticipated by topography were mostly first-order, with low sinuosity, were most common in areas with high agricultural land use, and are likely excavated extensions to headwater streams to facilitate drainage. In addition, this study showed that Soil and Water Assessment Tool (SWAT) models produced using different DEM resolutions did not predict significantly different stream flows, even when resolution was as low as 200 m. However, these low resolution DEMs did result in under-prediction of sediment export entering Lake Erie, most likely because the low resolution maps failed to account for small localized areas of high slope that would have relatively higher rates of erosion.

Statistical assessment of nonpoint source pollution in agricultural watersheds in the Lower Grand River watershed, MO, USA

The water quality in many Midwestern streams and lakes is negatively impacted by agricultural activities. Although the agricultural inputs that degrade water quality are well known, the impact of these inputs varies as a function of geologic and topographic parameters. To better understand how a range of land use, geologic, and topographic factors affect water quality in Midwestern watersheds, we sampled surface water quality parameters, including nitrate, phosphate, dissolved oxygen, turbidity, bacteria, pH, specific conductance, temperature, and biotic index (BI) in 35 independent sub-watersheds within the Lower Grand River Watershed in northern Missouri. For each sub-watershed, the land use/land cover, soil texture, depth to bedrock, depth to the water table, recent precipitation area, total stream length, watershed shape/relief ratio, topographic complexity, mean elevation, and slope were determined. Water quality sampling was conducted twice: in the spring and in the late summer/early fall. A pairwise comparison of water quality parameters acquired in the fall and spring showed that each of these factors varies considerably with season, suggesting that the timing is critical when comparing water quality indicators. Correlation analysis between water quality indicators and watershed characteristics revealed that both geologic and land use characteristics correlated significantly with water quality parameters. The water quality index had the highest correlation with the biotic index during the spring, implying that the lower water quality conditions observed in the spring might be more representative of the longer-term water quality conditions in these watersheds than the higher quality conditions observed in the fall. An assessment of macroinvertebrates indicated that the biotic index was primarily influenced by nutrient loading due to excessive amounts of phosphorus (P) and nitrogen (N) discharge from agricultural land uses. The PCA analysis found a correlation between turbidity, E. coli, and BI, suggesting that livestock grazing may adversely affect the water quality in this watershed. Moreover, this analysis found that N, P, and SC contribute greatly to the observed water quality variability. The results of this study can be used to improve decision-making strategies to improve water quality for the entire river basin.

Impacts of wastewater treatment plant effluent on energetics and stress response of rainbow darter (Etheostoma caeruleum) in the Grand River watershed.

The objective of this study was to assess the effects of municipal wastewater treatment plant effluent on the energetics and stress response of rainbow darter (Etheostoma caeruleum). Male and female rainbow darter were collected upstream and downstream of the Waterloo WWTP in the Grand River watershed, ON, Canada. To assess the effects of wastewater treatment plant effluent on whole-body and tissue specific metabolic capacity, closed-chamber respirometry and muscle-enzyme activity analyses were performed. Plasma cortisol was also collected from fish before and after an acute air-exposure stressor to evaluate the cortisol stress response in fish exposed to additional stressors. Male and female rainbow darter collected downstream of the effluent had higher oxygen consumption rates, while differences in enzyme activities were primarily associated with sex rather than collection site. No impairment in the cortisol stress response between downstream and upstream fish was observed, however baseline cortisol levels in female fish from the downstream site were significantly higher compared to other baseline groups. Stress-induced cortisol levels were also higher in female fish from both sites when compared to their male counterparts. Overall, this study demonstrates that chronic exposure to WWTP effluent impacts whole-body metabolic performance. This study was also able to demonstrate that sex-differences are a key determinant of various metabolic changes in response to physiological stress, thereby, providing a novel avenue to be considered and further explored.

Temporal trends in Giardia occurrence in the Grand River and surrounding tributaries, Waterloo, Ontario (2005-2013), a retrospective analysis of surveillance data.

Giardia contamination in the Grand River Watershed (south-western Ontario, Canada) was monitored from 2005 to 2013 as part of FoodNet Canada. Our study objectives were to describe the temporal pattern of Giardia occurrence and determine whether water quality parameters and bacterial indicators could act as effective markers for Giardia occurrence. Water samples were collected monthly from the Grand River near a drinking water intake point (2005-2013) and also collected intermittently from other areas in the watershed during the study period. Samples were tested for Giardia cysts using the US EPA method 1623. Samples were also tested for chemical and microbial water quality indicators. Univariable and multivariable linear regression models were built to examine whether temporal, water quality and bacterial indicators were associated with Giardia cyst concentration. Giardia cysts were identified in 89% of samples (n=228), with highest measured concentrations downstream of a waste water treatment plant outfall. Year and season were found to be predictors for Giardia occurrence. Concentrations were significantly higher in the winter and fall compared to the summer, and significantly higher in 2007 compared to other study years. After controlling for season, year and sampling location, dissolved oxygen was the only variable significantly associated with Giardia cyst concentration. Seasonal peaks in Giardia cyst concentrations in samples collected near the intake for the drinking water plant did not align with the seasonal peak in human Giardiasis cases in this region that are reported annually by public health authorities. This suggests that the risk of contracting Giardiasis from treated drinking water in this community is possibly low when the treatment plant is functioning adequately. Instead, waterborne exposure is likely the result of seasonal behaviours surrounding recreational water use. Therefore, the collective findings of our study are important to help inform future risk management studies and guide public health protection policies.