Nitrogen (N) and phosphorus (P) concentrations in many northern prairie rivers have been increasing due to anthropogenic activities. While long-term trends in total N and P have been well documented, there remains limited knowledge regarding trends in dissolved fractions as well as the associated effects of shifting nutrient loadings on nutrient stoichiometry (i.e., N:P) of river water. We assessed long-term (25-year) trends in total and dissolved N and P concentrations and N:P at 11 monitoring stations situated on five rivers within the Red-Assiniboine River Basin in North America. We found that N and P concentrations and stoichiometry were changing through time at a majority of stations. Spatial patterns of trends were variable with no consistent directional changes in either nutrient concentrations or stoichiometry among stations, suggesting the importance of localized nutrient sources, such as wastewater treatment plants. Changes associated with catchment characteristics were the primary contributors to observed trends in nutrient concentrations and stoichiometry, whereas alterations in the streamflow regime played a comparatively minor role. Variations in the relative quantities of nutrients in the basin’s rivers may be influencing the potential for nutrient depletion, with some rivers undergoing stoichiometric shifts in the depleted nutrient. Consequently, nutrient management may need to occur at the sub-basin scale to mitigate point source nutrient pollution and protect riverine water quality throughout the basin.

Lake Winnipeg, Canada, has been experiencing extensive nuisance and toxic algal blooms for over two decades. Blooms are linked to increased phosphorus (P) loadings from tributaries, including the Red River, which contributes 70% of inflowing P. Red River P loads were identified to be increasing nearly 20 years ago; however, studies have not assessed trends in the major P fractions (i.e., particulate and dissolved phosphorus) or in individual seasons. Drivers of trends have also not been identified. Our study assessed annual and seasonal trends in concentrations and loads of total phosphorus (TP), particulate phosphorus (PP), and total dissolved phosphorus (TDP) and determined if trends were associated with changes in hydrologic, climatic, and/or anthropogenic conditions. TP loads have more than tripled since 1960, primarily due to increases in TDP during the snowmelt and summer seasons. As a result, the dominant fraction of P in the Red River has shifted from PP to TDP. Trends in P are positively associated with increasing discharge and precipitation. Trends also correspond to increased release of treated municipal wastewater and greater P fertilizer application in the basin. In addition, results indicated that management actions to reduce PP losses from agricultural lands have been effective, but new management actions targeting TDP losses are needed, especially for the summer season. Development of strategies to address these emerging needs would benefit from assessments of sources associated with increasing P loadings as well as hotspot analyses to target locations where management can efficiently prevent P losses to the Red River.

Nuclear magnetic resonance (NMR) spectroscopy is a fundamental tool of metabolomics, valued for its reproducibility, quantitative accuracy and broad applicability across biological, chemical and clinical sciences. However, methodological inconsistencies, insufficient protocol reporting and limited infrastructure continue to hinder reproducibility and data sharing. To assess the current state of NMR metabolomics practice, we developed a comprehensive questionnaire and distributed it worldwide to researchers engaged in NMR-based metabolomics. We received 75 responses from a diverse cohort of investigators from academia, clinics and core facilities. The survey focused on Quality Assurance (QA) and Quality Control (QC) practices and provides an overview of the current status of NMR metabolomics and its implementation. Results reveal that while 86% of laboratories have Standard Operating Procedures (SOPs), deviations from these protocols are common and often undocumented, undermining reproducibility. QC practices, including pooled samples and system suitability checks, are widely recognized, but their implementation is inconsistent. Data accessibility remains limited, with fewer than 10% of respondents routinely depositing raw or processed spectral data in public repositories. Formal regulatory oversight and dedicated QA personnel are uncommon. Training is largely informal, with substantial gaps in areas such as data analysis and statistics, raising concerns about knowledge transfer and methodological consistency. Our findings describe a technically skilled community that is constrained by variations in NMR infrastructure and inconsistent implementation of best practices. Addressing these issues through adaptive standardization, structured training programs, and stronger institutional support is critical for advancing transparency, reproducibility and impact of NMR in metabolomics.

Stream water nutrient ratios are often influenced by flow variation and landscape characteristics. However, the influence of these drivers on total and dissolved nutrient ratios remains understudied, especially in prairie ecosystems where hydrologic connectivity between soils and streams exhibits substantial spatial and seasonal variability. Here, we ask how hydrology and land cover drive patterns of nitrogen (N), phosphorus (P), and N : P ratios across streams and rivers draining northern prairie ecosystems. To answer this, we compiled nutrient concentration data for tributaries of the Red River, Manitoba, Canada, to assess seasonal and annual variation in nutrient ratios, as well as the relationship between crop cover, discharge, and ratios, over 1-yr, 10-yr, and 30-yr time spans. Total nitrogen : total phosphorus ratios were near the Redfield mass ratio (N/P = 7.23) across 24 streams in the Red River Valley. By comparison, dissolved inorganic nitrogen : total dissolved phosphorus ratios in these streams were N depleted and generally declined from spring through to autumn. The types of crops grown did not appear to be a consistent influence on nutrient ratios in streams throughout the region. In contrast, stream flows strongly influenced spring and summer nutrient ratios in four tributaries over a 30-yr period. Specifically, increasing stream flow tended to decrease TN : TP and DIN : TDP in the two eastern tributaries but increase DIN : TDP in the western tributaries. Our findings that nutrient ratios in prairie streams are impacted by seasonality and fluctuating hydrologic conditions suggest that nutrient ratios in Red River tributaries may be impacted by future climate change.

The past 50 years have seen biomonitoring emerge as an essential means of generating the knowledge needed to inform protection and restoration of freshwater ecosystems. Despite the successes of biomonitoring, most freshwater ecosystems remain unmonitored. Moreover, degradation of freshwaters continues at a rapid rate with new threats and novel stressors emerging that are difficult to assess using existing techniques. New technologies and techniques have been developed to improve biomonitoring, but application has been slow and integration with existing approaches is often problematic. Clearly, freshwater biomonitoring faces many important challenges that must be addressed to meet management needs of the coming decades. We identify Grand Challenges facing freshwater biomonitoring with the aim of encouraging research and practice to address these challenges. We asked 256 biomonitoring scientists from around the globe to identify what they considered the most important challenges. From their submissions we established five Grand Challenges and 18 associated subchallenges. For each Grand Challenge, we outline the current state of biomonitoring practice and suggest promising pathways and approaches to address them. By identifying and describing these challenges, we strive to position freshwater biomonitoring to take advantage of emerging opportunities and enhance its capacity to meet current and future management needs.

Metabolomics is a rapidly growing multidisciplinary field with ever increasing demand and usability, which is attracting a surge of new researchers. While their varied skill sets, scientific questions, and approaches enrich the field with fresh perspectives and innovation, individual investigators also bring wide-ranging levels of metabolomics-specific experience and diverse areas of interest. These factors introduce considerable variability and inconsistency in both the methodology and reporting. A recent comparative literature review of nuclear magnetic resonance (NMR) metabolomics from studies published in 2010 and 2020 revealed significant shortcomings in the reporting of experimental details necessary for evaluating both the scientific rigor and the reproducibility of NMR-based metabolomics experiments. Each stage of metabolomics research contains multiple methodological choices and various optimization parameters, all of which can introduce experimental bias and alter the study results. This emphasizes the need for proper reporting to enhance reproducibility, data reusability, and study comparability. To address these concerns, the NMR Special Interest Group within the Metabolomics Association of North America presents reporting recommendations focused on fundamental aspects of NMR metabolomics research identified from the detailed literature review report. These include specifics with respect to study design, sample preparation, data acquisition, data processing and analysis, data accessibility, and comparability to previous studies. Also presented is a complementary list of seminal papers in the field to guide the study design and implementation of NMR metabolomics experiments. This initiative seeks to enhance the long-term impact of NMR metabolomics by supporting high-quality, reproducible, and impactful data collected from well-executed and thoroughly reported studies.

A literature survey was conducted to identify current practices used by NMR metabolomics investigators when conducting and reporting their metabolomics studies. A total of 463 papers from 2020 to 80 papers from 2010 were selected from PubMed and were manually analyzed by a team of investigators to assess the extent and completeness of the experimental procedures and protocols reported. A significant number of the papers did not report on essential experimental details, incompletely stated which statistical methods were used, improperly applied supervised multivariate statistical analyses, or lacked validation of statistical models. A large diversity of protocols and software were identified, which suggests a lack of consensus and a relatively limited use of commonly agreed upon standards for conducting and reporting NMR metabolomics studies. The overall intent of the survey is to inform and encourage the NMR metabolomics community to develop and adopt best practices for the field.

It has been proposed that biomonitoring may benefit from the use of metabolomics (the study of all small molecules in an organism) to detect sub-lethal organism stress through changes in the metabolite profile (i.e., the metabolome). However, to integrate the metabolome into biomonitoring programs the amount of natural variability among and within populations of indicator taxa must be established prior to generating a reference condition. This study determined variation in the metabolome among ecoregion and stream of origin in the northern crayfish (Faxonius virilis) and if that variation inhibited detection of stressor effects at sites exposed to human activities. We collected crayfish from seven minimally disturbed streams (i.e., reference streams), distributed across three level II ecoregions in central Canada and compared their metabolomes. We found ecoregion and stream origin were poor predictors of crayfish metabolomes. This result suggests crayfish metabolomes were similar, despite differing environmental conditions. Metabolomes of crayfish collected from three stream sites exposed to agricultural activity and municipal wastewater (i.e., test sites) were then compared to the crayfish metabolomes from the seven reference streams. Findings showed that crayfish metabolomes from test sites were strongly differentiated from those at all reference sites. The consistency in the northern crayfish metabolome at the studied reference streams indicates that a single reference condition may effectively detect impacts of human activities across the sampled ecoregions.

Rivers are often exposed to multiple stressors, such as nutrients and contaminants, whose impacts on the river food webs may not be distinguished by sole assessment of biological community structures. We examined the benthic algal assemblages and the fatty acids (FA) of benthic macroinvertebrates in the lower Athabasca River in Canada, aiming to assess the changes in algal support and nutritional quality of the benthic food web in response to cumulative exposure to natural bitumen, municipal sewage discharge (hereafter, "sewage"), and oil sands mining ("mining"). Data show that the decline in water quality (increases in nutrient concentrations and total suspended solids) was associated with decreases in benthic diatom abundance, and was driven mainly by sewage-induced nutrient enrichment. Responses in nutritional quality of benthic macroinvertebrates, indicated by their polyunsaturated FA (PUFA) concentrations, were taxon- and stressor-specific. Nutritional quality of the larval dragonfly predator, Ophiogomphus, decreased nonlinearly with decreasing benthic diatom abundance and was lowest at the sewage-affected sites, although exposure to natural bitumen also resulted in reduced Ophiogomphus PUFA concentrations. In contrast, the PUFA concentrations of mayfly grazers/collector-gatherers were not affected by natural bitumen exposure, and were higher at the sewage and sewage+mining sites. The PUFA concentrations of the shredder Pteronarcys larvae did not change with cumulative exposure to the stressors. Sediment metal and polycyclic aromatic compound concentrations were not associated with the macroinvertebrate FA changes. Overall, we provide evidence that sewage induced reduction in trophic support by PUFA-rich diatoms, and was the predominant driver of the observed changes in FA composition and nutritional quality of the benthic macroinvertebrates. Fatty-acid metrics are useful to untangle effects of concurrent stressors, but the assessment outcomes depend on the functional feeding guilds used. A food-web perspective using multiple trophic levels and feeding guilds supports a more holistic assessment of the stressor impacts.

This chapter discusses the five major rivers of the Mackenzie River system demonstrating the large range of natural diversity and human impacts evident within the basin. These rivers include the Athabasca, Peace, and Slave, which drain the most southern reaches of the watershed, and the Liard River and the main stem of the Mackenzie River, both of which are located north of Great Slave Lake. The chapter also provides a brief overview of physical, chemical, and biological characteristics and human uses of these rivers, and five other rivers of the Mackenzie River basin (Smoky River, Hay River, Yellowknife River, South Nahanni River, and Peel River). Major threats to the rivers are land-use changes, including agriculture, forestry, and mining, hydrologic fragmentation through the creation of reservoirs, and point-source inputs from industry and municipalities. Damming of the Peace River has caused impacts on the Peace–Athabasca Delta approximately 1200km downstream of Williston Reservoir. Commercial fishing is important on basin lakes such as Great Slave Lake and Lake Athabasca, and aboriginal peoples of the basin continue to use wildlife resources for food and furs.

Study region: The Lake Winnipeg Basin in the northern Great Plains of North AmericaStudy focus: Assessment of trends in total nitrogen (TN), total phosphorus (TP) and total sus-pended solids (TSS) for 18 river stations in the Lake Winnipeg Basin for the period of 1996-2016 using a Weighted Regressions on Time, Discharge and Season (WRTDS) modeling approach.New hydrological insights for the region: We observed rapidly increasing concentrations, loads, and yields of TN, TP and TSS at most of the evaluated river monitoring stations in the eastern half of the basin. In contrast, nutrient and suspended solid loads tended to exhibit decreasing or sta-tionary trends at most of the more western stations. Trends in nutrients and suspended solids typically corresponded to discharge, particularly in the Red-Assiniboine subdrainage where rapidly increasing nutrient loads were almost exclusively associated with runoff patterns. Our findings will serve as a baseline against which future trend assessments can be compared. Moreover, our findings suggest that land management practices aimed at reducing nutrient loads to Lake Winnipeg should be prioritized towards the rivers of the eastern subdrainages of the Lake Winnipeg basin.

Since 1997, sediment metal concentrations have been monitored in the Alberta Oil Sands Region (AOSR) of the Lower Athabasca River by the Regional Aquatics Monitoring Program (RAMP; 1997-2002), the Joint Oil Sands Monitoring Program (JOSM; 2012-2014), and the Oil Sands Monitoring Program (OSM; 2015-present). However, it has remained difficult to differentiate industrial sources from natural sources and quantify the extent of pollution due to inadequate knowledge of predevelopment reference conditions. Here, baselines were constructed using predevelopment (i.e., pre-1967) sediment concentrations of US EPA priority pollutants (Be, Cr, Cu, Ni, Pb) and V, an element elevated in bitumen and associated waste materials, normalized to Al concentration in cores from floodplain and upland lakes within the AOSR to characterize the natural range of variability. The Lower Athabasca River sediment metal monitoring data were examined in the context of the predevelopment baselines. Most metals are below the threshold for minimal enrichment (<1.5x baseline) except for chromium (up to 4.8x) in some RAMP samples. The predevelopment baselines for sediment metal concentrations will be of particular importance as the oil sands industry potentially shifts from a no-release policy to the treatment and release of oil sands process waters directly to the Lower Athabasca River.

The oil sands region in northeastern Alberta, Canada contain approximately 165 billion barrels of oil making it the third largest oil reserves in the world. However, processing of extracted bitumen generates vast amounts of toxic byproduct known as oil sands process waters. Naphthenic acids and associated sodium naphthenate salts are considered the primary toxic component of oil sands process waters. Although a significant body of work has been conducted on naphthenic acid toxicity at levels comparable to what is observed in current oil sands process waters, it is also important to understand any impacts of exposure to sublethal concentrations. We conducted a microcosm study using the mayfly Hexagenia spp. to identify sublethal impacts of naphthenic acid exposure on the survival, growth, and metabolome across a concentration gradient (0–100 μg L−1) of sodium naphthenate. Nuclear magnetic resonance-based metabolomic analyses were completed on both the polar and lipophilic extracted fractions of whole organism tissue. We observed a positive relationship between sodium naphthenate concentration and mean principal component score of the first axis of the polar metabolome indicating a shift in the metabolome with increasing naphthenic acid exposure. Eleven metabolites correlated with increased naphthenic acid concentration and included those involved in energy metabolism and apoptosis regulation. Survival and growth were both high and did not differ among concentrations, with the exception of a slight increase in mortality observed at the highest concentration. Although lethal concentrations of naphthenic acids in other studies are higher (150–56,200 μg L−1), our findings suggest that physiological changes in aquatic invertebrates may begin at substantially lower concentrations. These results have important implications for the release of naphthenic acids into surface waters in the Alberta oil sands region as an addition of even small volumes of oil sands process waters could initiate chronic effects in aquatic organisms. Results of this research will assist in the determination of appropriate discharge thresholds should oil sands process waters be considered for environmental release.

Municipal wastewater treatment plant (WWTP) effluents are significant sources of organic and inorganic pollutants to aquatic ecosystems. Several studies have shown that the health of aquatic organisms can be adversely impacted following exposure to these complex chemical mixtures. The objective of this study was to examine the effects of in situ exposure in the St. Lawrence River (QC, Canada) of juvenile yellow perch (Perca flavescens) to a major WWTP effluent. Perch were caged at a reference site in the St. Lawrence River and downstream of a WWTP effluent-influenced site for one, three, and six weeks. Fish kept in controlled laboratory setting were also examined at the beginning of the experiment to evaluate the potential effect of caging on fish. Liver metabolites and gill oxidative stress biomarkers as well as body condition of perch were investigated at four time points (zero, one, three, and six weeks). Nitrogen (δ15N) and carbon (δ13C) stable isotopes as well as tissue concentrations of halogenated flame retardants and trace metals were also analyzed. Results indicated that body condition of perch caged in the effluent increased after three and six weeks of exposure compared to that of reference fish. Perch caged at the WWTP effluent-influenced site also had higher muscle δ13C and slightly depleted muscle δ15N after three and six weeks of exposure, suggesting differences in sewage-derived nutrient assimilation between sites. Concentrations of Σ34 polybrominated diphenyl ether (PBDE) were 2-fold greater in perch exposed downstream of the WWTP compared to those caged at the reference site. Metal concentrations in kidney of perch after three weeks of exposure were significantly lower at the effluent-influenced site. Kidney concentrations of Cd, Cu, Se, As, Zn and Fe were, however, higher after six weeks of exposure, supporting that metal accumulation is time- and element-specific. The metabolomes of perch from the effluent-influenced and reference sites were similar, but were distinct from the laboratory control fish, suggesting a caging effect on fish. Seven liver metabolites (glucose, malate, fumarate, glutamate, creatinine, histamine, and oxypurinol) were significantly more abundant in perch from cages than in the laboratory control perch. The combination of metabolomics and physiological variables provides a powerful tool to improve our understanding of the mechanisms of action of complex environmental pollutant mixtures in wild fish.

Lake Winnipeg is the 10th largest freshwater lake in the world and, like many of the world’s great lakes, it is increasingly being affected by anthropogenic pressures, such as high nutrient loads and invasive species. The consequences of these on the hydrology and ecology of the lake are the focus of continuing research, funded by the renewed investment of Federal and Provincial agencies. Complicating this, Lake Winnipeg is still very much a wilderness lake and despite two decades of research there is much we don’t know. This second special issue on Lake Winnipeg is a collection of 21 research articles that describe some of the most recent and emerging research on the lake.

Oil sands development in the lower Athabasca River watershed has raised considerable public and scientific concerns regarding perceived effects on environmental health. To address this issue for tributaries and the mainstem of the Athabasca River in the Athabasca Oil Sands Region, the Water Component of the Joint Oil Sands Monitoring (JOSM) plan produced monitoring assessments for seven integrated themes: atmospheric deposition, tributary water quality, river mainstem water quality, groundwater quality and quantity, water quality and quantity modelling, benthic invertebrate condition, and fish health. Our review integrates and synthesizes the large and diverse datasets assembled in the seven JOSM theme assessments to (i) evaluate possible environmental effects based on known sources and candidate proximal causes and (ii) determine the importance of cause-and-effect pathways related to contaminant, sediment, and nutrient inputs. Although JOSM research identified ecological effects that appear to be associated with contaminant exposure, the source of this exposure is confounded by co-location of, and inability to differentiate between, oil sands operations (principally released by atmospheric emission) and inputs from the natural bitumen outcrops (e.g., erosional material transported by surface and groundwater flows). Nutrient enrichment from treated municipal sewage effluent was the dominant ecological effect observed for the mainstem Athabasca River, associated with increased fish size and changes in invertebrate assemblages, likely because this pollution source is discharged directly into the river. If the direct release of treated oil sands process water occurs in the future, then the potential ecological impact of these direct industry releases will need to be evaluated carefully. The ecological causal assessment method proved to be a useful tool for better understanding how stressor sources relate to ecological effects through candidate proximate causes. Factors that confound our ability to assess the ecological effects of oil sands development focus on our inability to adequately differentiate between contaminants supplied from natural and anthropogenic contaminant sources. Our causal synthesis identifies options for changes in future monitoring to better anticipate and detect degradation in the ecosystem health of the lower Athabasca River and its tributaries.

Antimicrobials used in livestock production can be present in manure via excretion in the feces and/or urine. Application of raw or processed (composted or stockpiled) manure to crop and pasture land as a plant nutrient source can result in antimicrobial transport to surface waters via rainfall or snowmelt runoff. Little is known regarding antimicrobial persistence in aquatic ecosystems. Consequently, dissipation of environmentally relevant concentrations of three veterinary antimicrobials (lincomycin, chlortetracycline, and sulfamethazine) was studied in three wetlands on the Canadian Prairies. Study wetlands were fortified in the fall to simulate antimicrobial transport via rainfall runoff from fall manure applications to the wetland catchments. After fortification, water column concentrations of all three antimicrobials decreased through September and October. Plotting natural logarithm values of antimicrobial concentration against time resulted in linear relationships for all three antimicrobials, indicating that the summation of all dissipation processes for each antimicrobial could be described by first-order kinetics. The slopes of the three plots were significantly different, indicating that the order of dissipation was lincomycin < sulfamethazine < chlortetracycline. Consequently, the dissipation DT50 (time required for 50% antimicrobial dissipation) values for lincomycin (14.0 d), sulfamethazine (7.0 d), and chlortetracycline (3.3 d) were significantly different. The longer DT50 values of lincomycin and sulfamethazine suggest that environmentally relevant concentrations of these antimicrobials may affect bacterial production in prairie wetlands.

Intensive agriculture and growing human populations are important nitrogen (N) sources thought to be associated with eutrophication. However, the contribution and seasonality of N delivery to streams from human activities is poorly understood and knowledge of the role of stream communities in the assimilation of N from human activities is limited. We used N and oxygen stable isotope ratios of dissolved inorganic N (DIN) and concentrations of artificial sweeteners to identify the relative contribution of key sources of anthropogenic N (i.e., fertilizers, human, and livestock waste) to tributaries of the Red River Valley (RRV), Manitoba, Canada. Water and algae were sampled in 14 RRV tributaries during snowmelt, spring, summer, and autumn; and water was sampled at three locations in the Red River in spring, summer, and autumn. δ15N values of DIN in tributary water differed seasonally and were greatest during snowmelt. Incorporation of ammonium δ15N provided evidence for the importance of manure N to tributaries during snowmelt. Fertilizer and municipal lagoons served as principal sources of N to streams in spring and summer. Human and livestock waste sources of N were the dominant contributor to algae at greater than 90% of sites and algae δ15N was greatest at sites downstream of municipal lagoons. We also showed that the tributaries contribute human and livestock waste N to the Red River, though much of the nitrate in the river originates outside of Manitoba. Overall, our study determined that the anthropogenic sources of N to RRV streams vary seasonally, likely due to regional hydrologic conditions. Our study also showed the potential of artificial sweeteners and ammonium δ15N as tools for identifying N sources to rivers. Moreover, we demonstrate the need for the management of N sources and the protection of stream function to control downstream transfer of N from landscapes to waterbodies.

Water resources on the Canadian Prairies are at risk due to human settlement, agricultural intensification, and climatic change. The Red River Valley (RRV), Manitoba, Canada, represents a nexus of these cumulative stressors. Here land use change, combined with a recent increase in precipitation and runoff, imperils the protective function of tributaries draining to Lake Winnipeg. A concerted research effort over the past decade has greatly improved availability of data and knowledge about the RRV. However, a full synthesis of these data and information remain lacking. We undertook a review to identify and compare contemporary and historical land use, climatic, hydrologic, and water quality condition within the RRV. Then, using current knowledge of the ecological condition of streams in the RRV and elsewhere, we completed an ecological causal assessment of RRV tributaries to identify linkages and knowledge gaps between anthropogenic drivers and ecological endpoints. We found wastewater to be the candidate cause of ecological effects in RRV streams best supported by empirical evidence. A lack of complete lines of evidence linking agriculture, the greatest diffuse source of nutrient inputs, and ecological effects in RRV tributaries underscored a need for stressor-specific indicators and improved biomonitoring strategies to better detect likely impacts of land use. We also identified a need for research to connect well-known causal elements in the RRV, such as climatic variables and hydrological alteration, to ecological effects. Our findings provide direction for future research and can aid in development of an adaptive management strategy for tributaries of the RRV.