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    Looking back - looking forward: A novel multi-time slice weight-of-evidence approach for defining reference conditions to assess the impact of human activities on lake systems
    (Elsevier, 2018) Hollert, Henner; Crawford, Sarah E.; Brack, Werner; Brinkmann, Markus; Fischer, Elske; Hartmann, Kai; Keiter, Steffen; Ottermanns, Richard; Ouellet, Jacob; Rinke, Karsten; Roß-Nickoll, Martina; Schäffer, Andreas; Schüth, Christoph; Schulze, Tobias; Schwarz, Anja; Seiler, Thomas-Benjamin; Wessels, Martin; Hinderer, Matthias; Schwalb, Antje
    Lake ecosystems are sensitive recorders of environmental changes that provide continuous archives at annual to decadal resolution over thousands of years. The systematic investigation of land use changes and emission of pollutants archived in Holocene lake sediments as well as the reconstruction of contamination, background conditions, and sensitivity of lake systems offer an ideal opportunity to study environmental dynamics and consequences of anthropogenic impact that increasingly pose risks to human well-being. This paper discusses the use of sediment and other lines of evidence in providing a record of historical and current contamination in lake ecosystems. We present a novel approach to investigate impacts from human activities using chemical-analytical, bioanalytical, ecological, paleolimnological, paleoecotoxicological, archeological as well as modeling techniques. This multi-time slice weight-of-evidence (WOE) approach will generate knowledge on conditions prior to anthropogenic influence and provide knowledge to (i) create a better understanding of the effects of anthropogenic disturbances on biodiversity, (ii) assess water quality by using quantitative data on historical pollution and persistence of pollutants archived over thousands of years in sediments, and (iii) define environmental threshold values using modeling methods. This technique may be applied in order to gain insights into reference conditions of surface and ground waters in catchments with a long history of land use and human impact, which is still a major need that is currently not yet addressed within the context of the European Water Framework Directive.
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    Assessing the fate of brown trout (Salmo trutta) environmental DNA in a natural stream using a sensitive and specific dual-labelled probe
    (Elsevier, 2019) Deutschmann, Björn; Müller, Anne-Kathrin; Hollert, Henner; Brinkmann, Markus
    Environmental DNA (eDNA) analysis in the aquatic environment has emerged as a promising tool for diagnosis of the ecological status in comprehensive monitoring strategies and might become useful in context of the European Water Framework Directive (WFD) and other legislations to derive stressor-specific indicators. Despite many studies having made significant progress for the future use of eDNA in terms of ecosystem composition and detection of invasive/rare species in inland waters, much remains unknown about the transport and fate of eDNA under natural environmental conditions. We designed a specific dual-labelled probe to detect brown trout (Salmo trutta, L.) eDNA and used the probe to describe the fate of eDNA released from an aquaculture facility into the low mountain range stream Wehebach, Germany. The probe was shown to be specific to brown trout, as ponds housing rainbow trout (Oncorhynchus mykiss) did not test positive. Even though we observed different strengths of eDNA signals for three ponds containing different brown trout quantities, no significant correlation was found between biomass (kg/L) and eDNA quantity. Our results indicate that the release of DNA from brown trout might be life stage and/or age-dependent. The effluents of the aquaculture facility were a source of high levels of eDNA which resulted in the greatest abundance of brown trout eDNA directly downstream of the facility. Despite the natural occurrence of brown trout in the Wehebach, as shown by ecological investigations conducted by authorities of the federal state of North Rhine-Westphalia (Germany) and personal observations, we observed a significant decrease of relative abundance of eDNA in the Wehebach within the first 1.5 km downstream of the aquaculture. Our results suggest that concentrations of eDNA in running waters rapidly decrease under natural conditions due to dilution and degradation processes, which might have important implications for the utility of eDNA in environmental research.
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    Ecotoxicity of NSO-heterocycles (NSO-HET) and short-chained alkyl phenols (SCAP) commonly detected in contaminated groundwater
    (Society of Environmental Toxicology and Chemistry, 2019) Brinkmann, Markus; Schneider, Anna-Lena; Bluhm, Kerstin; Schiwy, Sabrina; Lehmann, Gunnar; Deutschmann, Björn; Müller, Axel; Tiehm, Andreas; Hollert, Henner
    Nitrogen, sulfur, or oxygen heterocyclic aromatic hydrocarbons (NSO-HETs) and short-chained alkyl phenols (SCAPs) are commonly detected in groundwater at contaminated sites and in the surrounding environment. It is now scientific consensus that these chemicals pose a risk to human and ecosystem health. However, toxicity data are comparably fragmentary, and only few studies have addressed the ecotoxicity of NSO-HETs and SCAPs in a systematic and comparative fashion. To overcome this shortcoming, we tested 18 SCAPs, 16 NSO-HETs, as well as the homocyclic hydrocarbons indane and indene in the Microtox® assay with Aliivibrio fischeri, the growth inhibition test with Desmodesmus subspicatus, the acute immobilization assay with Daphnia magna, as well as the fish embryo toxicity test with embryos of the zebrafish (Danio rerio). Because of the physicochemical properties of the tested chemicals (limited water solubility, volatility, and sorption to test vessels), actual exposure concentrations in test media and their dissipation over time were analytically quantified by means of gas chromatography with mass spectrometry. Analytically corrected effect levels (median effect and lethal concentrations) ranged from 0.017 to 180 mg L–1, underlining the environmental relevance of some NSO-HETs and SCAPs. Para-substituted phenols showed the overall greatest toxicities in all 4 toxicity tests. We provide, for the first time, a complete high-quality data set in support of better environmental risk assessments of these chemicals.
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    Bioactivation of Quinolines in a Recombinant Estrogen Receptor Transactivation Assay Is Catalyzed by N-Methyltransferases
    (ACS Publications, 2019) Brinkmann, Markus; Barz, Bogdan; Carrière, Danielle; Velki, Mirna; Smith, Kilian; Meyer-Alert, Henriette; Müller, Yvonne; Thalmann, Beat; Bluhm, Kersti; Schiwy, Sabrina; Hotz, Simone; Salowsky, Helena; Tiehm, Andreas; Hecker, Markus; Hollert, Henner
    Hydroxylation of polyaromatic compounds through cytochromes P450 (CYPs) is known to result in potentially estrogenic transformation products. Recently, there has been an increasing awareness of the importance of alternative pathways such as aldehyde oxidases (AOX) or N-methyltransferases (NMT) in bioactivation of small molecules, particularly N-heterocycles. Therefore, this study investigated the biotransformation and activity of methylated quinolines, a class of environmentally relevant N-heterocycles that are no native ligands of the estrogen receptor (ER), in the estrogen-responsive cell line ERα CALUX. We found that this widely used cell line overexpresses AOXs and NMTs while having low expression of CYP enzymes. Exposure of ERα CALUX cells to quinolines resulted in estrogenic effects, which could be mitigated using an inhibitor of AOX/NMTs. No such mitigation occurred after coexposure to a CYP1A inhibitor. A number of N-methylated but no hydroxylated transformation products were detected using liquid chromatography–mass spectrometry, which indicated that biotransformations to estrogenic metabolites were likely catalyzed by NMTs. Compared to the natural ER ligand 17β-estradiol, the products formed during the metabolization of quinolines were weak to moderate agonists of the human ERα. Our findings have potential implications for the risk assessment of these compounds and indicate that care must be taken when using in vitro estrogenicity assays, for example, ERα CALUX, for the characterization of N-heterocycles or environmental samples that may contain them.
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    A rapid and sensitive fluorometric method for determination of aldehyde oxidase activity
    (Elsevier, 2018) Apenova, Nancy; Peng, Hui; Hecker, Markus; Brinkmann, Markus
    Previous research has characterized the important role of aldehyde oxidases (AOX) in biotransformation of N-heterocyclic therapeutic drugs and environmental contaminants in mammals. Research pertaining to AOX activity in non-mammalian vertebrates, however, is scarce, despite its biological role as a potentially important metabolic pathway for xenobiotics. One of the limiting factors of research on AOX is that available photometric methods are relatively insensitive, limited in throughput, and prone to cross-reactivity from other enzymes. Therefore, this study aimed to develop a novel and improved fluorometric AOX assay. This assay is based on the conversion of the exogenous aldehyde substrate 4-(dimethyl)amino cinnamaldehyde to its corresponding fluorescent acid by AOX, and was evaluated using partially purified hepatic cytosol from rat, human, and rainbow trout. Purification of native cytosol by heat treatment and ammonium sulfate precipitation resulted in increased specific activity of AOX. Michaelis-Menten kinetic parameters (Km and Vmax) were comparable to values previously generated by photometric methods. Furthermore, effects of the inhibitor hydralazine on AOX activity revealed half maximal inhibitory concentrations comparable to those generated using conventional methods. Product identity was confirmed by liquid chromatography and mass spectrometry. In summary, this study successfully developed a rapid and sensitive assay for determination of AOX activity in across different vertebrate species that is 4- to 10-fold more sensitive compared to conventional absorbance-based methods. It can be applied in environmental, toxicological, and pharmacological studies relating to identification of AOX substrates, as well as the induction of AOX expression through drugs and environmental contaminants.
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    Above- and Below-Ground Carbon Sequestration in Shelterbelt Trees in Canada: A Review
    (MDPI, 2019) Mayrinck, Rafaella; Laroque, Colin; Amichev, Beyhan; Rees, Ken Van
    Shelterbelts have been planted around the world for many reasons. Recently, due to increasing awareness of climate change risks, shelterbelt agroforestry systems have received special attention because of the environmental services they provide, including their greenhouse gas (GHG) mitigation potential. This paper aims to discuss shelterbelt history in Canada, and the environmental benefits they provide, focusing on carbon sequestration potential, above- and below-ground. Shelterbelt establishment in Canada dates back to more than a century ago, when their main use was protecting the soil, farm infrastructure and livestock from the elements. As minimal-and no-till systems have become more prevalent among agricultural producers, soil has been less exposed and less vulnerable to wind erosion, so the practice of planting and maintaining shelterbelts has declined in recent decades. In addition, as farm equipment has grown in size to meet the demands of larger landowners, shelterbelts are being removed to increase efficiency and machine maneuverability in the field. This trend of shelterbelt removal prevents shelterbelt’s climate change mitigation potential to be fully achieved. For example, in the last century, shelterbelts have sequestered 4.85 Tg C in Saskatchewan. To increase our understanding of carbon sequestration by shelterbelts, in 2013, the Government of Canada launched the Agricultural Greenhouse Gases Program (AGGP). In five years, 27 million dollars were spent supporting technologies and practices to mitigate GHG release on agricultural land, including understanding shelterbelt carbon sequestration and to encourage planting on farms. All these topics are further explained in this paper as an attempt to inform and promote shelterbelts as a climate change mitigation tool on agricultural lands.
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    Green Spaces with Fewer People Improve Self-Reported Affective Experience and Mood
    (MDPI, 2023) Honey-Rosés, Jordi; Zapata, Oscar
    Calm and quiet green spaces provide health benefits for urban residents. Yet as cities become more densely populated, increasing public users to green spaces may reduce or moderate these benefits. We examine how increased pedestrian density in a green street changes self-reported wellbeing. We use a between subject experimental design that added public users as confederates in randomly selected periods over three weeks. We collect data on mood and affective response from pedestrians moving through the green street (n = 504), with and without our public user treatment in randomly selected periods. Mood and affective response are improved when experiencing the green street with fewer people. We find that an increased number of public users in the green space has a negative effect on mood, especially among women. We provide experimental evidence that self-reported wellbeing in urban green spaces depends on social context, and that there are gender inequities associated with changes in affective response. Although we only measure immediate impacts, our results imply that the health benefits of green spaces may be limited by the total number of users. This research contributes additional evidence that greener cities are also healthier cities, but that the benefits may not be equally shared between women and men and will depend on the social context of use.
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    Synthesis of magnetic metalorganic framework (MOF) for efficient removal of organic dyes from water
    (Nature Portfolio, 2015) Zhao, Xiaoli; Liu, Shuangliu; Tang, Zhi; Niu, Hongyun; Cai, Yaqi; Meng, Wei; Wu, Fengchang; Giesy, John
    A novel, simple and efficient strategy for fabricating a magnetic metal-organic framework (MOF) as sorbent to remove organic compounds from simulated water samples is presented and tested for removal of methylene blue (MB) as an example. The novel adsorbents combine advantages of MOFs and magnetic nanoparticles and possess large capacity, low cost, rapid removal and easy separation of the solid phase, which makes it an excellent sorbent for treatment of wastewaters. The resulting magnetic MOFs composites (also known as MFCs) have large surface areas (79.52 m2 g−1), excellent magnetic response (14.89 emu g−1), and large mesopore volume (0.09 cm3 g−1), as well as good chemical inertness and mechanical stability. Adsorption was not drastically affected by pH, suggesting π-π stacking interaction and/or hydrophobic interactions between MB and MFCs. Kinetic parameters followed pseudo-second-order kinetics and adsorption was described by the Freundlich isotherm. Adsorption capacity was 84 mg MB g−1 at an initial MB concentration of 30 mg L−1, which increased to 245 mg g−1 when the initial MB concentration was 300 mg L−1. This capacity was much greater than most other adsorbents reported in the literature. In addition, MFC adsorbents possess excellent reusability, being effective after at least five consecutive cycles.
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    High-resolution regional climate modeling and projection over western Canada using a weather research forecasting model with a pseudo-global warming approach
    (Published by Copernicus Publications on behalf of the European Geosciences Union, 2019) Li, Yanping; Li, Zhenhua; Zhang, Zhe; Chen, Liang; Kurkute, Sopan; Scaff, Lucia; Pan, Xicai
    Climate change poses great risks to western Canada’s ecosystem and socioeconomical development. To assess these hydroclimatic risks under high-end emission scenario RCP8.5, this study used theWeather Research Forecasting (WRF) model at a convection-permitting (CP) 4 km resolution to dynamically downscale the mean projection of a 19-member CMIP5 ensemble by the end of the 21st century. The CP simulations include a retrospective simulation (CTL, 2000–2015) for verification forced by ERA-Interim and a pseudo-global warming (PGW) for climate change projection forced with climate change forcing (2071–2100 to 1976–2005) from CMIP5 ensemble added on ERA-Interim. The retrospective WRF-CTL’s surface air temperature simulation was evaluated against Canadian daily analysis ANUSPLIN, showing good agreements in the geographical distribution with cold biases east of the Canadian Rockies, especially in spring. WRF-CTL captures the main pattern of observed precipitation distribution from CaPA and ANUSPLIN but shows a wet bias near the British Columbia coast in winter and over the immediate region on the lee side of the Canadian Rockies. The WRF-PGW simulation shows significant warming relative to CTL, especially over the polar region in the northeast during the cold season, and in daily minimum temperature. Precipitation changes in PGW over CTL vary with the seasons: in spring and late autumn precipitation increases in most areas, whereas in summer in the Saskatchewan River basin and southern Canadian Prairies, the precipitation change is negligible or decreased slightly. With almost no increase in precipitation and much more evapotranspiration in the future, the water availability during the growing season will be challenging for the Canadian Prairies. The WRF-PGW projected warming is less than that by the CMIP5 ensemble in all seasons. The CMIP5 ensemble projects a 10 %–20% decrease in summer precipitation over the Canadian Prairies and generally agrees with WRFPGW except for regions with significant terrain. This difference may be due to the much higher resolution of WRF being able to more faithfully represent small-scale summer convection and orographic lifting due to steep terrain. WRF-PGW shows an increase in high-intensity precipitation events and shifts the distribution of precipitation events toward more extremely intensive events in all seasons. Due to this shift in precipitation intensity to the higher end in the PGW simulation, the seemingly moderate increase in the total amount of precipitation in summer east of the Canadian Rockies may underestimate the increase in flooding risk and water shortage for agriculture. The change in the probability distribution of precipitation intensity also calls for innovative biascorrection methods to be developed for the application of the dataset when bias correction is required. High-quality meteorological observation over the region is needed for both forcing high-resolution climate simulation and conducting verification. The high-resolution downscaled climate simulations provide abundant opportunities both for investigating localscale atmospheric dynamics and for studying climate impacts on hydrology, agriculture, and ecosystems.
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    Toxic equivalency factors (TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife
    (National Institute of Environmental Health Sciences (NIEHS), 1998) Berg, Martin Van den; Birnbaum, Linda; Bosveld, Albertus T.C.; Brunstrom, Björn; Cook, Philip; Feely, Mark; Giesy, John; Hanberg, Annika; Hasegawa, Ryuichi; Kennedy, Sean W.; Kubiak, Timothy; Larsen, John Christian; Leeuwen, F.X. Rolaf van; Liem, A.K. Djien; Nolt, Cynthia; Peterson, Richard E.; Poellinger, Lorenz; Safe, Stephen; Schrenk, Dieter; Tillitt, Donald; Tysklind, Mats; Younes, Maged; Waern, Fredrik; Zacharewski, Tim
    An expert meeting was organized by the World Health Organization (WHO) and held in Stockholm on 15-18 June 1997. The objective of this meeting was to derive consensus toxic equivalency factors (TEFs) for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and dioxinlike polychlorinated biphenyls (PCBs) for both human, fish, and wildlife risk assessment. Based on existing literature data, TEFs were (re)evaluated and either revised (mammals) or established (fish and birds). A few mammalian WHO-TEFs were revised, including 1,2,3,7,8-pentachlorinated DD, octachlorinated DD, octachlorinated DF, and PCB 77. These mammalian TEFs are also considered applicable for humans and wild mammalian species. Furthermore, it was concluded that there was insufficient in vivo evidence to continue the use of TEFs for some di-ortho PCBs, as suggested earlier by Ahlborg et al. [Chemosphere 28:1049-1067 (1994)]. In addition, TEFs for fish and birds were determined. The WHO working group attempted to harmonize TEFs across different taxa to the extent possible. However, total synchronization of TEFs was not feasible, as there were orders of a magnitude difference in TEFs between taxa for some compounds. In this respect, the absent or very low response of fish to mono-ortho PCBs is most noticeable compared to mammals and birds. Uncertainties that could compromise the TEF concept were also reviewed, including nonadditive interactions, differences in shape of the dose-response curve, and species responsiveness. In spite of these uncertainties, it was concluded that the TEF concept is still the most plausible and feasible approach for risk assessment of halogenated aromatic hydrocarbons with dioxinlike properties.
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    Soil and water management: opportunities to mitigate nutrient losses to surface waters in the Northern Great Plains
    (Canadian Science Publishing, 2019) Baulch, Helen; Elliott, Jane; Cordeiro, Marcos; Flaten, Don N.; Lobb, David; Wilson, Henry
    The Northern Great Plains is a key region to global food production. It is also a region of water stress that includes poor water quality associated with high concentrations of nutrients. Agricultural nitrogen and phosphorus loads to surface waters need to be reduced, yet the unique characteristics of this environment create challenges. The biophysical reality of the Northern Great Plains is one where snowmelt is the major period of nutrient transport, and where nutrients are exported predominantly in dissolved form. This limits the efficacy of many beneficial management practices (BMPs) commonly used in other regions and necessitates place-based solutions. We discuss soil and water management BMPs through a regional lens—first understanding key aspects of hydrology and hydrochemistry affecting BMP efficacy, then discussing the merits of different BMPs for nutrient control. We recommend continued efforts to “keep water on the land” via wetlands and reservoirs. Adoption and expansion of reduced tillage and perennial forage may have contributed to current nutrient problems, but both practices have other environmental and agronomic benefits. The expansion of tile and surface drainage in the Northern Great Plains raises urgent questions about effects on nutrient export and options to mitigate drainage effects. Riparian vegetation is unlikely to significantly aid in nutrient retention, but when viewed against an alternative of extending cultivation and fertilization to the waters’ edge, the continued support of buffer strip management and refinement of best practices (e.g., harvesting vegetation) is merited. While the hydrology of the Northern Great Plains creates many challenges for mitigating nutrient losses, it also creates unique opportunities. For example, relocating winter bale-grazing to areas with low hydrologic connectivity should reduce loadings. Managing nutrient applications must be at the center of efforts to mitigate eutrophication. In this region, ensuring nutrients are not applied during hydrologically sensitive periods such as late autumn, on snow, or when soils are frozen will yield benefits. Working to ensure nutrient inputs are balanced with crop demands is crucial in all landscapes. Ultimately, a targeted approach to BMP implementation is required, and this must consider the agronomic and economic context but also the biophysical reality.
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    Our failure to protect the stream and its valley: A call to back off from riparian development
    (The University of Chicago Press, 2022) Cooke, Steven; Vermaire, Jesse; Baulch, Helen; Birnie-Gauvin, Kim; Twardek, William; Richarson, John S.
    Decades ago, Dr Noel Hynes eloquently summarized the inherent interconnectedness of a stream and its valley and made the case that human alteration of the valley would have direct negative consequences for freshwater systems. Currently, the freshwater biodiversity crisis extends across all continents and demands urgent attention from environmental planners, practitioners, and policymakers to protect streams and their valleys. As we work to slow losses of freshwater biodiversity and restore freshwater ecosystems, it is time to revisit the important messages from Hynes. One of the most obvious and immediate actions that could be undertaken is to “back off”—that is, to limit human activity and new development in floodplain and riparian areas immediately adjacent to freshwater systems, including streams, rivers, lakes, and wetlands, while minimizing impacts and risks in areas with existing development. From reducing erosion and flood damage to maintaining cool water temperatures, filtering pollutants, protecting critical habitats, and enabling lateral connectivity, intact riparian zones mitigate many of the threats that degrade freshwater ecosystems. There has been much research to identify optimal setbacks and buffer-strip widths to protect against harm. As such, in many areas, our ability to protect the stream and its valley is not limited by natural science but rather our failure to consistently apply floodplain and riparian regulations and the absence of political will. We are too quick to trade off the environment for short-term economic development. In areas that are already developed, solutions are more complicated but, in many cases, represent a key priority for healing damaged ecosystems and for addressing economic and social risks of vulnerable development. We need to redefine our relationship with freshwater ecosystems, and the first step is to back off and give freshwater ecosystems the opportunity to heal while ensuring that as-of-yet intact riparian areas continue to support freshwater resiliency. In doing so, we will also gain climate adaptive benefits, given that maintaining intact riparian areas is an effective nature-based solution.
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    Winter in two phases: Long-term study of a shallow reservoir in winter
    (Wiley [Commercial Publisher], Association for the Sciences of Limnology and Oceanography (ASLO) [Society Publisher], 2020) Cavaliere, Emily; Baulch, Helen
    Climate-driven decreases in ice-cover duration have the potential to impact lake ecosystems, yet we have only partial understanding of the effects of winter conditions on physical, chemical, and biological properties of lakes. We used 39 years of monitoring data to examine under-ice changes in nutrients, oxygen, and phytoplankton in a shallow drinking-water reservoir. Two phases of winter were identified. Early winter was characterized by declining oxygen. In this phase, there were increases in specific conductance and concentrations of ammonium (NH4+-N) and soluble reactive phosphorus (SRP). In the month prior to ice off these trends reversed themselves and phytoplankton began to increase. Specific conductance declined as meltwater entered the lake. Nutrients (SRP and NH4+-N) declined, concurrent with increases in chlorophyll a and oxygen during late winter. This work demonstrates that chemical and biotic changes through winter are highly time dependent and differ between early and late winter phases. The late winter phase is often unstudied because of unsafe ice conditions, but here, the “spring” bloom commonly occurs in late winter under ice. The phases of winter, which are likely driven by changes in light, must be considered as we work to understand how diverse lakes will respond to declining periods of ice cover, and what drives differences in the spring ecology of diverse ice-covered lakes.
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    Seasonal variability of CO2, CH4, and N2O content and fluxes in small agricultural reservoirs of the northern Great Plains
    (Frontiers Media, 2022) Jensen, Sydney; Webb, Jackie; Simpson, Gavin; Baulch, Helen; Leavitt, Peter; Finlay, Kerri
    Inland waters are important global sources, and occasional sinks, of CO2, CH4, and N2O to the atmosphere, but relatively little is known about the contribution of GHGs of constructed waterbodies, particularly small sites in agricultural regions that receive large amounts of nutrients (carbon, nitrogen, phosphorus). Here, we quantify the magnitude and controls of diffusive CO2, CH4, and N2O fluxes from 20 agricultural reservoirs on seasonal and diel timescales. All gases exhibited consistent seasonal trends, with CO2 concentrations highest in spring and fall and lowest in mid-summer, CH4 highest in mid-summer, and N2O elevated in spring following ice-off. No discernible diel trends were observed for GHG content. Analyses of GHG covariance with potential regulatory factors were conducted using generalized additive models (GAMs) that revealed CO2 concentrations were affected primarily by factors related to benthic respiration, including dissolved oxygen (DO), dissolved inorganic nitrogen (DIN), dissolved organic carbon (DOC), stratification strength, and water source (as δ18Owater). In contrast, variation in CH4 content was correlated positively with factors that favoured methanogenesis, and so varied inversely with DO, soluble reactive phosphorus (SRP), and conductivity (a proxy for sulfate content), and positively with DIN, DOC, and temperature. Finally, N2O concentrations were driven mainly by variation in reservoir mixing (as buoyancy frequency), and were correlated positively with DO, SRP, and DIN levels and negatively with pH and stratification strength. Estimates of mean CO2-eq flux during the open-water period ranged from 5,520 mmolm−2 year1 (using GAM-predictions) to 10,445 mmolm−2 year−1 (using interpolations of seasonal data) reflecting how extreme values were extrapolated, with true annual flux rates likely falling between these two estimates.
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    Blooms and flows: Effects of variable hydrology and management on reservoir water quality
    (Wiley Open Access (Commercial Publisher); Ecological Society of America (Society Publisher), 2023) Painter, Kristin; Venkiteswaran, Jason J.; Baulch, Helen
    Flow management has the potential to significantly affect ecosystem condition. Shallow lakes in arid regions are especially susceptible to flow management changes, which can have important implications for the formation of cyanobacterial blooms. Here, we reveal water quality shifts associated with changing source water inflow management. Using in situ monitoring data, we studied a seven-year time span during which inflows to a shallow, eutrophic drinking water reservoir transitioned from primarily natural landscape runoff (2014–2015) to managed flows from a larger upstream reservoir (Lake Diefenbaker; 2016–2020) and identified significant changes in cyanobacteria (as phycocyanin) using generalized additive models to classify cyanobacterial bloom formation. We then connected changes in water source with shifts in chemistry and the occurrence of cyanobacterial blooms using principal components analysis. Phycocyanin was greater in years with managed reservoir inflow from a mesotrophic upstream reservoir (2016–2020), but dissolved organic matter (DOM) and specific conductivity, important determinants of drinking water quality, were greatest in years when landscape runoff dominated lake water source (2014–2015). Most notably, despite changing rapidly, it took multiple years for lake water to return to a consistent and reduced level of DOM after managed inflows from the upstream reservoir were resumed, an observation that underscores how resilience may be hindered by weak resistance to change and slow recovery. Environmental flows for water quality are rarely defined, yet we show that trade-offs exist between poor water quality via elevated conductivity and DOM and higher bloom risk, depending on water source. Our work highlights the importance of source water quality, not just quantity, to water security, and our findings have important implications for water managers who must protect ecosystem services while adapting to projected hydroclimatic change.
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    Differential Controls of Greenhouse Gas (CO2, CH4, and N2O) Concentrations in Natural and Constructed Agricultural Waterbodies on the Northern Great Plains
    (American Geophysical Union (Client Organisation), Wiley (Commercial Publisher), 2023) Jensen, Sydney; Webb, Jackie; Simpson, Gavin; Baulch, Helen; Leavitt, Peter; Finlay, Kerri
    Inland waters are hotspots of greenhouse gas (GHG) cycling, with small water bodies particularly active in the production and consumption of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). However, wetland ponds are being replaced rapidly by small constructed reservoirs in agricultural regions, yet it is unclear whether these two water body types exhibit similar physical, chemical, and environmental controls of GHG content and fluxes. Here, we compared the content and regulatory mechanisms of all three major GHGs in 20 pairs of natural wetland ponds and constructed reservoirs in Canada's largest agricultural region. Carbon dioxide content was associated primarily with metabolic indicators in both water body types; however, primary production was paramount in reservoirs, and heterotrophic metabolism a stronger correlate in wetland ponds. Methane concentrations were correlated positively with eutrophication of the reservoirs alone, while competitive inhibition by sulfur-reducing bacteria may have limited CH4 in both waterbody types. Contrary to expectations, N2O was undersaturated in both water body types, with wetlands being a significantly stronger and more widespread N2O sink. Varying regulatory processes are attributed to differences in age, depth, morphology, and water-column circulation between water body types. These results suggest that natural and constructed water bodies should be modeled separately in regional GHG budgets.
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    Applying a two-dimensional hydrodynamic model to estimate fish stranding risk downstream from a hydropeaking hydroelectric station
    (Wiley Online Library, 2023) Glowa, Sarah; Kneale, Andrea; Watkinson, Douglas A.; Ghamry, Haitham K.; Enders, Eva; Jardine, Timothy
    Fish stranding is of global concern with increasing hydropower operations using hydropeaking to respond to fluctuating energy demand. Determining the effects hydropeaking has on fish communities is challenging because fish stranding is dependent on riverscape features, such as topography, bathymetry and substrate. By using a combination of physical habitat assessments, hydrodynamic modelling and empirical data on fish stranding, we estimated the number of fish stranding over a 5-month period for three model years in a large Prairie river. More specifically, we modelled how many fish potentially stranded during the years 2019, 2020 and 2021 across a 16 km study reached downstream from E.B. Campbell Hydroelectric Station on the Saskatchewan River, Canada. Fish stranding densities calculated from data collected through remote photography and transect monitoring in 2021 were applied to the daily area subject to drying determined by the River2D hydrodynamic model. The cumulative area subject to change was 90.05, 53.02 and 80.74 km2 for years 2019, 2020 and 2021, respectively, from June to October. The highest number of stranded fish was estimated for the year 2021, where estimates ranged from 89,800 to 1,638,000 individuals based on remote photography and transect monitoring fish stranding densities, respectively, 157 to 2,856 fish stranded per hectare. Our approach of estimating fish stranding on a large scale allows for a greater understanding of the impact hydropeaking has on fish communities and can be applied to other riverscapes threatened by hydropeaking.Fish stranding is of global concern with increasing hydropower operations using hydropeaking to respond to fluctuating energy demand. Determining the effects hydropeaking has on fish communities is challenging because fish stranding is dependent on riverscape features, such as topography, bathymetry and substrate. By using a combination of physical habitat assessments, hydrodynamic modelling and empirical data on fish stranding, we estimated the number of fish stranding over a 5-month period for three model years in a large Prairie river. More specifically, we modelled how many fish potentially stranded during the years 2019, 2020 and 2021 across a 16 km study reached downstream from E.B. Campbell Hydroelectric Station on the Saskatchewan River, Canada. Fish stranding densities calculated from data collected through remote photography and transect monitoring in 2021 were applied to the daily area subject to drying determined by the River2D hydrodynamic model. The cumulative area subject to change was 90.05, 53.02 and 80.74 km2 for years 2019, 2020 and 2021, respectively, from June to October. The highest number of stranded fish was estimated for the year 2021, where estimates ranged from 89,800 to 1,638,000 individuals based on remote photography and transect monitoring fish stranding densities, respectively, 157 to 2,856 fish stranded per hectare. Our approach of estimating fish stranding on a large scale allows for a greater understanding of the impact hydropeaking has on fish communities and can be applied to other riverscapes threatened by hydropeaking.
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    Evaluating the risk of fish stranding due to hydropeaking in a large continental river
    (Wiley Online Library, 2022) Glowa, Sarah; Watkinson, Douglas A.; Jardine, Timothy; Enders, Eva
    With the continuous development of hydropower on a global scale, stranding of freshwater fishes is of growing concern, and an understanding of the mechanisms and variables affecting fish stranding in hydropeaking rivers is urgently needed. In particular, a methodology is required to identify the magnitude and timing at which fish stranding occurs in relation to environmental conditions. Here, we studied fish stranding in three reaches downstream of a hydropeaking generation station in the Saskatchewan River, Saskatchewan, Canada, using an innovative remote photography approach with 45 trail cameras and traditional transect monitoring, conducting 323 transects. We observed that juvenile sport and commercial fish species are stranding at a higher proportion than small bodied fish species. The remote photography approach provided more precise fish stranding timing and associated the environmental and physical conditions with a given stranding event, but captured fewer fish and only rarely allowed species identification. The comparison of the two methodologies resulted in similar stranded fish densities, but the remote photography allowed for continuous observations whereas the transect monitoring was limited by the observer availability in the field. Remote photography allowed for additional information on the scavenging of stranded fish, with scavenging occurring on average within 240 minutes of the fish being stranded. The probability of fish stranding increased significantly with increasing water temperature and substrate particle size resulted in greater stranding on finer substrates. Our findings have important implications for hydroelectric flow management by introducing an innovative, standardized method to study the effects of hydropeaking events on fish stranding that can be applied to increase our understanding of the impacts of hydropeaking on fish communities.
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    Dietary shifts may underpin the recovery of a large carnivore population
    (Biology Letters, 2022) Campbell, Mariana A.; Udyawer, Vinay; Jardine, Timothy; Fukuda, Yusuke; Kopf, R. Keller; Bunn, Stuart; Campbell, Hamish
    Supporting the recovery of large carnivores is a popular yet challenging endeavour. Estuarine crocodiles in Australia are a large carnivore conservation success story, with the population having extensively recovered from past heavy exploitation. Here, we explored if dietary changes had accompanied this large population recovery by comparing the isotopes δ13C and δ15N in bones of crocodiles sampled 40 to 55 years ago (small population) with bones from contemporary individuals (large population). We found that δ13C and δ15N values were significantly lower in contemporary crocodiles than in the historical cohort, inferring a shift in prey preference away from marine and into terrestrial food webs. We propose that an increase in intraspecific competition within the recovering crocodile population, alongside an increased abundance of feral ungulates occupying the floodplains, may have resulted in the crocodile population shifting to feed predominantly upon terrestrial food sources. The number of feral pigs consumed to sustain and grow crocodile biomass may help suppress pig population growth and increase the flow of terrestrially derived nutrients into aquatic ecosystems. The study highlights the significance of prey availability in contributing to large carnivore population recovery.
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    Comparative analysis of cadmium uptake and distribution in contrasting canadian flax cultivars
    (BMC, 2020) House, Megan; Young, Lester W.; Liu, Xia; Liber, Karsten; Diederichsen, Axel; Booker, Helen
    Objective: Humans consume low quantities of cadmium (Cd), a non-nutritive and potentially toxic heavy metal, primarily via the dietary intake of grains. A trial experiment was conducted to investigate physiological and developmental differences in Cd content in four flax cultivars (‘AC Emerson’, ‘Flanders’, ‘CDC Bethune’, and ‘AC McDuff’) as part of a study to provide information that will assist in the breeding of low Cd-accumulating flax cultivars. Our objective was to identify varietal differences in the uptake and distribution of Cd in various tissues among flax cultivars grown in naturally Cd-containing soil in a controlled environment. Results: Cadmium concentration was dependent on genotype, developmental stage, and tissue type, as well as their interaction. Cadmium concentration was higher in roots and leaves, relative to all other tissues, with a general trend of decreasing Cd content over time within leaves and stems. Notably, the concentration of Cd was higher in ‘AC Emerson’ relative to ‘AC McDuff’ across tissues and ages, including the seeds, while the concentration of ‘Flanders’ was higher than in ‘AC McDuff’ in seeds and other reproductive organs but similar in roots and leaves. The results suggest varietal differences in the mechanisms that determine Cd content in seeds.