Collaborative research skills should be meaningfully incorporated into undergraduate programmes

Scientific research has changed, now being largely conducted in collaborative teams. However, undergraduate student training has not necessarily kept pace with these changes. In order to work effectively in collaborative settings, students need to develop not only the technical skills related to their discipline, but also communication and interpersonal skills needed to work in teams. Nora J. Casson reports on research which proposes a model for explicitly teaching collaborative skills, while engaging students in meaningful scientific research. Skills such as managing data from multiple collaborators or giving and receiving feedback via file-sharing platforms should be taught as explicitly as traditional skills such as how to use a pipette or how to formulate a hypothesis

Hydrological and seasonal controls of phosphorus in Northern Great Plains agricultural streams

PostprintControls on nutrient transport in cold, low relief agricultural regions vary dramatically among seasons. The spring snowmelt is often the dominant runoff and nutrient loading event of the year. However, climate change may increase the proportion of runoff occurring with rainfall and there is an urgent need to understand seasonal controls on nutrient transport in order to understand how patterns may change in the future. In this study, we assess patterns and drivers of total phosphorus (TP) dynamics in eight streams draining agriculturally-dominated watersheds, located in southern Manitoba, Canada. Data from three years of monitoring revealed highly coherent patterns of TP concentrations in streams, with pronounced peaks in the spring and mid- summer across the region. This coherent pattern was in spite of considerable interannual variability in the magnitude and timing of discharge; in particular, a major storm event occurred in summer 2014, which resulted in more discharge than the preceding spring melt. Concentration-discharge model fits were generally poor or not significant, suggesting that runoff generation is not the primary driver of TP dynamics in the majority of streams. Seasonal patterns of conductivity and stream temperature suggest mechanisms controlling TP vary by season; a spring TP concentration maximum may be related to surface runoff over frozen soils while the summer TP maximum may be related to temperature-driven biogeochemical processes, which are not well-represented in current conceptual or predictive models. These findings suggest that controls on stream TP concentrations are dynamic through the year, and responses to increases in dormant and non-dormant season temperatures may depend on seasonally-variable processes

Untersuchungen von Beugesehnennähten mittels Bildsequenzanalyse im Experiment

Im Rahmen dieser Arbeit werden die Ergebnisse aus Zugversuchen an Schweinesehnen, die mit verschiedenen Nahtmaterialien und den gängigen Nahttechniken für Beugesehnen der Hand genäht wurden, vorgestellt. Schwerpunkt der Untersuchungen ist die Ermittlung und Dokumentation der Reißfestigkeit der Naht und die Spaltbildung an der Kontaktstelle der genähten Sehnenstümpfe mittels biomechanischer Versuche. Das Eintreten der Spaltbildung und des Nahtrisses wird durch videotechnische Aufzeichnungen, die den eigentlichen Messvorgang an der Universalprüfmaschine begleiten, exakt dokumentiert (Bildsequenzanalyse). Die Bildsequenzanalyse stellt gegenüber den in der Literatur dokumentierten Methoden eine wesentliche Fort- bzw. Neuentwicklung zur Ermittlung der Spaltstabilität und der Reißfestigkeit von genähten Sehnen dar. Die Auswertung der Versuche mittels Bildsequenzanalyse wurde für 12 verschiedene Nahttechnik/Nahtmaterial-Kombinationen durchgeführt. Nach Entwicklung und Anfertigung einer neuen Einspannvorrichtung für die Sehnen, die eine optimale Festhaltung der Sehnenstümpfe gewährleistete, erfolgte die systematische Durchführung von Bildsequenzanalysen für gängige Sehnennaht-Techniken mit verschiedenen Fäden. Auf Grundlage der biomechanischen Versuche und der Weiterentwicklung bisheriger Kenntnisse zur Beugesehnennaht konnte im Rahmen dieser Arbeit eine optimierte bzw. eine neue Nahttechnik entwickelt werden (Marburger Sehnennaht I und II), die eine frühe postoperative Mobilisierung durch entsprechende Nahtfestigkeiten ermöglicht, eine gute Gleitfunktion aufweist sowie durch Erhaltung der Gefäßversorgung der Sehne einen sicheren Heilungsprozess gewährleistet. Die Ergebnisse der biomechanischen Versuche mit der Marburger Sehnennaht I und II sind in dieser Arbeit detailliert dokumentiert. Der Vergleich mit den gängigen Sehnennaht-Techniken zeigt, dass die Marburger Sehnennaht eine hohe Reißfestigkeit und die beste Spaltstabilität besitzt

The ecology of methane in streams and rivers: patterns, controls, and global significance

Streams and rivers can substantially modify organic carbon (OC) inputs from terrestrial landscapes, and much of this processing is the result of microbial respiration. While carbon dioxide (CO₂) is the major end‐product of ecosystem respiration, methane (CH₄) is also present in many fluvial environments even though methanogenesis typically requires anoxic conditions that may be scarce in these systems. Given recent recognition of the pervasiveness of this greenhouse gas in streams and rivers, we synthesized existing research and data to identify patterns and drivers of CH₄, knowledge gaps, and research opportunities. This included examining the history of lotic CH4 research, creating a database of concentrations and fluxes (MethDB) to generate a global‐scale estimate of fluvial CH₄ efflux, and developing a conceptual framework and using this framework to consider how human activities may modify fluvial CH₄ dynamics. Current understanding of CH₄ in streams and rivers has been strongly influenced by goals of understanding OC processing and quantifying the contribution of CH₄ to ecosystem C fluxes. Less effort has been directed towards investigating processes that dictate in situ CH₄ production and loss. CH₄ makes a meager contribution to watershed or landscape C budgets, but streams and rivers are often significant CH₄ sources to the atmosphere across these same spatial extents. Most fluvial systems are supersaturated with CH₄ and we estimate an annual global emission of 26.8 Tg CH₄, equivalent to ~15‐40% of wetland and lake effluxes, respectively. Less clear is the role of CH₄ oxidation, methanogenesis, and total anaerobic respiration to whole ecosystem production and respiration. Controls on CH₄ generation and persistence can be viewed in terms of proximate controls that influence methanogenesis (organic matter, temperature, alternative electron acceptors, nutrients) and distal geomorphic and hydrologic drivers. Multiple controls combined with its extreme redox status and low solubility result in high spatial and temporal variance of CH₄ in fluvial environments, which presents a substantial challenge for understanding its larger‐scale dynamics. Further understanding of CH₄ production and consumption, anaerobic metabolism, and ecosystem energetics in streams and rivers can be achieved through more directed studies and comparison with knowledge from terrestrial, wetland, and aquatic disciplines."Support for this paper was provided by funding from the North Temperate Lakes LTER program, NSF DEB‐0822700."https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/15-102

The role of wetland coverage within the near-stream zone in predicting of seasonal stream export chemistry from forested headwater catchments

Postprint version. "This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record."Stream chemistry is often used to infer catchment‐scale biogeochemical processes. However, biogeochemical cycling in the near‐stream zone or hydrologically‐connected areas may exert a stronger influence on stream chemistry compared with cycling processes occurring in more distal parts of the catchment, particularly in dry seasons and in dry years. In this study, we tested the hypotheses that near‐stream wetland proportion is a better predictor of seasonal (winter, spring, summer and fall) stream chemistry compared with whole‐catchment averages and that these relationships are stronger in dryer periods with lower hydrologic connectivity. We evaluated relationships between catchment wetland proportion and 16‐year average seasonal flow‐weighted concentrations of both biogeochemically‐active nutrients, dissolved organic carbon (DOC), nitrate (NO3‐N), total phosphorus (TP), as well as weathering products, calcium (Ca), magnesium (Mg), at ten headwater (< 200 ha) forested catchments in south‐central Ontario, Canada. Wetland proportion across the entire catchment was the best predictor of DOC and TP in all seasons and years, whereas predictions of NO3‐N concentrations improved when only the proportion of wetland within the near‐stream zone was considered. This was particularly the case during dry years and dry seasons such as summer. In contrast, Ca and Mg showed no relationship with catchment wetland proportion at any scale or in any season. In forested headwater catchments, variable hydrologic connectivity of source areas to streams alters the role of the near‐stream zone environment, particularly during dry periods. The results also suggest that extent of riparian zone control may vary under changing patterns of hydrological connectivity. Predictions of biogeochemically‐active nutrients, particularly NO3‐N, can be improved by including near‐stream zone catchment morphology in landscape models.Funding for this project was provided by a Natural Sciences and Engineering Research Council of Canada Discovery Grant to MCE.https://onlinelibrary.wiley.com/doi/abs/10.1002/hyp.1341

Differences in atmospheric phosphorus deposition amongst rural and urban land use locations in Missouri

Atmospheric phosphorus (AP) produced by both anthropogenic and natural processes influences phytoplankton productivity and alters carbon processing in water bodies, resulting in potential impairment and toxic phytoplankton blooms. The production of AP, which is oftentimes transported vast distances by wind dispersal in the form of enriched mineral dust, can be re-deposited by wet (precipitation based) or dry (continual) deposition. Both rural and urban locations in Missouri experience varying anthropogenic activities; therefore, distinguishing between varying land use locations at these sites provides insight as to why AP may differ. The objective of this study is to determine if AP deposition differs among rural and urban land use locations in Missouri. When soil has been recently agitated and readily exposed, we hypothesize this additional P in the atmosphere will result in higher bulk deposition flux totals (BD) in rural locations. AP was collected from three rural locations and three urban locations, using a standard sized utility bucket, altered to reduce debris. After each two-week sampling period, a total sample water volume for each site is collected, total P is analyzed (TP), which determines the BD flux of each site by factoring the time it took to collect each sample (4 samples over approximately 70 days). Rural locations had the highest BD. Rural locations were not significantly different than urban locations (F5,18 = 1.667, p = 0.194). Further analysis of AP and the implication on water bodies is needed, as AP analysis is exceedingly rare. A multitude of differing land use practices results in variables that contribute significantly to the production of AP.Crystal Rein, Sarahi Viscarra Arellano, Karl Friesen-Hughes, Ashley King, Alexia Marten, Corey Sanderson, Jason J Venkiteswaran, Helen Baulch, Nora Jessie Casson, Colin J Whitfield, and Rebecca North (University of Missouri, University of Saskatchewan, Wilfrid Laurier University, University of Winnipeg

Hydrological and catchment controls on event-scale dissolved organic carbon dynamics in boreal headwater streams

Accepted version of manuscript.Hydrological events transport large proportions of annual or seasonal dissolved organic carbon (DOC) loads from catchments to streams. The timing, magnitude and intensity of these events are very sensitive to changes in temperature and precipitation patterns, particularly across the boreal region where snowpacks are declining and summer droughts are increasing. It is important to understand how landscape characteristics modulate event-scale DOC dynamics in order to scale up predictions from sites across regions, and to understand how climatic changes will influence DOC dynamics across the boreal forest. The goal of this study was to assess variability in DOC concentrations in boreal headwater streams across catchments with varying physiographic characteristics (e.g. size, proportion of wetland) during a range of hydrological events (e.g. spring snowmelt, summer/fall storm events). From 2016 to 2017, continuous discharge and sub-daily chemistry grab samples were collected from three adjacent study catchments located at the International Institute for Sustainable Development – Experimental Lakes Area in northwestern Ontario, Canada. Catchment differences were more apparent in summer and fall events and less apparent during early spring melt events. Hysteresis analysis suggested that DOC sources were proximal to the stream for all events at a catchment dominated by a large wetland near the outlet, but distal from the stream at the catchments that lacked significant wetland coverage during the summer and fall. Wetland coverage also influenced responses of DOC export to antecedent moisture; at the wetland-dominated catchment, there were consistent negative relationships between DOC concentrations and antecedent moisture, while at the catchments without large wetlands, the relationships were positive or not significant. These results emphasize the utility of sub-daily sampling for inferring catchment DOC transport processes, and the importance of considering catchment-specific factors when predicting event-scale DOC behaviour.https://onlinelibrary.wiley.com/doi/10.1002/hyp.14279?af=

GRiMeDB: the Global River Methane Database of concentrations and fluxes

Despite their small spatial extent, fluvial ecosystems play a significant role in processing and transporting carbon in aquatic networks, which results in substantial emission of methane (CH4) into the atmosphere. For this reason, considerable effort has been put into identifying patterns and drivers of CH4 concentrations in streams and rivers and estimating fluxes to the atmosphere across broad spatial scales. However, progress toward these ends has been slow because of pronounced spatial and temporal variability of lotic CH4 concentrations and fluxes and by limited data availability across diverse habitats and physicochemical conditions. To address these challenges, we present a comprehensive database of CH4 concentrations and fluxes for fluvial ecosystems along with broadly relevant and concurrent physical and chemical data. The Global River Methane Database (GriMeDB; https://doi.org/10.6073/pasta/f48cdb77282598052349e969920356ef, Stanley et al., 2023) includes 24 024 records of CH4 concentration and 8205 flux measurements from 5029 unique sites derived from publications, reports, data repositories, unpublished data sets, and other outlets that became available between 1973 and 2021. Flux observations are reported as diffusive, ebullitive, and total CH4 fluxes, and GriMeDB also includes 17 655 and 8409 concurrent measurements of concentrations and 4444 and 1521 fluxes for carbon dioxide (CO2) and nitrous oxide (N2O), respectively. Most observations are date-specific (i.e., not site averages), and many are supported by data for 1 or more of 12 physicochemical variables and 6 site variables. Site variables include codes to characterize marginal channel types (e.g., springs, ditches) and/or the presence of human disturbance (e.g., point source inputs, upstream dams). Overall, observations in GRiMeDB encompass the broad range of the climatic, biological, and physical conditions that occur among world river basins, although some geographic gaps remain (arid regions, tropical regions, high-latitude and high-altitude systems). The global median CH4 concentration (0.20 mu molL 1) and diffusive flux (0.44 mmolm 2 d 1) in GRiMeDB are lower than estimates from prior site-averaged compilations, although ranges (0 to 456 mu molL 1 and 136 to 4057 mmolm 2 d 1) and standard deviations (10.69 and 86.4) are greater for this larger and more temporally resolved database. Available flux data are dominated by diffusive measurements despite the recognized importance of ebullitive and plant-mediated CH4 fluxes. Nonetheless, GriMeDB provides a comprehensive and cohesive resource for examining relationships between CH4 and environmental drivers, estimating the contribution of fluvial ecosystems to CH4 emissions, and contextualizing site-based investigations

The role of wetland coverage within the near-stream zone in predicting of seasonal stream export chemistry from forested headwater catchments

Stream chemistry is often used to infer catchment-scale biogeochemical processes. However, biogeochemical cycling in the near-stream zone or hydrologically connected areas may exert a stronger influence on stream chemistry compared with cycling processes occurring in more distal parts of the catchment, particularly in dry seasons and in dry years. In this study, we tested the hypotheses that near-stream wetland proportion is a better predictor of seasonal (winter, spring, summer, and fall) stream chemistry compared with whole-catchment averages and that these relationships are stronger in dryer periods with lower hydrologic connectivity. We evaluated relationships between catchment wetland proportion and 16-year average seasonal flow-weighted concentrations of both biogeochemically active nutrients, dissolved organic carbon (DOC), nitrate (NO 3 -N), total phosphorus (TP), as well as weathering products, calcium (Ca), magnesium (Mg), at ten headwater (<200 ha) forested catchments in south-central Ontario, Canada. Wetland proportion across the entire catchment was the best predictor of DOC and TP in all seasons and years, whereas predictions of NO 3 -N concentrations improved when only the proportion of wetland within the near-stream zone was considered. This was particularly the case during dry years and dry seasons such as summer. In contrast, Ca and Mg showed no relationship with catchment wetland proportion at any scale or in any season. In forested headwater catchments, variable hydro

Internal phosphorus loading in Canadian freshwaters: A critical review and data analysis

Many physical, chemical, and biological processes in freshwater ecosystems mobilize the nutrient phosphorus (P) from sediments, which in turn, may contribute to the formation of harmful algal blooms. Here, we critically reviewed internal P loading in Canadian freshwaters to understand the geographic patterns and environmental drivers of this important process. From 43 publications, we consolidated 618 estimates of internal P loading from Canadian freshwater ponds, lakes, reservoirs, and coastal wetlands (n = 70). Expressed in terms of total phosphorus, short-term gross rates in sediment samples (Lgross) ranged from -27 to 54 mg m-2 d-1 (n = 461) while long-term net rates in whole-ecosystems (Lnet) ranged from -1694 to 10,640 mg m-2 y-1 (n = 157). The main environmental drivers of this variation were oxygen, pH, geology, and trophic state. Internal P loading tended to be higher during the open-water season, and most prominent in small prairie lakes. Priorities for future research on internal P loading should include resolving methodological problems, assessing the relative importance of different mechanisms, examining the influence of anthropogenic activities, and quantifying rates in under-studied ecosystems.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author