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- OPEN ACCESSTadpoles are important prey items for many aquatic organisms and often represent the largest vertebrate biomass in many fishless wetland ecosystems. Neurotoxic mercury (Hg) can, at elevated levels, decrease growth, lower survival, and cause developmental instability in amphibians. We compared total Hg (THg) body burden and concentration in boreal chorus frog (Pseudacris maculata) and wood frog (Rana sylvatica) tadpoles. Overall, body burden and concentration were lower in boreal chorus frog tadpoles than wood frog tadpoles, as expected, because boreal chorus frog tadpoles consume at lower trophic levels. The variables species, stage, and mass explained 21% of total variation for body burden in our models but had negligible predictive ability for THg concentration. The vast majority of the remaining variation in both body burden and THg concentration was attributable to differences among ponds; tadpoles from ponds in three areas had considerably higher THg body burden and concentration. The pond-to-pond differences were not related to any water chemistry or physical parameter measured, and we assumed that differences in wetland geomorphology likely played an important role in determining Hg levels in tadpoles. This is the first report of Hg in frog tadpoles in the Prairie Pothole Region of North America.
- OPEN ACCESSOceanic circulation patterns shape both the distribution of species and spatial patterns of intraspecific genetic variation by influencing passively dispersed marine invertebrates. In the northwest Atlantic, strong and consistent currents at the mouth of the Bay of Fundy are expected to restrict dispersal in this region, but the relationship between populations of high dispersal species along the surrounding coastal regions has been largely underrepresented in the phylogeographic literature. We analyzed phylogeographic patterns in two intertidal invertebrates with high dispersal abilities, Tritia obsoleta (Mollusca: Gastropoda) and Macoma petalum (Mollusca: Bivalvia), between Cape Cod and the Gulf of St. Lawrence using mitochondrial DNA (mtDNA). Hierarchical analysis of molecular variance revealed population structuring among regions defined by circulation patterns, highly divergent lineages within M. petalum, and strong concordant genetic subdivision in both species between the Bay of Fundy and Gulf of Maine. Our results suggest that the gyre at the mouth of the bay is influential in restricting alongshore dispersal, allowing genetic divergence between regions to arise through genetic drift. These findings are concordant with biogeographic and phylogeographic studies of other marine organisms, suggesting that the genetic isolation of widely distributed species may be a common feature of intertidal invertebrate communities in the Bay of Fundy.
- OPEN ACCESSAn ordinary differential equation describing the transverse profiles of U-shaped glacial valleys has two formal analogies, which we explore in detail, bridging these different areas of research. First, an analogy with point particle mechanics completes the description of the solutions. Second, an analogy with the Friedmann equation of relativistic cosmology shows that the analogue of a glacial valley profile is a universe with a future singularity of interest in theoretical models of cosmology. A Big Freeze singularity, which was not previously observed for positive curvature index, is also contained in the dynamics.
- OPEN ACCESSOften the Before-After-Control-Impact (BACI) design is suggested as being a statistically powerful experimental design in environmental impact studies. If the timing and location of the impact are known and adequate pre-data are collected, the BACI design is considered optimal to help isolate the effect of the development from natural variability. This paper presents 9 years of results from a long-term BACI experiment tested using a range of statistical models and post-impact monitoring designs. To explore suboptimal designs that are often utilized in environmental effects monitoring, the same data were also explored assuming either no control system was available (Before-After only), or that no pre-impact data were available (Control-Impact only). The results of the BACI design were robust to the statistical model used, and the BACI design was able to detect effects from the impact that the two suboptimal designs failed to detect. However, the BACI design demonstrated different conclusions depending on the number and configuration of post-impact years included in the analysis. Our results reinforce the idea that caution should be employed when using, or interpreting results from, a BACI design in an environmental impact study, but demonstrate that a well-designed BACI remains one of the best models for environmental effects monitoring programs.
- OPEN ACCESSAmmonium deposition at the International Institute for Sustainable Development Experimental Lakes Area (IISD–ELA), in northwestern Ontario, Canada, has doubled in the last 45 years and thus is no longer among the low nitrogen (N) deposition sites in North America. This may be related to the concurrent intensification of Manitoba agriculture to the west and upwind of the ELA. Large increases in ammonium deposition at the ELA were important in driving the observed trend and increased the NH4 + to NO3 − ratio of input to aquatic and terrestrial systems. Stable isotope analyses of two years of bulk (wet and dry) atmospheric deposition revealed very large ranges in δ15N−NH4 + (22‰ range), δ15N−NO3 − (18‰), and δ18O–NO3 − (19‰). Few other δ15N−NH4 +, δ15N−NO3 −, and δ18O–NO3 − values have been published for Canadian precipitation. Increases in δ15N of NH4 + and NO3 − in July occurred with increases in total N deposition. The wide range and seasonal trends of δ15N and δ18O values in ELA precipitation mean that studies characterizing N inputs to watersheds and lakes require an ongoing and comprehensive annual sampling regime. Global trends of declining δ15N of N deposition evident in lake sediment records may be a result of increases in NH4 + deposition with lower δ15N−NH4 + values. Similarly, the relationship in Lake Superior between increasing NO3 − and lower δ15N−NO3 − values may be explained by increased atmospheric deposition of N with low δ15N values.
- OPEN ACCESSA reliable marker of early coral response to environmental stressors can help guide decision-making to mitigate global coral reef decline by detecting problems before the development of clinically observable disease. We document the accumulation of acrylic acid in two divergent coral taxa, stony small polyp coral (Acropora sp.) and soft coral (Lobophytum sp.), in response to deteriorating water quality characterized by moderately increased ammonia (0.25 ppm) and phosphate (0.15 ppm) concentrations and decreased calcium (360 ppm) concentration, using nuclear magnetic resonance spectroscopy (NMR)-based metabolomic techniques. Changes in acrylic acid concentration in polyp tissues free of zooxanthellae suggest that acrylic acid could be a product of animal metabolism and not exclusively a metabolic by-product of the osmolyte dimethylsulfoniopropionate (DMSP) in marine algae or bacteria. Our findings build on previously documented depletions of acrylic acid in wild coral potentially correlated to temperature stress and provide additional insight into approaches to further characterize the nature of the metabolic accumulation of acrylic acid under controlled experimental conditions.
- OPEN ACCESSMicroplastic pollution is prevalent in the Ottawa River, with all open water samples (n = 62) and sediment samples (n = 10) containing microplastics. The median microplastic concentration of nearshore 100 L water samples was 0.1 fragments per L (ranged between 0.05 and 0.24 fragments per L). The larger volume Manta trawls samples taken in the middle of the Ottawa River had an overall mean concentration of plastics of 1.35 fragments per m3. Plastic concentrations were significantly higher downstream of the wastewater treatment plant (1.99 fragments per m3) compared with upstream of the effluent output (0.71 fragments per m3), suggesting that the effluent plume is a pathway for plastic pollution to the Ottawa River. The mean concentration of microplastic fragments recovered in the sediment samples was 0.22 fragments per g dry weight. The abundance of microplastics in the sediment was not significantly related to the mean particle size or the organic content of the sediment. The most common form of plastic particles found was microfibers. These made up between 70% and 100% of all plastic particles observed, although plastic microbeads and secondary plastic fragments were also recovered.
- OPEN ACCESSOrnithomimid material from the Belly River Group (Campanian) of Alberta, Canada is described as sharing characters with Qiupalong henanensis from the Qiupa Formation of Henan Province, China. Derived characters and character combinations of the pubis and astragalocalcaneum were previously used to diagnose Q. henanensis and support the referral of this material to Qiupalong sp., representing the first known occurrences of Qiupalong outside of China. Qiupalong is the sixth ornithomimid taxon to be reported from the Dinosaur Park Formation and the first ornithomimid genus with a transcontinental distribution. The Alberta material represents the oldest known occurrences of Qiupalong, and a reconsideration of character evidence suggests that this genus is phylogenetically nested within other North American ornithomimids. A North American origin for Qiupalong and subsequent dispersal to Asia is proposed.
- OPEN ACCESS
- Dewey W. Dunnington,
- Hilary White,
- Ian S. Spooner,
- Mark L. Mallory,
- Chris White,
- Nelson J. O’Driscoll, and
- Nic R. McLellan
We used a paleolimnological approach at Long Lake, Nova Scotia, to construct a 10 500-year record of metal deposition in lakebed sediments and elucidate the influence of both natural and anthropogenic environmental changes. Aquatic sediment concentrations of mercury (Hg), arsenic (As), and chromium (Cr) in Long Lake fluctuated substantially and, during some periods, exceeded guidelines for the protection of aquatic life. Increases in lead (Pb), Hg, Cr, trace metals, and nitrogen stable isotopes (δ15N) were broadly coincident with a period of widespread drying from ca. 8000 to 4000 cal BP and were likely a consequence of regional fires. From ca. 4000 cal BP until 1700 AD, metal levels in general were low due to decreased erosion, increased precipitation, and reduced fire activity. Water level lowering and forced sediment aggradation (tiding) in the 1800s led to increases in minerogenic Pb and Cr, though fossil fuel combustion also likely contributed to total Pb concentrations. Stratigraphic proxies indicated increased inorganic sedimentation rates, and reduced autochthonous productivity were coincident with lower Hg and As concentrations in the Long Lake sediment. Our data indicate that natural phenomena (fire) can result in sediment contaminant exceedances, that most metals have multiple sources, and that both human-induced disturbance and emissions have contributed to Pb contamination in the last 200 years. In addition, wetter and generally cooler climate appeared to favour lower concentrations of contaminants in lake sediments. Although wetland sediments in the Cumberland Basin Marshes are not heavily polluted with metals, the development of constructed wetlands and the disruption of aquatic sediments have the potential to concentrate, mobilize, and increase the bioavailability of metals. - OPEN ACCESSLife history theory predicts selection for higher reproductive investment in response to increased mortality among mature individuals. We tested this prediction over the period from 1978 to 2013 for three populations of Atlantic cod (Gadus morhua) off Newfoundland. These populations were heavily fished for a long period. We considered changes in standardized gonad weight as a proxy for changes in gonadal investment. We accounted for the allometry between gonad and body weight, individual body condition, water temperature, and potential spatial and density-dependent effects. Males display significant temporal trends in gonadal investment in all populations; in agreement with theoretical predictions, these trends show increased gonadal investments during the earlier part of the time series when mortality was high, with the trends leveling off or reversing after the later imposition of fishing moratoria. In contrast, females display patterns that are less consistent and expected; significant trends are detected only when accounting for density-dependent effects, with females in two populations unexpectedly showing a long-term decline in gonadal investment. Our results support the hypothesis that fisheries-induced evolution has occurred in gonadal investment in males, but not in females, and suggest that gonadal investment is more important for male reproductive success than expected in this lekking species.
- OPEN ACCESSMicroplastics are defined as any plastic with a diameter ≤5 mm. Problems associated with these plastics such as contamination of both marine and freshwater environments and ingestion by aquatic organisms are of increasing concern. Our study quantifies the number of microplastics in a prairie creek immediately downstream of Regina, Saskatchewan, Canada. Water samples and five species of fish were collected from sample sites upstream and downstream of a wastewater treatment plant (WWTP) in the summers of 2015 and 2016. Samples were digested in either a Fe(II)/H2O2 or NaClO solution and observed under a microscope where plastics present were enumerated by colour and type. At least one microplastic was detected in 73.5% of fish and 95.6% of water samples, showing that the creek does, in fact, contain microplastics. Concentrations were higher in water from upstream sites, likely due to dilution of creek water by the release of treated effluent. The results of this study provide baseline conditions for the presence of plastics in the creek prior to a major upgrade of the WWTP scheduled for completion in 2016.
- OPEN ACCESSThere has been a significant increase in the rate of felt earthquakes in western Alberta and eastern British Columbia, which has been associated with hydraulic fracturing and wastewater disposal. The increased rate of seismicity and the potential for localized strong ground motions from very shallow events poses an increased hazard to critical infrastructure such as major dams—particularly for older high-consequence structures. This paper overviews the factors that affect the likelihood of damaging ground motions and examines their implications for hazard assessment and mitigation. A strategy aimed at reducing the likelihood of potentially damaging ground motions to achieve probabilistic targets for critical facilities is developed, comprising elements of both mitigation and avoidance. For critical facilities, an effective strategy includes (i) an exclusion zone having a radius of ∼5 km; and (ii) a monitoring-and-response protocol to track the rate of events at the M > 2 level within 25 km, with adjustment of operational practices if required. An exclusion zone provides a deterministic safety margin to ensure the integrity of those few facilities for which failure consequences are unacceptable. Real-time monitoring tied to a response protocol can be used to control the rate of significant events and thereby limit the hazard more broadly.
- OPEN ACCESS
- Ben J.G. Sutherland,
- Jennifer M. Covello,
- Sarah E. Friend,
- Jordan D. Poley,
- Kim W. Koczka,
- Sara L. Purcell,
- Tara L. MacLeod,
- Bridget R. Donovan,
- Jorge Pino,
- Jose Luis González-Vecino,
- Javier Gonzalez,
- Jose Troncoso,
- Ben F. Koop,
- Simon L. Wadsworth, and
- Mark D. Fast
Salmon lice (Lepeophtheirus salmonis) are important ectoparasites of wild and farmed salmonids and cause major losses to the salmon farming industry throughout the Northern Hemisphere. With the emergence of resistance to several commonly used parasiticides, novel control strategies and integration of multiple treatment options are needed, including host immunostimulation. Here, we investigate the effects of a functional feed containing a peptidoglycan and nucleotide formulation on L. salmonis infection of Atlantic salmon (Salmo salar) by characterizing lice infection levels, the expression of several host immune genes, and the parasite transcriptomic response to the immunostimulated host. Although initial infection intensities were low, the low dose (LD) immunostimulant diet reduced the total lice burden by 50% relative to controls. Immunostimulant fed hosts up-regulated interleukin-1β in the skin and spleen. This gene has been implicated in successful responses of several salmonid species to salmon lice but is typically not observed in Atlantic salmon, suggesting a favorable influence on the immune response. Lice infecting LD immunostimulated salmon overexpressed genes putatively involved in parasite immunity, including carboxylesterases, and underexpressed genes putatively involved in feeding (e.g., proteases). These lice response genes further improve the characterization of the transcriptome of the non-model parasite by identifying genes potentially involved in evading host immunity. - OPEN ACCESS
- Tim J. Arciszewski,
- Kelly R. Munkittrick,
- Bruce W. Kilgour,
- Heather M. Keith,
- Janice E. Linehan, and
- Mark E. McMaster
Responses to chemical and physical stressors are commonly expected among organisms residing near the Athabasca oil sands. Physiological effects have been observed in fishes during field studies; but further effects associated with development are not clear or consistent among species. For instance, data from a fish fence in 2009 show declines in the relative abundances of some species, including Arctic grayling (Thymallus arcticus). In contrast, increases were seen in white sucker (Catostomus commersoni). This divergence suggests incomplete understanding of the status of fishes residing near the oil sands. However, an important challenge limiting understanding is the lack of reliable baseline or reference data. To overcome this challenge, we used iterative normal ranges and a historical data set (electrofishing surveys done from 1987 to 2014) to determine if changes have occurred in fishes captured in the lower Athabasca River. These analyses revealed clear increases in the lengths of white sucker and walleye (Sander vitreus) and their relative abundances during the spawning season. The occurrence of these changes may be associated with overwintering location, but reduced fishing pressure in Lake Athabasca, eutrophication, or a cumulative effect may explain the form of changes detected in this study. - OPEN ACCESSCities are under pressure to operate their services effectively and project costs of operations across various timeframes. In high-latitude and high-altitude urban centers, snow management is one of the larger unknowns and has both operational and budgetary limitations. Snowfall and snow depth observations within urban environments are important to plan snow clearing and prepare for the effects of spring runoff on cities’ drainage systems. In-house research functions are expensive, but one way to overcome that expense and still produce effective data is through citizen science. In this paper, we examine the potential to use citizen science for snowfall data collection in urban environments. A group of volunteers measured daily snowfall and snow depth at an urban site in Saskatoon (Canada) during two winters. Reliability was assessed with a statistical consistency analysis and a comparison with other data sets collected around Saskatoon. We found that citizen-science-derived data were more reliable and relevant for many urban management stakeholders. Feedback from the participants demonstrated reflexivity about social learning and a renewed sense of community built around generating reliable and useful data. We conclude that citizen science holds great potential to improve data provision for effective and sustainable city planning and greater social learning benefits overall.
- OPEN ACCESS
- Stephanie R. Januchowski-Hartley,
- Kimberly A. Selkoe,
- Natalya D. Gallo,
- Christopher E. Bird, and
- J. Derek Hogan
The Marianas Trench Marine National Monument (MNM) currently extends policy-based protection to deep-sea ecosystems contained within it, but managers require better understanding of the current knowledge and knowledge gaps about these ecosystems to guide decision-making. To address this need, we present a case study of the Marianas Trench MNM using in-depth interviews to determine scientists’ (1) current understanding of anthropogenic drivers of change and system vulnerability in deep-sea ecosystems; and (2) perceptions of the least understood deep-sea ecosystems and processes in the Marianas Trench MNM, and which of these, if any, should be research priorities to fill knowledge gaps about these systems and the impacts from anthropogenic drivers of change. Interview respondents shared similar views on the current knowledge of deep-sea ecosystems and potential anthropogenic drivers of change in the Marianas Trench MNM. Respondents also identified trench and deep pelagic (bathyal, abyssal, and hadal zones) ecosystems as the least understood, and highlighted climate change, litter and waste, mining and fishing, and interactions between these drivers of change as critical knowledge gaps. To fill key knowledge gaps and inform conservation decision-making, respondents identified the need for monitoring networks and time-series data. Our approach demonstrates how in-depth interviews can be used to elicit knowledge to inform decision-making in data-limited situations. - OPEN ACCESSWe describe the underwater light field of the Strait of Georgia in spring and summer, using apparent optical properties (reflectance, attenuation coefficient of downwelling irradiance, the average cosine of downwelling irradiance, and the attenuation of scalar irradiance). Both the attenuation and reflectance of photosynthetically available radiation (PAR; 400–700 nm) are highest in the turbid waters of the Fraser River plume, due to scattering by mainly inorganic particles and absorption by coloured dissolved organic matter, phytoplankton, and other organic particles. Light is most diffuse in the surface waters of the plume and least diffuse at depth and away from the plume. Throughout the Strait, blue and red wavelengths are attenuated most rapidly resulting in a green peak of reflectance, the portion of the electromagnetic spectrum that penetrates the most deeply. PAR is attenuated to 1% of its surface intensity within 6–22 m in the spring and 4–23 m in the summer. For red and blue light, the depth of 1% penetration is never deeper than 9 m. All of the visible radiation, with the exception of some green light, is absorbed within the outflowing layer (15–30 m) that is exported from the Strait with the estuarine circulation. The rapid extinction of light helps to explain the very shallow distribution of phytoplankton.
- OPEN ACCESSTotal Zn concentrations and Zn isotope ratios were measured, using multicollector inductively coupled plasma (ICP)-mass spectrometry (MS), in three species of aquatic insects collected from a stream in Peterborough, Ontario, Canada. Total Zn levels averaged 193 ± 88 μg/g dry weight (dw) in water striders (Heteroptera: Gerridae, Aquarius remigis) and were significantly higher than the concentrations measured in stonefly nymphs (Plecoptera: Perlidae, Acroneuria abnormis) and caddisfly larvae (Trichoptera: Limnephilidae, Pycnopsyche guttifer), i.e., 136 ± 34 μg/g dw and 125 ± 26 μg/g dw, respectively. Average delta values for 66Zn/64Zn in the water striders were approximately 0.7‰ lighter (−1.2‰ ± 1.0‰) and were significantly different than those measured for stoneflies (−0.45‰ ± 0.62‰) and caddisflies (−0.51‰ ± 0.54‰). Nitrogen isotope ratios were significantly different (P < 0.05) among the three species suggesting differences in trophic positioning. Similar to the Zn isotope ratios, δ 13C values for the water striders (−28.61‰ ± 0.98‰) were significantly different than those of the stoneflies and caddisflies, i.e., −30.75‰ ± 1.33‰ and −30.68‰ ± 1.01‰, respectively. The data suggest that the differences observed in Zn ratios relate to food source for these insects. Similar to their carbon sources, Zn in water striders appears to be primarily of terrestrial origin, and of aquatic origin for the other two species.
- OPEN ACCESSUnmanned aircraft systems (UASs) were tested for counting Chinook salmon (Oncorhynchus tshawytscha) redds as a more accurate, safer alternative to manned helicopter flights. Counting redds from the helicopter was less expensive and time consuming, but of the total redds counted at selected sites with a UAS, an average (± SD) of only 77% ± 14% was counted from the helicopter. A river-wide census of redds was not possible with a UAS because the study area was too large for the single field crew to survey. Simulation analyses were used to compare stratified random sampling (STRS) and sampling proportional to size (PPS) for estimating annual total redd counts from data collected with a UAS. The STRS estimates were more accurate and precise, whereas the PPS estimates, though biased, had 95% CIs that included the observed redd count more frequently. We strongly recommend that researchers conduct simulation analyses to evaluate alternative survey sampling methods if they are considering replacing census counts made from manned aircraft with counts estimated from data collected with a UAS. We conclude that UAS application reduces the risk inherent to manned aircraft flights, but the reduction in risk can come at the cost of estimates of population parameters that can sometimes be inaccurate and lack 95% CI coverage.
- OPEN ACCESSPersistence of absorbable sutures in fishes in waters below 10 °C affects surgical decisions including approach, closure strategy, and suture selection. We hypothesized that the rate of suture hydrolysis would vary directly with water temperature. Two absorbable monofilament 3-0 suture materials used in fish surgery, poliglecaprone (Monocryl™) and polyglyconate (Maxon™), were evaluated. The maximum tensile load (strength) was measured for suture loops (n = 6) maintained in filtered city water for 2, 4, 6, or 8 weeks at 4, 25, or 37 °C. For Maxon™ at 4 or 25 °C, tensile strength did not decrease over time. However, for Monocryl™ at 4 °C, 2-, 4-, and 8-week loops were stronger than baseline loops. At 25 °C, tensile strength of the suture material declined after 2 weeks. Also, at 37 °C, the optimal design temperature for both suture materials, the strength of Maxon™ decreased at 6 and 8 weeks. Two 4-week loops of Monocryl™ disintegrated when handled, and after 6 and 8 weeks, all were untestable. This study confirms that absorbable sutures lose strength more slowly at ambient temperatures lower than the optimal design temperature (e.g., human body temperature) and will likely be retained longer in fishes living in waters below 25 °C.