Clayton H. Riddell Faculty of Environment, Earth, and Resources Scholarly Works
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- ItemOpen AccessPredation of archival tagged Dolly Varden, Salvelinus malma, reveals predator avoidance behaviour and tracks feeding events by presumed beluga whale, Delphinapterus leucas, in the Beaufort Sea(2021-12-20) Gallagher, Colin P.; Storrie, Luke; Courtney, Michael B.; Howland, Kimberly L.; Lea, Ellen V.; MacPhee, Shannon; Loseto, LisaAbstract Background We report compelling evidence suggesting a predation event of a pop-up satellite archival tagged anadromous Dolly Varden (Salvelinus malma) by a marine mammal during summer in the Beaufort Sea based on abrupt changes in temperature and vertical movements. This observation provides insight on predator avoidance behaviour by Dolly Varden and the predator’s feeding frequency while the tag was ingested. Based on published distribution and ecology information, we presumed the predator was a beluga whale (Delphinapterus leucas). Supplemental satellite telemetry data from previously tagged Dolly Varden and beluga whales were used to determine the extent of spatial and vertical overlap between species in the area where predation occurred. Results Prior to the predation event, depths and temperatures occupied by the tagged Dolly Varden averaged 1.1 m and 3.1 °C, respectively. On July 7, 2020, depths remained shallow apart from a sudden dive to 12.5 m (16:45 UTC) followed by a precipitous increase in temperature from 4.4 to 27.1 °C (16:52 UTC) suggesting predation by an endotherm. Subsequent readings indicated the endotherm had a resting stomach temperature of 36.1 °C. Including the predation event, eight separate feeding events were inferred during the 20-h period the tag was ingested (before presumed regurgitation) based on subsequent declines in stomach temperatures (mean decline to 31.1 °C) that took an average of 24.1 min to return to resting temperature. The predator occupied mainly shallow depths (mean = 2.3 m), overlapping with tagged belugas that spent 76.9% of their time occupying waters ≤ 2.5 m when frequenting the area occupied by tagged Dolly Varden in the Canadian Beaufort Sea in July. Back-calculation based on tag drift and mean displacement by tagged belugas indicated the predation likely occurred west of the Mackenzie Delta. Conclusion Our findings provide new information on both anti-predator behaviour by, and marine predators of, Dolly Varden in the Beaufort Sea. We provide the first estimate of feeding frequency and stomach temperature recovery in a presumed wild beluga, and evidence for shallow foraging behaviour by belugas. Elucidating the likely predator and exploring the extent of overlap between Dolly Varden and beluga whales contributes towards knowledge on the trophic interactions in the Beaufort Sea.
- ItemOpen AccessDistinct Ocean Responses to Greenland's Liquid Runoff and Iceberg Melt(American Geophysical Union, 2021-11-11) Marson, Juliana M.; Gillard, Laura C.; Myers, Paul G.While Greenland discharge has been increasing in the last decades, its impact on the Meridional Overturning Circulation (MOC) is not clearly established. Because of that, the accuracy of this discharge representation in ocean models has not been a priority in large-scale circulation studies. Many models prescribe Greenland discharge solely as liquid runoff from the coast—even though around half of this mass loss is attributed to solid discharge. In this study, we use sensitivity experiments carried out with the Nucleus for European Modeling of the Ocean general circulation model to show the most relevant impacts that different Greenland solid discharge parameterizations (transforming it to liquid runoff or explicitly representing it through an iceberg model) have on the western subpolar Atlantic. We find that icebergs act as freshwater reservoirs that affect how much, when, and where freshwater is delivered to the ocean. They carry large amounts of freshwater away from boundary currents, releasing it in the interior of the subpolar gyre. Moreover, the amount and variability of freshwater delivered to the ocean depend not only on the characteristics of Greenland discharge itself but also on the environmental conditions icebergs are subjected to. We also find a large difference in subsurface temperatures in the Gulf of Saint Lawrence, which suggests that different Greenland discharge parameterizations might have far reaching implications beyond the MOC. Although differences in ocean fields between the simulations are usually small and within their interannual variability, they might be relevant as Greenland calving rates increase with global warming.
- ItemOpen AccessA meta-collection of nitrogen stable isotope data measured in Arctic marine organisms from the Canadian Beaufort Sea, 1983–2013(2021-09-06) Ehrman, Ashley; Hoover, Carie; Giraldo, Carolina; MacPhee, Shannon A.; Brewster, Jasmine; Michel, Christine; Reist, James D.; Power, Michael; Swanson, Heidi; Niemi, Andrea; Walkusz, Wojciech; Loseto, LisaAbstract Objectives Existing information on Arctic marine food web structure is fragmented. Integrating data across research programs is an important strategy for building a baseline understanding of food web structure and function in many Arctic regions. Naturally-occurring stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) measured directly in the tissues of organisms are a commonly-employed method for estimating food web structure. The objective of the current dataset was to synthesize disparate δ15N, and secondarily δ13C, data in the Canadian Beaufort continental shelf region relevant to trophic and ecological studies at the local and pan-Arctic scales. Data description The dataset presented here contains nitrogen and carbon stable isotope ratios (δ15N, δ13C) measured in marine organisms from the Canadian Beaufort continental shelf region between 1983 and 2013, gathered from 27 published and unpublished sources with associated sampling metadata. A total of 1077 entries were collected, summarizing 8859 individual organisms/samples representing 333 taxa across the Arctic food web, from top marine mammal predators to primary producers.
- ItemOpen AccessThe effect of crop species on DNase-producing bacteria in two soils(2021-03-12) Kamino, Leila N; Gulden, Robert HAbstract Purpose Extracellular deoxyribonucleases (exDNases) from microbial origin contribute substantially to the restriction of extracellular DNA (exDNA) in the soil. Hence, it is imperative to understand the diversity of bacterial species capable of performing this important soil function and how crop species influence their dynamics in the soil. The present study investigates the occurrence of DNase-producing bacteria (DPB) in leachate samples obtained from soils in which the crop species of alfalfa (Medicago sativa L.), canola (Brassica napus L.), soybean (Glycine max [L.] Merr.) and wheat (Triticum aestivum L.) were raised in a growth room. Methods Selective media containing methyl green indicator was used to screen for DPB from leachate samples, whereas the 16S rRNA sequence analysis was employed to identify the isolates. Results The proportion of culturable DPB ranged between 5.72 and 40.01%; however, we did observe specific crop effects that shifted throughout the growing period. In general, higher proportions of exDNase producers were observed when the soils had lower nutrient levels. On using the 16S rRNA to classify the DPB isolates, most isolates were found to be members of the Bacillus genera, while other groups included Chryseobacterium, Fictibacillus, Flavobacterium, Microbacterium, Nubsella, Pseudomonas, Psychrobacillus, Rheinheimera, Serratia and Stenotrophomonas. Five candidate exDNase/nuclease-encoding proteins were also identified from Bacillus mycoides genomes using online databases. Conclusion Results from this study showed that crop species, growth stage and soil properties were important factors shaping the populations of DPB in leachate samples; however, soil properties seemed to have a greater influence on the trends observed on these bacterial populations. It may be possible to target soil indigenous bacteria that produce exDNases through management to decrease potential unintended effects of transgenes originating from genetically modified organisms (GMOs) or other introduced nucleic acid sequences in the environment.
- ItemOpen AccessThe EU Horizon 2020 project GRACE: integrated oil spill response actions and environmental effects(2019-07-16) Jørgensen, Kirsten S; Kreutzer, Anne; Lehtonen, Kari K; Kankaanpää, Harri; Rytkönen, Jorma; Wegeberg, Susse; Gustavson, Kim; Fritt-Rasmussen, Janne; Truu, Jaak; Kõuts, Tarmo; Lilover, Madis-Jaak; Seiler, Thomas-Benjamin; Hollert, Henner; Johann, Sarah; Marigómez, Ionan; Soto, Manu; Lekube, Xabier; Jenssen, Bjørn M; Ciesielski, Tomasz M; Wilms, Lonnie B; Högström, Rune; Pirneskoski, Mika; Virtanen, Seppo; Forsman, Björn; Petrich, Chris; Phuong-Dang, Nga; Wang, FeiyueAbstract This article introduces the EU Horizon 2020 research project GRACE (Integrated oil spill response actions and environmental effects), which focuses on a holistic approach towards investigating and understanding the hazardous impact of oil spills and the environmental impacts and benefits of a suite of marine oil spill response technologies in the cold climate and ice-infested areas of the North Atlantic and the Baltic Sea. The response methods considered include mechanical collection in water and below ice, in situ burning, use of chemical dispersants, natural biodegradation, and combinations of these. The impacts of naturally and chemically dispersed oil, residues resulting from in situ burning, and non-collected oil on fish, invertebrates (e.g. mussels, crustaceans) and macro-algae are assessed by using highly sensitive biomarker methods, and specific methods for the rapid detection of the effects of oil pollution on biota are developed. By observing, monitoring and predicting oil movements in the sea through the use of novel online sensors on vessels, fixed platforms including gliders and the so-called SmartBuoys together with real-time data transfer into operational systems that help to improve the information on the location of the oil spill, situational awareness of oil spill response can be improved. Methods and findings of the project are integrated into a strategic net environmental benefit analysis tool (environment and oil spill response, EOS) for oil spill response strategy decision making in cold climates and ice-infested areas.