Mark S. Poesch

Climate Change Impacts on Freshwater Fishes: A Canadian Perspective

Current and projected patterns of global climate change are a major concern to freshwater fisheries in Canada. The magnitude of the impacts of climate change vary among species and ecoregions. The latest climate change scenario projections for Canada suggest that by 2050 temperatures will increase between about 4.9°C ± 1.7°C (average mean ± standard deviation) and 6.6°C ± 2.3°C under the Representative Concentration Pathways (RCPs) 2.6 and 8.5 emission scenarios, respectively. These changes will have an important influence on the physiology, distribution, and survival of freshwater fishes, as well as other ecological processes in direct, indirect, and complex ways. Here we provide a perspective from the Canadian Aquatic Resources Section on the impacts of climate change to freshwater fishes. Given the geographic size and diversity of landscapes within Canada, we have divided our perspective into three regions: eastern, western, and northern Canada. We outline the impacts of climate change to these regions and outline challenges for fisheries managers. Because climate change does not operate in isolation of other environmental threats, nor does it impact species in isolation, we suggest improved interjurisdictional integration and the use of an adaptive and ecosystem-based approach to management of these threats.

Characterization of Naphthenic Acids and Other Dissolved Organics in Natural Water from the Athabasca Oil Sands Region, Canada

With growth of the Canadian oil sands industry, concerns have been raised about possible seepage of toxic oil sands process-affected water (OSPW) into the Athabasca River (AR). A sampling campaign in fall 2015 was undertaken to monitor for anthropogenic seepage while also considering natural sources. Naphthenic acids (NAs) and thousands of bitumen-derived organics were characterized in surface water, groundwater, and OSPW using a highly sensitive online solid phase extraction-HPLC-Orbitrap method. Elevated NA concentrations and bitumen-derived organics were detected in McLean Creek (30.1 μg/L) and Beaver Creek (190 μg/L), two tributaries that are physically impacted by tailings structures. This was suggestive of OSPW seepage, but conclusive differentiation of anthropogenic and natural sources remained difficult. High NA concentrations and bitumen-derived organics were also observed in natural water located far north of the industry, including exceedingly high concentrations in AR groundwater (A5w-GW, 2000 μg/L) and elevated concentration in a tributary river (Pierre River, 34.7 μg/L). Despite these evidence for both natural and anthropogenic seepage, no evidence of any bitumen-derived organics was detected at any location in AR mainstem surface water. The chemical significance of any bitumen-derived seepage to the AR was therefore minimal, and focused monitoring in tributaries will be valuable in the future.

Developing Standardized Methods for Sampling Freshwater Fishes with Multiple Gears: Effects of Sampling Order versus Sampling Method

AbstractDeveloping robust methodologies for sampling freshwater fishes is important for the assessment and recovery of aquatic biodiversity. Commonly, sampling protocols recommend the use of both electrofishing and seining to reduce bias when sampling freshwater fishes. The objective of this study was to determine whether sampling method, sampling order, or the combination of these influenced the assessment of diversity and abundance of common or rare freshwater fishes at both the species and assemblage level. Fifty sites were sampled in the Sydenham River, Ontario, Canada, where paired sites were sampled using both electrofishing and seine netting in close proximity but also reversing the initial sampling order. Differences in the abundance and richness of common and rare freshwater fishes were tested with two-way ANOVA and multivariate ANOVA. Multivariate differences in the representation of species assemblages were compared using Procrustes analysis across ordinations built using differences in samplin...

Comparative swimming and station-holding ability of the threatened Rocky Mountain Sculpin (Cottus sp.) from four hydrologically distinct rivers

Abstract Hydrologic alterations, such as dams, culverts or diversions, can introduce new selection pressures on freshwater fishes, where they are required to adapt to novel environmental conditions. Our study investigated how species adapt to natural and altered stream flow, where we use the threatened Rocky Mountain Sculpin (Cottus sp.) as a model organism. We compared the swimming and station-holding performance of Rocky Mountain Sculpin from four different hydrologic regimes in Alberta and British Columbia, including the North Milk River, a system that experiences increased flows from a large-scale diversion. We measured the slip (Uslip) and failure (Uburst) velocities over three constant acceleration test trials. Uslip was defined as the point at which individuals required the addition of bursting or swimming to maintain position. Uburst was defined as the point at which individuals were unable to hold position in the swimming chamber through swimming, bursting or holding techniques without fully or partially resting on the electrified back plate. We found individuals from the Flathead River in British Columbia (with the highest natural flow) failed at significantly higher Uburst velocities than fish from the southern Albertan populations. However, there was no relationship between peak hydrologic flow from the natal river and Uburst or Uslip. Further, Uburst velocities decreased from 51.8 cm s−1 (7.2 BL s−1) to 45.6 cm s−1 (6.3 BL s−1) by the third consecutive test suggesting the use of anaerobic metabolism. Uslip was not different between trials suggesting the use of aerobic metabolism in station-holding behaviours (Uslip). Moreover, we found no significant differences in individuals from the altered North Milk River system. Finally, individual caudal morphological characteristics were related to both slip and failure velocities. Our study contributes to the conservation of Rocky Mountain Sculpin by providing the first documentation of swimming and station-holding abilities of this benthic fish.

Bioaccumulation of Tl in otoliths of Trout-perch (Percopsis omiscomaycus) from the Athabasca River, upstream and downstream of bitumen mining and upgrading

It has been suggested that open pit mining and upgrading of bitumen in northern Alberta releases Tl and other potentially toxic elements to the Athabasca River and its watershed. We examined Tl and other trace elements in otoliths of Trout-perch (Percopsis omiscomaycus), a non-migratory fish species, collected along the Athabasca River. Otoliths were analyzed using ICP-QMS, following acid digestion, in the metal-free, ultraclean SWAMP laboratory. Compared to their average abundance in the dissolved (<0.45 μm) fraction of Athabasca River, Tl showed the greatest enrichment in otoliths of any of the trace elements, with enrichments decreasing in the order Tl, Sr, Mn, Zn, Ba, Th, Ni, Rb, Fe, Al, Cr, Ni, Cu, Pb, Co, Li, Y, V, and Mo. Normalizing Tl in the otoliths to the concentrations of lithophile elements such as Li, Rb, Al or Y in the same tissue reveals average enrichments of 177, 22, 19 and 190 times, respectively, relative to the corresponding ratios in the water. None of the element concentrations (Tl, Li, Rb, Al, Y) or ratios were significantly greater downstream of industry compared to upstream. This natural bioaccumulation of Tl most likely reflects the similarity in geochemical and biological properties of Tl+ and K+. SUMMARY OF MAIN FINDINGS: Thallium is enriched in fish otoliths, relative to the chemical composition of the river, to the same degree both upstream and downstream of industry.

Selenium in surface waters of the lower Athabasca River watershed: Chemical speciation and implications for aquatic life

Selenium in the lower Athabasca River (Alberta, Canada) is of concern due to potential inputs from the weathering of shallow bitumen deposits and emissions from nearby surface mines and upgraders. Understanding the source of this Se, however, is complicated by contributions from naturally saline groundwater and organic matter-rich tributaries. As part of a two-year multi-disciplinary study to assess natural and anthropogenic inputs, Se and its chemical speciation were determined in water samples collected along a ∼125 km transect of the Athabasca River and associated tributaries. Selenium was also determined in the muscle of Trout-perch (Percopsis omiscomaycus), a non-migratory fish species, that were sampled from selected locations. Dissolved (<0.45 μm) Se in the Athabasca River was consistently low in 2014 (0.11 ± 0.02 μg L-1; n = 14) and 2015 (0.16 ± 0.02 μg L-1; n = 21), with no observable increase from upstream to downstream. Selenate was the predominant inorganic form (∼60 ng L-1) and selenite was below detection limits at most locations. The average concentration of Se in Trout-perch muscle was 2.2 ± 0.4 mg kg-1 (n = 34), and no significant difference (p > 0.05) was observed between upstream and midstream (industrial) or downstream reaches. Tributary waters contained very low concentrations of Se (typically < 0.1 μg L-1), which was most likely present in the form of dissolved organic colloids.

Native freshwater species get out of the way: Prussian carp ( Carassius gibelio ) impacts both fish and benthic invertebrate communities in North America

Prussian carp (Carassius gibelio) are one of the most noxious non-native species in Eurasia. Recently, Prussian carp, a non-native freshwater fish species, were genetically confirmed in Alberta, Canada and have been rapidly expanding their range in North America since establishment. Given their rapid range expansion, there is an increasing need to determine how Prussian carp may impact native species. We assessed the severity of the Prussian carp invasion by (i) determining their impact on fish communities, (ii) assessing their impact on benthic invertebrate communities, (iii) evaluating if Prussian carp alter abiotic conditions, and (iv) identifying where we find higher abundances of Prussian carp. When Prussian carp were established, we found significant changes to the fish community. Correspondingly, the degree of impact to benthic invertebrate communities was related to the stage of invasion (none, early or recent), where changes in fish communities were significantly concordant with changes in benthic invertebrate communities. Finally, we found that higher abundances of Prussian carp were significantly associated with lower abundances of a majority of native fish species. Altogether, using three lines of evidence, we determine that Prussian carp can have wide-ranging impacts on freshwater ecosystems in North America, pressing the need for management intervention.

Finding the Path to a Successful Graduate and Research Career: Advice for Early Career Researchers

The path to a successful graduate and research career is a complex and difficult one. Early career researchers (ECRs) have myriad choices and tasks to prioritize and complete as they build their CV but are often confronted with unfamiliar situations in which advice from more senior researchers can be extremely valuable. Here, we summarize a recent workshop held for ECRs by the Canadian Aquatic Resource Section of the American Fisheries Society (AFS) with support from the Education Section. Sessions touched on (1) getting published, (2) science communication and outreach, (3) scoring a job or grad school position, and (4) working within the science–policy interface. The decades of collective experience brought to the table should be shared with the broader readership of AFS because it may prove useful to ECRs as well as stimulate meaningful conversations on these important and timely issues.