My research focuses on issues related to aquatic biodiversity, including: conservation of freshwater fishes (e.g. species at risk, invasive species), sustainable resource development and developing robust restoration and reclamation activities. My goals are to: build effective collaborations across Alberta and North America; to train the next generation of research leaders; to provide an atmosphere of respect and learning; to engage the public and stakeholders; and, to develop leading edge novel research to solve applied problems.
Research by Megan Edgar was recently highlighted in the media, including: CBC, Folio, Nature Alberta (link) and Chits and Chats podcast. Great job Megan!
Abstract:
The Chinese mystery snail Cipangopaludina fhinensis (Gray, 1834), a species native to Asia, is documented for the first time in Alberta, Canada, in McGregor Lake Reservoir in 2019. Here, we describe the initial finding of C. chinensis in Alberta, Canada, and biological information that may aid management efforts. Collected specimens were confirmed as C. chinensis through DNA barcoding. Analysis of growth rate, fecundity, and infection by digenean trematodes was assessed. It is unknown how C. chinensis arrived in Alberta. However, this species’ ability to withstand environmental stressors, such as desiccation, facilitates overland and long-distance transport via recreationists or deliberate release of C. chinensis into waterbodies. Snails collected from McGregor Lake Reservoir matched with GenBank results for C. chinensis from Korea. Analysis of digenean trematodes revealed that the population in McGregor Lake are not infected, as there were no cercariae present after 24 hours. Growth assessment over a period of 60 weeks revealed that shell length growth quickly outpaces growth in shell width. Upon emergence, C. chinensis are larger than many native snail species. The expansion of C. chinensis into Alberta poses potential negative consequences, such as decreased native snail biomass, increased nitrogen to phosphorus ratios, and additive impacts when paired with other invasive species.
Citation: Edgar M.*, Hanington P., Lu R., Proctor H., Zurawell R., Kimmel N. and M.S. Poesch (2022) The First Documented Occurrence and Life History Characteristics of the Chinese Mystery Snail (Cipangopaludina chinensis, Mollusca: Viviparidae) in Alberta, Canada. BioInvasions Records 11(2): 449-460.
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*Lab members: Megan Edgar and Mark Poesch. Check out opportunities in the lab!
University of Alberta academics are part of a project that received $24 million in federal funding to examine the link between the loss of biodiversity and the decline of Indigenous health. Dozens of academic and community-based researchers, both Indigenous and non-Indigenous, are joining forces for a six-year project to curb the decline of biodiversity and improve the well-being of Indigenous people throughout Canada and around the world.
The Ărramăt Project brings more than 150 Indigenous organizations and governments from around the world together to carry out 140 Indigenous-led, place-based research projects to examine the link between biodiversity and Indigenous health.
There are 12 academics from the University of Alberta involved in the project.
“The collapse of the cod stocks, massive forest fires in B.C., climate change, degradation of freshwater — there’s no end of examples where our non-Indigenous systems of resource management are flawed,” said Brenda Parlee, lead co-principal investigator and a non-Indigenous scholar and professor in the U of A’s faculty of agricultural, life and environment sciences in a news release.
Link to article (Folio)
Abstract:
Structural habitat enhancement has been long established as a popular tool to counter habitat loss due from land-use and development. One enhancement approach is the introduction of Coarse Woody Habitat (CWH) to improve the establishment of macrophyte, macroinvertebrate, and fish communities. Here we assess the benefit of CWH in Northern boreal lakes in the context of mitigation projects. We constructed Coarse Woody Habitat structures in a structure-less littoral zone of Lake Steepbank within the Oil Sands Region of Alberta, Canada. Enhancement structures featured increased macrophyte and invertebrate richness and biomass compared to reference sites and pre-treatment assessments over the course of three years. Enhanced sites also retained improved richness (macrophytes), diversity (macroinvertebrates) and biomass (both), despite STIN loss and degradation of enhancement structures over time. Using beta diversity components, constituting richness agreement, community differentiation and site relationships, and testing their relative importance revealed that replacement was more dominant for invertebrates and increasing similarity more important for macrophyte communities post-enhancement. Our study shows the value of CWH addition for macroinvertebrate and macrophyte communities in what is otherwise a structure-less environment. Community changes over time showcase how beta diversity should be more strongly incorporated in restoration and enhancement studies to quantify community shifts that otherwise would not be captured in alternative diversity measures.
Citation: Theis, S., Ruppert, J., Shirton, J. and M.S. Poesch (2022) Measuring beta diversity components and beneficial effects of coarse woody habitat introduction on invertebrate and macrophyte communities in a shallow northern boreal lake: implications for offsetting. Aquatic Ecology 56: 793-814.
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*Lab members: Sebastian Theis, Jonathan Ruppert, Jesse Shirton and Mark Poesch. Check out opportunities in the lab!
Great job Chloe!
Abstract:
Freshwater biodiversity is declining from impacts associated with anthropogenic stressors. Here, we use carbon (δ13C) and nitrogen (δ15N) stable isotopes to assess food web effects following a coal mine spill that displaced biota and altered biophysical stream characteristics. We compared isotopic niche metrics of benthic macroinvertebrates and the fish community, including non-native brook trout (Salvelinus fontinalis) and endangered Athabasca rainbow trout (Oncorhynchus mykiss), to infer spatial differences in site-specific resource use along a habitat disturbance gradient. Predatory benthic macroinvertebrate trophic position was elevated where impacts from the spill were most pronounced. Autochthonous carbon contribution to consumer diets was lowest in biota sampled at the most highly impacted site from the mine spill, leading to an unexpected expansion of the isotopic niche size of rainbow trout and the aquatic invertebrate community. Collectively, our results suggest spatial variation in trophic resource assimilation across multiple levels of the food web, fuelled by the allochthonous energy pathway in highly impacted study sites. We conclude this reflects a biotic response to altered basal aquatic resources following a major industrial disturbance.
Citation: Medinski, N.A., Maitland, B.M., Jardine, T.D., Drake, D.A.R. and M.S. Poesch (2022) A catastrophic coal mine spill in the Athabasca River watershed induces isotopic niche shifts in stream biota including an endangered rainbow trout ecotype. Canadian Journal for Fisheries and Aquatic Sciences 79(8): 1321-1334.
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*Lab members: Nathan Medinski, Bryan Maitland, Mark Poesch. Check out opportunities in the lab!
Abstract:
The field of stable isotope ecology is moving away from lethal sampling (internal organs and muscle) towards non-lethal sampling (fins, scales and epidermal mucus). Lethally and non-lethally sampled tissues often differ in their stable isotope ratios due to differences in metabolic turnover rate and isotopic routing. If not accounted for when using non-lethal tissues, these differences may result in inaccurate estimates of resource use and trophic position derived from stable isotopes. To address this, the authors tested whether tissue type, season and their interaction influence the carbon and nitrogen stable isotope ratios of fishes and whether estimates of species trophic position and resource use are affected by tissue type, season and their interaction. This study developed linear conversion relationships between two fin types and dorsal muscle, accounting for seasonal variation. The authors focused on three common temperate freshwater fishes: northern pike Esox lucius, yellow perch Perca flavescens and lake whitefish Coregonus clupeaformis. They found that fins were enriched in 13C and depleted in 15N compared to muscle in all three species, but the effect of season and the interaction between tissue type and season were species and isotope dependent. The estimates of littoral resource use based on fin isotope ratios were between 13% and 36% greater than those based on muscle across species. Season affected this difference for some species, suggesting the potential importance of using season-specific conversions when working with non-lethal tissues. Fin and muscle stable isotopes produced similar estimates of trophic position for northern pike and yellow perch, but fin-based estimates were 0.2–0.4 trophic positions higher than muscle-based estimates for lake whitefish. The effect of season was negligible for estimates of trophic position in all species. Strong correlations existed between fin and muscle δ13C and δ15N values for all three species; thus, linear conversion relationships were developed. The results of this study support the use of non-lethal sampling in stable isotope studies of fishes. The authors suggest that researchers use tissue conversion relationships and account for seasonal variation in these relationships when differences between non-lethal tissues and muscle,
and seasonal effects on those differences, are large relative to the scale of isotope values under investigation and/or the trophic discrimination factors under use.
Citation: Roberts, K.N., Lund, T., Hayden, B. and M.S. Poesch (2022) Season and species influence stable isotope ratios between lethally and non-lethally sampled tissues in freshwater fish. Journal of Fish Biology 100 (1): 229-241. DOI: 10.1111/jfb.14939
Finalist for FSBI Huntingford Medal. Note: One of two papers that received the “Highly Commended” designation.
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*Lab members: Karling Roberts, Mark Poesch. Check out opportunities in the lab!
Abstract:
The use of stable isotopes to study trophic interactions and food webs has become a common practice in ecology. Until recently, parasites were largely omitted from these analyses despite their known contribution to ecosystem complexity and function. Long-standing assumptions about the enrichment of δ15N in consumers relative to their resources occasionally placed parasites in trophic positions above their hosts. However, recent literature has shown that unlike consumers to prey, parasites do not reliably exhibit enrichment in δ15N. This is particularly true of helminth endoparasites in the class cestoda, which tend to be depleted in δ15N. We developed empirical estimates of nitrogen and carbon stable isotope ratios from a cestode parasite (Ligula intestinalis) across four fish hosts from two lakes in northern Alberta, Canada. We found that L. intestinalis were depleted in δ15N relative to their hosts across all host fish species, with mean nitrogen discrimination factors (Δ15N) ranging from -1.92 ± 0.24 ‰ to -2.91 ± 1.17 ‰. In contrast, δ 13C values did not differ significantly in any direction between hosts and their parasites. Mean carbon discrimination factors (Δ13C) ranged from -0.66 ± 2.69 ‰ to 0.04 ± 1.53 ‰. We also tested for relationships between proportional parasite biomass and discrimination factor (Δ15N & Δ13C), and found high variability in strength and direction of these correlations across species. The direction and magnitude of nitrogen discrimination we found for L. intestinalis is similar to that of previous cestode stable isotope studies and may indicate consistency across the class cestoda. However, class cestoda is incredibly diverse and relatively few studies have examined host-parasite
discrimination factors within the clade. We encourage additional research into host-parasite discrimination factors for the class cestoda, and across all parasite taxa. This could facilitate the inclusion of these widespread interactions into food web studies, thus improving our knowledge of trophic structure and dynamics.
Citation: Finn, K., Roberts, K.N. and M.S. Poesch (2022) Cestode parasites are depleted in 15N relative to their fish hosts in northern Alberta, Canada. Fisheries Research 248: 106193.
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*Lab members: Karling Roberts, Mark Poesch. Check out opportunities in the lab!
Abstract:
Trophic levels can be applied to describe the ecological role of organisms in food webs and assess changes in ecosystems. Stable isotopes analysis can assist in the understanding of trophic interactions and use of food resources by aquatic organisms. The local ecological knowledge (LEK) of fishers can be an alternative to advance understanding about fish trophic interactions and to construct aquatic food webs, especially in regions lacking research capacity. The objectives of this study are: to calculate the trophic levels of six fish species important to fishing by combining data from stable isotopes analysis and fishers’ LEK in two clear water rivers (Tapajós and Tocantins) in the Brazilian Amazon; to compare the trophic levels of these fish between the two methods (stable isotopes analysis and LEK) and the two rivers; and to develop diagrams representing the trophic webs of the main fish prey and predators based on fisher’s LEK. The fish species studied were Pescada (Plagioscion squamosissimus), Tucunaré (Cichla pinima), Piranha (Serrasalmus rhombeus), Aracu (Leporinus fasciatus), Charuto (Hemiodus unimaculatus) and Jaraqui (Semaprochilodus spp.). A total of 98 interviews and 63 samples for stable isotopes analysis were carried out in both rivers. The average fish trophic levels did not differ between the stable isotopes analysis and the LEK in the Tapajós, nor in the Tocantins Rivers. The overall trophic level of the studied fish species obtained through the LEK did not differ from data obtained through the stable isotopes analysis in both rivers, except for the Aracu in the Tapajós River. The main food items consumed by the fish according to fishers’ LEK did agree with fish diets as described in the biological literature. Fishers provided useful information on fish predators and feeding habits of endangered species, such as river dolphin and river otter. Collaboration with fishers through LEK studies can be a viable approach to produce reliable data on fish trophic ecology to improve fisheries management and species conservation in tropical freshwater environments and other regions with data limitations.
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*Lab members: Mark Poesch. Check out opportunities in the lab!
Abstract:
Effective conservation requires that species recovery measures are informed by rigorous scientific research. For imperilled freshwater fishes and mussels in Canada, numerous research gaps exist, in part owing to the need for specialized research methods. The Canadian Freshwater Species at Risk Research Network (SARNET) was formed, and identified or implemented approaches to address current research gaps, including: 1) captive experimental research populations; 2) non-lethal methods for estimating abundance and distribution; 3) non-lethal field methods to measure life-history parameters; 4) species distribution models informed by co-occurring species; 5) integration of conservation physiology into habitat and threat science; 6) evidence syntheses to evaluate threats and recovery strategies; 7) disease-transmission models to understand mussel-host relationships; 8) experimental mesocosms and manipulative experiments to evaluate key habitat stressors; 9) threat and hazard models for predictive applications; and, 10) rigorous evaluation of surrogate species. Over a dozen threat and recovery-focused SARNET-research applications are summarized, demonstrating the value of a coordinated research program between academics and government to advance scientific research on, and to support the recovery of, imperilled freshwater species.
Citation: Castaneda, R.A., Ackerman, J.D., Chapman, L.J., Cooke, S.J., Cuddington, K., Dextrase, A., Jackson, D.A., Koops, M.A., Krkosek, M., Loftus, K., Mandrak, N.E., Martel, A.L., Molnar, P., Morris, T.J., Pitcher, T.E., Poesch, M.S., Power, M., Pratt, T.C., Reid, S.M., Rodriguez, M.A., Rosenfeld, J., Wilson, C., Zanatta, D.T. and D.A.R. Drake. (2021) Approaches and research needs for advancing the protection and recovery of imperilled freshwater fishes and mussels in Canada. Canadian Journal of Fisheries and Aquatic Sciences 78 (9): 1356-1370.
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*Lab members: Mark Poesch. Check out opportunities in the lab!
