Yael Lewis, MSc Candidate, Orihel Lab The effects of microplastics on zooplankton and emerging insect communities in a littoral limnocorral experiment Although microplastics research has rapidly accelerated in the last few years, our understanding of their effects on freshwater invertebrates, particularly under environmentally relevant conditions, remains limited. Using in-situ limnocorrals at the International Institute for Sustainable Development – Experimental Lakes Area (IISD-ELA), we investigated the effects of a microplastic mixture on zooplankton and emerging insect communities. We installed 12 open-bottom limnocorrals in the littoral zone of a boreal lake in June of 2022 and added an environmentally relevant range of microplastic concentrations in a regression-based design. Our microplastic mixture consisted of distinctively coloured polystyrene, polyethylene, and polyethylene terephthalate fragments in equal parts by count, manufactured with common plastic additives. I sampled the zooplankton and emerging insect communities pre-addition and every week thereafter for the 8-week duration of the experiment. To evaluate possible longer-term effects, I sampled the emerging insect community again in May of 2023 over the partially enclosed bases of the limnocorrals. I assessed the relationship between nominal microplastic concentration and the abundance and community composition of zooplankton and insects. Microplastic concentration was negatively related to total zooplankton abundance at weeks 1 and 5 post-addition and drove changes in community composition at week one. Evidence for microplastic effects on the emerging insect community was more limited – microplastic concentration was negatively related to insect emergence only at week 2, and the total seasonal emergence exhibited only a weak relationship with microplastic concentration. There were no effects of microplastic on insect community composition. I anticipate my results will inform policy regarding ecological risk thresholds for microplastics in freshwater ecosystems.
Dr. Ian Richter, Postdoctoral Fellow, Blanchfield Lab, Queen's University Using the metabolic theory of ecology and size spectrum modelling to develop predictive stream fish productivity models Secondary production is indicative of the amount of energy available to higher trophic levels and can provide valuable insight into the dynamics of energy transfer within an ecosystem. Fish production incorporates a wide range of key response metrics such as abundance, biomass, growth, and reproduction, into one quantitative metric but requires resource-intensive data for empirical estimation. An alternative approach to evaluating the distribution and transfer of energy within aquatic ecosystems is size spectrum modelling which is reflects the negative scaling relationship between abundance and body size. While many studies have investigated fish productivity, few have evaluated different methods of estimating production or investigated the key drivers of productivity in riverine ecosystems. In this presentation, I present my research that focuses on investigating different approaches to predict the biomass production of stream fish assemblages using the metabolic theory of ecology and size spectrum modeling. More specifically, I test whether the metabolic theory of ecology and published standard production models can provide precise estimates of total stream fish productivity, investigate how a combination of abiotic and biotic variables are related to stream fish productivity in wadeable Ontario streams, and evaluate the effects of stream classification, spatial scale, and sampling design on the key parameters of riverine size spectrum models. Overall, this research demonstrates that published standard fish production models can be used to estimate productivity, that productivity is better predicted by biotic than abiotic variables, and that size spectra models at broad spatial scales can be used to investigate the movement of energy at higher trophic levels in river ecosystems. My research furthers our knowledge on the biomass production of stream fish communities and can serve a wide range of applications, including conservation and management efforts surrounding stream fish communities.
The Departmental I-EDIAA committee will be screening the 30-minute film ‘Signal Fire’. This film progressed out of the working group composed of Canadian scientists and Indigenous elders and scholars that published “Towards Reconciliation: 10 Calls to Action to Natural Scientists Working in Canada” in Facets (Wong et al., 2020).
More information about the film, and its trailer, can be found at: https://www.signalfirefilm.ca/watch Following the screening, everyone is welcome to participate in a discussion (~20 minutes). Those interested will break into small groups (using several rooms on the 3rd floor) and will be provided a few questions to guide reflection and discussion. We look forward to seeing everyone at this screening and discussion. Dr. Ian Strachan, Professor, Department of Geography and Planning, Queen's University Understanding Carbon Cycling in Peatland Systems from Disturbance Through Restoration The operations of the Canadian Horticultural Peat Industry result in a disturbance to the natural carbon (C) functioning of selected peatlands. While the disturbed area is small in comparison to the total peatland area, nonetheless, during the years of active harvesting, these former peatlands are net C sources to the atmosphere. Following the cessation of harvesting operations, for any period left unrestored, the peatlands remain large sources of C to the atmosphere. Post-disturbance, the goal of active restoration is to return C functioning of the disturbed ecosystem to one resembling the pre-disturbance state. If the rewetting and revegetation process is successful in re-establishing conditions like that of an undrained peatland, this means a return to a sink for CO2 and a source of methane but an overall annual sink for carbon.
In this presentation, I provide examples of our Industry-partnered NSERC research where we have for the first time quantified the emissions from partially drained peatlands undergoing active production and have shown that restoration successfully returns the C sink function of peatlands. In the first example, several years of study in an eastern peatland indicated a decay in C emissions through years since harvesting began. We found that this resulted from the increasingly recalcitrant (older) C being exposed as years of harvest continued; a finding that was corroborated by C dating of the peat and measurements of humification. In the second example, the net ecosystem exchange (NEE) of C was continuously measured for multiple years in restored peatlands in eastern and western Canada using the eddy covariance method. We identified small but significant differences in respiration driven by temperature that were responsible for differences in cumulative NEE between years. In both locations, having the soil moisture consistently near the surface was linked to success. After ~15 years post-restoration, the eastern peatland had a mean net ecosystem uptake of 78 ± 17 g C m−2 year−1 which was similar to a reference undisturbed peatland. The more-newly restored western peatland showed greater spatial variation in NEE resulting from differences in soil moisture conditions across the site with wetter locations more closely resembled the NEE of an undisturbed peatland. Combined, all site years allow us to see the resulting restoration trajectory in terms of C function. Finally, through a radiative forcing model, we showed that restoration immediately following the cessation of harvesting operations would result in the restored ecosystem achieving a future net C sink status 7-8 times sooner than would a 20-year delay in restoration. Our results are currently being used to update emissions factors for Canada’s national C inventory. Zoe Kane, PhD Candidate, Smol Lab Using changes in Cladocera assemblages to determine how ornithogenic inputs structure freshwater ecosystems Seabirds can be considered biovectors, transporting large concentrations of nutrients (e.g., nitrogen (N), phosphorous (P)) and metals (e.g., Cd, Zn, Hg) from their marine feeding grounds to their terrestrial breeding grounds. Seabird fertilizes their nesting sites by depositing feces, feathers, carcasses, and eggshells, which can be tracked directly (e.g., sterol/stanol to characterize guano deposits) or from their influence on nearby waterbodies (e.g., nutrient enrichment and/or pH changes traced using subfossil algal assemblages over time). Recent paleolimnological studies from PEARL reconstructed and hindcasted the population dynamics of Baccalieu Islands vulnerable Leach's Storm petrel population (Hydrobates leucorhous, hereafter LESP) to assess the effects of natural and anthropogenic stressors.
Adding to the several paleolimnological proxies used to track and reconstruct historical LESP inputs on ponds on Baccalieu island (Lunin, Brister, Gull and Mainland Reference ponds), I have implemented Cladocerans, or water fleas, which are well-known paleolimnological indicators (but as yet unexplored in these novel ornithological-limnological studies) as their species-specific exoskeletal remains are well preserved in sediment. They have a pivotal role in aquatic food webs, occupying an intermediate trophic position between top-down regulators and bottom-up factors, providing a critical link between the eutrophication process and the implications of elevated nutrient conditions on higher trophic levels. My results build on previous work that examined how seabird-derived nutrients influence primary production and algal assemblages in highly impacted ponds. I demonstrate that shifts from littoral/benthic to pelagic cladoceran taxa coincide with peaks in the inferred LESP population, highlighting the importance of seabird inputs to limnological conditions and eutrophication in several ponds on Baccalieu Island. Dr. Dilini Abeyrama, Post-doctoral Fellow, Lougheed Lab, Queen's University Population differentiation of Southern Ocean seabirds The Southern Ocean is a remote but unique ecosystem with high winds, strong currents, and a handful of islands surrounding the Antarctic continent. Reduced gene flow due to these physical and non-physical barriers supports rapid evolution and endemism within the Southern Ocean. Seabirds are a good model to study barrier-mediated speciation as they face a limited number of physical barriers, yet they are a highly diversified group. In my thesis, I used molecular markers to study population differentiation in five Southern Ocean seabird species at the three levels: among ocean basins, within oceans and within a single island. Sooty albatross (Phoebetria fusca) and yellow-nosed albatross showed population differentiation between Atlantic and Indian Ocean basins. Two sister species of yellow-nosed albatross, Atlantic (Thalassarche chlororhynchos) and Indian (Thalassarche carteri), both showed population genetic structure within Atlantic and Indian Oceans, respectively. The other two study species, Kerguelen shags (Phalacrocorax verrucosus) and gentoo penguins (Pygoscelis papua) breeding on Kerguelen Island, showed genetic structure among different breeding colonies of each species on the same island. Non-physical barriers such as natal philopatry and at-sea distribution, are limiting gene flow in the Southern Ocean at different geographic scales.
Dr. Amanda Grusz, Assistant Professor, University of Minnesota Duluth Evaluating a drought-driven model for the evolution of obligate asexual reproduction Obligate apomixis -- asexual reproduction by seed, spore, or egg -- has evolved repeatedly across the tree of life, in diverse organisms ranging from animals (such as reptiles, insects, and fishes) to angiosperms and other plants. Despite its many origins, and the intriguing ecological and evolutionary parallels among them, little is known regarding the causes and long-term consequences of this heritable reproductive syndrome. Some studies suggest that drought, or periodic water limitation, could be key to driving the repeated evolution of obligate apomixis. To evaluate the drought hypothesis, my lab is uniting genomic, spatial, environmental, and life history data (across multiple evolutionary and ecological scales), leveraging ferns as a model system. Current estimates indicate that 10–30% of ferns exhibit obligate apomixis, which has evolved repeatedly in xeric and monsoonal environments around the world. Dry environments impose major constraints on plant life histories and the fern life cycle is especially vulnerable. This study is focused primarily on North American desert ferns and integrates reproductive traits (karyotype, gametophyte development, and spore size/number), climate and microhabitat, and phylogenomic data to specifically ask: Does environmental niche predict obligate apomixis or its constituent traits in desert ferns of North America? This work aims to also bridge generational gaps in technical expertise among next-generation researchers for a variety of cutting-edge and classical approaches, thereby stimulating interdisciplinary student-driven research that emphasizes the value and relevance of museum specimens for addressing fundamental biological questions.
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