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Item Open Access Long-term ecological change in Lake Scugog (Ontario) inferred from lake sediment cores: Current ecosystem changes in Lake Scugog evaluated in an historical context.(2023-02-15) Korosi, Jennifer; Thienpont, Joshua; Adano, Randelle; Do, Pham Ha Phuong; Jeyarajah, JanujaIn 2017, the Scugog Lake Stewards were awarded an Ontario Trillium Foundation Grow Grant to study the ecology of Lake Scugog, to provide insights into ecosystem stressors that present a challenge to walleye conservation and lake restoration. As part of this, York University initiated a paleolimnological study, led by Profs. Korosi and Thienpont, to document the ecological changes that have occurred in Lake Scugog since it was formed in the mid-19th century following the construction of the Lindsay Dam. Sediment cores were collected from two locations: (1) the deepest point of the eastern arm of the lake, and (2) near the town of Port Perry. The original objective of this study was to infer long-term trends in lake habitat, food web structure, thermal regime, productivity, and oxygen using fossil remains of three different groups of ecological indicators (diatoms, chironomids, and Cladocera) and nitrogen stable isotopes. A secondary objective, to infer long-term trends in cyanobacteria in Port Perry Bay was added to the project after Microcystis blooms were documented in 2017 by Ontario Tech University.Item Open Access Dataset: A decadal perspective on permafrost thaw slump disturbances on Arctic upland lakes in the Mackenzie Delta region (Northwest Territories, Canada)(2022-10) Thienpont, Joshua; O'Hagan, Claire; Hoskin, Grace; Kokelj, Steve; Korosi, JenniferRetrogressive thaw slumps are the dominant thermokarst landscape disturbance in regions of ice-rich permafrost. The impact of thaw slumps on the water and sediment chemistry and aquatic biology of lakes of the Tuktoyaktuk Coastlands has been explored for almost 2 decades. This corresponds to a period of accelerated warming and an intensification of thaw-driven mass wasting. Past research in the region provides a basis for developing a relatively long-term perspective on limnological changes associated with thaw slump activity. Here we revisit lakes sampled previously, to investigate if water chemistry parameters have changed with thaw-related catchment characteristics. We combined re-sampling of water chemistry (48 lakes) with remotely-sensed image-derived characterization of thaw slump activity (66 lakes) to provide a decadal perspective on changes in the Mackenzie Delta region. Our data showed that four thaw slumps that were stable in 2005 had active slumps that had reinitiated, five lakes with active slumps in 2005 had since stabilized, and two lakes previously classified as reference now have active slumping. Water chemistry variables associated with slump activity (e.g., conductivity, major ion concentrations) were slightly lower in most lakes (likely due to sample timing), but increased in lakes with the greatest thaw slump growth. In several lakes with slumps that had stabilized over the last decade, conductivity decreased >20%, suggesting recovery may be occurring. This research provides a decadal perspective on the linkage between intense landscape disturbance and limnological change in one of the most rapidly warming regions on Earth.Item Open Access Limnology and diatom ecology of shallow lakes in a rapidly thawing discontinuous permafrost peatland(2023-01-01) Coleman, Kristen; Korosi, JenniferLimnological data for small, shallow lakes at or near the Scotty Creek Field Station near Fort Simpson, Northwest Territories, Canada. It includes: (1) surface water chemistry and subfossil diatom (Bacillariophyta) assemblages in 16 lakes at or near Scotty Creek collected in mid-July, 2018; (2) high-resolution logger data for depth, oxygen, light, and temperature profiles over the 2019 ice-free season in First Lake and Goose Lake at the Scotty Creek Research Station; (3) buffer and overlay landscape analysis of fen and collapse scar area within a 250 m buffer of lake shorelines for 9 lakes in the Scotty Creek basin; (4) Water chemistry and subfossil diatom assemblages in wetlands and substrate samples (submerged vegetation, submerged peat, sediment, and grasses) from shoreline environments around Goose Lake, collected in June, 2019. Data accompanies Kristen Coleman’s PhD dissertation (York, Geography).Item Open Access Dataset: Climatic Drivers of Limnological Change in Iqallukvik Lake, Tuktoyaktuk, Northwest Territories, Canada(2022) Gruia, Sorin-Alexandru; Thienpont, Joshua; Coleman, Kristen; Korosi, Jennifer