NWT RESEARCH DATABASE

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area

Tags: physical sciences, climate change, limnology, permafrost degradation, sediment, environmental change

Objective(s): To continue to document and understand the impacts of recent climate change on northern terrestrial and aquatic ecosystems.

Project Description: This research will continue the long term objective of documenting and understanding the impacts of recent climate change on northern terrestrial and aquatic ecosystems. The short term objectives of my research for 2018 are: 1) to investigate the impacts of permafrost degradation and subsequent thaw slumping on freshwater ecosystems; 2) to examine the limnological implications of drained lakes on aquatic systems; and, 3) to examine impacts of recent climate change on the growth of white spruce in the regions around Inuvik and Norman Wells. The lake sediment sampling will occur during the late winter/early spring season and during mid-summer each year. The late winter/early spring field work (late March - early May; depending on weather) will occur while the lakes are still ice covered. The research team will target small lakes to recover long sediment records spanning the histories of these lakes. Using the ice cover as the coring platform the research team will use a Livingston piston corer or percussion type coring system to recover longer sediment profiles from these lakes. These coring systems allow the team to collect several metres of sediment from lakes with depths varying from a few metres to 10-15 metres. A gas powered ice auger will be used to cut through the ice cover and will carry a spill cleanup kit with us at all times. Graduate students will examine these cores for their sub-fossil diatom and pollen assemblages in addition to a number of sedimentological properties. Surface sediment cores from the bottom of each lake will also be obtained. A Glew gravity coring system will be used to recover undisturbed sediment profiles from the lake bottom. None of the coring systems used in this study will cause any significant disturbance to the lake bottom sediments. At each lake the team will also collect water samples to analyze for water chemistry. Within each proposed terrain unit (till plain, lacustrine and unglaciated) 1-2 lakes will be sampled. The research team will target lakes that are impacted by retrogressive thaw slumps at present to confirm the paleo proxy signature(s) that best characterizes thaw slumps in contemporary sediments. Based on the findings in recent sediments, the research team will apply those findings to older sediments from the Holocene to determine the occurrence and timing of thaw slump activity in the past. Specifically, the research team expect a change in particle grain size distribution and organic content due to the development of a retrogressive thaw slump along the shoreline of an impacted lake when the thaw slumps are active. The studies of contemporary sediments from north of Inuvik indicates this methodology is robust to capture these events in the past. Therefore, the research team expect that retrogressive thaw slumping in the past can be tracked using this proxy data source. The contemporary studies also indicate that dramatic changes in diatom communities can also occur in response to slumping. Therefore, the team will also rely on these biological indicators to track the occurrence of slumping during the Holocene. Particle grain size and organic content of the sediment will be used to estimate the timing of the onset and stabilization of permafrost slumps, as will the analysis of diatoms. Impacts at higher trophic levels of these aquatic systems (e.g., cladocera and chironomids) will also be examined. Near Inuvik, the research team have identified lakes affected by recent permafrost thaw slumps in the Noell Lake region (headwalls ~10 m high and several 100s of metres across) and are comparing these lakes to ones with no slumps. The team are examining the response of lakes in the different landscape types described above (organic rich lacustrine deposits; till plain and unglaciated terrain), to examine the nature of change experienced in these lakes due to 20th century warming. The other aspect of the research activities will focus on the examination of tree growth at several sites in the Inuvik and Norman Wells regions. Tree ring sites will be visited in these regions to develop long tree ring records spanning several centuries in time. At each site, approximately 30-50 trees will be sampled. A small core (4.3 mm in diameter) is removed from each tree. If dead snags or old logs are present on the ground, the team will cut a 1-inch thick cookie from these samples. In the case of dead standing snags the team will not disturb trees that appear to be nesting sites for any birds. The research team hope to reach some of the study sites by boat in the Mackenzie Delta. This will require assistance of an individual and a boat to reach those sites. With access to some sites now possible via the Inuvik-Tuktoyaktuk highway, an experienced guide and wildlife monitor will be requested when we visit those sites. To communicate the research results to the nearby communities, the research team will submit all theses and publications to the library at the Aurora Research Institute. The team will also communicate the results via northern meetings such as the Geoscience Forum and the Cumulative Impacts Monitoring Program Results Workshop. As always, the research team are happy to give community presentations in any of the local communities while in town. Additionally, the team are happy to work with school children or college students to teach them more about the work. The fieldwork for this study will be conducted from March 19, 2018 to December 31, 2018.