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 this research 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 the impacts of dust on freshwater lakes using small lakes/ponds along the Dempster Highway near Fort McPherson as the study sites. 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 April - early May) will occur while the lakes are still ice covered. Small lakes will be targeted 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 Livingstone piston corer or percussion type coring system to recover longer sediment profiles from these lakes. These coring system allows 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 a spill cleanup kit will be carried at all times. These cores will be examined for their sub-fossil diatom assemblages. 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. Based on the findings in recent sediments, the 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, a change in particle grain size distribution and organic content is expected, 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 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 research 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 (J. Thienpont and student TBD). Near Inuvik, lakes affected by recent permafrost thaw slumps have been identified in the Noell Lake region (headwalls ~10 m high and several 100s of metres across) and are compared to ones with no slumps. To examine the impacts of road dust on these small lakes/ponds, sediment cores will be collected from lakes along the Dempster Highway west of Fort McPherson. During the summer months these lakes receive inputs of dust as traffic moves along the Dempster. The impact that this dust has on the lake systems has not been investigated previously. The research team will examine algae (e.g., diatoms) from these lakes during the past 100 years to determine if the construction of the Dempster Highway impacted the algal communities and the rate at which sediment has accumulated in the lakes. 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. The research team are happy to give community presentations in any of the local communities. 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 April 16, 2017 to August 18, 2017.