Long-term aquatic ecosystem change at the southern limit of permafrost
Principal Investigator: Korosi, Jennifer B (8)
Licence Number: 16439
Organization: York University
Licensed Year(s): 2019 2018
Issued: Dec 16, 2018

Objective(s): To examine chemical and biological fossil remains preserved in lake sediment cores, in order to better understand how thawing permafrost impacts lake ecosystems.

Project Description: The goal is to reconstruct long-term environmental change (hundreds to thousands of years) by examining chemical and biological fossil remains preserved in lake sediment cores, in order to better understand how thawing permafrost impacts lake ecosystems. 1) Water chemistry and plankton survey The research team will collect lake water samples from the study lakes to analyze for water chemistry parameters (e.g. organic carbon, nutrients, conductivity). A probe will be used to measure lake pH, dissolved oxygen, and temperature directly on site. Plankton (microscopic algae and floating crustaceans) will be collected from the water column using a standard plankton net tow, preserved, and shipped back to York University to be identified under a microscope. The lake survey (water chemistry and plankton) will allow the team to examine how present-day lake conditions vary across the region. Using multi-variate statistics, the team will identify the main drivers of regional variation, with a focus on watershed characteristics, especially estimates of the extent of permafrost thaw derived from satellite imagery. 2) Lake sediment coring (paleolimnology) The research team will collect surface sediment cores (~30-50cm in length) from the bottom of the lakes using a Uwitec gravity corer, which will incorporate the last several hundred years of lake history. Sediment cores will be shipped back to York University, where they will be analyzed for biological fossil remains (algae, zooplankton, macroinvertebrates), charcoal (as an indicator of past fire events), and chemical attributes (algal pigments to infer primary production, organic matter biomarkers, metals, carbon and nitrogen isotopes). Organic matter biomarkers provide information on the sources of organic matter to lakes (e.g. terrestrial vs. aquatic, trees versus mosses), and are useful for denoting the timing of landscape changes due to permafrost thaw. The sediment cores will provide a detailed reconstruction of how the lake ecosystem has changed over the last several hundred years in response to a warming climate and thawing permafrost. The Uwitec coring systems used in this study will not cause any significant disturbance to the lake bottom sediments. The research team are happy to give presentations on our research to local schools and/or community meetings, or any other interested group. The research team would also be happy to work with school children to provide hands-on teaching on our research and sampling methods, if there was interest. As well, as this is the first field season in a multi-year project, the team would welcome opportunities for community consultation to discuss potential future study lakes and possible synergies between our interests and community knowledge priorities. The research team will prepare plain-language reports annually summarizing the research progress. The team will submit all theses and publications arising from the research to the Aurora Research Institute. The team will also communicate the results at the Yellowknife Geoscience Forum, and are happy to give community and/or school presentations, if there is interest. The fieldwork for this study will be conducted from May 15, 2019 to August 30, 2019.