Grant: Discovery Grants Program - Northern Research Supplement

In water-rich northern landscapes there is a reciprocal relationship between permafrost and lake ecosystems. Lakes are altered by the thaw of permafrost in their catchments, and in turn influence permafrost landscape development. Where permafrost is rich in ice, retrogressive thaw slumping is one of the most important modes of permafrost thaw impacting freshwaters. In the Tuktoyaktuk Coastal Plains of Canada's western Arctic the nature of thaw slumping and limnological impacts are complex, including a range of disturbance phases where new slumps form, then stabilize, and may re-activate again and again, over centuries to millennia. My previous research has allowed my students, colleagues, and me to develop a conceptual model of how thaw slumps behave and impact lakes as part of a novel disturbance regime framework, incorporating the ecological memory within lakes associated with previous thaw slumping impacts. It is only within this framework that we can understand how the landscape will continue to evolve as climate warming accelerates. This proposal will explicitly test the conceptual model we have developed to fully understand the trajectory of lake ecosystem change associated with cyclical thaw slump impacts, contributing to greater understanding of the response of lakes to permafrost thaw slumping over long time scales. The objectives of this research will assess the initial formation of a new thaw slump when the impacts appear the most intense and track long-term cycles of slump impacts and the trajectories of lake ecosystem change and recovery. Observations over the last 15 years have shown that some lakes are now being impacted by more intense, enhanced thaw slump effects related to the acceleration of regional climate warming. My HQP trainees will specifically target these enhanced slumps to understand future climate warming and the impacts to aquatic ecosystems through intense landscape disturbance. The proposed research will assess the influence of lakes on thaw slump activity and re-activation, contributing to a better understanding the reciprocal relationship between permafrost thaw and surface waters. To address these research priorities projects will use geomatics, assessment of lake and catchment physical characteristics using bathymetric and LiDAR sensors, and lake sediment cores to infer past physical, chemical, and biological conditions in lake ecosystems over millennial timescales. The proposed research program will train graduate and undergraduate student researchers in understanding the ecosystem impacts of landscape disturbance in rapidly changing, northern regions of Canada. This work will contribute to an understanding of the relationship between thermokarst and lakes across the Northwest Territories being carried out by myself and my collaborators. The outcome of this understanding has local, regional, and global consequences for understanding climate change and permafrost thaw.