Assessing recovery in storm surge impacted lakes of the outer Mackenzie Delta, NT, Canada

Abstract

Low-lying ecosystems within Canada’s Arctic regions have experienced an increased frequency and intensity of storm surge events in recent decades, due to the impacts of anthropogenic climate changes. Following a severe storm surge that took place in September 1999, lakes in the northwest Mackenzie Delta (NT, Canada) were fundamentally altered. Lake sediment cores were collected a decade after the event for paleolimnological analysis, revealing that some lakes had undergone complete or partial transition to brackish environments. However, the condition of the lakes had not been assessed in the last 15 years, and it is unknown if the lakes have recovered, remain highly disturbed, or have been impacted by subsequent storm surge events. The purpose of this study was to assess recent ecosystem trajectories in storm surge-impacted lakes of the outer Mackenzie Delta using contemporary water chemistry and paleolimnological analyses of sedimentary diatom assemblages. Findings indicate that recovery trajectories vary substantially among lakes, largely due to the spatially heterogeneous and non-linear nature of recovery from saltwater intrusion in Arctic coastal ecosystems. Differences in recovery trajectories emphasize the importance of local hydrology, landscape position, and lake-specific characteristics in determining ecosystem resilience. As climate change continues to increase the likelihood of coastal flooding and storm surge events across the Arctic, understanding these recovery processes will be critical for predicting future ecological change in northern deltaic environments.