Rapid and Long-Term Environmental Changes and the Status of Biodiversity in the Canadian Beaufort Sea Ecosystem
Date: Thursday, September 12, 2024
Time: 1:00 PM
Location: AERL 107, 2202 Main Mall.
Climate change is impacting Arctic marine ecosystems, challenging their management and conservation, with consequences for Indigenous Inuit communities. This thesis aims to describe the ecosystem dynamics of the Canadian Beaufort Sea and Amundsen Gulf, including the Tarium Niryutait and Anguniaqvia niqiqyuam Marine Protected Areas (MPAs) to better understand climate risks and vulnerabilities, and inform actions for mitigation and adaptation. Using the food web modeling platform Ecopath with Ecosim, I compared the Beaufort Sea shelf between 1970– 1974 and 2008–2012, and against four high latitude ecosystem models to understand how changing ocean conditions are affecting these ecosystems. I found that the biomass of lower trophic levels of the Beaufort Sea shelf increased over time, pointing to increases in primary production, driving the amount of food available for higher-order consumers. Estimates of trophic structure proved stable over time, indicating that modeled climate-related drivers may not have a large impact on overall structure. Next, individual and cumulative climate change effects represented as increased sea surface temperature, reduced sea ice extent, ocean deoxygenation, and ocean salinity in the region were modeled and compared (1970–2021), drawing on simulations from two coupled Earth system models. I found that including the effects of modeled salinity substantially impacted physiological rates and bioenergetics of fish, reducing ecosystem diversity of the Beaufort Sea shelf and slope, resulting in changes to trophic levels, biomass, and consumption rates of key species. Lastly, the nature of climate hazards from these changing ocean conditions, including acidification, were projected using a regional coupled ice-ocean biogeochemical model and two Earth system models to 2050 under low and high emissions scenarios. Spatially-explicit algorithms were used to compute risk and vulnerability indices based on species’ biological traits and exposure to climatic hazards. Results indicated that species with limited plasticity and the MPAs at high risk from more intense warming, reduced sea ice coverage, and increased salinity and pH relative to regional averages. Findings from this modelling work highlight important dynamics to consider for marine spatial planning under climate change, and challenges/opportunities for achieving conservation and socio-economic objectives for MPAs, and dependent Indigenous communities into the future.
Supervisor: Dr. William Cheung
Examination Committee Members: Dr. Carie Hoover
University examiners: Dr. Marie Auger-Méthé, Dr. Stephanie Waterman
External examiner: Dr. Franz Mueter
Exam chair: Dr. Michael Tenzer