Exploring Drivers of Historic Mercury Trends in Beluga Whales Using an Ecosystem Modeling Approach

Area of Science:

• Environmental Science
• Ecology
• Toxicology

Background:

• Human activities have altered mercury's natural cycle, leading to methylmercury formation in aquatic systems.
• Methylmercury is a potent neurotoxicant that bioaccumulates in organisms, posing risks to ecosystem and public health.
• Arctic beluga whales, important to Inuit communities, can accumulate high methylmercury concentrations.

Purpose of the Study:

• To investigate the drivers of methylmercury bioaccumulation in Beaufort Sea beluga whales.
• To explore the influence of climate change impacts on mercury levels in beluga whales.
• To integrate Western Science and Inuvialuit Knowledge in ecosystem modeling for contaminant cycling.

Main Methods:

• Utilized Ecopath with Ecosim (EwE), an ecosystem modeling approach.
• Developed scenarios of environmental change, including sea ice cover, sea surface temperature, and freshwater discharge.
• Compared the effects of ecological changes versus direct mercury inputs on beluga methylmercury concentrations.

Main Results:

• Changes in ecosystem productivity, driven by environmental factors, better explained historical mercury fluctuations in beluga than mercury emission trends alone.
• Rising temperatures, sea ice melt, and altered freshwater discharge were identified as key environmental drivers.
• These drivers partially explained the observed decrease in beluga mercury concentrations after the mid-1990s.

Conclusions:

• Climate change impacts on ecosystem dynamics are significant drivers of methylmercury bioaccumulation in Arctic beluga whales.
• Integrating diverse knowledge systems and modeling approaches is crucial for understanding contaminant cycling under environmental change.
• Findings can inform climate adaptation strategies and management decisions for Arctic ecosystems and communities.