Climate Change and Marine Food Webs: Navigating Structural Uncertainty Using Qualitative Network Analysis With...

Area of Science:

• Ecology
• Climate Change Biology
• Conservation Science

Background:

• Modeling climate change impacts requires understanding ecosystem-wide effects.
• Shifts in species interactions and abundance due to climate change cascade through food webs.
• Cumulative impacts on conservation-reliant species necessitate explicit examination.

Purpose of the Study:

• To explore alternative responses to climate change across marine food webs using qualitative network analysis.
• To assess the impact of structural and quantitative uncertainties on salmon populations under climate change scenarios.
• To identify key interactions influencing salmon outcomes in a changing climate.

Main Methods:

• Utilized qualitative network models to test 36 plausible representations of salmon and marine food web interactions.
• Scenarios varied species pair connections (positive, negative, no interaction) and direct climate change responses.
• Analyzed how different food web configurations and climate perturbations affect salmon outcomes.

Main Results:

• Certain food web configurations consistently led to negative outcomes for salmon.
• Salmon outcomes worsened significantly (30% to 84% negative) when competitor and predator consumption increased due to climate perturbation.
• Feedbacks between salmon and marine mammals, and indirect effects between salmon runs, were critical.
• Identified specific links with strong influence on salmon outcomes across various scenarios.

Conclusions:

• Structural uncertainty in food webs is crucial for accurately modeling climate change impacts.
• Qualitative network analysis provides a valuable tool for exploring diverse climate change scenarios and uncertainties.
• Results aid in planning more targeted and effective research for salmon conservation.