From exposure to effect: Exploring adverse outcome pathways in fish responses to a large mining disaster

Area of Science:

• Environmental Science
• Ecotoxicology
• Biomonitoring

Background:

• Long-term environmental monitoring generates complex data.
• Understanding toxicant impacts requires integrated frameworks.
• The 2015 Brazil tailings dam collapse provides a case study for assessing environmental recovery.

Purpose of the Study:

• To develop and apply a novel framework combining Adverse Outcome Pathways (AOPs) and probabilistic causal modeling for interpreting environmental monitoring data.
• To assess the impact of metal(loid) toxic pressure on aquatic ecosystems post-tailings dam collapse.
• To link sub-individual biomarker responses to population-level outcomes like fish growth.

Main Methods:

• Integrated metal(loid) concentrations into a toxic pressure index across river-to-sea gradients.
• Utilized piecewise structural equation mixed-effects models within the AOP framework.
• Analyzed six years of data (2018-2024) including water chemistry, fish bioaccumulation, and sub-individual biomarkers.

Main Results:

• Toxic pressure decreased from river to sea, with higher metal(loid) levels in freshwater.
• Biomarker responses (metallothionein, lipid peroxidation, lesions) correlated with toxic pressure in rivers but were weaker in marine environments.
• Tissue damage (lesions) linked to oxidative stress and negatively impacted fish condition index, indicating potential growth impairment.

Conclusions:

• The AOP-causal modeling framework effectively structures and interprets complex environmental data.
• Biological responses to mixed-metal exposure are context-dependent and influenced by species and temporal variability.
• Integrated monitoring approaches are crucial for understanding ecological impacts and informing environmental management.