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<p>Wildfire ash deposited in soils can represent a diffuse aquatic pollution. While most studies have focused on the acute toxicity of wildfire ash, its sublethal effects on key biological traits of freshwater organisms remain poorly understood. This study assessed the acute (48&#xa0;h) and chronic (21&#xa0;days) ecotoxicological effects of wildfire ash on <i>Daphnia magna</i> neonates. The acute test exposed 5 neonates per 50&#xa0;mL beaker to four ash concentrations (2.5, 5, 7.5, and 10&#xa0;g/L) and a control, assessing the lethal ash concentration (the median effective concentration, EC<sub>50</sub>). The chronic test exposed one neonate per beaker to three sublethal ash levels (0.8, 1.6, and 4.0&#xa0;g/L) and a control, evaluating morphology (body and spine size), life-history traits (longevity, reproduction), and locomotory behavior. The findings demonstrated that wildfire ash induces acute immobilization (EC₅₀ = 7.96 ± 0.66&#xa0;g/L) and significantly impairs longevity, growth, reproduction output, and behavior over time. Notably, the ingestion and accumulation of ash nanoparticles within the digestive tract were visually confirmed in exposed individuals, providing direct evidence of an exposure pathway rarely documented for wildfire ash. The Integrated Biomarker Response index (IBRv2) revealed that body width and locomotory behavior are particularly responsive biomarkers for detecting ash-induced sublethal stress. These findings indicate that wildfire ash is a complex aquatic contaminant, and even sublethal ash levels can interfere with essential biological functions in freshwater zooplankton, potentially causing cascading effects on aquatic food webs.</p> Graphical Abstract <p></p>

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Effects of Acute and Chronic Exposure to Grassland fire Ash on Life-History Traits and Locomotion of Daphnia magna

  • 期刊论文

  • 发表日期：

    2026年1月8日

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  • Ronnilda M. G. Araujo,
  • Jonatham H. S. Maciel,
  • Lucas G. Miguel,
  • Bethania Schimidt,
  • Bianca V. C. Oscar,
  • William G. Matias,
  • Bruno R. S. Figueiredo

摘要

Wildfire ash deposited in soils can represent a diffuse aquatic pollution. While most studies have focused on the acute toxicity of wildfire ash, its sublethal effects on key biological traits of freshwater organisms remain poorly understood. This study assessed the acute (48 h) and chronic (21 days) ecotoxicological effects of wildfire ash on Daphnia magna neonates. The acute test exposed 5 neonates per 50 mL beaker to four ash concentrations (2.5, 5, 7.5, and 10 g/L) and a control, assessing the lethal ash concentration (the median effective concentration, EC50). The chronic test exposed one neonate per beaker to three sublethal ash levels (0.8, 1.6, and 4.0 g/L) and a control, evaluating morphology (body and spine size), life-history traits (longevity, reproduction), and locomotory behavior. The findings demonstrated that wildfire ash induces acute immobilization (EC₅₀ = 7.96 ± 0.66 g/L) and significantly impairs longevity, growth, reproduction output, and behavior over time. Notably, the ingestion and accumulation of ash nanoparticles within the digestive tract were visually confirmed in exposed individuals, providing direct evidence of an exposure pathway rarely documented for wildfire ash. The Integrated Biomarker Response index (IBRv2) revealed that body width and locomotory behavior are particularly responsive biomarkers for detecting ash-induced sublethal stress. These findings indicate that wildfire ash is a complex aquatic contaminant, and even sublethal ash levels can interfere with essential biological functions in freshwater zooplankton, potentially causing cascading effects on aquatic food webs.

Graphical Abstract