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Repeated pollution exposure magnifies the escape behaviour in the avoidance test with enchytraeids
Janeck J Scott-Fordsmand1, Marija Kovačević2, Branimir K Hackenberger2
1Department of Ecoscience, Aarhus University, C.F. Møllers Alle, DK-8000, Aarhus, Denmark.
Environmental Research
|August 2, 2025
Summary
Earthworms exposed to silver nanomaterials learned to avoid contaminated soil with repeated encounters. Organisms that did not initially avoid the contaminant showed no change in behavior over time.
Area of Science:
- Environmental Science
- Ecotoxicology
- Soil Ecology
Background:
- Avoidance testing is a key soil ecotoxicity assay for earthworms.
- Limited understanding exists regarding long-term avoidance behaviors and adaptive learning in earthworms exposed to contaminants.
- Phenotypic plasticity in response to environmental stressors like nanomaterials requires further investigation.
Purpose of the Study:
- To investigate the influence of repeated exposure on the avoidance behavior of Enchytraeus crypticus to silver nanomaterials (Ag NM300K).
- To determine if organisms can learn to avoid contaminants through repeated encounters or phenotypic adaptation.
- To compare the behavioral responses of earthworms that initially avoid versus those that do not avoid contaminated soil.
Main Methods:
- Enchytraeus crypticus were subjected to repeated avoidance tests in soil contaminated with Ag NM300K.
- Populations were divided into 'Avoidance' (A) and 'Non-Avoidance' (Non-A) groups based on initial exposure.
- The A group consisted of individuals that avoided the contaminant in each successive test, while the Non-A group comprised individuals that did not avoid.
Main Results:
- Earthworms in the 'Avoidance' group demonstrated a significant increase in avoidance behavior with repeated exposures to silver nanomaterials.
- In contrast, the 'Non-Avoidance' group exhibited no significant change in avoidance behavior across subsequent exposures.
- This suggests a capacity for learned avoidance in this species under specific exposure conditions.
Conclusions:
- Repeated exposure can enhance avoidance behavior in Enchytraeus crypticus when encountering silver nanomaterial contamination.
- The capacity for learned avoidance appears dependent on the initial response to the contaminant.
- These findings have implications for understanding soil invertebrate responses to nanomaterial pollution and the potential for adaptation.
