Comparison of fitness effects in the earthworm Eisenia fetida after exposure to single or multiple anthropogenic pollutants

• Published in: The Science of the total environment 2022-09, Vol.838 (Pt 3), p.156387-156387, Article 156387
• Main Authors: Holzinger, Anja, Mair, Magdalena M., Lücker, Darleen, Seidenath, Dimitri, Opel, Thorsten, Langhof, Nico, Otti, Oliver, Feldhaar, Heike
• Format: Article
• Language: English
• Subjects: Brake dust; Carbon black; Fine particulate matter; Microplastic; Multiple stressors; Soot
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.156387

Terrestrial ecosystems are exposed to many anthropogenic pollutants. Non-target effects of pesticides and fertilizers have put agricultural intensification in the focus as a driver for biodiversity loss. However, other pollutants, such as heavy metals, particulate matter, or microplastic also enter the environment, e.g. via traffic and industrial activities in urban areas. As soil acts as a potential sink for such pollutants, soil invertebrates like earthworms may be particularly affected by them. Under natural conditions soil invertebrates will likely be exposed to combinations of pollutants simultaneously, which may result in stronger negative effects if pollutants act synergistically. Within this work we study how multiple pollutants affect the soil-dwelling, substrate feeding earthworm Eisenia fetida. We compared the effects of the single stressors, polystyrene microplastic fragments, polystyrene fibers, brake dust and carbon black, with the combined effect of these pollutants when applied as a mixture. Endpoints measured were survival, increase in body weight, reproductive fitness, and changes in three oxidative stress markers (glutathione S-transferase, catalase and malondialdehyde). We found that among single pollutant treatments, brake dust imposed the strongest negative effects on earthworms in all measured endpoints including increased mortality rates. Sub-lethal effects were found for all pollutants. Exposing earthworms to all four pollutants simultaneously led to effects on mortality and oxidative stress markers that were smaller than expected by the respective null models. These antagonistic effects are likely a result of the adsorption of toxic substances found in brake dust to the other pollutants. With this study we show that effects of combinations of pollutants cannot necessarily be predicted from their individual effects and that combined effects will likely depend on identity and concentration of the pollutants. [Display omitted] •Brake dust, carbon black, microplastic fragments & fibers have sublethal effects on earthworms.•Brake dust imposes strongest negative effects including increased mortality rates.•Exposure to the four pollutant mixture leads to smaller effects than expected.•Effects of multiple stressors are complex & likely depend on pollutant type.