Impacts of subchronic exposure to a commercial 2,4-D herbicide on developmental stages of multiple freshwater fish species

• Published in: Chemosphere (Oxford) 2021-01, Vol.263, p.127638, Article 127638
• Main Authors: Dehnert, Gavin K., Freitas, Mariella B., Sharma, Prashant P., Barry, Terence P., Karasov, William H.
• Format: Article
• Language: English
• Subjects: 2,4-D; 2,4-Dichlorophenoxyacetic Acid - toxicity; Animals; Developmental toxicology; Ecosystem; Ecotoxicology; Fresh Water; Herbicides; Herbicides - analysis; Herbicides - toxicity; Humans; Larval fish; Phylogeny; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - toxicity
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.127638

Invasive, nuisance aquatic species such as Eurasian watermilfoil (Myriophyllum spicatum) are rapidly spreading across the United States. One common active ingredient used to control this invasive species is 2,4-Dichlorophenoxyacetic acid (2,4-D). Application of 2,4-D to aquatic environments typically occurs while many freshwater fish are spawning and due to 2,4-D stability in aquatic environments, many non-target species experience prolonged exposure throughout embryogenesis and larval development. The impacts of 2,4-D exposure on phylogenetically distant fish species is poorly understood. Herein, we investigated the impacts of the 2,4-D commercial herbicide DMA4®IVM on nine freshwater fish species from six different families (four orders) at different points during ontogeny. Each species was exposed to ecologically relevant concentrations of a commercial 2,4-D herbicide (0.05, 0.50, and 2.00 ppm or mg/L 2,4-D a. e.), and effects on morphology, survival, and growth were evaluated. Our results demonstrate that exposure of embryonic and larval fish to ecologically relevant concentrations of a commercial 2,4-D herbicide reduced survival in early developmental stages of six freshwater species that spanned five phylogenetic families and three phylogenetic orders; however, sensitivity to 2,4-D exposure did not show correlation with phylogenetic proximity. Altogether, our results indicate that the use of 2,4-D herbicides in aquatic ecosystems at current recommended concentrations (≤2 ppm whole-lake treatment) could present risk to multiple freshwater fish species survival during early development. [Display omitted] •Ecologically relevant concentrations of 2,4-D reduced survival in six fish species.•2,4-D reduced survival in species from 5 families and 3 orders.•Sensitivity to 2,4-D exposure did not show correlation with phylogenetic proximity.•Early developmental stages are more at risk to 2,4-D exposure than juvenile fish.