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Cross-taxa distinctions in developmental effects of trifluralin exposure between representative toxicological species for aquatic risk assessment
Citation:
Awkerman, J., C. Lavelle, W. Henderson, B. Hemmer, C. Lilavois, P. Harris, N. Zielinski, M. Hoglund, D. Glinski, D. Macmillan, J. Ford, R. Seim, E. Moso, AND S. Raimondo. Cross-taxa distinctions in developmental effects of trifluralin exposure between representative toxicological species for aquatic risk assessment. SICB Annual Meeting 2020, Austin, TX, January 03 - 07, 2020.
Impact/Purpose:
This product describes research comparing aquatic toxicity effects of trifluralin in fish and amphibians at the cellular and organismal levels with the goal of refining assumptions about representative toxicological test species and biochemical pathways impacted during development.
Description:
Standard ecological risk assessment practices often rely on larval and juvenile fish toxicity data as representative of the amphibian aquatic stage. Although empirical evidence suggests fish early life stage tests frequently are sufficiently sensitive to protect larval amphibians, the process of amphibian metamorphosis relies on endocrine cues that affect development and are responsible for morphological restructuring that does not occur in fish. Specifically, altered developmental effects can lead to detrimental impacts at the population level that are not captured in early life stage fish toxicity test endpoints. This study compares developmental endpoints for zebrafish (Danio rerio) and the African clawed frog (Xenopus laevis), two standard test species exposed to the herbicide trifluralin for 30 and 70 days, respectively. Zebrafish were more sensitive in acute toxicity and demonstrated a reduction in growth measurements with increasing trifluralin exposure. Growth measurements in X. laevis at metamorphosis were not correlated with exposure; however, time to metamorphosis was delayed relative to trifluralin concentration. Species-specific gene expression patterns suggest that different biological pathways in D. rerio and X. laevis are perturbed by trifluralin exposure. While many metabolites were positively or negatively correlated with exposure concentration, non-targeted hepatic metabolomics also identified a subset of metabolites that exhibited a non-monotonic response to trifluralin exposure in X. laevis. Linking differential cellular response with taxonomic distinctions in ecologically relevant endpoints will refine assumptions used in inter-species extrapolation of standard test effects, and interpretation of developmental effects in the context of altered vital rates, such as life stage transition, will improve assessment of sublethal impacts on amphibian populations.