1H NMR metabolomics of earthworm responses to sub-lethal PAH exposure

Environmental context. Polycyclic aromatic hydrocarbons (PAHs) are common contaminants, but there has been limited research investigating the responses of earthworm exposure to sub-lethal PAH concentrations. In this study, 1H nuclear magnetic resonance (NMR) metabolomics was used to characterise the metabolic responses of Eisenia fetida earthworm exposure in contact tests to 10, 50 and 100 μg cm–2 naphthalene, phenanthrene and pyrene. The findings of this study highlight the potential of metabolomics as a tool for monitoring earthworm responses to sub-lethal concentrations of problematic environmental contaminants. Abstract. Metabolic responses of earthworm exposure to the polycyclic aromatic hydrocarbons (PAHs) naphthalene, phenanthrene and pyrene in contact tests were measured using 1H nuclear magnetic resonance (NMR). Novel metabolites were not detected but principal component analysis (PCA) showed that earthworms exposed to 10, 50 and 100 μg cm–2 naphthalene, phenanthrene and pyrene differed from unexposed (control) earthworms. Partial least-squares-discriminant analysis (PLS-DA) showed that earthworms had statistically significant responses to PAH exposure, except for 10 μg cm–2 naphthalene and 50 μg cm–2 pyrene. Leucine, valine, alanine, lysine and maltose were identified as potential response indicators of PAH exposure, but whether the concentration of these metabolites increased or decreased was PAH- and concentration-dependent. These initial findings reveal the potential of metabolomics for monitoring earthworm responses to sub-lethal PAH exposure and highlight the role of metabolomics as a future tool in ecotoxicology.