Polyps of the jellyfish Aurelia aurita are unaffected by chronic exposure to a combination of pesticides.

: Pesticides are a major contaminant in coastal waters and can cause adverse effects in marine invertebrates such as jellyfish. Most studies have investigated short-term responses of organisms to unrealistically high concentrations of pesticides; however, chronic exposure to persistent low concentrations, which are more likely to occur in the environment, are rarely analyzed. Here, we tested the response of polyps of the Moon jellyfish Aurelia aurita, to environmental concentrations of the herbicide atrazine and the insecticide chlorpyrifos, individually and in combination, over nine weeks. We hypothesized that exposure to individual pesticides would reduce rates of asexual reproduction and alter polyps' metabolite profiles, and that the results would be more severe when polyps were exposed to the combined pesticides. Polyps survived and reproduced (through budding) in all treatments and no differences among treatments were observed. Proton nuclear magnetic resonance (1 H NMR) spectroscopy revealed no difference in profiles of polar metabolites of polyps exposed to the individual or combined pesticides. Our results suggest that A. aurita polyps are unaffected by chronic exposure to atrazine and chlorpyrifos at concentrations recommended as being protective by current Australian water quality guidelines. This article is protected by copyright. All rights reserved.