Effect of neurotoxic compounds on ephyrae of Aurelia aurita jellyfish

The aim of this study was to analyze the toxicity of two neurotoxic compounds on the ephyra stage of the Scyphozoan jellyfish Aurelia aurita, an innovative and sensitive model organism recently proposed in ecotoxicological bioassays. Indeed, jellyfish play an important role in the marine ecosystem, being a key component of the gelatinous zooplankton and of the marine food web, but are not represented in routine ecotoxicology. In this study, ephyrae were exposed to several concentrations (0, 0.1, 0.5, 1, 5, 10, 50 mg l(-1)) of eserine (ES) and chlorpyrifos (CPF), a carbamate and an organophosphorous compound, respectively, in order to analyze their toxic effect on this model organism. Acute (% of immobility) and behavioral (% alteration of frequency of pulsations) end-points were investigated after 24 and 48 h of exposure. Exposure to both compounds caused a dose-dependent effect, and for each end-point, it was possible to quantify these effects by means of EC50. Results highlighted how these compounds reported a high toxicity for marine organisms and exerted their toxic effect on this innovative biological model (in particular, CPF resulted to be more toxic than ES), which proved to be more sensitive than other marine invertebrates commonly used for ecotoxicological bioassays.