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In this study, we screened eight terpenes isolated from the organic extract of Sphaerococcus coronopifolius for their antifouling activity in order to find possible new sources of non-toxic or less toxic bioactive antifoulants. The anti-settlement activity (EC₅₀) and the degree of toxicity (LC₅₀) of S. coronopifolius metabolites was evaluated using larvae of the cirriped crustacean Amphibalanus (Balanus) amphitrite (cyprids and nauplii) as model organism. For five of eight tested metabolites EC₅₀ was lower than 5 mg/L. The most promising results were observed for bromosphaerol (3), which expressed an EC₅₀ value of 0.23 mg/L, in combination with low toxicity levels (LC₅₀ > 100 mg/L). The therapeutic ratio--an index used to estimate whether settlement inhibition is due to toxicity or other mechanisms--is also calculated and discussed.

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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 dosedependent effect, and for each end-point, it was possible to quantify these effects by means of EC 50 . 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.