Ecotoxicological Impact of the Marine Toxin Palytoxin on the Micro-Crustacean .

Palytoxin (PLTX) is a highly toxic polyether identified in various marine organisms, such as soft corals, dinoflagellates, and cyanobacteria. In addition to adverse effects in humans, negative impacts on different marine organisms have been often described during blooms and the concomitant presence of PLTX and its analogues. Considering the increasing frequency of blooms due to global warming, PLTX was investigated for its effects on a crustacean commonly used as a model organism for ecotoxicological studies. At concentrations comparable to those detected in culture media of cf. (1.0-10.0 nM), PLTX significantly reduced cysts hatching and induced significant mortality of the organisms, both at larval and adult stages. Adults appeared to be the most sensitive developmental stage to PLTX: significant mortality was recorded after only 12 h of exposure to PLTX concentrations > 1.0 nM, with a 50% lethal concentration (LC) of 2.3 nM (95% confidence interval = 1.2-4.7 nM). The toxic effects of PLTX toward adults seem to involve oxidative stress induction. Indeed, the toxin significantly increased ROS levels and altered the activity of the major antioxidant enzymes, in particular catalase and peroxidase, and marginally glutathione-S-transferase and superoxide dismutase. On the whole, these results indicate that environmentally relevant concentrations of PLTX could have a negative effect on population, suggesting its potential ecotoxicological impact at the marine level.