Effects of benzodiazepine delorazepam on Mytilus galloprovincialis

Psychoactive compounds, and benzodiazepines BZPs in particular, represent an important class of emerging pollutants due to their large (ab)use and high resistance to degradation. It is widely reported that sewage treatment does not completely eliminate these substances and, therefore, BZPs and their metabolites reach concern levels in most aquatic environments of all over Europe, ranging from µg/L to ng/L. Bioaccumulation is already reported in fish and small crustaceans with significant effects on behavior, gene expression and enzymes activity. In this study we investigated the effects of delorazepam on Mytilus galloprovincialis, a model organism in toxicity testing and a key species in coastal marine ecosystems. Given its psychoactive activity, the study was primarily addressed at discovering the effects on behavior, by conventional valve opening and closure tests. Possible cytotoxic activity on valve abductor muscles was also investigated together with oxygen consumption so to correlate valve and muscle activity changes with variation in metabolism. Preliminary results indicated that environmental concentrations of delorazepam negatively affects mussel behavior and, by reducing metabolism, they seriously increase predation risk. Studies also indicate that delorazepam alters gill morphology and protein content. In conclusion, data support what already reported in literature, i.e., that BZDs affect the behavior of aquatic species with consequent effects on predator-prey interactions. Ultimately, the structure of the food web and the functions of the ecosystem may be affected.