Zebrafish Embryo Model as a Tool for Ecotoxicological Studies in Central Italy's Transitional Waters

Thousands of chemical pollutants are commonly widespread in European water bodies. The Water Framework Directive obliges the European Member States to monitor and assess waterbodies quality to minimize the adverse effects of such pollution on ecosystems and human health. In this context, Effect-based methods represent key tools for investigating the potential impacts of water pollution on ecosystems as they provide essential information on different chemical modes of action and their related effects on living organisms. In this study, we used the Fish Embryo Acute Toxicity test with the zebrafish model to analyze transitional and artificial waterbodies of the Tyrrhenian coastal area in Central Italy. Five samples were collected in a highly populated coastal area in two different periods of the year. Both lethal and sublethal effects across 96 hours of exposure post-fertilization were assessed. All the samples showed high acute toxicity within 96 hours of exposure, leading to increased mortality rates (>30%) and sublethal effects on embryos. Overall, different sublethal endpoints were observed such as spine deformation, unhatched embryos, depigmentation, and pericardial oedema. Comparing the sampling campaigns, a significant difference between mortality rates was detected for two samples, potentially indicating the influence of seasonality in the chemical fingerprinting. The use of the zebrafish model has confirmed to be a very sensitive tool in environmental monitoring closely linked with human health. Our findings might be further investigated to better understand the potential risks for the environment and human health within the study area.