Chronic toxicity of ZnO nanoparticles: effects on survival and reproductive traits of the marine copepod Tigriopus fulvus

The use of biological models has been recognized as very important in nanoecotoxicology for the understanding of Nanoparticle (NP) ecotoxicological effects. This study aimed to assess, for the first time, the chronic toxicity of Zinc Oxide NPs (ZnO NPs) on survival and reproductive traits of the marine copepod Tigriopus fulvus. Moults number, sex ratio, developmental time of nauplius and copepodid, fecundity and hatching time were assessed as sublethal endpoints. The results showed significant effects of ZnO NP exposure on all reproductive traits if compared to the control (seawater without ZnO NPs). The mean number of nauplii per brood was significantly reduced already (p<0.05) at 0.10 mg/L and even fecundity (as mean total number of nauplii per female) was significantly reduced at all ZnO NPs concentrations. A reduced number of broods per female were recorded at all nZnO concentrations (0.05-0.1-0.15-0.2-0.25 mg/L), compared to control (6.7±0.2), with the lowest value (2.8±0.3) at the highest concentration (ANOVA, p<0.05). This study evidenced the toxicity of ZnO NPs and the capacity to inhibit the reproductive activity of the marine copepod T. fulvus. These results highlight the intrinsic risk in the use and disposal of manufactured nanomaterials, as well as the importance of the research on the NP toxicity to enhance risk management. Given the lack of reliable information on ecological hazards and consequences of ZnO NPs, and particularly on its chronic toxicity to marine species, a better and relevant understanding of the effects represents a priority.