Antioxidant cellular response of the soft coral Pinnigorgia flava after exposition to polypropylene nanofibers and polypropylene nanofibers leachate

After the spreading of COVID-19, the amount of plastics in the ocean was severely enhanced due to the increased production of PPE, in particular surgical masks. Once entered into the environment, these disposable items can both release potential toxic additives and undergo fragmentation leading to the formation of microplastics and nanoplastics. Moreover, microplastics and nanoplastics are considered the most harmful for corals and marine organisms since can easily be ingested. Current information regarding the effects of micro and nanoplastics on coral reefs is limited; especially the toxicity of nanoplastics and nanoplastics leachate from fibers degradation of synthetic fabrics. The alcyonacean was exposed for 72 h to different concentrations of polypropylene nanofibers (0.1 and 1 mg/L) and nanofibers leachate (0.1 and 1 mg/L) under controlled aquaria conditions. The cellular response was assessed through antioxidant enzymatic assays, namely Superoxide Dismutase (SOD), Catalase (CAT), Glutathione Reductase (GR), and Glutathione-S-Transferase (GST). Results showed that for all treatments, oxidative stress was experienced in all samples. However, different patterns of enzymatic activity were observed between nanofibers and leachates, with a general higher toxicity generated by leachates exposition that produced an inhibition and/or impairment of the antioxidant defense mechanisms at cellular level. This study represents a new area of investigation and is one of the first to focus on such stressors on soft coral species. In addition, the results highlight that nanofibers and leachates are indeed a major threat for coral reefs, which are already exposed to multiple climate change stressors and relentless anthropogenic pressures.