Combined effects of polystyrene microplastics and copper on antioxidant capacity, immune response and intestinal microbiota of Nile tilapia (Oreochromis niloticus)

Microplastics (MPs) coexist with other pollutants (such as heavy metals) in water, adversely impacting aquatic organisms, which might cause unpredictable ecological risks. This study aims to evaluate the effect of copper (Cu2+) and polystyrene microplastics (PS-MPs) on antioxidant capacity, immune response and intestinal microbiota of Nile tilapia. Cu2+ and PS-MN co-exposure enhanced Cu2+ bioaccumulation in the liver of fish compared with Cu2+-alone exposure. Fish exposed to PS-MPs and Cu2+ displayed histopathologic alterations in the liver, intestine and gill. Exposure at low concentrations of Cu2+ in the CO and CPO groups can improve antioxidant capacity and immune response, while oxidative damage and inflammation existed in the high concentration of Cu(2+ )groups. Intestinal microbiota results showed that the diversity and structure were changed by Cu2+ and PS-MN exposure, and harmful bacterium even increased at high concentration of Cu2+ and PS-MPs exposure groups. All in all, PS-MPs aggravate the accumulation of Cu2+ and lead to perturbations in biological systems of Nile tilapia.