Immunotoxicity and oxidative damage in Litopenaeus vannamei induced by polyethylene microplastics and copper co-exposure

Abstract

This study examines the combined effects of polyethylene microplastics (PE-MP) and copper (Cu²⁺) on the immune and oxidative response of Litopenaeus vannamei. PE-MP adsorbed with Cu²⁺ at 2.3, 6.8, and 16.8 ng (g shrimp)^-1) were injected into L. vannamei. Over 14 days, survival rates were monitored, and immune and oxidative stress parameters were assessed. The results showed that combined exposure to PE-MP and Cu²⁺ significantly reduced the survival rate and decreased total haemocyte count. Immune-related parameters (phagocytic rate, phenoloxidase and superoxide dismutase (SOD)) and antioxidant-related parameters (SOD, catalase and glutathione peroxidase mRNA and enzyme) also decreased, while respiratory burst activity significantly increased, indicating immune and antioxidant system disruption. Additionally, there was a significant increase in oxidative stress, as measured by malondialdehyde levels. Histopathological analysis revealed severe muscle, hepatopancreas, and gill damage. These results suggest that simultaneous exposure to PE-MP and Cu²⁺ poses greater health risks to white shrimp.

Keywords: Aquatic organisms; Heavy metals; Histopathology damage; Immune disruption; Microplastics; Oxidative stress.