Pollution in marine bivalves: The immunosuppressive effects of microplastics on Anadara granosa

Microplastics (MPs), as emerging marine pollutants, pose a significant threat to marine organisms and ecosystems. This study investigates the effects of 7-day MPs exposure on the immune response of the blood clam (Anadara granosa), a commercially valuable marine bivalve known for its filter-feeding and sedentary lifestyle, which renders it particularly vulnerable to pollutants. This study analyzed the impact of various concentrations (0, 0.1, 1, and 10 mg/L) of polystyrene MPs (PS MPs) on the immune response of blood clam hemocytes, focusing on the mechanisms of immunotoxicity, including changes in hemoglobin content, reactive oxygen species levels, cell viability, and the expression of immune-related genes. The findings indicate that a one-week exposure to PS MPs significantly compromised the immune response of blood clam hemocytes, exhibiting a pronounced dose-dependent relationship. There was a significant reduction in the total hemocyte count, concentration of hemoglobin, lysozyme content, and activity following PS MPs exposure. Additionally, the levels of calcium ions, the activities of acid and alkaline phosphatases varied with the concentration of PS MPs, suggesting that increased PS MPs concentrations suppress the immune activity of blood clams. This suppression could diminish their capacity to fend off external aggressions and heighten the risk of disease outbreaks. The study provides novel insights into the impact of PS MPs on the immune response of marine bivalves and lays the groundwork for further ecotoxicological research.