Exploring the Coexposure Effects of Pyrogallol and Microplastic on the Red Swamp Crayfish Procambarus clarkii

Abstract

Investigating the impact of two or more toxic chemicals on aquatic organisms is one of the main objectives of toxicological research. Microplastics (MPs) are identified as a carrier or vector for other pollutants. Therefore, the current study investigated the effects of both pyrogallol (PG) and MPs, individually and in combination, on freshwater crayfish (Procambarus clarkii). Following a 15-day exposure to 10 mg/L of PG and100 mg/L MPs and their combination (10 mg/L PG + 100 mg/L MPs), the hemocyte count, hepatopancreatic parameters, antioxidant variables, and histopathological markers were all assessed in the crayfish. The results revealed that PG and MPs potentially individually or combined altered the hemocyte count (including granular and semigranular) compared to control group (0.001 ≥ p < 0.0001). The levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and protein showed significant elevation (p < 0.05) in PG–MP-exposed fish compared to control ones. In comparison to control P. clarkii, the measured oxidation indicators, superoxide dismutase (SOD), glutathione (GSH), and total antioxidant capacity (TAC), showed a significant reduction after single exposure to PG and MPs (0.001 > p < 0.0001), while catalase (CAT) and malondialdehyde (MDA) elevated drastically (0.05 > p < 0.0001). The histology of the hepatopancreas has shown many deformities and abnormalities after individual or combined toxicity, such as vacuolations, degraded hepatopancreatic tubules, eosinophilic deposits, hemocytic infiltrations, and aberrant tubules. Accordingly, there is a synergistic relationship between PG and MP toxicity to crayfish. Therefore, it is crucial to routinely check and assess the discharge of waste into waterways.