Oxidative stress and histopathological effects by microplastic beads, in the crayfish Procambarus clarkii, and fiddler crab Leptuca pugilator

The present study was aimed at evaluating the in vivo effects of microplastics (MP), in terms of oxidative stress and histopathological effects, in two crustacean species: Procambarus clarkii and Leptuca pugilator. In addition, MP accumulation in the hepatopancreas (HP) of both species was also determined. Adults of both crayfish and crabs were exposed for one month to fluorescent polystyrene beads (size: 1 μm) at nominal concentrations of 1000 or 5000 particles/mL. During the exposure, animals were maintained under controlled feeding, aeration, temperature, and photoperiod conditions. At the end of the exposure, HP and hemolymph (HL) samples were harvested for analysis of oxidative damage and total antioxidant levels. Additionally, the presence of MPs in both tissues was confirmed. Significant differences with the control groups were observed in lipid peroxidation levels in HP in animals exposed to the lowest concentration in P. clarkii and to the highest concentration in L. pugilator. A marked increase in antioxidant levels was also observed in the HL at both concentrations in P. clarkii, and at the highest MPs concentration in L. pugilator. Moreover, several histopathological changes were detected in both gills and HP, including hypertrophied lamellae, lifting or collapse of gill epithelia, loss of normal shape of hepatopancreatic tubules, and epithelial atrophy in the HP tissue. We conclude that exposure to MP beads at selected concentrations results in oxidative damage, induces histopathological changes in gills and HP, and triggers an antioxidant response in two crustacean species.