Rahila Banu S., Lavanya R., S. Kaneez Fathima, S.B. Yasmeen and Kaviyanjali M.
Abstract
This study examined microplastic accumulation and oxidative stress in three commercial marine fish: oil sardine (Sardinella longiceps), anchovy (Stolephorus indicus), and red snapper (Lutjanus malabaricus) from Chennai. Tissues (gill, gut and muscle; 2 grams each) were digested with potassium hydroxide, density separation was done using saturated sodium chloride, filtered, and analysed with a stereomicroscope. Microplastics ranged between 100 and 500 micrometres, mainly fibers and fragments in blue, black, pink, red, violet, green, and brown colours. Fourier transform infrared spectroscopy (FTIR) identified nylon, polystyrene, polycarbonate, polypropylene, polyvinyl chloride, polyethylene terephthalate, polymethyl methacrylate, and polytetrafluoroethylene. Oxidative stress markers were measured: malondialdehyde (lipid peroxidation at 532 nanometers), peroxidase (470 nanometers), and catalase (240 nanometers). Red snapper (Lutjanus malabaricus) showed highest malondialdehyde, followed by anchovy (Stolephorus indicus) and oil sardine (Sardinella longiceps). Catalase activity was high in oil sardine (Sardinella longiceps) compared with red snapper (Lutjanus malabaricus). One-way ANOVA analysis of variance indicated high significant species effect on malondialdehyde (F (2,6) = 257.01, P < 0.001) meanwhile peroxidase (F (2,6) = 15.83, P < 0.01) showed a significant effect and catalase (F (2,6) = 60.78, P < 0.001). Microplastics induce species-specific lipid peroxidation with distinct enzymatic antioxidant responses, posing risks to fish health and seafood safety. Enhanced monitoring is needed.