Bioaccumulation of heavy metals in commercial fishes from Adyar estuary (Mugil cephalus and Megalops cyprinoides)

The Adyar Estuary in Chennai, India, is facing pollution from urban sewage and industrial effluents. This study aimed to investigate heavy metal bioaccumulation in brackish water fishes, Mugil cephalus and Megalops cyprinoides, as well as heavy metal concentrations in water samples from the Adyar River. The objective was to assess the risks associated with heavy metal accumulation in the edible parts of these fishes and evaluate their suitability for human consumption. The heavy metal concentrations in water samples from the Adyar River were found in the following order: Zn > Fe > Cu > Cd > Cr. In M. cephalus, the heavy metal accumulation detection in muscles shows Fe being the most accumulated metal and Cd being the least accumulated in the muscles in the following order; (0.29 mu g/g), >Cu (0.09 mu g/g), > Cr (0.08 mu g/g), > Cd (0.01 mu g/g). similarly, In M. cyprinoides, heavy metal accumulation in the muscles is observed in the following order: Cu (0.40 mu g/g) > Fe (0.21 mu g/g) > Zn (0.08 mu g/g) > Cr (0.01 mu g/g). In M. cephalus, the brain and heart showed the highest metal concentrations compared to the liver and gills. Conversely, the muscle tended to accumulate lower levels of metals. In M. cyprinoides, heavy metal accumulation is highest in the heart, followed by the brain. Alternatively, the muscle tended to have lower levels of metal accumulation. Despite metal concentrations surpassing recommended limits, the edible fish parts remain safe for human consumption, indicating no significant threat to public health. Continuous monitoring of heavy metal levels in both water and fish samples over time is crucial to ensure sustained safety for human consumption, with future studies potentially focusing on specific pathways of heavy metal uptake by fish and their potential long-term effects on human health.