Bioaccumulation of heavy metals in the different tissues of Mackerel scad, Decapterus macarellus (Cuvier, 1833) collected from Karachi and Gwadar Coasts of Pakistan

INTRODUCTION: Among other aquatic animals, fish can also accumulate a large number of toxic metals in their various body organs, which may enter in the human body and cause serious health issues. Therefore, the basic aim of this study was to observe the level of some heavy metals (i.e., Pb, Fe, Cu, Cd, Cr) found in the different tissues of Decapterus macarellus collected from the Karachi and Gwadar coasts of Pakistan. METHODS: About 200 fish samples of five different size groups of Decapterus macarellus were collected from Gwadar and Karachi fish harbors during April to September 2020. Total 10 samples of each size group i.e., S1, S2, S3, S4 & S5 were collected from each coast. Heavy metals were analyzed in fish samples by using the atomic absorption spectrophotometer (AAS). RESULTS: The overall results revealed that some metals like Cu, Pb, Cd & Cr contents were high in the stomach, while less in the muscles. Whereas, the concentration of Fe was found to be high in the liver, while low in skin of fish. The average values of bioaccumulation of these heavy metals (BAF) were found in decreasing order of Cu > Cd > Fe > Cr > Pb. In this study, except Cd and Cr, all metals were found within the permissible limits. Both sediment and water from the selected site areas were also analyzed to observe their pollution levels in the order of; sediment > water > fish tissues. CONCLUSION: Thus, it was concluded that the Karachi environment was much more polluted than the Gwadar environment because it is in an industrial unit and a busy sea site for trade. Moreover, consuming muscles from this species is safe for human health except for iron toxicity, but the use of the liver is not beneficial for all selected metals. Thus, the present work will also be helpful to monitor these toxic metals in a food chain and maintain a healthy life, and reduce all kinds of health risks associated with them.