Distribution and concentration of trace metals in tissues of pelagic and demersal fishes from the coastal waters of cochin

Abstract

Accumulation of trace metals in the tissues (muscle, gill and liver) of pelagic fishes (Sardinella longiceps, Rastrelliger kanagurta, and Lates calcarifer) and demersal fishes (Cyanoglossus macrostomus, Caranx melampygus, and Nemipterus japonicus) of the coastal waters of Cochin were quantified during the monsoon, post-monsoon and pre-monsoon seasons. The seasonal ranges of metal concentrations in the muscle, gill and liver of fishes were as follows: Fe (445.15 to 817.85 µg/g, 503.85 to 940.56 µg/g, and 578.75 to 1144.85 µg/g); Co (6.18 to 17.18 µg/g, 7.46 to 24.28 µg/g, and 10.65 to 41.65 µg/g); Ni (8.66 to 18.25 µg/g, 12.56 to 41.17 µg/g, and 21.75 to 106.46 µg/g); Cu (2.75 to 5.38 µg/g, 9.06 to 29.05 µg/g, and 17.57 to 43.27 µg/g); Zn (38.35 to 99.25 µg/g, 65.96 to 197.95 µg/g, and 100.48 to 431.67 µg/g); Cd (1.45 to 7.56 µg/g, 1.96 to 13.37 µg/g, and 2.45 to 23.36 µg/g); and Pb (1.57 to 4.88 µg/g, 1.75 to 8.67 µg/g, and 2.48 to 12.85 µg/g). Distinctive species-specific and organ-specific bio-accumulation patterns of trace metals loads were apparent for both the pelagic and demersal fishes for the region. A comparison of trace metal levels in fish organs revealed that the liver appears to be the main target tissue for trace metal storage than gill, while the muscle had the lowest levels of metals. The elevated accumulation of metals in fish tissues is most likely related to the high influx of metals in the Cochin coast due to pollution from anthropogenic wastes on land that were discharged through rivers. Bio-accumulation data on trace metals in fish organs may be helpful in forensic investigations for tracing contaminant sources and their dispersal pathways in oceanic environments.