Bio-transfer factors and temporal variation of heavy metals in different sexes of three species of edible brackish water fish.

This article discusses bioaccumulation and temporal variation of heavy metals in three edible lagoon fish species with references to gender. Cd and As were undetected in the three fish species (i.e., below the method detection limits of 1 μg Cd/kg wet weight and 2 μg As/kg wet weight) irrespective of the periods, and Cd was undetected in the water too (i.e., below the detection limit of 0.0003 mg/L). Except for Zn (which was mainly available as Zn2+ in the water), Pb was present largely as low labile metal-chloride complexes and As as HAsO42- as per Visual MINTEQ, version 3.1. Bio-transfer factors of Sn (which was also undetected in the water; below the detection limit of 0.05 mg/L), Hg, Pb, and Zn were <1 in both sexes, justifying that bioaccumulation was largely attributed to food rather than uptake from the water. Metal accumulation patterns differed drastically between the fish species. Arius maculatus (a carnivore) exhibited higher Zn, Hg, and Sn accumulations during the drier periods (June-September) compared with Mugil cephalus (a detritivore/herbivore) and Etroplus suratensis (an omnivore). Pb was detected only in A. maculatus (July-August) possibly due to biomagnification. Zn was present in higher levels in all species (irrespective of sex) compared with the other metals, but levels were below admissible limits. However, the relationship between temporal variation of Zn and gender in all species was insignificant. In M. cephalus, the temporal variation of Sn and Hg between the sexes was also insignificant. Female A. maculatus and E. suratensis showed higher Hg concentrations, while males showed higher Sn concentrations. Temporal variation patterns of Pb were unclear.