Bioaccumulation of Heavy Metals in Three Species of Fresh Water Fish from Weras Ganga: Evidence for Bio Magnification

Abstract

This paper reports the evidence for biomagnification in three species of fresh water fish: Oreochromis mossambicus, Ophiocephalus striatus and Heteropneustesfossilis with different feeding habits, from Weras Ganga in the Colombo District. The muscle, gills, kidney, gonad and Iiver of fish were analyzed by the X-ray fluorescence method and the mean concentrations of heavy metals in each species, were computed in ug/g dry organ weight. It was seen that the piscivore (Ophiocephalus striatus) had much higher levels (aggregated means for all the organs) of Cu (131.6±7.1O), Zn (639.2±12.30), Cr (3.03±1.23), Ni (ll.06±2.35) and Ti (l8.6±2.30) than both the omnivore (Oreochromis mossambicus) and the detritivore (Heteropneustes fossilis}, showing evidence of biomagnification. The concentrations of Fe (l463.4±22.70) and Mn (l83.9±7.07) were highest in Oreochromis mossambicus. Further studies of its feeding habit may provide an explanation for this. The lowest concentration of all metals was recorded in the detritivore.