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.
