This study investigated bioaccumulation of heavy metals and cytogenotoxic
effects that could result from exposure of fish to heavy metals in the Asa River, Ilorin, Nigeria.
The three different fish species,
Tilapia zilli
,
Oreochromis niloticus
and
Sarotherodon galilaeus
were obtained from the Asa River and the fourth species,
Clarias gariepinus
was cultured in the
laboratory to serve as control. The fish organs; bone, gills, kidney and liver from the four fish
species were carefully dissected for the determination of some heavy metals. The results showed
that the metal concentration levels were in the order Pb> Cr > Zn > Cd. The highest lead
concentration value was observed in the gills of
Tilapia
fish. The lowest level of Cd was
observed in the bone tissue of
Oreochromis niloticus. The values of heavy metals found in the
cultured fish species were very low in concentration compared to the ones sourced from Asa
River. Micronuclei and frequencies of nuclear abnormalities were assessed in the blood
erythrocytes of both laboratory cultured fish and the ones obtained from Asa River. Significant
differences (P<0.05) were observed for mean frequencies of micronucleus induction in the blood
erythrocytes of
Oreochromis niloticus,
Sarotherodon galilaeus. As for other nuclear
abnormalities, significant differences (P<0.05) were observed for mean frequencies in the blood
erythrocytes, gills and liver of
Tilapia zilli and
Oreochromis niloticus. Genotoxicity results in
this study showed that the Asa river water contains genotoxic metals say be responsible for the
micronucleus and nuclear abnormalities observed in the aquatic environment. ©JASEM
