ASSESSMENT OF THE PRESENCE OF HEAVY METALS ON VARIOUS ORGANS OF Oreochromis niloticus (FISH) IN OLOGBO RIVER, EDO STATE

Abstract

A comparative study to determine the bio-accumulation, of heavy metals in different
organs of fish (Oreochromis niloticus) in Ologbo River was conducted. The study
which spanned a period of three months from June to August, 2011 investigated
concentrations of heavy metals including Iron, Zinc, Copper, Manganese and
Chromium (Fe, Zn, Cu, Mn and Cr) using the Atomic Absorption Spectrophotometer.
The selected organs for the investigation were muscle tissues, gills and gut. The
mean concentration of the studied heavy metals in the muscle tissue, gills and gut,
were; Iron (7.22±0.19mg/g, 11.77±0.64mg/g and 14.60±0.78mg/g), Manganese
(3.76±0.17mg/g, 8.36±0.29mg/g and 8.23±0.02mg/g), Zinc (2.66±0.16mg/g,
5.66±0.16mg/g and 8.37±0.09mg/g) and Copper (7.21±0.26mg/g, 8.64±0.17mg/g
and 10.74±0.10mg/g) respectively. Chromium was not detected. Gut contained the
highest levels of heavy metals in all the organs of Oreochromis niloticus. Analysis of
variance (ANOVA) revealed high significant difference (P<0.01) between the means
of the heavy metals in the fish organs studied and the actual recommended limit
specified by the World Health Organization (WHO)