ETHMALOSA FIMBRIATA AND CHRYSICHTHYS MACROPOGON AS BIO-INDICATOR OF HEAVY METALS IN FOUR COASTAL WATERS OF ILAJE LGA,ONDO STATE,NIGERIA

Abstract

Due to oil exploration activities and urbanization as well as continuous industrial and agricultural growth in Ondo State, Nigeria. The coastal water has been heavily impacted by a number of pollutants originating from different anthropogenic activities which resulted in the discharge of heavy metals into the water bodies. This study assessed the accumulation levels of Lead (Pb), Copper (Cu), Iron (Fe), Cadmium (Cd), Zinc (Zn) and Manganese (Mn) in different organs (Gills and Muscle) of two fish species (Ethmalosa fimbriata and Chrysichthys macropogon) and the Length-Weight relationship and condition factor of the two species from four coastal towns (Ayetoro, Bijimi, Idiogba and Asumogha) of Ilaje Local Government Area, Ondo State, Nigeria. Sample collection was carried out monthly for four months in the four stations using gillnet with mesh sizes 0.6cm, 1.0cm, 2.0cm, 3.0cm and 4.0cm throughout the study period. The fishes were grouped into four (4) categories based on their weight which ranges between: 0 – 50g(Group A), 51 – 100g(Group B), 101 – 150g(Group C) and 151 – 200g(Group D). The fish samples were digested after which the heavy metals concentration were analyzed using AA240FS Atomic Absorption Spectrophotometer (AAS). The concentrations of Zn in the fishes were within the FAO guideline of 30mg/kg, the concentrations of Cd in both fish fell below the FEPA concentration of 2.1μg/g while the level of Cu and Zn in the muscle and gill of E. fimbriata were low and below the WHO limits of 0.5 and 2.5 respectively. This findings showed that E. fimbriata and C. macropogon from the study areas bio-accumulated heavy metals, and therefore indicated that the area is polluted. The two sampled species indicated allometric growth patterns (0-3). The low K value obtained (0.60-1.0) may be attributed to pollution status or anthropogenic activities that occur in it while the weight and length exhibited negative correlations with all the heavy metals examined.