COMPARATIVE BIOACCUMULATION OF SOME HEAVY METALS IN TISSUES OF THREE SELECTED FISH SPECIES FROM AKPA YAFE RIVER, IKANG, CROSS RIVER STATE, NIGERIA

This study was carried out to provide information on comparative bioaccumulation of some heavy metals in tissues of three selected fish species from Akpa Yafe River and to evaluate the possible risks associated with consumption of fish with high level of metals. Consumable sizes of fresh fish species: Sphyraena barracuda, Chrysichthys nigrodigitatus and Mugil cephalus were sampled once a month for a period of three months at the landing site (Ikang Beach) of Akpa Yafe River and were transported immediately in ice pack container to the laboratory for analysis. Digested samples were analysed to determine the concentrations of Cd, Cu, Fe, Ni and Zn in the fish tissues using Atomic Absorption Spectrophotometer (AAS). The concentration levels of some of the metals in the fish tissues were higher than the maximum permissible limit. The fish species have accumulated to different degrees, the analyzed heavy metals in their tissues, indicating that the environment is impacted. The bioaccumulation factor reveals that the tissues of C. nigrodigitatus have been polluted by Cu and contaminated by Cd, Fe, Ni and Zn while the tissues of M. cephalus have been polluted by Cu and Ni and contaminated by Cd, Fe and Zn. The tissues of S. barracuda have been polluted by Ni and contaminated by Cd, Cu, Fe and Zn. Heavy consumption of fish by humans in the locality, as is the current situation, is therefore unadvisable because of its negative health implication. The heavy metals load in the river may be as a result of domestic sewage, industrial effluent and metal leachates from garbage and solid waters dumps. Bioaccumulation of heavy metals by aquatic life is dangerous since these heavy metals could be transferred to humans through food chain. Through biological amplification, some aquatic organisms may build up concentration of metals present in low concentration in the aquatic environment to levels which are harmful to life and exceed public health standards. Therefore activities resulting to input of heavy metals into Akpa Yafe River should be avoided.