Investigation of Selected Trace and Heavy Metals in Two Tropical Fish Species from the Coastal Waters of Ghana

Abstract

Cadmium (Cd), copper, (Cu), Iron (Fe), lead (Pb), and zinc (Zn) burdens were determined by atomic absorption spectrophotometry (AAS) in two tropical fish species (Chloroscombrus chrysurus and Sardinella maderensis) from the western coast of Ghana. Fish samples were collected during three designated Sampling Periods (January 2008 to March 2008 - Periods 1; September 2008 to November 2008 - Period 2; and February 2009 to March 2009 - Period 3) at three sites (Half-Assini, Aboadze and Elmina). Trace elements and heavy metal concentrations in both species followed the order Fe>Zn>Cu while Cd and Pb were below detection limits. High levels of Fe were detected in the fish samples with concentration ranges of 13.05-376.4 μg/g dw. Levels of Cu generally recorded during Period 1 were above FAO maximum recommended limits of 30 μg/g in fish while Zn burdens were below FAO recommended limit of 40 μg/g. S. maderensis and C. chrysurus, can be considered safe for human consumption with respect to Cd, Pb and Zn contaminations. However, Cu will require further monitoring to protect public health. Hazard quotients and hazard indices computed indicate that metal exposure from consumption of the two fish species will not result in any appreciable health risk. Levels of Cu and Zn recorded may however pose threats to physiological functioning of fish since levels were high enough to cause sublethal effects to fish. Metal burdens studied provide background information prior to the commercial exploitation of oil in Ghana’s marine waters.