Level of Heavy Metals in Freshwater Crab (Cardisoma guahumi) Obtained from Ahmadu Bello University Reservoir, Zaria Nigeria

The levels of Calcium (Ca), Potassium (K), Manganese (Mn), Iron (Fe), Lead (Pb), Zinc (Zn), Bromine (Br), Arsenic (As), Rubidium (Rb), Strontium (Sr), Vanadium (V), Niobium (Nb) and Zirconium (Zr) in crabs Cardisoma guahumi has been evaluated. The crabs were collected in the Ahmadu Bello University Reservoir and analysed for the above metals using Energy Dispersive X-Ray Fluorescence (EDXRF) Technique. The data indicated variable levels of some of the metals in the crab samples. Enrichments of some of the metals were higher than others, in some stations and on the different body components. The most concentrated was calcium (46500±16300ppm) while the least concentration was obtained in Niobium (29.3ppm). Correlation coefficient between the various stations and between the various body components shows significant differences (P <0.05). Concentrations of some metals in Ahmadu Bello University Reservoir, Zaria were found to be higher than the WHO recommended safe reference values. The high level of some of the metals in the crab C. guahumi suggested that the crab can be used as bio-indicator.