Comparative Study of Persistent Toxic Metal Levels in Land Crab (Cardiosoma armatum) and Lagoon Crab (Callinectes amnicola) in Lagos Lagoon
Journal of Marine Biology & Oceanography
The comparative study of persistent toxic metal levels of two species of crab Cardiosoma armatum and Callinectes amnicola were studied from June 2009 to October 2009. This work provided information on the concentration of Cd, Zn, Ni, Fe and Pb in the limb, shell, flesh and gills of the two species of crab, so also their environment-water and sediments. This analysis will help in assessing accumulation of metals in these organisms. Metal concentration was determined using wet digestion and
... digestion and analyzed using Atomic Absorption Spectrophotometer (AAS). The concentrations of metals observed in the crab samples were lower than the WHO permissible level of 2.00 µg/g for Lead (Pb) and Cadmium (Cd) in foods. The mean values obtained ranged in Fe (0.041-0.219 µg/g); Zn (0.647-1.774 µg/g); Cd (0.093-0.635 µg/g); Ni (0.261-0.825 µg/g); Pb (0.160-0.261 µg/g) for Callinectes amnicola and Fe (0.071-0.313 µg/g); Zn (0.807-1.731 µg/g); Cd (0.022-0.663 µg/g); Ni (0.181-1.279 µg/g); Pb (0.151-0.501 µg/g) for Cardiosoma armatum. Although, the levels were lower than the permissible levels, it was observed that Cardiosoma armatum and Callinectes amnicola had higher level of metals than their immediate environment. This is an indication of bioaccumulation of the persistent toxic metals in the organisms. However, there was no significant difference in the distribution of metals between the two crabs at 95% confidence level.