Macro and Trace Element Accumulation in Edible Crabs and Frogs in Alaro Stream Ecosystem, Ibadan

The tissue accumulation of five macroelements (Na, Mg, K, Ca, Fe) and twelve trace elements (Vd, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, Pb) were assessed in the organs of the edible frogs; Xenopus laevis and Rana esculentus, and whole body of the crab, Callinestes caught from Alaro Stream Floodplain (Ibadan, Nigeria).The liver of the edible frogs showed higher concentrations of Cu, Mo, and Cd, while Na, Mg, K, V, Mn, Fe, Co, Zn and Pb were higher than the other organs in Rana esculentus. In the liver of Xenopus laevis, Se and Ag were higher than the bone, gut, heart and muscle while Ag was the only trace element with the lowest concentration in the bones of the edible frog in contrast to Ca which ranked highest in the study. Ag was the least accumulated in the whole body of the crab, Callinestes while Ca was the highest mean level of 139364ppm in the study. Significant correlation was recorded between the bioaccumulated macro and trace elements in the crabs and frogs. With the exception of Ag, all the other trace elements exceeded the guidelines and standards given by the Federal Environmental Protection Agency of Nigeria. Public health consciousness and regular monitoring is therefore necessary in the consumption of these aquatic food resources. Macro and trace element accumulation in edible frogs and crabs in a contaminated watershed in the tropical region.Keywords: macro element, trace element, edible frogs, crab

Toxicology of arsenic in fish and aquatic systems

Abstract: Arsenic (As) is found in waters such as seawater, warm springs, groundwater, rivers, and lakes. In aquatic environments, As occurs as a mixture of arsenate and arsenite, with arsenate usually predominating. The unrestricted application of As pesticides, industrial activities, and mining operations has led to the global occurrence of soluble As above permissible levels of 0.010 mg/L. Continuous exposure of freshwater organisms including fish to low concentrations of As results in bioaccumulation, notably in liver and kidney. As a consequence As induces hyperglycemia, depletion of enzymatic activities, various acute and chronic toxicity, and immune system dysfunction. Here we review arsenic chemistry, the occurrence of arsenic in aquatic system, the transformation and metabolism of arsenic; arsenic bioaccumulation and bioconcentration; behavioral changes; and acute and other effects such as biochemical, immunotoxic, and cytogenotoxic effects on fish