Evaluation of crab Callinectes amnicola contamination by heavy metals (Pb, Cd, Cu, Zn, Fe, Cr, Ni, As) in the complex Nokoué lake Porto-novo lagoon in South Benin

Abstract

The surface water and aquatic species contamination by metallic trace elements has become a major concern. The present study aims to determine the contamination levels of metallic trace elements of crab Callinectes amnicola caught in the Ganvié, Zogbo and Hwlacomey stations in the complex Nokoué lake Porto Novo lagoon in South Benin. For this, eight metallic trace elements (Pb, Cd, Cu, Zn, Fe, Cr, Ni, As) were analyzed in water, entire crabs and organs using a flame atomic absorption spectrophotometer. Water from Hwlacomey station has significantly recorded the highest concentrations in chrome and arsenic while those of the Zogbo station recorded the highest concentration of iron. Cd and As concentrations were significantly higher in Ganvié samples whereas Cu, Zn, Cr and Ni concentrations were higher in Zogbo samples. The crabs collected in Hwlacomey have meanwhile recorded the highest contents in Pb and Fe. As for the organs, they were also contaminated by the metallic trace elements and the concentrations also varied significantly (p <0.05) between these organs. Gills, ovaries and muscles have significantly recorded the highest copper and zinc contents while the carapace has recorded the highest lead and chromium contents. The claws and the testicles had the highest concentrations of arsenic. In the complex Nokoué lake Porto-Novo lagoon, Callinectes amnicola is contaminated by toxic metals at higher concentrations than the standards reference.