Heavy-metals accumulation in five demersal marine species from Nigerian coastal waters (Eastern Central Atlantic, FAO Area 34)

Abstract

The study was conducted on heavy-metals accumulation in five demersal marine species from the Nigerian coastal water (FAO, Area 34) to ascertain the bio-integrity and safety of the Sea foods for export. Five hundred and six (506) specimens (Parapenaeopsis atlantica, Penaeus monodon, Penaeus notialis, Portunus validus and Cynoglossus browni). were sampled from 32 fishing trawlers owned by a reputable private company and assessed fresh for biological (morphometric data) and heavy metals analysis (In-vivo) using 210 Atomic Absorption Spectrophotometer (AAS). Study revealed the Mean weight (Mean±SD) of P. atlantica, P. monodon, P. notialis, P. validus and C. browni were: 9.42 ±0.26, 96.79 ± 2.38, 26.82 ± 1.34, 284.09 ± 7.34 and 411.09 ± 15.27g respectively. Heavy-metal accumulated in the muscles (mg/kg) showed Lead (Pb): 0.15 ± 0.05 for P. atlantica; 0.12 ± 0.06 for P. monodon; 0.15 ± 0.02 for P. notialis; 0.14 ± 0.07 for C. browni; and 0.14 ± 0.08 for P. validus. Iron (Fe) revealed: 2.7 ±0.07, 2.26 ± 0.06, 2.32 ± 0.08, 2.43 ± 0.12, and 2.42 ± 0.09 respectively. Zinc (Zn) also showed: 8.68 ± 0.12, 8.97 ± 0.14, 9.13 ± 0.12, 8.99 ± 0.11 and 8.86 ± 0.08 respectively. Zn and Fe value for P. atlantica were above acceptable limit by FAO/WHO standard. The decreasing order of mean concentrations was Zn>Fe>Pb. Arsenic (As) and Cadmium (Cd) had values of <0.01 for all the species. This report concludes that Mercury (Hg) was not detected throughout the study for all the species. But the detection of lead, iron and zinc in the muscles of species under study cast grey light on the integrity and safety of the fish species and thus relevant agencies are required to respond to reduce this trend for the safety of humans.