Assessment of Trace Metal Levels in Fish Species of Lagos Lagoon

Abstract

Fish species, surface water, bottom water, epipellic and benthic sediments were collected from Oworonshoki, Lagos lagoon, to determine their trace metal levels using atomic absorption spectrophotometer. The fish species collected were Tilapia guineensis, Chrysichthys nigrodigitatus, Liza grandisquamis and Psettias sebae. The results indicated that the highest concentrations of trace metals were present in the fish species, followed by benthic sediments, epipellic sediments, bottom water, and surface water. Levels of trace metals found in males and females of fish species showed significant differences. The female species, except Tilapia guineensis, accumulated higher Fe and Zn values. The female species of Psettias sebae was a good bio-indicator of trace metal contamination in the lagoon. Cd and Ni were not detected in any of the fish species. Pb levels in the fishes were above the maximum acceptable limit for human consumption, and could have been sourced from the discharge of industrial wastes into the lagoon. The levels of Fe and Zn in the water, sediment and fishes were all within acceptable limits. The highest condition factor of 2.76 was observed in the female of Chrysichthys nigrodigitatus, while the female, Psettias sebae, had the least condition factor of 0.57, correlating with its high metal contamination.