Trace metals in fish and polluted areas in the Ghanaian continental shelf crustaceans - identifying heavier

Abstract

The concentrations of four trace metals, namely copper, lead, cadmium and manganese, were determined in six fish species and three crustaceans collected from five sites spanning over 70% of the Ghanaian coastline. Copper and lead were determined in Barracuda (Spraena spraena), the Ribbon fish (Trichiurus lepturus), the Sardine (Surdinella spp), the Sole (Cynofossus senegalensis), the Sea Bream (Pagrus coupei ) and the Soldier fish (Cynapastas marmuratus). Cadmium and manganese were analyzed in the Blue Crab (Callinecfes sepidus), the Spiny lobster (Panilirus regius) and the edible shrimp (Crag0 septempinasus). Sampling sites included Takoradi, Elmina, Cape Coast, Accra and Tema. Lead and copper in the fishes ranged 0.25-0.94pgg-' fresh weight and 0.40-2.54 pg g-' dry weight (FW) respectively whilst cadmium and manganese in the crustaceans ranged 0.05-0.083 pgg-' FW and 0.554- 1.404pgg-' FW respectively. The Barracuda accumulated the greatest amount of metals whilst the sardine accumulated the least. With the crustaceans, there was a significant difference between the amounts of the metals accumulated. The blue crab accumulated the greatest and the edible shrimp the least. The analysis showed that: (i) there was a positive correlation between the metals bioconcentrated and the extent of pollution of the marine waters and (ii) along the Ghanaian Continental Shelf, the extent of pollution was of the increasing order as: Elmina = Cape Coast < Takoradi < Accra < Tema. Pollution of the marine waters could be minimized by control of flow of pollutants from land based activities