Distribution and association of trace metals in soft tissue and byssus of mollusc Perna perna from the Gulf of Aden, Yemen

Abstract

Concentrations of Cd, Pb, Zn, Cu, Mn, and Fe in soft tissue and byssal threads of Perna perna from the Gulf of Aden, Yemen, were determined by atomic absorption spectrophotometric (AAS) method. Significant inter-regional differences in the metal concentrations studied in both soft tissue and byssus were identified. The concentration of Cd was an order of magnitude greater in soft tissue than in byssal threads. Statistically significant correlations ( p<0.01, p<0.05) between concentrations of selected metals were observed. The spatial distribution of Cu in byssal threads was similar to that in soft tissue. The data indicate that sewage input (at Sira Island) is the most likely anthropogenic source of Cu and Mn. The concentration of tissue Cd at the Fuqum area was the highest among the other stations. Although the Fuqum area is off the harbour, water from a fishery refrigerator and some sewage outflow flux into the sea. It is assumed that the presence of the area near the strait of Bab Al-Mandab, where the water coming from both the Red Sea and the Indian Ocean mixes, especially during the seasonal monsoons, is responsible mainly for elevated tissue Cd concentrations in the molluscs.