Distribution and relationships of selected trace metals in molluscs and associated sediments from the Gulf of Aden, Yemen

Concentrations of Cd, Pb, Zn, Cu, Ni, Co, Cr, Mn and Fe in the soft tissue of Turbo coronatus, Acanthopleura haddoni, Ostrea cucullata and Pitar sp., as well as in associated surface sediments (bulk and bioavailable metal con centrations) from the Gulf of Aden, Yemen, were determined by atomic absorp tion spectrophotometry method. Large differences between size-classes of mo lluscs in metal concentrations were recorded. Significant spatial differenc es in metal concentrations in both the soft tissue of the molluscs and asso ciated sediments studied were mostly identified. Statistically significant correlations (p<0.01) between concentrations of selected metals were observ ed. A slope of the linear regression is significantly higher than unity for Fe (9.91) and Cd (3.45) in A. haddoni and for Ni (4.15) in T. coronatus, s uggesting that the bioavailability of these metals is disproportionally inc reased with a degree of enrichment of the sediments in Fe, Cd and Ni, respe ctively. A slope constant approximating to unity (1.14) for Cu in A. haddon i relative to its concentration in sediment extract implies that bioavailab ility of this metal proportionally increased with growing concentrations of its labile forms in the associated sediment. The degree of contamination o f Gulf of Aden waters by the metals studied is discussed and the potential ability of molluscs, especially A. haddoni and T. coronatus, as biomonitors of metallic pollutants is postulated. (C) 1999 Elsevier Science Ltd. All r ights reserved.