Seasonal variation of heavy metal in seawater, sediment and hooded oyster, Saccostreacucullata, in Iranian southern waters (Chabahar coast)

Seasonal variation of different heavy metal concentrations; iron (Fe), copper (Cu), cadmium (Cd), lead (Pb), zinc (Zn), chromium (Cr), manganese (Mn), and nickel (Ni) were determined in water, sediment, and Oyster tissue of Saccostreacucullata from three stations along Chabahar coast, north coast of Oman Sea. The concentration order of heavy metals was as follows: Fe Cr Zn Ni Mn Cu Pb Cd (seawater), Zn Cu Mn Ni Cr Pb Fe Cd (sediment) and Zn Cu Mn Ni Cr Pb Fe Cd (Oyster tissue). There was significant difference (p 0.05) in metals levels between different seasons and stations. Generally, the highest values of heavy metals were detected during summer and the lowest values during winter. The highest concentrations of heavy metal in seawater, sediment and oyster tissue were recorded at site II where is near the harbour and industrial activities. The highest concentration of Mn, Fe, Cr, Cd, and Pb was detected in sediment and the highest concentration of Ni, Zn and Cu was identified in Oyster tissue. This study showed that there was a positive significant correlation between accumulation of metals in oysters, seawater, and sediment. The results showed that the sediment is a suitable indicator of heavy metal pollution, because it can work as a hunter agent for heavy metals and an adsorptive sink in aquatic environments. Furthermore, oysters accumulate certain heavy metals in their tissue and can be considered as a bio-indicator to determine heavy metals pollution on ecosystems.