Assessment of Toxic Metals Concentration using Pearl Oyster, ‎Pinctada radiate, as Bioindicator on the Coast of Persian Gulf, Iran‎

Background: Persian Gulf is a semi-closed environment which is affected by pollution ‎from heavy metals. Entrance of heavy metals to the water column and binding to ‎sediment particles can affect the benthic organisms that can accumulate these ‎materials in their body. Noticing this ability, mussels are considered as bio-monitoring ‎agents.‎ Methods: The pearl oyster, Pinctada radiate, and sediment samples were collected ‎from Lengeh Port and Qeshm Island. For measuring heavy metals, 0.5g of soft tissue ‎and 1g of shell and sediment were digested by HNO3 (69%) and hot block digester. The ‎prepared samples were evaluated for Cd, Cu, and Zn using a flame AAS Model 67OG ‎while for Pb a graphite furnace AAS was used.‎ Results: Higher metal accumulations were observed in soft tissues. Positive ‎correlations between Cd, Pb, Zn, and Cu concentrations in sediments and soft tissues ‎of oyster were observed. The use of soft tissue of P. radiata as an indicator showed the ‎highest accumulations of Cd (9.76±0.59) and Zn (3142.60±477.10) in Lengeh Port, but ‎there were no significant differences in Cu and Pb concentrations between the two ‎stations.‎ Conclusion: The higher concentrations of heavy metals in P. radiata’ soft tissue in ‎comparison to shell suggested this material as a better heavy metals indicator than ‎shell. Also, the correlation between heavy metals concentration in soft tissue and ‎sediment improve this idea that soft tissue of Pinctada radiata can be considered as a ‎biomonitoring agent for toxic metals pollutions. Hence, using this bioindicator showed ‎Lengeh Port as more polluted station than Qeshm Island.‎