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