BackgroundThe present work was designed to detect heavy metal contents of Al, Zn, Fe, Mn, Ni, V, Co, Cr and Cu in sediments and shells of the Trachycardium lacunosum collected in polluted and unpolluted areas along the Persian Gulf.MethodsThe samples were taken from surface sediments (0-10 cm) and shells of Trachycardium lacunosum in two separated areas (polluted and unpolluted) in northern part of the Persian Gulf, Asaluyeh Bay, during summer 2013. The prepared samples were analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES).ResultsBased on the results, all measured metals including Al, Zn, Fe, Mn, Ni, V, Co, Cr and Cu were meaningfully higher in the sediment samples of polluted area compared to unpolluted area and the order of metal concentrations in the sediment samples were Cr > Co > V > Ni > Zn > Cu > Fe > Al > Mn in polluted area. In the case of shell samples of Trachycardium lacunosum, polluted area contained significantly higher contents of Al, Zn, Fe, Mn, Ni, Co, Cr and Cu compared to unpolluted area and the order of metal concentrations in the shell samples were Fe > Zn > Al > Mn > Cu > Cr > Ni > Co in the polluted area.ConclusionIt was concluded that shells of the Trachycardium lacunosum can be used as a suitable bioindicator for heavy metals in the aquatic environment. Results confirmed that due to the possible contaminations by oil and gas activities near the polluted area perennial monitoring and mitigation measures is extremely necessary.

Warming and acidification are expected impact of climate change that will affect marine areas in the future. These areas are, furthermore, vulnerable to strong anthropogenic stresses such as chemical pollutants. Nevertheless, the consequences of both stressors for marine ecosystems and organisms are still unidentified. The present study aims to examine, for the first time, the effect of temperature and CO2 pressure increase on bioaccumulation of phenanthrene as a PAHs model in four tissues, gills, digestive gland, muscle and mantle of a commercially important pearl oyster Pinctada radiata. Oysters were exposed to various combination of the ambient temperature and pH currently measured in Persian Gulf (T = 24 ºC and pH = 8.1) and the expected ocean warming and acidification (T = 28 ºC and pH = 7.6), as well as proper PhE concentration (0.8 ng.l− 1) during 28 days. In all exposures, higher PhE contents were observed under hypercapnia and warming condition in the digestive gland and gills, followed by the mantle and muscle. Generally, the results visibly reveal that longer exposure period led to promote PhE bioaccumulation in all tissues under ocean warming and acidification environment which was time-dependent pattern of PhE accumulation in P.radiata. Present-day PhE environmental concentrations, which combined with ocean warming and acidification, may lead to rigorous interruption of physiological functions can be extra threatened the ecological fitness of pearl oysters.