Seasonal variations of trace metal concentrations (Hg, Cd, Pb, Cr, Zn, and Cu) were investigated in the hepatopancreas and soft tissues (remaining parts of bivalves such as gill, mantle, foot, and muscle) of Tapes decussatus and Mytilus galloprovincialis from the Homa Lagoon. The highest metal concentrations were recorded frequently in February and July in M. galloprovincialis and T. decussatus, respectively. Trace metal levels (except Zn) in the hepatopancreas were higher than those in soft tissue for both bivalves. The results showed that the mean concentrations of Hg, Cd, and Zn for M. galloprovincialis were higher compared to T. decussatus in both tissues. The metal concentrations in both bivalves from the Homa Lagoon were generally below the values of provisional tolerable weekly intake (PTWI) estimates, in terms of human health risk. According to hazard quotient (HQ), Cr values for both species and Cd values for only M. galloprovincialis were found greater than one. Also, total hazard index (THI) values were greater than one in both bivalves, having a potential risk for consumers.

Antioxidant related biomarkers (superoxide dismutase, catalase, malondialdehyde) were investigated to evaluate metal (Hg, Cd, Pb, Cr, Cu, Zn, and Mn) bioaccumulation in some organs of fish species (Sparus aurata, Chelon labrosus, Diplodus vulgaris) from the İzmir Bay. Samples were collected at November 2019 from Inner and Outer Bays. Metal and biomarker analyses were carried out by Atomic Absorption Spectrometer and microplate reader, respectively. For metal analyses in organs, higher metal bioaccumulations were found at liver tissues. Higher Hg and Zn concentrations were found in S. aurata, higher Cd, Cr, Cu and, Mn concentrations were detected in C. labrosus and higher Pb concentrations were determined in D. vulgaris. In biomarker results, superoxide dismutase (SOD) and catalase (CAT) activities were generally higher in gills, however, MDA contents were higher at liver. The highest biomarker results were detected at C. labrosus. Statistical analyses were demonstrated that especially MDA content were expressed strong responses for the metal bioaccumulations. Also, Mn levels were considerably correlated with all biomarkers as expected. This study revealed that combined utilization of biomarkers and metal concentrations could be a vital indicator to investigate health status of the marine ecosystems.