Long-term Monitoring of Pollution of the Coastal Water Area of Ussuriysk Bay with Metals: Case Study of “Green” Oysters Magallana gigas (= Crassostrea gigas) (Thunberg, 1793)

In September 2021, the content of heavy metals Pb, Cu, Cd, Zn, Ni, Fe, and Mn was estimated in the tissues of the oyster Magallana gigas (= Crassostrea gigas) (Thunberg, 1793) and in the silty fraction of bottom sediments from mollusk habitats in coastal waters around the Muravyov-Amursky Peninsula, including the most polluted area off the western coast of Ussuri Bay of the Sea of Japan. It has been shown that, despite the reclamation of the landfill located here in 2010, being the main source of metal pollution, copper is present in high concentrations in bottom sediments and tissues of oysters, giving them a green color. The mollusks living in this area also retain a high concentration of zinc. The concentrations of Pb, Cd, and Ni in oyster tissues over the past 20 years have decreased by 2–5 times in accordance with the decrease in the number of mobile forms of these metals in bottom sediments; however, they are still 3–6 times higher than regional estimates for polluted water areas. With abnormal accumulation of copper, manganese, on the contrary, demonstrates a decrease in the concentration in the tissues of oysters from the most polluted stations, reflecting the deterioration of the physiological state of mollusks. The results obtained indicate the need to continue the remediation of the western coast of Ussuri Bay and monitor the pollution of coastal waters with metals.