Density and intensity of metallothionein of Crassostrea sp. as biomarkers of heavy metal contamination in the Northern coast of East Java, Indonesia

The present study aimed to observe the expression level of metallothionein by analyzing its density and intensity in the gill and stomach of Crassostrea glomerata and Crassostrea iredalei. The mussels were collected from three sampling locations in the Northern coast of East Java, Indonesia: Mayangan, Probolinggo (Station 1), Kenjeran beach, Surabaya (Station 2), and Gresik Ports (Station 3). The density and intensity of metallothionein were analyzed by using immunohistochemistry technique. The results showed that the highest density of metallothionein in Crassostrea iredalei was at Station 3 (Gresik) i.e. 47.8 × 10−3 (MT/µm2) in gill and 42.2 × 10−3 (MT/µm2) in stomach. While, the highest density value in Crassostrea glomerata was observed at Station 3 (Gresik) i.e. 64 × 10−3 (MT/µm2) in gill and 45.6 × 10−3 (MT/µm2) in stomach. Furthermore, the correlation analysis of heavy metals concentration with the density and intensity of metallothionein showed a significant correlation. This result indicates that the concentrations of the investigated heavy metals (i.e. Pb, Cd and Hg) in seawater correlated with the density and intensity of metallothionein in the gill and stomach of mussels (Crassostrea glomerata and Crassostrea iredalei), which can be used as biomarkers of heavy metal contamination.