Shell Organic Matrix (Conchix) of the Mediterranean Mussel Mytilus galloprovincialis L. as the Medium for Assessment of Trace Metals in the Boka Kotorska Bay

Abstract

The content of trace metals, namely Zn, Cu, Fe, Mn, Pb, Cd, and Hg, in four types of media, i.e., soft tissues, shells, and the products of shell demineralization (organic matrix—conchix and extract) of the Mediterranean mussel Mytilus galloprovicialis L., at three sites in the Boka Kotorska Bay of the Adriatic Sea were determined. The main aim was to investigate the accumulation patterns of trace metals in conchix and their possible relationship with other tested media. Conchix weight within a group of mussels from Sv. Nedjelja was significantly higher in comparison with the IMB, while conchix % in the shell showed a negative correlation with dry shell weight. The highest metal pollution index (MPI) values found in the soft tissues of mussels from Sv. Nedjelja, Cogi, and the IMB were 2.319, 2.711, and 2.929 µg g−1, respectively. PCA analysis showed similarities in trace metal accumulation in all media except conchix. According to CCA analysis, conchixes were grouped around Cu, Fe, and Hg, while Cd and Zn were in correlation with the soft tissues. Moreover, the shells were in correlation with Mn. Simple isolation with high yield, close contact to the environment in comparison with calcified shell layers, and susceptibility to possible pollution sources due to the accumulation of specific metals are the main reasons to consider conchix of M. galloprovincialis as a medium with potential in trace metal assessments of marine ecosystems.