An ecophysiological discussion of trace element bioaccumulation in cultured Mytilus galloprovincialis

Monitoring programs conducted by the French Research Institute for the Exploitation of the Sea IFREMER have been using the mussel watch approach introduced by Goldberg [1] since 1974, initially on wild and cultured bivalve mollusks [2], leading to long time data series for several trace elements (TEs: Ag, Cd, Cr, Cu, Hg, Ni, Pb, V and Zn; http://envlit.ifremer.fr/). Since 1996, transplanted caged Mytilus galloprovincialis Lamarck, 1819 have been used to characterize the chemical contamination of Mediterranean coastal waters even in locations where no native wild mussels were available. This project succeeded in assessing the natural background and the extent of the chemical contamination first at the scale of the French Mediterranean littoral [3,4], and more recently at the scale of the whole western Mediterranean Sea [5,6]. However, these programs have focussed on a limited number of metals. Nowadays, the development of very sensitive equipment allows the measurement of some TEs found at very low environmental levels. In parallel, recent technological developments have led to an increase in the extraction and industrial refinement of TEs previously of little concern. Therefore, the environmental monitoring of less studied, potentially toxic TEs of emerging environmental concern is relevant [7]. From data previously published by richir & Gobert [7], the first objective of this short note was to discuss the bioaccumulation profile of 19 TEs that have been either broadly (Cr, Ni, Cu, Zn, Cd, Pb, As, Ag and V) or little monitored (Be, Al, Fe, Mn, Co, Se, Mo, Sn, Sb and Bi) in the Mediterranean mussel M. galloprovincialis. The second objective was to test the relevance of the Trace Element Pollution Index of richir & Gobert [8] when modelling the effect of the shell length and flesh dry weight on the overall accumulation of these 19 TEs in ropegrown mussels. Because of the importance of gametogenesis in the physiological cycle of M. galloprovincialis, the third objective was to briefly discuss the deterministic effect of the sex and the reproductive status on the overall TE bioaccumulation and the TE-specific compartmentalization in that species.