Molecular genetic differentiation of native populations of Mediterranean blue mussels, Mytilus galloprovincialis Lamarck, 1819, and the relationship with environmental variables

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Reproductive cycle and follicle cleaning process of Mytilus galloprovincialis (Mollusca: Bivalvia) from a polluted coastal site in Algeria

This work focused on the reproductive cycle and cleaning process of follicles in Mytilus galloprovincialis and aimed to extend knowledge of the reproductive cycles of Mytilidae. Biometric and histological measurements were taken monthly over 12 months from mussels at a polluted site, the port of Oran in Algeria. Environmental parameters were monitored concomitantly. Mytilus galloprovincialis reproduced throughout the year, with a main spawning period between November and February and a second between March and June. Several follicle cleaning processes were observed throughout the reproductive cycle. They occurred under two circumstances. First, in the absence of reserve tissues, mature gametes were degraded. This happened when spawning was about to end and corresponded to the last stage of reproduction. Second, atresia, gamete degeneration and a cessation of spawning occurred whatever the stage of the gonad development and whatever the environmental parameter values. These disturbances of reproduction may have resulted from pollution in the port of Oran and increased when temperature exceeded critical thresholds for gametogenesis. To conclude, gamete degeneration and spawning cessation because of coastal pollution and global warming could threaten M. galloprovincialis recruitment, and ultimately the shellfish economy, and could distort biomonitoring strategies using mussels

The impacts of seawater physicochemical parameters and sediment metal contents on trace metal concentrations in musselsa chemometric approach

The concentrations of Al, Ba, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Sr, Zn, and Hg were studied in Mytilus galloprovincialis collected from the coastal area of Montenegro. The impact of seawater temperature, salinity, dissolved oxygen, total organic carbon (TOC), and metal content in sediment samples on the metal contents in mussels collected from three locations in four different seasons was analyzed by a Pearson correlation coefficient (r), principal component analysis (PCA), and cluster analysis (CA). These analyses were used to discriminate groups of samples, elements, and seawater parameters, according to similarity of samples chemical composition in different seasons, as well as the impact of seawater parameters and surface sediment composition on the mussels' element concentrations. Synergistic interactions occurred between seawater TOC, Fe, and Al concentrations in mussels. Compared with other studies, which are usually performed under constant laboratory conditions where mussels undergo only one stress at a time, this study was performed in nature. The analyses showed the importance of considering simultaneously acting environmental parameters that make determining of separate impacts of each factor selected very difficult and complex