M. galloprovincialis reproduces via spawning, which is triggered by water temperature and food availability. Their spawning cycle is not universal and varies throughout the species' distribution as different environmental conditions and triggers may be found at each location.
Studies in Spanish bays have generally observed one mass spawning event with two peaks per year, occurring in spring to early summer. However, smaller spawning events can also occur in the same year.
M. galloprovincialis utilizes environmental prey refuges to avoid predation. In New Zealand, this refuge can take the form of salinity stratification of fjords. The mussels concentrate in low salinity levels which their predators cannot inhabit. Juvenile mussels are most affected by predation, with smaller predators (such as the sea star, Patiriella regularis, and the small wrasse, Notolabrus celidotus) targeting this life stage. Therefore, the juveniles in low salinity zones which exclude these predators are most likely to survive to adulthood.
However, the low salinity can also be harmful for the mussels. Below about 9 PSU, M. galloprovincialis exhibits physiological stress and increased mortality rates, especially in younger mussels.
The Mediterranean mussel is susceptible to heat waves and other forms of high ocean temperatures. Populations of M. galloprovincialis exhibit a 50% mortality rate at 27.5°C-29°C. At high temperatures the mussels have reduced filtration rates and a reduced ability to feed. This is especially of concern for aquaculture.
