The Mediterranean region experienced several humid periods in the past, particularly during the Early and Middle Holocene. These phases are evidenced by a decrease in Mediterranean salinity and changes in vegetation observed across North Africa, the Middle East, and southern Europe. During sapropel episodes, increased freshwater inputs promote water-column stratification and the accumulation of organic matter in the deep eastern Mediterranean. Its degradation leads to increased CO₂ concentrations, a decrease in pH, and acidification of deep waters, which reduces calcification in marine organisms such as foraminifera. This research activity aims to investigate changes in the test mass of planktonic foraminifera over the last 20,000 years using sediment cores collected from the main Mediterranean basins. The objective is to determine whether the acidification observed during sapropel episodes was restricted to the eastern basin or affected the Mediterranean as a whole, while also investigating its relationship with the development of anoxic conditions in the deep marine environment.