In Tunisia, fluctuations in the water cycle over the last centuries, driven by climate variability and human activities, have been particularly pronounced in the arid regions of the south. The El Bibane and El Grine lagoons constitute natural archives that can be used to reconstruct extreme hydrological events through the sedimentary deposits they leave behind. Previous studies have identified major floods during the last several millennia, which were responsible for the deposition of fine-grained continental sediments transported by ancient wadis. However, the impact of these events on benthic communities remains poorly understood. This research activity aims to investigate the relationships between sediment inputs and the distribution of mollusks and benthic foraminifera in the El Bibane and El Grine lagoons. The working hypothesis is that fine sediments resulting from flood events favor tolerant lagoonal species, whereas periods of hydrological stability promote the development of more stable marine faunal communities. The analysis of fauna along sediment cores will therefore provide insights into the evolution of the lagoonal ecosystem and its response to extreme hydrological events.