Latest Holocene paleoenvironmental reconstruction of three Cameroonian lakes, SW Africa

This study reconstructs the latest Holocene (~ last 1 ka) environmental evolution of three Cameroonian lakes: Simbock (Yaoundé), Ossa (Dizangué), and Ngaoundaba (Ngaoundéré), based on a multiproxy approach that integrates sedimentological, diatom, and pollen data within a radiocarbon-based chronological framework. The calibrated radiocarbon ages were expressed as 2σ intervals (95.4%) and discussed using CE chronology. The diatom and pollen records revealed pronounced hydrological variability, alternating between humid and dry phases, broadly corresponding to the Medieval Climate Anomaly (ca. 900–1200 CE) and the Little Ice Age (ca. 1400–1700 CE). Four distinct paleohydrological phases were identified in the southern basins (Ossa and Simbock), reflecting variations between oligotrophic and eutrophic conditions, and transitions from acidic to alkaline, clearer waters dominated by Aulacoseira species. In Lake Simbock, episodic drying and nutrient enrichment indicate reduced inflow and eutrophication in a young artificial basin. In the Adamawa highlands (Lake Ngaoundaba), three depositional phases recorded initially stable oligotrophic conditions, followed by a brief dry period and a subsequent highstand associated with renewed humidity and tychoplanktonic dominance. These multiproxy results highlight the sensitivity of tropical lakes to ITCZ migrations, monsoon variability, and localized catchment processes. The late Holocene record also revealed increasing anthropogenic influence through deforestation, burning, and soil erosion. The findings of this study will improve our understanding of hydroclimatic variability and ecosystem resilience in Cameroon’s central and southern regions.