Holocene environmental changes in the highlands of Yemen revealed by Ostracod (Crustacea) stratigraphy

Abstract The region encompassing the Sahara and the Arabian Peninsula has seen dramatic changes in Holocene moisture availability. While the highlands of Yemen are sensitive to moisture dynamics, their history remains poorly known. This study provides new information on Holocene environmental change in the Yemeni highlands through analyses of the lithostratigraphy and ostracod stratigraphy of two localities. The diversity and abundance of ostracod populations serve as key environmental indicators, reflecting stability and change in aquatic habitats. Six time periods are identified, each representing distinct phases of environmental and climatic change. Undated gravelly fine sands, possibly of late-glacial or Early Holocene age, indicate dry conditions. Subsequent stages indicate a progression of moister conditions and warmer climates characterized by the formation of ponds and lakes and fluctuations in water availability. Shifts occurred between oligotrophic and eutrophic conditions, and between desiccation trends and wetter conditions. We found the taxonomic composition of ostracod populations in Yemen’s highlands to include species from mountainous regions of Africa and the broader Palaearctic. This research aligns with previously reported data and expands our understanding of past ecosystems and climatic conditions in highland Yemen.