Holocene Diatom Records and Coastal Environmental Dynamics in East Asia

The Holocene epoch represents a critical phase of climatic stabilization and intensified human–environment interaction, particularly across the dynamic coastal margins of East Asia. Diatom assemblages preserved in marine and lacustrine sediment cores provide high-resolution proxies for reconstructing past sea-level fluctuations, monsoon variability, salinity gradients, and coastal geomorphological evolution. This study synthesizes Holocene diatom records from major East Asian coastal regions, including estuarine, deltaic, and lagoonal systems, to examine patterns of environmental change and ecosystem response. Variations in species composition, diversity indices, and salinity-tolerant taxa reveal shifts associated with transgressive–regressive cycles, monsoon intensification during the mid-Holocene climatic optimum, and late Holocene anthropogenic influences. The findings demonstrate that diatom-based reconstructions offer robust insights into the timing and magnitude of coastal environmental transformations. Understanding these long-term dynamics enhances predictive models of coastal vulnerability under ongoing climate change and sea-level rise in East Asia.