Assessing modern radiolarian distribution in the marginal seas is essential for understanding its relationship to hydrographic and environmental variables, upon which subsequent interpretation of past radiolarian records can be made reliably. Here, we combine published radiolarian assemblages in 69 surface sediments from the Japan Sea with those obtained from 15 new surface sediments in this study to determine the modern distribution of radiolarians. The Tsushima Warm Current (TWC) taxa are only found in the south of the Subpolar Front. The results of redundancy analysis confirm that the temperature at 10 m depth (temperature_10m) is the main factor controlling the spatial variability of TWC taxa. The water depth plays a key role in affecting the abundances of Japan Sea Proper Water (JSPW) Assemblage including Larcopyle buetschlii Dreyer (adult), Cycladophora davisiana Ehrenberg, and Actinomma group. The JSPW Assemblage can be used as a reliable indicator of ventilation changes in the Japan Sea. Based on the newly developed TWC taxa and JSPW Assemblage, we further reconstructed the water column structure in the central Japan Sea over the past 25 ka. There was weak ventilation in the central Japan Sea even during the Last Glacial Maximum (LGM), although a distinct decrease in the TWC inflow resulted in surface-water freshening and water column stratification. After the LGM, the TWC taxa together with JSPW Assemblage resumed in the central Japan Sea at the 19 ka meltwater pulse (MWP). The MWP-1A was clearly marked by an enhanced intrusion of the TWC. Synchronously, JSPW was ventilated deeply down after ~14.6 ka attaining to the similar level of the Holocene as a result of changing sea surface conditions. Along with the continuing sea-level rise, the matured TWC entered the Japan Sea at 7 ka and since then the modern hydrographic condition has been established. We suggest that the changes in the sea level and TWC strength predominantly determined the surface hydrography and deep ventilation in the central Japan Sea since 25 ka, and the TWC might have notably affected the Japan Sea since the Bølling-Allerød.

评估边缘海现代放射虫的分布对于了解其与水文和环境变量之间的关系至关重要，在此基础上可以可靠地对过去的放射虫记录进行后续解释。在这里，我们结合已发表的来自日本海的69种表层沉积物中的放射虫组合和本研究中从15种新的表层沉积物中获得的放射虫组合，以确定放射虫的现代分布。对马暖流（TWC）分类群仅在次极锋的南部。冗余分析的结果证实，深度10 m的温度（温度_10m）是控制TWC分类单元空间变异性的主要因素。水深在影响日本海自来水（JSPW）组件的丰度方面起着关键作用，包括Larcopyle buetschlii Dreyer（成人），Cycladophora davisiana Ehrenberg和Actinomma组。JSPW组件可以用作日本海中通风变化的可靠指标。基于新开发的TWC分类单元和JSPW组合，我们在过去25 ka的时间内进一步重建了日本中部海域的水柱结构。尽管TWC流入量明显减少，导致地表水新鲜化和水柱分层，但即使在上次冰期最高期（LGM）期间，日本中部海域的通风仍然较弱。LGM之后，TWC类别和JSPW组合在日本中海的19 ka融水脉动（MWP）恢复。MWC-1A的明显标志是TWC的入侵有所增强。同时，由于海面条件的变化，JSPW在〜14.6 ka之后达到了全新世的相似水平，因此深层通风。随着海平面的不断上升，成熟的TWC在7 ka进入日本海，此后便确立了现代水文条件。我们建议，自25 ka开始，海平面和TWC强度的变化主要决定了日本中部海域的表面水文和深层通风，而自Bølling-Allerød以来，TWC可能对日本海产生了显着影响。