The northern Bay of Biscay has previously proven its great potential for recording the ‘Fleuve Manche’ paleoriver (i.e., the largest Pleistocene river in Europe) fluvio-glacial activity. In this study, new dinoflagellate cyst (dinocyst) analyses have been carried out at sub-centennial resolution in core MD13–3438 to reconstruct the deglacial history of the ‘Fleuve Manche’ paleoriver runoff coupled with European Ice Sheets (EIS) fluctuations across Heinrich Stadial 1 (HS1: 18.2–14.6 ka BP), a key extreme climatic event of the last glacial period. Prior to Heinrich Event (HE) 1 (16.7–14.6 ka BP), the onset of HS1 (18.2–16.7 ka BP) appears here marked by enhanced ‘Fleuve Manche’ paleoriver runoff, materialized by laminated deposits. Our work suggests a novel sub-centennial scale subdivision of the early HS1 (laminated) interval into 5 sub-phases when episodes of substantial fluvio-glacial delivery concomitant with warm summers alternate with episodes of moderate runoff associated with extended cold winters. We argue that multidecadal seasonal changes played a key role in the hydrological regime of western Europe during this HS1 interval, with the retreat of the southern limb of the EIS, and associated influx of meltwater and fluvio-glacial delivery, which were strongly influenced by those multidecadal changes in seasonality. Interestingly, our paleoclimatic record not only evidences the crucial role of seasonality in controlling climate and hydrological variations during HS1 but also shows a remarkable echo with reconstructions from the western Mediterranean Basin, highlighting common climate forcings at regional scale during the last deglaciation.

比斯开湾北部先前已证明其记录“曼什河”古河流（即欧洲最大的更新世河流）冰川活动的巨大潜力。在这项研究中，在核心 MD13-3438 中以亚百年的分辨率进行了新的甲藻囊肿 (dinocyst) 分析，以重建'Fleuve Manche'古河流径流的冰消历史以及整个 Heinrich Stadial 的欧洲冰盖 (EIS) 波动1 (HS1: 18.2–14.6 ka BP)，末次冰期的一个关键极端气候事件。在海因里希事件 (HE) 1 (16.7–14.6 ka BP) 之前，HS1 (18.2–16.7 ka BP) 的开始出现在这里以增强的“ Fleuve Manche”为标志古河流径流，由层状沉积物形成。我们的工作建议将早期 HS1（分层）间隔进行新的亚百年规模细分，将其分为 5 个亚阶段，此时伴随着温暖夏季的大量河流冰川输送事件与与延长的寒冷冬季相关的温和径流事件交替出现。我们认为，在这个 HS1 间隔期间，随着 EIS 南翼的撤退，以及相关的融水和河流冰川输送的流入，在这个 HS1 区间内，数十年的季节性变化在西欧的水文状况中发挥了关键作用，这些变化受到了这些因素的强烈影响。季节性的多年变化。有趣的是，