This study clarified the centennial-scale changes in meiobenthic bay ostracod assemblages in Japan over the past approximately 3000 years with relation to various human-induced and natural environmental factors. These factors were inferred via integrated multiproxy methods of high-resolution geological analyses of core sediments obtained from a shallow bay off a coastal plain, along with literature surveys of archeological and historical records. Five intervals were defined based on multivariate analyses of ostracod assemblages. The ostracod assemblage was stable before around the 6th century because of aggradational sedimentation related to gradual increases in sea level. Since then, the composite factors such as the development of a sandy spit near the study site, stable sea level, regional tectonics, regional centennial-scale climatic change possibly related to El Niño Southern Oscillation (ENSO), and flood mitigation by human settlement in the coastal plains triggered the formation of tidal flats and subtidal sandy areas with seagrass beds. This has markedly influenced offshore bay ostracod assemblages since around the 12th century. Anthropogenic impacts, such as reclamation and various artificial constructions since the late 20th century caused the disappearance of seagrass beds, input of coarser sediment into offshore bays, and increased nutrient loads. Therefore, ostracod assemblages have changed drastically. Ostracod assemblages near the boundary between land and sea have been affected by multiple complex factors, such as regional climate and depositional and human-induced processes during the Late Holocene.

本研究阐明了过去约 3000 年来日本小型底栖海湾介形类群的百年尺度变化与各种人为因素和自然环境因素的关系。这些因素是通过对从沿海平原浅海湾获得的核心沉积物进行高分辨率地质分析的综合多代理方法，以及对考古和历史记录的文献调查。根据介形虫组合的多变量分析定义了五个区间。由于与海平面逐渐升高有关的加积沉积作用，介形类生物群在 6 世纪左右之前是稳定的。此后，研究地点附近沙嘴的发育、稳定的海平面、区域构造、可能与厄尔尼诺南方涛动（ENSO）有关的区域百年尺度气候变化以及人类住区缓解洪水等综合因素沿海平原引发了具有海草床的潮滩和潮下沙区的形成。自 12 世纪左右以来，这对近海海湾的介形虫组合产生了显着影响。自 20 世纪后期以来，人为影响，例如填海造地和各种人工建筑，导致海草床消失，将较粗的沉积物输入近海海湾，并增加养分负荷。因此，介形虫组合发生了巨大变化。陆海边界附近的介形类组合受到区域气候、晚全新世沉积和人为过程等多种复杂因素的影响。并增加营养负荷。因此，介形虫组合发生了巨大变化。陆海边界附近的介形类组合受到区域气候、晚全新世沉积和人为过程等多种复杂因素的影响。并增加营养负荷。因此，介形虫组合发生了巨大变化。陆海边界附近的介形类组合受到区域气候、晚全新世沉积和人为过程等多种复杂因素的影响。