Data from: Response of subtropical submarine-cave ecosystem to Holocene cave development and Asian monsoon variability

A submarine cave is a unique environment, which is dark, food-limited, semi-isolated from the outside, and sheltered from wave actions. However, our knowledge on the long-term change in submarine cave ecosystem remains limited. Here we document the community-scale responses towards long-term change in a submarine cave, Daidokutsu, in Okinawa, southern part of Japan. Using both metazoans (ostracods and bivalves) and protozoans (larger benthic foraminiferans) in two sediment cores obtained from the cave, the past 7000-year faunal and diversity changes are reconstructed. All taxonomic groups showed long-term, gradual linear change of the faunal composition from more open-water taxa dominant one to more cave taxa dominant one, and ostracods showed short-term variability of species diversity. The long-term faunal trend probably reflects gradual isolation of the cave and its ecosystem due to coral reef development (i.e., development of the cave ceiling) during the periods of the Holocene transgression and subsequent sea-level highstand. The short-term diversity changes show substantial similarity to centennial–millennial scale Holocene Asian monsoon variability. Ostracod species diversity peaks tend to correspond to the periods of strong East Asian winter monsoon. The results indicate that limestone submarine cave ecosystem, an important cryptic habitat, has been gradually developed during the Holocene and may be sensitive to rapid climate changes.海底洞穴（submarine cave）是一类独特的生境：环境黑暗无光、食物资源匮乏、与外界半隔绝，且不受波浪作用侵扰。然而目前学界对海底洞穴生态系统的长期变化仍知之甚少。本研究针对日本南部冲绳的Daidokutsu海底洞穴，记录了其群落尺度下对长期环境变化的响应特征。研究利用采自该洞穴的两处沉积岩芯中的后生动物（metazoans，包括介形类和双壳类）与原生动物（protozoans，即大型底栖有孔虫），重建了过去7000年的动物群组成与多样性变化历史。所有分类类群的动物群组成均呈现长期、渐进的线性变化趋势：从以开阔水域类群占主导的组合，逐步转变为以洞穴特有类群占主导的组合；其中介形类的物种多样性还表现出短期波动特征。这种长期的动物群变化趋势，可能反映了全新世海侵（Holocene transgression）及随后海平面高水位期（sea-level highstand）内，珊瑚礁发育（即洞穴顶板的形成过程）导致该洞穴及其生态系统逐步与外界隔绝的过程。介形类的短期多样性变化，与全新世亚洲季风百年-千年尺度的波动特征具有显著相似性。介形类物种多样性的峰值时段，往往对应东亚冬季风（East Asian winter monsoon）增强的时期。本研究结果表明，作为一类重要的隐蔽生境，石灰岩海底洞穴（limestone submarine cave）生态系统在全新世期间逐步形成，且可能对快速气候变化较为敏感。