Dynamics of Sediment-Water Interface

“底-上层耦合”是贫营养深海海底环境中物质循环和生态的重要方面，但富营养深海环境中是否存在“底-上层耦合”尚不清楚。富营养化的深海环境主要分布在海洋边缘。为了了解日本中部相模湾太平洋西部边缘富营养化深海环境中的季节性碳循环，开展了跨学科研究。1997年至1998年，我们在相模湾中部的永久站收集了地表水样本、卫星照片、沉积物陷阱系泊和多个核心样本的数据。在相模湾初岛附近的一个实时深海海底观测站，还通过视频图像观察了海底的星云层。在1997年的2月中旬到5月，可以看到明显的春花。由于再悬浮物质的影响，沉积在沉积物圈闭中的质量通量没有显示出明显的春季水华信号。然而，只有在春季底栖星云层中才观察到密集的悬浮颗粒云。这一现象与春华后植物碎屑物质的增加是相对应的。大约在春华开始两周后，沉积物表面开始形成植物碎屑层。仅在植物碎屑层存在时，沉积物顶部2cm处检测到叶绿素- α。原生动物和后生小底栖动物在植物碎屑沉积后密度增加。即使在富营养化的边缘海洋环境中也确实观察到“底栖-远洋耦合”。

"Benthic-pelagic coupling" is a key aspect of both material cycles and ecology in oligotrophic deep-sea floor environments, However, it remains unclear whether "bentho-pelagic coupling" exists in eutrophic deep-sea environments. Eutrophic deep-sea environments are mainly located along ocean margins. Interdisciplinary research was carried out to understand seasonal carbon cycling in a eutrophic deep-sea environment along the western margin of the Pacific, in Sagami Bay, central Japan. We collected data from surface water samples, satellite photographs, sediment trap moorings and multiple core samplings at the permanent station in the central part of Sagami Bay between 1997 and 1998. Bottom nepheloid layers were also observed through video images, which were recorded at a real-time deep-sea floor observatory off Hatsushima in Sagami Bay.Distinct spring blooms were observed during mid-February through May in 1997. Mass fluxes deposited in sediment traps did not show distinct signals of spring blooms because of the influence of resuspended materials. However, dense clouds of suspended particles were observed only in the spring in benthic nepheloid layer. This phenomena corresponds well to the increase of phytodetrital matters after the spring bloom. A phytodetrital layer started to form on the sediment surface about two weeks after the start of the spring bloom. Chlorophyll-alpha was detected in the top 2 cm of the sediment only during presence of a phytodetritus layer. Protozoan and metazoan meiobenthos increased in densities after phytodetritus deposition. "Benthic-pelagic coupling" was certainly observed even in a eutrophic marginal ocean environment.