Selective consumption and taphonomy by benthic organisms at sediemnt-water interface --Establishment of new paleoceanographic prixies through experimental methods--

本研究旨在通过原位和室内实验，追踪沉积物-水界面（SWI）底栖生物对下沉有机质的消耗过程。野外试验分别在相模湾和田边湾进行。利用载人潜水器对底栖网兜层悬浮物进行了采集。用气相色谱仪测定有机成分进行鉴定。2. 地表未扰动沉积物采用多层覆盖收集。岩心样品每0.25 cm切片一次。对化学环境进行了地球化学分析。根据区系组成估算了小底栖动物的生物量。3. 利用“新海2000”载人潜水器在相模湾进行了原位饲养试验。用碳13标记的单细胞藻类作为食物原料供应。4. 在实验室测量呼吸速率和生物量。小底栖生物对有机碳的再矿化速率由吸入量、生物量和呼吸速率计算。底栖生物根据自己的微生境偏好对下沉的有机物质作出反应。例如，浅水动物反应迅速，摄取大量有机物。底栖有孔虫的数量随沉积物中脂质含量的变化而变化，尽管反应因物种而异。超过50%的下沉有机质被底栖动物消耗。很明显，底栖生物在SWI周围的深海生态系统中发挥着重要作用。

This research aims to trace consumption process of sinking organic matter by benthic orgamisms at Sediment-Water Interface (SWI) both through in situ and laboratory experiments. Field experiments were carried out both at Sagami Bay and Tanabe Bay. 1. Suspended organic matters in benthic nepheloid layer were collected by manned submersible. Organic conpositions were measured by gas chromatograph for identification. 2. Surface undisturbed sediments were collected with multiple corer. Core samples were sliced every 0.25 cm. Geochemical analyzes were made for characterizing chemical environments. Biomasses of meiobenthos were estimated according to faunal compositions. 3. In situ feeding experiments were carried out at Sagami Bay with manned submersible "Shinkai 2000". Single celled alga that were labelled with carbon 13 were supplied as food materials. 4. Both respiration rates and biomasses were measured at the laboratory. Remineralization rates of organic carbon by meiobenthos were calculated from intake rates, biomass and respiration rates.Benthic organisms respond to sinking organic materials according to their own microhabitat preferences. For instance, shallow infaunal species respond rapidly and intake large ammount of organic matter. Numbers of benthic foraminifera changes in harmony to lipid contents within sediments, even though response differ from species to species. More than 50 % of sinking organic matters were consumed by benthic meiofauna. It is clear that benthic organisms play a large role at deep sea ecosystems around SWI.