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实验室实验追踪沉积物-水界面（SWI）底栖生物对沉积有机质的消耗过程。在相模湾和田边湾进行了田间试验。1.利用载人潜水器采集了底栖雾状层中的悬浮有机物。用气相色谱仪测定有机组分进行鉴定。2.用多芯取样器采集表层原状沉积物。每隔0.25 cm对岩心样品进行切片。进行了地球化学分析，以表征化学环境。小型底栖生物的生物量估计根据区系组成。3.在相模湾用“Shinkai 2000”号载人潜水器进行了原位摄食实验。用碳13标记的单细胞藻类作为食物材料供应。4.呼吸速率和生物量都在实验室测量。根据小型底栖生物对有机碳的吸收速率、生物量和呼吸速率计算了小型底栖生物对有机碳的再矿化速率。例如，浅水底栖物种反应迅速，摄取大量有机物。底栖有孔虫数量的变化与沉积物中脂质含量的变化是一致的，尽管不同物种的反应不同。50%以上的下沉有机质被底栖小型底栖生物消耗.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.