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

本研究旨在通过现场实验和实验室实验，追踪底栖生物有机质在沉积物-水界面(SWI)沉没有机质的消耗过程。现场试验是在相上湾和田边湾进行的。1.利用载人潜水器采集底栖云母层中的悬浮有机物。用气相色谱仪测定有机成分进行鉴定。2.采用多取样器采集表层原状沉积物。岩心样本每0.25 cm切片一次。进行了地球化学分析，以表征化学环境。根据区系组成估算了小型底栖动物的生物量。3.利用“新开2000”号载人潜水器在相模湾进行了现场摄食试验。用碳13标记的单细胞藻类作为食物原料。4.在实验室测定了呼吸速率和生物量。小型底栖动物对有机碳的再矿化速率是根据摄食率、生物量和呼吸速率计算的。底栖生物根据自己的微生境偏好对下沉的有机物质做出反应。例如，浅水区系物种反应迅速，并摄取大量有机物质。底栖有孔虫的数量随着沉积物中脂肪含量的变化而变化，尽管不同物种的反应不同。底栖小型动物消耗了50%以上的沉降性有机物。显然，底栖生物在南海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.