Microtaphonomy of organic materials at sediment-water interface-Experimental Research for establishing paleoenvitonmental proxies in consideration to microbial processes-

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Organic materials produced at sea surface are deposited on sea floor and are consumed by benthic organisms at Sediment-water Interface(SWI). This research aims to elucidate how micro-and meio-benthos consume organic materials at SWI through in situ and laboratory experiments.In situ experiments were conducted at the central part of Sagami Bay. Carbon 13 labeled single-celled phytoplankton (Dunaliella and Chaetoceros) and bacteria were supplied on sediment surface of feeding apparatus. In total, eight-set of apparatuses were situated on the sea floor. Three apperatuses were recovered every two days until 6 days have passed. Meiobenthos, both foraminifera and metazoan meiobenthos were picked under microscope in the laboratory. δ ^<13>C values of each species were measured with GC-mass spectrometer. Benthic foraminifera digested fresh food materials rapidly. Eighty to Ninety percentages of digested food materials are calculated to mineralize into carbon dioxide gas through respiration. Rests of them may assimilate into foraminiferal cell materials. Responses in food materials are different from species to species, in particular to each feeding behavior. Phytodetrital feeder should be most quick responder in comparison to deposit feeder. There are no specific bacteriovore among foraminiferal species that could analyze during this study.In situ measurements have also conducted at Sagami Bay center using both sensor microelectrode and planer optode systems that have assembled in lander system. A few millimeter to 1 cm thick oxygenated layer is developed at SWI. Two cm scale patchness of dissolved oxygen was observed at SWI. This may correspond well to 3D-distributional patterns of benthic foraminifera. We developed a highly sensitive optode film during this research. It can detect behaviors of benthic foraminifera at SWI.Through this research, we can conclude that foraminifera act a big role as primary consumer of organic materials at SWI.