DEVELOPMENT OF A NEW,AUTOMATIC SAMPLERF OR COLLECTION OF DEEP-SEA HYDROTHERMAL FLUIDS

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A.DEVELOPMENTO OF A NEW,AUTOMATIC HYDROTHERAMAL FLUID SAMPLER(1) The sampler was designed to employ a shape memory alloy that allows simultaneous sensing of high temperature and activatation of the valve and the suction mechanisms.(2) The sampler was designed to be be down-sized and down-weighted for easier manipulation by submersibles and other deep-sea vehicles. It was thus designed to collect 100 ml of a fluid sample, to be cylinder-shaped, and to be made mostly of aluminum and Teflon.(3) A shape memory alloy was prepared specifically for the use of the sampler.(4) The sampler was assembled and tested in the land-based laboratory.B.IN SITU TEST OF THE NEW,AUTOMATIC HYDROTHERMAL FLUID SAMPLER(1) The sampler was tested, with thesubmersible Shinkai 2000, at a deep-sea hydrothermal vent in a submarine vilcanic crater (1374m deep), which emitted super-heated fluid of up to 298ﾟC.The fluid collection was successful.(2) Abundant microorganisms was observed in the fluid collected by the sampler. The microbial abundance was as high as 10^5-10^6ml^<-1>, which is 10-100 times higher than those known for similar water depth. DNA was recovered from the collected microorganisms, and 16SrDNA sequences were analyzed therefrom. Certain 16SrDNA was found to be closely realted to that of Shwanella sp., which is a barophilic species.(3) Chemical analysis of the fiuids collecte by the sampler revealed that the much seawater was entrained into the sample fluid. Our sampler was designed to collect theoretically 100% pure hydrothermal fluid, but it did not. The ratio of entrainment was 48-90%. The reason of the seawater entrainment is supposed to be that the suction was too fast to collect only the hydrothermal fluid moderately.