Development of Biomonitoring System using Deep-Sea Organisms in a Pressurized Chamber.

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First of all, we established a pressurized chamber, in which a deep-sea meiofaunal organisms such as nematodes could be cultured for at least 2 weeks. The chamber can control the pressure inside the chamber up to 200 atm. In addition, it is possible to change the culturing sea water without decompression. Using this chamber, we tried to measure the survival of deep-sea nematodes in a high concentration of CO2, and found they are as sensitive as shallow water species to the low pH environment. In addition to the survival rate, we tried to measure the respiration rate of the meiofaunal organisms using a plastic that emits fluorescent light the intensity of which depends on the dissolved oxygen concentration of the sea water. The method seemed promising, but the absolute figure was not obtained because the pressure affected the light intensity. Further research is needed to calibrate the light intensity to the dissolved oxygen concentration in a high-pressure environment. We tried to cult … More ure foraminifers as well as nematodes. The formers are more interesting because they have a calcium carbonate external skeleton, which easily will be dissolved in low pH water. However, because the calcium carbonate exoskeleton is easy to be dissolved in high-pressure water, too, it was impossible to observe the biological effects of low pH on foraminifers in a high- pressure condition. In 1997, the head investigator moved from the Ocean Research Institute, the University of Tokyo, to Seto Marine Biological Laboratory, Kyoto University. With this movement, we concentrated to observe the effects of low pH on various marine organisms that have calcium carbonate skeleton more precisely over a longer period. This experiment revealed that as low as 2000 ppm of CO2 strongly affects on the physiological condition of marine organisms. For example, the weight of the shell of a species of snail decreased significantly, and only a half of individuals could survive over two months of experiment. The result suggests that the estimated future concentration of CO2 (700 ppm) might affect seriously on marine organisms, and more precise research is necessary to understand the environmental impact of increased concentration of CO2 in the atmosphere. Less