12:15 PM - 12:30 PM
[BPT24-06] Confirmation of chemosynthetic activities of Bathymodiolus septemdierum through laboratory culture
Keywords:deep-sea biology, chemosynthetic ecosystem
Individuals of B. septemdierums are captured during dive series of ROV Hyper-dolphin system of two cruises of R/V Natsushima operated by Japan Agency for Marine-Earth Science and Technology (JAMSTEC) in April of 2012, in March of 2013 and in April of 2014. The samples are collected around Myojin-Sho submarine volcano on the Izu-Ogasawara Ridge (1224-1285m depth). Collected samples were kept under 4℃ water tank in an on-board low-temperature room till the end of cruise. Then, the individuals are immediately transfer to on-land laboratory water tank after cruise to avoid the unfavorable environment. The water tank has been designed as chemostat system with H2S supply to maintain symbiotic bacteria of deep-sea chemosynthetic animals. The individuals are cultured in this system for three months and fourteen months respectively. Here, previous study shows the symbiotic bacteria disappeared within three months without H2S source. Therefore, we prefer to confirm the bacteria hopefully maintained more than three months in our chemostat system or not. For the purpose, carbon isotope labeling experiments were carried out to clarify the symbiotic bacterial activity. The carbon isotope will be taken by B. septemdierums if the symbionts are active. We compare the carbon isotopic uptake between under H2S positive and under H2S negative (control) conditions. Meantime, dissolved oxygen (DO) of each cultivation was monitored to check health and activity of individuals. The results show the labeled 13C was taken into organic matter in both gills and foot especially under H2S positive condition. The isotopic measurement of compound specific carbon isotopes in fatty acid show positive result. By this result, we consider the labeled carbon should be incorporated to the cell membrane of host animal. We summarize the symbiotic bacteria have been maintained for fourteen months in the chemostat system.