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Title :Endolithic microbes within calcium cabonate skeletons of reef-building corals
Title alternative :造礁サンゴ骨格内に生息する微生物群に関する基礎研究
Authors :山崎, 征太郎
Authors alternative :Yamazaki, Seitaro
Issue Date :Mar-2010
Abstract :The establishment of obligate symbiotic relationship with photosynthetic dinoflagellate (zooxanthellae) is essential for reef-building corals in adaptation to natural oligotrophic environments. Breakdown of the symbiotic relationship with zooxanthellae leads to coral bleaching that is pronounced under stress conditions. Ecological studies have suggested that susceptibility to bleaching and the ability to recover from bleaching vary among coral species. However, it is yet unconfirmed what endogenous factors make such differences. Here I describe endolithic microbe within coral skeleton as a novel factor that may account for the diversity in response to environmental stimuli. Endolithic microbial communities were investigated in skeleton of the massive coral Goniastrea aspera that is one of the bleaching tolerant species. “Halomicronema sp.”, a moderately halophilic and thermophilic cyanobacterium, was found in the skeleton of G. aspera. Comparative study of the endolithic microbial flora within skeletons of G. aspera showed that bacterial diversity was much higher in the coral skeletons collected from oligotrophic environments than those from eutrophic ones. The endolithic microbial community included sulfate-reducing bacteria and resembled microbial mats commonly found in harsh environments. To explore beneficial effects of endolithic microbes on coral physiology, the branching coral Acropora digitifera with and without endolithic algae were exposed to high irradiance of visible light. The presence of endolithic algae within the skeletons was found to suppress photoinhibition of photosynthesis in the host tissue. The results suggest that endolithic algae have a photoprotective role in the coral photosynthesis. The interactions between reef-building corals and endolithic microbes are discussed in terms of secondary or facultative symbiotic relationship.
Type Local :学位論文
Publisher :山崎征太郎
URI :http://hdl.handle.net/20.500.12000/18547
Grant id :18001理工研第185号
Date of granted :2010-03-23
Degree name :博士(理学)
Grantor :琉球大学
Appears in Collections:Doctoral Dissertation (Graduate School of Engineering and Science)

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