冷湧水に伴う底生有孔虫 : 特徴と適応機構についての考察

概要

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Faunal characteristics and adaptations of benthic foraminifera associated with cold seepages are discussed. A few species are known from cold seepages where an anoxic environment was produced due to methane or hydrogen sulfide gas. Neither of the two species in Sagami Bay is endemic to the seepages : one is common even in oxic bottom, and the other is present in anoxic microenvironments below the surface oxic layer. There are two possibe explanations for the survival of benthic foraminifera in anoxic/euxinic cold seepage environments. First, some foraminifera may be able to tolerate anoxic environments, using anaerobic respiration system. However, in this case, the foraminiferal tests should dissolve due to organic acids produced during anaerobic respiration. Second, foraminifera may be in symbiosis with sulfide oxidizing bacteria. Larger chemosynthetic animals house sulfide oxidizing bacteria. It is possible that foraminifera can also house bacteria in their cells, although up to the present time few foraminifera have been reported to have such bacteria. Of the two ideas, I believe the second is more likely to be true, and in this contribution I explore the possibility of sulfide oxidizing bacterial symbionts in cold seepage foraminifera.
日本古生物学会の論文
1996-06-30