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doi:10.2204/iodp.proc.310.111.2007 Microbiology1Expedition 310 Scientists2IntroductionPrevious research on drill cores from the barrier reef-edge of Tahiti revealed the presence of microbialites, which are generally interpreted as forming during the last stage of encrustation over dead coral colonies. Microbialites are a major structural component of the reef sequence, contributing as much as 80% of the reef framework (Camoin and Montaggioni, 1994; Camoin et al., 1999). Microbialites are, based on the definition of Burne and Moore (1987), “organosedimentary deposits that have accreted as a result of a benthic microbial community trapping and binding detrital sediment and/or forming the locus of mineral precipitation.” Although Tahiti microbialites show a strong relationship between microbial activity and mineral precipitation, little is known about the microbial mechanisms associated with their formation. Neither a mineralogical nor sedimentological approach can provide precise information concerning the community of microorganisms that is involved in the processes associated with this unusual formation of macroscale structures. In order to have a better understanding of the microcosms of the Tahiti reef environments, it is important to verify whether there are still-living microorganisms preserved in reefs (i.e., survivors of those responsible for the formation of microbialites). If they are found to be present, the next questions are what types of microorganisms are present and in what abundances, and which of them are actually actively participating in the biogeochemical processes? |