Subseafloor Archaea reflect 139 kyrs of paleodepositional changes in the northern Red Sea
AuthorsMore, Kuldeep D.
Tierney, Jessica E.
Coolen, Marco J.L.
KAUST Grant NumberOCRF-SP-WHOI-2013
Permanent link to this recordhttp://hdl.handle.net/10754/679204
MetadataShow full item record
AbstractThe vertical distribution of subseafloor archaeal communities is thought to be primarily controlled by in situ conditions in sediments such as the availability of electron acceptors and donors, although sharp community shifts have also been observed at lithological boundaries suggesting that at least a subset of vertically stratified Archaea form a long-term genetic record of coinciding environmental conditions that occurred at the time of sediment deposition. To substantiate this possibility, we performed a highly resolved 16S rRNA gene survey of vertically stratified archaeal communities paired with paleo-oceanographic proxies in a sedimentary record from the northern Red Sea spanning the last glacial–interglacial cycle (i.e., marine isotope stages 1–6; MIS1-6). Our results show a strong significant correlation between subseafloor archaeal communities and drastic paleodepositional changes associated with glacial low vs. interglacial high stands (ANOSIM; R =.73; p =.001) and only a moderately strong correlation with lithological changes. Bathyarchaeota, Lokiarchaeota, MBGA, and DHVEG-1 were the most abundant identified archaeal groups. Whether they represented ancient cell lines from the time of deposition or migrated to the specific sedimentary horizons after deposition remains speculative. However, we show that the majority of sedimentary archaeal tetraether membrane lipids were of allochthonous origin and not produced in situ. Slow post-burial growth under energy-limited conditions would explain why the downcore distribution of these dominant archaeal groups still indirectly reflect changes in the paleodepositional environment that prevailed during the analyzed marine isotope stages. In addition, archaea seeded from the overlying water column such as Thaumarchaeota and group II and III Euryarchaeota, which were likely not have been able to subsist after burial, were identified from a lower abundance of preserved sedimentary DNA signatures, and represented direct markers of paleoenvironmental changes in the Red Sea spanning the last six marine isotope stages.
CitationMore, K. D., Wuchter, C., Irigoien, X., Tierney, J. E., Giosan, L., Grice, K., & Coolen, M. J. L. (2020). Subseafloor Archaea reflect 139 kyrs of paleodepositional changes in the northern Red Sea. Geobiology, 19(2), 162–172. doi:10.1111/gbi.12421
SponsorsThis work was primarily supported by KAUST-WHOI Special Academic Partnership Program OCRF-SP-WHOI-2013 (grants 7000000463 to XI and 7000000464 to MJLC). We kindly thank Mary Carman at WHOI for generating the δ18O foraminifera record and selecting foraminifera tests for radiocarbon dating. We thank the co-chiefs, scientific participants, captain, and crew of the RV Aegaeo for their assistance in the recovery of the core. We also thank the Curtin Office for Research and Development (ORD) for funding a PhD stipend to K.D.M.