Succession of bacterial community structure and potential significance along a sediment core from site U1433 of IODP Expedition 349, South China Sea

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doi: 10.1016/j.margeo.2017.06.010
Author(s): Zhang Yao; Liang Pan; Xie Xiabing; Dai Xiaofeng; Liu Haodong; Zhang Chuanlun; Kao Shuhji; Jiao Nianzhi
Author Affiliation(s): Primary:
Xiamen University, State Key Laboratory of Marine Environmental Sciences, Xiamen, China
Other:
Tongji University, China
Volume Title: Evolution of the deep South China Sea; Integrated IODP Expedition 349 results
Volume Author(s): Liu Zhifei, editor; Li Chunfeng; Kulhanek, Denise
Source: Evolution of the deep South China Sea; Integrated IODP Expedition 349 results, edited by Liu Zhifei, Li Chunfeng and Denise Kulhanek. Marine Geology, Vol.394, p.125-132. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0025-3227 CODEN: MAGEA6
Note: In English. 65 refs.; illus., incl. 1 table
Summary: To evaluate the potential impact of geological processes and depositional history on shaping the subsurface biosphere, the bacterial community structures in a sediment core of the South China Sea was investigated by molecular approaches that target 16S rRNA gene fragments. Samples were obtained from different lithologic intervals at site U1433 during the International Ocean Discovery Program (IODP) Expedition 349. Bacterial abundance decreased rapidly with depth, with nearly three orders of magnitude decline within the first 100 m below seafloor (mbsf). Community diversity displayed a similar decreasing pattern, yet, a slight increase in diversity emerged in the early to middle Miocene. Such excursion might reflect enhanced cell activity in response to increasing temperature due to a steep geothermal gradient. Non-metric multidimensional scaling ordination revealed that the bacterial communities along the sediment core represent four clusters based on depth and geological time. There were distinct bacterial community shifts among clusters at 4.50-98.93 mbsf (Pleistocene), 108.15-273.20 mbsf (Pleistocene), 296.09-709.13 mbsf (Pliocene and late Miocene), and 732.10-789.91 mbsf (early to middle Miocene). Classification analysis revealed a striking pattern: the relative abundance of microorganisms affiliated with Gammaproteobacteria, Actinobacteria, and Cyanobacteria overall consistently decreased with depth, whereas those affiliated with Chloroflexi, candidate division OP9, candidate phylum BHI80-139, and Nitrospirae increased; these findings correspond to different clusters. Total organic carbon content and ratio of total organic carbon: total nitrogen, along with pore water phosphate concentration and salinity, were the statistically most significant variables that explained the bacterial community cluster pattern, which indicates potential linkages of bacterial communities to changes in quality and quantity of buried organic matter over geological time scales. Geographic isolation across depth was more important than environmental condition and geological age for the development of unique community structure in marine deep biosphere, although environmental variables partially shaped bacterial community composition.
Year of Publication: 2017
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 24 Surficial Geology, Quaternary Geology; Bacteria; Biostratigraphy; Cenozoic; Communities; Cores; DNA; Expedition 349; Genetics; IODP Site U1433; International Ocean Discovery Program; Marine sediments; North Pacific; Northwest Pacific; Nucleic acids; Pacific Ocean; Paleoecology; Pleistocene; Quaternary; RNA; Sediments; South China Sea; Statistical analysis; Tertiary; West Pacific
Coordinates: N125508 N125508 E1150251 E1150250
Record ID: 2018009029
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands