Exploring photosymbiotic ecology of planktic foraminifers from chamber-by-chamber isotopic history of individual foraminifers

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doi: 10.1017/pab.2014.7
Author(s): Takagi, Haruka; Moriya, Kazuyoshi; Ishimura, Toyoho; Suzuki, Atsushi; Kawahata, Hodaka; Hirano, Hiromichi
Author Affiliation(s): Primary:
Waseda University, Graduate School of Creative Science and Engineering, Tokyo, Japan
Other:
Geological Survey of Japan, Japan
University of Tokyo, Japan
Volume Title: Paleobiology
Source: Paleobiology, 41(1), p.108-121. Publisher: Paleontological Society, Lawrence, KS, United States. ISSN: 0094-8373 CODEN: PALBBM
Note: In English. 51 refs.; illus., incl. 3 tables, sketch map
Summary: Evolution of photosymbiotic ecology is an important adaptation for planktic foraminifers that enhances the ecological advantage of living in oligotrophic oceans. Therefore, detecting photosymbiotic ecology in fossil species is one of the keys to understanding the paleobiodiversity dynamics of planktic foraminifers. Because foraminiferal tests record the ontogenetic history of ecological information in geochemical signatures, analyzing individual geochemical profiles with growth can reveal a species' ecology. This study examined chamber-by-chamber stable isotopes (δ13C and δ18O) of foraminiferal individuals to identify photosymbiotic signals. We observed an ontogenetic δ13C increase of up to 2.4 ppm, accompanied by relatively stable, negative δ18O, in the symbiotic species Globigerinoides conglobatus and Globigerinoides sacculifer. In contrast, δ13C and δ18O showed significant positive correlation during ontogeny in the asymbiotic species Globorotalia truncatulinoides. These two ecological groups produce contrasting isotopic profiles, thereby allowing us to use our ontogenetic isotopic analyses of individual specimens to identify algal photosymbiosis in fossil foraminifers. The chamber-by-chamber isotope analyses with individual ontogeny have great advantages in analyzing rare species because only one individual is required to describe ontogenetic isotopic history. In addition to photosymbiotic identification, our methods hold great potential to provide new insight into species paleoecological studies such as the ontogenetic history of calcification depth.
Year of Publication: 2015
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 02 Geochemistry; 10 Paleontology, Invertebrate; C-13/C-12; Carbon; Cenozoic; Chemical composition; Electron microscopy data; Expedition 330; Foraminifera; Globigerinacea; Globigerinidae; Globigerinoides; Globorotalia; Globorotalia truncatulinoides; Globorotaliidae; Holocene; IODP Site U1372; Integrated Ocean Drilling Program; Invertebrata; Isotope ratios; Isotopes; Microfossils; Morphology; O-18/O-16; Ontogeny; Oxygen; Pacific Ocean; Paleoecology; Planktonic taxa; Protista; Quaternary; Rotaliina; SEM data; South Pacific; Stable isotopes; Symbiosis; Tests
Coordinates: S262936 S262936 W1744345 W1744345
Record ID: 2015078934
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, The Paleontological Society, Reference includes data from GeoScienceWorld, Alexandria, VA, United States