Symbiont "bleaching" in planktic Foraminifera during the middle Eocene climatic optimum

Online Access: Get full text
doi: 10.1130/G33388.1
Author(s): Edgar, K. M.; Bohaty, S. M.; Gibbs, S. J.; Sexton, P. F.; Norris, R. D.; Wilson, P. A.
Author Affiliation(s): Primary:
University of Southampton, National Oceanography Centre Southampton, Southampton, United Kingdom
Other:
Scripps Institution of Oceanography, United States
Volume Title: Geology (Boulder)
Source: Geology (Boulder), 41(1), p.15-18. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613 CODEN: GLGYBA
Note: In English. With GSA Data Repository Item 2013002. 34 refs.; illus.
Summary: Many genera of modern planktic foraminifera are adapted to nutrient-poor (oligotrophic) surface waters by hosting photosynthetic symbionts, but it is unknown how they will respond to future changes in ocean temperature and acidity. Here we show that ca. 40 Ma, some fossil photosymbiont-bearing planktic foraminifera were temporarily 'bleached' of their symbionts coincident with transient global warming during the Middle Eocene Climatic Optimum (MECO). At Ocean Drilling Program (ODP) Sites 748 and 1051 (Southern Ocean and mid-latitude North Atlantic, respectively), the typically positive relationship between the size of photosymbiont-bearing planktic foraminifer tests and their carbon isotope ratios (δ13C) was temporarily reduced for ∼100 k.y. during the peak of the MECO. At the same time, the typically photosymbiont-bearing planktic foraminifera Acarinina suffered transient reductions in test size and relative abundance, indicating ecological stress. The coincidence of minimum δ18O values and reduction in test size-δ13C gradients suggests a link between increased sea-surface temperatures and bleaching during the MECO, although changes in pH and nutrient availability may also have played a role. Our findings show that host-photosymbiont interactions are not constant through geological time, with implications for both the evolution of trophic strategies in marine plankton and the reliability of geochemical proxy records generated from symbiont-bearing planktic foraminifera.
Year of Publication: 2012
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Acarinina; Atlantic Ocean; Blake Nose; Blake Plateau; C-13/C-12; Carbon; Cenozoic; Eocene; Foraminifera; Indian Ocean; Invertebrata; Isotope ratios; Isotopes; Kerguelen Plateau; Leg 120; Leg 171B; Microfossils; Middle Eocene; Middle Eocene climatic optium; North Atlantic; O-18/O-16; ODP Site 1051; ODP Site 748; Ocean Drilling Program; Oxygen; Paleoclimatology; Paleoecology; Paleoenvironment; Paleogene; Paleotemperature; Planktonic taxa; Protista; Sea water; Stable isotopes; Symbiosis; Tertiary
Coordinates: S582627 S582627 E0785854 E0785853
N300311 N300311 W0762128 W0762128
Record ID: 2012101388
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States, Reference includes data supplied by the Geological Society of America