‘Bleaching’ of Photosymbionts in Planktic Foraminifera During the Middle Eocene Climatic Optimum

2014 ◽  
Vol 13 ◽  
pp. 141-141
Author(s):  
Kirsty M. Edgar ◽  
Stephen M. Bohaty ◽  
Samantha J. Gibbs ◽  
Philip F. Sexton ◽  
Richard D. Norris ◽  
...  
Keyword(s):  
Middle Eocene ◽  
Planktic Foraminifera ◽  
Climatic Optimum

scholarly journals Symbiont 'bleaching' in planktic foraminifera during the Middle Eocene Climatic Optimum

Geology ◽  
2012 ◽  
Vol 41 (1) ◽  
pp. 15-18 ◽  
Author(s):  
K. M. Edgar ◽  
S. M. Bohaty ◽  
S. J. Gibbs ◽  
P. F. Sexton ◽  
R. D. Norris ◽  
...  
Keyword(s):  
Middle Eocene ◽  
Planktic Foraminifera ◽  
Climatic Optimum

scholarly journals New composite bio- and isotope stratigraphies spanning the Middle Eocene Climatic Optimum at tropical ODP Site 865 in the Pacific Ocean

2020 ◽  
Vol 39 (2) ◽  
pp. 117-138
Author(s):  
Kirsty M. Edgar ◽  
Steven M. Bohaty ◽  
Helen K. Coxall ◽  
Paul R. Bown ◽  
Sietske J. Batenburg ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Middle Eocene ◽  
Calcareous Nannofossils ◽  
Ocean Drilling Program ◽  
Planktic Foraminifera ◽  
The Pacific ◽  
Composite Section ◽  
Study Interval ◽  
Climatic Optimum ◽  
Calcareous Microfossils

Abstract. The Middle Eocene Climatic Optimum (MECO) at ca. 40 Ma is one of the largest of the transient Eocene global warming events. However, it is relatively poorly known from tropical settings since few sites span the entirety of the MECO event and/or host calcareous microfossils, which are the dominant proxy carrier for palaeoceanographic reconstructions. Ocean Drilling Program (ODP) Pacific Ocean Site 865 in the low-latitude North Pacific (Allison Guyot) has the potential to provide a useful tropical MECO reference, but detailed stratigraphic and chronological constraints needed to evaluate its completeness were previously lacking. We have addressed this deficit by generating new high-resolution biostratigraphic, stable isotope, and X-ray fluorescence (XRF) records spanning the MECO interval (∼38.0–43.0 Ma) in two holes drilled at Site 865. XRF-derived strontium ∕ calcium (Sr∕Ca) and barium ∕ strontium (Ba∕Sr) ratios and Fe count records allow correlation between holes and reveal pronounced rhythmicity, enabling us to develop the first composite section for Holes 865B and 865C and a preliminary cyclostratigraphy for the MECO. Using this new framework, the sedimentary record is interpreted to be continuous across the event, as identified by a pronounced transient benthic foraminiferal δ18O shift of ∼0.8 ‰. Calcareous microfossil biostratigraphic events from widely used zonation schemes are recognized, with generally good agreement between the two holes, highlighting the robustness of the new composite section and allowing us to identify planktic foraminiferal Zones E10–E15 and calcareous nannofossil Zones NP15–18. However, discrepancies in the relative position and ordering of several primary and secondary bioevents with respect to published schemes are noted. Specifically, the stratigraphic highest occurrences of planktic foraminifera, Acarinina bullbrooki, Guembelitrioides nuttalli, and Morozovella aragonensis, and calcareous nannofossils, Chiasmolithus solitus and Sphenolithus furcatolithoides, and the lowest occurrence of Reticulofenestra reticulata all appear higher in the section than would be predicted relative to other bioevents. We also note conspicuous reworking of older microfossils (from planktic foraminiferal Zones E5–E9 and E13) into younger sediments (planktic foraminiferal Zones E14–15) within our study interval consistent with reworking above the MECO interval. Regardless of reworking, the high-quality XRF records enable decimetre-scale correlation between holes and highlight the potential of Site 865 for constraining tropical environmental and biotic changes, not just across the MECO but also throughout the Palaeocene and early-to-middle Eocene interval.

scholarly journals Harmful algae and export production collapse in the equatorial Atlantic during the zenith of Middle Eocene Climatic Optimum warmth

Geology ◽  
2019 ◽  
Vol 47 (3) ◽  
pp. 247-250 ◽  
Author(s):  
Margot J. Cramwinckel ◽  
Robin van der Ploeg ◽  
Peter K. Bijl ◽  
Francien Peterse ◽  
Steven M. Bohaty ◽  
...  
Keyword(s):  
Middle Eocene ◽  
Harmful Algae ◽  
Equatorial Atlantic ◽  
Export Production ◽  
Climatic Optimum

scholarly journals TAXONOMICAL CONSIDERATIONS, PHYLOGENY, PALEOGEOGRAPHY AND PALEOCLIMATOLOGY OF THE MIDDLE EOCENE (BARTONIAN) PLANKTIC FORAMINIFERA FROM JABAL HAFIT, AL AIN AREA, UNITED ARAB EMIRATES

2020 ◽  
Vol 4 (1) ◽  
pp. 10-20
Author(s):  
Haidar Salim Anan
Keyword(s):  
United Arab Emirates ◽  
Present Author ◽  
Middle Eocene ◽  
Planktic Foraminifera ◽  
Oman Mountains ◽  
Foraminiferal Species ◽  
Al Ain ◽  
Eastern Limb ◽  
First Time

The taxonomical consideration, probable phylogeny and stratigraphic significance of twenty-eight middle Eocene (Bartonian) planktic foraminiferal species from the eastern limb of Jabal Hafit, Al Ain area, United Arab Emirates (UAE), Northern Oman Mountains (NOM) are presented, and twenty one of them are illustrated. Identification of these twenty-eight species belonging to ten genera Globoturborotalia, Subbotina, Globigerinatheka, Inordinatosphaera, Orbulinoides, Hantkenina, Acarinina, Morozovelloides, Pseudohastigerina and Turborotalia has led to the recognition of three biostratigraphic zones, in ascending order: Morozovelloides lehneri PRZ (E11), Orbulinoides beckmanni TRZ (E12) and Morozovelloides crassata HOZ (E13). Eight out of the identified species are recorded, in this study, for the first time from Jabal Hafit: Globoturborotalia martini, Subbotina gortanii, S. jacksonensis, S. senni, Globigerinatheca barri, Acarinina praetopilensis, A. punctocarinata and Morozovelloides bandyi. The second or third record of three species from J. Hafit outside its original records are recently documented by the present author: Inordinatosphaera indica, Hantkenina australis and H. compressa. The paleontology, paleoclimatology and paleogeographic distribution of the identified taxa at Jabal Hafit and other Paleogene outcrops in the UAE and Tethys are presented and discussed. The identified fauna emphasis the wide geographic areas in the Tethys, from Atlantic to Indian-Pacific Oceans via Mediterranean.

Rise and fall of rotaliids in the Paleocene-Eocene: the influence of climate and trophic competition

2021 ◽  
Author(s):  
Andrea Benedetti ◽  
Cesare Andrea Papazzoni ◽  
Francesca Romana Bosellini
Keyword(s):  
Middle Eocene ◽  
Ecological Niches ◽  
Trophic Conditions ◽  
Significant Drop ◽  
Abrupt Decrease ◽  
Faunal Turnover ◽  
Number Of Species ◽  
Early Eocene Climatic Optimum ◽  
Climatic Optimum ◽  
Larger Foraminifers

<p>It is largely accepted that climate plays a pivotal role in the diversification of shallow-water communities, with special regards to larger foraminifera (LF), also because increase of surface water temperatures is often accompanied by change in trophic conditions. The shift from widespread eutrophic to oligotrophic conditions in shallow seas probably contributed to the LF differentiation during Paleocene-Eocene times. However, there are few recent attempts to quantify the changes in biodiversity and to correlate them with the global climatic events of the Paleogene. We concentrated our attention on the group of rotaliids, resilient taxa that partially survived after the mass extinction occurred at the end of the Cretaceous.</p><p>Our data show that their differentiation at genus level was very rapid, reaching its maximum already in the late Danian SB2 Zone. Specific diversification, instead, culminated in late Thanetian SB4 Zone. A second peak in specific diversity is recorded during the Cuisian (upper part of the Ypresian), then rotaliid diversity steadily declined, as long as other groups of larger foraminifers, especially <em>Alveolina </em>and <em>Nummulites</em>, became more competitive and proliferated with a large number of species up to the Bartonian SB17 Zone, when a significant drop in rotaliid biodiversity is recorded.</p><p>Differently to other taxonomic groups, i.e., alveolinids and nummulitids, for which a single genus during the whole Eocene generated numerous species, rotaliid genera are usually characterized by a low number of species, possibly due to the re-opening of ecological niches after the abrupt decrease of diversity that followed the PETM event. The competition with other K-strategist LF probably contributed to the decline of rotaliids in the middle Eocene up to the MECO event, where a last dramatic drop is recorded.</p><p>The major changes appear strictly linked to warming events such as the Late Danian Event (LDE, starting of the generic diversification of rotaliids), Paleocene Eocene Termal Maximum (PETM, faunal turnover followed by abrupt decrease in both generic and specific diversity), Early Eocene Climatic Optimum (EECO, increase in number of K-strategists under widespread oligotrophic conditions) and Middle Eocene Climatic Optimum (MECO, ultimate drop in diversity and competition with other larger foraminifers).</p><p>This study was funded by the Italian Ministry of Education and Research (MIUR), funds PRIN 2017: project “Biota resilience to global change: biomineralization of planktic and benthic calcifiers in the past, present and future” (prot. 2017RX9XXY).</p>

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