Benthic foraminiferal turnover across the Dan-C2 event in the eastern South Atlantic Ocean (ODP Site 1262)

G.J.A.R. and L.A. acknowledge funding from projects CGL2017-84693-R and PID2019-105537RB-I00 (Spanish Ministry of Science and Innovation and FEDER funds), and from Consolidated Group E05 (Government of Aragon/Fondo Europeo de Desarrollo Regional). E.T. recognises partial funding by NSF_OCE 1536611. G.J.A.R thanks the Consejo Nacional de Ciencia y Tecnología (Conacyt, México) for her predoctoral fellowship. J.S.K.B. and K.L. acknowledge funding from the Natural Environment Research Council (NERC) Isotope Geosciences Facility at the British Geological Survey (IP-1581–1115) and D.N.S. support from the Royal Society via Wolfson Merit award. This research used samples provided by the Ocean Drilling Program (ODP), sponsored by the U.S. National Science Foundation (NSF) and participating countries under management of Joint Oceanographic Institutions (JOI), Inc.The Paleogene was punctuated by perturbations of the global carbon cycle, many associated with transient global warming events (hyperthermals). The Dan-C2 event (~160 kyr after Cretaceous/Paleogene boundary; K/Pg) was the oldest of these eccentricity-linked carbon cycle disturbances (ELCD). In contrast to other hyperthermals, the Dan-C2 event was not characterised by bottom water warming, and surface water warming probably was not global. Benthic foraminiferal assemblages across Dan-C2 at SE Atlantic Ocean Drilling Program (ODP) Site 1262 are diverse and strongly dominated by calcareous species. Epifaunal and infaunal morphogroups are equally abundant, suggesting meso-oligotrophic seafloor conditions. Assemblages decreased in diversity gradually before Dan-C2, and Nuttallides truempyi decreased in relative abundance while Stensioeina beccariiformis and the agglutinant Spiroplectammina spectabilis increased, suggesting enhanced food supply to the seafloor. Benthic foraminifera were not highly affected by the Dan-C2 event. An increase in relative abundance of the opportunistic species Bulimina kugleri and Seabrookia cretacea after Dan-C2 points to a change in the type of organic matter arriving at the seafloor. These changes may have been caused by ongoing environmental and/or evolutionary instability following K/Pg mass extinction of oceanic plankton. Variability in composition of pelagic ecosystems, thus the type and/or amount of food arriving at the seafloor, may have been caused by the gradual recovery of pelagic ecosystems after that extinction, possibly affected by warming and pH changes due to Deccan volcanism.PostprintPeer reviewe

Benthic foraminiferal turnover across the Dan-C2 event in the eastern South Atlantic Ocean (ODP Site 1262)

G.J.A.R. and L.A. acknowledge funding from projects CGL2017-84693-R and PID2019-105537RB-I00 (Spanish Ministry of Science and Innovation and FEDER funds), and from Consolidated Group E05 (Government of Aragon/Fondo Europeo de Desarrollo Regional). E.T. recognises partial funding by NSF_OCE 1536611. G.J.A.R thanks the Consejo Nacional de Ciencia y Tecnología (Conacyt, México) for her predoctoral fellowship. J.S.K.B. and K.L. acknowledge funding from the Natural Environment Research Council (NERC) Isotope Geosciences Facility at the British Geological Survey (IP-1581–1115) and D.N.S. support from the Royal Society via Wolfson Merit award. This research used samples provided by the Ocean Drilling Program (ODP), sponsored by the U.S. National Science Foundation (NSF) and participating countries under management of Joint Oceanographic Institutions (JOI), Inc.The Paleogene was punctuated by perturbations of the global carbon cycle, many associated with transient global warming events (hyperthermals). The Dan-C2 event (~160 kyr after Cretaceous/Paleogene boundary; K/Pg) was the oldest of these eccentricity-linked carbon cycle disturbances (ELCD). In contrast to other hyperthermals, the Dan-C2 event was not characterised by bottom water warming, and surface water warming probably was not global. Benthic foraminiferal assemblages across Dan-C2 at SE Atlantic Ocean Drilling Program (ODP) Site 1262 are diverse and strongly dominated by calcareous species. Epifaunal and infaunal morphogroups are equally abundant, suggesting meso-oligotrophic seafloor conditions. Assemblages decreased in diversity gradually before Dan-C2, and Nuttallides truempyi decreased in relative abundance while Stensioeina beccariiformis and the agglutinant Spiroplectammina spectabilis increased, suggesting enhanced food supply to the seafloor. Benthic foraminifera were not highly affected by the Dan-C2 event. An increase in relative abundance of the opportunistic species Bulimina kugleri and Seabrookia cretacea after Dan-C2 points to a change in the type of organic matter arriving at the seafloor. These changes may have been caused by ongoing environmental and/or evolutionary instability following K/Pg mass extinction of oceanic plankton. Variability in composition of pelagic ecosystems, thus the type and/or amount of food arriving at the seafloor, may have been caused by the gradual recovery of pelagic ecosystems after that extinction, possibly affected by warming and pH changes due to Deccan volcanism.PostprintPeer reviewe

Early Eocene deep-sea benthic foraminiferal faunas: Recovery from the Paleocene Eocene Thermal Maximum extinction in a greenhouse world

<div><p>The early Eocene greenhouse world was marked by multiple transient hyperthermal events. The most extreme was the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma), linked to the extinction of the globally recognised deep-sea benthic foraminiferal Velasco fauna, which led to the development of early Eocene assemblages. This turnover has been studied at high resolution, but faunal development into the later early Eocene is poorly documented. There is no widely accepted early Eocene equivalent of the Late Cretaceous-Paleocene Velasco fauna, mainly due to the use of different taxonomic concepts. We compiled Ypresian benthic foraminiferal data from 17 middle bathyal-lower abyssal ocean drilling sites in the Pacific, Atlantic and Indian Oceans, in order to characterise early Eocene deep-sea faunas by comparing assemblages across space, paleodepth and time. <i>Nuttallides truempyi</i>, <i>Oridorsalis umbonatus</i>, <i>Bulimina trinitatensis</i>, the <i>Bulimina simplex</i> group, the <i>Anomalinoides spissiformis</i> group, pleurostomellids, uniserial lagenids, stilostomellids and lenticulinids were ubiquitous during the early Eocene (lower-middle Ypresian). <i>Aragonia aragonensis</i>, the <i>Globocassidulina subglobosa</i> group, the <i>Cibicidoides eocaenus</i> group and polymorphinids became ubiquitous during the middle Ypresian. The most abundant early Ypresian taxa were tolerant to stressed or disturbed environments, either by opportunistic behavior (<i>Quadrimorphina profunda</i>, <i>Tappanina selmensis</i>, <i>Siphogenerinoides brevispinosa</i>) and/or the ability to calcify in carbonate-corrosive waters (<i>N</i>. <i>truempyi</i>). <i>Nuttallides truempyi</i>, <i>T</i>. <i>selmensis</i> and other buliminids (<i>Bolivinoides</i> cf. <i>decoratus</i> group, <i>Bulimina virginiana</i>) were markedly abundant during the middle Ypresian. Contrary to the long-lived, highly diverse and equitable Velasco fauna, common and abundant taxa reflect highly perturbed assemblages through the earliest Ypresian, with lower diversity and equitability following the PETM extinction. In contrast, the middle Ypresian assemblages may indicate a recovering fauna, though to some extent persistently disturbed by the lower-amplitude Eocene hyperthermals (e.g., Eocene Thermal Maximum 2 and 3). We propose the name ‘Walvis Ridge fauna’ for future reference to these Ypresian deep-sea benthic foraminiferal assemblages.</p></div

Non-metric multidimensional scaling plots (stress = 0.132) performed using middle Ypresian species.

<p>The difference among the middle Ypresian species based on their relative abundance is shown according to coordinates 1–2 (A) and coordinates 2–3 (B). The abundance of the species located outside the 95% confidence ellipse is significantly distinct (higher) in comparison with the species inside the ellipse. Common species are marked with black dots, and abundant/very abundant species are indicated with colored circles. The color of the circle represents the sites where such species are abundant. Color reference: light blue-SE Atlantic sites, dark blue-high latitude Atlantic sites, red-Indian site, grey-NA sites, and purple-seamount site. Abbreviations found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193167#pone.0193167.t005" target="_blank">Table 5</a>.</p

Location of ODP and DSDP sites reviewed in this study.

<p>Sites where benthic foraminifera are recorded across both Ypresian intervals (lower and middle) are indicated with stars, those encompassing only the lower Ypresian are marked with triangles, and those covering exclusively the middle Ypresian are shown with squares. Color reference: green-Pacific sites, blue-Atlantic sites, red-Indian site. Paleogeographic reconstruction of ~53 Ma from Hay et al., [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193167#pone.0193167.ref069" target="_blank">69</a>].</p

Paleobathymetry of ODP and DSDP sites.

<p>The circles represent the average of the depth range estimates, full data are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193167#pone.0193167.t001" target="_blank">Table 1</a>. Abbreviations: SO = Southern Ocean; U = upper; M = middle; L = lower.</p

SEM images of some abundant Ypresian (lower Eocene) species.

<p>All scale bars represent 100 μm, unless otherwise indicated. 1, <i>Seabrookia rugosa</i> (sample 1258-14-4, 44–46 cm): a) lateral, b) apertural. 2, <i>Aragonia aragonensis</i> (sample 550-29-1, 8–10 cm): a) apertural, b) lateral. 3, <i>Tappanina selmensis</i> (sample 1258-14-4, 14–16 cm). 4, <i>Bolivinoides decoratus</i> (sample 550-29-4, 15–17 cm). 5, <i>Bulimina elongata</i> (sample 550-29-1, 52–54 cm). 6, <i>Bulimina semicostata</i> (sample 1051-48-1, 37–39 cm). 7, <i>Bulimina virginiana</i> (sample 1051-48-2, 75–77 cm). 8, <i>Bulimina</i> sp. 1 (sample 1258-14-4, 14–16 cm). 9, <i>Bulimina</i> sp. 1 (sample 1258-14-4, 14–16 cm). 10, <i>Bulimina kugleri</i> (sample 550-30-1, 106.5–108 cm). 11, <i>Siphogenerinoides brevispinosa</i> (sample 1258-14-CC, 5–7 cm). 12, <i>Quadrimorphina profunda</i> (sample 401-13-2, 43–45 cm): umbilical. 13, <i>Quadrimorphina profunda</i> (sample 550-29-5, 126.5–129 cm): ventral. 14, <i>Abyssamina poagi</i> (sample 550-30-1, 106.5–108 cm): umbilical. 15, <i>Abyssamina poagi</i> (sample 401-13-3, 43–45 cm): apertural. 16, <i>Globocassidulina subglobosa</i> (sample 550-29-6, 57–59 cm). 17, <i>Epistominella exigua</i> (sample 401-13-4, 130–132 cm): a) ventral, b) dorsal. 18, <i>Nuttallides umbonifera</i> (sample 550-29-5, 15–17 cm): ventral. 19, <i>Nuttallides umbonifera</i> (sample 550-29-5, 15–17 cm): apertural. 20, <i>Nuttallides umbonifera</i> (sample 550-29-1, 8–10 cm): dorsal. 21, <i>Osangularia</i> sp. 1 (sample 550-29-5, 15–17 cm): dorsal. 22, <i>Osangularia</i> sp. 1 (sample 550-29-4, 65–67 cm): apertural. 23, <i>Osangularia</i> sp. 1 (sample 550-29-2, 53–55 cm): ventral. 24, <i>Cibicidoides praemundulus</i> (sample 865-10-2, 4–6 cm): a) umbilical, b) dorsal. 25, <i>Cibicidoides praemundulus</i> (sample 865-10-2, 4–6 cm): apertural. 26, <i>Cibicidoides proprius</i> (sample 401-13-4, 130–132 cm): a) dorsal, b) apertural, c) ventral. 27, <i>Gyroidinoides depressus</i> (sample 865-10-2, 60–62 cm): a) ventral, b) apertural, c) dorsal. 28, <i>Gyroidinoides planulatus</i> (sample 550-29-1, 52–54 cm): a) dorsal, b) apertural, c) ventral. 29, <i>Gyroidinoides complanata</i> (sample 401-13-4, 130–132 cm): a) dorsal, b) apertural, c) ventral.</p

Taxa included into supra-generic groups of benthic foraminifera, based on their main morphological characteristics.

<p>Taxa included into supra-generic groups of benthic foraminifera, based on their main morphological characteristics.</p

Informal taxonomic groups of similar taxa observed within the lower Eocene (lower and middle Ypresian) at ODP and DSDP sites analysed in this study.

<p>Informal taxonomic groups of similar taxa observed within the lower Eocene (lower and middle Ypresian) at ODP and DSDP sites analysed in this study.</p

Relative abundance of benthic foraminifera from ODP and DSDP sites across the lower Ypresian.

<p>Relative abundance of benthic foraminifera from ODP and DSDP sites across the lower Ypresian.</p