scholarly journals Environmental changes during the Paleocene–Eocene Thermal Maximum in Spitsbergen as reflected by benthic foraminifera

2013 ◽  
Vol 32 (1) ◽  
pp. 19737 ◽  
Author(s):  
Jenö Nagy ◽  
David Jargvoll ◽  
Henning Dypvik ◽  
Malte Jochmann ◽  
Lars Riber
Keyword(s):  
Benthic Foraminifera ◽  
Environmental Changes ◽  
Thermal Maximum

The propagule method as a tool to study assemblage dynamics in benthic foraminifera: An example with pH variations

2021 ◽  
Author(s):  
Anna E. Weinmann ◽  
Susan T. Goldstein ◽  
Maria V. Triantaphyllou ◽  
Martin R. Langer
Keyword(s):  
Shallow Water ◽  
Benthic Foraminifera ◽  
Environmental Changes ◽  
Ph Gradients ◽  
Local Conditions ◽  
Recovery Mechanisms ◽  
Decreasing Ph ◽  
Set Up ◽  
Ph Variations ◽  
Insight Into

<p>Benthic foraminifera are important indicators for ecological studies. The assemblage composition of local communities can be used to analyze influences of environmental variables such as temperature, salinity, pH, and others. In recent years, the experimental propagule method has emerged as an effective tool to evaluate the influence of these variables on assemblage dynamics of benthic foraminifera. Propagules (tiny juveniles) of benthic foraminifera are widespread and can survive outside of a species’ natural distribution range. Their ability to become dormant and be re-activated once local conditions become suitable, is an important driver behind the capacity of foraminiferal assemblages to react quickly to environmental changes. In the laboratory, the propagules are first separated from the coarser fractions by sieving and then cultured under different conditions.</p><p>In the present study, we analyzed the effect of ocean pH on the composition of shallow-water assemblages from Corfu Island (Greece). Like other calcifying organisms, assemblages of foraminifera are susceptible to pH variations and have revealed compositional shifts along natural or experimental pH gradients. Our experimental set-up included four pH treatments between 6.5 and 8.5 at constant temperature and salinity (22°C and 38 ppt) for 5 weeks.</p><p>At the conclusion of the cultivation experiment, we found high numbers of grown specimens (825–1564 per replicate) and a high survivability rate throughout all treatments (78–87%). Higher pH (7.8 and 8.5) resulted in assemblages that were dominated by monothalamous and porcelaneous species, whereas lower pH (6.5 and 7.2) lead to a reduction in porcelaneous and an increase in agglutinated species. Several taxa showed significant positive or negative correlations with decreasing pH values.</p><p>Our results are congruent with previous findings that reported compositional shifts from calcareous to agglutinated taxa with decreasing pH (both from culture and field observations). Our study also indicates that the activation of propagules is an important mechanism behind assemblage dynamics in shallow-water foraminifera. As such, it offers an improved insight into potential resilience and recovery mechanisms of foraminiferal assemblages with regard to local or seasonal pH variations as well as ongoing ocean acidification.</p>

Carbon and nitrogen budgets and respiration rates of selected foraminifera of the Gullmar Fjord in Sweden

2021 ◽  
Author(s):  
Julia Wukovits ◽  
Nicolaas Glock ◽  
Johanna Nachbagauer ◽  
Petra Heinz ◽  
Wolfgang Wanek ◽  
...  
Keyword(s):  
Benthic Foraminifera ◽  
Environmental Changes ◽  
Microscopy Imaging ◽  
Test Volume ◽  
Nitrogen Budgets ◽  
Carbon And Nitrogen ◽  
Respiration Rates ◽  
Feeding Experiments ◽  
Nitrogen Intake ◽  
Oxygen Concentrations

<p>Benthic foraminifera are highly abundant, ubiquitous marine protists, with many species feeding on microalgae or phytodetritus. Knowledge about carbon and nitrogen budgets and metabolic activities of benthic foraminifera can help to increase our understanding about their ecology and their role in aquatic biogeochemistry at the sediment-water interface. This can further increase their application as proxies for environmental changes. Shifts in the benthic foraminiferal communities of the Swedish Gullmars Fjord document the shift from well oxygenated bottom waters to seasonal hypoxia at its deepest location the Alsbäck Deep (125 m), during the last century.</p><p>So far there are only investigations available relating foraminiferal community composition with increased primary productivity and resulting hypoxia in this Fjord. In contrast, studies about the species-specific feeding ecology or food derived foraminiferal carbon and nitrogen fluxes are scarce.</p><p>Therefore, laboratory feeding experiments and respiration rate measurements were carried out with <em>Bulimina marginata</em>, <em>Cassidulina laevigata</em> and <em>Globobulima turgida</em>, abundant foraminifera in such environments, collected in August 2017.</p><p>Experiments were conducted to evaluate the carbon and nitrogen intake and turnover of dual (<sup>13</sup>C and <sup>15</sup>N) isotope labelled <em>Phaeodactylum tricornutum</em> detritus; detritus of a common diatom in the Gullmar Fjord. For the feeding experiments, foraminifera were incubated at 9.1°C in the dark, in sterile filtered seawater at ambient oxygen concentrations. The foraminifera were fed for a period of 24 hours and subsequently incubated without food for another 24 hours. After each incubation cycle, foraminiferal respiration rates were measured. The individuals were analyzed via Elemental Analyzer-Isotope Ratio Mass Spectroscopy to evaluate <sup>13</sup>C/<sup>12</sup>C and <sup>15</sup>N/<sup>14</sup>N ratios and their bulk content of organic carbon and nitrogen.</p><p>Additionally, we present carbon and nitrogen to volume ratios for the foraminifera <em>B. marginata</em>, <em>C. laevigata</em>, <em>G. turgida</em>, <em>G. auriculata</em> and <em>Nonionella turgida</em>, as derived from elemental analysis and light microscopy imaging.</p><p>The results show, that <em>B. marginata</em>, an opportunistic species associated with high fluxes of organic matter, had the highest rate of specific carbon and nitrogen intake and turnover. <em>Cassidulina laevigata</em>, a species that co-occurs with fresh phytodetritus and does not tolerate very low oxygen concentrations, showed lower carbon and nitrogen intake rates. <em>Globobulima turgida</em>, a denitrifying infaunal species that thrives under hypoxia, showed the lowest specific carbon and nitrogen intake and turnover rates. Respiration rates of all species did not depend on incubation with or without a food source. The foraminifera showed similar carbon and nitrogen densities per test volume across all species.</p><p>Overall this study helps to improve the knowledge on the nutritional ecology of the investigated species, demonstrating the close relation between feeding/metabolic rates and their environmental niche and highlighting the need to introduce foraminiferal data in future marine carbon and nitrogen flux models.</p>

Stratigraphic and sedimentological aspects of the worldwide distribution of Apectodinium in Paleocene/Eocene Thermal Maximum deposits

2021 ◽  
pp. SP511-2020-46
Author(s):  
Christopher N. Denison
Keyword(s):  
Global Warming ◽  
Sea Level ◽  
Environmental Changes ◽  
Calcareous Nannofossil ◽  
Shallow Marine ◽  
Worldwide Distribution ◽  
Carbon Isotope Excursion ◽  
Thermal Maximum ◽  
Taxonomic Changes ◽  
Data Gap

AbstractThe Paleocene/Eocene Thermal Maximum (PETM) is characterized by pronounced global warming and associated environmental changes. In the more-or-less two decades since prior regional syntheses of Apectodinium distribution at the PETM, extensive biological and geochemical datasets have elucidated the effect of rising world temperatures on climate and the biome. A Carbon Isotope Excursion (CIE) that marks the Paleocene/Eocene Boundary (PEB) is associated with an acme of marine dinocysts of the genus Apectodinium in many locations. Distinctive foraminiferal and calcareous nannofossil populations may also be present.For this up-dated, dinocyst-oriented view of the PETM, data from worldwide locations have been evaluated with an emphasis on stratigraphic and sedimentological context. What has emerged is that a change in lithology is common, often to a distinctive siltstone or claystone unit, which contrasts with underlying and overlying lithotypes. This change, present in shallow marine/coastal settings and in deepwater turbidite deposits, is attributed to radical modifications of precipitation and erosional processes. An abrupt boundary carries the implication that some time (of unknowable duration) is potentially missing, which then requires caution in the interpretation of the pacing of events in relation to that boundary. In most instances an ‘abrupt’ or ‘rapid’ CIE onset can be attributed to a data gap at a hiatus, particularly in shallow shelf settings where transgression resulted from sea-level rise associated with the PETM. Truly gradational lower boundaries of the PETM interval are quite unusual, and if present, are poorly known so far. Gradational upper boundaries are more common, but erosional upper boundaries have been reported.Taxonomic changes have been made to clarify identification issues that have adversely impacted some biostratigraphic interpretations. Apectodinium hyperacanthum has been retained in Wetzeliella, its original genus. The majority of specimens previously assigned to Apectodinium hyperacanthum or Wetzeliella (Apectodinium) hyperacanthum have been re-assigned to an informal species, Apectodinium sp. 1. Dracodinium astra has been retained in its original genus as Wetzeliella astra, and is emended.

scholarly journals The impact of African aridity on the isotopic signature of Atlantic deep waters across the Middle Pleistocene Transition

2012 ◽  
Vol 77 (1) ◽  
pp. 182-191 ◽  
Author(s):  
Bruno Malaizé ◽  
Elsa Jullien ◽  
Amandine Tisserand ◽  
Charlotte Skonieczny ◽  
E. Francis Grousset ◽  
...  
Keyword(s):  
Deep Water ◽  
Benthic Foraminifera ◽  
Environmental Changes ◽  
Phase Relationship ◽  
Isotopic Signature ◽  
Middle Pleistocene ◽  
Time Interval ◽  
Deep Waters ◽  
Time Period ◽  
The Impact

A high resolution analysis of benthic foraminifera as well as of aeolian terrigenous proxies extracted from a 37 m-long marine core located off the Mauritanian margin spanning the last ~ 1.2 Ma, documents the possible link between major continental environmental changes with a shift in the isotopic signature of deep waters around 1.0–0.9 Ma, within the so-called Mid-Pleistocene Transition (MPT) time period. The increase in the oxygen isotopic composition of deep waters, as seen through the benthic foraminifera δ18O values, is consistent with the growth of larger ice sheets known to have occurred during this transition. Deep-water mass δ13C changes, also estimated from benthic foraminifera, show a strong depletion for the same time interval. This drastic change in δ13C values is concomitant with a worldwide 0.3‰ decrease observed in the major deep oceanic waters for the MPT time period. The phase relationship between aeolian terrigeneous signal increase and this δ13C decrease in our record, as well as in other paleorecords, supports the hypothesis of a global aridification amongst others processes to explain the deep-water masses isotopic signature changes during the MPT. In any case, the isotopic shifts imply major changes in the end-member δ18O and δ13C values of deep waters.

Environmental changes during the Cretaceous-Paleogene mass extinction and Paleocene-Eocene Thermal Maximum: Implications for the Anthropocene

2018 ◽  
Vol 56 ◽  
pp. 69-89 ◽  
Author(s):  
Gerta Keller ◽  
Paula Mateo ◽  
Jahnavi Punekar ◽  
Hassan Khozyem ◽  
Brian Gertsch ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Environmental Changes ◽  
Thermal Maximum

Stable isotope and chemical stratigraphy of the Eocene Tambaba Formation: correlations with the Palaeocene-Eocene Thermal Maximum event

2021 ◽  
pp. SP507-2020-35
Author(s):  
José Diego Dias Veras ◽  
João Adauto de Souza Neto ◽  
Alcides Nóbrega Sial ◽  
Valderez Pinto Ferreira ◽  
Virgínio Henrique de Miranda Lopes Neumann
Keyword(s):  
Trace Elements ◽  
Upper Cretaceous ◽  
Environmental Changes ◽  
Major And Trace Elements ◽  
Northeastern Brazil ◽  
Depositional Sequence ◽  
Thermal Maximum ◽  
Carbonate Sequence ◽  
Environmental Responses ◽  
The Relationship

AbstractThe Paraíba Basin has a well-defined carbonate depositional sequence from the Upper Cretaceous (Campanian) to the Eocene. The carbonate sequence consists of Itamaracá, Gramame, Maria Farinha and Tambaba formations, which mainly contain calcareous sandstones and carbonates with siliciclastics, limestone-marl alternations, limestones and marls, and limestones, respectively. The Tambaba Formation is composed of reef limestones, ranging from fossil- and ichnofossil-rich calcilutite to calcarenite. We investigated the rocks of this unit located on a representative geological section in the Tambaba Beach, Northeastern Brazil, in order to elucidated the environmental responses recorded in geochemical proxies (C and O isotopic composition, and distribution of major and trace elements). The δ13C and δ18O values ranged from 1.0 to 2.7‰ VPDB and from -1.3 to 1.1‰ VPDB, respectively. The interpretation of this response suggests environmental changes, such as an increase or decrease in bioproductivity from the organisms that build these reef limestones. These changes are also recorded in the behavior of the major and trace elements, for example, the relationship among SiO2, Al2O3, MgO and CaO, characterizing two different cycles during the deposition of these limestones: the first one characterized by a predominantly carbonate deposition, and the second one presenting a pulse of siliciclastic content. In addition, the palaeotemperature values (9 to 15°C, obtained by δ18O data) found together with chemostratigraphic profiles of previous studies (e.g. δ13C, CaO, MgO, SiO2, Al2O3) indicate that the reef limestones of the Tambaba Formation were probably deposited about 5 Ma after the Palaeocene-Eocene Thermal Maximum event.

scholarly journals Variability in climate and productivity during the Paleocene–Eocene Thermal Maximum in the western Tethys (Forada section)

2016 ◽  
Vol 12 (2) ◽  
pp. 213-240 ◽  
Author(s):  
L. Giusberti ◽  
F. Boscolo Galazzo ◽  
E. Thomas
Keyword(s):  
Environmental Changes ◽  
Hydrological Cycle ◽  
Species Turnover ◽  
Average Chain Length ◽  
Primary Role ◽  
Higher Plant ◽  
Foraminiferal Assemblage ◽  
Western Tethys ◽  
Thermal Maximum ◽  
Biomarker Data

Abstract. The Forada section (northeastern Italy) provides a continuous, expanded deep-sea record of the Paleocene–Eocene Thermal Maximum (PETM) in the central-western Tethys. We combine a new, high-resolution, benthic foraminiferal assemblage record with published calcareous plankton, mineralogical and biomarker data to document climatic and environmental changes across the PETM, highlighting the benthic foraminiferal extinction event (BEE). The onset of the PETM, occurring  ∼ 30 kyr after a precursor event, is marked by a thin, black, barren clay layer, possibly representing a brief pulse of anoxia and carbonate dissolution. The BEE occurred within the 10 cm interval including this layer. During the first 3.5 kyr of the PETM, several agglutinated recolonizing taxa show rapid species turnover, indicating a highly unstable, CaCO3-corrosive environment. Calcareous taxa reappeared after this interval, and the next  ∼9 kyr were characterized by rapid alternation of peaks in abundance of various calcareous and agglutinated recolonizers. These observations suggest that synergistic stressors, including deepwater CaCO3 corrosiveness, low oxygenation, and high environmental instability caused the extinction. Combined faunal and biomarker data (BIT index, higher plant n-alkane average chain length) and the high abundance of the mineral chlorite suggest that erosion and weathering increased strongly at the onset of the PETM, due to an overall wet climate with invigorated hydrological cycle, which led to storm flood events carrying massive sediment discharge into the Belluno Basin. This interval was followed by the core of the PETM, characterized by four precessionally paced cycles in CaCO3 %, hematite %, δ13C, abundant occurrence of opportunistic benthic foraminiferal taxa, and calcareous nannofossil and planktonic foraminiferal taxa typical of high-productivity environments, radiolarians, and lower δDn-alkanes. We interpret these cycles as reflecting alternation between an overall arid climate, characterized by strong winds and intense upwelling, and an overall humid climate, with abundant rains and high sediment delivery (including refractory organic carbon) from land. Precessionally paced marl–limestone couplets occur throughout the recovery interval of the carbon isotope excursion (CIE) and up to 10 m above it, suggesting that these wet–dry cycles persisted, though at declining intensity, after the peak PETM. Enhanced climate extremes at mid-latitudes might have been a direct response to the massive CO2 input in the ocean atmosphere system at the Paleocene–Eocene transition, and may have had a primary role in restoring the Earth system to steady state.

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