scholarly journals <i>Acarinina multicamerata</i> n. sp. (Foraminifera): a new marker for the Paleocene–Eocene thermal maximum

2008 ◽  
Vol 27 (1) ◽  
pp. 5-12 ◽  
Author(s):  
Elisa Guasti ◽  
Robert P. Speijer
Keyword(s):  
Open Ocean ◽  
Common Occurrence ◽  
Thermal Maximum ◽  
Group A ◽  
Surface Dwelling

Abstract. During the Paleocene–Eocene thermal maximum (PETM), low to mid-latitude planktic foraminiferal assemblages were characterized by blooms of the surface-dwelling Acarinina. Among this group a new ‘excursion taxon’ is identified, Acarinina multicamerata n. sp. Previously, this taxon was lumped together with Acarinina sibaiyaensis El-Naggar. Considering that A. sibaiyaensis already occurred prior to the hyperthermal event, both in open ocean and ocean margin deposits, it is proposed that these taxa are differentiated in order to avoid taxonomic and biostratigraphic ambiguities. Acarinina multicamerata n. sp. occurred exclusively during the PETM, hence this taxon represents an excellent biostrati-graphic marker of the PETM, while its common occurrence in various marine settings makes it an excellent marker of Subzone P5b or its new equivalent zone E1.

Calcareous nannoplankton ecology and community change across the Paleocene-Eocene Thermal Maximum

Paleobiology ◽  
10.1666/12050 ◽  
2013 ◽  
Vol 39 (4) ◽  
pp. 628-647 ◽  
Author(s):  
Leah J. Schneider ◽  
Timothy J. Bralower ◽  
Lee R. Kump ◽  
Mark E. Patzkowsky
Keyword(s):  
Nutrient Availability ◽  
Multivariate Analyses ◽  
Geochemical Modeling ◽  
Community Change ◽  
Open Ocean ◽  
Data Set ◽  
Long Term Effect ◽  
Term Change ◽  
Thermal Maximum

The Paleocene-Eocene Thermal Maximum (PETM; ca. 55.8 Ma) is thought to coincide with a profound but entirely transient change among nannoplankton communities throughout the ocean. Here we explore the ecology of nannoplankton during the PETM by using multivariate analyses of a global data set that is based upon the distribution of taxa in time and space. We use these results, coupled with stable isotope data and geochemical modeling, to reinterpret the ecology of key genera. The results of the multivariate analyses suggest that the community was perturbed significantly in coastal and high-latitudes sites compared to the open ocean, and the relative influence of temperature and nutrient availability on the assemblage varies regionally. The open ocean became more stratified and less productive during the PETM and the oligotrophic assemblage responded primarily to changes in nutrient availability. Alternatively, assemblages at the equator and in the Southern Ocean responded to temperature more than to nutrient reduction. In addition, the assemblage change at the PETM was not merely transient—there is evidence of adaptation and a long-term change in the nannoplankton community that persists after the PETM and results in the disappearance of a high-latitude assemblage. The long-term effect on communities caused by transient warming during the PETM has implications for modern-day climate change, suggesting similar permanent changes to nannoplankton community structure as the oceans warm.

Critical Thermal Maximum Temperatures in Australian Scincid Lizards: Their Ecological and Evolutionary Significance.

1980 ◽  
Vol 28 (1) ◽  
pp. 91 ◽  
Author(s):  
AE Greer
Keyword(s):  
Maximum Temperature ◽  
Evolutionary Significance ◽  
Thermal Barrier ◽  
Critical Thermal Maximum ◽  
Thermal Maximum ◽  
Surface Dwelling ◽  
Maximum Temperatures

The critical thermal maximum temperature (CTMAX) has now been determined for representatives of 16 of the 21 genera of scincid lizards in Australia. Taxa from the warm interior of the country generally have a mean CTMAX greater than 39.5�C regardless of their behaviour or habitat. Taxa from the cooler periphery of the continent fall into two groups based on their behaviour and habitat: diurnal, surface- dwelling forms generally have a mean CTMAX above 39.5�C whereas crepuscular to nocturnal. or cryptozoic to fossorial forms, have a mean CTMAX below 39.5�C. The skinks of the interior probably evolved from ancestors occupying habitats most similar to ones now occurring on the periphery. In these more equable habitats. diurnal surface-dwelling forms, with their high CTMAX, would have been preadapted to invade the habitats of the interior, whereas crepuscular to nocturnal. or cryptozoic to fossorial forms, with their low CTMAX, may have had to overcome a thermal barrier to enter these habitats. This may account in part for the paucity of crepuscular to nocturnal or cryptozoic to fossorial skink lineages in the interior. Unlike most other lizard families, most skinks do not pant when heat stressed. The reasons for this are unknown.

scholarly journals The critical thermal maximum of diving beetles (Coleoptera: Dytiscidae): a comparison of subterranean and surface-dwelling species.

2021 ◽  
pp. 100019
Author(s):  
Karl K. Jones ◽  
William F. Humphreys ◽  
Mattia Saccò ◽  
Terry Bertozzi ◽  
Andy D. Austin ◽  
...  
Keyword(s):  
Critical Thermal Maximum ◽  
Diving Beetles ◽  
Thermal Maximum ◽  
Surface Dwelling

scholarly journals Tropical Atlantic climate and ecosystem regime shifts during the Paleocene–Eocene Thermal Maximum

2018 ◽  
Vol 14 (1) ◽  
pp. 39-55 ◽  
Author(s):  
Joost Frieling ◽  
Gert-Jan Reichart ◽  
Jack J. Middelburg ◽  
Ursula Röhl ◽  
Thomas Westerhold ◽  
...  
Keyword(s):  
Heat Stress ◽  
Environmental Variability ◽  
Equatorial Atlantic ◽  
Ocean Drilling Program ◽  
Tropical Regions ◽  
Surface Ocean ◽  
Ocean Drilling ◽  
Carbon Isotope Excursion ◽  
Thermal Maximum ◽  
Surface Dwelling

Abstract. The Paleocene–Eocene Thermal Maximum (PETM, 56 Ma) was a phase of rapid global warming associated with massive carbon input into the ocean–atmosphere system from a 13C-depleted reservoir. Many midlatitude and high-latitude sections have been studied and document changes in salinity, hydrology and sedimentation, deoxygenation, biotic overturning, and migrations, but detailed records from tropical regions are lacking. Here, we study the PETM at Ocean Drilling Program (ODP) Site 959 in the equatorial Atlantic using a range of organic and inorganic proxies and couple these with dinoflagellate cyst (dinocyst) assemblage analysis. The PETM at Site 959 was previously found to be marked by a  ∼  3.8 ‰ negative carbon isotope excursion (CIE) and a  ∼  4 °C surface ocean warming from the uppermost Paleocene to peak PETM, of which  ∼  1 °C occurs before the onset of the CIE. We record upper Paleocene dinocyst assemblages that are similar to PETM assemblages as found in extratropical regions, confirming poleward migrations of ecosystems during the PETM. The early stages of the PETM are marked by a typical acme of the tropical genus Apectodinium, which reaches abundances of up to 95 %. Subsequently, dinocyst abundances diminish greatly, as do carbonate and pyritized silicate microfossils. The combined paleoenvironmental information from Site 959 and a close-by shelf site in Nigeria implies the general absence of eukaryotic surface-dwelling microplankton during peak PETM warmth in the eastern equatorial Atlantic, most likely caused by heat stress. We hypothesize, based on a literature survey, that heat stress might have reduced calcification in more tropical regions, potentially contributing to reduced deep sea carbonate accumulation rates, and, by buffering acidification, also to biological carbonate compensation of the injected carbon during the PETM. Crucially, abundant organic benthic foraminiferal linings imply sustained export production, likely driven by prokaryotes. In sharp contrast, the recovery of the CIE yields rapid (≪ 10 kyr) fluctuations in the abundance of several dinocyst groups, suggesting extreme ecosystem and environmental variability.

scholarly journals Tropical Atlantic Climate and Ecosystem Regime Shifts during the Paleocene-Eocene Thermal Maximum

2017 ◽  
Author(s):  
Joost Frieling ◽  
Gert-Jan Reichart ◽  
Jack J. Middelburg ◽  
Ursula Röhl ◽  
Thomas Westerhold ◽  
...  
Keyword(s):  
Environmental Variability ◽  
Equatorial Atlantic ◽  
Ocean Drilling Program ◽  
Tropical Regions ◽  
Surface Ocean ◽  
Ocean Drilling ◽  
Carbon Isotope Excursion ◽  
Thermal Maximum ◽  
Surface Dwelling ◽  
Upper Paleocene

Abstract. The Paleocene – Eocene Thermal Maximum (PETM; 56 Ma) was a phase of rapid global warming associated with massive carbon input into the ocean-atmosphere system from a 13C-depleted reservoir. Many mid- and high-latitude sections have been studied and document changes in salinity, hydrology and sedimentation, deoxygenation, biotic overturning and migrations, but detailed records from tropical regions are lacking. Here, we study the PETM at Ocean Drilling Program (ODP) Site 959 in the equatorial Atlantic using a range of organic and inorganic proxies and couple these with dinoflagellate cyst (dinocyst) assemblage analysis. The PETM at Site 959 was previously found to be marked by a ~3.8 ‰ negative carbon isotope excursion (CIE), and a ~4 ºC surface ocean warming from the uppermost Paleocene to peak PETM, of which ~1 ºC occurs before the onset of the CIE. We record upper Paleocene dinocyst assemblages that are similar to PETM assemblages as found in extra-tropical regions, confirming poleward migrations of ecosystems during the PETM. The early stages of the PETM are marked by a typical acme of the tropical genus Apectodinium, which reaches abundances of up to 95 %. Subsequently, dinocyst abundances diminish greatly, as do carbonate and pyritized silicate microfossils. The combined paleoenvironmental information from Site 959 and a close by shelf site in Nigeria implies the general absence of eukaryotic surface-dwelling microplankton during peak PETM warmth is most likely caused by heat stress. Crucially, abundant organic benthic foraminiferal linings imply sustained export production, likely driven by prokaryotes. In sharp contrast, the recovery of the CIE yields rapid (&amp;ll;10 kyr) fluctuations in the abundance of several dinocyst groups, suggesting extreme ecosystem and environmental variability.

scholarly journals Revisiting carbonate chemistry controls on planktic foraminifera Mg / Ca: implications for sea surface temperature and hydrology shifts over the Paleocene–Eocene Thermal Maximum and Eocene–Oligocene Transition

2015 ◽  
Vol 11 (4) ◽  
pp. 3143-3185 ◽  
Author(s):  
D. Evans ◽  
B. S. Wade ◽  
M. Henehan ◽  
J. Erez ◽  
W. Müller
Keyword(s):  
Laser Ablation ◽  
Carbonate Chemistry ◽  
Surface Hydrology ◽  
Planktic Foraminifera ◽  
Globigerinoides Ruber ◽  
Accurate Picture ◽  
Thermal Maximum ◽  
Vital Effects ◽  
Surface Dwelling ◽  
The Relationship

Abstract. Much of our knowledge of past ocean temperatures comes from the foraminifera Mg / Ca palaeothermometer. Several non-thermal controls on foraminifera Mg incorporation have been identified, of which vital-effects, salinity and secular variation in seawater Mg / Ca are the most commonly considered. Ocean carbonate chemistry is also known to influence Mg / Ca, yet this is rarely considered as a source of uncertainty either because (1) precise pH and [CO32−] reconstructions are sparse, or (2) it is not clear from existing culture studies how a correction should be applied. We present new culture data of the relationship between carbonate chemistry for the surface-dwelling planktic species Globigerinoides ruber, and compare our results to data compiled from existing studies. We find a coherent relationship between Mg / Ca and the carbonate system and argue that pH rather than [CO32−] is likely to be the dominant control. Applying these new calibrations to datasets for the Paleocene–Eocene Thermal Maximum (PETM) and Eocene–Oligocene Transition (EOT) enable us to produce a more accurate picture of surface hydrology change for the former, and a reassessment of the amount of subtropical precursor cooling for the latter. We show that properly corrected Mg / Ca and δ18O datasets for the PETM imply no salinity change, and that the amount of precursor cooling over the EOT has been previously underestimated by ∼ 2 °C based on Mg / Ca. Finally, we present new laser-ablation data of EOT-age Turborotalia ampliapertura from St Stephens Quarry (Alabama), for which a solution ICPMS Mg / Ca record is available (Wade et al., 2012). We show that the two datasets are in excellent agreement, demonstrating that fossil solution and laser-ablation data may be directly comparable. Together with an advancing understanding of the effect of Mg / Casw, the coherent picture of the relationship between Mg / Ca and pH that we outline here represents a step towards producing accurate and quantitative palaeotemperatures using this proxy.

Shelf and open-ocean calcareous phytoplankton assemblages across the Paleocene-Eocene Thermal Maximum: Implications for global productivity gradients

Geology ◽  
2006 ◽  
Vol 34 (4) ◽  
pp. 233 ◽  
Author(s):  
Samantha J. Gibbs ◽  
Timothy J. Bralower ◽  
Paul R. Bown ◽  
James C. Zachos ◽  
Laurel M. Bybell
Keyword(s):  
Open Ocean ◽  
Phytoplankton Assemblages ◽  
Thermal Maximum ◽  
Productivity Gradients

scholarly journals Comparison of outcome of total thyroidectomy with and without pre-operative calcium and vitamin D supplements in terms of post-operative hypocalcemia.

2021 ◽  
Vol 28 (08) ◽  
pp. 1200-1205
Author(s):  
Ahmed Siddique Ammar ◽  
◽  
Shehrbano Khattak ◽  
Ahmed Raza Noumani ◽  
Sahar Saeed ◽  
...  
Keyword(s):  
Vitamin D ◽  
Total Thyroidectomy ◽  
Early Discharge ◽  
Age Group ◽  
Common Occurrence ◽  
Surgical Ward ◽  
Group A ◽  
Vitamin D Supplements ◽  
Group B ◽  
Study Setting

Objective: The objective of this study is to compare the effect of pre-operative calcium and vitamin D supplements in terms of hypocalcemia in patients with total thyroidectomy. Study Design: Comparative study. Setting: EAST Surgical Ward, MAYO Hospital Lahore, Pakistan. Period: 1st July 2018 to 30th June 2020. Material & Methods: Sample size of 342 patients and duration of 2 years. 2 groups were created including 171 patients each. Group A patients received calcium and vitamin D supplements 1 week prior to total thyroidectomy while Group B patients didn’t receive any supplements. The results of both groups were compared. Data was collected by pre designed proforma and evaluated by SPSS 21. Results: 164 (47.9%) patients were male and 178 (52.0%) were females. Most common age group which undergone total thyroidectomy was between 31 years to 40 years. Total 140 patients (40.93%) experienced hypocalcemia. In group A, 32 (18.71%) experienced hypocalcemia while in group B 108 (63.1%) experienced hypocalcemia. The most common occurrence of hypocalcemia was noted on 1st post-operative day where 52 (37.14%) cases of hypocalcemia were reported. Conclusion: In a country with prevalent calcium and vitamin D deficiency the addition of these supplements one week prior to total thyroidectomy will lead to lesser incidence of hypocalcemia after total thyroidectomy and early discharge of the patient.

Electron microscopic radioautographic studies on the incorporation of 3H proline in the glomerular basement membrane (GBM) in antistreptococcal-cell-membrane (SCM) injected mice

1984 ◽  
Vol 42 ◽  
pp. 188-189
Author(s):  
R.P. Nayyar ◽  
C.F. Lange ◽  
J. L. Borke
Keyword(s):  
Body Weight ◽  
Cell Membrane ◽  
Basement Membrane ◽  
Glomerular Basement Membrane ◽  
Mesangial Matrix ◽  
Electron Microscopic ◽  
Group A ◽  
Injection Protocol

Streptococcal cell membrane (SCM) antiserum injected mice show a significant thickening of glomerular basement membrane (GBM) and an increase in mesangial matrix within 4 to 24 hours of antiserum administration (1,2,3). This study was undertaken to evaluate the incorporation of 3H proline into glomerular cells and GBM under normal and anti-SCM induced conditions. Mice were administered, intraperitoneally, 0.1 ml of normal or anti-SCM serum followed by a 10 µC/g body weight injection of 3H proline. Details of the preparation of anti-SCM (Group A type 12 streptococcal pyogenes) and other sera and injection protocol have been described elsewhere (2). After 15 minutes of isotope injection a chase of cold proline was given and animal sacrificed at 20 minutes, 1,2,4,8,24 and 48 hours. One of the removed kidneys was processed for immunofluorescence, light and electron microscopic radioautographic studies; second kidney was used for GBM isolation and aminoacid analysis.

Mitochondrial Changes in Cholestasis

1972 ◽  
Vol 30 ◽  
pp. 258-259
Author(s):  
F. G. Zaki
Keyword(s):  
Biliary Obstruction ◽  
Alcoholic Cirrhosis ◽  
Ultrastructural Changes ◽  
List Type ◽  
Common Occurrence ◽  
Extrahepatic Cholestasis ◽  
Mitochondrial Alteration ◽  
Extrahepatic Biliary Obstruction ◽  
Liver Biopsies ◽  
Mitochondrial Anomalies

Alterations of liver cell mitochondria represent pathologic phenomenon of a fundamental nature. Mitochondrial anomalies have been often described in association with cholestasis. In attempt to determine whether a given pattern of mitochondrial alteration has any correlation with the cause of cholestasis, liver biopsies were examined from 38 patients showing :a. extrahepatic cholestasis due to complete or partial extrahepatic biliary obstruction (8 cases proven at operation)b. intrahepatic cholestasis due to drugs (9 cases), viral hepatitis (6 cases) and alcoholic cirrhosis (15 cases).Mitochondria exhibiting ultrastructural changes due to aging or to the ‘wear and teart’ processes were not considered. In this study, the only profound and most prominent mitochondrial deformation was reported on basis of their common occurrence in randomly examined sections.

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