نتایج جستجو برای: Foraminifera

تعداد نتایج: 4350  

2004
Jonathan B. Martin Shelley A. Day Anthony E. Rathburn Elena Perez Joris Gieskes

[1] Fossil foraminifera are critical to paleoceanographic reconstructions including estimates of past episodes of methane venting. These reconstructions rely on benthic foraminifera incorporating and retaining unaltered the ambient isotopic compositions of pore fluids and bottom waters. Comparisons are made here of isotopic compositions of abundant live and fossil foraminifera (Uvigerina peregr...

Journal: :Molecular biology and evolution 1994
J Pawlowski I Bolivar J Guiard-Maffia M Gouy

A 5'-terminal region of 1600-1800 base pairs was amplified, cloned, and sequenced in the large subunit rDNA (LSU rDNA) of four species of foraminifera. These sequences were compared with the homologous regions of 16 eukaryotic taxa in order to establish the phylogenetic position of foraminifera. Analysis of 610 unambiguously aligned bases shows that foraminifera branch closely to plasmodial and...

Journal: :Molecular biology and evolution 1997
J Pawlowski I Bolivar J F Fahrni C de Vargas M Gouy L Zaninetti

Foraminifera have one of the best known fossil records among the unicellular eukaryotes. However, the origin and phylogenetic relationships of the extant foraminiferal lineages are poorly understood. To test the current paleontological hypotheses on evolution of foraminifera, we sequenced about 1,000 base pairs from the 3' end of the small subunit rRNA gene (SSU rDNA) in 22 species representing...

Journal: :The Journal of eukaryotic microbiology 2008
Martin R Langer

Larger symbiont-bearing foraminifera are prominent and important producers of calcium carbonate in modern tropical environments. With an estimated production of at least 130 million tons of CaCO(3) per year, they contribute almost 5% of the annual present-day carbonate production in the world's reef and shelf areas (0-200 m) and approximately 2.5% of the CaCO(3) of all oceans. Together with non...

2006
Kunio Kaiho Kotaro Takeda Maria Rose Petrizzo James C. Zachos

Paleocene–Eocene warming and changes in oceanic hydrography should have significantly impacted the ecology of marine microorganisms, both at the surface and on the seafloor. We analyzed several key characteristics of foraminifera from two Shatsky Rise (ODP Leg 198) cores spanning the P/E boundary including the maximum test diameters of the largest calcareous trochospiral benthic foraminifera an...

Journal: :Science 1978
D F Williams R C Thunell J P Kennett

Major negative oxygen isotopic anomalies in planktonic foraminifera are associated with deep-sea anoxic mud layers (sapropels) deposited 9000 and 80,000 years ago in the eastern Mediterranean. The isotopic depletion in surface-dwelling foraminifera is significantly greater than in mesopelagic foraminifera. This difference in isotopic response suggests that surface-water salinities were drastica...

2003
Pawel Labaj Pawel Topa Jaroslaw Tyszka Witold Alda

This paper focuses on modelling and visualisation of mineral shells of foraminifera (unicellular aquatic, mainly marine, organisms). Our recent model follows the moving reference approach of theoretical modelling of foraminiferal shells. This model introduces three important aspects of simulations, i.e. non-circular chamber shapes (in 2D), allometry of chambers and three dimensional simulation ...

Journal: :Nature communications 2015
Erik van Sebille Paolo Scussolini Jonathan V Durgadoo Frank J C Peeters Arne Biastoch Wilbert Weijer Chris Turney Claire B Paris Rainer Zahn

Fossils of marine microorganisms such as planktic foraminifera are among the cornerstones of palaeoclimatological studies. It is often assumed that the proxies derived from their shells represent ocean conditions above the location where they were deposited. Planktic foraminifera, however, are carried by ocean currents and, depending on the life traits of the species, potentially incorporate di...

Journal: :Marine pollution bulletin 2013
L R Pettit M B Hart A N Medina-Sánchez C W Smart R Rodolfo-Metalpa J M Hall-Spencer R M Prol-Ledesma

Extensive CO2 vents have been discovered in the Wagner Basin, northern Gulf of California, where they create large areas with lowered seawater pH. Such areas are suitable for investigations of long-term biological effects of ocean acidification and effects of CO2 leakage from subsea carbon capture storage. Here, we show responses of benthic foraminifera to seawater pH gradients at 74-207m water...

Journal: :Philosophical transactions. Series A, Mathematical, physical, and engineering sciences 2002
Michal Kucera Kate F Darling

Shells of planktonic foraminifera recovered from marine sediments provide a multitude of important palaeoproxies. Most of these proxies are based on the assumption that each morphospecies of planktonic foraminifera represents a genetically continuous species with a unique habitat. Recent discovery of hitherto hidden genetic diversity among modern planktonic foraminifera has significant repercus...

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