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  • 1
    Language: English
    In: Science (New York, N.Y.), 09 January 2004, Vol.303(5655), pp.207-10
    Description: We characterize the evolutionary radiation of planktic foraminifera by the test size distributions of entire assemblages in more than 500 Cenozoic marine sediment samples, including more than 1 million tests. Calibration of Holocene size patterns with environmental parameters and comparisons with Cenozoic paleoproxy data show a consistently positive correlation between test size and surface-water stratification intensity. We infer that the observed macroevolutionary increase in test size of planktic foraminifera through the Cenozoic was an adaptive response to intensifying surface-water stratification in low latitudes, which was driven by polar cooling.
    Keywords: Biological Evolution ; Plankton
    ISSN: 00368075
    E-ISSN: 1095-9203
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  • 2
    Language: English
    In: Geology, Feb, 2010, Vol.38(1), p.103(4)
    Description: Planktic foraminiferal size-normalized weight (SNW) has been used as a proxy for both past changes in deepwater dissolution and surface ocean [C[O.sup.2-.sub.3], the latter potentially providing a way to evaluate paleoatmospheric pC[O.sub.2] variations beyond the ice core records. Here we examine the relationship between SNW in modern planktic foraminifera and surface water [C[O.sup.2-.sub.3] in the Arabian Sea using a suite of samples obtained from plankton net casts in surface waters having a large range in their carbon chemistry. Our results reveal substantial interspecies- and intraspecies-specific variations in the strength, gradient, and even sign of this relationship, indicating that [C[O.sup.2-.sub.3] does not exert a dominant control on foraminiferal test weight. Similarly, foraminiferal abundance data do not lend support to the hypothesis that SNW responds to optimal growth conditions. Further work is needed, perhaps in laboratory cultures, to determine those environmental factors that are simply correlated with SNW and those that exert control. doi: 10.1130/G30150.1
    Keywords: Foraminifera -- Research ; Oceans -- Environmental Aspects ; Plankton -- Chemical Properties
    ISSN: 0091-7613
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Earth and Planetary Science Letters, Feb 15, 2012, Vol.319-320, p.133(13)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.epsl.2011.12.002 Byline: Oliver Friedrich, Ralf Schiebel, Paul A. Wilson, Syee Weldeab, Christopher J. Beer, Matthew J. Cooper, Jens Fiebig Keywords: Mg/Ca; planktic foraminifera; ecology; dissolution; core-top; plankton tow Abstract: Mg/Ca palaeothermometry in foraminiferal calcite is a widely applied tool in palaeoceanography. However, our understanding of the effects of planktic foraminiferal ecology and early diagenesis on test calcite Mg/Ca is limited. Here we report results of a study designed to shed new light on ecological, size-related and very early (water column) diagenetic controls on Mg/Ca in planktic foraminiferal calcite. We analysed Mg/Ca and stable isotopes of nine modern planktic foraminiferal species across fourteen mostly 50[mu]m-window sieve fractions in a core-top sample from the North Atlantic Ocean. We also analysed Mg/Ca in four of these nine species from plankton-tow samples collected from 0 to 2500m water depth in the North Atlantic Ocean and Arabian Sea. Our core-top study confirms that sensitivity of Mg/Ca to change in test size is species-specific but reveals an overall decrease in Mg/Ca with increasing test size in all but one species, Orbulina universa, for which Mg/Ca increases with size. These findings are broadly consistent with known ecological behaviour suggesting that the size-related signal is largely environmentally rather than calcification-rate controlled. Our results underscore the need to undertake Mg/Ca palaeothermometry on narrow size fractions of planktic foraminifers, particularly for shallow-dwelling species such as G. bulloides and G. ruber where Mg/Ca is most sensitive to test size across the size range of 200-350[mu]m. Our plankton-tow data from the Arabian Sea are in agreement with in-situ temperatures. In contrast, our data from the North Atlantic Ocean reveal large variability and marked offsets (to warmer values) from in-situ temperatures that are interpreted to reflect lateral advection from the south, storm-induced vertical mixing of the water column and/or the influence of surface-water salinity on the Mg/Ca signal. None of our plankton-tow Mg/Ca data shows any evidence of test dissolution in the water column. Our study provides important verification that the Mg/Ca signal recorded during calcification does not undergo diagenetic degradation during test transport to the sea floor, thereby satisfying an important precondition of its palaeo-proxy utility. Article History: Received 8 April 2011; Revised 30 November 2011; Accepted 1 December 2011 Article Note: (miscellaneous) Editor G. Henderson
    Keywords: Diagenesis (Geology) ; Advection (Earth sciences) ; Human-environment Interactions ; Ocean Bottom ; Salinity ; Cancer Research ; Calcite Crystals ; Carbonates
    ISSN: 0012-821X
    Source: Cengage Learning, Inc.
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  • 4
    Language: English
    In: Earth and Planetary Science Letters, Feb 15, 2012, Vol.319-320, p.133(13)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.epsl.2011.12.002 Byline: Oliver Friedrich, Ralf Schiebel, Paul A. Wilson, Syee Weldeab, Christopher J. Beer, Matthew J. Cooper, Jens Fiebig Keywords: Mg/Ca; planktic foraminifera; ecology; dissolution; core-top; plankton tow Abstract: Mg/Ca palaeothermometry in foraminiferal calcite is a widely applied tool in palaeoceanography. However, our understanding of the effects of planktic foraminiferal ecology and early diagenesis on test calcite Mg/Ca is limited. Here we report results of a study designed to shed new light on ecological, size-related and very early (water column) diagenetic controls on Mg/Ca in planktic foraminiferal calcite. We analysed Mg/Ca and stable isotopes of nine modern planktic foraminiferal species across fourteen mostly 50[mu]m-window sieve fractions in a core-top sample from the North Atlantic Ocean. We also analysed Mg/Ca in four of these nine species from plankton-tow samples collected from 0 to 2500m water depth in the North Atlantic Ocean and Arabian Sea. Our core-top study confirms that sensitivity of Mg/Ca to change in test size is species-specific but reveals an overall decrease in Mg/Ca with increasing test size in all but one species, Orbulina universa, for which Mg/Ca increases with size. These findings are broadly consistent with known ecological behaviour suggesting that the size-related signal is largely environmentally rather than calcification-rate controlled. Our results underscore the need to undertake Mg/Ca palaeothermometry on narrow size fractions of planktic foraminifers, particularly for shallow-dwelling species such as G. bulloides and G. ruber where Mg/Ca is most sensitive to test size across the size range of 200-350[mu]m. Our plankton-tow data from the Arabian Sea are in agreement with in-situ temperatures. In contrast, our data from the North Atlantic Ocean reveal large variability and marked offsets (to warmer values) from in-situ temperatures that are interpreted to reflect lateral advection from the south, storm-induced vertical mixing of the water column and/or the influence of surface-water salinity on the Mg/Ca signal. None of our plankton-tow Mg/Ca data shows any evidence of test dissolution in the water column. Our study provides important verification that the Mg/Ca signal recorded during calcification does not undergo diagenetic degradation during test transport to the sea floor, thereby satisfying an important precondition of its palaeo-proxy utility. Article History: Received 8 April 2011; Revised 30 November 2011; Accepted 1 December 2011 Article Note: (miscellaneous) Editor G. Henderson
    Keywords: Calcite Crystals ; Diagenesis (Geology) ; Advection (Earth sciences) ; Carbonates ; Ocean Bottom ; Human-environment Interactions
    ISSN: 0012-821X
    Source: Cengage Learning, Inc.
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  • 5
    In: Journal of Geophysical Research: Oceans, August 2011, Vol.116(C8), pp.n/a-n/a
    Description: Production and dispersion of coccolithophores are assessed within their ecologic and hydrographic context across enhanced spring chlorophyll production in the surface eastern North Atlantic. Within a 4 day period from 12 to 16 March 2004, a N–S transect from 47°N to 33°N was sampled along 20°W. Water samples from defined depths down to 200 m were analyzed for coccolithophores from 0.45 m polycarbonate filters by scanning electron microscopy. At 47°N coccolithophores flourished when euphotic conditions allowed new production at deep mixing, low temperatures, and high nutrient concentrations. flourished at high turbulence during an early stage of the phytoplankton succession and contributed half of the total coccolithophore assemblage, with up to 150 × 10 cells L and up to 12 × 10 cells m when integrated over the upper 200 m of the water column. Maximum chlorophyll concentrations occurred just north of the Azores Front, at 37°N–39°N, at comparatively low numbers of coccolithophores. To the south, at 35°N–33°N, coccolithophores were abundant within calm and stratified Subtropical Mode Waters, and was the dominant species again. Although the cell densities of coccolithophores observed here remained below those typical of plankton blooms visible from satellite images, the depth‐integrated total mass makes them significant producers of calcite and contributors to the total carbon sedimentation at a much wider range of ecological conditions during late winter and early spring than hitherto assumed. Coccolithophore production and dispersion Coccolithophores and the open marine calcite budget Coccolithophore ecology
    Keywords: Emiliania Huxleyi ; Biogeochemistry ; Carbonate Production ; Coccolithophores ; Micropaleontology ; Paleoceanography
    ISSN: 0148-0227
    ISSN: 21699275
    E-ISSN: 2156-2202
    E-ISSN: 21699291
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  • 6
    Language: English
    In: Marine Micropaleontology, 2011, Vol.80(3), pp.89-100
    Description: Population dynamics of planktic foraminifer species are discussed in relation to environmental factors across the continental slope onto the shelf of the southeastern Bay of Biscay. Along a bathymetric transect from 2000 m to 145 m water depth, 154 vertical plankton tows were obtained during different seasons on five cruises between June 2006 and July 2008. The distribution of live specimens (〉 100 μm) sampled at distinct intervals down to 700 m water depth is compared to changes in temperature, salinity, and chlorophyll- concentration. The overall seasonal variability and depth distribution of species in the hemipelagic southeastern Bay of Biscay has been similar to open ocean faunas in the pelagic North Atlantic. Each species examined occurred at considerable variability in habitat depth and seasonal distribution. The vertical distribution of planktic foraminifer species was mainly driven by the depth of the Deep Chlorophyll Maximum (DCM) and hence linked to the development of the thermocline. The seasonal variation of river discharge could have had differential effects on the distribution of planktic foraminifers, and may have inhibited or triggered the production of species. Low standing stocks at onshore stations in spring, and high standing stocks in July both in low saline waters indicate that salinity in itself did not control the distribution of planktic foraminifers. Instead, factors which co-vary with salinity, such as turbidity and organic matter possibly affected the distribution of planktic foraminifers on a species-specific scale. In general, the distribution of planktic foraminifer species on a seasonal, vertical, and regional scale along the offshore–onshore transect was related to surface water salinity and turbidity, and to the availability of food. ► Succession of planktic foraminifers in the SE Bay of Biscay is similar to the pelagic North Atlantic. ► Vertical distribution of planktic foraminifers is driven by the development of the thermocline. ► Seasonal variation of river discharge inhibits or triggers production of species. ► Turbidity and organic matter derived from the continent affected the species distribution. ► In general, the distribution of pl. foraminifer species was related to food, salinity and turbidity.
    Keywords: Planktic Foraminifera ; Ecology ; Population Dynamic ; Seasonality ; Bay of Biscay ; Geology ; Ecology
    ISSN: 0377-8398
    E-ISSN: 1872-6186
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  • 7
    Language: English
    In: Journal of Marine Systems, Jan, 2013, Vol.109-110, p.S169-S181
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jmarsys.2011.11.026 Byline: Tanja Kuhnt, Helene Howa, Sabine Schmidt, Louis Marie, Ralf Schiebel Keywords: Planktic foraminifera; Bay of Biscay; Sediment traps; Particulate mass flux;.sup.210Pb; Seasonality; Lateral advection Abstract: The temporal and water depth related dynamics of planktic foraminiferal fluxes in the south-eastern Bay of Biscay are discussed for a two year sampling period (June 2006-June 2008). Two sediment traps deployed at 800m and 1700m water depth at a mooring in 2000m of water depth, were analyzed for the flux of planktic foraminiferal species 〉150[mu]m, in comparison with the total mass flux. Total flux of planktic foraminifera shows seasonal maxima in spring/early summer (〉2000Ind.m.sup.-2 d.sup.-1) and minima from late summer through winter (〈10 Ind.m.sup.-2 d.sup.-1). The flux of planktic foraminiferal tests in the intermediate to deep water column at the inner Bay of Biscay comprises an intermittent and regionally variable signal of seasonal surface water primary productivity. Significant lateral transport and flux of particles superimposed on the downward mass flux indicate a decoupling of fluxes between the 800-m and 1700-m traps. The.sup.210Pb budget and the presence of certain benthic foraminiferal species in the midwater column prove that the lateral flux originated from the upper continental slope. Despite the temporal and vertical variations of the particulate flux, a well-defined seasonal flux signal can be deduced from the frequency of planktic foraminiferal species. Article History: Received 14 September 2010; Revised 7 November 2011; Accepted 30 November 2011
    Keywords: Sediments (Geology) -- Analysis
    ISSN: 0924-7963
    Source: Cengage Learning, Inc.
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  • 8
    Language: English
    In: Deep-Sea Research. Part I, Oceanographic Research Papers, June, 2012, Vol.64, p.146(11)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2012.02.004 Byline: Michael Siccha (a)(c), Ralf Schiebel (a), Sabine Schmidt (b), Helene Howa (a) Keywords: Drifting sediment traps; Planktic foraminifera; Test flux; Patchiness; Autocorrelation Abstract: Test fluxes of planktic foraminifera in the Bay of Biscay were sampled in spring using drifting sediment traps deployed at 200m depth. At a temporal and spatial resolution of 3h and approximately 1km the foraminifer flux varied with a factor of 5. The consecutive deployments within the same area, at distances of [approximately equal to]50km differed significantly in flux and relative species abundances. Flux sequences of the total foraminifer assemblage and individual species were significantly autocorrelated. The significance of autocorrelation analyses was affected by sample size of the flux sequences and limited to flux sequences with large fluxes. Autocorrelation in planktic foraminifer fluxes and standing stocks was restricted to distances 〈2km, and were not attributed to the temporal domain. Author Affiliation: (a) Laboratory of Recent and Fossil Bio-indicators (BIAF), Angers University, UPRES EA 2644, 2 Boulevard Lavoisier, 49045 Angers Cedex, France (b) UMR-CNRS 5805 EPOC, Universite de Bordeaux, Avenue de Facultes, 33405 Talence Cedex, France (c) The Hebrew University of Jerusalem, Fredy & Nadine Herrmann Institute of Earth Sciences, Edmond J. Safra Campus, Givat Ram, Jerusalem 91904, Israel Article History: Received 15 August 2011; Revised 13 February 2012; Accepted 15 February 2012
    Keywords: Sediments (Geology)
    ISSN: 0967-0637
    Source: Cengage Learning, Inc.
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  • 9
    Language: English
    In: Science, 09 January 2004, Vol.303(5655), pp.207-210
    Description: We characterize the evolutionary radiation of planktic foraminifera by the test size distributions of entire assemblages in more than 500 Cenozoic marine sediment samples, including more than 1 million tests. Calibration of Holocene size patterns with environmental parameters and comparisons with Cenozoic paleoproxy data show a consistently positive correlation between test size and surface-water stratification intensity. We infer that the observed macroevolutionary increase in test size of planktic foraminifera through the Cenozoic was an adaptive response to intensifying surface-water stratification in low latitudes, which was driven by polar cooling.
    Keywords: Abiogenesis ; Plankton ; Biological Evolution ; Cenozoic Era ; Marine Environments ; Adaptation ; Sediments ; Oceanography ; Cooling ; Life Sciences (General) (Ah) ; Article;
    ISSN: 00368075
    E-ISSN: 10959203
    Source: Archival Journals (JSTOR)
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  • 10
    Language: English
    In: Geochimica et Cosmochimica Acta, 15 November 2017, Vol.217, pp.365-383
    Description: An important tool for deep-sea temperature reconstruction is Mg/Ca paleothermometry applied to benthic foraminifera. Foraminifera of the genus appear to be promising candidates for temperature reconstructions due to their wide geographical and bathymetric distribution, and their infaunal habitat, which was suggested to reduce secondary effects from carbonate ion saturation (Δ[CO ]). Here, we make substantial advances to previous calibration efforts and present new multi-lab Mg/Ca data for and from more than one hundred core top samples spanning bottom temperatures from −1 to 16 °C, coupled with morphometric analyses of the foraminifer tests. Both species and their morphotypes seem to have a similar response of Mg/Ca to growth temperature. Compilation of new and previously published data reveals a linear dependence of temperature on Mg/Ca, with a best fit of Mg/Ca (mmol/mol) = 0.113 ± 0.005 ∗ (°C) + 0.792 ± 0.036 (r = 0.81; n = 120; 1σ SD). Salinity, bottom water Δ[CO ], and varying morphotypes have no apparent effect on the Mg/Ca-temperature relationship, but pore water Δ[CO ] might have had an influence on some of the samples from the tropical Atlantic.
    Keywords: Paleoceanography ; Mg/Ca Paleothermometry ; Temperature Calibration ; Deep-Sea Temperature Reconstruction ; Benthic Foraminifera ; Melonis Barleeanum ; Melonis Pompilioides ; Geology
    ISSN: 0016-7037
    E-ISSN: 1872-9533
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