424 results on '"Spero, Howard J."'
Search Results
152. Marine Protozoa: Modern Planktonic Foraminifera . Ch. Hemleben, M. Spindler, and O. R. Anderson. Springer-Verlag, New York, 1989. xiv, 363 pp., illus. $98.
- Author
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Spero, Howard J., primary
- Published
- 1990
- Full Text
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153. The Cause of Carbon Isotope Minimum Events on Glacial Terminations.
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Spero, Howard J. and Lea, David W.
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ISOTOPES , *CARBON , *GLACIAL climates - Abstract
The occurrence of carbon isotope minima at the beginning of glacial terminations is a common feature of planktic foraminifera carbon isotopic records from the Indo-Pacific, sub-Antarctic, and South Atlantic. We use the δ[sup 13]C record of a thermocline-dwelling foraminifera, Neogloboquadrina dutertrei, and surface temperature estimates from the eastern equatorial Pacific to demonstrate that the onset of δ[sup 13]C minimum events and the initiation of Southern Ocean warming occurred simultaneously. Timing agreement between the marine record and the δ[sup 13]C minimum in an Antarctic atmospheric record suggests that the deglacial events were a response to the breakdown of surface water stratification, renewed Circumpolar Deep Water upwelling, and advection of low δ[sup 13]C waters to the convergence zone at the sub-Antarctic front. On the basis of age agreement between the absolute δ[sup 13]C minimum in surface records and the shift from low to high δ[sup 13]C in the deep South Atlantic, we suggest that the δ[sup 13]C rise that marks the end of the carbon isotope minima was due to the resumption of North Atlantic Deep Water influence in the Southern Ocean. [ABSTRACT FROM AUTHOR]
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- 2002
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154. The fate of nitrogen in the Orbulina universa foraminifera-symbiont system determined by nitrogen isotope analyses of shell-bound organic matter.
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Uhle, Maria E., Macko, Stephen A., Spero, Howard J., Lea, David W., Ruddiman, William F., and Engel, Michael H.
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- 1999
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155. Modern Foraminifera Barun K. Sen Gupta
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Spero, Howard J.
- Published
- 2000
156. SYMBIOSIS IN THE PLANKTONIC FORAMINIFER, ORBULINA UNIVERSA, AND THE ISOLATION OF ITS SYMBIOTIC DINOFLAGELLATE, GYMNODINIUM BÉII SP. NOV.
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Spero, Howard J.
- Subjects
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SYMBIOSIS , *PLANKTON , *FORAMINIFERA , *DINOFLAGELLATES , *GYMNODINIUM , *TEMPERATURE effect , *CELL division - Abstract
BSTRACT [ABSTRACT FROM AUTHOR]
- Published
- 1987
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- View/download PDF
157. CHEMOSENSORY CAPABILITIES IN THE PHAGOTROPHIC DINOFLAGELLATE <em>GYMNODINIUM FUNGIFORME</em>.
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Spero, Howard J.
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GYMNODINIUM , *AMINO acids , *ORGANIC compounds , *ALGAE - Abstract
Suggests that the non-photosynthetic, phagotrophic dinoflagellate, Gymnodinium fungiforme Anissimova is attracted to a variety of amino acids and other organic compounds. Most abundant free amino acids found in invertebrates and protozoa which are major food sources of denoflagellate; Exposure of species of cultured heterotrophic dinoflagellates to the water soluble fraction of a shrimp extract known to attract G. fungiforme.
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- 1985
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158. PHAGOTROPHY IN <em>GYMNODINIUM FINGIFORME</em> (PYRRHOPHYTA): THE PEDUNCLE AS AN ORGANELLE OF INGESTION.
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Spero, Howard J.
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GYMNODINIUM , *PLANT nutrition - Abstract
Examines the phagotrophic feeding behavior of Gymnodinium fungiforme. Life cycle; Mechanism for the functioning of the peduncle; Comparison with similar structures in other dinoflagellates.
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- 1982
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159. PHAGOTROPHIC FEEDING AND ITS IMPORTANCE TO THE LIFE CYCLE OF THE HOLOZOIC DINOFLAGELLATE, GYMNODINIUM FUNGIFORME.
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Spero, Howard J. and Morée, Montescue D.
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ANIMAL nutrition , *DINOFLAGELLATES , *GYMNODINIUM , *CYSTS (Pathology) - Abstract
The holozoic dinoflagellate, Gymnodinium fungiforme Anissimova, has been observed in both asexually and sexually reproducing culture. Asexual reproduction is characterized by zoosporangium formation and subsequent new cell release. Sexuality is gametic, and planozygoter and hypnozygotes are present. The life cycle is highly dependent on feeding and in food-depleted cultures the swimming cells rapidly disappear. These are replaced with resistant long-terms resting cysts. Despite its small size (8.5-19 μm), G. fungiforme can feed on prey as large as the (600-1000 μm in length), or small injured metozoans, and has been cultured phagotrophically with the chlorophyte, Dunaliella salina Teodoresco as a food source. Eleven additional species of algae including 1 chlorophyte, 7chrysophytes and 3rhodophytes however were not suitable as food sources feeding is characterized by the formation of dynamic aggregations' of hundreds of dinoflagellates that attach to the surface of a prey organism by a peduncle. G. fungiforme ingests the cytoplasm or body fluids of its prey and a feeding aggregation can ingest a C. magnum in 20-30 minutes. [ABSTRACT FROM AUTHOR]
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- 1981
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160. Sediment microhabitat effects on carbon stable isotopic signatures of microcosm-cultured benthic foraminifera.
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Chandler, G. Thomas, Williams, Douglas F., Spero, Howard J., and Xiaodong, Gao
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- 1996
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161. Oceanic pH control on the boron isotopic composition of foraminifera: Evidence from culture experiments.
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Sanyal, A., Hemming, N. G., Broecker, W. S., Lea, David W., Spero, Howard J., and Hanson, Gilbert N.
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- 1996
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162. SYMBIOSIS IN THE PLANKTONIC FORAMINIFER, <em>ORBULINA UNIVERSA</em>, AND THE ISOLATION OF ITS SYMBIOTIC DINOFLAGELLATE, <em>GYMNODINIUM BÉLL</em> SP. NOV.
- Author
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Spero, Howard J.
- Subjects
GYMNODINIUM ,DINOFLAGELLATES ,PLANKTON ,FORAMINIFERA - Abstract
The symbiotic association of the spinose planktonic foraminifer, Orbulina unviersa, with the dinoflagellate, Gymnodinium béii sp. Nov., was examined with light and electron microscopy, and the symbiont was isolated into unialgal culture. The intact asociation is characterized by a diurnal movement of the symbionts from the distal regions of the spines during the day, to perialgal vacuoles within the host cytoplasm at night. This diurnal migration involves a daily endo-exocytotic cycle. Gymnodinium béii is non-motile and spindle-shaped within the host, whereas it is motile and gymnodinoid in shape when in culture. Ultrastructural examination revealed two or more stalked pyrenoids penetrated by a lamellae, a typical dinokaryon nucleus and no trichocysts. A distinct 'flange' projects over the sulcus from the hypacone. The swimming behavior of this dinoflagellate was characterized by intermittent darting events. Swimming speeds during a dart reached veloctities of 770 μm·s[SUP-1] as compared to a mean, non-darting swimming velocity of 126 μm·s[SUP-1]. Gymnodinium béii is eurythermal and division rates ranged between 0.16 and 0.65 divisions day[SUP-1] for culture temperatures between 6.5 and 25°C respectively. [ABSTRACT FROM AUTHOR]
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- 1987
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163. Temperature influence on the carbon isotopic composition of Globigerina bulloidesand Orbulina universa(planktonic foraminifera)
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Bemis, Bryan E., Spero, Howard J., Lea, David W., and Bijma, Jelle
- Abstract
Laboratory experiments with the planktonic foraminifera Globigerina bulloides(nonsymbiotic) and Orbulina universa(symbiotic) were carried out to examine the effects of temperature, irradiance (symbiont photosynthesis), [CO32−], and ontogeny on shell δ13C values. In ambient seawater ([CO32−]= 171μmol kg–1), the δ13C of G. bulloidesshells decreases 0.11‰°C–1, a pattern that likely results from the incorporation of more respired CO2into shell carbon at higher metabolic rates. The δ13C of O. universashells grown under low light (LL) levels is insensitive to temperature and records the δ13C value of seawater ΣCO2, whereas the δ13C of high light (HL) shells increases slightly with temperature (0.05‰°C–1). HL O. universagrown in elevated [CO32−]seawater are isotopically depleted relative to those grown in ambient seawater, although it is uncertain from these experiments whether the [CO32−]influence on δ13C is affected by temperature. When applied to deep-sea core material, these results demonstrate that differences in sea surface temperature and [CO32−]can bias how we interpret downcore shifts in foraminiferal δ13C.
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- 2000
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164. Extracting environmental information from planktonic foraminiferal δ13C data.
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Spero, Howard J. and Williams, Douglas F.
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- 1988
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165. Marine Protozoa
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Spero, Howard J.
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- 1990
166. High‐Resolution Mg/Ca and δ18O Patterns in Modern Neogloboquadrina pachydermaFrom the Fram Strait and Irminger Sea
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Livsey, Caitlin M., Kozdon, Reinhard, Bauch, Dorothea, Brummer, Geert‐Jan A., Jonkers, Lukas, Orland, Ian, Hill, Tessa M., and Spero, Howard J.
- Abstract
Neogloboquadrina pachydermais the dominant species of planktonic foraminifera found in polar waters and is therefore invaluable for paleoceanographic studies of the high latitudes. However, the geochemistry of this species is complicated due to the development of a thick calcite crust in its final growth stage and at greater depths within the water column. We analyzed the in situ Mg/Ca and δ18O in discrete calcite zones using laser ablation‐inductively coupled plasma‐mass spectrometry, electron probe microanalysis, and secondary ion mass spectrometry within modern N. pachydermashells from the highly dynamic Fram Strait and the seasonally isothermal/isohaline Irminger Sea. Here we compare shell geochemistry to the measured temperature, salinity, and δ18Oswin which the shells calcified to better understand the controls on N. pachydermageochemical heterogeneity. We present a relationship between Mg/Ca and temperature in N. pachydermalamellar calcite that is significantly different than published equations for shells that contained both crust and lamellar calcite. We also document highly variable secondary ion mass spectrometry δ18O results (up to a 3.3‰ range in single shells) on plankton tow samples which we hypothesize is due to the granular texture of shell walls. Finally, we document that the δ18O of the crust and lamellar calcite of N. pachydermafrom an isothermal/isohaline environment are indistinguishable from each other, indicating that shifts in N. pachydermaδ18O are primarily controlled by changes in environmental temperature and/or salinity rather than differences in the sensitivities of the two calcite types to environmental conditions. Micron‐scale geochemical variability within modern N. pachydermashells is compared to the hydrographic conditionsWe propose a new Mg/Ca to temperature relationship for N. pachydermalamellar calciteThe sensitivity of N. pachydermaδ18O to temperature and salinity is the same in both lamellar and crust calcite
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- 2020
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167. 220 Year Diatom δ18O Reconstruction of the Guaymas Basin Thermocline Using Microfluorination
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Menicucci, Anthony J., Thunell, Robert C., and Spero, Howard J.
- Abstract
The removal of exchangeable oxygen from diatom opal prior to δ18Odiatomanalysis is a crucial first step before analyzing frustule oxygen isotopes for paleoceanographic applications. We present the results of experiments that quantify the temperature‐dependent reactivity of biogenic silica with water under laboratory conditions. We demonstrate that controlled exchange between rinse water and diatom opal at room temperature results in predictable alteration of δ18Odiatom, after vacuum dehydroxylation. Diatom samples equilibrated with an 18O‐enriched δ18Oequil. watersolution of +94.4‰ at ~21 °C for 70 hr prior to dehydroxylation yield δ18Odiatomdata that can be directly interpreted with existing empirical δ18Odiatomversus temperature relationships. We compare sediment trap‐based δ18Odiatomtemperature data with modern δ18Oforamtemperatures. Finally, we present an ~220 year record of δ18Odiatomdata from an eastern Pacific Guaymas Basin boxcore, analyzed using the microfluorination technique, that indicates diatom chlorophyll maximum (Chlmax) temperatures have shifted from a period during the late eighteenth and nineteenth centuries that was 8 °C cooler during the fall bloom relative to mean annual alkenone U37k′sea surface temperature, to the late twentieth century when we observe no difference between alkenone sea surface temperature and diatom Chlmax. These data suggest a twentieth century seasonal shift in the timing of fall upwelling and Guaymas Basin stratification breakdown that could be due to reduced upwelling efficiency and/or increased summer mixed layer thermal stratification. Diatom δ18O data show predictable alteration at ambient laboratory temperatures due to exchange with rinse water but is correctableGuaymas Basin diatom sediments biased toward the fall bloom and track well with existing foraminifera data setsDiatom δ18O temperatures record chlorophyll maximum temperatures warming by ~10°C over a 220 year time frame
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- 2020
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168. Figure S3 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
169. Timing and mechanism for intratest Mg/Ca variability in a living planktic foraminifer
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Spero, Howard J., Eggins, Stephen M., Russell, Ann D., Vetter, Lael, Kilburn, Matt R., and Hoenisch, Baerbel
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Paleoceanography ,Geochemistry ,13. Climate action ,Chemical oceanography ,14. Life underwater ,Chemical oceanography--Methodology ,Foraminifera, Fossil ,Microbiology - Abstract
Geochemical observations indicate that planktic foraminifer test Mg/Ca is heterogeneous in many species, thereby challenging its use as a paleotemperature proxy for paleoceanographic reconstructions. We present Mg/Ca and Ba/Ca data collected by laser ablation ICP-MS from the shells of Orbulina universa cultured in controlled laboratory experiments. Test calcite was labeled with Ba-spiked seawater for 12 h day or night calcification periods to quantify the timing of intratest Mg-banding across multiple diurnal cycles. Results demonstrate that high Mg bands are precipitated during the night whereas low Mg bands are precipitated during the day. Data obtained from specimens growing at 20 °C and 25 °C show that Mg/Ca ratios in both high and low Mg bands increase with temperature, and average test Mg/Ca ratios are in excellent agreement with previously published empirical calibrations based on bulk solution ICP-MS analyses. In general, Mg band concentrations decrease with increasing pH and/or [CO2−3] but this effect decreases as experimental temperatures increase from 20 °C to 25 °C. We suggest that mitochondrial uptake of Mg2+ from the thin calcifying fluid beneath streaming rhizopodial filaments may provide the primary locus for Mg2+ removal during test calcification, and that diurnal variations in either mitochondrial density or activity produce Mg banding. These results demonstrate that Mg banding is an inherent component of test biomineralization in O. universa and show that the Mg/Ca paleothermometer remains a fundamental tool for reconstructing past ocean temperatures from fossil foraminifers.
170. Text S4 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
- Author
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
- Subjects
TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
171. Planktic foraminifers as recorders of seawater Ba/Ca
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Hoenisch, Baerbel, Allen, Katherine Ann, Russell, Ann D., Eggins, Stephen M., Bijma, Jelle, Spero, Howard J., Lea, David W., and Yu, Jimin
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Marine biology ,Foraminifera--Ecology ,14. Life underwater ,Marine ecology - Abstract
Recent studies have used the Ba/Ca ratio of planktic foraminifer shells as a proxy for river run-off at oceanic sites near estuaries. Such studies assume that the Ba/Ca ratio in planktic foraminifer shells is primarily controlled by the Ba/Ca concentration of seawater and that other parameters such as salinity, temperature and pH do not compromise the primary Ba concentration relationship. Here we provide new insights from culture experiments and review published studies to confirm that environmental parameters including pH, temperature, salinity, and symbiont photosynthesis do not affect Ba substitution into planktic foraminiferal calcite. The partition coefficient for Ba in spinose planktic foraminifers is estimated as DBa = 0.15 ± 0.05 (95% confidence limits). The same factor also seems applicable to the non-spinose genus Neogloboquadrina but not to specimens of the non-spinose genus Globorotalia.
172. Text S2 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
- Author
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
- Subjects
TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
173. Controls on boron incorporation in cultured tests of the planktic foraminifer Orbulina universa
- Author
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Allen, Katherine Ann, Hoenisch, Baerbel, Eggins, Stephen M., Yu, Jimin, Spero, Howard J., and Elderfield, Henry
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Marine biology ,13. Climate action ,Marine ecology - Abstract
Culture experiments with living planktic foraminifers reveal that the ratio of boron to calcium (B/Ca) in Orbulina universa increases from 56 to 92 μmol mol−1 when pH is raised from 7.61+/–0.02 to 8.67+/–0.03 (total scale). Across this pH range, the abundances of carbonate, bicarbonate, and borate ions also change (+530, −500, and +170 μmol kg−1, respectively). Thus specific carbonate system control(s) on B/Ca remain unclear, complicating interpretation of paleorecords. B/Ca in cultured O. universa also increases with salinity (55–72 μmol mol−1 from 29.9–35.4‰) and seawater boron concentration (62–899 μmol mol−1 from 4–40 ppm B), suggesting that these parameters may need to be taken into account for paleorecords spanning large salinity changes (~ 2‰) and for samples grown in seawater whose boron concentration ([B]SW) differs from modern by more than 0.25 ppm. While our results are consistent with the predominant incorporation of the charged borate species B(OH)4−into foraminiferal calcite, the behavior of the partition coefficient KD (defined as [B/Ca]calcite/[B(OH)4−/HCO3−]seawater) cannot be explained by borate incorporation alone, and suggests the involvement of other pH-sensitive ions such as CO3 2− For a given increase in seawater B(OH)4−, the corresponding increase in B/Ca is stronger when B(OH)4− is raised by increasing [B]SW than when it is raised by increasing pH. These results suggest that B incorporation controls should be reconsidered. Additional insight is gained from laser-ablation ICP-MS profiles, which reveal variable B/Ca distributions within individual shells.
174. Figure S3 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
- Author
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
- Subjects
TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
175. Table S1 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
- Author
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
- Subjects
TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
176. Text S1 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
- Author
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
- Subjects
TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
177. Text S3 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
- Author
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
178. Figure S5 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
179. Figure S2 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
180. Figure S1 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
181. Text S4 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
182. Text S1 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
183. Text S3 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
184. Calibration of the carbon isotope composition (δ13C) of benthic foraminifera
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Filipsson, Helena L., Hoogakker, Babette, Herguera, Juan Carlos, Sikes, Elisabeth L., Cartapanis, Olivier, Curry, William B., Lynch-Stieglitz, Jean, Waelbroeck, Claire, Schmittner, Andreas, Oppo, Delia W., Mackensen, Andreas, Spero, Howard J., Lund, David C., Jaccard, Samuel, Gottschalk, Julia, Michel, Elisabeth, Galbraith, Eric D., Bostock, Helen C., Repschläger, Janne, Martinez-Mendez, Gema, Mix, Alan C., Lisiecki, Lorraine E., and Peterson, Carlye D.
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13. Climate action ,550 Earth sciences & geology ,14. Life underwater - Abstract
The carbon isotope composition (δ13C) of seawater provides valuable insight on ocean circulation, air-sea exchange, the biological pump, and the global carbon cycle and is reflected by the δ13C of foraminifera tests. Here more than 1700 δ13C observations of the benthic foraminifera genus Cibicides from late Holocene sediments (δ13CCibnat) are compiled and compared with newly updated estimates of the natural (preindustrial) water column δ13C of dissolved inorganic carbon (δ13CDICnat) as part of the international Ocean Circulation and Carbon Cycling (OC3) project. Using selection criteria based on the spatial distance between samples, we find high correlation between δ13CCibnat and δ13CDICnat, confirming earlier work. Regression analyses indicate significant carbonate ion (−2.6 ± 0.4) × 10−3‰/(μmol kg−1) [CO32−] and pressure (−4.9 ± 1.7) × 10−5‰ m−1 (depth) effects, which we use to propose a new global calibration for predicting δ13CDICnat from δ13CCibnat. This calibration is shown to remove some systematic regional biases and decrease errors compared with the one-to-one relationship (δ13CDICnat = δ13CCibnat). However, these effects and the error reductions are relatively small, which suggests that most conclusions from previous studies using a one-to-one relationship remain robust. The remaining standard error of the regression is generally σ ≅ 0.25‰, with larger values found in the southeast Atlantic and Antarctic (σ ≅ 0.4‰) and for species other than Cibicides wuellerstorfi. Discussion of species effects and possible sources of the remaining errors may aid future attempts to improve the use of the benthic δ13C record.
185. Table S2 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
186. Text S2 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
187. Figure S1 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
188. Figure S4 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
189. Table S1 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
190. Figure S2 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
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TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
191. The Influence of Salinity on Mg/Ca in Planktic Foraminifers – Evidence from Cultures, Core-top Sediments and Complementary δ18O
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Hoenisch, Baerbel, Allen, Katherine Ann, Lea, David W., Spero, Howard J., Eggins, Stephen M., Arbuszewski, Jennifer, DeMenocal, Peter B., Rosenthal, Yair, Russell, Ann D., and Elderfield, Henry
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13. Climate action ,Chemical oceanography ,14. Life underwater ,15. Life on land ,Biogeochemistry ,Paleoclimatology - Abstract
The Mg/Ca ratio in foraminiferal calcite is one of the principal proxies used for paleoceanographic temperature reconstructions, but recent core-top sediment observations suggest that salinity may exert a significant secondary control on planktic foraminifers. This study compiles new and published laboratory culture experiment data from the planktic foraminifers Orbulina universa, Globigerinoides sacculifer and Globigerinoides ruber, in which salinity was varied but temperature, pH and light were held constant. Combining new data with results from previous culture studies yields a Mg/Ca-sensitivity to salinity of 4.4 ± 2.3%, 4.7 ± 1.2%, and 3.3 ± 1.7% per salinity unit (95% confidence), respectively, for the three foraminifer species studied here. Comparison of these sensitivities with core-top data suggests that the much larger sensitivity (27 ± 4% per salinity unit) derived from Atlantic core-top sediments in previous studies is not a direct effect of salinity. Rather, we suggest that the dissolution correction often applied to Mg/Ca data can lead to significant overestimation of temperatures. We are able to reconcile culture calibrations with core-top observations by combining evidence for seasonal occurrence and latitude-specific habitat depth preferences with corresponding variations in physico-chemical environmental parameters. Although both Mg/Ca and δ18O yield temperature estimates that fall within the bounds of hydrographic observations, discrepancies between the two proxies highlight unresolved challenges with the use of paired Mg/Ca and δ18O analyses to reconstruct paleo-salinity patterns across ocean basins. The first step towards resolving these challenges requires a better spatially and seasonally resolved δ18Osw archive than is currently available. Nonetheless, site-specific reconstructions of salinity change through time may be valid.
192. Figure S5 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
- Subjects
TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
193. Table S2 from Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
- Author
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LeKieffre, Charlotte, Spero, Howard J., Fehrenbacher, Jennifer S., Russell, Ann D., Haojia Ren, Geslin, Emmanuelle, and Meibom, Anders
- Subjects
TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,14. Life underwater - Abstract
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13C-enriched inorganic carbon, 15N-nitrate and 15N-ammonium, as well as a 13C- and 15N- enriched heterotrophic food source, followed by TEM coupled to NanoSIMS isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15N-ammonium, indicating efficient ammonium assimilation. Only weak 15N-assimilation was observed after incubation with 15N-nitrate. Feeding foraminifers with 13C- and 15N-labelled food resulted in dinoflagellates that were labelled with 15N, thereby confirming the transfer of 15N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based paleoceanographic reconstructions, as they show that δ15N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
194. Extracting environmental information from planktonic foraminiferal δ13C data
- Author
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Spero, Howard J., primary and Williams, Douglas F., additional
- Published
- 1988
- Full Text
- View/download PDF
195. SYMBIOSIS IN THE PLANKTONIC FORAMINIFER,ORBULINA UNIVERSA, AND THE ISOLATION OF ITS SYMBIOTIC DINOFLAGELLATE,GYMNODINIUM BÉIISP. NOV.1
- Author
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Spero, Howard J., primary
- Published
- 1987
- Full Text
- View/download PDF
196. More light on photosymbiosis in fossil mollusks: The case of Mercenaria “tridacnoides”
- Author
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Jones, Douglas S., primary, Williams, Douglas F., additional, and Spero, Howard J., additional
- Published
- 1988
- Full Text
- View/download PDF
197. PHAGOTROPHIC FEEDING AND ITS IMPORTANCE TO THE LIFE CYCLE OF THE HOLOZOIC DINOFLAGELLATE,GYMNODINIUM FUNGIFORME1
- Author
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Spero, Howard J., primary and Morée, Montescue D., additional
- Published
- 1981
- Full Text
- View/download PDF
198. PHAGOTROPHY IN GYMNODINIUM FUNGIFORME (PYRRHOPHYTA): THE PEDUNCLE AS AN ORGANELLE OF INGESTION1
- Author
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Spero, Howard J., primary
- Published
- 1982
- Full Text
- View/download PDF
199. Shell Regeneration and Biological Recovery of Planktonic Foraminifera after Physical Injury Induced in Laboratory Culture
- Author
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Bé, Allan W. H., primary, Spero, Howard J., additional, and Be, Allan W. H., additional
- Published
- 1981
- Full Text
- View/download PDF
200. CHEMOSENSORY CAPABILITIES IN THE PHAGOTROPHIC DINOFLAGELLATE GYMNODINIUM FUNGIFORME11
- Author
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Spero, Howard J., primary
- Published
- 1985
- Full Text
- View/download PDF
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