The chemical microenvironment of the symbiotic planktonic foraminifer<i>Orbulina universa</i>

Köhler-Rink, Stephanie; Kühl, Michael

doi:10.1080/17451000510019015

Cited by 63 publications

(47 citation statements)

References 65 publications

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“…2) is in accordance with previous microsensor measurements, showing high spatial variability of Ca 2+ microgradients in Amphistegina lobifera and Marginopora vertebralis (Koehler- Rink and Kuehl, 2000) and among specimens in Orbulina universa (Koehler- Rink and Kuehl, 2005). This indicates that Ca 2+ uptake varies temporally and spatially over the shell surface of Ammonia sp.…”

Section: Calcium Dynamicssupporting

confidence: 78%

Calcification acidifies the microenvironment of a benthic foraminifer (Ammonia sp.)

Glas

Langer

Keul

2012

Journal of Experimental Marine Biology and Ecology

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Calcareous foraminifera are well known for their CaCO 3 shells. Yet, CaCO 3 precipitation acidifies the calcifying fluid. Calcification without pH regulation would therefore rapidly create a negative feedback for CaCO 3 precipitation. In unicellular organisms, like foraminifera, an effective mechanism to counteract this acidification could be the externalization of H + from the site of calcification. In this study we show that a benthic symbiont-free foraminifer Ammonia sp. actively decreases pH within its extracellular microenvironment only while precipitating calcite. During chamber formation events the strongest pH decreases occurred in the vicinity of a newly forming chamber (range of gradient~100 μm) with a recorded minimum of 6.31 (b 10 μm from the shell) and a maximum duration of 7 h. The acidification was actively regulated by the foraminifera and correlated with shell diameters, indicating that the amount of protons removed during calcification is directly related to the volume of calcite precipitated. The here presented findings imply that H + expulsion as a result of calcification may be a wider strategy for maintaining pH homeostasis in unicellular calcifying organisms.

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Section: Calcium Dynamicssupporting

confidence: 78%

Calcification acidifies the microenvironment of a benthic foraminifer (Ammonia sp.)

Glas

Langer

Keul

2012

Journal of Experimental Marine Biology and Ecology

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“…Thus photosynthesis is calculated on a per symbiont basis multiplied by the symbiont number of a 250 µm sized foraminifer (s nb ). Photosynthesis also depends on light availability (L, µmole photon m −2 s −1 ) and reaches saturation for high light intensities (Jørgensen et al, 1985;Köhler-Rink and Kühl 2005;Spero and Parker, 1985). The model reproduces this process by using a Michaelis-Menten relationship as a function of the light availability.…”

Section: Photosynthesis and Respirationmentioning

confidence: 92%

Modelling planktic foraminifer growth and distribution using an ecophysiological multi-species approach

et al. 2011

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Abstract. We present an eco-physiological model reproducing the growth of eight foraminifer species (Neogloboquadrina pachyderma, Neogloboquadrina incompta, Neogloboquadrina dutertrei, Globigerina bulloides, Globigerinoides ruber, Globigerinoides sacculifer, Globigerinella siphonifera and Orbulina universa). By using the main physiological rates of foraminifers (nutrition, respiration, symbiotic photosynthesis), this model estimates their growth as a function of temperature, light availability, and food concentration. Model parameters are directly derived or calibrated from experimental observations and only the influence of food concentration (estimated via Chlorophyll-a concentration) was calibrated against field observations. Growth rates estimated from the model show positive correlation with observed abundance from plankton net data suggesting close coupling between individual growth and population abundance. This observation was used to directly estimate potential abundance from the model-derived growth. Using satellite data, the model simulate the dominant foraminifer species with a 70.5% efficiency when compared to a data set of 576 field observations worldwide. Using outputs of a biogeochemical model of the global ocean (PISCES) instead of satellite images as forcing variables gives also good results, but with lower efficiency (58.9%). Compared to core tops observations, the model also correctly reproduces the relative worldwide abundance and the diversity of the eight species when using either satellite data either PISCES Correspondence to: F. Lombard (lombardfa@gmail.com) results. This model allows prediction of the season and water depth at which each species has its maximum abundance potential. This offers promising perspectives for both an improved quantification of paleoceanographic reconstructions and for a better understanding of the foraminiferal role in the marine carbon cycle.

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“…The pH increase leads locally to a carbonate increase, which results in higher Ω. It is well documented that upon illumination calcification increases in foraminifera (Erez 1983;Köhler-Rink and Kühl 2005;Lea et al 1995). Due to calcification, the calcium concentration at the shell surface decreased more strongly in the light.…”

Section: +mentioning

confidence: 99%

A microsensor for carbonate ions suitable for microprofiling in freshwater and saline environments

Beer

Bissett

Wit

et al. 2008

Limnology & Ocean Methods

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A novel carbonate microsensor, based on the ion-selective ionophore N,N,-dioctyl-3α,12 α-bis(4-trifluoroacetylbenzoxy)-5β-cholan-24-amide, is presented. The sensor chemistry and filling electrolyte, used previously for macrosensors, was improved for use in microsensors, and a simple calibration procedure was designed. The sensor is highly selective for carbonate, having a similar selectivity as the macrosensor, and is so insensitive to Cl -interference that it can be used in seawater. The ability to measure accurate profiles with the carbonate sensor was verified in agar gels with artificial carbonate gradients. Several environmental applications are presented, including photosynthesis and calcification measurements in freshwater stromatolites (tufas) and foraminifera. Carbonate profiles in illuminated and darkened hypersaline microbial mats were qualitatively as expected and aligned with the oxygen and pH profiles. The dissolved inorganic carbon profiles calculated from local pH and carbonate values, however, did not follow the expected trends, both in the foraminifera and the hypersaline mat. Temporal and spatial heterogeneities make perfect alignment of pH and carbonate profiles, needed for DIC calculations, unrealistic. The calculation of dissolved inorganic carbon microprofiles from pH and carbonate microprofiles is not recommended. The microsensor is highly useful in studies on calcification and decalcification, where direct concentrations of carbonate and calcium ions are needed.

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The chemical microenvironment of the symbiotic planktonic foraminiferOrbulina universa

Cited by 63 publications

References 65 publications

Calcification acidifies the microenvironment of a benthic foraminifer (Ammonia sp.)

Calcification acidifies the microenvironment of a benthic foraminifer (Ammonia sp.)

Modelling planktic foraminifer growth and distribution using an ecophysiological multi-species approach

A microsensor for carbonate ions suitable for microprofiling in freshwater and saline environments

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