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Langer, Gerald; Geisen, Markus; Baumann, Karl-Heinz; Kläs, Jessica; Riebesell, Ulf; Thoms, Silke; Young, Jeremy (2006): Seawater carbonate chemistry, growth rate and processes during experiments with Coccolithus pelagicus and Calcidiscus leptoporus, 2006. PANGAEA,, Supplement to: Langer, G et al. (2006): Species-specific responses of calcifying algae to changing seawater carbonate chemistry. Geochemistry, Geophysics, Geosystems, 7, Q09006,

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Uptake of half of the fossil fuel CO2 into the ocean causes gradual seawater acidification. This has been shown to slow down calcification of major calcifying groups, such as corals, foraminifera, and coccolithophores. Here we show that two of the most productive marine calcifying species, the coccolithophores Coccolithus pelagicus and Calcidiscus leptoporus, do not follow the CO2-related calcification response previously found. In batch culture experiments, particulate inorganic carbon (PIC) of C. leptoporus changes with increasing CO2 concentration in a nonlinear relationship. A PIC optimum curve is obtained, with a maximum value at present-day surface ocean pCO2 levels (?360 ppm CO2). With particulate organic carbon (POC) remaining constant over the range of CO2 concentrations, the PIC/POC ratio also shows an optimum curve. In the C. pelagicus cultures, neither PIC nor POC changes significantly over the CO2 range tested, yielding a stable PIC/POC ratio. Since growth rate in both species did not change with pCO2, POC and PIC production show the same pattern as POC and PIC. The two investigated species respond differently to changes in the seawater carbonate chemistry, highlighting the need to consider species-specific effects when evaluating whole ecosystem responses. Changes of calcification rate (PIC production) were highly correlated to changes in coccolith morphology. Since our experimental results suggest altered coccolith morphology (at least in the case of C. leptoporus) in the geological past, coccoliths originating from sedimentary records of periods with different CO2 levels were analyzed. Analysis of sediment samples was performed on six cores obtained from locations well above the lysocline and covering a range of latitudes throughout the Atlantic Ocean. Scanning electron micrograph analysis of coccolith morphologies did not reveal any evidence for significant numbers of incomplete or malformed coccoliths of C. pelagicus and C. leptoporus in last glacial maximum and Holocene sediments. The discrepancy between experimental and geological results might be explained by adaptation to changing carbonate chemistry.
Langer_etal_06 * Device: Experiment (EXP)
#NameShort NameUnitPrincipal InvestigatorMethodComment
1SpeciesSpeciesLanger, Gerald
2Experimental treatmentExp treatLanger, Gerald
3Temperature, waterTemp°CLanger, Gerald
4Radiation, photosynthetically activePARµmol/m2/sLanger, Gerald
5Light:Dark cycleL:Dhh:hhLanger, Gerald
6pHpHLanger, GeraldCalculated using CO2SYS
7Alkalinity, totalATµmol/kgLanger, GeraldTitration potentiometric
8Carbon, inorganic, dissolvedDICµmol/kgLanger, GeraldTitration potentiometric
9Carbon dioxideCO2µmol/kgLanger, GeraldCalculated using CO2SYS
10Bicarbonate ion[HCO3]-µmol/kgLanger, GeraldCalculated using CO2SYS
11Carbonate ion[CO3]2-µmol/kgLanger, GeraldCalculated using CO2SYS
12Partial pressure of carbon dioxide (water) at sea surface temperature (wet air)pCO2water_SST_wetµatmLanger, GeraldCalculated using CO2SYS
13Aragonite saturation stateOmega ArgLanger, GeraldCalculated using CO2SYS
14Carbon, organic, particulate, per cellPOCpg/#Langer, GeraldElement analyser CNS, Carlo Erba NA1500
15Carbon, inorganic, particulate, per cellPIC/cellpg/#Langer, Gerald
16Carbon organic/inorganic ratioCO/CILanger, Geraldof particulate fraction
17Growth rateµ#/dayLanger, Gerald
18Coccoliths, sphere sizeCocco sphere sizeµmLanger, Gerald
19CoccolithsCoccoLanger, Geraldper cell
20CoccolithsCocco%Langer, Geraldnormal per cell
21CoccolithsCocco%Langer, Geraldmalformed per cell
22CoccolithsCocco%Langer, Geraldincompletely grown
189 data points

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