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Haynert, Kristin; Schönfeld, Joachim; Polovodova Asteman, Irina; Thomsen, Jörn (2012): The benthic foraminiferal community in a naturally CO2-rich coastal habitat of the southwestern Baltic Sea. PANGAEA,, Supplement to: Haynert, K et al. (2012): The benthic foraminiferal community in a naturally CO2-rich coastal habitat of the southwestern Baltic Sea. Biogeosciences, 9(11), 4421-4440,

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It is expected that the calcification of foraminifera will be negatively affected by the ongoing acidification of the oceans. Compared to the open oceans, these organisms are subjected to much more adverse carbonate system conditions in coastal and estuarine environments such as the southwestern Baltic Sea, where benthic foraminifera are abundant. This study documents the seasonal changes of carbonate chemistry and the ensuing response of the foraminiferal community with bi-monthly resolution in Flensburg Fjord. In comparison to the surface pCO2, which is close to equilibrium with the atmosphere, we observed large seasonal fluctuations of pCO2 in the bottom and sediment pore waters. The sediment pore water pCO2 was constantly high during the entire year ranging from 1244 to 3324 µatm. Nevertheless, in contrast to the bottom water, sediment pore water was slightly supersaturated with respect to calcite as a consequence of higher alkalinity (AT) for most of the year. Foraminiferal assemblages were dominated by two calcareous species, Ammonia aomoriensis and Elphidium incertum, and the agglutinated Ammotium cassis. The one-year cycle was characterised by seasonal community shifts. Our results revealed that there is no dynamic response of foraminiferal population density and diversity to elevated sediment pore water pCO2. Surprisingly, the fluctuations of sediment pore water undersaturation (Omega calc) co-vary with the population densities of living Ammonia aomoriensis. Further, we observed that most of the tests of living calcifying foraminifera were intact. Only Ammonia aomorienis showed dissolution and recalcification structures on the tests, especially at undersaturated conditions. Therefore, the benthic community is subjected to high pCO2 and tolerates elevated levels as long as sediment pore water remains supersaturated. Model calculations inferred that increasing atmospheric CO2 concentrations will finally lead to a perennial undersaturation in sediment pore waters. Whereas benthic foraminifera indeed may cope with a high sediment pore water pCO2, the steady undersaturation of sediment pore waters would likely cause a significant higher mortality of the dominating Ammonia aomoriensis. This shift may eventually lead to changes in the benthic foraminiferal communities in Flensburg Fjord, as well as in other regions experiencing naturally undersaturated Omega calc levels.
Ammonia aomoriensis; Ammotium cassis; Baltic Sea; Benthos; Calcification/Dissolution; Coast and continental shelf; Community composition and diversity; Elphidium albiumbilicatum; Elphidium excavatum clavatum; Elphidium excavatum excavatum; Elphidium gerthi; Elphidium incertum; Entire community; Field observation; Growth/Morphology; Reophax dentaliniformis; Soft-bottom community; Temperate
Further details:
Lavigne, Héloise; Gattuso, Jean-Pierre (2011): seacarb: seawater carbonate chemistry with R. R package version 2.4.
Median Latitude: 54.808425 * Median Longitude: 9.785696 * South-bound Latitude: 54.782000 * West-bound Longitude: 9.614000 * North-bound Latitude: 54.841670 * East-bound Longitude: 9.891500
Date/Time Start: 2009-06-01T00:00:00 * Date/Time End: 2009-06-30T00:00:00
Minimum DEPTH, water: m * Maximum DEPTH, water: 13 m
Flensburg_Fjord * Latitude: 54.801370 * Longitude: 9.884480 * Date/Time Start: 2009-06-01T00:00:00 * Date/Time End: 2009-06-30T00:00:00 * Elevation: -13.0 m * Method/Device: Experiment (EXP)
In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Lavigne and Gattuso, 2011) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2014-02-26.
#NameShort NameUnitPrincipal InvestigatorMethod/DeviceComment
1IdentificationIDHaynert, Kristin
2SpeciesSpeciesHaynert, Kristin
3Station labelStationHaynert, Kristin
6DEPTH, waterDepth watermGeocode
7DateDateHaynert, Kristin
8DescriptionDescriptionHaynert, Kristin
9Number of individualsInd No#Haynert, Kristin
10PercentagePerc%Haynert, Kristinindividual percentage
11Number of speciesSpec No#Haynert, Kristin
12Sample volumeSamp volcm3Haynert, Kristin
13SplitSplit#Haynert, Kristin
14Population densityDensity#/m3Haynert, Kristin
15Shannon Diversity IndexH'Haynert, Kristin
16Fishers alpha index of diversityFAIHaynert, Kristin
17PercentagePerc%Haynert, Kristinintact tests
18PercentagePerc%Haynert, Kristinlost of last chambers
19PercentagePerc%Haynert, Kristinlost of more than two chambers
20PercentagePerc%Haynert, Kristinliving benthic foraminifera %
21DiameterصmHaynert, Kristin
22SalinitySalHaynert, Kristin
23Temperature, waterTemp°CHaynert, Kristin
24Pressure, waterPressdbarHaynert, Kristin
25Alkalinity, totalATµmol/kgHaynert, Kristin
26Carbon, inorganic, dissolvedDICµmol/kgHaynert, Kristin
27Partial pressure of carbon dioxide (water) at sea surface temperature (wet air)pCO2water_SST_wetµatmHaynert, KristinCalculated using CO2SYS
28Calcite saturation stateOmega CalHaynert, KristinCalculated using CO2SYS
29Carbonate system computation flagCSC flagYang, YanCalculated using seacarb after Nisumaa et al. (2010)
30pHpHYang, YanCalculated using seacarb after Nisumaa et al. (2010)total scale
31Carbon dioxideCO2µmol/kgYang, YanCalculated using seacarb after Nisumaa et al. (2010)
32Partial pressure of carbon dioxide (water) at sea surface temperature (wet air)pCO2water_SST_wetµatmYang, YanCalculated using seacarb after Nisumaa et al. (2010)
33Fugacity of carbon dioxide (water) at sea surface temperature (wet air)fCO2water_SST_wetµatmYang, YanCalculated using seacarb after Nisumaa et al. (2010)
34Bicarbonate ion[HCO3]-µmol/kgYang, YanCalculated using seacarb after Nisumaa et al. (2010)
35Carbonate ion[CO3]2-µmol/kgYang, YanCalculated using seacarb after Nisumaa et al. (2010)
36Aragonite saturation stateOmega ArgYang, YanCalculated using seacarb after Nisumaa et al. (2010)
37Calcite saturation stateOmega CalYang, YanCalculated using seacarb after Nisumaa et al. (2010)
9266 data points

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