Dissolution of coccolithophorid calcite by microzooplankton and copepod grazing
Independent of the ongoing acidification of surface seawater, the majority of the calciumcarbonate produced in the pelagial is dissolved by natural processes above thelysocline. We investigate to what extent grazing and passage of coccolithophorids5 through the guts of copepods and the food vacuoles...
| Main Authors: | , , , , , , , |
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| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Copernicus GmbH
2008
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/bgd-5-1-2008 http://ecite.utas.edu.au/72203 |
| Summary: | Independent of the ongoing acidification of surface seawater, the majority of the calciumcarbonate produced in the pelagial is dissolved by natural processes above thelysocline. We investigate to what extent grazing and passage of coccolithophorids5 through the guts of copepods and the food vacuoles of microzooplankton contributeto calcite dissolution. In laboratory experiments where the coccolithophorid Emilianiahuxleyi was fed to the rotifer Brachionus plicatilis, the heterotrophic flagellate Oxyrrhismarina and the copepod Acartia tonsa, calcite dissolution rates of 4555%, 3753%and 522% of ingested calcite were found. We ascribe higher loss rates in microzoo10plankton food vacuoles as compared to copepod guts to the strongly acidic digestionand the individual packaging of algal cells. In further experiments, specific rates ofcalcification and calcite dissolution were also measured in natural populations duringthe PeECE III mesocosm study under differing ambient pCO2 concentrations. Microzooplanktongrazing accounted for between 27 and 70% of the dynamic calcite stock15 being lost per day, with no measurable effect of CO2 treatment. These measured calcitedissolution rates indicate that dissolution of calcite in the guts of microzooplanktonand copepods can account for the calcite losses calculated for the global ocean usingbudget and model estimates. |
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