Reference : Transparent exopolymer particles and dissolved organic carbon production by Emiliania...
Scientific journals : Article
Life sciences : Microbiology
Life sciences : Aquatic sciences & oceanology
Life sciences : Environmental sciences & ecology
Transparent exopolymer particles and dissolved organic carbon production by Emiliania huxleyi exposed to different CO2 concentrations: a mesocosm experiment
Engel, Anja [Alfred Wegener Institute for Polar- and Marine Research]
Delille, Bruno mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique >]
Jacquet, Stéphan [UMR CARRTEL > Station INRA d’Hydrobiologie Lacustre]
Riebesell, Ulf [Alfred Wegener Institute for Polar- and Marine Research]
Rochelle-Newall, Emma [Laboratoire d’Océanographie de Villefranche-sur-Mer]
Terbrüggen, Anja [Alfred Wegener Institute for Polar- and Marine Research]
Zondervan, Ingrid [Alfred Wegener Institute for Polar- and Marine Research]
Aquatic Microbial Ecology
Oldendorf Luhe
[en] Emiliana huxleyi ; transparent exopolymer particles ; TEP ; dissolved organic carbon ; DOC ; carbon overconsumption ; CO2 ; Redfield ratios ; mesocosms
[en] The role of transparent exopolymer particles (TEP) and dissolved organic carbon (DOC) for organic carbon partitioning under different CO2 conditions was examined during a mesocosm experiment with the coccolithophorid Emiliania huxleyi. We designed 9 outdoor enclosures (similar to11 m(3)) to simulate CO2 concentrations of estimated 'Year 2100' (similar to710 ppm CO2), 'present' (similar to410 ppm CO2) and 'glacial' (similar to190 ppm CO2) environments, and fertilized these with nitrate and phosphate to favor bloom development. Our results showed fundamentally different TEP and DOC dynamics during the bloom. In all mesocosms, TEP concentration increased after nutrient exhaustion and accumulated steadily until the end of the study. TEP concentration was closely related to the abundance of E. huxleyi and accounted for an increase in POC concentration of 35 +/- 2 % after the onset of nutrient limitation. The production of TEP normalized to the cell Abundance of E. huxleyi was highest in the Year 2100 treatment. In contrast, DOC concentration exhibited considerable short-term fluctuations throughout the study. In all mesocosms, DOC was neither related to the abundance of E. huxleyi nor to TEP concentration. A statistically significant effect of the CO2 treatment on DOC concentration was not determined. However, during the course of the bloom, DOC concentration increased in 2 of the 3 Year 2100 mesocosms and in 1 of the present mesocosms, but in none of the glacial mesocosms. It is suggested that the observed differences between TEP and DOC were determined by their different bioavailability and that a rapid response of the microbial food web may have obscured CO2 effects on DOC production by autotrophic cells.
University of Bergen ; Commission européenne : Direction générale de la Recherche
European Commission Human Potential Programm No.HPRI-1999-0056
Copyright Inter-Research 2004 · Resale or republication not permitted without written consent of the publisher

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