Combined effects of CO2 and temperature on carbon uptake and partitioning by the marine diatoms Thalassiosira weissflogii and Dactyliosolen fragilissimus.

Taucher, Jan , Jones, J., James, A., Brzezinski, M. A., Carlson, C. A., Riebesell, Ulf and Passow, U. (2015) Combined effects of CO2 and temperature on carbon uptake and partitioning by the marine diatoms Thalassiosira weissflogii and Dactyliosolen fragilissimus. Open Access Limnology and Oceanography, 60 (3). pp. 901-919. DOI 10.1002/lno.10063.

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Abstract

Carbon uptake and partitioning of two globally abundant diatom species, Thalassiosira weissflogii and Dactyliosolen fragilissimus, was investigated in batch culture experiments under four conditions: ambient (15 degrees C, 400 atm), high CO2 (15 degrees C, 1000 atm), high temperature (20 degrees C, 400 atm), and combined (20 degrees C, 1000 atm). The experiments were run from exponential growth into the stationary phase (six days after nitrogen depletion), allowing us to track biogeochemical dynamics analogous to bloom situations in the ocean. Elevated CO2 had a fertilizing effect and enhanced uptake of dissolved inorganic carbon (DIC) by about 8% for T. weissflogii and by up to 39% for D. fragilissimus. This was also reflected in higher cell numbers, build-up of particulate and dissolved organic matter, and transparent exopolymer particles. The CO2 effects were most prominent in the stationary phase when nitrogen was depleted and CO2(aq) concentrations were low. This indicates that diatoms in the high CO2 treatments could take up more DIC until CO2 concentrations in seawater became so low that carbon limitation occurs. These results suggest that, contrary to common assumptions, diatoms could be highly sensitive to ongoing changes in oceanic carbonate chemistry, particularly under nutrient limitation. Warming from 15 to 20 degrees C had a stimulating effect on one species but acted as a stressor on the other species, highlighting the importance of species-specific physiological optima and temperature ranges in the response to ocean warming. Overall, these sensitivities to CO2 and temperature could have profound impacts on diatoms blooms and the biological pump.

Document Type: Article
Additional Information: WOS:000354490100014
Keywords: TRANSPARENT EXOPOLYMER PARTICLES; DISSOLVED ORGANIC-CARBON; COCCOLITHOPHORE EMILIANIA-HUXLEYI; NET COMMUNITY PRODUCTION; C-N RATIO; CONCENTRATING MECHANISMS; PHYTOPLANKTON GROWTH; CHEMICAL-COMPOSITION; OCEAN ACIDIFICATION; MESOCOSM EXPERIMENT
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BM Biogeochemical Modeling
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BI Biological Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1002/lno.10063
ISSN: 0024-3590
Date Deposited: 17 Jun 2015 08:59
Last Modified: 01 Jun 2018 23:38
URI: http://oceanrep.geomar.de/id/eprint/28992

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