Effects of CO2(aq) on the carbon isotopic composition of the seagrass Thalassia testudinum Banks ex Koenig (Hydrocharitaceae)
Durako, M.J.; Sackett, W.M. (1993). Effects of CO2(aq) on the carbon isotopic composition of the seagrass Thalassia testudinum Banks ex Koenig (Hydrocharitaceae). J. Exp. Mar. Biol. Ecol. 169(2): 167-180
In: Journal of Experimental Marine Biology and Ecology. Elsevier: New York. ISSN 0022-0981; e-ISSN 1879-1697, more
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| Keywords |
Chemical compounds > Carbon compounds > Atmospheric gases > Carbon dioxide
Chemical reactions > Photochemical reactions > Photosynthesis > Carbon fixation
Flora > Weeds > Marine organisms > Seaweeds > Sea grass
Isotopes
Isotopes > Carbon isotopes
Photosynthesis
Hydrocharitaceae Jussieu [WoRMS]; Thalassia testudinum K.D.Koenig, 1805 [WoRMS]
Marine/Coastal |
| Authors | | Top |
- Durako, M.J.
- Sackett, W.M.
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| Abstract |
The effects of free CO2 (CO2(aq)) on photosynthetic carbon isotopic fractionation of the seagrass Thalassia testudinum were examined using four marine mesocosms at the University of Rhode Island Marine Ecosystems Research Laboratory (MERL). Seedlings and 1-yr-old plants were cultured without substrate for 57 days in seawater media with unmanipulated CO2(aq) levels and approximately 2X, 4X and 10X equilibrium (i.e. 11 mu m CO2(aq)) levels. Fractionation of stable carbon isotopes generally increased as a function of CO2 (aq)), ranging from 12.1 to 21.0 ppt for the year-old plants and from 8.1 to 15.4% ppt for the seedlings. The larger isotopic fractionation effects exhibited by the year-old plants, as compared to those exhibited by seedlings, may have reflected reduced contributions of isotopically heavy seed reserves. Because of inter-mesocosm pH variability, mean CO2(aq)) levels in the unmanipulated mesocosm were about 15% higher, although mean levels of total dissolved inorganic carbon were about 24% lower, than in the 2X mesocosm. Comparatively larger fractionations exhibited by seedlings and year-old plants in the unmanipulated mesocosm suggest a greater importance for CO2(aq)) and a correspondingly lower relative importance of HCO3- as the initial substrate for carbon fixation in this species. |
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