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SHORT- AND LONG-TERM EFFECTS OF ELEVATED CO2 ON PHOTOSYNTHESIS AND RESPIRATION IN THE MARINE MACROALGA HIZIKIA FUSIFORMIS (SARGASSACEAE, PHAEOPHYTA) GROWN AT LOW AND HIGH N SUPPLIES1
Article first published online: 11 FEB 2011
© 2011 Phycological Society of America
Journal of Phycology
Volume 47, Issue 1, pages 87–97, February 2011
How to Cite
Zou, D., Gao, K. and Luo, H. (2011), SHORT- AND LONG-TERM EFFECTS OF ELEVATED CO2 ON PHOTOSYNTHESIS AND RESPIRATION IN THE MARINE MACROALGA HIZIKIA FUSIFORMIS (SARGASSACEAE, PHAEOPHYTA) GROWN AT LOW AND HIGH N SUPPLIES. Journal of Phycology, 47: 87–97. doi: 10.1111/j.1529-8817.2010.00929.x
Received 4 December 2009. Accepted 20 July 2010.
- Issue published online: 18 FEB 2011
- Article first published online: 11 FEB 2011
- brown algae;
- Hizikia fusiformis;
- marine macroalgae;
The short-term and long-term effects of elevated CO2 on photosynthesis and respiration were examined in cultures of the marine brown macroalga Hizikia fusiformis (Harv.) Okamura grown under ambient (375 μL · L−1) and elevated (700 μL · L−1) CO2 concentrations and at low and high N availability. Short-term exposure to CO2 enrichment stimulated photosynthesis, and this stimulation was maintained with prolonged growth at elevated CO2, regardless of the N levels in culture, indicating no down-regulation of photosynthesis with prolonged growth at elevated CO2. However, the photosynthetic rate of low-N-grown H. fusiformis was more responsive to CO2 enrichment than that of high-N-grown algae. Elevation of CO2 concentration increased the value of K1/2(Ci) (the half-saturation constant) for photosynthesis, whereas high N supply lowered it. Neither short-term nor long-term CO2 enrichment had inhibitory effects on respiration rate, irrespective of the N supply, under which the algae were grown. Under high-N growth, the Q10 value of respiration was higher in the elevated-CO2-grown algae than the ambient-CO2-grown algae. Either short- or long-term exposure to CO2 enrichment decreased respiration as a proportion of gross photosynthesis (Pg) in low-N-grown H. fusiformis. It was proposed that in a future world of higher atmospheric CO2 concentration and simultaneous coastal eutrophication, the respiratory carbon flux would be more sensitive to changing temperature.