Effects of high CO2 treatment on nitrate and ammonium uptake by Ulva lactuca grown in different nutrient regimes
G. Magnusson, C. Larsson and L. Axelsson

The uptake of NO3- and NH4+ by Ulva lactuca was inhibited by 5 KPa CO2in a similar way for algae from different growth conditions. The inhibition was most pronounced for NO3-, it was not related to the low pH of the medium, and the time required for recovery was strongly temperature dependent. This response (with a gradual, temperature dependent, recovery) was principally different from those earlier found for red and brown macroalgae,suggesting that responses to high CO2 conditions might reflect the different physiology of the major algal groups. The photosynthetic inorganic carbon supply in U. lactuca governed by two mechanisms for inorganic carbon entry over the plasmalemma and (at least) one CO2 concentrating mechanism, located at the chloroplast envelope. These mechanisms are known to be regulated in a way that is characteristic for green macroalgae (Axelsson et al., 1995), and may respond to increased CO2 concentrations. The possibility that regulation of any of these mechanisms is involved in the recovery of the nutrient uptake capacity during the high CO2treatment is discussed.

Keywords: Ulva lactuca, Chlorophyta, nutrient, CO2-concentrating, bicarbonate, C/N ratio, CCM.
Contents of this volume Sci. Mar. 60(Suppl.1) : 179-189 Back PDF
Please, send comments to
ICM (CSIC) - Passeig Marítim de la Barceloneta, 37-49. E-08003 Barcelona (Spain)