Interaction of CO2 and light availability on photophysiology of tropical coccollitophorids

Three tropical coccolithophorids (Emiliania huxleyi, Gephyrocapsa oceanica and Ochosphaera sp) were grown at batch culture with CO2 system at two levels of CO2 (385 and 1000 ppm) and two different light dark periods. The aims of this study were 1) To determine calcification rate of three selected calcifying miroalgae (Emiliania huxleyi, Gepherocapsa oceanica and Ochospaera sp) with increasing of CO2 concentration, 2) To assess the adaptation of three selected calcifying miroalgae to changing CO2 concentration and Light and Dark period and 3) to examine bioptic responses of three selected calcifying microalgae on changing in CO2 concentration and L:D periods. Growth rate, particulate organic carbon content, particulate inorganic carbon content, chlorophyll a, cell size, and photosynthetic variables were measured. Organic, inorganic carbon production, photosynthesis and calcification rate were calculated. Three tropical coccolithophorids showed a different response to carbonate chemistry changes and dark and light periods in any of the analyzed parameters. High concentration of CO2 (1000 ppm) decreased significantly growth rate of three calcifying microalgae tested on 14:10 hour light: dark periods. Interestingly, the growth rate of three microalgae tested was not significantly different between two CO2 concentrations where they were illuminated by 24 hours light. Three calcifying microalgae in this study responded significantly in the production of POC to changes in CO2 concentrations and the effect of different light dark periods. There were species-specific response of increasing CO2 concentration and light dark periods on photosynthesis and calcification rate. Our study demonstrated that it is to obtain more complete picture of ocean acidification impacts on marine phytoplankton by designing comprehensive experiment that consider multiple variables and their mutual correlations.

Rukminasari N., Lukman M., Yaqin K. & Suggett D., 2014. Interaction of CO2 and light availability on photophysiology of tropical coccollitophorids. Manuscript, Hasanuddin University, 29 pp. Article.

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