Publication Date:
2017-05-19
Description:
Climate-driven changes in environmental conditions have significant and complex effects on marine ecosystems. Variability in phytoplankton elements and biochemicals can be important for global ocean biogeochemistry and ecological functions, while there is currently limited understanding on how elemental stoichiometry and biochemicals respond to the changing environments in key coccolithophore species such as Emiliania huxleyi. We investigated responses of stoichiometric C : N : P ratios, PIC : POC contents and ratios, and fatty acid (FA) composition in a strain of E. huxleyi under three temperatures (12, 18 and 24 °C), three N : P supply ratios (10 : 1, 24 : 1 and 63 : 1 mol mol−1) and two pCO2 levels (560 and 2400 µatm). Overall, C : N : P biomass ratios showed the most pronounced response to N : P supply ratios, with low N : C and N : P biomass ratios in low N-media, and low P : C and high N : P biomass ratios in low P-media. PIC : POC ratios and polyunsaturated FA proportions strongly responded to temperature and pCO2, both being lower under high pCO2 and higher with warming. We observed synergistic interactions between warming and nutrient deficiency (and high pCO2) on PIC and POC cellular contents in most cases, indicating the enhanced effect of warming on E. huxleyi calcification and photosynthesis under nutrient deficiency (and high pCO2). Our results suggest differential sensitivity of elements and FAs to the changes in temperature, nutrient availability and pCO2 in E. huxleyi, which is to some extent unique compared with non-calcifying algal classes. Thus, simultaneous changes of elements and FAs should be considered when predicting future roles of E. huxleyi in the biotic-mediated connection between biogeochemical cycles, ecological functions and climate change.
Print ISSN:
1810-6277
Electronic ISSN:
1810-6285
Topics:
Biology
,
Geosciences
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