Simultaneous shifts in elemental stoichiometry and fatty acids of <i>Emiliania huxleyi</i> in response to environmental changes
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 e...
Main Authors: | , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2018-02-01
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Series: | Biogeosciences |
Online Access: | https://www.biogeosciences.net/15/1029/2018/bg-15-1029-2018.pdf |
Summary: | 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 elements and biochemicals respond to the changing
environments in key coccolithophore species such as <i>Emiliania
huxleyi</i>. We investigated responses of elemental stoichiometry and fatty
acids (FAs) in a strain of <i>E. huxleyi</i> under three temperatures (12,
18 and 24 °C), three N : P supply ratios (molar ratios 10:1,
24:1 and 63:1) and two <i>p</i>CO<sub>2</sub> levels (560 and 2400 µatm).
Overall, C : N : P stoichiometry showed the most pronounced response to
N : P supply ratios, with high ratios of particulate organic carbon vs.
particulate organic nitrogen (POC : PON) and low ratios of PON vs.
particulate organic phosphorus (PON : POP) in low-N media, and high
POC : POP and PON : POP in low-P media. The ratio of particulate
inorganic carbon vs. POC (PIC : POC) and polyunsaturated fatty acid
proportions strongly responded to temperature and <i>p</i>CO<sub>2</sub>, both being
lower under high <i>p</i>CO<sub>2</sub> and higher with warming. We observed synergistic
interactions between warming and nutrient deficiency (and high <i>p</i>CO<sub>2</sub>)
on elemental cellular contents and docosahexaenoic acid (DHA) proportion in
most cases, indicating the enhanced effect of warming under nutrient
deficiency (and high <i>p</i>CO<sub>2</sub>). Our results suggest differential
sensitivity of elements and FAs to the changes in temperature, nutrient
availability and <i>p</i>CO<sub>2</sub> in <i>E. huxleyi</i>, which is to some extent
unique compared to non-calcifying algal classes. Thus, simultaneous changes
of elements and FAs should be considered when predicting future roles of
<i>E. huxleyi</i> in the biotic-mediated connection between biogeochemical
cycles, ecological functions and climate change. |
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ISSN: | 1726-4170 1726-4189 |