Phosphorus limitation and heat stress decrease calcification in <i>Emiliania huxleyi</i>
Calcifying haptophytes (coccolithophores) sequester carbon in the form of organic and inorganic cellular components (coccoliths). We examined the effect of phosphorus (P) limitation and heat stress on particulate organic and inorganic carbon (calcite) production in the coccolithophore <i>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/15/833/2018/bg-15-833-2018.pdf |
| Summary: | Calcifying haptophytes (coccolithophores) sequester carbon in the
form of organic and inorganic cellular components (coccoliths). We examined
the effect of phosphorus (P) limitation and heat stress on particulate
organic and inorganic carbon (calcite) production in the coccolithophore
<i>Emiliania huxleyi</i>. Both environmental stressors are related to rising CO<sub>2</sub> levels and
affect carbon production in marine microalgae, which in turn impacts
biogeochemical cycling. Using semi-continuous cultures, we show that
P limitation and heat stress decrease the calcification rate in <i>E. huxleyi</i>. However,
using batch cultures, we show that different culturing approaches (batch
versus semi-continuous) induce different physiologies. This affects the
ratio of particulate inorganic (PIC) to organic carbon (POC) and complicates
general predictions on the effect of P limitation on the PIC  ∕  POC ratio. We
found heat stress to increase P requirements in <i>E. huxleyi</i>, possibly leading to lower
standing stocks in a warmer ocean, especially if this is linked to lower
nutrient input. In summary, the predicted rise in global temperature and
resulting decrease in nutrient availability may decrease CO<sub>2</sub>
sequestration by <i>E. huxleyi</i> through lower overall carbon production. Additionally, the
export of carbon may be diminished by a decrease in calcification and a
weaker coccolith ballasting effect. |
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| ISSN: | 1726-4170 1726-4189 |