Why marine phytoplankton calcify

Monteiro, Fanny M.; Bach, Lennart T.; Brownlee, Colin; Bown, Paul R.; Rickaby, Rosalind E. M.; Poulton, Alex J.; Tyrrell, Toby; Beaufort, Luc; Dutkiewicz, Stephanie; Gibbs, Samantha J.; Gutowska, Magdalena A.; Lee, Renee; Riebesell, Ulf; Young, Jeremy R.; Ridgwell, Andy

doi:10.1126/sciadv.1501822

Cited by 224 publications

(234 citation statements)

References 121 publications

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“…4) and more than enough coccoliths to cover two daughter cells. This is evidence that cellular calcification (coccolith production) can proceed uninterrupted despite decreasing nutrient availability, and it indicates that the calcification process has a lower nutrient "cost" compared to cell division processes (Paasche, 1998;Monteiro et al, 2016). This is also illustrated by the dramatic overproduction of coccoliths in E. huxleyi under nutrient limitation (Balch et al, 1993;Paasche, 1998) and supported by the C N evidence from Calcidiscus and Helicosphaera in this study and from Coccolithus in Gibbs et al (2013).…”

Section: Physiological Insights Into Coccosphere Geometrysupporting

confidence: 68%

Physiology regulates the relationship between coccosphere geometry and growth phase in coccolithophores

et al. 2017

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Abstract. Coccolithophores are an abundant phytoplankton group that exhibit remarkable diversity in their biology, ecology and calcitic exoskeletons (coccospheres). Their extensive fossil record is a testament to their important biogeochemical role and is a valuable archive of biotic responses to environmental change stretching back over 200 million years. However, to realise the full potential of this archive for (palaeo-)biology and biogeochemistry requires an understanding of the physiological processes that underpin coccosphere architecture. Using culturing experiments on four modern coccolithophore species (Calcidiscus leptoporus, Calcidiscus quadriperforatus, Helicosphaera carteri and Coccolithus braarudii) from three long-lived families, we investigate how coccosphere architecture responds to shifts from exponential (rapid cell division) to stationary (slowed cell division) growth phases as cell physiology reacts to nutrient depletion. These experiments reveal statistical differences in coccosphere size and the number of coccoliths per cell between these two growth phases, specifically that cells in exponential-phase growth are typically smaller with fewer coccoliths, whereas cells experiencing growth-limiting nutrient depletion have larger coccosphere sizes and greater numbers of coccoliths per cell. Although the exact numbers are species-specific, these growth-phase shifts in coccosphere geometry demonstrate that the core physiological responses of cells to nutrient depletion result in increased coccosphere sizes and coccoliths per cell across four different coccolithophore families (Calcidiscaceae, Coccolithaceae, Isochrysidaceae and Helicosphaeraceae), a representative diversity of this phytoplankton group. Building on this, the direct comparison of coccosphere geometries in modern and fossil coccolithophores enables a proxy for growth phase to be developed that can be used to investigate growth responses to environmental change throughout their long evolutionary history. Our data also show that changes in growth rate and coccoliths per cell associated with growthphase shifts can substantially alter cellular calcite production. Coccosphere geometry is therefore a valuable tool for accessing growth information in the fossil record, providing unprecedented insights into the response of species to environmental change and the potential biogeochemical consequences.

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Section: Physiological Insights Into Coccosphere Geometrysupporting

confidence: 68%

Physiology regulates the relationship between coccosphere geometry and growth phase in coccolithophores

et al. 2017

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“…Protection from UV radiation (Xu et al, 2011), for example, may be relevant as this species grows at high light intensities. Furthermore, the consumption of coccoliths by grazers in addition to organic cell material may decrease overall grazing rates (Monteiro et al, 2016). A decrease in coccolith coverage may therefore constitute a loss in overall fitness of an E. huxleyi population.…”

Section: The Effect Of P Limitation On Carbon Productionmentioning

confidence: 99%

“…As this is the first report of P limitation decreasing coccolith production in E. huxleyi, it would be beneficial to test further strains in a similar setup to observe how common this physiological response is in this species. Ecological benefits of coccoliths are likely to be various (Monteiro et al, 2016). Protection from UV radiation (Xu et al, 2011), for example, may be relevant as this species grows at high light intensities.…”

Section: The Effect Of P Limitation On Carbon Productionmentioning

confidence: 99%

Phosphorus limitation and heat stress decrease calcification in Emiliania huxleyi

et al. 2018

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Abstract. 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 Emiliania huxleyi. Both environmental stressors are related to rising CO 2 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 E. huxleyi. 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 E. huxleyi, 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 2 sequestration by E. huxleyi 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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“…Coccolithophores are planktonic single-celled photoautotrophs mostly in the range of 3-20 µm and characterized by bearing calcite plates (coccoliths) (Monteiro et al, 2016) and represent one of the most abundant and widespread groups of marine eukaryotic phytoplankton (Iglesias-Rodríguez et al, 2002;Litchman et al, 2015). In addition to being important primary producers, coccolithophores contribute most of the calcium carbonate (CaCO 3 ) precipitation in pelagic systems.…”

Section: Introductionmentioning

confidence: 99%

Over-calcified forms of the coccolithophore Emiliania huxleyi in high-CO2 waters are not preadapted to ocean acidification

et al. 2018

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Abstract. Marine multicellular organisms inhabiting waters with natural high fluctuations in pH appear more tolerant to acidification than conspecifics occurring in nearby stable waters, suggesting that environments of fluctuating pH hold genetic reservoirs for adaptation of key groups to ocean acidification (OA). The abundant and cosmopolitan calcifying phytoplankton Emiliania huxleyi exhibits a range of morphotypes with varying degrees of coccolith mineralization. We show that E. huxleyi populations in the naturally acidified upwelling waters of the eastern South Pacific, where pH drops below 7.8 as is predicted for the global surface ocean by the year 2100, are dominated by exceptionally over-calcified morphotypes whose distal coccolith shield can be almost solid calcite. Shifts in morphotype composition of E. huxleyi populations correlate with changes in carbonate system parameters. We tested if these correlations indicate that the hyper-calcified morphotype is adapted to OA. In experimental exposures to present-day vs. future pCO2 (400 vs. 1200 µatm), the over-calcified morphotypes showed the same growth inhibition (−29.1±6.3 %) as moderately calcified morphotypes isolated from non-acidified water (−30.7±8.8 %). Under the high-CO2–low-pH condition, production rates of particulate organic carbon (POC) increased, while production rates of particulate inorganic carbon (PIC) were maintained or decreased slightly (but not significantly), leading to lowered PIC ∕ POC ratios in all strains. There were no consistent correlations of response intensity with strain origin. The high-CO2–low-pH condition affected coccolith morphology equally or more strongly in over-calcified strains compared to moderately calcified strains. High-CO2–low-pH conditions appear not to directly select for exceptionally over-calcified morphotypes over other morphotypes, but perhaps indirectly by ecologically correlated factors. More generally, these results suggest that oceanic planktonic microorganisms, despite their rapid turnover and large population sizes, do not necessarily exhibit adaptations to naturally high-CO2 upwellings, and this ubiquitous coccolithophore may be near the limit of its capacity to adapt to ongoing ocean acidification.

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Why marine phytoplankton calcify

Abstract: Calcification in coccolithophores has high energy demand but brings multiple benefits enabling diversity of ecology and form.

Cited by 224 publications

References 121 publications

Physiology regulates the relationship between coccosphere geometry and growth phase in coccolithophores

Physiology regulates the relationship between coccosphere geometry and growth phase in coccolithophores

Phosphorus limitation and heat stress decrease calcification in <i>Emiliania huxleyi</i>

Over-calcified forms of the coccolithophore <i>Emiliania huxleyi</i> in high-CO<sub>2</sub> waters are not preadapted to ocean acidification

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Why marine phytoplankton calcify

Abstract: Calcification in coccolithophores has high energy demand but brings multiple benefits enabling diversity of ecology and form.

Cited by 224 publications

References 121 publications

Physiology regulates the relationship between coccosphere geometry and growth phase in coccolithophores

Physiology regulates the relationship between coccosphere geometry and growth phase in coccolithophores

Phosphorus limitation and heat stress decrease calcification in &lt;i&gt;Emiliania huxleyi&lt;/i&gt;

Over-calcified forms of the coccolithophore &lt;i&gt;Emiliania huxleyi&lt;/i&gt; in high-CO&lt;sub&gt;2&lt;/sub&gt; waters are not preadapted to ocean acidification

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Phosphorus limitation and heat stress decrease calcification in <i>Emiliania huxleyi</i>

Over-calcified forms of the coccolithophore <i>Emiliania huxleyi</i> in high-CO<sub>2</sub> waters are not preadapted to ocean acidification