Effects of varying growth irradiance and nitrogen sources on calcification and physiological performance of the coccolithophore<i>Gephyrocapsa oceanica</i>grown under nitrogen limitation

Tong, Shanying; Hutchins, David A.; Fu, Fei-Xue; Gao, Kunshan

doi:10.1002/lno.10371

Cited by 18 publications

(18 citation statements)

References 49 publications

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“…A large growth rate difference between NH 4 + and NO 3 − at intermediate irradiances, but not at low or high irradiances, has been observed in several other phytoplankton species (Paasche 1971, Thompson et al 1989Wood & Flynn 1995, Tong et al 2016. This difference can be explained by the maximum growth rate being reached at a lower irradiance when growing on NH 4 + than when growing on NO 3 − (i.e.…”

Section: Discussionmentioning

confidence: 93%

Effects of nitrogen source, concentration, and irradiance on growth rates of two diatoms endemic to northern San Francisco Bay

Berg¹,

Driscoll²,

Hayashi³

et al. 2019

Aquat. Biol.

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Impacts on growth rates from exposure to ammonium (NH 4 +) and nitrate (NO 3 −), at non-limiting concentrations, in combination with irradiances varying from 25 to 600 µmol photons m −2 s −1 were investigated in the pelagic diatom Thalassiosira weisflogii and the benthic diatom Entomoneis paludosa recently isolated from Suisun Bay in northern San Francisco Bay. Growth rates were higher in T. weisflogii (0.76 ± 0.3 d −1) compared with E. paludosa (0.58 ± 0.2 d −1) across all irradiances and nitrogen (N) treatments. Differences in growth rates with N source were regulated by irradiance in both diatoms and were greatest at the intermediate irradiance due to saturation of rates at 85 µmol photons m −2 s −1 when growing on NH 4 + and at 200 µmol photons m −2 s −1 when growing on NO 3 −. Notable physiological differences between these 2 diatoms included a larger range in the quantum yield of photosystem II (F v /F m) and in chlorophyll a per cell as a function of irradiance in T. weissflogii compared with E. paludosa. In addition, a negative interaction of high NH 4 + concentration (1000 µmol l −1) and irradiance (≥200 µmol photons m −2 s −1) was observed on growth rates in E. paludosa that was not evident in T. weissflogii. Differences in physiological parameters of these diatoms are discussed in relation to their distributions and frequency of occurrence in Suisun Bay.

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Section: Discussionmentioning

confidence: 93%

Effects of nitrogen source, concentration, and irradiance on growth rates of two diatoms endemic to northern San Francisco Bay

Berg¹,

Driscoll²,

Hayashi³

et al. 2019

Aquat. Biol.

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“…The interactive effects of elevated CO 2 and UV radiation on non-calcifying marine organism have been extensively reported (Li et al, 2012;Gao et al, 2012). With regard to the calcifying coccolithophore E. huxleyi, OA generally reduces their calcification (thinner coccolith layer) as well as the Cal / Pho ratio, based on a number of indoor laboratory experiments with UV-free light sources (Tong et al, 2018). In the present study, with increasing temperature, we found that there was no significant difference in the Cal / Pho ratios between high and low CO 2 -grown cells under UV radiation at 24 • C. The light intensity used was equivalent to the mean light level in the upper mixed layer (UML) based on time series station (19 • N, 118.5 • E) measurements in the South China Sea.…”

Section: Discussionmentioning

confidence: 99%

Physiological and biochemical responses of <i>Emiliania huxleyi</i> to ocean acidification and warming are modulated by UV radiation

2019

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Abstract. Marine phytoplankton such as bloom-forming, calcite-producing coccolithophores, are naturally exposed to solar ultraviolet radiation (UVR, 280–400 nm) in the ocean's upper mixed layers. Nevertheless, the effects of increasing carbon dioxide (CO2)-induced ocean acidification and warming have rarely been investigated in the presence of UVR. We examined calcification and photosynthetic carbon fixation performance in the most cosmopolitan coccolithophorid, Emiliania huxleyi, grown under high (1000 µatm, HC; pHT: 7.70) and low (400 µatm, LC; pHT: 8.02) CO2 levels, at 15 ∘C, 20 ∘C and 24 ∘C with or without UVR. The HC treatment did not affect photosynthetic carbon fixation at 15 ∘C, but significantly enhanced it with increasing temperature. Exposure to UVR inhibited photosynthesis, with higher inhibition by UVA (320–395 nm) than UVB (295–320 nm), except in the HC and 24 ∘C-grown cells, in which UVB caused more inhibition than UVA. A reduced thickness of the coccolith layer in the HC-grown cells appeared to be responsible for the UV-induced inhibition, and an increased repair rate of UVA-derived damage in the HC–high-temperature grown cells could be responsible for lowered UVA-induced inhibition. While calcification was reduced with elevated CO2 concentration, exposure to UVB or UVA affected the process differentially, with the former inhibiting it and the latter enhancing it. UVA-induced stimulation of calcification was higher in the HC-grown cells at 15 and 20 ∘C, whereas at 24 ∘C observed enhancement was not significant. The calcification to photosynthesis ratio (Cal ∕ Pho ratio) was lower in the HC treatment, and increasing temperature also lowered the value. However, at 20 and 24 ∘C, exposure to UVR significantly increased the Cal ∕ Pho ratio, especially in HC-grown cells, by up to 100 %. This implies that UVR can counteract the negative effects of the “greenhouse” treatment on the Cal ∕ Pho ratio; hence, UVR may be a key stressor when considering the impacts of future greenhouse conditions on E. huxleyi.

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“…G. oceanica and many other coccolithophore species (e.g., Helicosphaera carteri, Calcidiscus leptoporus) have larger cell size, higher cellular calcite content and PIC (particulate inorganic carbon) to POC (particulate organic carbon) ratio relative to E. huxleyi, and are known to make large contributions to deep sea calcite fluxes (Daniels, Sheward, & Poulton, 2014;Young & Ziveri, 2000). Despite the important biogeochemical role of G. oceanica in the ocean, its calcification and physiological performance under future environmental change is comparatively poorly understood (Tong, Hutchins, Fu, & Gao, 2016), and its possible long-term evolutionary responses to ocean acidification are completely unknown. There is clearly considerable variation in physiological responses to ocean acidification among different coccolithophore species (Beaufort et al, 2011;Iglesias-Rodriguez et al, 2008;M€ uller, Trull, & Hallegraeff, 2015).…”

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confidence: 99%

Adaptive evolution in the coccolithophore Gephyrocapsa oceanica following 1,000 generations of selection under elevated CO₂

Tong

Gao

Hutchins

2018

Global Change Biology

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Coccolithophores are important oceanic primary producers not only in terms of photosynthesis but also because they produce calcite plates called coccoliths. Ongoing ocean acidification associated with changing seawater carbonate chemistry may impair calcification and other metabolic functions in coccolithophores. While short-term ocean acidification effects on calcification and other properties have been examined in a variety of coccolithophore species, long-term adaptive responses have scarcely been documented, other than for the single species Emiliania huxleyi. Here, we investigated the effects of ocean acidification on another ecologically important coccolithophore species, Gephyrocapsa oceanica, following 1,000 generations of growth under elevated CO 2 conditions (1,000 latm). High CO 2 -selected populations exhibited reduced growth rates and enhanced particulate organic carbon (POC) and nitrogen (PON) production, relative to populations selected under ambient CO 2 (400 latm). Particulate inorganic carbon (PIC) and PIC/POC ratios decreased progressively throughout the selection period in high CO 2 -selected cell lines. All of these trait changes persisted when high CO 2 -grown populations were moved back to ambient CO 2 conditions for about 10 generations. The results suggest that the calcification of some coccolithophores may be more heavily impaired by ocean acidification than previously predicted based on short-term studies, with potentially large implications for the ocean's carbon cycle under accelerating anthropogenic influences.

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Effects of varying growth irradiance and nitrogen sources on calcification and physiological performance of the coccolithophoreGephyrocapsa oceanicagrown under nitrogen limitation

Abstract: Gephyrocapsa oceanica is a widespread species of coccolithophore that has a significant impact on the global carbon cycle through photosynthesis and calcium carbonate precipitation.

Cited by 18 publications

References 49 publications

Effects of nitrogen source, concentration, and irradiance on growth rates of two diatoms endemic to northern San Francisco Bay

Effects of nitrogen source, concentration, and irradiance on growth rates of two diatoms endemic to northern San Francisco Bay

Physiological and biochemical responses of <i>Emiliania huxleyi</i> to ocean acidification and warming are modulated by UV radiation

Adaptive evolution in the coccolithophore Gephyrocapsa oceanica following 1,000 generations of selection under elevated CO₂

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Effects of varying growth irradiance and nitrogen sources on calcification and physiological performance of the coccolithophoreGephyrocapsa oceanicagrown under nitrogen limitation

Abstract: Gephyrocapsa oceanica is a widespread species of coccolithophore that has a significant impact on the global carbon cycle through photosynthesis and calcium carbonate precipitation.

Cited by 18 publications

References 49 publications

Effects of nitrogen source, concentration, and irradiance on growth rates of two diatoms endemic to northern San Francisco Bay

Effects of nitrogen source, concentration, and irradiance on growth rates of two diatoms endemic to northern San Francisco Bay

Physiological and biochemical responses of &lt;i&gt;Emiliania huxleyi&lt;/i&gt; to ocean acidification and warming are modulated by UV radiation

Adaptive evolution in the coccolithophore Gephyrocapsa oceanica following 1,000 generations of selection under elevated CO2

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Physiological and biochemical responses of <i>Emiliania huxleyi</i> to ocean acidification and warming are modulated by UV radiation

Adaptive evolution in the coccolithophore Gephyrocapsa oceanica following 1,000 generations of selection under elevated CO₂