The ratio of single-turnover to multiple-turnover fluorescence varies predictably with growth rate and cellular chlorophyll in the green alga Dunaliella tertiolecta

Brown, Matthew B.; Penta, W. B.; Jones, Bradley M.; Behrenfeld, M.

doi:10.1007/s11120-018-00612-7

Cited by 7 publications

(6 citation statements)

References 59 publications

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“…There were no significant differences in elemental ratios within these broad diatom groupings between exponential and early-stationary growth phases suggesting that while quotas may change they do so in concert when nutrient limitation is not the reason for reduced growth. This is in contrast to a common explanation of variable cellular stoichiometry called the growth rate hypothesis (Elser et al, 2003;Claquin et al, 2004;Klausmeier et al, 2004), where cells change the allocation of intracellular biochemical resources based upon different growth strategies and/or conditions. Spilling et al (2015), studying another diatom Chaetoceros wighamii grown at low temperatures, observed elemental stoichiometric ratios similar to those presented here for non-nutrient limited cultures in exponential growth phase, but when nutrients limited growth rate, stoichiometric ratios increased.…”

Section: Nutrient Stoichiometric Ratios and Biogeochemical Applicationsmentioning

confidence: 65%

Pumped Up by the Cold: Elemental Quotas and Stoichiometry of Cold-Water Diatoms

et al. 2019

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Phytoplankton cellular elemental quotas are important for evaluating the coupling of nutrient cycles and assessing nutrient limitation in the ocean. While cell element quotas have been shown to vary in response to growth conditions (e.g., light, nutrient supply), an overriding trait is cell size and biovolume. Allometric relationships are lacking data for phytoplankton grown under polar temperature conditions (e.g., <5 • C); limited field data using single-cell stoichiometry measurements have shown polar diatoms may have significantly different allometry versus low-latitude counterparts. In this study, 11 strains of diatoms isolated from sub/polar waters (both Arctic and Antarctic) were grown in batch growth mode. Cellular carbon (C), nitrogen (N), phosphorus (P), silica (Si), cell number and biovolume were measured during mid-exponential and early stationary growth phases. An allometric log-log relationship was observed between cell element quotas and biovolume, although the strain Odontella aurita was consistently an outlier. Including O. aurita resulted in regression slopes for C, N, P, and Si that were lower than values from the reviewed literature of temperate diatoms; excluding O. aurita resulted in regression slopes that were more similar to published values for each element. However, the intercepts of the elemental quotas in the allometric relationships ranged from ∼5-fold to ∼100-fold greater than published values depending upon the element and the growth phase, meaning that the elemental density is significantly higher for diatoms grown at cold temperatures, although the physiological mechanism(s) cannot be resolved in this study. Cellular ratios of C, N, and P were consistent with prior research, but clearly showed the importance of taxonomic variability as all strains of the genus Thalassiosira behaved more similarly to each other than to the other diatom strains tested. Si:C ratios, in contrast, for non-Thalassiosira strains were greater and approached values commonly observed for iron-limited cells. These results show that a different set of allometric scaling equations is needed when considering sub/polar diatoms relative to temperate and tropical diatoms, which will impact regional and global model parameterization. In addition, these results highlight the role of phytoplankton diversity on biogeochemistry, even within the closely aligned families of diatoms.

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Section: Nutrient Stoichiometric Ratios and Biogeochemical Applicationsmentioning

confidence: 65%

Pumped Up by the Cold: Elemental Quotas and Stoichiometry of Cold-Water Diatoms

et al. 2019

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“…It should be noted that the rise in fluorescence is affected not just by the redox state of the PQ pool but also by the relative PQ pool reduction and oxidation rates (Brown et al. 2019). Analysis of the single‐turnover decay phase of our fluorescence data allows for the calculation of the minimum turnover time (τ) of various stages of electron transport.…”

Section: Discussionmentioning

confidence: 99%

“…Variable fluorescence measurements were made on samples from each mixing layer light regime following methods similar to those used in Brown et al. (2019). A culture sample (˜1.5 mL) was placed into a glass cuvette within a Soliense LIFT‐FRR.…”

Section: Methodsmentioning

confidence: 99%

Photoacclimation State of Thalassiosiraweissflogii is not Affected by Changes in Optical Depth Under A Fluctuating Light Regime Simulating Deep Mixing¹

Brown

Milligan

Behrenfeld

2021

Journal of Phycology

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Satellite‐based remote sensing allows for global estimates of phytoplankton primary productivity by converting measurements of ocean color or photon absorption into units of carbon fixation. Models which perform this conversion often require an estimate of phytoplankton photoacclimation state such as the carbon to chlorophyll a ratio (C:Chl). Recently, our group developed a new photoacclimation model that can be applied to models of primary production. The model assumes that the phytoplankton photoacclimation state is not affected by periods of darkness during deep mixing beneath the photic zone, due to reduction in the plastoquinone pool in darkness and the subsequent deactivation of the signal for chlorophyll synthesis. In this study, we tested these assumptions by culturing the marine diatom Thalassiosira weissflogii under fluctuating light conditions simulating three different optical depths with progressively increasing deep mixing periods. The photoacclimation state, measured by the ratio of C:Chl, in T. weissflogii was not affected by changes in the length of simulated deep mixing periods. In addition, analysis of photosynthesis vs. irradiance (PE) curves showed that increases in optical depth caused decreases in both the maximum Chl‐normalized rate of photosynthesis (Pbmax) and in the slope of light‐limited photosynthesis (αb), but had no effect on the half‐saturation irradiance (Ek, another metric of photoacclimation). However, measurements of chlorophyll fluorescence during simulated deep mixing did not support the hypothesis that the PQ pool was reduced during dark periods. Thus, our findings support the use of the photoacclimation model for estimating primary production while suggesting the need for further research into the mechanisms controlling photoacclimation in the upper mixed layer environment of the ocean.

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“…For each sample, 200–300 μ L of culture volume were diluted into 2 mL of 0.2‐ μ m filtered artificial seawater and then measured in a glass cuvette within the LIFT‐FRR. We followed the four‐phase FRR excitation protocol described by Brown et al (2019) and used data from the initial single‐turnover phase to calculate the quantum efficiency of photochemistry ( F v / F m ) as (Maxwell and Johnson 2000):

\frac{F_{v}}{F_{m}} = \frac{((), F_{m} goodbreak- F_{o})}{F_{m}}

…”

Section: Methodsmentioning

confidence: 99%

Physiological and interspecific factors determine diel changes in phytoplankton bio‐optical properties

Baetge,

Halsey,

Graff

et al. 2024

Limnology & Oceanography

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Bio‐optical properties of marine phytoplankton retrieved through satellite remote sensing are used to estimate ocean productivity and carbon cycling. Daily activity of phytoplankton is attuned to the predictable light fluctuations of the diel cycle. Field and laboratory studies have documented diel changes in phytoplankton growth, division, and respiration, carbon and pigment content, cell size, photosynthetic efficiency and rate, and DNA replication and transcription. Many of these physiological changes can alter cellular optical properties and contribute to diel variations in bulk absorption and scattering properties. Consequently, understanding phytoplankton contributions to diel optical cycles is essential for improving algorithms that convert remote sensing data to biological rates and stocks. Here, we describe time‐resolved cellular, photophysiological, and bio‐optical properties for three cultured phytoplankton ranging in cell size from ~ 1 to 6 μm: Ostreococcus lucimarinus, Synechococcus (WH8102), and Thalassiosira pseudonana, all of which can significantly contribute to phytoplankton abundance and/or biomass in the open and coastal ocean. This work is the first to characterize complete diel cycles in absorption and attenuation for O. lucimarinus and backscattering for all these species. Results show that the percent increase from the minimum to maximum values over the diel cycle ranged between ~ 24–121%, ~ 31–235%, and ~ 25–198% for particulate absorption, attenuation, and backscattering, respectively. Diel changes in bio‐optical properties also differed in both timing and magnitude across phytoplankton species, demonstrating the importance of contextualizing remote sensing observations with phytoplankton community composition.

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The ratio of single-turnover to multiple-turnover fluorescence varies predictably with growth rate and cellular chlorophyll in the green alga Dunaliella tertiolecta

Cited by 7 publications

References 59 publications

Pumped Up by the Cold: Elemental Quotas and Stoichiometry of Cold-Water Diatoms

Pumped Up by the Cold: Elemental Quotas and Stoichiometry of Cold-Water Diatoms

Photoacclimation State of Thalassiosiraweissflogii is not Affected by Changes in Optical Depth Under A Fluctuating Light Regime Simulating Deep Mixing¹

Physiological and interspecific factors determine diel changes in phytoplankton bio‐optical properties

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The ratio of single-turnover to multiple-turnover fluorescence varies predictably with growth rate and cellular chlorophyll in the green alga Dunaliella tertiolecta

Cited by 7 publications

References 59 publications

Pumped Up by the Cold: Elemental Quotas and Stoichiometry of Cold-Water Diatoms

Pumped Up by the Cold: Elemental Quotas and Stoichiometry of Cold-Water Diatoms

Photoacclimation State of Thalassiosiraweissflogii is not Affected by Changes in Optical Depth Under A Fluctuating Light Regime Simulating Deep Mixing1

Physiological and interspecific factors determine diel changes in phytoplankton bio‐optical properties

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Photoacclimation State of Thalassiosiraweissflogii is not Affected by Changes in Optical Depth Under A Fluctuating Light Regime Simulating Deep Mixing¹