Carbon biomass, and gross growth rates as estimated from 14C pigment labelling, during photoacclimation in Prochlorococcus CCMP 1378

Cailliau, Caroline; Claustre, Hervé; Vidussi, Francesca; Marie, Dominique; Vaulot, Daniel

doi:10.3354/meps145209

Cited by 54 publications

(33 citation statements)

References 13 publications

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“…This yields median values of carbon content per cell of 25 and 50 fg C/cell in the subtropical gyre and near the California coast, respectively. These estimates are in agreement with direct measurements made on cultures (49 fg/cell) (34). The carbon per cell was multiplied by the estimated daily cell production at the end of the southward transect (near Hawaii) to obtain the mean daily carbon production (0.59 mmol C/m 3 per day).…”

Section: Methodssupporting

confidence: 61%

Light-driven synchrony of Prochlorococcus growth and mortality in the subtropical Pacific gyre

Ribalet

Swalwell

Clayton

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

133

156

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Theoretical studies predict that competition for limited resources reduces biodiversity to the point of ecological instability, whereas strong predator/prey interactions enhance the number of coexisting species and limit fluctuations in abundances. In open ocean ecosystems, competition for low availability of essential nutrients results in relatively few abundant microbial species. The remarkable stability in overall cell abundance of the dominant photosynthetic cyanobacterium Prochlorococcus is assumed to reflect a simple food web structure strongly controlled by grazers and/or viruses. This hypothesized link between stability and ecological interactions, however, has been difficult to test with open ocean microbes because sampling methods commonly have poor temporal and spatial resolution. Here we use continuous techniques on two different winter-time cruises to show that Prochlorococcus cell production and mortality rates are tightly synchronized to the day/night cycle across the subtropical Pacific Ocean. In warmer waters, we observed harmonic oscillations in cell production and mortality rates, with a peak in mortality rate consistently occurring ∼6 h after the peak in cell production. Essentially no cell mortality was observed during daylight. Our results are best explained as a synchronized two-component trophic interaction with the per-capita rates of Prochlorococcus consumption driven either directly by the day/night cycle or indirectly by Prochlorococcus cell production. Light-driven synchrony of food web dynamics in which most of the newly produced Prochlorococcus cells are consumed each night likely enforces ecosystem stability across vast expanses of the open ocean.cyanobacteria | cell division | mortality | flow cytometry | SeaFlow P otential interdependencies between species diversity and ecosystem stability have gained increased focus due to global changes in species distributions and abundances (1). Strong predator-prey interactions are predicted to enhance the number of coexisting species and limit fluctuations in abundances (2, 3), whereas competition for limited resources is predicted to reduce biodiversity, in some instances, to the point of ecological instability (3, 4). Mechanisms underlying ecosystem stability remain challenging to characterize on relevant temporal and spatial scales, in part because few empirical data are available to test these theories.Our focus is on the microbial communities within surface waters of the vast oligotrophic gyre of the north Pacific Subtropical Ocean. Here, competition for low concentrations of essential nutrients is hypothesized to result in relatively few abundant microbial species, typified by their extremely small cell sizes and streamlined genomes (5). The cyanobacterium Prochlorococcus numerically dominates the photosynthetic community in these regions, with a relatively constant cell abundance close to half a billion cells per liter despite a population doubling time of approximately one day (6). Such constant cell numbers are predicted when both...

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Section: Methodssupporting

confidence: 61%

Light-driven synchrony of Prochlorococcus growth and mortality in the subtropical Pacific gyre

Ribalet

Swalwell

Clayton

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

133

156

View full text Add to dashboard Cite

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“…Both Prochlorococcus and picoeukaryotes were spherical, giving conversion factors of 98 and 708 fg C cell ¡1 , respectively. The conversion factor for Prochlorococcus is within the range of calculated estimates (29 and 124 fg C cell ¡1 ) reported in other Weld studies (Partensky et al 1999 and references therein;Zubkov et al 2000;Grob et al 2007), but is higher than an estimate of 49 fg C cell ¡1 measured from laboratory cultures (Cailliau et al 1996). Conversion factors for picoeukaryotes vary substantially due to the broader range of possible cell diameters; however, our estimate is within the range of calculated estimates (530-863 fg C cell ¡1 ) for picoeukaryotes from the PaciWc Ocean (Worden et al 2004) with diameters similar to those determined for this study.…”

Section: Estimation Of Photosynthetic Biomassmentioning

confidence: 55%

Picophytoplankton responses to changing nutrient and light regimes during a bloom

et al. 2009

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The spring bloom in seasonally stratiWed seas is often characterized by a rapid increase in photosynthetic biomass. To clarify how the combined eVects of nutrient and light availability inXuence phytoplankton composition in the oligotrophic Gulf of Aqaba, Red Sea, phytoplankton growth and acclimation responses to various nutrient and light regimes were recorded in three independent bioassays and during a naturally-occurring bloom. We show that picoeukaryotes and Synechococcus maintained a "bloomer" growth strategy, which allowed them to grow quickly when nutrient and light limitation were reversed. During the bloom picoeukaryotes and Synechococcus appeared to have higher P requirements relative to N, and were responsible for the majority of photosynthetic biomass accumulation. Following stratiWcation events, populations limited by light showed rapid photoacclimation (based on analysis of cellular Xuorescence levels and photosystem II photosynthetic eYciency) and community composition shifts without substantial changes in photosynthetic biomass. The traditional interpretation of "bloom" dynamics (i.e., as an increase in photosynthetic biomass) may therefore be conWned to the upper euphotic zone where light is not limiting, while other acclimation processes are more ecologically relevant at depth. Characterizing acclimation processes and growth strategies is important if we are to clarify mechanisms that underlie productivity in oligotrophic regions, which account for approximately half of the global primary production in the ocean. This information is also important for predicting how phytoplankton may respond to global warming-induced oligotrophic ocean expansion.

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“…The factors 49, 250, 671, 2100 and 3498 fg C cell −1 were used to convert Prochlorococcus, Synechococcus, picoeukaryotes, nanocyanobacteria and nanoeukaryotes, respectively (Cailliau et al, 1996;Kana and Glibert, 1987;Campbell and Yentsch, 1989;Karayanni et al, 2005).…”

Section: Flow Cytometry (Fcm) and Carbon Biomassmentioning

confidence: 99%

Distribution of ultraphytoplankton in the western part of the North Pacific subtropical gyre during a strong La Niña condition: relationship with the hydrological conditions

Girault

Arakawa²,

Barani³

et al. 2013

Biogeosciences

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The distribution of ultraphytoplankton was investigated in the western North Pacific Subtropical Gyre (NPSG) during La Niña, a cold phase of El Niño Southern Oscillation (ENSO). Observations were conducted in a north-south transect (33.6–13.25° N) along the 141.5° E meridian in order to study the ultraplankton assemblages in various oligotrophic conditions. Analyses were performed at the single cell level by analytical flow cytometry. Five ultraphytoplankton groups (Prochlorococcus, Synechococcus, picoeukaryotes, nanoeukaryotes and nanocyanobacteria-like) defined by their optical properties were enumerated in three different areas visited during the cruise: the Kuroshio region, the subtropical Pacific gyre and a transition zone between the subtropical Pacific gyre and the Warm pool. Prochlorococcus outnumbered the other photoautotrophs in all the investigated areas. However, in terms of carbon biomass, an increase in the relative contribution of Synechococcus, picoeukaryotes and nanoeukaryotes was observed from the centre of the subtropical gyre to the Kuroshio area. In the Kuroshio region, a peak of abundance of nanoeukaryotes observed at the surface suggested an increase in nutrients likely due to the vicinity of a cold cyclonic eddy. In contrast, in the salinity front along the isohaline 35 and anticyclonic eddy located around 22.83° N, the mainly constant distribution of Prochlorococcus from the surface down to 150 m characterised the dominance by these microorganisms in high salinity and temperature zone. Results suggested that the distribution of nanocyanobacteria-like is also closely linked to the salinity front rather than low phosphate concentration. The maximum abundance of ultraphytoplankton was located above the SubTropical Counter Current (STCC) at depths > 100 m where higher nutrient concentrations were measured. Finally, comparison of the ultraphytoplankton concentrations during El Niño (from the literature) and La Niña (this study) conditions seems to demonstrate that La Niña conditions lead to higher concentrations of Synechococcus in the Subtropical gyre and a lower abundance of Synechococcus in the Kuroshio region. Our results suggest that the west part of NPSG is a complex area, where different water masses, salinity fronts and eddies lead to a heterogeneous distribution of ultraphytoplankton assemblages in the upper layer of the water column

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Carbon biomass, and gross growth rates as estimated from 14C pigment labelling, during photoacclimation in Prochlorococcus CCMP 1378

Cited by 54 publications

References 13 publications

Light-driven synchrony of Prochlorococcus growth and mortality in the subtropical Pacific gyre

Light-driven synchrony of Prochlorococcus growth and mortality in the subtropical Pacific gyre

Picophytoplankton responses to changing nutrient and light regimes during a bloom

Distribution of ultraphytoplankton in the western part of the North Pacific subtropical gyre during a strong La Niña condition: relationship with the hydrological conditions

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