Variable phosphorus uptake rates and allocation across microbial groups in the oligotrophic Gulf of <scp>M</scp>exico

Popendorf, Kimberly J.; Duhamel, Solange

doi:10.1111/1462-2920.12932

Cited by 13 publications

(15 citation statements)

References 85 publications

(130 reference statements)

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“…4 A and B). Both areas are known to be P-depleted (34,35), suggesting that the dominance of this ESTU could be linked to a specific adaptation to P limitation, as confirmed by the inverse correlation of cluster 2 with P concentrations (Fig. 4C) and correlation analyses between IIIA and individual physico-chemical parameters (Fig.…”

Section: Biogeography Of Prochlorococcus Reveals the Occurrence Of Minormentioning

confidence: 64%

Delineating ecologically significant taxonomic units from global patterns of marine picocyanobacteria

Farrant

Doré

Cornejo‐Castillo

et al. 2016

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

169

315

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Prochlorococcus and Synechococcus are the two most abundant and widespread phytoplankton in the global ocean. To better understand the factors controlling their biogeography, a reference database of the high-resolution taxonomic marker petB, encoding cytochrome b 6 , was used to recruit reads out of 109 metagenomes from the Tara Oceans expedition. An unsuspected novel genetic diversity was unveiled within both genera, even for the most abundant and well-characterized clades, and 136 divergent petB sequences were successfully assembled from metagenomic reads, significantly enriching the reference database. We then defined Ecologically Significant Taxonomic Units (ESTUs)-that is, organisms belonging to the same clade and occupying a common oceanic niche. Three major ESTU assemblages were identified along the cruise transect for Prochlorococcus and eight for Synechococcus. Although Prochlorococcus HLIIIA and HLIVA ESTUs codominated in irondepleted areas of the Pacific Ocean, CRD1 and the yet-to-be cultured EnvB were the prevalent Synechococcus clades in this area, with three different CRD1 and EnvB ESTUs occupying distinct ecological niches with regard to iron availability and temperature. Sharp community shifts were also observed over short geographic distances-for example, around the Marquesas Islands or between southern Indian and Atlantic Oceans-pointing to a tight correlation between ESTU assemblages and specific physico-chemical parameters. Together, this study demonstrates that there is a previously overlooked, ecologically meaningful, fine-scale diversity within some currently defined picocyanobacterial ecotypes, bringing novel insights into the ecology, diversity, and biology of the two most abundant phototrophs on Earth. molecular ecology | metagenomics | Tara Oceans | Synechococcus | Prochlorococcus

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Section: Biogeography Of Prochlorococcus Reveals the Occurrence Of Minormentioning

confidence: 64%

Delineating ecologically significant taxonomic units from global patterns of marine picocyanobacteria

Farrant

Doré

Cornejo‐Castillo

et al. 2016

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

169

315

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“…In fact, on average, small eukaryotes represented less than ~ 1% of the total uptake of PO 4 (> 0.2 μ m), equivalent to previous findings in the oligotrophic North Atlantic (Casey et al ; Hartmann et al ). The low contribution of small eukaryotes to total microbial PO 4 uptake is a result of their lower abundance, but also due to their low biovolume‐normalized assimilation rates compared to bacteria and cyanobacteria (Popendorf and Duhamel ). In the present study, we found that cell‐specific PO 4 uptake rates by cyanobacteria were generally lower than by small eukaryote groups, but when normalizing to their respective biovolume, PO 4 uptake by cyanobacteria was ~ 4 ± 1 times larger than by P‐Euk.…”

Section: Discussionmentioning

confidence: 99%

“…In the present study, we found that cell‐specific PO 4 uptake rates by cyanobacteria were generally lower than by small eukaryote groups, but when normalizing to their respective biovolume, PO 4 uptake by cyanobacteria was ~ 4 ± 1 times larger than by P‐Euk. In the PO 4 ‐depleted Gulf of Mexico, Popendorf and Duhamel () found that on a per‐cell basis, P‐Euk presented the highest PO 4 assimilation rates, but biovolume‐normalized heterotrophic bacteria PO 4 assimilation rates were roughly an order of magnitude higher than those of cyanobacteria and P‐Euk. Similarly, in the North Atlantic subtropical gyre, Hartmann et al () found that the biomass‐specific PO 4 uptake rates of small eukaryotes (P‐Euk and NP‐Euk) were only 5–15% of the biomass‐specific rates of bacterioplankton.…”

Section: Discussionmentioning

confidence: 99%

Small pigmented eukaryotes play a major role in carbon cycling in the P‐depleted western subtropical North Atlantic, which may be supported by mixotrophy

Duhamel

Kim

Sprung

et al. 2019

Limnology & Oceanography

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We found that in the phosphate (PO4)‐depleted western subtropical North Atlantic Ocean, small‐sized pigmented eukaryotes (P‐Euk; < 5 μm) play a central role in the carbon (C) cycling. Although P‐Euk were only ~ 5% of the microbial phytoplankton cell abundance, they represented at least two thirds of the microbial phytoplankton C biomass and fixed more CO2 than picocyanobacteria, accounting for roughly half of the volumetric CO2 fixation by the microbial phytoplankton, or a third of the total primary production. Cell‐specific PO4 assimilation rates of P‐Euk and nonpigmented eukaryotes (NP‐Euk; < 5 μm) were generally higher than of picocyanobacteria. However, when normalized to biovolumes, picocyanobacteria assimilated roughly four times more PO4 than small eukaryotes, indicating different strategies to cope with PO4 limitation. Our results underline an imbalance in the CO2 : PO4 uptake rate ratios, which may be explained by phagotrophic predation providing mixotrophic protists with their largest source of PO4. 18S rDNA amplicon sequence analyses suggested that P‐Euk was dominated by members of green algae and dinoflagellates, the latter group commonly mixotrophic, whereas marine alveolates were the dominant NP‐Euk. Bacterivory by P‐Euk (0.9 ± 0.3 bacteria P‐Euk−1 h−1) was comparable to values previously measured in the central North Atlantic, indicating that small mixotrophic eukaryotes likely exhibit similar predatory pressure on bacteria. Interestingly, bacterivory rates were reduced when PO4 was added during experimental incubations, indicating that feeding rate by P‐Euk is regulated by PO4 availability. This may be in response to the higher cost associated with assimilating PO4 by phagocytosis compared to osmotrophy.

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“…Competition between bacteria and phytoplankton for P is a strong driver of biogeochemistry in marine ecosystems (Thingstad et al, 1993(Thingstad et al, , 1996Popendorf and Duhamel, 2015). Previous studies of planktonic P i -uptake have differentiated bacterial and algal P-uptake using different pore-sized filters, for example considering bacterial uptake as from cells less than 0.6 µm and algal uptake from cells greater than 0.6 µm (e.g., Duhamel and Moutin, 2009).…”

Section: The Dynamics Of Phosphate Uptakementioning

confidence: 99%

Seasonal phosphorus and carbon dynamics in a temperate shelf sea (Celtic Sea)

Poulton

Davis

Daniels

et al. 2019

Progress in Oceanography

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Highlights: Seasonal phosphorus uptake and dissolved organic release examined in the Central Celtic Sea  Uptake highest in spring bloom, with biomass-normalised uptake equal in spring and summer  Release high in November and late spring, with efficient P-retention in summer  Strong phytoplankton influence on spring P-uptake, whilst bacteria influential in summer  Relatively C-rich uptake in November and late April, strongly P-rich in summer AbstractThe seasonal cycle of resource availability in shelf seas has a strong selective pressure on phytoplankton diversity and the biogeochemical cycling of key elements, such as carbon (C) and phosphorus (P). Shifts in carbon consumption relative to P availability, via changes in cellular stoichiometry for example, can lead to an apparent 'excess' of carbon production. We made measurements of inorganic P (P i ) uptake, in parallel to C-fixation, by plankton communities in the Central Celtic Sea (NW European Shelf) in spring (April 2015), summer (July 2015) and fall (November 2014). Short-term (<6 h) P i -uptake coupled with dissolved organic phosphorus (DOP) release, in parallel to net (24 h) primary production (NPP), were all measured across an irradiance gradient designed to typify vertically and seasonally varying light conditions. Rates of P i -uptake were highest during spring and lowest in light-limited fall conditions, although biomass-normalised P i -uptake was similar in spring and summer. The release of DOP was highest in November and declined to low levels in July, indicative of efficient utilization and recycling of the low levels of P i available. Examination of turnover times of the different particulate pools, including phytoplankton and bacteria, indicated a differing seasonal influence of autotrophs and heterotrophs in P-dynamics, with summer conditions associated with a strong bacterial influence and early spring with fast growing phytoplankton. These seasonal changes in plankton composition, coupled with changes in resource availability (P i , light) resulted in seasonal changes in the stoichiometry of NPP to P i -uptake (C:P ratio); from relatively C-rich uptake in November and late April, to P-rich uptake in early April and July. Overall these results highlight how the entire plankton community, both autotrophs and heterotrophs, influence the relative uptake of C and P and that any excess C-consumption relative to the P-rich uptake must be balanced by C-rich process such as the heterotrophic remineralisation and/or consumption of organic material.

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Variable phosphorus uptake rates and allocation across microbial groups in the oligotrophic Gulf of Mexico

Cited by 13 publications

References 85 publications

Delineating ecologically significant taxonomic units from global patterns of marine picocyanobacteria

Delineating ecologically significant taxonomic units from global patterns of marine picocyanobacteria

Small pigmented eukaryotes play a major role in carbon cycling in the P‐depleted western subtropical North Atlantic, which may be supported by mixotrophy

Seasonal phosphorus and carbon dynamics in a temperate shelf sea (Celtic Sea)

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