Picophytoplankton size and biomass around equatorial eastern Indian Ocean

Wei, Yuqiu; Sun, Jun; Zhang, Xiaodong; Wang, Jing; Huang, Ke

doi:10.1002/mbo3.629

Cited by 35 publications

(25 citation statements)

References 59 publications

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“…Surface waters showed persistently high stratification, limiting the availability of DIN and DIP, which resulted in low phytoplankton biomass for most of the year (Figs. 1F and 2) and a clear dominance of small cells consistent with previous work (Bock et al, 2018;Van den Engh et al, 2017;Wei et al, 2019). Accordingly, DOC concentrations did not exceed 95 µmol L −1 .…”

Section: Discussionsupporting

confidence: 90%

Seasonal variability and vertical distribution of autotrophic and heterotrophic picoplankton in the Central Red Sea

Al-Otaibi

Huete‐Stauffer

Calleja

et al. 2020

PeerJ

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The Red Sea is characterized by higher temperatures and salinities than other oligotrophic tropical regions. Here, we investigated the vertical and seasonal variations in the abundance and biomass of autotrophic and heterotrophic picoplankton. Using flow cytometry, we consistently observed five groups of autotrophs (Prochlorococcus, two populations of Synechococcus separated by their relative phycoerythrin fluorescence, low (LF-Syn) and high (HF-Syn), and two differently-sized groups of picoeukaryotes, small (Speuk) and large (Lpeuk)) and two groups of heterotrophic prokaryotes of low and high nucleic acid content (LNA and HNA, respectively). Samples were collected in 15 surveys conducted from 2015 to 2017 at a 700-m depth station in the central Red Sea. Surface temperature ranged from 24.6 to 32.6 °C with a constant value of 21.7 °C below 200 m. Integrated (0–100 m) chlorophyll a concentrations were low, with maximum values in fall (24.0 ± 2.7 mg m−2) and minima in spring and summer (16.1 ± 1.9 and 1.1 mg m−2, respectively). Picoplankton abundance was generally lower than in other tropical environments. Vertical distributions differed for each group, with Synechococcus and LNA prokaryotes more abundant at the surface while Prochlorococcus, picoeukaryotes and HNA prokaryotes peaked at the deep chlorophyll maximum, located between 40 and 76 m. Surface to 100 m depth-weighted abundances exhibited clear seasonal patterns for Prochlorococcus, with maxima in summer (7.83 × 104 cells mL−1, July 2015) and minima in winter (1.39 × 104 cells mL−1, January 2015). LF-Syn (0.32 – 2.70 × 104 cells mL−1 ), HF-Syn (1.11 – 3.20 × 104 cells mL−1) and Speuk (0.99 – 4.81 × 102 cells mL−1) showed an inverse pattern to Prochlorococcus, while Lpeuk (0.16 – 7.05 × 104 cells mL−1) peaked in fall. Synechococcus unexpectedly outnumbered Prochlorococcus in winter and at the end of fall. The seasonality of heterotrophic prokaryotes (2.29 – 4.21×105 cells mL−1 ) was less noticeable than autotrophic picoplankton. The contribution of HNA cells was generally low in the upper layers, ranging from 36% in late spring and early summer to ca. 50% in winter and fall. Autotrophs dominated integrated picoplankton biomass in the upper 100 m, with 1.4-fold higher values in summer than in winter (mean 387 and 272 mg C m–2, respectively). However, when the whole water column was considered, the biomass of heterotrophic prokaryotes exceeded that of autotrophic picoplankton with an average of 411 mg C m–2. Despite being located in tropical waters, our results show that the picoplankton community seasonal differences in the central Red Sea are not fundamentally different from higher latitude regions.

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Section: Discussionsupporting

confidence: 90%

Seasonal variability and vertical distribution of autotrophic and heterotrophic picoplankton in the Central Red Sea

Al-Otaibi

Huete‐Stauffer

Calleja

et al. 2020

PeerJ

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show abstract

“…Surface waters showed persistently high stratification, limiting the availability of DIN and DIP, which resulted in low phytoplankton biomass for most of the year (Fig. 1F and 2) and a clear dominance of small cells consistent with previous work (Bock et al 2018;van den Engh et al 2017;Wei et al 2019). Accordingly, DOC concentrations did not exceed 95 µmol L -1 .…”

Section: Discussionsupporting

confidence: 87%

“…7), suggesting that the upper central Red Sea would be a net autotrophic ecosystem over the entire annual cycle (i.e., primary production would exceed community respiration), in agreement with the recent study of López-Sandoval et al (2019). The major contributor to autotrophic picoplankton biomass was Prochlorococcus as in other oligotrophic waters (Wei et al 2019;Zhang et al 2008), except in winter. However, if we extend the comparison between autotrophic and heterotrophic picoplankton biomass to the bottom of the study site, the ecosystem would then tend to net heterotrophic, but this difference was not very marked (Fig.…”

Section: Seasonal Variation Of Picoplanktonmentioning

confidence: 91%

Peer Review #3 of "Seasonal variability and vertical distribution of autotrophic and heterotrophic picoplankton in the Central Red Sea (v0.1)"

2020

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The Red Sea is characterized by higher temperatures and salinities than other oligotrophic tropical regions. Here, we investigated the vertical and seasonal variations in the abundance and biomass of autotrophic and heterotrophic picoplankton. Using flow cytometry, we consistently observed five groups of autotrophs [Prochlorococcus, two populations of Synechococcus separated by their relative phycoerythrin fluorescence, low (LF-Syn) and high (HF-Syn), and two differently-sized groups of picoeukaryotes, small (Speuk) and large (Lpeuk)] and two groups of heterotrophic prokaryotes of low and high nucleic acid content (LNA and HNA, respectively). Samples were collected in 15 surveys conducted from 2015 to 2017 at a 700-m depth station in the central Red Sea. Surface temperature ranged from 24.6 to 32.6°C with a constant value of 21.7°C below 200 m. Integrated (0-100 m) chlorophyll a concentrations were low, with maximum values in fall (24.0 ± 2.7 mg m-2) and minima in spring and summer (16.1 ± 1.9 and 1.1 mg m-2 , respectively). Picoplankton abundance was generally lower than in other tropical environments. Vertical distributions differed for each group, with Synechococcus and LNA prokaryotes more abundant at the surface while Prochlorococcus, picoeukaryotes and HNA prokaryotes peaked at the deep chlorophyll maximum, located between 40 and 76 m. Surface to 100 m depth-weighted abundances exhibited clear seasonal patterns for Prochlorococcus, with maxima in summer (7.83 × 10 4 cell mL-1 , July 2015) and minima in winter (1.39 × 10 4 cell mL-1 , January 2015). LF-Syn (0.32-2.70 × 10 4 cell mL-1), HF-Syn (1.11-3.20 × 10 4 cell mL-1) and Speuk (0.99-4.81 × 10 2 cell mL-1) showed an inverse pattern to Prochlorococcus, while Lpeuk (0.16-7.05 × 10 4 cell mL-1) peaked in fall. Synechococcus unexpectedly outnumbered Prochlorococcus in winter and at the end of fall. The seasonality of heterotrophic prokaryotes (2.29-4.21× 10 5 cell mL-1) was less noticeable than autotrophic picoplankton. The contribution of HNA cells was generally low in the upper layers, ranging from 36% in late spring and early summer to ca. 48-51% in winter and fall. Autotrophs dominated integrated picoplankton biomass in the upper 100 m, with 1.4-fold higher values in summer than in winter (mean 387 and 272 mg C m-2 , respectively). However, when the whole water column was considered, the biomass of heterotrophic prokaryotes exceeded that of autotrophic picoplankton with an average of 411 mg C m-2. Despite being located in tropical waters, our results show that the picoplankton community seasonal differences in the central Red Sea are not fundamentally different from higher latitude regions.

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“…Although Ribeiro et al (2016) suggested that the low concentrations of photosynthetic pigments in Pro cells in surface waters may lead to an underestimation of abundance by the BD Accuri FCM, the average Pro abundances observed in the 3 contrasting seas are of the same magnitude as previous studies in other marine ecosystems (e.g. Flombaum et al 2013, van den Engh et al 2017, Wei et al 2019a, Zhao et al 2019. In addition, Pro cells in deeper waters containing relatively higher concentrations of pigments have allowed better detection on the BD Accuri FCM (Ribeiro et al 2016); thus, this underestimation does not affect the spatial distribution patterns of abundance and biomass for Pro demonstrated herein (Bergo et al 2017).…”

Section: Abundance Spatial Distribution and Associated Environmentalmentioning

confidence: 70%

“…Collectively, Pro are most abundant in the oligotrophic open waters, but they are by no means restricted to this habitat. In addition, light, water turbidity and disturbance, competition among groups, ecotype succession and grazing pressure are all important controlling factors (Landry et al 2003, Grébert et al 2018, Wei et al 2019a. The partial increase in nutrient availability particularly in the oligotrophic open oceans can also stimulate the Pro growth (discussed below), indicating that some undiscovered factors may also influence the biogeographic variations of picophytoplankton at the global scale.…”

Section: Abundance Spatial Distribution and Associated Environmentalmentioning

confidence: 99%

Biogeographic variations of picophytoplankton in three contrasting seas: the Bay of Bengal, South China Sea and Western Pacific Ocean

Wei

Huang

Zhang

et al. 2020

Aquat. Microb. Ecol.

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Marine picophytoplankton are abundant in many oligotrophic oceans, but the known geographical patterns of picophytoplankton are primarily based on small-scale cruises or time-series observations. Here, we conducted a wider survey (5 cruises) in the Bay of Bengal (BOB), South China Sea (SCS) and Western Pacific Ocean (WPO) to better understand the biogeographic variations of picophytoplankton. Prochlorococcus (Pro) were the most abundant picophytoplankton (averaging [1.9-3.6] × 104 cells ml-1) across the 3 seas, while average abundances of Synechococcus (Syn) and picoeukaryotes (PEuks) were generally 1-2 orders of magnitude lower than Pro. Average abundances of total picophytoplankton were similar between the BOB and SCS (4.7 × 104 cells ml-1), but were close to 2-fold less abundant in the WPO (2.5 × 104 cells ml-1). Pro and Syn accounted for a substantial fraction of total picophytoplankton biomass (70-83%) in the 3 contrasting seas, indicating the ecological importance of Pro and Syn as primary producers. Pro were generally abundant in oligotrophic open waters; however, the exceptional presence of Pro near the SCS coast was potentially associated with the Kuroshio intrusion. Syn and PEuk abundances were higher near freshwater-dominated areas, which was likely due to dilution waters. Water temperature and cold eddies were also major drivers responsible for the biogeographic distributions of picophytoplankton. Although Pro, Syn and PEuks showed negative correlations with nutrient concentrations, their maximal abundances in vertical distribution showed positive correlations with the nutricline depth, indicating that nutrient availability plays a 2-faceted role in regulating the biogeographic variation in picophytoplankton.

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Picophytoplankton size and biomass around equatorial eastern Indian Ocean

Cited by 35 publications

References 59 publications

Seasonal variability and vertical distribution of autotrophic and heterotrophic picoplankton in the Central Red Sea

Seasonal variability and vertical distribution of autotrophic and heterotrophic picoplankton in the Central Red Sea

Peer Review #3 of "Seasonal variability and vertical distribution of autotrophic and heterotrophic picoplankton in the Central Red Sea (v0.1)"

Biogeographic variations of picophytoplankton in three contrasting seas: the Bay of Bengal, South China Sea and Western Pacific Ocean

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