scholarly journals Potential competition between marine heterotrophic prokaryotes and autotrophic picoplankton for nitrogen substrates

2021 ◽  
Author(s):  
Wenchao Deng ◽  
Shanlin Wang ◽  
Xianhui Wan ◽  
Zhenzhen Zheng ◽  
Nianzhi Jiao ◽  
...  
Keyword(s):  
Autotrophic Picoplankton ◽  
Potential Competition ◽  
Heterotrophic Prokaryotes

scholarly journals Picoplankton Diel Variability and Estimated Growth Rates in Epipelagic and Mesopelagic Waters of the Central Red Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Najwa Al-Otaibi ◽  
Francisca C. García ◽  
Xosé Anxelu G. Morán
Keyword(s):  
Cell Size ◽  
Red Sea ◽  
Growth Rates ◽  
Specific Growth ◽  
Nucleic Acid Content ◽  
Autotrophic Picoplankton ◽  
Heterotrophic Prokaryotes ◽  
Diel Variability ◽  
Specific Growth Rates

The diel variability of the abundance and cell size of picoplanktonic groups in the central Red Sea was monitored every 2 h in situ on 4 occasions (once per season) from 2015 to 2016. We distinguished Prochlorococcus, low (LF-Syn) and high (HF-Syn) fluorescence Synechococcus, small (Speuk) and large (Lpeuk) picoeukaryotes and two groups of heterotrophic prokaryotes of low (LNA) and high (HNA) nucleic acid content. The diel variability in abundance was less marked than in cell size and more apparent in autotrophs than heterotrophs. Specific growth rates were estimated by an empirical relationship from measurements obtained in bottle incubations of surface and deep samples collected in the winter compared with in situ variations in cell size over 24 h. Autotrophic picoplankton groups generally grew faster (0.23–0.77 d–1) than heterotrophic prokaryotes (0.12–0.50 d–1). Surface to 100 m depth-weighted specific growth rates displayed a clear seasonal pattern for Prochlorococcus, with maxima in winter (0.77 ± 0.07 d–1) and minima in fall (0.52 ± 0.07 d–1). The two groups of Synechococcus peaked in spring, with slightly higher growth rates of LF-Syn (0.57 ± 0.04 d–1) than HF-Syn (0.43 ± 0.04 d–1). Speuk and Lpeuk showed different seasonal patterns, with lower values of the former (0.27 ± 0.02 and 0.37 ± 0.04 d–1, respectively). HNA consistently outgrew LNA heterotrophic prokaryotes, with a higher growth in the epipelagic (0–200 m, 0.36 ± 0.03 d–1) than in the mesopelagic (200–700 m, 0.26 ± 0.03 d–1), while no differences were found for LNA cells (0.19 ± 0.03 d–1 and 0.17 ± 0.02 d–1, respectively). With all data pooled, the mean diel abundances of autotrophic picoplankton in the upper epipelagic and of HNA cells in the epipelagic and mesopelagic layers were significantly correlated with the specific growth rates estimated from cell size variations. Our high-resolution sampling dataset suggests that changes in growth rates underlie the noticeable seasonality of picoplankton recently described in these tropical waters.

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

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8612 ◽  
Author(s):  
Najwa Al-Otaibi ◽  
Tamara M. Huete-Stauffer ◽  
Maria Ll. Calleja ◽  
Xabier Irigoien ◽  
Xosé Anxelu G. Morán
Keyword(s):  
Red Sea ◽  
Early Summer ◽  
Nucleic Acid Content ◽  
Tropical Regions ◽  
Autotrophic Picoplankton ◽  
Tropical Environments ◽  
Vertical Distributions ◽  
Ca 50 ◽  
Heterotrophic Prokaryotes ◽  
Two Populations

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.

Predation of wildlife by free-ranging domestic dogs in Polish hunting grounds and potential competition with the grey wolf

2016 ◽  
Vol 201 ◽  
pp. 1-9 ◽  
Author(s):  
Izabela A. Wierzbowska ◽  
Magdalena Hędrzak ◽  
Barłomiej Popczyk ◽  
Henryk Okarma ◽  
Kevin R. Crooks
Keyword(s):  
Domestic Dogs ◽  
Grey Wolf ◽  
Potential Competition ◽  
Free Ranging

scholarly journals Production of dissolved organic matter by phytoplankton and its uptake by heterotrophic prokaryotes in large tropical lakes

2014 ◽  
Vol 59 (4) ◽  
pp. 1364-1375 ◽  
Author(s):  
Cedric Morana ◽  
Hugo Sarmento ◽  
Jean-Pierre Descy ◽  
Josep M. Gasol ◽  
Alberto V. Borges ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Tropical Lakes ◽  
Heterotrophic Prokaryotes

Potential Competition

1976 ◽  
Vol 21 (3) ◽  
pp. 485-508
Author(s):  
Robert K. Hood
Keyword(s):  
Potential Competition

Potential competition and the factors influencing banking concentration

1985 ◽  
Vol 2 (2) ◽  
pp. 94-104
Author(s):  
Thomas G. Watkins ◽  
Kenneth R. Spong ◽  
Mark J. Eichholz
Keyword(s):  
Potential Competition ◽  
Factors Influencing ◽  
Banking Concentration
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