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.

Partitioning of CO2 Incorporation Among Planktonic Microbial Guilds and Estimation of In Situ Specific Growth Rates

2005 ◽  
Vol 50 (2) ◽  
pp. 230-241 ◽  
Author(s):  
Josefina García-Cantizano ◽  
Emilio O. Casamayor ◽  
Josep M. Gasol ◽  
Ricardo Guerrero ◽  
Carlos Pedrós-Alió
Keyword(s):  
Growth Rates ◽  
Specific Growth ◽  
Specific Growth Rates

scholarly journals Heterotrophic Bacterioplankton Growth and Physiological Properties in Red Sea Tropical Shallow Ecosystems With Different Dissolved Organic Matter Sources

2022 ◽  
Vol 12 ◽  
Author(s):  
Luis Silva ◽  
Maria Ll. Calleja ◽  
Tamara M. Huete-Stauffer ◽  
Snjezana Ivetic ◽  
Mohd I. Ansari ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Red Sea ◽  
Growth Rates ◽  
Bacterial Abundance ◽  
Specific Growth ◽  
Physiological Status ◽  
Top Down ◽  
Heterotrophic Bacterioplankton ◽  
Specific Growth Rates

Despite the key role of heterotrophic bacterioplankton in the biogeochemistry of tropical coastal waters, their dynamics have been poorly investigated in relation to the different dissolved organic matter (DOM) pools usually available. In this study we conducted four seasonal incubations of unfiltered and predator-free seawater (Community and Filtered treatment, respectively) at three Red Sea coastal sites characterized by different dominant DOM sources: Seagrass, Mangrove, and Phytoplankton. Bacterial abundance, growth and physiological status were assessed by flow cytometry and community composition by 16S rRNA gene amplicons. The Seagrass site showed the highest initial abundances (6.93 ± 0.30 × 105 cells mL–1), coincident with maximum DOC concentrations (>100 μmol C L–1), while growth rates peaked at the Mangrove site (1.11 ± 0.09 d–1) and were consistently higher in the Filtered treatment. The ratio between the Filtered and Community maximum bacterial abundance (a proxy for top-down control by protistan grazers) showed minimum values at the Seagrass site (1.05 ± 0.05) and maximum at the Phytoplankton site (1.24 ± 0.30), suggesting protistan grazing was higher in open waters, especially in the first half of the year. Since the Mangrove and Seagrass sites shared a similar bacterial diversity, the unexpected lack of bacterial response to predators removal at the latter site should be explained by differences in DOM characteristics. Nitrogen-rich DOM and fluorescent protein-like components were significantly associated with enhanced specific growth rates along the inshore-offshore gradient. Our study confirms the hypotheses that top–down factors control bacterial standing stocks while specific growth rates are bottom-up controlled in representative Red Sea shallow, oligotrophic ecosystems.

scholarly journals Molecular Analysis of theIn SituGrowth Rates of Subsurface Geobacter Species

2012 ◽  
Vol 79 (5) ◽  
pp. 1646-1653 ◽  
Author(s):  
Dawn E. Holmes ◽  
Ludovic Giloteaux ◽  
Melissa Barlett ◽  
Milind A. Chavan ◽  
Jessica A. Smith ◽  
...  
Keyword(s):  
Growth Rates ◽  
Ribosomal Proteins ◽  
Specific Growth ◽  
Expression Patterns ◽  
Transcript Abundance ◽  
Metal Reduction ◽  
Content Type ◽  
Specific Growth Rates ◽  
Dissimilatory Metal Reduction

ABSTRACTMolecular tools that can provide an estimate of thein situgrowth rate ofGeobacterspecies could improve understanding of dissimilatory metal reduction in a diversity of environments. Whole-genome microarray analyses of a subsurface isolate ofGeobacter uraniireducens, grown under a variety of conditions, identified a number of genes that are differentially expressed at different specific growth rates. Expression of two genes encoding ribosomal proteins,rpsCandrplL, was further evaluated with quantitative reverse transcription-PCR (qRT-PCR) in cells with doubling times ranging from 6.56 h to 89.28 h. Transcript abundance ofrpsCcorrelated best (r2= 0.90) with specific growth rates. Therefore, expression patterns ofrpsCwere used to estimate specific growth rates ofGeobacterspecies during anin situuranium bioremediation field experiment in which acetate was added to the groundwater to promote dissimilatory metal reduction. Initially, increased availability of acetate in the groundwater resulted in higher expression ofGeobacter rpsC, and the increase in the number ofGeobactercells estimated with fluorescentin situhybridization compared well with specific growth rates estimated from levels ofin situ rpsCexpression. However, in later phases, cell number increases were substantially lower than predicted fromrpsCtranscript abundance. This change coincided with a bloom of protozoa and increased attachment ofGeobacterspecies to solid phases. These results suggest that monitoringrpsCexpression may better reflect the actual rate thatGeobacterspecies are metabolizing and growing duringin situuranium bioremediation than changes in cell abundance.

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.

Specific growth rates of protozooplankton in the marginal ice zone of the central Barents Sea during spring

2000 ◽  
Vol 80 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Benni Winding Hansen ◽  
Frank Jensen
Keyword(s):  
Food Availability ◽  
Growth Rates ◽  
Barents Sea ◽  
Specific Growth ◽  
Open Water ◽  
Marginal Ice Zone ◽  
Fast Ice ◽  
The Mean ◽  
Specific Growth Rates

Protozooplankton growth was measured by incubation in a walk-in cooling room at 5°C of filtered seawater from six stations on a south–north transect from open water through drift ice and into fast ice in the central Barents Sea (72°30′N–76°32′N). Eight species of naked ciliates, two species of tintinnids, seven species of athecate dinoflagellates and nine species of thecate dinoflagellates grew in the 24 and 48 h bottle incubations. Maximum potential mean specific growth rates of 0.84, 0.59, 0.39 and 0.39 d−1, respectively, indicated a hierarchy in growth rates determined by taxonomic differences where growth of naked ciliates > tintinnids > athecate dinoflagellates > thecate dinoflagellates. The mean±SD in situ temperature (4 to −1.8°C) corrected growth rates (Q10=2.8) for the six stations (0.74±0.31, 0.74±0.16, 0.25±0.16, 0.23±0.27 d−1) also suggested a higher growth for ciliates in comparison to dinoflagellates. Additionally, it revealed that the naked ciliates responded to the increased food availability, whereas this was not the case for all other groups of protozooplankton.

Sign in / Sign up

Export Citation Format

Share Document