Response of heterotrophic bacteria, autotrophic picoplankton and heterotrophic nanoflagellates to re-oligotrophication

Data concerning picoplanktonic community composition and abundance in the Central Adriatic Sea are presented in an effort to improve the knowledge of bacterioplankton and autotrophic picoplankton and their seasonal changes. Flow cytometry analyses revealed the presence of two distinct bacteria populations: HNA and LNA cells. HNA cells showed an explicit correlation with viable and actively respiring cells. The study of viability and activity may increase our knowledge of the part that contributes really to the remineralization and bacterial biomass production. Authotrophic picoplankton abundance, especially picocyanobacteria, was strongly influenced by seasonality, indicating that light availability and water temperature are very important regulating factors. In terms of total carbon biomass, the main contribution came from heterotrophic bacteria with a lower contribution from autotrophic picoplankton. CARD-FISH evidenced, within the Eubacteria domain, the dominance of members of the phyla Alphaproteobacteria, with a strong contribution from SAR11clade, followed by Cytophaga-Flavobacterium and Gammaproteobacteria. The bacterial groups detected contributed differently depending when the sample was taken, suggesting possible seasonal patterns. This study documents for the first time picoplankton community composition in the Central Adriatic Sea using two different approaches, FCM and CARD-FISH, and could provide preliminary data for future studies.

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Spatial distribution of picoseston in the Saratov reservoir in summer

Povolzhskiy Journal of Ecology ◽

10.35885/1684-7318-2021-2-176-190 ◽

2021 ◽

pp. 176-190

Author(s):

E. S. Krasnova ◽

M. V. Umanskaya

Keyword(s):

Spatial Distribution ◽

Food Webs ◽

Significant Contribution ◽

Heterotrophic Bacteria ◽

Total Biomass ◽

Total Abundance ◽

Saratov Reservoir ◽

Autotrophic Picoplankton ◽

Upper Volga ◽

Planktonic Food

The structure and spatial distribution of picoseston in the Saratov reservoir in July 2011 and August 2014 are described. On average, the total abundance of cells and particles forming picoseston was 1.87±0.73×106 cells (part.)/mL; and the total biomass of picoseston was 43.8±19.4 µg C/L. During the study period, solitary heterotrophic bacteria and phototrophic picocyanobacteria prevailed in the picoseston of the Saratov reservoir, amounting to 77–100% of its total abundance and biomass. The proportion of picodetrital particles was extremely small (on average, 4.1% of the total biomass of picoseston). The high heterogeneity of picoceston distribution (Cv is 130% and 110% for abundance and biomass, respectively) was found in the Saratov reservoir during the study period. On average, the abundance and biomass of heterotrophic bacterioplaknton and picodetritus at stations of the tributary estuaries were slightly higher than in the riverbed. At the same time, the abundance of picocyanobacteria was higher, and the biomass was lower at the estuarine stations compared to the riverbed ones. The total number of bacterioplankton and autotrophic picoplankton in the Saratov reservoir in 2011 and 2014 corresponded to the mesotrophic level of productivity. Picodetrital particles, in contrast to the Upper Volga and Kama reservoirs, make no significant contribution to the planktonic food webs of the Saratov reservoir, at least during the study period.

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Picoplankton Distribution and Activity in the Deep Waters of the Southern Adriatic Sea

Water ◽

10.3390/w11081655 ◽

2019 ◽

Vol 11 (8) ◽

pp. 1655 ◽

Cited By ~ 5

Author(s):

Danijela Šantić ◽

Vedrana Kovačević ◽

Manuel Bensi ◽

Michele Giani ◽

Ana Vrdoljak Tomaš ◽

...

Keyword(s):

Deep Sea ◽

Large Scale ◽

Heterotrophic Bacteria ◽

Eastern Mediterranean ◽

Environmental Parameters ◽

Anoxygenic Phototrophic Bacteria ◽

Heterotrophic Nanoflagellates ◽

Nucleic Acid Content ◽

Viral Lysis ◽

Deep Waters

Southern Adriatic (Eastern Mediterranean Sea) is a region strongly dominated by large-scale oceanographic processes and local open-ocean dense water formation. In this study, picoplankton biomass, distribution, and activity were examined during two oceanographic cruises and analyzed in relation to environmental parameters and hydrographic conditions comparing pre and post-winter phases (December 2015, April 2016). Picoplankton density with the domination of autotrophic biomasses was higher in the pre-winter phase when significant amounts of picoaoutotrophs were also found in the meso-and bathy-pelagic layers, while Synechococcus dominated the picoautotrophic group. Higher values of bacterial production and domination of High Nucleic Acid content bacteria (HNA bacteria) were found in deep waters, especially during the post-winter phase, suggesting that bacteria can have an active role in the deep-sea environment. Aerobic anoxygenic phototrophic bacteria accounted for a small proportion of total heterotrophic bacteria but contributed up to 4% of bacterial carbon content. Changes in the picoplankton community were mainly driven by nutrient availability, heterotrophic nanoflagellates abundance, and water mass movements and mixing. Our results suggest that autotrophic and heterotrophic members of the picoplankton community are an important carbon source in the food web in the deep-sea, as well as in the epipelagic layer. Besides, viral lysis may affect the activity of the picoplankton community and enrich the water column with dissolved organic carbon.

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Distribution of marine viruses in the Central and South Adriatic Sea

Mediterranean Marine Science ◽

10.12681/mms.911 ◽

2014 ◽

Vol 16 (1) ◽

pp. 65 ◽

Cited By ~ 5

Author(s):

M. ORDULJ ◽

N. KRSTULOVIĆ ◽

D. ŠANTIĆ ◽

S. JOZIĆ ◽

Μ. ŠOLIĆ

Keyword(s):

Heterotrophic Bacteria ◽

Heterotrophic Nanoflagellates ◽

Viral Lysis ◽

Offshore Area ◽

Open Sea ◽

Significant Difference ◽

Marine Viruses ◽

Relationship Of ◽

Bacterial Groups ◽

Number Of Bacteria

The seasonal distribution of marine viruses and their relationship with heterotrophic bacteria in the coastal and offshore area of the central and southern Adriatic were studied. Additionally, the percentage of high (HNA) and low (LNA) nucleic acid bacteria between the total number of bacteria and the distribution of heterotrophic nanoflagellates (HNF) as a major predator of bacteria were studied as well. The viral abundance ranged from 3.55 to 27.32 × 106 virus-like particles mL-1, and was on average 25-fold higher than bacterial abundances at all investigated stations. The highest viral abundances were found at coastal stations, especially in the area influenced by the rivers Krka and Jadro, whereas the lowest values were found in the open sea and in the coastal area of the southern Adriatic. No significant difference in relationship of viruses with HNA and LNA bacterial groups were established. The ratio between viruses and bacteria (VBR) was higher during the colder part of the year, which coincided with lower HNF abundance and vice versa during the warmer part of the year. This suggests that HNF grazing could be more important in controlling bacterial abundance during the warmer part of the year, and viral lysis during the colder part of the year.

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Multivariate control of heterotrophic bacterial abundance and zooplankton grazing in Labrador fjords (northeastern Canada)

Aquatic Microbial Ecology ◽

10.3354/ame01929 ◽

2020 ◽

Vol 84 ◽

pp. 105-120

Author(s):

AG Simo-Matchim ◽

M Gosselin ◽

C Belzile

Keyword(s):

Growth Rate ◽

Heterotrophic Bacteria ◽

Abiotic Factors ◽

Mean Value ◽

Phytoplankton Growth ◽

Heterotrophic Nanoflagellates ◽

Organic Substrates ◽

Bacterial Growth Rate ◽

Phytoplankton Growth Rate ◽

Substantial Control

This study was conducted in 4 Labrador fjords (Nachvak, Saglek, Okak, and Anaktalak) during the summers of 2007 and 2013, early fall 2010, and late fall 2009. Our results show that water temperature combined with the availability of nutrients and organic substrates are the main abiotic factors controlling the abundance of heterotrophic bacteria in Labrador fjords. Bacterivory also played a crucial role, with heterotrophic bacteria exerting a significant bottom-up control on the abundance of heterotrophic nanoflagellates (r = 0.35, p < 0.05) and ciliates (r = 0.70, p < 0.01). During summer 2013, the intrinsic phytoplankton growth rate varied between <0 and 0.64 d-1, with a mean value of 0.36 d-1. The herbivory rate was highly variable, ranging from 0.01 to 0.86 d-1, with a mean value of 0.31 d-1. Grazing mortality was 6-fold higher than phytoplankton growth rate. Mean phytoplankton growth and herbivory rates in Labrador fjords were comparable to the Barents and Bering seas. The intrinsic growth rate of total heterotrophic bacteria ranged between <0 and 0.68 d-1, with a mean value of 0.30 d-1. Bacterivory varied from 0.01 to 0.95 d-1, with a mean of 0.30 d-1. Mortality due to grazing was up to 2.3 times higher than total bacterial growth rate. This study improves our understanding of the factors influencing the dynamics of heterotrophic bacteria and indicates that herbivory and bacterivory exert substantial control on microbial communities in Labrador fjords.

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Weekly variations of viruses and heterotrophic nanoflagellates and their potential impact on bacterioplankton in shallow waters of the central Red Sea

FEMS Microbiology Ecology ◽

10.1093/femsec/fiaa033 ◽

2020 ◽

Vol 96 (4) ◽

Cited By ~ 2

Author(s):

Eman I Sabbagh ◽

Tamara M Huete-Stauffer ◽

Maria L l Calleja ◽

Luis Silva ◽

Miguel Viegas ◽

...

Keyword(s):

Nucleic Acid ◽

Red Sea ◽

Acid Content ◽

Temporal Dynamics ◽

Heterotrophic Bacteria ◽

Membrane Integrity ◽

Heterotrophic Nanoflagellates ◽

Nucleic Acid Content ◽

Top Down ◽

The Impact

ABSTRACT Bacterioplankton play a pivotal role in marine ecosystems. However, their temporal dynamics and underlying control mechanisms are poorly understood in tropical regions such as the Red Sea. Here, we assessed the impact of bottom-up (resource availability) and top-down (viruses and heterotrophic nanoflagellates) controls on bacterioplankton abundances by weekly sampling a coastal central Red Sea site in 2017. We monitored microbial abundances by flow cytometry together with a set of environmental variables including temperature, salinity, dissolved organic and inorganic nutrients and chlorophyll a. We distinguished five groups of heterotrophic bacteria depending on their physiological properties relative nucleic acid content, membrane integrity and cell-specific respiratory activity, two groups of Synechococcus cyanobacteria and three groups of viruses. Viruses controlled heterotrophic bacteria for most of the year, as supported by a negative correlation between their respective abundances and a positive one between bacterial mortality rates and mean viral abundances. On the contrary, heterotrophic nanoflagellates abundance covaried with that of heterotrophic bacteria. Heterotrophic nanoflagellates showed preference for larger bacteria from both the high and low nucleic acid content groups. Our results demonstrate that top-down control is fundamental in keeping heterotrophic bacterioplankton abundances low (< 5 × 10 5 cells mL−1) in Red Sea coastal waters.

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Dynamics of picoplankton community from coastal waters to the open sea in the Central Adriatic

Mediterranean Marine Science ◽

10.12681/mms.701 ◽

2013 ◽

Vol 15 (1) ◽

pp. 179 ◽

Cited By ~ 10

Author(s):

D. ŠANTIĆ ◽

S. ŠESTANOVIĆ ◽

M. ŠOLIĆ ◽

N. KRSTULOVIĆ ◽

G. KUŠPILIĆ ◽

...

Keyword(s):

Nucleic Acid ◽

Coastal Waters ◽

Adriatic Sea ◽

Heterotrophic Bacteria ◽

Bacterial Biomass ◽

Late Winter ◽

Seasonal Cycles ◽

Trophic Gradient ◽

Autotrophic Picoplankton ◽

Open Sea

Flow cytometry was used to describe seasonal cycles of Prochlorococcus (Prochl), Synechococcus (Syn), picoeukaryotes and heterotrophic bacteria in the central Adriatic Sea along the trophic gradient from January to December 2010. All picoplankton parameters decreased from eutrophic to oligotrophic areas, while the biomass ratio of bacterial to autotrophic picoplankton showed an increase along the trophic gradient. Bacterial biomass ranged from 5.28 to 21.20 μg C l-1. Increased values were present during warmer seasons with the domination of low nucleic acid (LNA) group of bacteria. The high nucleic acid (HNA) bacterial group dominated during the winter and the spring. Bacterial production ranged from 0.09 -0.45 × 104 cells ml-1 h-1 .At coastal stations increased production was present during the winter and the spring and was more or less uniform at open sea stations. Biomasses of Syn and Prochl ranged from 0.16 to 11.47 µg C-1 l-1 and from 0.01 to 3.08 µg C l-1, respectively. They were elevated during the summer and the autumn at coastal stations and during the late winter at the open sea. Syn biomass always dominated over Prochl participating with 61.6-97.2% in biomass of cyanobacteria. Biomass of picoeukaryotes ranged from 1.21 to 21.85 µg C l-1 and was the highest during the winter. Their biomass notably prevailed in autotrophic picoplankton (APP) biomass over that of picocyanobacteria during the whole year. Autotrophic components (Prochl, Syn and picoeukaryotes) made greater contribution to the picoplankton biomass in mesotrophic and eutrophic areas, while heterotrophic bacteria became more important under oligotrophic conditions.

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Ocean acidification reduces growth and grazing impact of Antarctic heterotrophic nanoflagellates

Biogeosciences ◽

10.5194/bg-17-4153-2020 ◽

2020 ◽

Vol 17 (16) ◽

pp. 4153-4171

Author(s):

Stacy Deppeler ◽

Kai G. Schulz ◽

Alyce Hancock ◽

Penelope Pascoe ◽

John McKinlay ◽

...

Keyword(s):

Ocean Acidification ◽

Food Web ◽

Microbial Communities ◽

Heterotrophic Bacteria ◽

Trophic Levels ◽

Heterotrophic Nanoflagellates ◽

Grazing Impact ◽

Antarctic Marine ◽

Morphological Differences ◽

Organic Matter Recycling

Abstract. High-latitude oceans have been identified as particularly vulnerable to ocean acidification if anthropogenic CO2 emissions continue. Marine microbes are an essential part of the marine food web and are a critical link in biogeochemical processes in the ocean, such as the cycling of nutrients and carbon. Despite this, the response of Antarctic marine microbial communities to ocean acidification is poorly understood. We investigated the effect of increasing fCO2 on the growth of heterotrophic nanoflagellates (HNFs), nano- and picophytoplankton, and prokaryotes (heterotrophic Bacteria and Archaea) in a natural coastal Antarctic marine microbial community from Prydz Bay, East Antarctica. At CO2 levels ≥634 µatm, HNF abundance was reduced, coinciding with increased abundance of picophytoplankton and prokaryotes. This increase in picophytoplankton and prokaryote abundance was likely due to a reduction in top-down control of grazing HNFs. Nanophytoplankton abundance was elevated in the 634 µatm treatment, suggesting that moderate increases in CO2 may stimulate growth. The taxonomic and morphological differences in CO2 tolerance we observed are likely to favour dominance of microbial communities by prokaryotes, nanophytoplankton, and picophytoplankton. Such changes in predator–prey interactions with ocean acidification could have a significant effect on the food web and biogeochemistry in the Southern Ocean, intensifying organic-matter recycling in surface waters; reducing vertical carbon flux; and reducing the quality, quantity, and availability of food for higher trophic levels.

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An experimental study of nanoflagellate bacterivory

Revista de Microbiologia ◽

10.1590/s0001-37141999000400014 ◽

1999 ◽

Vol 30 (4) ◽

pp. 369-372 ◽

Cited By ~ 1

Author(s):

Ana Júlia Fernandes ◽

Hilda de Souza Lima Mesquita

Keyword(s):

Experimental Study ◽

Coastal Waters ◽

Heterotrophic Bacteria ◽

Coastal Ecosystem ◽

Heterotrophic Nanoflagellates ◽

Heterotrophic Nanoflagellate

Heterotrophic nanoflagellate Pseudobodo tremulans (4.8 to 7.0 µm) and heterotrophic bacteria, isolated from coastal waters in Ubatuba, SP, Brazil, were used in experiments to analyze quantitatively the relationships between bacteria and nanoflagellates. The meaning of these results for the role of heterotrophic nanoflagellates in the Ubatuba coastal ecosystem is discussed.

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