Bacterial production prevails over photo- and chemosynthesis in a eutrophic tropical lagoon

Signori, Camila Negrão; Felizardo, João Paulo de Sá; Enrich‐Prast, Alex

doi:10.1016/j.ecss.2020.106889

Cited by 10 publications

(3 citation statements)

References 69 publications

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“… 42 Although our survey represents all available measurements in the Amazon River, we found other studies in different aquatic systems where rates vary from nanograms of carbon per hour in lakes. 44 − 46 High rates of DCF were observed in karstic systems, 47 − 49 which could be related to the high concentration of inorganic carbon and reduced compounds in soil and groundwater, creating opportunities for microbial growth using the energetic yields of redox reactions to promote chemosynthesis since HBP was observed at lower rates in these systems. 50 , 51 In river estuaries, turbulent mixing promotes an increase in DCF 47 , 52 , 53 and HBP, 54 − 56 which could also be associated with reduced compounds from bottom sediments meeting oxic surface waters.…”

Section: Resultsmentioning

confidence: 99%

Distinct Non-conservative Behavior of Dissolved Organic Matter after Mixing Solimões/Negro and Amazon/Tapajós River Waters

Harir

Schmitt‐Kopplin

et al. 2023

ACS EST Water

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Positive and negative electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry and 1H NMR revealed major compositional and structural changes of dissolved organic matter (DOM) after mixing two sets of river waters in Amazon confluences: the Solimões and Negro Rivers (S + N) and the Amazon and Tapajós Rivers (A + T). We also studied the effects of water mixing ratios and incubation time on the composition and structure of DOM molecules. NMR spectra demonstrated large-scale structural transformations in the case of S + N mixing, with gain of pure and functionalized aliphatic units and loss of all other structures after 1d incubation. A + T mixing resulted in comparatively minor structural alterations, with a major gain of small aliphatic biomolecular binding motifs. Remarkably, structural alterations from mixing to 1d incubation were in essence reversed from 1d to 5d incubation for both S + N and A + T mixing experiments. Heterotrophic bacterial production (HBP) in endmembers S, N, and S + N mixtures remained near 0.03 μgC L–1 h–1, whereas HBP in A, T, and A + T were about five times higher. High rates of dark carbon fixation took place at S + N mixing in particular. In-depth biogeochemical characterization revealed major distinctions between DOM biogeochemical changes and temporal evolution at these key confluence sites within the Amazon basin.

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Section: Resultsmentioning

confidence: 99%

Distinct Non-conservative Behavior of Dissolved Organic Matter after Mixing Solimões/Negro and Amazon/Tapajós River Waters

Harir

Schmitt‐Kopplin

et al. 2023

ACS EST Water

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“…Li et al (1993) described a mean dark carbon fixation of 2% of the light carbon fixation at the surface and 10% at the DCM for the North Atlantic Ocean. Farías et al (2009) and Signori et al (2020) measured 20.3% and 36% of dark carbon fixation contribution in an upwelling system (off the coast of Chile) and in a lagoon off the coast of Brazil, respectively. Prakash et al (1991) found higher ratios of dark and light 14 C uptake in the subtropical gyres and high southern latitudes (10 -50%) compared to temperate and equatorial regions (≤ 10%) and emphasized how variable the 14 C method for dark fixation can be.…”

Section: Relative Importance Of Microbial Processesmentioning

confidence: 99%

Inorganic carbon assimilation by planktonic community in Santos Basin, Southwestern Atlantic Ocean

Kutner,

Bowman,

Saldanha-Corrêa

et al. 2023

Ocean Coast. Res.

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Primary production is essential in shaping biogeochemical cycles and microbial and ecosystem dynamics. The distribution of chemosynthetic rates in pelagic zones and their participation in the carbon cycle, especially when compared to photosynthetic rates in the Southwestern Atlantic Ocean, are poorly constrained. This study aimed to measure pelagic photo-and chemosynthetic productivity and to analyze their spatial distribution and abiotic drivers. Samples for photosynthesis experiments collected at the surface and deep chlorophyll maximum (DCM) were incubated with 14 C-bicarbonate at eight light levels, simulating in situ conditions. Samples for chemosynthesis experiments were collected throughout the water column, from the surface, DCM, 250 m, 900 m, 1,200 m, and 2,300 m, and were incubated in the dark. Rates were analyzed using statistical tests to verify spatial differences between groups of samples and generalized linear models to identify correlations with environmental variables (temperature, salinity, density, mixed layer depth, dissolved oxygen, nitrite, nitrate, silicate, phosphate, turbidity, CDOM, and phycoerythrin and chlorophyll-a concentrations). Moreover, both processes were integrated from the surface to the DCM and compared at the same stations to determine the relative contribution in the epipelagic zone. The photosynthetic and chemosynthetic rates were, on average, 3.00 ± 3.26 mg C m -3 h -1 and 0.97 ± 1.22 mg C m -3 h -1 , respectively. In most stations, chemosynthesis represented an average of 10.2% of total primary productivity, but surpassed photosynthesis in three experiments (reaching 63.4 -78.8%). Photosynthesis displayed a clear offshore-onshore gradient, along with correlated CDOM concentrations, indicating an autochthonous production of the latter. Chemosynthesis, on the other hand, exhibited high variability and lack of prediction by studied environmental variables, with isolated points of substantially higher activity.

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“…Only a few studies combining chemosynthetic production (herein referred to as dark carbon fixation, DCF) and heterotrophic microbial production (HMP) have been done in the SW Atlantic Ocean. However, these published studies are only related to tropical estuarine systems (Signori et al, 2018;Signori et al, 2020). Thus, there is a need to increase the efforts in studies on these metabolic processes to better understand their impact on biogeochemical cycles as a whole.…”

Section: Introductionmentioning

confidence: 99%

Contribution of chemoautotrophy and heterotrophy to the microbial carbon cycle in the Southwestern Atlantic Ocean

et al. 2022

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Dark carbon fixation (DCF) is a source of new and labile carbon in the deep ocean, while heterotrophic microbial production (HMP) promotes organic matter transfer through the microbial loop. Despite their ecological relevance, there is a scientific gap regarding the estimates of DCF and HMP in the Southwestern Atlantic Ocean. Thus, the aim of this study was to investigate the spatial distribution of DCF and HMP; their relevance to the ocean carbon cycle; their relationship with environmental parameters and amongst themselves on the upper slope of Santos Basin. The samples were collected at three different water depths and sediment layers aboard the R/V Alpha Crucis in November 2019. DCF and HMP rates were measured by 14 C-bicarbonate and 3 H-leucine incorporation, respectively, and incubated in the dark. In the water column, DCF rates varied from 1.51 x 10 1 to 3.24 x 10 2 µg C m -3 h -1 , which were one to two orders of magnitude lower than the HMP rates, from 1.26 x 10 2 to 1.48 x 10 4 µg C m -3 h -1 . In the sediments, the DCF ranged from 1.15 x 10 4 to 1.83 x 10 5 µg C m -3 h -1 , while HMP was one to four orders of magnitude lower, 3.22 x 10 1 to 1.56 x 10 3 µ gC m -3 h -1 . DCF rates were significantly higher in the sediments, due to a higher availability of energy sources than in the oligotrophic water above. The HMP had higher rates in the water column as it is deeply dependent on organic matter derived from photosynthesis. This is the first study to investigate DCF and HMP considering the water column and sediments of the Southwestern Atlantic Ocean, thus contributing to a better understanding of the microbial role in the marine carbon cycle and ecosystem functioning.

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Bacterial production prevails over photo- and chemosynthesis in a eutrophic tropical lagoon

Cited by 10 publications

References 69 publications

Distinct Non-conservative Behavior of Dissolved Organic Matter after Mixing Solimões/Negro and Amazon/Tapajós River Waters

Distinct Non-conservative Behavior of Dissolved Organic Matter after Mixing Solimões/Negro and Amazon/Tapajós River Waters

Inorganic carbon assimilation by planktonic community in Santos Basin, Southwestern Atlantic Ocean

Contribution of chemoautotrophy and heterotrophy to the microbial carbon cycle in the Southwestern Atlantic Ocean

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