Prokaryotic Life in the Deep Ocean's Water Column

Herndl, Gerhard J.; Bayer, Barbara; Baltar, Federico; Reinthaler, Thomas

doi:10.1146/annurev-marine-032122-115655

Cited by 30 publications

(30 citation statements)

References 148 publications

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“…For estimating the ratio between PCD and POC supply, we assembled a large database of prokaryotic 3 H-leucine incorporation measurements in the Atlantic (n = 1,440) and the Pacific (n = 783) 13,[62][63][64][65] . Prokaryotic heterotrophic production (PHP) was calculated using the leucine-to-carbon conversion factor of 1.55 kg C mol −1 leucine 43 and 0.44 kg C mol −1 leucine 42 .…”

Section: Calculating the Potentially Available Poc And Pcdmentioning

confidence: 99%

Limited carbon cycling due to high-pressure effects on the deep-sea microbiome

et al. 2022

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Deep-sea microbial communities are exposed to high-pressure conditions, which has a variable impact on prokaryotes depending on whether they are piezophilic (that is, pressure-loving), piezotolerant or piezosensitive. While it has been suggested that elevated pressures lead to higher community-level metabolic rates, the response of these deep-sea microbial communities to the high-pressure conditions of the deep sea is poorly understood. Based on microbial activity measurements in the major oceanic basins using an in situ microbial incubator, we show that the bulk heterotrophic activity of prokaryotic communities becomes increasingly inhibited at higher hydrostatic pressure. At 4,000 m depth, the bulk heterotrophic prokaryotic activity under in situ hydrostatic pressure was about one-third of that measured in the same community at atmospheric pressure conditions. In the bathypelagic zone—between 1,000 and 4,000 m depth—~85% of the prokaryotic community was piezotolerant and ~5% of the prokaryotic community was piezophilic. Despite piezosensitive-like prokaryotes comprising only ~10% (mainly members of Bacteroidetes, Alteromonas) of the deep-sea prokaryotic community, the more than 100-fold metabolic activity increase of these piezosensitive prokaryotes upon depressurization leads to high apparent bulk metabolic activity. Overall, the heterotrophic prokaryotic activity in the deep sea is likely to be substantially lower than hitherto assumed, with major impacts on the oceanic carbon cycling.

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Section: Calculating the Potentially Available Poc And Pcdmentioning

confidence: 99%

Limited carbon cycling due to high-pressure effects on the deep-sea microbiome

et al. 2022

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“…The scope of our study is also limited to upper 100 m layer, whereas most attenuation of sinking organic matter by bacteria occurs in the mesopelagic zone. Further studies should focus on deep-sea bacterial dynamics using the model results below 100 m and the data sets on deep-ocean prokaryote abundance and metabolic rates (e.g., Herndl et al, 2022 ).…”

Section: Discussionmentioning

confidence: 99%

Projected 21st-century changes in marine heterotrophic bacteria under climate change

Kim

Laufkötter²,

Lovato³

et al. 2023

Front. Microbiol.

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Marine heterotrophic Bacteria (or referred to as bacteria) play an important role in the ocean carbon cycle by utilizing, respiring, and remineralizing organic matter exported from the surface to deep ocean. Here, we investigate the responses of bacteria to climate change using a three-dimensional coupled ocean biogeochemical model with explicit bacterial dynamics as part of the Coupled Model Intercomparison Project Phase 6. First, we assess the credibility of the century-scale projections (2015–2099) of bacterial carbon stock and rates in the upper 100 m layer using skill scores and compilations of the measurements for the contemporary period (1988–2011). Second, we demonstrate that across different climate scenarios, the simulated bacterial biomass trends (2076–2099) are sensitive to the regional trends in temperature and organic carbon stocks. Bacterial carbon biomass declines by 5–10% globally, while it increases by 3–5% in the Southern Ocean where semi-labile dissolved organic carbon (DOC) stocks are relatively low and particle-attached bacteria dominate. While a full analysis of drivers underpinning the simulated changes in all bacterial stock and rates is not possible due to data constraints, we investigate the mechanisms of the changes in DOC uptake rates of free-living bacteria using the first-order Taylor decomposition. The results demonstrate that the increase in semi-labile DOC stocks drives the increase in DOC uptake rates in the Southern Ocean, while the increase in temperature drives the increase in DOC uptake rates in the northern high and low latitudes. Our study provides a systematic analysis of bacteria at global scale and a critical step toward a better understanding of how bacteria affect the functioning of the biological carbon pump and partitioning of organic carbon pools between surface and deep layers.

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“…In fact, evidence exists that bacteria decrease their activity towards the deep dark ocean [ SI Appendix , Fig. S16] (9, 79). As far as we know, dormancy has not been reported in picoeukaryotes (62), which could partially explain the negligible role of homogeneous selection in the assembly of this domain in the deep ocean.…”

Section: Discussionmentioning

confidence: 99%

Global biogeography of the smallest plankton across ocean depths

Junger

Sarmento²,

Giner

et al. 2023

Preprint

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Tiny ocean plankton (picoplankton) are fundamental for the functioning of the biosphere, but the ecological mechanisms shaping their biogeography are partially understood. Comprehending whether these microorganisms are structured by niche vs. neutral processes is highly relevant in the context of global change. The ecological drivers structuring picoplankton communities differ between prokaryotes and minute eukaryotes (picoeukaryotes) in the global surface ocean: while prokaryotic communities are shaped by a balanced combination of dispersal, selection, and drift, picoeukaryotic communities are mainly shaped by dispersal limitation. Yet, whether or not the relative importance of these processes in structuring picoplankton varies as we dive into the deep ocean was unknown. Here we investigate the mechanisms structuring picoplanktonic communities inhabiting different ocean depths. We analyzed 451 samples from the tropical and subtropical global ocean and the Mediterranean Sea covering the epi- (0-200m), meso- (200-1,000m), and bathypelagic (1,000-4,000m) depth zones. We found that selection decreased with depth possibly due to lower habitat heterogeneity. In turn, dispersal limitation increased with depth, possibly due to dispersal barriers such as water masses and bottom topography. Picoplankton β-diversity positively correlated with environmental heterogeneity and water mass variability in both the open-ocean and the Mediterranean Sea. However, this relationship tended to be weaker for picoeukaryotes than for prokaryotes. Community patterns were generally more pronounced in the Mediterranean Sea, probably because of its substantial cross-basin environmental heterogeneity and deep-water isolation. Altogether, we found that different combinations of ecological mechanisms shape the biogeography of the smallest members of the ocean microbiome across ocean depths.

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Prokaryotic Life in the Deep Ocean's Water Column

Cited by 30 publications

References 148 publications

Limited carbon cycling due to high-pressure effects on the deep-sea microbiome

Limited carbon cycling due to high-pressure effects on the deep-sea microbiome

Projected 21st-century changes in marine heterotrophic bacteria under climate change

Global biogeography of the smallest plankton across ocean depths

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