Hydrostatic pressure affects physiology and community structure of marine bacteria during settling to 4000 m: an experimental approach

Grossart, Hans‐Peter; Gust, G.

doi:10.3354/meps08201

Cited by 56 publications

(47 citation statements)

References 32 publications

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“…This contradicts the general belief that colonization is the main mechanism determining the attached microbial community at greater depths (43,48). It is, however, possible that other regulating factors, such as quorum sensing (49), viral infection (50), hydrostatic pressure changes (51)(52)(53), and temperature changes (54), had important influences on the outcome of the internal competition between the microbial groups attached to the aggregates, and it will be interesting to use the present method to address those questions.…”

Section: Discussioncontrasting

confidence: 48%

Colonization in the Photic Zone and Subsequent Changes during Sinking Determine Bacterial Community Composition in Marine Snow

Thiele

Fuchs

Amann

et al. 2015

Appl Environ Microbiol

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Due to sampling difficulties, little is known about microbial communities associated with sinking marine snow in the twilight zone. A drifting sediment trap was equipped with a viscous cryogel and deployed to collect intact marine snow from depths of 100 and 400 m off Cape Blanc (Mauritania). Marine snow aggregates were fixed and washed in situ to prevent changes in microbial community composition and to enable subsequent analysis using catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH). The attached microbial communities collected at 100 m were similar to the free-living community at the depth of the fluorescence maximum (20 m) but different from those at other depths (150, 400, 550, and 700 m). Therefore, the attached microbial community seemed to be "inherited" from that at the fluorescence maximum. The attached microbial community structure at 400 m differed from that of the attached community at 100 m and from that of any free-living community at the tested depths, except that collected near the sediment at 700 m. The differences between the particle-associated communities at 400 m and 100 m appeared to be due to internal changes in the attached microbial community rather than de novo colonization, detachment, or grazing during the sinking of marine snow. The new sampling method presented here will facilitate future investigations into the mechanisms that shape the bacterial community within sinking marine snow, leading to better understanding of the mechanisms which regulate biogeochemical cycling of settling organic matter.T he formation of macroscopic organic aggregates such as marine snow is an important process for the removal of photosynthetically fixed carbon from the surface ocean to the deep sea (1). The export of organic matter is the main driver for the oceanic sequestering of atmospheric carbon dioxide on long time scales (2).Settling marine snow aggregates harbor diverse microbial communities that play an important role in the degradation of the organic compounds and release of dissolved nutrients and organic matter to the water column (3-5). Therefore, the attached microbial communities may play an important role in the regulation of the magnitude and efficiency of the biological carbon pump. However, little is known about bacterial community composition and dynamics within marine snow collected below the depths reached by scuba divers. This is because the fragile nature of marine snow makes the collection of individual, intact marine snow particles nearly impossible.Previous investigations have relied on size fractionation of water samples to observe and compare clustering of free-living bacteria to that of bacteria associated with particles (5-8). These studies observed that the composition of the microbial communities associated with particles differed from that of free-living communities in the surrounding water column. However, other studies have found similarities between the free-living and attached microbial communities (9-11), potentially indicating methodolo...

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Section: Discussioncontrasting

confidence: 48%

Colonization in the Photic Zone and Subsequent Changes during Sinking Determine Bacterial Community Composition in Marine Snow

Thiele

Fuchs

Amann

et al. 2015

Appl Environ Microbiol

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“…Hydrostatic pressure has been suggested to be an important environmental parameter influencing microbial dynamics within aggregates (Tamburini et al, 2003(Tamburini et al, , 2006Grossart and Gust, 2009). Grossart and Gust (2009) showed that increasing hydrostatic pressure at constant temperature reduces bacterial cell size and abundance and can select for species with physiological pressure adaptations. Thus, pressure may also have an effect on microbial turnover of organic matter.…”

Section: Discussionmentioning

confidence: 99%

“…pressure equivalent to 4000 m reduces the abundance, cell size, and activity for some strains, while others seem to have physiological pressure adaptations (Grossart and Gust, 2009;Tamburini et al, 2009;Nagata et al, 2010). Such adaptations might explain observations of living, active, surface-adapted, particle-associated bacteria at 6000 m depth (Eloe et al, 2011).…”

Section: H Iversen and H Ploug: Temperature Effects On Respiratimentioning

confidence: 99%

Temperature effects on carbon-specific respiration rate and sinking velocity of diatom aggregates – potential implications for deep ocean export processes

2013

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Abstract. Most deep ocean carbon flux profiles show low and almost constant fluxes of particulate organic carbon (POC) in the deep ocean. However, the reason for the non-changing POC fluxes at depths is unknown. This study presents direct measurements of formation, degradation, and sinking velocity of diatom aggregates from laboratory studies performed at 15 °C and 4 °C during a three-week experiment. The average carbon-specific respiration rate during the experiment was 0.12 ± 0.03 at 15 °C, and decreased 3.5-fold when the temperature was lowered to 4 °C. No direct influence of temperature on aggregate sinking speed was observed. Using the remineralisation rate measured at 4 °C and an average particle sinking speed of 150 m d−1, calculated carbon fluxes were similar to those collected in deep ocean sediment traps from a global data set, indicating that temperature plays a major role for deep ocean fluxes of POC.

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“…An experimental approach by Grossart and Gust (2009) revealed that hydrostatic pressure changes during the sinking of surface bacteria down to 4,000 m, can generate depth-specific minima and maxima in bacterial numbers. Besides this, there are also several other possible reasons for the variance in the declining trend: Assuming that gel particles are settling, it may reflect the different conditions in the surface ocean at the time of production, as gel particles at different depths do not have the same age.…”

Section: Bacterial Colonizationmentioning

confidence: 99%

Bacterial Colonization and Vertical Distribution of Marine Gel Particles (TEP and CSP) in the Arctic Fram Strait

et al. 2017

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Gel particles-a class of abundant transparent organic particles-have increasingly gathered attention in marine research. Field studies on the bacterial colonization of marine gels however are still scarce. So far, most studies on respective particles have focused on the upper ocean, while little is known on their occurrence in the deep sea. Here, we report on the vertical distribution of the two most common gel particle types, which are polysaccharide-containing transparent exopolymer particles (TEP) and proteinaceous Coomassie stainable particles (CSP), as well as numbers of bacteria attached to gel particles throughout the water column, from the surface ocean down to the bathypelagial (< 3,000 m). Our study was conducted in the Arctic Fram Strait during northern hemispheres' summer in 2015. Besides data on the bacterial colonization of the two gel particle types (TEP and CSP), we present bacterial densities on different gel particle size classes according to 12 different sampling depths at four sampling locations. Gel particles were frequently abundant at all sampled depths, and their concentrations decreased from the euphotic zone to the dark ocean. They were colonized by bacteria at all sampled water depths with risen importance at the deepest water layers, where fractions of bacteria attached to gel particles (%) increased within the total bacterial community. Due to the omnipresent bacterial colonization of gel particles at all sampled depths in our study, we presume that euphotic production of this type of organic matter may affect microbial species distribution within the whole water column in the Fram Strait, down to the deep sea. Our results raise the question if changes in the bacterial community composition and functioning on gel particles occur over depth, which may affect microbial respiration and remineralization rates of respective particles in different water layers.

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Hydrostatic pressure affects physiology and community structure of marine bacteria during settling to 4000 m: an experimental approach

Cited by 56 publications

References 32 publications

Colonization in the Photic Zone and Subsequent Changes during Sinking Determine Bacterial Community Composition in Marine Snow

Colonization in the Photic Zone and Subsequent Changes during Sinking Determine Bacterial Community Composition in Marine Snow

Temperature effects on carbon-specific respiration rate and sinking velocity of diatom aggregates – potential implications for deep ocean export processes

Bacterial Colonization and Vertical Distribution of Marine Gel Particles (TEP and CSP) in the Arctic Fram Strait

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