Organic Particles and Bacteria in the Ocean

Wangersky, Peter J.

doi:10.1007/978-1-4684-9010-7_13

Cited by 6 publications

(4 citation statements)

References 126 publications

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“…comm.). The large volumes of water filtered by salps, and their often inefficient digestion (Pomeroy et al 1984;Wangersky 1984;Gonzalez and Biddanda 1990), result in a concentration of ambient microflora into copious fecal pellets similar to many of those we observed (Matsueda et al 1986). The low assimilation rate of feeding salps (0.8%, Madin 1974) and the large size range over which they feed using a non-specific feeding net (Ͻ1 m to Ͼ1 mm), would explain the wide range of particles we found embedded in the OAs, including individual clusters of prokaryotic and eukaryotic picoplankton, copepod fecal pellets, and microplankton including diatoms and dinoflagellates (Table 1).…”

Section: Discussionmentioning

confidence: 99%

Mass sedimentation of picoplankton embedded in organic aggregates

Waite

Safi

Hall

et al. 2000

Limnology & Oceanography

114

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During a survey cruise crossing the Subtropical Front over the Chatham Rise east of New Zealand, we made the first observation in High Nutrient Low Chlorophyll waters of massive sedimentation of picoplankton embedded in large (Ͼ0.5 mm diam.) organic aggregates (OAs) sensu Riley (1963). We estimate 9.3 mg C m Ϫ2 yr Ϫ1 of prokaryotic picoplankton biomass alone may be transported below the euphotic zone via this mechanism. Using confocal microscopy, we made direct observations of picoplankton within undisrupted individual OAs, collected in sediment traps fitted with acrylimide gels, which largely conserved particle structure. Prokaryotic picoplankton autofluorescence was well-preserved and concentrations were extremely high within large rapidly sedimenting aggregates, ranging from 1.06 ϫ 10 8 ml Ϫ1 in the 120 m sediment traps in subantarctic waters to 7.5 ϫ 10 6 ml Ϫ1 at 550 m in subtropical waters, yielding Enrichment Factors of 10 3 Ϫ105 relative to picoplankton concentrations in the water column. Aggregate picoplankton concentrations showed a well-constrained exponential decline with depth, which we speculate may represent an estimate of protozoan grazing rate within the aggregates. Picoplankton were found within heterotrophic flagellates, within copepod fecal pellets, and within organic matrices, all of which were incorporated in OAs. The key event of picoplankton incorporation into initial particles occurs in the upper water column, very likely through grazing with low assimilation efficiency. Once OAs are formed, their changing porosity and reduction in picoplankton cell numbers via heterotrophy is likely to be a key factor mediating picoplankton carbon fluxes in moderately productive ecosystems, and in determining the overall particle structure of sedimenting OAs.

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Section: Discussionmentioning

confidence: 99%

Mass sedimentation of picoplankton embedded in organic aggregates

Waite

Safi

Hall

et al. 2000

Limnology & Oceanography

114

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“…Much attention has focused on the relative number of these microorganisms that are associated with particulate matter versus those that are free-living ( W~e b e & Pomeroy 1972, Hanson & Wiebe 1977, Hodson e t al. 1981, Ducklow & Kirchman 1983, Smith et al 1986, revicwed by Wangersky 1984). Results vary, but it appears, based on comparisons of data from different investigators working in different waters, that attached bacteria are important in waters where particles are abundant (Wangersky 1984).…”

Section: Introductionmentioning

confidence: 99%

“…1981, Ducklow & Kirchman 1983, Smith et al 1986, revicwed by Wangersky 1984). Results vary, but it appears, based on comparisons of data from different investigators working in different waters, that attached bacteria are important in waters where particles are abundant (Wangersky 1984). In this study we examined the role of free-living bacteria relative to the rest of the planktonic community in coastal waters of the southeastern USA, where the amount of suspended particulate matter varies greatly but predictably.…”

Section: Introductionmentioning

confidence: 99%

Metabolic activity of size-fractionated microbial plankton in estuarine, near-shore, and continental shelf waters of Georgia

Griffith¹,

Douglas²,

Wainright³

1990

Mar. Ecol. Prog. Ser.

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Estimates of bacterial production and activity, and of planktonic community respiration, were made at a series of stations starting in an estuary, passing through the coastal front, and across the continental shelf to a distance of 120 km offshore in the Georgia Bight. Measurements were made on unfiltercd and on 1.0 pm (pore-size) filtered water samples to examine the small free-living bacterial size fraction relative to the larger plankton. In waters landward of the coastal front, ca 50 to 80'70 of bacterial and community activity was associated with the larger size fraction, indicating the importance of larger and particle-associated heterotrophs in the nearshore, hghly turbid water. Seaward of the front, 80 to 99 U/o of activity was in the C 1.0 pm fraction. Thus, the < 1.0 pm size fraction is responsible for most of the respiration in shelf-waters. Bacterial production and activity decreased markedly with distance from shore; community respiration also decreased across the shelf, but not as much as the bactclrial production decreased. Bacterial growth efficiency was low in estuarine waters (11 %), and decreased in nearshore (6 40) and shelf (2 %) waters.

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“…Particle-associated bacteria are often responsible for a substantial fraction of total bacterial metabolism in waters where particles are abundant (1,6,10,16,30,31). When activity is expressed on a per-cell basis, particle-associated bacteria are generally more active than nonattached bacteria (9,15,16,25,28).…”

mentioning

confidence: 99%

Hydrolysis of Protein and Model Dipeptide Substrates by Attached and Nonattached Marine Pseudomonas sp. Strain NCIMB 2021

Griffith

Fletcher

1991

Appl Environ Microbiol

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Rates of substrate hydrolysis by nonattached bacteria and by bacteria attached to particles derived from marine diatom frustules were estimated by using two substrates, a dipeptide analog and a protein. Adsorption of the two substrates onto the particles was also evaluated. Methyl-coumarinyl-amide-leucine (MCA-leucine) was used to estimate hydrolysis of dipeptides by measuring an increase in fluorescence as MCA-leucine was hydrolyzed to leucine and the fluorochrome methylcoumarin. To examine hydrolysis of a larger molecule, we prepared a radiolabeled protein by 14C-methylation of bovine serum albumin. The rate of protein hydrolysis in samples of particle-attached or nonattached bacteria was estimated by precipitating all nonhydrolyzed protein with cold trichloroacetic acid and then determining the trichloroacetic acid-soluble radiolabeled material, which represented methyl-14C-peptides and-amino acids. About 25% of the MCA-leucine adsorbed to the particles. MCA-leucine was hydrolyzed faster by nonattached than attached bacteria, which was probably related to its tendency to remain dissolved in the liquid phase. In contrast, almost 100% of the labeled protein adsorbed to the particles. Accordingly, protein was much less available to nonattached bacteria but was rapidly hydrolyzed by attached bacteria.

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Organic Particles and Bacteria in the Ocean

Cited by 6 publications

References 126 publications

Mass sedimentation of picoplankton embedded in organic aggregates

Mass sedimentation of picoplankton embedded in organic aggregates

Metabolic activity of size-fractionated microbial plankton in estuarine, near-shore, and continental shelf waters of Georgia

Hydrolysis of Protein and Model Dipeptide Substrates by Attached and Nonattached Marine Pseudomonas sp. Strain NCIMB 2021

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