Ciliated protozoa associated with oceanic sinking detritus

Silver, Mary W.; Gowing, Marcia M.; Brownlee, David C.; Corliss, John O.

doi:10.1038/309246a0

Cited by 80 publications

(37 citation statements)

References 12 publications

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“…However, other results are inconsistent with the interpretation that most of the bacteria in these sediment samples originated in shallow water: (1) barophilic bacteria, capable of doubling every 6 h in nutrient broth under i n situ temperature and pressure, were isolated readily from the sediment samples; and (2) enrichment with chitin, rather than yeast extract, induced measurable bacterial growth under in situ temperature and pressure (doubling time of 190 h) in a sediment sample from 1850 m, when no growth was detected at atmospheric pressure, all other conditions being equal. No general conclusions can be drawn from a single chitin-enrichment experiment and no other precedent exists in the literature for bacteria in relatively shallow sediment (1850 m) requiring in situ pressure for optimal growth; nevertheless, the detection of this barophilic growth response argues strongly for the predominant role of locally-adapted bacteria in sediment processes, as has already been proposed for particle-associated processes in the water column at a similar depth (Karl et al 1984, Silver et al 1984. Clearly, detection of this response may also be linked specifically to the remineralization of chitin, a refractory substance commonly available in the deep sea and a substrate of choice for future experiments.…”

Section: Discussionmentioning

confidence: 96%

“…Recent investigations of particulate matter settling through the oceanic water column have revealed subsurface areas of intense microbial activity that is mediated by indigenous bacteria adapted to in situ conditions, and not by surface-derived microorganisms that have settled with the particulates (Fellows et al 1981, Fuhrman & Azam 1983, Gowing & Silver 1983, Karl et al 1984, Silver et al 1984. These findings have extended to about 2000 m, the depth at which in situ microbial activities are known to contribute significantly to the recycling of surface productivity and the nutritional support of aphotic pelagic ecosystems.…”

Section: Introductionmentioning

confidence: 99%

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Bacterial growth in deep-sea sediment trap and boxcore samples

Jiang¹

1985

Mar. Ecol. Prog. Ser.

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This study was to determine whether heterotrophic bacteria associated with deep-sea particulates are adapted more to the moderate temperatures and pressures of surface waters or to the extremes of the deep sea, and how such microorganisms respond to substrate enrichment. Samples of sinking particulates, fecal pellets, and deposited sediments were collected in bottom-moored sediment traps and boxcores at station depths of 1850, 4120, and 4715 m in the North Atlantic. Homogenized seawater suspensions of samples were incubated for 2 to 7 d under both shallow and deep-sea temperatures and pressures, with and without substrate enrichment (yeast extract or chitin). Increases in total bacterial number or percent dividing cells were measured by epifluorescence microscopy. Probable origins of bacteria in a given sample were evaluated according to temperature and pressure regimes affording bacterial growth. With a few exceptions, results indicated a predominance of shallow water bacteria in sediment-trap, but not boxcore, samples and an increasingly significant fraction of deep-sea bactena, adapted to low temperature and elevated pressure, in fecal pellet samples trapped at increasing depth. Under deep-sea conditions, bacterial doubling times in sediment core samples were weeks or months, regardless of substrate enrichment, while in some trap samples were days (>1.5) without enrichment, and hours (7.4 to 14) with enrichment. Doubling times of barophilic bacteria, isolated in pure culture from the deeper trap and core samples, ranged from 6 to 13 h under in situ temperature and pressure. These findings suggest that particulate organic matter, prior to its burial in abyssal sediments, is altered by indigenous, deep-sea bacteria, some of which are capable of rapid activity at low temperature and elevated pressure.

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Section: Discussionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Bacterial growth in deep-sea sediment trap and boxcore samples

Jiang¹

1985

Mar. Ecol. Prog. Ser.

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“…Under these conditions, the biomass, but not growth, of the eucaryotes influences the result. This can make the method inappropriate for measuring production rates in surface waters and other habitats where eucaryotic biomass dominates, such as sinking detritus (Silver et al 1984).…”

Section: Discussionmentioning

confidence: 99%

“…For example, Karl and Knauer (1984) reported on production inside sediment traps. But Silver et al (1984) reported that in the same sediment traps, microscopic examination showed that ciliated protozoa could sometimes account for 90% of the biomass. The lack of demonstrable adenine incorporation by ciliates thus calls into question the microbial production results for these sediment traps.…”

Section: Discussionmentioning

confidence: 99%

Does adenine incorporation into nucleic acids measure total microbial production?1

Fuhrman

Ducklow

Kirchman

et al. 1986

Limnology & Oceanography

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Incorporation of radioactive adenine into DNA has recently been used as a measure of total microbial production in marine environments, sometimes with unexpected results. We have examined two of the assumptions on which the method is based, particularly regarding the distribution of adenine uptake and nucleic acid content in mixed natural microbial assemblages. Size fractionation, autoradiography, and metabolic inhibition data indicate that the requirement that bacteria, algae, and protozoa have a uniform uptake and metabolism of added dissolved adenine dots not appear to hold. In systems where the biomass and productivity were greatly dominated by large phytoplankton, bacteria took up almost all of the adenine added at nanomolar concentrations. A separate experiment with marine ciliates also showed adenine uptake by eucaryotes to be negligible compared to that by bacteria, The method requires a measurement of microbial adenosine triphosphate (ATP) specific activity. In our experiments this quantity would be dominated by ATP in the eucaryotes that took up negligible adenine. In this situation, mostly eucaryotic biomass and not production would influence the "total microbial production" measurement. Second, the C: DNA ratio of 50 used in reports to date is too high for natural bacteria, which have a ratio closer to 5. We conclude that the method is likely to have produced large overestimates of production and that variations (e.g. with depth) may not reflect growth rates, but rather a complicated combination of activities and ratios of eucaryotic : procaryotic biomasses.

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“…Furthermore scuticociliates appear to be the most abundant ciliates in aggregates of suspended matter (Artolozaga et al 2000), and they have been associated with detritus (Silver et al 1984, Sherr et al 1986). Such clumps would undoubtedly be microns to millimetres in size, and thus the patches would be <<1 m. The samples of Pleuronema sp.…”

Section: Empirical Variograms (Points) and Fitted Models (Lines)mentioning

confidence: 99%

Spatial structure of planktonic ciliate patches in a tropical coastal lagoon: an application of geostatistical methods

Bulit

Díaz-Ávalos²,

Signoret

et al. 2003

Aquat. Microb. Ecol.

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The distribution of ciliates in a Mexican coastal lagoon was studied. The 4 goals were to: examine small-scale (<100 m) patches; indicate how geostatistical techniques can be used to examine these patches; make inferences concerning ciliate distribution and behaviour in the lagoon using geostatistical techniques; and assess geostatistics as a method for modelling ciliate distributions. Underlying these goals we attempt to make geostatistical techniques accessible to the non-expert. We provide an overview of the methodology, references to the geostatistical literature, and use our system as an example. Ciliates were sampled in a 40 × 40 m grid, divided at 10 m intervals; the grid was further divided into subsets, to determine 1 to 10 m scale variation. Between 30 and 35 points were sampled on 2 occasions (January and October). Ciliates were preserved with Lugol's iodine; abundance and species composition were determined by standard inverted microscopy. The work focused on 4 abundant ciliate species. We indicate, using the variographic analysis, that the abundance of 3 of the 4 ciliates is neither randomly nor homogeneously distributed, but exhibits a structured small-scale patchy distribution. We indicate that species-specific patterns of patchiness exist in stratified and in mixed waters, supporting the notion of behavioural niche-separation of planktonic ciliates. Patches of <13, <18, and < 77 m were formed by Lohmaniella oviformis, Tintinnopsis sp. and Strombidium sp., respectively. In contrast, Pleuronema sp. formed patches below the detection limits of the analysis (<1 m). Using geostatistical techniques, we established variograms and used them to model ciliate distribution and predict ciliate behaviour. Distribution maps were then generated that depicted the shape, distinctness, and gradient of the different patches. After analysing the data, we proposed a working definition of a 'ciliate patch': regions with abundance above the cut-off of the upper quartile from the kriging prediction model. Finally, error-maps were developed, indicating the coefficient of variation of the predicted distributions. We conclude that geostatistical analysis is a powerful tool to examine microzooplankton at small-scales, and we support its further application in the field.

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Ciliated protozoa associated with oceanic sinking detritus

Cited by 80 publications

References 12 publications

Bacterial growth in deep-sea sediment trap and boxcore samples

Bacterial growth in deep-sea sediment trap and boxcore samples

Does adenine incorporation into nucleic acids measure total microbial production?1

Spatial structure of planktonic ciliate patches in a tropical coastal lagoon: an application of geostatistical methods

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