Development of a scanning confocal laser microscopic technique to examine the structure and composition of marine snow

Holloway, C. F.; Cowen, James P.

doi:10.4319/lo.1997.42.6.1340

Cited by 37 publications

(26 citation statements)

References 14 publications

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“…Thirdly, one may find in the literature the first attempts to use CLSM to study aquatic aggregates , 1997, Holloway & Cowan 1997. The FITC-stained aggregates showed the cell distribution within the floc.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, the topic 'suspended particulate matter' (SPM) has been the subject of several comprehensive books (Eisma 1993, Rao 1993, Wotton 1994b, Kausch & Michaelis 1996. Aggregates in aquatic systems have been studied in oceans and estuaries (Albright et al 1986, Simon et al 1990, Smith et al 1992, Delong et al 1993, Lampitt et al 1993, Stehr et al 1995, Zimmermann & Kausch 1996, Capone et al 1997, Holloway & Cowan 1997, Hyun et al 1997, Zimmermann 1997, in lakes (Simon 1987, Grossart & Simon 1993, Weiss et al 1996, Grossart et al 1997 and in rivers (Droppo & Ongley 1994, Hoch et al 1995, Berger et al 1996. Due to their appearance the terms 'marine snow' and 'lake snow' were introduced.…”

Section: Introductionmentioning

confidence: 99%

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In situ cell and glycoconjugate distribution in river snow studied by confocal laser scanning microscopy

Neu¹

2000

Aquat. Microb. Ecol.

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Aggregates from the river Elbe (Germany) were collected and examined by confocal laser scanning microscopy. The river snow was directly transferred into coverslip chambers and observed without any embedding and fixation procedure. River snow samples were examined in the reflection and fluorescence mode to record mineral content and autofluorescence signals. Spatial distribution of microb~al cells within the aggregates was shown with general nucleic acid specific stains (SYTO 9, SYTO 64). The polymeric matnx of the river snow was demonstrated by using a panel of fluorescently labelled lectins. Staining with FITC and TRITC labelled lectins and simultaneous dual channel unaging showed the distribution of different types of glycoconjugates. The binding pattern observed included bacterial cell surface labelling and cloud-type labelling of extracellular polymeric substances (EPS). In addition, dual staining combined with triple-channel recording was employed to clearly separate the signal in the red channel originating from TRITC-lectin or SYTO 64 nucleic acid stain from the far red autofluorescence originating from chlorophyll-containing organisms. With this approach the fully hydrated, living, 3-dimensional architecture of aquatic aggregates was investigated. Application of lectins demonstrated the heterogeneity of the EPS matrix in between the cellular constituents of the river snow community. The chemical heterogeneity of river snow may be significant for sorption and transport of nutrients and contaminants in lotlc aquatic environments. This in situ technique may be also useful to examine interfacial microbial consortia in other habitats. Finally, it is suggested to employ in situ lectin staining to probe for the glycoconjugate distribution at the polymer level similar to in situ hybridisation with rRNA targeted oligonucleotides at the cellular level.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

In situ cell and glycoconjugate distribution in river snow studied by confocal laser scanning microscopy

Neu¹

2000

Aquat. Microb. Ecol.

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“…A polysaccharide matrix has been found to surround and connect composite particles in all marine and lake aggregates investigated (Rieman, 1989;Alldredge, Passow & Logan, 1993;Cowen & Holloway, 1996;Grossart, 1996;Holloway & Cowen, 1997;Alldredge, Passow & Haddock, 1998). Most of this material stains with alcian blue suggesting that the mucus matrix consists predominantly of TEP.…”

Section: Contribution Of Tep To Aggregatesmentioning

confidence: 99%

Transparent exopolymer particles (TEP) in aquatic environments

Passow

2002

Progress in Oceanography

947

951

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Since the development of methods to quantify transparent exopolymer particles (TEP) 1993, it has been shown that these gel-particles are not only ubiquitous and abundant, but also play a significant role in the biogeochemical cycling of elements and the structuring of food webs. TEP may be quantified either microscopically or colorimetrically. Although data based on measurements using one or other of these methods are not directly comparable, the results are consistent. TEP abundances in fresh and marine waters are in the same range as those of phytoplankton, with peak values occurring during phytoplankton blooms. TEP are very sticky particles that exhibit the characteristics of gels, and consist predominantly of acidic polysaccharides. In marine systems the majority of TEP are formed abiotically from dissolved precursors, which are released by phytoplankton that are either actively growing or are senescent. TEP are also generated during the sloughing of cell surface mucus and the disintegration of colonial matrices. The impact of exopolymers in the creation of microhabitats and in the cycling of trace compounds varies with the state in which the polymers occur, either as particles or as solute slimes. As particles, TEP provide surfaces for the colonization by bacteria and transfer by adsorption, trace solute substances into the particulate pool. As dissolved polymers they are mixed with the water and can neither be filtered nor aggregated. Because of their high abundances, large size and high stickiness, TEP enhance or even facilitate the aggregation of solid, non-sticky particles. They have been found to form the matrices of all marine aggregates investigated to date. By aggregating solid particles, TEP promote the sedimentation of particles, and, because their carbon content is high, their direct contribution to fluxes of carbon into deep water is significant. The direct sedimentation of TEP may represent a mechanism for the selective sequestration of carbon in deep water, because the C:N ratios of TEP lie well above the Redfield ratio. The turnover time of TEP as a result of bacterial degradation appears to range from hours to months, depending on the chemical composition and age of TEP. TEP may also be utilized not only by filter feeders (some protozoans and appendicularian) but TEP-rich microaggregates, consisting of pico-and nano-plankton are also readily grazed by euphausiids, thus permitting the uptake of particles that would otherwise be too small to be grazed directly by euphausiids. This short-circuits food chains and links the microbial food-web to the classical food-web. It is suggested that this expansion of the concept of food webs, linking the microbial loop with an aggregation web will provide a more complete description of particle dynamics. 

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“…Upper ocean tracers such as 234 Th are fully quantitative, but yield no particle-specific data since measurements are integrated over the entire mixed layer (Buesseler et al 1995). SCUBA collection has been very effective in sampling aggregates while maintaining particle structure (Trent et al 1978), and especially when paired with confocal microscopy (Holloway and Cowen 1997), yields excellent high resolution images of particle substructure. However, this sampling is of necessity limited to larger particles and limited to depths accessible by diving.…”

Section: Acknowledgmentsmentioning

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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Development of a scanning confocal laser microscopic technique to examine the structure and composition of marine snow

Cited by 37 publications

References 14 publications

In situ cell and glycoconjugate distribution in river snow studied by confocal laser scanning microscopy

In situ cell and glycoconjugate distribution in river snow studied by confocal laser scanning microscopy

Transparent exopolymer particles (TEP) in aquatic environments

Mass sedimentation of picoplankton embedded in organic aggregates

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