Structural and chemical analysis of marine aggragates: in situ macrophotography and laser confocal and electron microscopy

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

doi:10.1007/bf00347441

Cited by 26 publications

(18 citation statements)

References 46 publications

(49 reference statements)

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“…Attempts to determine the life-history or successional patterns of marine snow have been hindered by logistical and technical limitations. SCLM techniques may help to determine subcomponent arrangements, porosities, and relative densities of marine snow that are related to the particle's structure and composition (Cowen and Holloway 1996). These properties, in turn, are important in evaluating the dynamics involved in particle aggregation and in the ultimate role marine snow plays in the distribution and flux of suspended particles in the ocean.…”

Section: Resultsmentioning

confidence: 99%

“…SOEST contribution number 455 1. concentrate a number of dissolved and colloidal compounds in seawater such as amino acids and proteins (Dugan et al 1970;Joyce and Dugan 1970), as well as a number of metals (Corpe 1975;Brown and Lester 1982;Cowen and Silver 1984). Metals have been found closely associated with bacterial exopolymers in the sediments (Nealson 1983) and in the water column (Cowen and Silver 1984;Cowen and Bruland 1985;Cowen and Li 1991). Relative protein abundance has been used as a proxy for the degree of decomposition of organic material collected by sediment traps (Hecky et al 1973;Haake et al 1993).…”

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confidence: 99%

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

Holloway

Cowen

1997

Limnology & Oceanography

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A technique was developed to image marine snow particles by scanning confocal laser microscopy (SCLM). This method allows structural and compositional characterization of fully hydrated marine snow particles with minimal disruption of the particle structure. High specificity fluorescent stains permitted sequential imaging of selected polysaccharides (concanavalin A: specific for mannose and glucose polymer:;), proteins [5-(4,6-dichlorotriazin-2-yl) aminofluorescein], and DNA (propidium iodide). Chl a autofluorescence can rtlso be imaged. SCLM produced optical slices of marine snow particles that were suited for a number of image-processing applications. These applications include high-resolution fluorescently derived optical slices and composite images produced from combined optical slices. Initial observations suggest that marine snow particles found in the oligotrophic Pacific Ocean vary in composition and structure. Variations in polysaccharide and protein composition of marine snow particles may be related to particle morphology. When combined with other conventional analysis, such as epifluorescent and electron microscopy, LSCM can provide important contributions to characterizing composition and structure of marine snow.

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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

Holloway

Cowen

1997

Limnology & Oceanography

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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: 92%

Transparent exopolymer particles (TEP) in aquatic environments

Passow

2002

Progress in Oceanography

955

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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“…213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 These data provide a clear picture of Rhizosolenia mat abundance across the Pacific Ocean as well as within their vertical migration range. The latitudinal distribution extends from ~24° to ~35° N with additional observations near Oahu, Hawai'i (Cowen & Holloway 1996), the coastal California current, and equatorial Pacific (Alldredge & Silver 1982). Mats were observed over 50° of longitude (~1/2 the width of the Pacific Ocean) and were abundant at the western terminus of the cruise set.…”

Section: Nitrogen Isotope Valuesmentioning

confidence: 69%

Upward nitrate transport by phytoplankton in oceanic waters: balancing nutrient budgets in oligotrophic seas

Villareal

Pilskaln

Montoya

et al. 2014

Preprint

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In oceanic gyres, primary producers are numerically dominated by small (1-5 µm diameter) pro-and eukaryotic cells that primarily utilize recycled nutrients produced by rapid grazing turnover in a highly efficient microbial loop. Continuous losses of nitrogen to depth by sinking, either as single cells, aggregates or fecal pellets, are balanced by both nitrate inputs at the base of the euphotic zone and nitrogen-fixation. This input of N (new nitrogen) to balance export losses (the biological pump) is a fundamental aspect of nitrogen cycling and central to understanding carbon fluxes in the ocean. In the Pacific Ocean, detailed nitrogen budgets at the time-series station HOT require upward transport of nitrate from the nutricline (80-100 m) into the surface layer (~0-40 m) to balance productivity and export needs. However, concentration gradients are negligible and cannot support the fluxes. Physical processes can inject nitrate into the base of the euphotic zone, but the mechanisms for transporting this nitrate into the surface layer across many 10s of m in highly stratified systems are unknown.In these seas, vertical migration by the very largest 10 2 -10 3 µm diameter) phytoplankton is common as a survival strategy to obtain nitrogen from sub-euphotic zone depths. This vertical migration is driven by buoyancy changes rather than by flagellated movement and can provide upward nitrogen transport as nitrate (mM concentrations) in the cells. However, the contribution of vertical migration to nitrate transport has been difficult to quantify over the required basin scales. In this study, we use towed optical systems and isotopic tracers to PrePrintsIntroduction Nitrogen in the euphotic zone of the open sea has long been recognized to partition into two distinct pools of availability (Dugdale & Goering 1967). New nitrogen represents introduction of N from outside the euphotic zone, either in the form of deep NO 3 -or nitrogenfixation, while regenerated N results from consumption and remineralization of dissolved or particulate N (Dugdale & Goering 1967). While regenerated N dominates the total phytoplankton uptake, new N is critical to balance losses due to vertical fluxes and is linked to total system productivity (Eppley & Peterson 1979). This has been expressed as the f ratio where 'f' = new/total N uptake and ranges from 0-1. On longer time scales, new N input must balance sedimentary losses or the system will experience net losses of nitrogen (Eppley & Peterson 1979). The surface waters of the open ocean are considered low 'f' ratio environments: N and P often occur at nM concentrations, and ammonium is the dominant form taken up by phytoplankton (Lipschultz et al. 1996;Raimbault et al. 2008;Wu et al. 2000). The f ratio increases in the light-limited lower depths of the euphotic zone due to the increased availability of nitrate at the nutricline, thus creating what has been recognized as a two-layered structure (Goldman 1988). This general pattern can be modified in regions of low iron input, where iron ava...

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Structural and chemical analysis of marine aggragates: in situ macrophotography and laser confocal and electron microscopy

Cited by 26 publications

References 46 publications

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

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

Transparent exopolymer particles (TEP) in aquatic environments

Upward nitrate transport by phytoplankton in oceanic waters: balancing nutrient budgets in oligotrophic seas

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