Influence of transparent exopolymer particles (TEP) on sinking velocity of Nitzschia closterium aggregates

Engel, Anja; Schartau, Markus

doi:10.3354/meps182069

Cited by 94 publications

(97 citation statements)

References 26 publications

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“…TEPs occupy a significant fraction of aggregate volume but contribute little to DW in diatom aggregates (Ploug and Passow, 2007). TEP densities can be lower than that of seawater and decrease aggregate sinking velocities (Engel and Schartau, 1999;Azetsu-Scott and Passow, 2004). The porosity of E. huxleyi aggregates has been shown to be ∼96% and that of S. costatum aggregates to be ∼99% (Ploug et al 2008a).…”

Section: Discussionmentioning

confidence: 99%

Ballast minerals and the sinking carbon flux in the ocean: carbon-specific respiration rates and sinking velocity of marine snow aggregates

2010

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Abstract.Recent observations have shown that fluxes of ballast minerals (calcium carbonate, opal, and lithogenic material) and organic carbon fluxes are closely correlated in the bathypelagic zones of the ocean. Hence it has been hypothesized that incorporation of biogenic minerals within marine aggregates could either protect the organic matter from decomposition and/or increase the sinking velocity via ballasting of the aggregates. Here we present the first combined data on size, sinking velocity, carbon-specific respiration rate, and composition measured directly in three aggregate types; Emiliania huxleyi aggregates (carbonate ballasted), Skeletonema costatum aggregates (opal ballasted), and aggregates made from a mix of both E. huxleyi and S. costatum (carbonate and opal ballasted). Overall average carbon-specific respiration rate was ∼0.13 d −1 and did not vary with aggregate type and size. Ballasting from carbonate resulted in 2-to 2.5-fold higher sinking velocities than those of aggregates ballasted by opal. We compiled literature data on carbon-specific respiration rate and sinking velocity measured in aggregates of different composition and sources. Compiled carbon-specific respiration rates (including this study) vary between 0.08 d −1 and 0.20 d −1 . Sinking velocity increases with increasing aggregate size within homogeneous sources of aggregates. When compared across different particle and aggregate sources, however, sinking velocity appeared to be independent of particle or aggregate

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Section: Discussionmentioning

confidence: 99%

Ballast minerals and the sinking carbon flux in the ocean: carbon-specific respiration rates and sinking velocity of marine snow aggregates

2010

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“…The relative proportion of TEP compared to solid particles determines sinking speed of aggregates. Aggregates formed by Nitzschia closterium, which contained a relatively higher proportion of TEP showed lower sinking velocities, than TEP-poor aggregates of the same size and type (Engel & Schartau, 1999).…”

Section: Contribution Of Tep To Aggregatesmentioning

confidence: 99%

Transparent exopolymer particles (TEP) in aquatic environments

Passow

2002

Progress in Oceanography

948

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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“…When the amount of nitrate available for NP SV production decreases, as the transect approaches the southern oligotrophic stations, it is obvious that the need for additional particulate material like TEP to promote aggregate formation will become higher. Because TEP do not sink by themselves and slow down the settling velocity of aggregates (Engel and Schartau, 1999), the formation of aggregates that are 'heavy' enough to sink will have a minimum requirement for solid particles. This may not be fulfilled in oligotrophic regions.…”

Section: Article In Pressmentioning

confidence: 99%

Distribution of transparent exopolymer particles (TEP) in the northeast Atlantic Ocean and their potential significance for aggregation processes

Engel

2004

Deep Sea Research Part I: Oceanographic Research Papers

129

104

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The abundance of transparent exopolymer particles (TEP) was determined in the northeast Atlantic Ocean (40-55 N, B20 W) during several cruises from June to November 1996. An accumulation of TEP in the water column was observed at bloom and post-bloom sites along a 20 W transect in June/July (maximum concentration: 124 mg Gum Xanthan equivalents (Xeq.) l À1 ), but concentrations were uniformly low (mean concentration: 28.5710.2 mg Xeq. l À1 ) during autumn at the BIOTRANS site (47 N, 20 W). TEP concentrations in the open northeast Atlantic were considerably lower than previously published values from coastal sites. However, during June/July TEP:Chl a (weight/ weight) ratios were comparable to values at coastal seas. It is suggested that phytoplankton production modulates TEP concentration in the open ocean as it does in coastal systems. TEP contributed significantly to the organic carbon pool as derived from the ratio TEP-C:POC, in summer (mean percentage: 1777.5; w/w), as well as in autumn (mean percentage: 18711, w/w). The potential influence of TEP on particle coagulation rates in the northeast Atlantic was assessed from estimates of their influence on particle stickiness and on particle volume concentrations. This indicated that TEP may be essential for initiating particle aggregation at low biomass concentrations, typical for open ocean sites. r

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Influence of transparent exopolymer particles (TEP) on sinking velocity of Nitzschia closterium aggregates

Cited by 94 publications

References 26 publications

Ballast minerals and the sinking carbon flux in the ocean: carbon-specific respiration rates and sinking velocity of marine snow aggregates

Ballast minerals and the sinking carbon flux in the ocean: carbon-specific respiration rates and sinking velocity of marine snow aggregates

Transparent exopolymer particles (TEP) in aquatic environments

Distribution of transparent exopolymer particles (TEP) in the northeast Atlantic Ocean and their potential significance for aggregation processes

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