The formation of large marine snow and its sustained residence in surface waters

Riebesell, Ulf

doi:10.4319/lo.1992.37.1.0063

Cited by 87 publications

(42 citation statements)

References 20 publications

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“…The redistribution of particulate organic matter in the open ocean is not solely based on the 'sinking leg' but also on the 'rising leg', i.e. upward fluxes of organic particles due to water movements or inclusions of gas bubbles (Yayanos 1986, Riebesell 1992. In addition, bacteria may be transported through different water layers when attached to zooplankton (Grossart et al 2009).…”

Section: Discussionmentioning

confidence: 99%

Hydrostatic pressure affects physiology and community structure of marine bacteria during settling to 4000 m: an experimental approach

Grossart¹,

Gust²

2009

Mar. Ecol. Prog. Ser.

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Section: Discussionmentioning

confidence: 99%

Hydrostatic pressure affects physiology and community structure of marine bacteria during settling to 4000 m: an experimental approach

Grossart¹,

Gust²

2009

Mar. Ecol. Prog. Ser.

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“…TEP are very sticky and possible trapping of bubbles, generated during experiments, can also cause TEP to ascend. Bubbles can be generated by photosynthesis and trapped in aggregates (Riebesell 1992); however, in our experiments, filtered seawater was used to produce TEP. Therefore, it is not likely that any bubbles were generated by organisms during TEP formation.…”

Section: Resultsmentioning

confidence: 99%

“…the water (Alldredge and Crocker 1995;MacIntyre et al 1995) and turbulence (Shanks 2002). The density of aggregates is a function of the presence of gas enclosures (Riebesell 1992), the density of the enclosed solid matter (Asper 1987;Azetsu-Scott and Johnson 1992), and the TEP to cell ratio (Engel and Schartau 1999). The present study evaluates in detail the effect of TEP on the density and sinking velocity of aggregates.…”

Section: Acknowledgmentsmentioning

confidence: 99%

Ascending marine particles: Significance of transparent exopolymer particles (TEP) in the upper ocean

Azetsu-Scott¹,

Passow²

2004

Limnology & Oceanography

224

146

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The high abundance of transparent exopolymer particles (TEP) in marine and freshwater greatly affects particle dynamics. TEP act as glue for colliding particles and form the matrix in aggregates, thereby altering aggregation dynamics. We studied the sinking behavior of freshly produced, particle-free TEP and of aggregates composed of TEP and latex spheres in a laboratory using water collected from Santa Barbara Channel, California. Particle-free TEP ascend and accumulate in the surface layer of a settling column at an average velocity of 1.6 ϫ 10 Ϫ4 cm s Ϫ1 . The estimated density of TEP ranges from 0.70 to 0.84 g cm Ϫ3 . TEP also transported latex spheres of 45.6 and 1.82 m in diameter and a density of 1.05 g cm Ϫ3 to the surface layer. We describe a simple model illustrating the role of TEP for the vertical transport of solid particles. The densities and relative proportions of TEP, solid particles, and interstitial water within an aggregate determine its sinking or ascending velocity. High ratios of TEP to solid particles retard the sinking of aggregates, prolonging their residence time in the surface ocean. Our results demonstrate that TEP can provide a vehicle for the upward flux of biological and chemical components in the marine environment, including bacteria, phytoplankton, carbon, and reactive trace elements.

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“…In fact, there is good evidence that the initial accumulation of mucilage at the density discontinuity layer in the northern Adriatic Sea is a result of this phenomenon (Alldredge 1999, Degobbis et al 1999 Aggregates dominated by cyanobacteria-derived material exhibit very low sinking rates or do not sink at all due to the very low excess density (Grossart et al 1997). Macroaggregates with intensive primary production and entrapped oxygen gas bubbles may even move upward in the water column (Riebesell 1992, Herndl 1992). This may also occur when filamentous and gas vacuole-containing cyanobacteria are abundant (Capone et al 1997, Stal et al 1999).…”

Section: Macroscopic Aggregatesmentioning

confidence: 99%

Microbial ecology of organic aggregates in aquatic ecosystems

Simon¹,

Grossart²,

Schweitzer³

et al. 2002

Aquat. Microb. Ecol.

927

858

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Macroscopic organic aggregates, which are > 500 µm and known as marine and lake snow, are important components in the turnover, decomposition and sinking flux of both organic and inorganic matter and elements in aquatic ecosystems. They are composed of various organic and inorganic materials depending largely on the given system and environmental conditions. The systems include the pelagic limnetic, the neritic and oceanic marine region, as well as shallow turbid environments, e.g. rivers, the littoral zone of lakes, estuaries and tidally affected coastal areas with intense turbulence and a high load of suspended matter. Aggregate abundance and size vary greatly among these systems. Macroaggregates are heavily colonized by bacteria and other heterotrophic microbes and greatly enriched in organic and inorganic nutrients as compared to the surrounding water. During the last 15 yr, many studies have been carried out to examine various aspects of the formation of aggregates, their microbial colonization and decomposition, nutrient recycling and their significance for the sinking flux. They have been identified as hot-spots of the microbial decomposition of organic matter. Further, microaggregates, which are < 5 to 500 µm in size and stained by different dyes, such as transparent exopolymer particles (TEP) and Coomassie blue-stained particles, have been discovered and shown also to be important in the formation and decomposition of macroaggregates. In this review we give an overview of the present state of the microbial ecology of macro-and microaggregates, including the mentioned points but highlighting in particular the recent findings on the bacterial colonization of aggregates using molecular tools, their microbial decomposition and mineralization, and the significance of protozoans and metazoans for the colonization and decomposition of macroaggregates. Today it is evident that not only the aggregates but also their surroundings are sites and hot-spots of microbial processes, with the plume of solutes leaking out of the aggregates and greatly extending the volume of the intense decomposition processes. This microheterogeneity has important implications for the spatial and temporal dynamics of the organic-matter field in aquatic ecosystems and for our understanding of how heterotrophic organisms are involved in the decomposition of organic matter. The significance of aggregate-associated microbial processes as key processes and also for the overall decomposition and flux of organic mattervaries greatly among the various systems, and is greatly affected by the total amount of suspended particulate matter. A conclusion from the presented studies and results is that the significance of bacteria for the formation and decomposition of aggregates appears to be much greater than previously estimated. For a better understanding of the functioning of aquatic ecosystems it is of great importance to include aggregate-associated processes in ecosystem modeling approaches.

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The formation of large marine snow and its sustained residence in surface waters

Cited by 87 publications

References 20 publications

Hydrostatic pressure affects physiology and community structure of marine bacteria during settling to 4000 m: an experimental approach

Hydrostatic pressure affects physiology and community structure of marine bacteria during settling to 4000 m: an experimental approach

Ascending marine particles: Significance of transparent exopolymer particles (TEP) in the upper ocean

Microbial ecology of organic aggregates in aquatic ecosystems

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