Vertical Flux of Biogenic Carbon in the Ocean: Is There Food Web Control?

Rivkin, Richard B.; Legendre, Louis; Deibel, Don; Tremblay, Jean‐Éric; Klein, Bert; Crocker, Kenneth M.; Roy, Suzanne; Silverberg, Norman; Lovejoy, Connie; Mesplé, Fabrice; Romero, N.; Anderson, M. Robin; Matthews, P. C.; Savenkoff, Claude; Vézina, Alain F.; Therriault, Jean‐Claude; Wesson, J. C.; Bérubé, C; Ingram, R. Grant

doi:10.1126/science.272.5265.1163

Cited by 112 publications

(60 citation statements)

References 35 publications

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“…With data from the GSL only, Rivkin et al [1996] concluded that unlike other systems, the gulf exports approximately the same amount of carbon to the bottom whether the surface waters are undergoing bloom or nonbloom conditions. Since the composition of the export is changing from more chlorophyllous material in bloom conditions compared to more fecal pellets in nonbloom conditions, it may well be that the LSLE is a source of biogenic carbon for the GSL throughout the summer.…”

Section: Resultsmentioning

confidence: 99%

Turbulent nitrate fluxes in the Lower St. Lawrence Estuary, Canada

et al. 2015

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Turbulent vertical nitrate fluxes were calculated using new turbulent microstructure observations in the Lower St. Lawrence Estuary (LSLE), Canada. Two stations were compared: the head of the Laurentian Channel (HLC), where intense mixing occurs on the shallow sill that marks the upstream limit of the LSLE, and another station located about 100 km downstream (St. 23), more representative of the LSLE mean mixing conditions. Mean turbulent diffusivities and nitrate fluxes at the base of the surface layer for both stations were, respectively (with 95% confidence intervals): K HLC Observations suggest that the interplay between large isopleth heaving near the sill and strong turbulence is the key mechanism to sustain such high turbulent nitrate fluxes at the HLC (two to three orders of magnitude higher than those at Station 23). Calculations also suggest that nitrate fluxes at the HLC alone can sustain primary production rates of 3:4ð0:6; 11Þ g C m 22 mo 21 over the whole LSLE, approximately enough to account for a large part of the phytoplankton bloom and for most of the postbloom production. Surfacing nitrates are also believed to be consumed within the LSLE, not leaving much to be exported to the rest of the Gulf of St. Lawrence.

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Section: Resultsmentioning

confidence: 99%

Turbulent nitrate fluxes in the Lower St. Lawrence Estuary, Canada

et al. 2015

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“…A number of possible explanations for the observed correlations were evaluated as follows: There is obviously no close coupling of BSi and OM in the particle flux to the seafloor and within the sediment which could explain the correlation of Si:O 2 fluxes. Although both BSi and OM are major components of diatoms that are found in certain ratios in the living organisms (Ragueneau et al, 2000, the biogeochemical cycles of silicon and carbon decouple both vertically and horizontally in the water column (Rivkin et al, 1996;Gallinari et al, 2002;Ragueneau et al, 2002). Considering the multitude of water depths, and the different regions investigated, related concentrations in the particle rain reaching the seafloor are highly unlikely.…”

Section: Discussionmentioning

confidence: 99%

Microbial mediation of benthic biogenic silica dissolution

Holstein

Hensen

2009

Geo-Mar Lett

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Pore water profiles from 24 stations in the South Atlantic (located in the Guinea, Angola, Cape, Guyana, and Argentine basins) show good correlations of oxygen and silicon, suggesting microbially mediated dissolution of biogenic silica. We used simple analytical transport and reaction models to show the tight coupling of the reconstructed process kinetics of aerobic respiration and silicon regeneration. A generic transport and reaction model successfully reproduced the majority of Si pore water profiles from aerobic respiration rates, confirming that the dissolution of biogenic silica (BSi) occurs proportionally to O 2 consumption. Possibly limited to well-oxygenated sediments poor in BSi, benthic Si fluxes can be inferred from O 2 uptake with satisfactory accuracy. Compared to aerobic respiration kinetics, the solubility of BSi emerged as a less influential parameter for silicon regeneration. Understanding the role of bacteria for silicon regeneration requires further investigations, some of which are outlined. The proposed aerobic respiration control of benthic silicon cycling is suitable for benthic-pelagic models. The empirical relation of BSi dissolution to aerobic respiration can be used for regionalization assessments and estimates of the silicon budget to increase the understanding of global primary and export production patterns.

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“…Past attempts to determine carbon flux simplistically as a function of primary production have consistently met with failure. So, it is now acknowledged that food web structure plays an fundamental role in regulating carbon flux (Rivkin et al, 1996). The discovery of TEP and their role in the aggregation of particles has now further improved our understanding of the biogeochemical cycling of carbon.…”

Section: Changing Conceptsmentioning

confidence: 99%

“…Which fraction of primary produced particles sinks to depth, also depends on the type of food web present (Rivkin, Legendre, Deibel, Tremblay, Klein, Crocker et al, 1996). Particles may be utilized by bacteria or grazed by eukaryotes.…”

Section: Food-web Structurementioning

confidence: 99%

Transparent exopolymer particles (TEP) in aquatic environments

Passow

2002

Progress in Oceanography

958

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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Vertical Flux of Biogenic Carbon in the Ocean: Is There Food Web Control?

Cited by 112 publications

References 35 publications

Turbulent nitrate fluxes in the Lower St. Lawrence Estuary, Canada

Turbulent nitrate fluxes in the Lower St. Lawrence Estuary, Canada

Microbial mediation of benthic biogenic silica dissolution

Transparent exopolymer particles (TEP) in aquatic environments

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