Advantages to microbes of growth in permeable aggregates in marine systems1

Logan, Bruce E.; Hunt, James R.

doi:10.4319/lo.1987.32.5.1034

Cited by 126 publications

(111 citation statements)

References 64 publications

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“…Particle sinking rates clearly increase with depth as observed by Berelson (2002), most probably due to a loss of relatively light organic-rich materials (density around 1.06 g cm −3 ; Logan and Hunt, 1987) and increased scavenging of suspended fine-grained mineral particles, both of which would lead to higher particle densities. Our mean sinking rates were highest off NW Africa, decreasing southwards (Table 3).…”

Section: Discussionmentioning

confidence: 79%

Sinking rates and ballast composition of particles in the Atlantic Ocean: implications for the organic carbon fluxes to the deep ocean

2009

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Abstract. The flux of materials to the deep sea is dominated by larger, organic-rich particles with sinking rates varying between a few meters and several hundred meters per day. Mineral ballast may regulate the transfer of organic matter and other components by determining the sinking rates, e.g. via particle density. We calculated particle sinking rates from mass flux patterns and alkenone measurements applying the results of sediment trap experiments from the Atlantic Ocean. We have indication for higher particle sinking rates in carbonate-dominated production systems when considering both regional and seasonal data. During a summer coccolithophorid bloom in the Cape Blanc coastal upwelling off Mauritania, particle sinking rates reached almost 570 m per day, most probably due the fast sedimentation of densely packed zooplankton fecal pellets, which transport high amounts of organic carbon associated with coccoliths to the deep ocean despite rather low production. During the recurring winter-spring blooms off NW Africa and in opalrich production systems of the Southern Ocean, sinking rates of larger particles, most probably diatom aggregates, showed a tendency to lower values. However, there is no straightforward relationship between carbonate content and particle sinking rates. This could be due to the unknown composition of carbonate and/or the influence of particle size and shape on sinking rates. It also remains noticeable that the highest sinking rates occurred in dust-rich ocean regions off NW Africa, but this issue deserves further detailed field and laboratory investigations. We obtained increasing sinking rates with depth. By using a seven-compartment biogeochemical model, it was shown that the deep ocean organic carbon flux at a mesotrophic sediment trap site off Cape Blanc can be captured fairly well using seasonal variable particle sinking rates. Our model provides a total organic carbon flux of Correspondence to: G. Fischer (gerhard.fischer@uni-bremen.de) 0.29 Tg per year down to 3000 m off the NW African upwelling region between 5 and 35 • N. Simple parameterisations of remineralisation and sinking rates in such models, however, limit their capability in reproducing the flux variation in the water column.

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Section: Discussionmentioning

confidence: 79%

Sinking rates and ballast composition of particles in the Atlantic Ocean: implications for the organic carbon fluxes to the deep ocean

2009

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“…The larger the flocculated material the greater its porosity tends to be as well as it's potential to interact with the external environment producing a more efficient system. Uptake of nutrients by microorganisms has been found to be more efficient when flocculated than as a single cell (Logan and Hunt, 1987). It would not be surprising if these particles supported a diverse group of organisms.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Bioflocs in a No Water Exchange Super-intensive System for the Production of Food Size Pacific White Shrimp <i>Litopenaeus vannamei</i>

Haslun

Correia²,

Strychar³

et al. 2012

ija

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Zero exchange super-intensive recirculating aquaculture systems (RAS) represent an environmentally "friendly" alternative to traditional shrimp culture methods, however the susceptibility to pathogens typically increases as the density of cultured organisms increases. The study describes a greenhouse-enclosed super-intensive RAS, utilizing culture water from a 62-day nursery trial, to grow juvenile (0.99 g) Litopenaeus vannamei, Pacific White Shrimp, to market-size under high stocking density (450/m 3 ). The study evaluated the effects of foam fractionation and settling tank particulate control methods on water quality and microbial particulate related flora in four 40 m 3 tanks with two replicates per control method under no water exchange. Microbial communities were distinguished at the gram-stain level using flow cytometric fluorescent activated cell sorter (FACS) methods. Differentiation between all other populations of organisms and particles between 1~20 μm was based upon autofluorescence and forward scatter (a size indicative light parameter) using FACS. Analysis of variance indicated that the microbial communities associated with each particulate control method did not deviate from one another significantly (p>0.05). Gram-positive bacteria were the dominate fraction regardless of particulate control method (p<0.05). Six unique autofluorescence signals were consistently present within each RAS. This study is a first step in using flow cytometry as a tool to document changes in microbial communities in no water exchange super-intensive system for production of marketable shrimp. Shrimp yield and survival was high: 9.34~9.75 kg/m 3 and 94.5%~96.9%, respectively. Further, the data suggest that the use of pre-conditioned water may help to prevent ammonia and nitrite overload and decrease pathogenic organism prevalence.

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“…The apparent porosity of marine aggregates is high, greater than 0.9990 in > 5 mm diameter aggregates (Alldredge & Gotschalk 1988). Flow through porous aggregates has so far not been verified experimentally and the impact of any potential flow has only been quantified from model calculations, which suggest that flow within large (> 7 mm), porous and fast-sinking aggregates may increase mass transfer to attached cells within aggregates 1.0-to 2.1-fold compared to that to free-living cells (Logan & Hunt 1987, Logan & Alldredge 1989). The oxygen gradients around our < 6 mm large field-sampled marine aggregates, however, are well described by the model for impermeable aggregates to which mass transfer is potentially 4-to 20-fold enhanced during sedimentation.…”

Section: Scmentioning

confidence: 99%

Fluid motion and solute distribution around sinking aggregates. I. Small-scale fluxes and heterogeneity of nutrients in the pelagic environment

Kiørboe¹,

Ploug²,

Thygesen³

2001

Mar. Ecol. Prog. Ser.

130

176

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Marine snow aggregates are sites of elevated biological activity. This activity depends on the exchange of solutes (O 2 , CO 2 , mineral nutrients, dissolved organic material, etc.) between the aggregate and the environment and causes heterogeneity in the distribution of dissolved substances in the ambient water. We described the fluid flow and solute distribution around a sinking aggregate by solving the Navier-Stokes' equations and the advection-diffusion equations numerically. The model is valid for Reynolds numbers characteristic of marine snow, up to Re = 20. The model demonstrates the importance of a correct flow environment when making biological rate-measurements on aggregates (e.g., oxygen consumption/production, growth rates of bacteria and phytoplankton) because both solute fluxes and internal solute concentrations depend strongly on the flow environment. Observations of flow and oxygen-concentration fields in the vicinity of both artificial and natural oxygen-consuming aggregates that are suspended in a flow compare well with model predictions, thus suggesting that our set-up is suitable for making biological rate measurements. The sinking aggregate leaves a long slender plume in its wake, where solute concentration is either elevated (leaking substances) or depressed (consumed substances) relative to ambient concentration. Such plumes may impact the nutrition of osmotrophs. For example, based on published solubilization rates of aggregates we describe the amino acid plume behind a sinking aggregate (0.1 to 1.0 cm radius). The volume of the plume with amino acid concentrations high enough to significantly affect bacterial uptake rates is ca 100 × the volume of the aggregate itself. Thus, sinking aggregates may create significant microniches also for free-living bacteria.

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Advantages to microbes of growth in permeable aggregates in marine systems1

Cited by 126 publications

References 64 publications

Sinking rates and ballast composition of particles in the Atlantic Ocean: implications for the organic carbon fluxes to the deep ocean

Sinking rates and ballast composition of particles in the Atlantic Ocean: implications for the organic carbon fluxes to the deep ocean

Characterization of Bioflocs in a No Water Exchange Super-intensive System for the Production of Food Size Pacific White Shrimp <i>Litopenaeus vannamei</i>

Fluid motion and solute distribution around sinking aggregates. I. Small-scale fluxes and heterogeneity of nutrients in the pelagic environment

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