Oceanographic implications of non-newtonian properties found in phytoplankton cultures

Jenkinson, Ian R.

doi:10.1038/323435a0

Cited by 80 publications

(67 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This implies that inhibition may be at least partly mechanically mediated. It has been demonstrated that during phytoplankton blooms the thickening behaviour of algal polysaccharides may change rheological properties (Jenkinson 1986), and the study of bacterial extracellular polysaccharides indicated high apparent viscosity increasing markedly with bacterial concentration (Anton et al 1988). Jenkinson (1989) suggested that increased viscosity may even kill fish in some plankton blooms due to the high energy requirement for pumping the more viscous liquid.…”

Section: Discussionmentioning

confidence: 99%

Inhibition of copepod grazing by diatom exudates: a factor in the development of mucus aggregates?

Malej¹,

Harris²

1993

Mar. Ecol. Prog. Ser.

103

View full text Add to dashboard Cite

Dissolved polymers, especially polysaccharides, are thought to play an important role in formation of larger organic aggregates in the sea. Phytoplankton may exude considerable quantities of polymers, although the particular conditions conducive to release of these substances are not known. Such processes are implicated in the formation of large-scale gelatinous mucus aggregations in the Adriatic Sea. We investigated extracellular carbohydrate release in the diatoms Coscinodiscus granii, Stephanopyxis palmenana, Skeletonema costatum, Nitzschia delicatissima, Thalassiosira weissflogii, and 2 species of Chaetoceros, under different culture conditions, and examined whether these exudates interfered with copepod grazing. The copepod species studied are typical of Adriatic coastal enviroments. Our results indicate that during the exponential growth phase the contribution of the high-molecular-weight carbohydrate (HMWCHO) fraction to extracellular release was minor, except in phosphorus Limited medium. A shift towards an increased significance of HMWCHO was observed in the stationary phase for all species tested. Grazing experiments with Temora longicornis and Pseudocalanus elongatus demonstrated that copepod feeding was inhibited by HMWCHO diatom exudate and also stationary phase culture filtrate. Feeding rates were also adversely affected by the presence of pure HMW dextran used as a model substance. Copepod feeding was more strongly inhibited by &atom HMWCHO exudates than an equivalent concentration of pure dextran, suggesting an additional response to the chemical stimuli of algal exudates.

show abstract

Section: Discussionmentioning

confidence: 99%

Inhibition of copepod grazing by diatom exudates: a factor in the development of mucus aggregates?

Malej¹,

Harris²

1993

Mar. Ecol. Prog. Ser.

103

View full text Add to dashboard Cite

show abstract

“…cells (mm 3 ). Because encased volume of TEP is estimated, the volume calculations overestimate TEP (Kiørboe & Hansen, 1993 of free fibrillar polymers changes the rheological properties and viscosity of seawater (Jenkinson, 1986) altering the flow fields experienced by cells and increasing the persistence of microzones and chemical patchiness (Jenkinson & Wyatt, 1992;Jenkinson, 1993). As TEP, the same polymers are responsible for the formation of relatively stable microhabitats in aggregates.…”

Section: Microenvironments Of Microbesmentioning

confidence: 99%

Transparent exopolymer particles (TEP) in aquatic environments

Passow

2002

Progress in Oceanography

958

951

View full text Add to dashboard Cite

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. 

show abstract

“…It is likely that in many instances the ocean is far from a newtonian fluid (Jenkinson 1986). It has been suggested that at the microscale, seawater is an organic matter continuum of tangled polymers and embedded particles (Azam 1998), including transparent exoploymeric particles (TEP) (Alldredge et al 1993), proteinaceous coomassie stained particles (CSP) (Long & Azam 1996), and organic sub-micrometer particles (Koike et al 1990).…”

Section: Turbulencementioning

confidence: 99%

“…It has been suggested that at the microscale, seawater is an organic matter continuum of tangled polymers and embedded particles (Azam 1998), including transparent exoploymeric particles (TEP) (Alldredge et al 1993), proteinaceous coomassie stained particles (CSP) (Long & Azam 1996), and organic sub-micrometer particles (Koike et al 1990). The potentially gel-like nature of this organic matter continuum (Azam 1998, Chin et al 1998, and the bulk effects of phytoplankton exuded polysaccharides, may act to increase water viscosity and influence turbulent drag by elastic effects (Jenkinson 1986, Jenkinson & Biddanda 1995. Lack of rheometrical data taking into account the non-newtonian properties of seawater could impair the accurate modelling of smallscale oceanographic processes (Jenkinson 1986).…”

Section: Turbulencementioning

confidence: 99%

“…The potentially gel-like nature of this organic matter continuum (Azam 1998, Chin et al 1998, and the bulk effects of phytoplankton exuded polysaccharides, may act to increase water viscosity and influence turbulent drag by elastic effects (Jenkinson 1986, Jenkinson & Biddanda 1995. Lack of rheometrical data taking into account the non-newtonian properties of seawater could impair the accurate modelling of smallscale oceanographic processes (Jenkinson 1986). The rheological properties of the organic matter continuum are likely to effect the influence of small-scale turbulence upon the plankton, and consequently the organic matter continuum should be considered both in terms of biological and physical importance for the microplankton.…”

Section: Turbulencementioning

confidence: 99%

See 1 more Smart Citation

Heterogeneity in bacterioplankton abundance from 4.5 millimetre resolution sampling

Seymour¹,

Mitchell²,

Pearson³

et al. 2000

Aquat. Microb. Ecol.

View full text Add to dashboard Cite

A suite of pneumatically operated sampling devices was employed to investigate distributional patterns of marine bacteria at the millimetre scale. Spatial heterogeneity in bacterial abundance, or patchiness, was expressed as a coefficient of variation, and ranged from 5.5 to 75%. Discrete regions of enhanced bacterial abundance, as well as clear gradients in abundance across entire sample arrays were observed, with changes in bacterial abundance of up to 16-fold observed across a distance of 32 mm. The role of turbulence in influencing bacterial distribution patterns was examined in a series of laboratory experiments. Levels of heterogeneity were found to be up to 6.5 times higher in stirred than unstirred water samples under laboratory conditions. The gradients in bacterial abundance observed here suggest that small-scale processes operate within the marine microenvironment to create and maintain spatial structure in the bacterioplankton community. We suggest that previously hypothesised nanoscale 'hot spots' and microzones exist only as maxima within a continuously variable distribution of bacteria within the marine environment.

show abstract

Oceanographic implications of non-newtonian properties found in phytoplankton cultures

Cited by 80 publications

References 22 publications

Inhibition of copepod grazing by diatom exudates: a factor in the development of mucus aggregates?

Inhibition of copepod grazing by diatom exudates: a factor in the development of mucus aggregates?

Transparent exopolymer particles (TEP) in aquatic environments

Heterogeneity in bacterioplankton abundance from 4.5 millimetre resolution sampling

Contact Info

Product

Resources

About