Improved fluorescent microscopy for measuring the standing stock of phytoplankton including fragile components

Tsuji, Takashi; Yanagita, Tomomichi

doi:10.1007/bf00397110

Cited by 52 publications

(24 citation statements)

References 10 publications

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“…Physiological condition was determined by the fluorescence of individual cells within the colonies. Phytoplankton lose their autofluorescence when in poor condition; reductions of 30 % immediately upon death and 75 % 24 h after death have been reported (Tsuji & Yanagita 1981). Healthy P. pouchetii populations normally form lobed colonies with individual cells showing medium-bright, red-orange autofluorescence, while cells from unhealthy colonies lose fluorescence and individual colonies become depleted of cells, the latter due either to cell death or to transformation to the motile stage (Verity et al 1988).…”

Section: Methodsmentioning

confidence: 99%

Predation by copepods upon natural populations of Phaeocystis pouchetii as a function of the physiological state of the prey

Estep¹,

Nejstgaard²,

Skjoldal³

et al. 1990

Mar. Ecol. Prog. Ser.

117

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Confl~chng data have been previously presented on the ablllty of copepods to prey upon the prymneslophyte Phaeocystls pouchetu Whde some have suggested that gelatinous colonies of thls species c o n t a n blochemlcal substances that prevent t h e~r consumption others have shown that both slngle cells and colon~es of P pouchetu can serve as an excellent food source The present study presents data from feedlng expenments uslng 4 specles of copepods and natural samples of phytoplankton prey from a south-north transect dunng May 1989 in the Barents Sea Natural phytoplankton contalned P pouchefn colonies m assoclatlon w t h varylng amounts of diatoms Along the transect these colonies vaned from h~g h l y fluorescent and healthy In the north to weakly fluorescent In the south Results of expenments uslng both image analysis and radiotracer techniques indicate that diatoms were actlvely preyed upon In all expenments w t h long-chain-formlng species as the preferred food Predahon upon P pouchefn colon~es was dependent upon the physiological condition of the colonies Healthy colonies were not consumed, while suscephble colon~es were consumed at rates 2 to 10 tlmes those for chain-forrmng dlatoms The selective predalon descnbed here has important impl~cations for specles composition in Archc waters

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Section: Methodsmentioning

confidence: 99%

Predation by copepods upon natural populations of Phaeocystis pouchetii as a function of the physiological state of the prey

Estep¹,

Nejstgaard²,

Skjoldal³

et al. 1990

Mar. Ecol. Prog. Ser.

117

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show abstract

“…Competition experiments were sampled approximately every three days. Samples were fixed with a paraformaldehyde-glutaraldehyde solution (Tsuji and Yanagita 1981). The population densities in these species mixtures were analyzed with the EurOPA flow cytometer (Dubelaar et al 1989, Jonker et al 1995.…”

Section: Sampling and Countingmentioning

confidence: 99%

Competition for Light between Phytoplankton Species: Experimental Tests of Mechanistic Theory

Huisman¹,

Jonker²,

Zonneveld³

et al. 1999

Ecology

112

168

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Abstract. According to recent competition theory, the population dynamics of phytoplankton species in monoculture can be used to make a priori predictions of the dynamics and outcome of competition for light. The species with lowest ''critical light intensity'' should be the superior light competitor. To test this theory, we ran monoculture experiments and competition experiments with two green algae (Chlorella vulgaris and Scenedesmus protuberans) and two cyanobacteria (Aphanizomenon flos-aquae and a Microcystis strain) in light-limited continuous cultures. We used the monoculture experiments to estimate the critical light intensities of the species. Scenedesmus had by far the highest critical light intensity. The critical light intensities of Chlorella, Aphanizomenon, and Microcystis were rather similar. According to observation, Aphanizomenon had a slightly lower critical light intensity than Chlorella and Microcystis. However, according to a model fit to the monoculture experiments, Chlorella had a slightly lower critical light intensity than Microcystis, which in turn had a slightly lower critical light intensity than Aphanizomenon. These subtle differences between observed and fitted critical light intensities could be attributed to differences in the light absorption spectra of the species. The competition experiments were all consistent with the competitive ordering of the species according to the fitted critical light intensities: Chlorella displaced all three other species, Microcystis displaced both Aphanizomenon and Scenedesmus, and Aphanizomenon only displaced Scenedesmus. Not only the final outcomes, but also the time courses of competition predicted by the theory, were in excellent agreement with the experimental results for nearly all species combinations.

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“…Samples (1 ml) preserved with a mix of glutaraldehyde and formaldehyde (Tsuji and Yanagita 1981) were filtered onto a 0.02-m, 25-mm Whatman Anodisc filter and stained using a mixture of SYBR I and SYBR II green (Molecular Probes) fluorescent DNA and RNA markers, respectively (final dilution 4 ϫ 10 Ϫ3 v/v each). The filters were then mounted between a slide and cover slip using Aquapolymount (Polysciences).…”

Section: Methodsmentioning

confidence: 99%

Water column interleaving: A new physical mechanism determining protist communities and bacterial states

Lovejoy

Carmack²,

Legendre

et al. 2002

Limnology & Oceanography

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During a spring-summer bloom in a large Arctic polynya, vertically distinct protist communities (phytoplankton and protozoa) occurred within layers caused by interleaving and entrainment of different water masses. We developed a ternary community distance index to quantify the variability in protist community structure in these heterogeneous surface layers. This index was highly correlated (r ϭ 0.984, n ϭ 6) with the extent of physical interleaving (quantified as the root mean square deviations in temperature between measured and smoothed profiles) indicating a high degree of physical-biotic coupling within water columns of the polynya. Water mass layering created favorable conditions for ciliate blooms. These blooms were associated with distinct temperature-salinity layers. These layers might act as processing traps for particulate organic matter, with highest concentrations of viruses and bacteria (specifically cells with open or leaky membranes, suggesting microbial grazing pressure) occurring in highly interleaved water columns. In contrast, viral and bacterial concentrations were lowest at a noninterleaved station where protist biomass was dominated by flagellates and small dinoflagellates that were evenly distributed down the water column. Water mass interleaving is likely to contribute to microbial biodiversity, community structure and vertical segmentation of biogeochemical processes in the upper ocean.Water masses can be defined by their temperature (T) and salinity (S) characteristics, which are determined by atmosphere-ocean interactions and freshwater input from rivers or ice melt. Once formed, the waters can be transported away from their site of origin and can be tracked by their distinct

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Improved fluorescent microscopy for measuring the standing stock of phytoplankton including fragile components

Cited by 52 publications

References 10 publications

Predation by copepods upon natural populations of Phaeocystis pouchetii as a function of the physiological state of the prey

Predation by copepods upon natural populations of Phaeocystis pouchetii as a function of the physiological state of the prey

Competition for Light between Phytoplankton Species: Experimental Tests of Mechanistic Theory

Water column interleaving: A new physical mechanism determining protist communities and bacterial states

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