A system for measuring phytoplankton photosynthesis in a defined light field with an oxygen electrode

Dubinsky, Zvy; Falkowski, Paul G.; Post, Anton F.; Hes, Udo M. van

doi:10.1093/plankt/9.4.607

Cited by 127 publications

(73 citation statements)

References 5 publications

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“…The advantages of the Photosynthetic Light Dispensation System over the microelectrode method and the bell jar technique, however, is the precise control of environmental conditions such as irradiance and temperature, the supply of reproducible, rapid measurements of P-E curves and the measurement of physiological parameters in all requested light modes, predetermined by the computer. The latter is a new function, not included in a similar system described by Dubinsky et al (1987). Additionally, there is the advantage of online-monitoring of the measurements, and data analysis is quite simple and rapid, because all data are immediately transferred to the connected computer, on which they are analysed by the integrated software and can be further processed by common calculation programs.…”

Section: Application Of the Methodsmentioning

confidence: 99%

“…However, this method does not allow reproducible measurements under controlled environmental conditions. These are considered to be important for comparing photosynthetic capacities of algal populations by Dubinsky et al (1987), who describe a system for measuring phytoplankton photosynthesis in a defined irradiance field with an oxygen electrode. In the present study, a comparable system, a so-called 'Light Dispensation System' in combination with a Clark-type electrode, was used to determine oxygen production of benthic algae.…”

Section: Introductionmentioning

confidence: 99%

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The Photosynthetic Light Dispensation System:application to microphytobenthic primary production measurements

Wolfstein¹,

Hartig²

1998

Mar. Ecol. Prog. Ser.

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Measurements of rnicrophytobenthos primary production were carried out in the German Wadden Sea in order to test the application of a 'Photosynthetic Light Dispensation System', which was originally developed for photosynthetic research of higher plants. A description of the computercontrolled system, consisting mainly of a subunit providing the irradiance (photosynthetically active radiation, PAR), and a subunit equipped with a Clark-type electrode for measuring oxygen production and respiration processes is given. The system allows rapid and reproducible measurements of photosynthesis-irradiance (P-E) curves at light modes predetermined by the computer and simple, rapid data analysis. Additionally, P-E curves obtained by this system were compared to those received by simultaneously conducted 'T measurements. Primary production measured by the oxygen method was on average 2.00 times higher than the values obtained by the "C method. Production rates varied between 1.7 and 4.1 mg C mg chl a-' h-' with a mean of 2.75 mg C mg chl a-' h-'

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Section: Application Of the Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Photosynthetic Light Dispensation System:application to microphytobenthic primary production measurements

Wolfstein¹,

Hartig²

1998

Mar. Ecol. Prog. Ser.

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“…The rate of photosynthetic oxygen production was made with an apparatus similar to that described by Dubinsky et al (1987) suspension between 3-mm thick glass windows. It was illuminated by a Kodak slide projector with a 250-W tungsten-halogen bulb (Osram) 260 mm from the front of the chamber.…”

Section: Measurements Of Photosynthetic Oxygen Production and Irradiancementioning

confidence: 99%

The daily integral of growth by Planktothrix rubescens calculated from growth rate in culture and irradiance in Lake Zürich

2000

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In Lake Zu$ rich, populations of the cyanobacterium Planktothrix rubescens develop in the metalimnion during the summer and become gradually entrained in the deepening surface mixed layer during the autumn. It had previously been demonstrated that the daily integrals of photosynthetic production accounted for the growth observed in the metalimnion and greatly exceeded the smaller increase during the autumn. We have now determined the relationship between growth rate (µ) and irradiance (I ) in cultures of P. rubescens strain Pla 9316 maintained at 20mC on a 12 : 12 h light : dark cycle : the highest net growth rate averaged over the 24 h (µ h ) was 0.123 d −" , the dark rate (µ D ) was k0.020 d −" , the gross rate (φ m l µ h kµ D ) was 0.144 d −" , the affinity coefficient (α) was 0.0273 (d µmol m −# s −" ) −" and the compensation point (I C ) was 1.76 µmol m −# s −" . Using the corresponding coefficients calculated for the light period (µ Lh l 0.267 d −" , φ Lm l 0.287 d −" and α L l 0.0547 (d µmol m −# s −" ) −" ), instantaneous growth rates could be calculated from the irradiance. Comparison with growth rates at 10mC indicated a Q "! of 1.48. These coefficients were used in a modification of the Smith equation to calculate potential growth rates of Planktothrix from the irradiance and temperature at each time and depth in Lake Zu$ rich. Data on irradiance, vertical light attenuation and temperature were used to calculate the daily integrals of biomass increase over a period of 136 d. These growth integrals gave a closer correspondence to the observed population increase than the photosynthetic integrals calculated previously from measurements made with lakewater samples dominated by Planktothrix. Photosynthetic measurements made with the Planktothrix culture indicated a maximum rate of carbon increase (0.467 d −" ) that exceeds the maximum growth rate, which suggests that other factors limit growth over long periods.

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“…Rates of photosynthetic O # production were measured with a Clark O # electrode mounted in a magnetically stirred chamber illuminated with a light beam from a halogen lamp passed through neutral density filters in a slide projector (Dubinsky et al, 1987). With each filter, the mean photon irradiance in the chamber was calculated as I m l (I !…”

Section: Measurements Of Photosynthesismentioning

confidence: 99%

The daily integral of photosynthesis by Planktothrix rubescens during summer stratification and autumnal mixing in Lake Zürich

1998

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It has been suggested that the populations of planktonic cyanobacteria that occupy the metalimnion of stratified lakes during the summer months may be aestivating between the main periods of growth during entrainment in the epilimnion in spring and summer. We determined the vertical distribution of the biomass and daily integral of photosynthesis of the population of Planktothrix (Oscillatoria) rubescens in Lake Zu$ rich for 136 d from July to November 1995. The population showed an 80-fold increase during the stratified period but it only doubled over the subsequent period of entrainment. During the first eight days, part of the increase was attributed to recruitment of filaments floating up from greater depths but all of the subsequent production could be accounted for by photoautotrophic growth. On sunny days the biomass-specific photosynthesis of this population reached some of the highest values over the whole period despite its depth ( 13 m). On very cloudy days, however, primary productivity was very low and on 4 days, when the mean depth of the population exceeded 15 m, there was no net production. Over the whole period of the study, the accumulated photosynthetic production exceeded the increase in biomass of the population by a factor of 9n5. Although much of this production occurred during the period of entrainment only a small proportion was translated into growth of the population. It is concluded that the growth that takes place in the period of stratification in the metalimnion is essential to subsequent production.

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A system for measuring phytoplankton photosynthesis in a defined light field with an oxygen electrode

Cited by 127 publications

References 5 publications

The Photosynthetic Light Dispensation System:application to microphytobenthic primary production measurements

The Photosynthetic Light Dispensation System:application to microphytobenthic primary production measurements

The daily integral of growth by Planktothrix rubescens calculated from growth rate in culture and irradiance in Lake Zürich

The daily integral of photosynthesis by Planktothrix rubescens during summer stratification and autumnal mixing in Lake Zürich

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