Photosynthesis Research

, Volume 83, Issue 3, pp 343–361

Estimation of chlorophyll content and daily primary production of the major algal groups by means of multiwavelength-excitation PAM chlorophyll fluorometry: performance and methodological limits

Authors

    • Biology I/Plant PhysiologyUniversity of Leipzig
  • Ulrich Schreiber
    • Julius-von-Sachs Institute of Biosciences, Botany IUniversity of Wuerzburg
  • Volker Kirchesch
    • German Federal Institute of Hydrology
  • Uwe Langner
    • Biology I/Plant PhysiologyUniversity of Leipzig
  • Christian Wilhelm
    • Biology I/Plant PhysiologyUniversity of Leipzig
Article

DOI: 10.1007/s11120-005-1329-2

Cite this article as:
Jakob, T., Schreiber, U., Kirchesch, V. et al. Photosynth Res (2005) 83: 343. doi:10.1007/s11120-005-1329-2

Abstract

The performance and methodological limits of the Phyto-PAM chlorophyll fluorometer were investigated with laboratory grown algae cultures and natural phytoplankton from the rivers Saar and Saale. The Phyto-PAM is a 4-wavelength chlorophyll fluorometer with the functional combination of chlorophyll (Chl) estimation and assessment of photosynthetic activity, both differentiated into the main algal groups. The reliability of fluorescence-based Chl estimation strongly depends on the group specific calibration of the instrument and the resulting chlorophyll/fluorescence (Chl/F) ratios in reference algal cultures. A very high reliability of the Chl estimation was obtained in the case of constant Chl/F-ratios. Algae grown at different light intensities showed marked differences in Chl/F-ratios, reflecting differences in pigment composition and Chl a specific absorption (a*). When the Phyto-PAM was calibrated with laboratory grown diatoms, the Chl a in river grown diatoms was underestimated, due a lower content of accessory pigments and stronger pigment packaging. While this aspect presently limits the application of PAM fluorometry in limnology, this limitation may be overcome by future technical progress in the detection of dynamic changes in Chl/F-ratio via fluorescence-based measurements of the functional PS II absorption cross-section. Practically identical Chl/F-ratios were found for the diatom-dominated waters of the rivers␣Saar and Saale, suggesting that the same instrument calibration parameters may be applied for hydrographically similar surface waters. For this particular case, despite of the present methodological limitations, the potential of PAM fluorometry in limnology could be demonstrated. Light response curves were measured to estimate primary production with a spectrally resolved model in daily courses at two sampling sites. Fluorescence based primary production was closely correlated with measured oxygen evolution rates until midday. In the afternoon, at the water surface the fluorescence approach gave higher␣rates than the measured oxygen evolution. Possible explanations for the observed differences are discussed.

Keywords

chlorophyll estimationchlorophyll fluorescencelight adaptationlight response curvesmodellingPhyto-PAMphytoplanktonprimary production

Abbreviations

a*

chlorophyll aspecific absorption;

Chl

chlorophyll

ETR

relative electron transport rate

F

fluorescence yield

F′m

maximal fluorescence yield of illuminated sample

ΦPS II

Photosytem II quantum yield

IK

PAR-value characteristic for light saturation

LED

light-emitting diode

LL

low light

ML

medium light

PAM

pulse amplitude modulation

PAR

photosynthetically active radiation

Pmax

maximal rate of photosynthesis

PP

primary production

PS

photosystem

Qphar

absorbed pho-tosynthetically active radiation

RLC

rapid light curves

σPS II

functional absorption cross section of Photosystem II

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© Springer 2005