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In-line recording of PAM fluorescence of phytoplankton cultures as a new tool for studying effects of fluctuating nutrient supply on photosynthesis

Published online by Cambridge University Press:  18 May 2001

SEBASTIAN LIPPEMEIER ,
RALF HINTZE ,
KLAUS H. VANSELOW ,
PETER HARTIG  and
FRANCISCUS COLIJN
SEBASTIAN LIPPEMEIER
Affiliation:
Research and Technology Centre Westcoast of Kiel University, Hafentörn 1, 25761 Büsum, Germany
RALF HINTZE
Affiliation:
Research and Technology Centre Westcoast of Kiel University, Hafentörn 1, 25761 Büsum, Germany
KLAUS H. VANSELOW
Affiliation:
Research and Technology Centre Westcoast of Kiel University, Hafentörn 1, 25761 Büsum, Germany
PETER HARTIG
Affiliation:
Research and Technology Centre Westcoast of Kiel University, Hafentörn 1, 25761 Büsum, Germany
FRANCISCUS COLIJN
Affiliation:
Research and Technology Centre Westcoast of Kiel University, Hafentörn 1, 25761 Büsum, Germany
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Abstract

Turbidostat cultures of Dunaliella salina (Chlorophyceae) and Thalassiosira weissflogii (Bacillariophyceae) were grown at fluctuating concentrations of nitrate, phosphate and silicate. In-line measurements of PAM fluorescence were used to monitor the effects of fluctuating nutrient supply on the photochemical efficiency of photosystem II reaction centres of light-adapted cells (ΔF/F'm). Besides the maximal photochemical efficiency of photosystem II reaction centres of dark-adapted cells (Fv/Fm), chlorophyll a, particulate organic carbon, nitrogen and phosphorus, and the cell number were measured frequently during the experiments. Following nutrient-replete growth, the cells were supplied with medium from which either nitrate, phosphate or silicate was omitted. When significant effects of nutrient starvation were indicated by the fluorescence parameters, a pulse of the deficient nutrient was added to the cultures. Our experimental set-up for in-line fluorescence measurements provided sensitive and reproducible detection of the various fluorescence signals, revealing strong influences of nutrient supply on the photochemical efficiency of photosystem II. In general the fluorescence values changed substantially within 1–30 min after re-addition of the deficient nutrient. Addition of phosphate and silicate induced an immediate characteristic decrease in fluorescence, whereas nitrate addition was characterized by a strong, delayed increase in fluorescence. Complete recovery to pre-starvation fluorescence values took about 48 h in all experiments. The physiological background of nutrient uptake is used to explain the observed tight couplings between fluorescence responses and nutrient re-addition. Our study clearly demonstrates that in-line fluorescence measurements provide a new tool for the investigation of phytoplankton reactions to fluctuating nutrients and offer the possibility to detect nutrient starvation in the field.

Keywords

Dunaliella salinafluorescencein-line PAMnitrogennutrientsphosphorussiliconstarvationThalassiosira weissflogiiturbidostat
Type
Research Article
Information
European Journal of Phycology , Volume 36 , Issue 1 , February 2001 , pp. 89 - 100
Copyright
© 2001 British Phycological Society

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