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Methodology of light response curves: application of chlorophyll fluorescence to microphytobenthic biofilms
- Source :
- Marine Biology, 153(1), 91-101. Springer Verlag GmbH, Marine Biology (0025-3162) (Springer), 2007-11, Vol. 153, N. 1, P. 91-101, Marine Biology
- Publication Year :
- 2007
- Publisher :
- Springer Science and Business Media LLC, 2007.
-
Abstract
- The light response curve methodology for microphytobenthic biofilms was studied by comparing the two most usual approaches used in pulse amplitude modulated (PAM) fluorometry. The non-sequential light curve (N-SLC) method is characterized by independent measures of the photosynthetic activity across a light gradient whereas the rapid light curve (RLC) method consists of successive measures on the same sample exposed to a stepwise increase of light intensities. Experiments were carried out on experimental microphytobenthic biofilms prepared from natural assemblages and acclimated to dark conditions. In preliminary experiments, N-SLCs were constructed from fluorescence induction curves performed at 12 different photon flux densities (PFDs). A minimum of 50 s of illumination was necessary to reach a stable light response curve; shorter illumination times resulted in underestimating the physiological parameters (alpha the light utilization coefficient in light-limited conditions and rETR(max) the maximum rate of photosynthesis efficiency) of the light response curve. For the comparison between N-SLCs and RLCs, the same time of illumination (50 s) was used for each light step of RLCs so that N-SLCs differed from RLCs only by the way the amount of light was delivered, i.e., a light dose accumulation for RLC. The experimental results showed the difference between the two photobiological response curves. In the lower range of PFDs, RLCs exhibited a larger value of alpha; in this light-limited part of the response curve the incremental increase of PFDs limited the development of NPQ and resulted in a better optimization of electron transport rate for RLC. In the higher range of PFDs, the trend was reversed and the RLC showed a lower value of rETR(max) than the N-SLC did; this is attributed to the light dose accumulation which likely led to a more efficient dispersion of energy, as illustrated by a higher non-photochemical quenching (NPQ). In conclusion, these results confirm that parameters derived from both methods differ in their value and do not bear the same physiological information.
- Subjects :
- 0106 biological sciences
Analytical chemistry
Pulse Amplitude Modulate
Aquatic Science
Photosynthetic efficiency
Biology
Photosynthesis
01 natural sciences
Fluorescence spectroscopy
chemistry.chemical_compound
Dispersion (optics)
Microalgae
Light Response Curve
Chlorophyll fluorescence
Ecology, Evolution, Behavior and Systematics
Ecology
010604 marine biology & hydrobiology
Light curve
Fluorescence
Light Curve
chemistry
Chlorophyll
Photochemical Efficiency
Research Article
010606 plant biology & botany
Subjects
Details
- ISSN :
- 14321793 and 00253162
- Volume :
- 153
- Database :
- OpenAIRE
- Journal :
- Marine Biology
- Accession number :
- edsair.doi.dedup.....5f81110aa339920d2adce7d15bcea69c