| Registro completo |
| Provedor de dados: |
ArchiMer
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| País: |
France
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| Título: |
Methodology of light response curves: application of chlorophyll fluorescence to microphytobenthic biofilms
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| Autores: |
Herlory, Olivier
Richard, Pierre
Blanchard, Gerard
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| Data: |
2007-11
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| Ano: |
2007
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| Resumo: |
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.
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| Tipo: |
Text
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| Idioma: |
Inglês
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| Identificador: |
http://archimer.ifremer.fr/doc/2007/publication-3331.pdf
DOI:10.1007/s00227-007-0787-9
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| Editor: |
Springer
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| Relação: |
http://archimer.ifremer.fr/doc/00000/3331/
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| Formato: |
application/pdf
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| Fonte: |
Marine Biology (0025-3162) (Springer), 2007-11 , Vol. 153 , N. 1 , P. 91-101
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| Direitos: |
2007 Springer
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