Photoinhibition and photoprotection in symbiotic dinoflagellates from reef-building corals

Hoegh-Guldberg, O. and Jones, R. J. (1999) Photoinhibition and photoprotection in symbiotic dinoflagellates from reef-building corals. Marine Ecology-progress Series, 183 73-86. doi:10.3354/meps183073

Author Hoegh-Guldberg, O.
Jones, R. J.
Title Photoinhibition and photoprotection in symbiotic dinoflagellates from reef-building corals
Journal name Marine Ecology-progress Series   Check publisher's open access policy
ISSN 0171-8630
Publication date 1999
Sub-type Article (original research)
DOI 10.3354/meps183073
Open Access Status DOI
Volume 183
Start page 73
End page 86
Total pages 14
Place of publication Oldendorf, Germany
Publisher Inter-Research
Language eng
Abstract Pulse-amplitude-modulation fluorometry and oxygen respirometry were used to investigate diel photosynthetic responses by symbiotic dinoflagellates to light levels in summer and winter on a high latitude coral reef. The symbiotic dinoflagellates from 2 species of reef-building coral (Porites cylindrica and Stylophora pistillata) showed photoinhibitory decreases in the ratio of variable (F-v) to maximal (F-m) fluorescence (F-v/F-m) as early as 09:00 h on both summer and winter days on the reefs associated with One Tree Island (23 degrees 30' S, 152 degrees 06' E; Great Barrier Reef, Australia). This was due to decreases in maximum, F-m, and to a smaller extent minimum, F-0, chlorophyll fluorescence. Complete recovery took 4 to 6 h and began to occur as soon as light levels fell each day. Chlorophyll fluorescence quenching analysis of corals measured during the early afternoon revealed classic regulation of photosystem II (PSII) efficiency through non-photochemical quenching (NPQ). These results appear to be similar to data collected for other algae and higher plants, suggesting involvement of the xanthophyll cycle of symbiotic dinoflagellates in regulating the quantum efficiency of PSII. The ability of symbiotic dinoflagellates to develop significant NPQ, however, depended strongly on when the symbiotic dinoflagellates were studied. Whereas symbiotic dinoflagellates from corals in the early afternoon showed a significant capacity to regulate the efficiency of PSII using NPQ, those sampled before sunrise had a slower and much reduced capacity, suggesting that elements of the xanthophyll cycle are suppressed prior to sunrise. A second major finding of this study is that the quantum efficiency of PSII in symbiotic dinoflagellates is strongly diurnal, and is as much as 50% lower just prior to sunrise than later in the day. When combined with oxygen flux data, these results indicate that a greater portion of the electron transport occurring later in the day is likely to be due to the increases in the rate of carbon fixation by Rubisco or to higher flutes through the Mehler-Ascorbate-Peroxidase (MAP) cycle.
Keyword Ecology
Marine & Freshwater Biology
Symbiotic Dinoflagellates
Chlorophyll Fluorescence
Colour Morphs
Solar Ultraviolet-radiation
Anemone Aiptasia-pulchella
Chlorophyll Fluorescence
Invertebrate Symbioses
Photooxidative Stress
Diadinoxanthin Cycle
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Centre for Marine Studies Publications
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Citation counts: TR Web of Science Citation Count  Cited 136 times in Thomson Reuters Web of Science Article | Citations
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Created: Mon, 13 Aug 2007, 11:17:34 EST