Photosynthetic responses of the coral Montipora digitata to cold temperature stress

Saxby, T., Dennison, W. C. and Hoegh-Guldberg, O. (2003) Photosynthetic responses of the coral Montipora digitata to cold temperature stress. Marine Ecology-progress Series, 248 85-97. doi:10.3354/meps248085

Author Saxby, T.
Dennison, W. C.
Hoegh-Guldberg, O.
Title Photosynthetic responses of the coral Montipora digitata to cold temperature stress
Journal name Marine Ecology-progress Series   Check publisher's open access policy
ISSN 1616-1599
Publication date 2003-01-01
Sub-type Article (original research)
DOI 10.3354/meps248085
Open Access Status DOI
Volume 248
Start page 85
End page 97
Total pages 13
Place of publication Oldendorf, Germany
Publisher Inter-Research
Language eng
Abstract Coral bleaching events have become more frequent and widespread, largely due to elevated sea surface temperatures. Global climate change could lead to increased variability of sea surface temperatures, through influences on climate systems, e.g. El Nino Southern Oscillation (ENSO). Field observations in 1999, following a strong ENSO, revealed that corals bleached in winter after unusually cold weather. To explore the basis for these observations, the photosynthetic responses of the coral species Montipora digitata Studer were investigated in a series of temperature and light experiments. Small replicate coral colonies were exposed to ecologically relevant lower temperatures for varying durations and under light regimes that ranged from darkness to full sunlight. Photosynthetic efficiency was analyzed using a pulse amplitude modulated (PAM) fluorometer (F-0, F-m, F-v/F-m), and chlorophyll a (chl a) content and symbiotic dinoflagellate density were analyzed with spectrophotometry and microscopy, respectively. Cold temperature stress had a negative impact on M digitata colonies indicated by decreased photosynthetic efficiency (F-v/F-m), loss of symbiotic dinoflagellates and changes in photosynthetic pigment concentrations. Corals in higher light regimes were more susceptible to cold temperature stress, Moderate cold stress resulted in photoacclimatory responses, but severe cold stress resulted in photodamage, bleaching and increased mortality. Responses to cold temperature stress of M digitata appeared similar to that observed in corals exposed to warmer than normal temperatures, suggesting a common mechanism. The results of this study suggest that corals and coral reefs may also be impacted by exposure to cold as well as warm temperature extremes as climate change occurs.
Keyword Ecology
Marine & Freshwater Biology
Coral Bleaching
Climate Change
Cold Temperature Stress
Symbiotic Dinoflagellates
Chlorophyll Fluorescence
Bleaching Event
Symbiotic Algae
Photochemical Efficiency
Q-Index Code C1

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Created: Wed, 15 Aug 2007, 05:15:09 EST