Differential coral bleaching—contrasting the activity and response of enzymatic antioxidants in symbiotic partners under thermal stress

Krueger, Thomas, Hawkins, Thomas D., Becker, Susanne, Pontasch, Stefanie, Dove, Sophie, Hoegh-Guldberg, Ove, Leggat, William, Fisher, Paul L. and Davy, Simon K. (2015) Differential coral bleaching—contrasting the activity and response of enzymatic antioxidants in symbiotic partners under thermal stress. Comparative Biochemistry and Physiology Part A: Molecular and Integrative Physiology, 190 15-25. doi:10.1016/j.cbpa.2015.08.012


Author Krueger, Thomas
Hawkins, Thomas D.
Becker, Susanne
Pontasch, Stefanie
Dove, Sophie
Hoegh-Guldberg, Ove
Leggat, William
Fisher, Paul L.
Davy, Simon K.
Title Differential coral bleaching—contrasting the activity and response of enzymatic antioxidants in symbiotic partners under thermal stress
Journal name Comparative Biochemistry and Physiology Part A: Molecular and Integrative Physiology   Check publisher's open access policy
ISSN 1531-4332
1095-6433
Publication date 2015-12-01
Year available 2015
Sub-type Article (original research)
DOI 10.1016/j.cbpa.2015.08.012
Open Access Status Not Open Access
Volume 190
Start page 15
End page 25
Total pages 11
Place of publication Philadelphia, PA United States
Publisher Elsevier
Language eng
Formatted abstract
Mass coral bleaching due to thermal stress represents a major threat to the integrity and functioning of coral reefs. Thermal thresholds vary, however, between corals, partly as a result of the specific type of endosymbiotic dinoflagellate (Symbiodinium sp.) they harbour. The production of reactive oxygen species (ROS) in corals under thermal and light stress has been recognised as one mechanism that can lead to cellular damage and the loss of their symbiont population (Oxidative Theory of Coral Bleaching). Here, we compared the response of symbiont and host enzymatic antioxidants in the coral species Acropora millepora and Montipora digitata at 28 °C and 33 °C. A. millepora at 33 °C showed a decrease in photochemical efficiency of photosystem II (PSII) and increase in maximum midday excitation pressure on PSII, with subsequent bleaching (declining photosynthetic pigment and symbiont density). M. digitata exhibited no bleaching response and photochemical changes in its symbionts were minor. The symbiont antioxidant enzymes superoxide dismutase, ascorbate peroxidase, and catalase peroxidase showed no significant upregulation to elevated temperatures in either coral, while only catalase was significantly elevated in both coral hosts at 33 °C. Increased host catalase activity in the susceptible coral after 5 days at 33 °C was independent of antioxidant responses in the symbiont and preceded significant declines in PSII photochemical efficiencies. This finding suggests a potential decoupling of host redox mechanisms from symbiont photophysiology and raises questions about the importance of symbiont-derived ROS in initiating coral bleaching.
Keyword APX
Acropora millepora
CAT
Global change
Montipora digitata
Oxidative stress
SOD
Symbiodinium
Symbiosis
Thermal biology
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

 
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