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| Titel |
Breakdown of the coral-algae symbiosis: towards formalising a linkage between warm-water bleaching thresholds and the growth rate of the intracellular zooxanthellae |
| VerfasserIn |
S. A. Wooldridge |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 3 ; Nr. 10, no. 3 (2013-03-12), S.1647-1658 |
| Datensatznummer |
250018146
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| Publikation (Nr.) |
 copernicus.org/bg-10-1647-2013.pdf |
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| Zusammenfassung |
| Impairment of the photosynthetic machinery of the algal endosymbiont
("zooxanthellae") is the proximal driver of the thermal breakdown of the
coral-algae symbiosis ("coral bleaching"). Yet, the initial site of damage,
and early dynamics of the impairment are still not well resolved. In this
perspective essay, I consider further a recent hypothesis which proposes an
energetic disruption to the carbon-concentrating mechanisms (CCMs) of the
coral host, and the resultant onset of CO2-limitation within the
photosynthetic "dark reactions" as a unifying cellular mechanism. The
hypothesis identifies the enhanced retention of photosynthetic carbon for
zooxanthellae (re)growth following an initial irradiance-driven expulsion
event as a strong contributing cause of the energetic disruption. If true,
then it implies that the onset of the bleaching syndrome and setting of
upper thermal bleaching limits are emergent attributes of the coral
symbiosis that are ultimately underpinned by the characteristic growth
profile of the intracellular zooxanthellae; which is known to depend not
just on temperature, but also external (seawater) nutrient availability and
zooxanthellae genotype. Here, I review this proposed bleaching linkage at a
variety of observational scales, and find it to be parsimonious with the
available evidence. Future experiments are suggested that can more formally
test the linkage. If correct, the new cellular model delivers a valuable new
perspective to consider the future prospects of the coral symbiosis in an
era of rapid environmental change, including: (i) the underpinning mechanics
(and biological significance) of observed changes in resident zooxanthellae
genotypes, and (ii) the now crucial importance of reef water quality in
co-determining thermal bleaching resistance. |
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