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| Titel |
Light effects on the isotopic fractionation of skeletal oxygen and carbon in the cultured zooxanthellate coral, Acropora: implications for coral-growth rates |
| VerfasserIn |
A. Juillet-Leclerc, S. Reynaud |
| 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 ; 7, no. 3 ; Nr. 7, no. 3 (2010-03-08), S.893-906 |
| Datensatznummer |
250004583
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| Publikation (Nr.) |
 copernicus.org/bg-7-893-2010.pdf |
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| Zusammenfassung |
Skeletal isotopic and metabolic measurements of the
branching coral Acropora cultured in constant conditions and subjected to two light
intensities were revisited. We individually compared the data recorded at
low light (LL) and high light (HL) for 24 colonies, all derived from the
same parent colony. Metabolic and isotopic responses to the different light
levels were highly variable. High light led to productivity enhancement,
reduction of surface extension, doubling of aragonite deposited weight and
increased δ18O levels in all nubbins; responses in
respiration and δ13C were not clear. The partitioning of the
colonies cultured at HL into two groups, one showing a δ13C
enrichment and the other a δ13C decrease revealed common
behaviors. Samples showing an increase in δ13C were associated
with the co-variation of low surface extension and high productivity while
samples showing a decrease in δ13C were associated with the
co-variation of higher surface extension and limited productivity.
This experiment, which allowed for the separation of temperature and light
effects on the coral, highlighted the significant light influences on both
skeletal δ18O and δ13C. The high scattering of
inter-colony δ18O observed at one site could be due to the
differing photosynthetic responses of symbiotic algal assemblages.
We compared our results with observations by Gladfelter on Acropora cervicornis (1982). Both set
of results highlight the relationships between coral-growth rates,
micro-structures and photosynthetic activity. It appears that extension
growth and skeleton thickening are two separate growth modes, and thickening
is light-enhanced while extension is light-suppressed. There are multiple
consequences of these findings for paleoclimatic reconstructions involving
corals. |
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