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| Titel |
A new conceptual model of coral biomineralisation: hypoxia as the physiological driver of skeletal extension |
| VerfasserIn |
S. 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. 5 ; Nr. 10, no. 5 (2013-05-02), S.2867-2884 |
| Datensatznummer |
250018226
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| Publikation (Nr.) |
 copernicus.org/bg-10-2867-2013.pdf |
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| Zusammenfassung |
| That corals skeletons are built of aragonite crystals with
taxonomy-linked ultrastructure has been well understood since the 19th
century. Yet, the way by which corals control this crystallization process
remains an unsolved question. Here, I outline a new conceptual model of
coral biomineralisation that endeavours to relate known skeletal features
with homeostatic functions beyond traditional growth (structural)
determinants. In particular, I propose that the dominant physiological
driver of skeletal extension is night-time hypoxia, which is exacerbated by
the respiratory oxygen demands of the coral's algal symbionts (= zooxanthellae). The model thus provides a new narrative to explain the high
growth rate of symbiotic corals, by equating skeletal deposition with the
"work-rate" of the coral host needed to maintain a stable and beneficial
symbiosis. In this way, coral skeletons are interpreted as a continuous
(long-run) recording unit of the stability and functioning of the
coral–algae endosymbiosis. After providing supportive evidence for the model
across multiple scales of observation, I use coral core data from the Great
Barrier Reef (Australia) to highlight the disturbed nature of the symbiosis
in recent decades, but suggest that its onset is consistent with a
trajectory that has been followed since at least the start of the 1900s. In
concluding, I outline how the proposed capacity of cnidarians (which
includes modern reef corals) to overcome the metabolic limitation of hypoxia
via skeletogenesis also provides a new hypothesis to explain the sudden
appearance in the fossil record of calcified skeletons at the
Precambrian–Cambrian transition – and the ensuing rapid appearance of most
major animal phyla. |
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