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| Titel |
Benthic buffers and boosters of ocean acidification on coral reefs |
| VerfasserIn |
K. R. N. Anthony, G. Diaz-Pulido, N. Verlinden, B. Tilbrook, A. J. Andersson |
| 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. 7 ; Nr. 10, no. 7 (2013-07-19), S.4897-4909 |
| Datensatznummer |
250018351
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| Publikation (Nr.) |
 copernicus.org/bg-10-4897-2013.pdf |
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| Zusammenfassung |
| Ocean acidification is a threat to marine ecosystems globally. In
shallow-water systems, however, ocean acidification can be masked by benthic
carbon fluxes, depending on community composition, seawater residence time,
and the magnitude and balance of net community production (NCP) and
calcification (NCC). Here, we examine how six benthic groups from a coral
reef environment on Heron Reef (Great Barrier Reef, Australia) contribute to
changes in the seawater aragonite saturation state (Ωa).
Results of flume studies using intact reef habitats (1.2 m by 0.4 m),
showed a hierarchy of responses across groups, depending on CO2 level,
time of day and water flow. At low CO2 (350–450 μatm),
macroalgae (Chnoospora implexa), turfs and sand elevated
Ωa of the flume water by around 0.10 to 1.20 h−1 –
normalised to contributions from 1 m2 of benthos to a 1 m deep water
column. The rate of Ωa increase in these groups was doubled
under acidification (560–700 μatm) and high flow (35 compared to
8 cm s−1). In contrast, branching corals (Acropora aspera)
increased Ωa by 0.25 h−1 at ambient CO2
(350–450 μatm) during the day, but reduced Ωa
under acidification and high flow. Nighttime changes in Ωa
by corals were highly negative (0.6–0.8 h−1) and exacerbated by
acidification. Calcifying macroalgae (Halimeda spp.) raised
Ωa by day (by around 0.13 h−1), but lowered
Ωa by a similar or higher amount at night. Analyses of
carbon flux contributions from benthic communities with four different
compositions to the reef water carbon chemistry across Heron Reef flat and
lagoon indicated that the net lowering of Ωa by
coral-dominated areas can to some extent be countered by long water-residence
times in neighbouring areas dominated by turfs, macroalgae and carbonate
sand. |
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