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| Titel |
Spatial linkages between coral proxies of terrestrial runoff across a large embayment in Madagascar |
| VerfasserIn |
C. A. Grove, J. Zinke, T. Scheufen, J. Maina, E. Epping, W. Boer, B. Randriamanantsoa, G.-J. A. Brummer |
| 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 ; 9, no. 8 ; Nr. 9, no. 8 (2012-08-10), S.3063-3081 |
| Datensatznummer |
250007236
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| Publikation (Nr.) |
 copernicus.org/bg-9-3063-2012.pdf |
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| Zusammenfassung |
| Coral cores provide vital climate reconstructions for
site-specific temporal variability in river flow and sediment load. Yet,
their ability to record spatial differences across multiple catchments is
relatively unknown. Here, we investigate spatial linkages between four coral
proxies of terrestrial runoff and their relationships between sites. Coral
cores were drilled in and around Antongil Bay, the largest bay in
Madagascar, and individually analysed for fifteen years of continuous
luminescence (G / B), Ba / Ca, δ18Osw and δ13C
data. Each coral core was drilled close to individual river mouths (≥ 7 km),
and proxy data were compared to modelled river discharge and sediment
runoff data for the three corresponding catchments. A reasonable agreement
between terrestrial runoff proxies with modelled river discharge and
sediment yield was observed. Some inconsistencies between proxy and modelled
data are likely linked to proxy behaviour, watershed size and local
environmental physiochemical parameters. In general, the further a coral
resided from its river source, the weaker the proxy relationship was with
modelled data and other corals, due to mixing gradients and currents.
Nevertheless, we demonstrate that two coral Ba / Ca and luminescence (G / B)
records influenced by the same watershed are reproducible. Furthermore, a
strong Ba / Ca relationship was observed between two cores from distant
watersheds, with baseline averages in agreement with modelled sediment
runoff data. As humic acids behave conservatively in the water column,
luminescence (G / B) data gave the highest regional correlations between
cores, and showed the most consistent relationship with site specific
modelled discharge. No statistical relationship was observed between cores
in terms of interannual δ18Osw and δ13C,
meaning corals were recording a localised signal at their respective sites,
confounded by vital effects. Comparing proxy baseline averages and mean
seasonal cycles provided a good overview of the runoff dynamics of the bay
system. |
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