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| Titel |
Oxygen isotope ratios in the shell of Mytilus edulis: archives of glacier meltwater in Greenland? |
| VerfasserIn |
E. A. A. Versteegh, M. E. Blicher, J. Mortensen, S. Rysgaard, T. D. Als, A. D. Jr. Wanamaker |
| 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. 12 ; Nr. 9, no. 12 (2012-12-18), S.5231-5241 |
| Datensatznummer |
250007467
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| Publikation (Nr.) |
 copernicus.org/bg-9-5231-2012.pdf |
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| Zusammenfassung |
| Melting of the Greenland Ice Sheet (GrIS) is accelerating
and will contribute significantly to global sea level rise during the
21st century. Instrumental data on GrIS melting only cover the last few
decades, and proxy data extending our knowledge into the past are vital for
validating models predicting the influence of ongoing climate change. We
investigated a potential meltwater proxy in Godthåbsfjord (West
Greenland), where glacier meltwater causes seasonal excursions with lower
oxygen isotope water (δ18Ow) values and salinity. The blue
mussel (Mytilus edulis) potentially records these variations, because it precipitates its
shell calcite in oxygen isotopic equilibrium with ambient seawater. As M. edulis
shells are known to occur in raised shorelines and archaeological shell
middens from previous Holocene warm periods, this species may be ideal in
reconstructing past meltwater dynamics. We investigate its potential as a
palaeo-meltwater proxy. First, we confirmed that M. edulis shell calcite oxygen
isotope (δ18Oc) values are in equilibrium with ambient
water and generally reflect meltwater conditions. Subsequently we
investigated if this species recorded the full range of δ18Ow values occurring during the years 2007 to 2010. Results show
that δ18Ow values were not recorded at very low salinities
(< ~ 19), because the mussels appear to cease growing.
This implies that Mytilus edulis δ18Oc values are suitable in
reconstructing past meltwater amounts in most cases, but care has to be
taken that shells are collected not too close to a glacier, but rather in
the mid-region or mouth of the fjord. The focus of future research will
expand on the geographical and temporal range of the shell measurements by
sampling mussels in other fjords in Greenland along a south–north gradient,
and by sampling shells from raised shorelines and archaeological shell
middens from prehistoric settlements in Greenland. |
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