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| Titel |
Marine bivalve feeding strategy, radiocarbon ages and stable isotopes in Scottish coastal waters |
| VerfasserIn |
Elena Lo Giudice Cappelli, William Austin |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250144567
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| Publikation (Nr.) |
 EGU/EGU2017-8409.pdf |
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| Zusammenfassung |
| Marine bivalve molluscs have been widely used for palaeoenvironmental reconstructions as
their carbonate provides a direct chronology of environmental change through radiocarbon
dating, and their shell composition, particularly with regard to their oxygen and carbon stable
isotopes, is likely to reflect ambient seawater conditions. However, stable isotope signatures
of marine bivalve shells are difficult to interpret, as shell formation can be influenced by
secondary factors such as metabolic processes and feeding strategies. In radiocarbon ages,
uncertainty is introduced as bivalves inhabit a range of ecological niches which may
be of significance in the case of deep borrowing and deposit feeding bivalves, as
they could incorporate older carbon in their shells, resulting in apparent older ages
than the true age of the dissolved inorganic carbon in the overlying seawater. To
discriminate between the different factors influencing the composition of marine molluscs’
shells, we measured radiocarbon ages, oxygen and carbon stable isotopes in nine
species of marine bivalves having different known feeding strategies and inhabiting a
number of ecological niches; all shells being live-collected (between 1923-1925) from
six localities around the Scottish coast, a wider context than has been previously
undertaken. Our results show that in situ variability (i.e.: replicate measurements
of the same species at the same location) is generally low for both stable isotope
analyses and radiocarbon dates, indicating good accuracy of the measurements.
Intra-species (i.e.: same species - different location) and inter-species (i.e.: different
species – same location) variability is significant in stable isotopes measurements,
meaning that marine bivalve shells do record changes in the local environment
and are sensitive to different feeding strategies and ecological settings. In contrast,
radiocarbon ages do not change with location and are not sensitive to molluscs’ diets or
microhabitats, as all measured bivalve shells are the same age within the ± 2sigma error.
Thus, the main conclusion that can be drawn from our results is that stable isotopes
measured in marine bivalve shells can be a very useful source of palaeoenvironmental
information in coastal and continental shelf waters, while radiocarbon dating of the same
shells provides a reliable chronology of environmental change, regardless of vital
effects and differences in microhabitats, feeding strategies and sample location. |
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