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| Titel |
Technical Note: On methodologies for determining the size-normalised weight of planktic foraminifera |
| VerfasserIn |
C. J. Beer, R. Schiebel, P. A. Wilson |
| 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 ; 7, no. 7 ; Nr. 7, no. 7 (2010-07-16), S.2193-2198 |
| Datensatznummer |
250004897
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| Publikation (Nr.) |
 copernicus.org/bg-7-2193-2010.pdf |
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| Zusammenfassung |
| The size-normalised weight (SNW) of planktic foraminifera, a measure of test
wall thickness and density, is potentially a valuable palaeo-proxy for marine
carbon chemistry. As increasing attention is given to developing this proxy
it is important that methods are comparable between studies. Here, we compare
SNW data generated using two different methods to account for variability in
test size, namely (i) the narrow (50 μm range) sieve fraction method
and (ii) the individually measured test size method. Using specimens from the
200–250 μm sieve fraction range collected in multinet samples from
the North Atlantic, we find that sieving does not constrain size sufficiently
well to isolate changes in weight driven by variations in test wall thickness
and density from those driven by size. We estimate that the SNW data produced as part of this study are
associated with an uncertainty, or error bar, of about ±11%. Errors
associated with the narrow sieve fraction method may be reduced by decreasing
the size of the sieve window, by using larger tests and by increasing the
number tests employed. In situations where numerous large tests are
unavailable, however, substantial errors associated with this sieve method
remain unavoidable. In such circumstances the individually measured test size
method provides a better means for estimating SNW because, as our results
show, this method isolates changes in weight driven by variations in test
wall thickness and density from those driven by size. |
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