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| Titel |
The last glacial-interglacial cycle in Lake Ohrid (Macedonia/Albania): testing diatom response to climate |
| VerfasserIn |
J. M. Reed, A. Cvetkoska, Z. Levkov, H. Vogel, B. Wagner |
| 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. 10 ; Nr. 7, no. 10 (2010-10-13), S.3083-3094 |
| Datensatznummer |
250005010
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| Publikation (Nr.) |
 copernicus.org/bg-7-3083-2010.pdf |
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| Zusammenfassung |
| Lake Ohrid is a site of global importance for palaeoclimate research. This
study presents results of diatom analysis of a ca. 136 ka sequence, Co1202,
from the northeast of the lake basin. It offers the opportunity to test
diatom response across two glacial-interglacial transitions and within the
Last Glacial, while setting up taxonomic protocols for future research. The
results are outstanding in demonstrating the sensitivity of diatoms to
climate change, providing proxy evidence for temperature change marked by
glacial-interglacial shifts between the dominant planktonic taxa,
Cyclotella fottii and C. ocellata, and exact correlation with geochemical proxies to mark the start of
the Last Interglacial at ca. 130 ka. Importantly, diatoms show much stronger
evidence in this site for warming during MIS3 than recorded in other
productivity-related proxies, peaking at ca. 39 ka, prior to the extreme
conditions of the Last Glacial maximum. In the light of the observed
patterns, and from the results of analysis of early Holocene sediments from
a second core, Lz1120, the lack of a response to Late Glacial and early
Holocene warming from ca. 14.7–6.9 ka suggests the Co1202 sequence may be
compromised during this phase. After ca. 7.4 ka, there is evidence for
enhanced nutrient enrichment compared to the Last Interglacial, followed by a post-Medieval loss of diversity which is consistent with cooling, but not definitive.
Taxonomically, morphological variability in C. fottii shows no clear trends linked to climate, but an intriguing change in central
area morphology occurs after ca. 48.7 ka, coincident with a tephra layer. In
contrast, C. ocellata shows morphological variation in the number of ocelli between
interglacials, suggesting climatically-forced variation or evolutionary
selection pressure. The application of a simple dissolution index does not
track preservation quality very effectively, underlining the importance of
diatom accumulation data in future studies. |
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