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The last glacial-interglacial cycle in Lake Ohrid (Macedonia/Albania): testing diatom response to climate

Reed, J. M.; Cvetkoska, A.; Levkov, Z.; Vogel, H.; Wagner, B.

Authors

J. M. Reed

A. Cvetkoska

Z. Levkov

H. Vogel

B. Wagner



Abstract

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. 15-7.4 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, following by a post-Medieval cooling trend. 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 concentration data in future studies.

Citation

Reed, J. M., Cvetkoska, A., Levkov, Z., Vogel, H., & Wagner, B. The last glacial-interglacial cycle in Lake Ohrid (Macedonia/Albania): testing diatom response to climate. Biogeosciences Discussions, 7(10), 4689-4714. doi:10.5194/bgd-7-4689-2010

Journal Article Type Article
Online Publication Date Jun 17, 2010
Deposit Date Nov 13, 2014
Publicly Available Date Nov 13, 2014
Journal Biogeosciences discussions
Print ISSN 1810-6277
Electronic ISSN 1810-6285
Publisher European Geosciences Union
Peer Reviewed Peer Reviewed
Volume 7
Issue 10
Pages 4689-4714
DOI https://doi.org/10.5194/bgd-7-4689-2010
Keywords Earth-Surface Processes; Ecology, Evolution, Behavior and Systematics
Public URL https://hull-repository.worktribe.com/output/466007
Publisher URL http://www.biogeosciences.net/7/3083/2010/bg-7-3083-2010-discussion.html
Additional Information Copy of article: Biogeosciences Discuss., 7, 4689–4714, 2010 http://www.biogeosciences.net/7/3083/2010/bg-7-3083-2010-discussion.html

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