TY - JOUR
T1 - Pediastrum algae from the classic late glacial Bølling Sø site, Denmark: Response of aquatic biota to climate change
AU - Sarmaja-Korjonen, Kaarina
AU - Seppänen, Anna
AU - Bennike, Ole
N1 - Funding Information:
We would like to dedicate this paper to the memory of the late Helle Nielsen who helped and encouraged A. S. with identification. We wish to thank Bent Odgaard, Peter Rasmussen, Klaus Brodersen, Allan Køtter Hansen, and Hartmut Usinger for their help with the field work. The AMS dates were performed under the supervision of Jan Heinemeier, Aarhus University. This study was supported by the Danish Natural Science Research Council. A grant from the Emil Aaltonen Foundation to K. S.-K. is gratefully acknowledged, as well as a grant from the Finnish–Danish Cultural Foundation to K. S.-K. and A .S. We also wish to thank the two anonymous reviewers for their comments.
PY - 2006/3
Y1 - 2006/3
N2 - The late glacial and the early Holocene sediments of the classic site Bølling Sø in Denmark are being reinvestigated by multi-proxy analyses. We present here the record of Pediastrum species and discuss the climate-mediated changes in the aquatic ecosystem, as reflected by aquatic proxies (e.g. aquatic plants and mosses, cladocerans, ostracods, bryozoan statoblasts), as well as a number of other proxies (organic content, biogenic silica, carbonates, terrestrial plant macrofossils). Climate had warmed to such an extent at c. 12,500 14C yrs BP that aquatic life could begin. Productivity was low and only very scarce indication of a warmer interval predating the Allerød chronozone was found. At the beginning of the Allerød chronozone climate ameliorated and productivity clearly increased. The cool climate of the Younger Dryas chronozone (YD) was more clearly reflected in the terrestrial ecosystem than in the aquatic ecosystem, where productivity appeared to remain rather high. The lake was very shallow and non-stratified during the YD, indicating low effective moisture. Probably it warmed throughout early in the open-water season and in that way enabled higher productivity, even if summer temperatures were rather low. It is also possible that the difference in July temperatures between the late part of the Allerød chronozone and the YD was not large in central Jutland. The amelioration of climate at the beginning of the Holocene is clearly reflected in all proxies. There is also evidence that the lake level rose. The lake probably remained alkaline during all of its history but some evidence suggests that pH was somewhat lowered during the YD chronozone. Pediastrum species appear to be relatively good indicators of environmental conditions; similarly, the concentrations may reflect productivity variations during changing climatic conditions.
AB - The late glacial and the early Holocene sediments of the classic site Bølling Sø in Denmark are being reinvestigated by multi-proxy analyses. We present here the record of Pediastrum species and discuss the climate-mediated changes in the aquatic ecosystem, as reflected by aquatic proxies (e.g. aquatic plants and mosses, cladocerans, ostracods, bryozoan statoblasts), as well as a number of other proxies (organic content, biogenic silica, carbonates, terrestrial plant macrofossils). Climate had warmed to such an extent at c. 12,500 14C yrs BP that aquatic life could begin. Productivity was low and only very scarce indication of a warmer interval predating the Allerød chronozone was found. At the beginning of the Allerød chronozone climate ameliorated and productivity clearly increased. The cool climate of the Younger Dryas chronozone (YD) was more clearly reflected in the terrestrial ecosystem than in the aquatic ecosystem, where productivity appeared to remain rather high. The lake was very shallow and non-stratified during the YD, indicating low effective moisture. Probably it warmed throughout early in the open-water season and in that way enabled higher productivity, even if summer temperatures were rather low. It is also possible that the difference in July temperatures between the late part of the Allerød chronozone and the YD was not large in central Jutland. The amelioration of climate at the beginning of the Holocene is clearly reflected in all proxies. There is also evidence that the lake level rose. The lake probably remained alkaline during all of its history but some evidence suggests that pH was somewhat lowered during the YD chronozone. Pediastrum species appear to be relatively good indicators of environmental conditions; similarly, the concentrations may reflect productivity variations during changing climatic conditions.
KW - Aquatic ecosystem
KW - Bølling Sø
KW - Climate
KW - Denmark
KW - Late glacial
KW - Pediastrum
UR - http://www.scopus.com/inward/record.url?scp=33644756423&partnerID=8YFLogxK
U2 - 10.1016/j.revpalbo.2005.12.003
DO - 10.1016/j.revpalbo.2005.12.003
M3 - Article
SN - 0034-6667
VL - 138
SP - 95
EP - 107
JO - Review of Palaeobotany and Palynology
JF - Review of Palaeobotany and Palynology
IS - 2
ER -