Chironomids as indicators of the Holocene climatic and environmental history of two lakes in Northeast Greenland |
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| Authors: | STEFFI SCHMIDT BERND WAGNER OLIVER HEIRI MARTIN KLUG OLE BENNIKE MARTIN MELLES |
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| Institution: | 1. Institute for Geology and Mineralogy, University of Cologne, Zülpicher Strasse 49a, D‐50674 Cologne, Germany;2. Institute for Plant Sciences and Oeschger Centre for Climate Change Research, University of Bern, Altenbergrain 21, CH‐3013 Bern, Switzerland;3. Palaeoecology, Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, The Netherlands;4. Geological Survey of Denmark and Greenland, ?ster Voldgade 10, DK‐1350 Copenhagen K, Denmark |
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| Abstract: | Schmidt, S., Wagner, B., Heiri, O., Klug, M., Bennike, O. & Melles, M. 2010: Chironomids as indicators of the Holocene climatic and environmental history of two lakes in Northeast Greenland. Boreas, 10.1111/j.1502‐3885.2010.00173.x. ISSN 0300‐9483. Two Holocene sediment sequences from arctic lakes on Store Koldewey, an island in Northeast Greenland, were investigated for fossil chironomid assemblages. A total of 18 and 21 chironomid taxa were identified in 290‐ and 252‐cm‐long sediment sequences from Duck Lake and Hjort Lake, respectively. The chironomid assemblages were very similar in the two lakes. Canonical correspondence analysis (CCA) was used to compare fossil chironomid assemblages from Store Koldewey with chironomid assemblages and environmental conditions presently found in Canadian Arctic lakes and, hence, to infer environmental changes for Northeast Greenland. The first chironomids appeared at c. 9500 cal. a BP in Hjort Lake, and 500 years later in Duck Lake. Taxa typical for cold and nutrient‐poor arctic lakes dominated the earliest assemblages. Chironomid assemblages with taxa typical of higher summer air temperatures and lakes with higher nutrient availability occur between 8000 and 5000 cal. a BP. This period probably marks the regional Holocene thermal maximum, which is relatively late compared with some palaeoenvironmental records from East Greenland. One possible reason could be the location of Store Koldewey at the very outer coast, with local climatic conditions strongly influenced by the cold East Greenland Current. From around 5000 cal. a BP, chironomid assemblages in Duck Lake and Hjort Lake again became more typical of those presently found in Northeast Greenland, indicating relatively cold and nutrient‐poor conditions. This shift coincides with an increase of ice‐rafting debris off East Greenland and an intensification of the East Greenland Current. |
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