A 40,000-year record of environmental change from ancient Lake Ohrid (Albania and Macedonia) |
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Authors: | Bernd Wagner André F Lotter Norbert Nowaczyk Jane M Reed Antje Schwalb Roberto Sulpizio Verushka Valsecchi Martin Wessels Giovanni Zanchetta |
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Institution: | 1.Institut für Geologie und Mineralogie,K?ln,Germany;2.Laboratory of Palaeobotany and Palynology, Institute of Environmental Biology,Universiteit Utrecht,Utrecht,The Netherlands;3.Geoforschungszentrum Potsdam,Potsdam,Germany;4.Department of Geography,University of Hull,Hull,UK;5.Institut für Umweltgeologie,TU Braunschweig,Braunschweig,Germany;6.CIRISIVU, c/o Dipartimento Geomineralogico,Bari,Italy;7.Institut für Seenforschung, LUBW,Langenargen,Germany;8.Dipartimento di Scienze della Terra,University of Pisa,Pisa,Italy |
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Abstract: | Lake Ohrid is considered to be of Pliocene origin and is the oldest extant lake in Europe. A 1,075-cm-long sediment core was
recovered from the southeastern part of the lake, from a water depth of 105 m. The core was investigated using geophysical,
granulometric, biogeochemical, diatom, ostracod, and pollen analyses. Tephrochronology and AMS radiocarbon dating of plant
macrofossils reveals that the sediment sequence spans the past ca. 39,500 years and features a hiatus between ca. 14,600 and
9,400 cal. year BP. The Pleistocene sequence indicates relatively stable and cold conditions, with steppe vegetation in the
catchment, at least partial winter ice-cover of the lake, and oxygenated bottom waters at the coring site. The Holocene sequence
indicates that the catchment vegetation had changed to forest dominated by pine and summer-green oak. Several of the proxies
suggest the impact of abrupt climate oscillations such as the 8.2 or 4.0 ka event. The observed changes, however, cannot be
related clearly to a change in temperature or humidity. Human impact started about 5,000 cal. year BP and increased significantly
during the past 2,400 years. Water column mixing conditions, inflow from subaquatic springs, and human impact are the most
important parameters influencing internal lake processes, notably affecting the composition and characteristics of the sediments. |
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Keywords: | Lake Ohrid Mediterranean Pleistocene Holocene Palaeolimnology |
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