PP11D-07
Integrated perspectives on geological and biological dynamics in ancient Lake Ohrid

Monday, 14 December 2015: 09:30
2012 (Moscone West)
Bernd Wagner1, Thomas Wilke2, Alexander Francke1, Niklas Leicher1, Sebastian Krastel3, Giovanni Zanchetta4, Roberto Sulpizio4, Laura Sadori5, Janna Just1, Zlatko Levkov6, Thomas Wonik7, Hendrik Vogel8 and Friederike Wagner-Cremer9, (1)University of Cologne, Cologne, Germany, (2)Justus-Leibig University Gießen, Department of Animal Ecology & Systematics, Gießen, Germany, (3)Inst fuer Geowissenschaften, Kiel, Germany, (4)University of Pisa, Dipartimento di Scienze della Terra, Pisa, Italy, (5)Università degli studi di Roma “La Sapienza”, Dipartimento di Scienze Ambientali, Roma, Italy, (6)University of Skopje, Skopje, Macedonia, (7)Leibniz Institute for Applied Geophysics, Hannover, Germany, (8)University of Bern, Bern, Switzerland, (9)Utrecht University, Utrecht, Netherlands
Abstract:
Lake Ohrid on the Balkan Peninsula is, along with lakes Baikal and Elgygytgyn in Russia and Lake Bosumtwi in Ghana, one of the very few lakes in the world that provides a continuous and high resolution record of environmental change of >1 Ma. With >300 endemic taxa, Lake Ohrid has the fourth highest degree of endemism in the world, being exceeded only by lakes Baikal, Tanganyika and Malawi. The combination of its long existence and high endemism makes Lake Ohrid a unique target to study the drivers of speciation and endemism. For this purpose, a 569 m long sediment sequence was recovered from the central part of the lake in spring 2013 within the scope of the International Continental Scientific Drilling Program (ICDP) and the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) project.

Here, we present the results to date of analysis of the upper 248 m of this sequence, which covers the last ca. 640 ka according to an age model based on tephrostratigraphy as well as tuning of in situ physical and biogeochemical proxy data to orbital parameters and to the global benthic isotope stack. The sedimentological, physical, and geochemical data from the sediment sequence indicate changes in primary productivity, water column stratification, and water depth of the lake, and in weathering and erosion processes in the catchment. These changes can be clearly correlated with the intensity of glacial and interglacial periods as well as stadials and interstadials. However, paleontological and molecular clock analyses indicate that these changes and also the tephra deposition from eruptions of Italian volcanoes apparently did not lead to significant extinction events in the endemic species community. The lack of such catastrophic extinction events is probably due to the buffering capacity of the deep lake, possibly enhanced by the continuous existence of subaquatic karst springs with relatively stable habitats in the surroundings. This would enable the survival of species over time and the unusual stability of Lake Ohrid is regarded as one of the main drivers for the high endemism in the lake.

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