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- ItemMediterranean climate since the Middle Pleistocene: A 640 ka stable isotope record from Lake Ohrid (Albania/Macedonia)(Katlenburg-Lindau : European Geosciences Union, 2015) Lacey, J.H.; Leng, M.J.; Francke, A.; Sloane, H.J.; Milodowski, A.; Vogel, H.; Baumgarten, H.; Wagner, B.Lake Ohrid (Macedonia/Albania) is an ancient lake with a unique biodiversity and a site of global significance for investigating the influence of climate, geological and tectonic events on the generation of endemic populations. Here, we present oxygen (δ18O) and carbon (δ13C) isotope data on carbonate from the upper ca. 248 m of sediment cores recovered as part of the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) project, covering the past 640 ka. Previous studies on short cores from the lake (up to 15 m, < 140 ka) have indicated the Total Inorganic Carbon (TIC) content of sediments to be highly sensitive to climate change over the last glacial-interglacial cycle, comprising abundant endogenic calcite through interglacials and being almost absent in glacials, apart from discrete bands of early diagenetic authigenic siderite. Isotope measurements on endogenic calcite(δ18Oc and δ13Cc) reveal variations both between and within interglacials that suggest the lake has been subject to hydroclimate fluctuations on orbital and millennial timescales. We also measured isotopes on authigenic siderite (δ18Os and δ13Cs) and, with the δ18OCc and δ18Os, reconstruct δ18O of lakewater (δ18Olw) through the 640 ka. Overall, glacials have lower δ18Olw when compared to interglacials, most likely due to cooler summer temperatures, a higher proportion of winter precipitation (snowfall), and a reduced inflow from adjacent Lake Prespa. The isotope stratigraphy suggests Lake Ohrid experienced a period of general stability through Marine Isotope Stage (MIS) 15 to MIS 13, highlighting MIS 14 as a particularly warm glacial, and was isotopically freshest during MIS 9. After MIS 9, the variability between glacial and interglacial δ18Olw is enhanced and the lake became increasingly evaporated through to present day with MIS 5 having the highest average δ18Olw. Our results provide new evidence for long-term climate change in the northern Mediterranean region, which will form the basis to better understand the influence of major environmental events on biological evolution within the lake.
- ItemThe environmental and evolutionary history of Lake Ohrid (FYROM/Albania): interim results from the SCOPSCO deep drilling project(Katlenburg-Lindau : European Geosciences Union, 2017) Wagner, Bernd; Wilke, Thomas; Francke, Alexander; Albrecht, Christian; Baumgarten, Henrike; Bertini, Adele; Combourieu-Nebout, Nathalie; Cvetkoska, Aleksandra; D'Addabbo, Michele; Donders, Timme H.; Föller, Kirstin; Giaccio, Biagio; Grazhdani, Andon; Hauffe, Torsten; Holtvoeth, Jens; Joannin, Sebastien; Jovanovska, Elena; Just, Janna; Kouli, Katerina; Koutsodendris, Andreas; Krastel, Sebastian; Lacey, Jack H.; Leicher, Niklas; Leng, Melanie J.; Levkov, Zlatko; Lindhorst, Katja; Masi, Alessia; Mercuri, Anna M.; Nomade, Sebastien; Nowaczyk, Norbert; Panagiotopoulos, Konstantinos; Peyron, Odile; Reed, Jane M.; Regattieri, Eleonora; Sadori, Laura; Sagnotti, Leonardo; Stelbrink, Björn; Sulpizio, Roberto; Tofilovska, Slavica; Torri, Paola; Vogel, Hendrik; Wagner, Thomas; Wagner-Cremer, Friederike; Wolff, George A.; Wonik, Thomas; Zanchetta, Giovanni; Zhang, Xiaosen S.This study reviews and synthesises existing information generated within the SCOPSCO (Scientific Collaboration on Past Speciation Conditions in Lake Ohrid) deep drilling project. The four main aims of the project are to infer (i) the age and origin of Lake Ohrid (Former Yugoslav Republic of Macedonia/Republic of Albania), (ii) its regional seismotectonic history, (iii) volcanic activity and climate change in the central northern Mediterranean region, and (iv) the influence of major geological events on the evolution of its endemic species. The Ohrid basin formed by transtension during the Miocene, opened during the Pliocene and Pleistocene, and the lake established de novo in the still relatively narrow valley between 1.9 and 1.3 Ma. The lake history is recorded in a 584 m long sediment sequence, which was recovered within the framework of the International Continental Scientific Drilling Program (ICDP) from the central part (DEEP site) of the lake in spring 2013. To date, 54 tephra and cryptotephra horizons have been found in the upper 460 m of this sequence. Tephrochronology and tuning biogeochemical proxy data to orbital parameters revealed that the upper 247.8 m represent the last 637 kyr. The multi-proxy data set covering these 637 kyr indicates long-term variability. Some proxies show a change from generally cooler and wetter to drier and warmer glacial and interglacial periods around 300 ka. Short-term environmental change caused, for example, by tephra deposition or the climatic impact of millennial-scale Dansgaard-Oeschger and Heinrich events are superimposed on the long-term trends. Evolutionary studies on the extant fauna indicate that Lake Ohrid was not a refugial area for regional freshwater animals. This differs from the surrounding catchment, where the mountainous setting with relatively high water availability provided a refuge for temperate and montane trees during the relatively cold and dry glacial periods. Although Lake Ohrid experienced significant environmental change over the last 637 kyr, preliminary molecular data from extant microgastropod species do not indicate significant changes in diversification rate during this period. The reasons for this constant rate remain largely unknown, but a possible lack of environmentally induced extinction events in Lake Ohrid and/or the high resilience of the ecosystems may have played a role. © Author(s) 2017.