Evolutionary, geological and environmental history of ancient Lake Ohrid (Albania and Macedonia)

Background

Transboundary Lake Ohrid between Albania and Macedonia is considered to be the oldest continuously existing lake in Europe with an age of likely three to five million years. Located in a tectonic graben, the lake is amongst the few worldwide lakes existing since the Tertiary. Another peculiarity of Lake Ohrid is its extraordinary high degree of endemism, including more than 210 described endemic species. Taken its size into account, Lake Ohrid has the highest degree of endemism worldwide. Therefore, Lake Ohrid is one of the very few lakes in the world representing a hot spot of evolution and a potential evolutionary reservoir enabling the survival of relict species. The proposed continuous existence since the Tertiary makes Lake Ohrid an excellent archive of long and short term environmental changes in the central northern Mediterranean region. Because of its geographic position and its presumed old age, Lake Ohrid represents an important link between climatic and environmental records from the Mediterranean Sea and the adjacent continents. Furthermore, Lake Ohrid is an ideal target to investigate one of the most debated issues in evolutionary biology - modes and tempo of speciation, i.e., whether biotic evolution is triggered by long-term stability or by rapid changes.

Results

Hydroacoustic and airgun seismic surveys carried out in 2004, 2007, and 2008 revealed that the lacustrine slope areas show very complex structures including heavily faulted areas, numerous slides, and foresets, whereas the central basin is filled with several hundred meters thick undisturbed sedimentary sequences. Within the scope of the ongoing project more than 60 up to ca. 15 m long sedimentary records have been recovered between 2001-2007 from various sites of the lake basin. Some of these records penetrate back into the last glacial and one covers the past glacial/interglacial cycle back to MIS 6. Multidisciplinary investigations on these sediments confirmed that Lake Ohrid sensitively records past climatic and environmental changes in the northern Mediterranean region, as well as volcanic ash dispersal from Italian volcanoes. However, with respect to the extraordinary high endemism in the lake, these records are too short to provide information about the age and origin of the lake and to unravel the mechanisms controlling the evolutionary development. Molecular clock analyses of mitochondrial DNA genes from several endemic species flocks (i.e., groups of closely related species) indicate that Lake Ohrid is probably two to three million years old. Moreover, concurrent genetic brakes in several invertebrate groups indicate that major geological and/or environmental events are likely to have shaped the evolutionary history of endemic faunal elements in Lake Ohrid.


Perspectives

In order to
(1) better understand the impact of major geological/environmental events on general evolutionary processes and on generating an extraordinary degree of endemic biodiversity,
(2) obtain a continuous record containing information on climate changes and tectonic and volcanic activities in the central northern Mediterranean region, and
(3) obtain more precise information about the age, origin, and evolution and of the lake,
a deep-drilling in Lake Ohrid within the scope of the International Continental Scientific Drilling Program (ICDP) is aspired. A workshop to form a competitive international research team and to develop a full drilling proposal took place in the city of Ohrid, Republic of Macedonia, from October 13 - 17, 2008.

Projekt Webseite

www.ohrid-drilling.org

Main collaboration partners

T. Wilke, C. Albrecht
Univ. Giessen, DE

S. Krastel, K. Lindhorst
The Future Ocean
IFM-GEOMAR, DE

K. Reicherter
RWTH Aachen, DE

S. Trajanovski, G. Kostoski
Hydrobiological Institute Ohrid, MK

A. Grazhdani, M. Sanxhaku, E. Adhami
Univ. Politeknik Tirana, AL

G. Zanchetta, R. Sulpizio
Univ. di Pisa, IT

F. Anselmetti
Eawag, Switzerland

J. Holtvoeth, G. Wolff
Univ. of Liverpool, UK

M. Leng
NERC, UK

A. F. Lotter
Univ. Utrecht, NL

J. Reed
Univ. of Hull, UK

P. Rosén
CIRC/Umeå Univ., SE

S. Schouten, E. Hopmans
NIOZ, NL

A. Schwalb
TU Braunschweig, DE

T. Schwenk
Univ. of Bremen, DE

Funded by