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T9
Holocene palaeoclimate reconstruction in the Eastern Mediterranean: a quantitative
diatom study of an approximately 18 m long sediment core from Lake Kinneret
(Israel)
H. Vossel 1 *, T. Litt 2 and J. Reed 3
1, 2 Rheinische Friedrich-Wilhelms-University Bonn, Steinmann-Institute for Geology, Mineralogy and
Palaeontology, Bonn, Germany
3 University of Hull, Department of Geography, Environment and Earth Sciences, Hull, United Kingdom
This study comprises a relatively low resolution study of an 18 m core by analysis of 19
sediment samples for preliminary investigation of remarkable shifts in the diatom flora of
Lake Kinneret over the last ca. 8,000 years. The aim is to clarify why diatom assemblages
have changed over time, and to establish whether the results are in accord with (1)
previous inference based on proxies such as pollen and (2) output from the climatological
models of the Levant region.
All samples were prepared using standard techniques by Battarbee (1986). The wet
sediment samples were firstly treated with H 2 O 2 to remove and oxidize all organic
components and in a second step with HCl to remove the carbonate material. Microscope
slides with two different concentrations were prepared by using Naphrax as mountant. 500
diatom valves per slide were counted on a Leica light microscope, and were identified
using standard texts and a special Atlas of freshwater diatoms in Israel.
The lake is freshwater throughout, with open hydrology, but highly alkaline. 98 % of the
diatom taxa can be classified as oligohalobous-indifferent, and as alkaliphilous. Five main
diatom assemblage zones can be recognised using CONISS-analysis afterwards.
Changes in the diatom assemblages over the last ca. 8,000 years can be interpreted
mainly in terms of productivity shifts, from an oligotrophic flora at the base to
hypereutrophic in the modern lake. The trend towards eutrophication accelerates after
3,000 cal. yrs. BP, indicating the influence of increased human activity in the catchment.
The pollen record also shows an increase in human activity around Lake Kinneret during
that time (Schiebel, 2013).
There is also some evidence for lake-level fluctuations. Low lake-level stands are
characterized by a low diatom concentration and the increasing occurrence of littoral taxa.
High lake level stands are marked by the occurrence of planktonic species, such as
Cyclotella ocellata, in huge numbers and high diatom concentrations. The inferred lakelevel
oscillations appear to correlate well with output from the climatic models from the
Levant region, representing fluctuations in moisture availability (Litt et al., 2012). The
results can also be correlated with previous diatom studies from short core material of the
littoral zones of Lake Kinneret, which cover the last 3,000 years cal BP (Pollingher &
Ehrlich, 1984; Ehrlich, 1985).
Keywords: diatoms; Lake Kinneret; Holocene; eutrophication; lake-level fluctuations
Battarbee, R. W., 1986. Diatom analysis. In: Berglund BE (ed.) Handbook of Holocene palaeoecology and
palaeohydrology. Wiley, Chichester, pp. 527-670.
Ehrlich, A., 1985. The eco-biostratigraphic significance of the fossil diatoms of Lake Kinneret. GSI Current
Research 5: 24-30.
Litt, T., C. Ohlwein, F.H. Neumann, A. Hense & M. Stein, 2012. Holocene climate variability in the Levant from
the Dead Sea pollen record. Quaternary Science Review 49: 95-105.
Pollingher, U. & A. Ehrlich, 1984. The planktonic diatoms of Lake Kinneret, Israel, during the last 5000 years –
their contribution to the algal biomass. Proc. 8th Int. Symp. Living and Fossil Diatoms, Paris, 27-30 Aug. 1984.
Schiebel, V., 2013. Vegetation and climate history of the southern Levant during the last 30,000 years based
on palynological investigation. Unpublished Phd thesis.