Abstract Lake Balaton, the largest shallow lake in Central Europe, has no natural
outlet, therefore, underwent water level changes during its 15,000–17,000 years of
history. The lake is very sensitive to both climate changes and human impacts. Surroundings
have been inhabited since the Stone Age; however, heavy human impact can be recognized
during the past 6000 years. In this study, we established three different stages for
and reconstructed water level changes of Lake Balaton by geochemical data, subfossil
Cladocera and diatom remains in the sediments of the Zalavári Pond, a part of the
Kis-Balaton wetland. In 9900–8600 cal. year BP, climate was dry, water level was low,
and there was a wetland in this area. Although organic matter content was low in the
sediment, the ratio of Fe/Mn was high. Between 5600 and 5000 cal. year BP, water level
increased, Fe/Mn ratio shows that oxygen conditions of sediments was improved in agreement
with the relatively low number of diatom remains and dense chydorid remains. About
5000 cal. year BP, water level of Lake Balaton decreased as indicated by high organic
content with low carbonate and high Fe/Mn ratio in the sediments (oxygen depletion).
At the bottom of this section, high Fe and S concentrations showed accumulation of
pyrite (FeS2) that is common in wetlands with very low redox potential. Low abundance
of Cladocera remains together with rich and diverse diatom flora confirm the low water
level hypothesis. Our data support that the water level of Lake Balaton was higher
between 8600 and 5000 cal. year BP than it is at present.
