Saline lakes of the Seewinkel
Saline lakes are rare in the European inland. They can only be found in Seewinkel and in central Hungary. Very big waters can be found in other parts of the world e.g. in Kazakhstan, Mongolia, Australia and the Etosha pan. But also from the global point of view, these regions are rare. It is one of the main tasks to preserve these unique landscapes. There are about 45 saline lakes between the Neusiedler See and the Hanság that characterise like no other landscape component the Seewinkel area.
Where do theses shallow saline waters come from?
The creation of the saline lakes along the east shore of the Neusiedler See (Stinkerseen, Illmitzer Zicklacke...) is not completely explored yet, but it might be linked to the formation of the lake embankment. Sediments from the bottom of the lake were deposited by water currents and ice movement. A breech in the embankment led to erosion of an inland depression. This is where the saline lakes could form.
The saline lakes of the central Seewinkel (Lange Lacke, Wörthenlacken...) are even older than the Neusiedler See itself: According to the accepted Riedl-theory, so called pingos formed during the Würm ice-age (115.000 to 10.000 years ago). Pingos prevented the Danube from depositing it's sediments there. When the pingos melted, the shallow basins filled with water.
About 13 million years ago, the area was part of the open sea. Huge formations of sediment forced the sea to retreat to the east. According to Husz a soda-carrying soil horizon developed during the last interglacial period with arid climate conditions. The groundwater rose and salt reached the surface by capillary action. The regular desiccation helps to maintain the saline lakes. The bottom of the saline lake is impermeable. If the groundwater reaches this layer from below, salt rises by capillary action into the system of the saline lake. If the groundwater level declines, the salt concentration decreases and the lake desalinates and could even disappear. The saline lakes differ from each other in their chemical composition and soil substratum - that is why it is so important to preserve each and every saline lake.
Between the extremes
The water level varies with the seasons, from high water levels in springtime to desiccation in summer. Precipitation and evaporation play the key role. The salt concentration of the saline lakes increases, when the water level drops. The "soda snow" consists of sodium carbonate (Na2CO3) but there can also be Glauber salt (Na2SO4), Epsom salt (MgSO4) and common salt (NaCl).
Saline lakes are extreme habitats not only because of their salinity and the changing water level but also because of extreme variations in night and day temperatures. Before total desiccation, temperatures can range from 18 to 38°C.
Over the course of a year, the water level can vary in depth between 70 cm and total desiccation. Precipitation in autumn and winter compensate the heavy evaporation in summer. Once there were more than 100 saline lakes in this area, but most have been lost due to human interference, some silted in naturally.
The flora of the Seewinkel is unique. Plants that can tolerate saline conditions (halophytes) have a clear advantage. That is why along the shore of the lakes there are plants whose next of kin grow at seashores. Lepidium cartilagineum, Tripolium pannonicum, Saltwort and Sea Purslane can be found here.
The increasing reed belt at a saline lake can be a sign for natural desalinisation. If the salt concentration drops, the clear advantage of the halophytes disappears. "Normal" plants immigrate; a layer of humus forms and the saline lakes disappear.
Typical inhabitants of the area are the Avocet and the Kentish Plover that only nest in this part of Austria. Many species of birds search for food in the shallow waters and at the shores. Redshanks, Black-tailed Godwits and Lapwings nest here. Other birds, like the Ruff, the Dunlin, the Curlew sandpiper and the Great ringed Plover rest here during their migration. Seagulls, terns and herons rest here as well. Depending on the water level, the saline lakes attract different kinds of ducks and geese. When the water level is high, Black-necked and Little Grebes build their nests here.