Lake Hévíz

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lake_name = Lake Hévíz
image_lake = Heviz_to_magyar.jpg
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location = Hévíz
coords = coord|46|47|14|N|17|11|35|E|type:waterbody_region:HU|display=inline,title
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basin_countries = Hungary
length =
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area = 47,500 m²
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residence_time = 28 hours
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Lake Hévíz is located close to Hévíz, Hungary, near the western end of Lake Balaton, five miles from Keszthely.

It is the largest thermal lake in Europe (47,500 square metres in area). The flow of water is very strong and the lake is believed to be completely replenished each day.

The waters are reputed to have curative effects, and there is a thriving health tourism industry in the area.

Microscopic organisms of the lake

The fauna and flora are unique in Lake Hévíz due to the temperature and chemical composition of the water, which is slightly radioactive and contains reduced sulfuric compounds as well as oxygen in solution. Several species so far can be found only in this lake.

Bacteria is the dominant life form in the lake; it is possible that this is a cause of the curative effect. Several taxons can be found here. Most common Cyanobacteria are filamentous blue-green algae ("Oscillatoria princeps", "O. tenuis", "O. jasoruensis", "O. chlorina", "Spirulina major"). It is interesting to note that half of the blue species are thermophile, stenoterm ones. There are two thermophile blue green alga species ("Pseudanabaena papillaterminata", "Pseudanabaena crassa") of which Lake Hévíz is the only Hungarian habitat.

Bacterial tektons are typical of the lake. The crater is covered mostly by "Thiothrix" sp. and "Beggiatoa" sp. from a depth of 1.5 m to the opening of the springcave. These together with the bacterium species play an important role in the lake's sulfur cycle.

Actinomycetes ("Streptomyces" sp., "Micromonospora" sp.) are also worth mentioning. "Micromonospora heviziensis" for instance, a very powerful protein and cellulose decomposer, can only be found here in the world. Microbispora amethystogenes on the other hand, which accumulates iodine in its cells, is to be found in only few lakes in the world. Unfortunately this latter species has not been found in the lake since 1980s as a result of excessive mining.Changing environment affected other bacteria as well. "Micromonospora carbonacea" and "M. chalcea" was not detected in the 1990s. Actinomycetes communities have become dominated by "Micromonospora purpureochromogenes", while "M. heviziensis" was suppressed. Antibiotics secreting "Streptomyces" are likely to be found.
Green algae – especially "Chlorella" sp. – are present all over the lake except for the springcave and its surroundings. "Navicula cryptocephala" and "Navicula capitatoradiata "are common diatoms in the lake. The biodiversity of the phytoplankton is poor and its biomass is low, thus the lake's trophic level ranges from oligotrophic to mesotrophic.

There are two new species of Nematoda: "Crocodolrylaimus thermalis" and "Neoactinolaimus tepidus". There can be found real rarities among Rotatorias as well ("Epiphanes brachionus" var. "Spinosus", "Lecane inermis"), which are only present in warm waters. Jenő Ponyi has described the lake's primitive crustaceans in detail. Also a unique "Hydracarina acarus" is said to have found its habitat outside the fence surrounding the lake.

See also

* Hévíz Spa