Lake Hévíz is located in

Hévíz Hévíz () is a spa town in Zala County, Hungary, about from the city of Keszthely. Description of the lake The town is located near Lake Hévíz, the world's second-largest thermal lake, but biologically the biggest active natural lake. ...

Hungary Hungary is a landlocked country in Central Europe. Spanning much of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and ...

, near the western end of

Lake Balaton Lake Balaton () is a freshwater rift lake in the Transdanubian region of Hungary. It is the List of largest lakes of Europe, largest lake in Central Europe, and one of the region's foremost tourist destinations. The Zala River provides the larges ...

, from

Keszthely Keszthely (; also known by alternative names) is a Hungarian city of 20,895 inhabitants located on the western shore of Lake Balaton. It is the second largest city by the lake and one of the more important cultural, educational and economic hub ...

. It is the largest swimmable thermal lake in the world ( in area), and is the second largest thermal lake in general, second to only the

Frying Pan Lake Frying Pan Lake (renamed Waimangu Cauldron in 1963 though not widely used) is the world's largest hot spring. It is located in the Echo Crater of the Waimangu Volcanic Rift Valley, New Zealand and its acidic water maintains a temperature of about ...

in New Zealand, which is too hot for swimming. The flow of water is very strong and the water in the lake is completely replenished every 72 hours. Its minimum depth is 2 meters, reaching a maximum depth of 38 meters, exactly at the point where the hot thermal water comes out to the surface.

Microscopic organisms of the lake

The

fauna Fauna (: faunae or faunas) is all of the animal life present in a particular region or time. The corresponding terms for plants and fungi are ''flora'' and '' funga'', respectively. Flora, fauna, funga and other forms of life are collectively ...

and

flora Flora (: floras or florae) is all the plant life present in a particular region or time, generally the naturally occurring (indigenous (ecology), indigenous) native plant, native plants. The corresponding term for animals is ''fauna'', and for f ...

are unique in Lake Hévíz due to the

temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

and chemical composition of the water, which contains carbonic acid, calcium, magnesium, hydrogen carbonate, reduced

sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...

ic compounds as well as

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

in solution. Several

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

so far can be found only in this lake.

Bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

is the dominant life form in the lake; it is possible that this is a cause of the curative effect. Several

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

can be found here. Most common

Cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...

are filamentous blue-green algae (''Oscillatoria princeps'', ''O. tenuis'', ''O. jasoruensis'', ''O. chlorina'', '' Spirulina major''). Half of the blue species are

thermophile A thermophile is a type of extremophile that thrives at relatively high temperatures, between . Many thermophiles are archaea, though some of them are bacteria and fungi. Thermophilic eubacteria are suggested to have been among the earliest bacte ...

, 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 Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...

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 the 1980s as a result of excessive

mining Mining is the Resource extraction, extraction of valuable geological materials and minerals from the surface of the Earth. Mining is required to obtain most materials that cannot be grown through agriculture, agricultural processes, or feasib ...

. 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 The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...

– especially ''

Chlorella ''Chlorella'' is a genus of about thirteen species of single- celled or colonial green algae of the division Chlorophyta. The cells are spherical in shape, about 2 to 10 μm in diameter, and are without flagella. Their chloroplasts contain t ...

'' sp. – are present all over the lake except for the springcave and its surroundings. ''

Navicula ''Navicula'' is a genus of boat-shaped diatom (single-celled photosynthetic organisms), comprising over 1,200 species, though many ''Navicula'' species likely do not belong in the genus strictly speaking. ''Navicula'' is Latin for "small ship", ...

cryptocephala'' and ''

capitatoradiata ''are common diatoms in the lake. The biodiversity of the

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater Aquatic ecosystem, ecosystems. The name comes from the Greek language, Greek words (), meaning 'plant', and (), mea ...

is poor and its

biomass Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how ...

is low, thus the lake's

trophic level The trophic level of an organism is the position it occupies in a food web. Within a food web, a food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the ...

ranges from oligotrophic to mesotrophic. There are two new species of

Nematoda The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitism, parasitic. Parasitic ...

: '' 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

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s in detail. Also a unique '' Hydracarina acarus'' is said to have found its habitat outside the fence surrounding the lake.

Medicinal properties

The waters are reported to be beneficial to patients with rheumatic diseases and locomotor disorders, among others. There is a thriving health tourism industry in the area.

References

External links

nature conservation areas of Balaton Uplands National Park

Heviz

{{DEFAULTSORT:Lake Heviz Heviz Geography of Zala County Hot springs of Hungary Heviz Tourist attractions in Zala County Volcanoes of Hungary

Microscopic organisms of the lake

Medicinal properties

See also

References

External links