is a

caldera lake A volcanic crater lake is a lake in a crater that was formed by explosive activity or a collapse during a volcanic eruption. Formation Lakes in calderas fill large craters formed by the collapse of a volcano during an eruption. Lakes in maars ...

located south of

Kagoshima , is the capital Cities of Japan, city of Kagoshima Prefecture, Japan. , the city had an estimated population of 583,966 in 285,992 households, and a population density of 1100 persons per km2. The total area of the city is . Etymology While the ...

city;

Kyūshū is the third-largest island of Japan's four main islands and the most southerly of the four largest islands (i.e. excluding Okinawa and the other Ryukyu (''Nansei'') Islands). In the past, it has been known as , and . The historical regio ...

island,

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

. It is perhaps best known to tourists as the location of the purported sightings of a monster named Issie, and as the largest lake on Kyūshū island with a surface area of and a shoreline length of .

Deterioration

The development of the areas surrounding Lake Ikeda has caused the quality of the water to decline since 1955. Other causes include an irrigation project, developed for agricultural field and households in the area, which was initiated in 1965, for it the courses of three nearby rivers were diverted into the lake. The irrigation system has been in operation since 1982, resulting in a considerable improvement of the water quality although since the 1950s the transparency of the lake, though still ranked No. 7 in the world, has decreased from to approximately .

Animals

Lake Ikeda is known to harbour large

eel Eels are ray-finned fish belonging to the order Anguilliformes (), which consists of eight suborders, 20 families, 164 genera, and about 1000 species. Eels undergo considerable development from the early larval stage to the eventual adult stage ...

s, some six feet in length. In 1998, a benthological survey was conducted in the lake, which found that there were no

zoobenthos Benthos (), also known as benthon, is the community of organisms that live on, in, or near the bottom of a sea, river, lake, or stream, also known as the benthic zone.oligochaetes Oligochaeta () is a subclass of soft-bodied animals in the phylum Annelida, which is made up of many types of aquatic and terrestrial worms, including all of the various earthworms. Specifically, oligochaetes comprise the terrestrial megadril ...

and a

chironomid Chironomidae , commonly known as non-biting midges or chironomids , are a family of Nematoceran flies with a global distribution. They are closely related to the families Ceratopogonidae, Simuliidae, and Thaumaleidae. Although many chironomid s ...

were found. The lake was already considered

oligotroph An oligotroph is an organism that can live in an environment that offers very low levels of nutrients. They may be contrasted with copiotrophs, which prefer nutritionally rich environments. Oligotrophs are characterized by slow growth, low rates o ...

ic until the 1940s, but one theory for the further drop in underwater life is that the existing life in Lake Ikeda has been affected by

global warming Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...

Geology

It is within the Ikeda Caldera and surrounded by its rim and associated volcanic domes.

Mythology

Lake Ikeda is important in the local

Shinto , also called Shintoism, is a religion originating in Japan. Classified as an East Asian religions, East Asian religion by Religious studies, scholars of religion, it is often regarded by its practitioners as Japan's indigenous religion and as ...

folklore of the surrounding regions. Local religious tradition originally held the lake as the origin of humankind.

Issie

is a Japanese lake monster said to lurk in Lake Ikeda. It is described as being

saurian Sauria is the clade of diapsids containing the most recent common ancestor of Archosauria (which includes crocodilians and birds) and Lepidosauria (which includes squamates and the tuatara), and all its descendants. Since most molecular phyl ...

in appearance. The naming convention is analogous to "Nessie" (the

Loch Ness Monster The Loch Ness Monster (), known affectionately as Nessie, is a mythical creature in Scottish folklore that is said to inhabit Loch Ness in the Scottish Highlands. It is often described as large, long-necked, and with one or more humps protrud ...

). According to mythology, Issie was a white mare who lived together with her foal on the shore of Lake Ikeda. However, when the foal was kidnapped by a

samurai The samurai () were members of the warrior class in Japan. They were originally provincial warriors who came from wealthy landowning families who could afford to train their men to be mounted archers. In the 8th century AD, the imperial court d ...

and Issie was unable to find it, she jumped into the lake and her despair transformed her into a giant, saurian beast, which since then frequently surfaces, trying to find her lost child.''

Metropolis A metropolis () is a large city or conurbation which is a significant economic, political, and cultural area for a country or region, and an important hub for regional or international connections, commerce, and communications. A big city b ...

'', "Fortean Japan", 27 June 2008, p. 12. The creature was reportedly photographed in 1978 by a man who went by the name "Mr. Matsubara". Twenty other people reportedly also saw the creature swimming in the lake in 1978; they described it as black and having two humps, each about 5 meters (16 feet) long.

References

External links

Ikeda and Yamagawa: National catalogue of the active volcanoes in Japan
- Japan Meteorological Agency

- Geological Survey of Japan {{Lakes of Japan Ikeda Ikeda Ibusuki, Kagoshima