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is a lake in
Kushiro
is a city in Kushiro Subprefecture on the island of Hokkaido, Japan. It serves as the subprefecture's capital and it is the most populated city in the eastern part of the island.
Geography
Mountains
* Mount Oakan
* Mount Meakan
* Mount Akan ...
, Hokkaidō
is Japan's second largest island and comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu; the two islands are connected by the undersea railway Seikan Tunnel.
The la ...
, Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
. It is located in Akan National Park
is a national park located on the island of Hokkaidō, Japan. Along with Daisetsuzan National Park, these are the two oldest national parks in Hokkaidō. The park was established December 4, 1934.
Akan is an area of volcanic craters and for ...
and is a Ramsar Site
A Ramsar site is a wetland site designated to be of international importance under the Ramsar Convention,8 ha (O)
*** Permanent 8 ha (P)
*** Seasonal Intermittent < 8 ha(Ts)
**
History
Volcanic activity formed the lake some 6,000 years ago, when alava dam
A volcanic dam is a type of natural dam produced directly or indirectly by volcanism, which holds or temporarily restricts the flow of surface water in existing streams, like a man-made dam. There are two main types of volcanic dams, those creat ...
was formed. The lake used to have a clarity of 8–9 meters in the 1930s. Pollution from local hotspring resorts has decreased the transparency to 3–4 meters.
Flora and fauna
The lake is famous for themarimo
Marimo (also known as Cladophora ball, moss ball, or lake ball) is a rare growth form of ''Aegagropila linnaei'' (a species of filamentous green algae) in which the algae grow into large green balls with a velvety appearance.
The species can be ...
(''Aegagropila linnaei''), aggregations of algae that form into spherical shapes 2–30 cm in diameter. Other flora of the lake include the following:
*Phragmites communis
''Phragmites australis'', known as the common reed, is a species of plant. It is a broadly distributed wetland grass that can grow up to tall.
Description
''Phragmites australis'' commonly forms extensive stands (known as reed beds), which may ...
*Nuphar
''Nuphar'' is a genus of aquatic plants in the family Nymphaeaceae, with a temperate to subarctic Northern Hemisphere distribution. Common names include water-lily (Eurasian species; shared with many other genera in the same family), pond-lily, a ...
sp.
*Potamogeton crispus
''Potamogeton crispus'', the crisp-leaved pondweed, curly pondweed, curly-leaf pondweed or curled pondweed, is a species of aquatic plant (hydrophyte) native to Eurasia but an introduced species and often a noxious weed in North America.
Descr ...
*Hydrilla verticillata
''Hydrilla'' (waterthyme) is a genus of aquatic plant, usually treated as containing just one species, ''Hydrilla verticillata'', though some botanists divide it into several species. It is native to the cool and warm waters of the Old World in ...
*Myriophyllum verticillatum
''Myriophyllum verticillatum'', the whorl-leaf watermilfoil or whorled water-milfoil, is a native to much of North America, North Africa, and Eurasia. It closely resembles another native milfoil, called northern water milfoil (''M. sibiricum'' ...
*Vallisneria gigantea
''Vallisneria'' (named in honor of Antonio Vallisneri) is a genus of freshwater aquatic plant, commonly called eelgrass, tape grass or vallis. The genus is widely distributed in tropical and subtropical regions of Asia, Africa, Europe, and North ...
* Melosira italica
*Asterionella formosa
''Asterionella formosa'' is a species of diatom belonging to the family Tabellariaceae.
It has cosmopolitan distribution.
References
{{Taxonbar, from=Q49600081
Fragilariophyceae ...
* Synedra
Kokanee salmon
The kokanee salmon (''Oncorhynchus nerka''), also known as the kokanee trout, little redfish, silver trout, kikanning, Kennerly's salmon, Kennerly's trout, or Walla, is the non-anadromous form of the sockeye salmon (meaning that they do not migrat ...
(''Oncorhynchus nerka'') are native to Lake Akan.
Other fauna of the lake include the following:
*Zooplankton:
**Daphnia longiremis
''Daphnia'' is a genus of small planktonic crustaceans, in length. ''Daphnia'' are members of the order Anomopoda, and are one of the several small aquatic crustaceans commonly called water fleas because their saltatory swimming style resemb ...
**Bosmina coregoni
''Bosmina'' is a genus in the order Cladocera, the water fleas. Its members can be distinguished from those of '' Bosminopsis'' (the only other genus in the family Bosminidae) by the separation of the antennae; in ''Bosminopsis'', the antennae a ...
**Eurytemora affinis
''Eurytemora'' is a genus of copepods in the family Temoridae. The World Register of Marine Species
The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of ...
*Bottom:
**Chironomus plumosus
''Chironomus plumosus'', also known as the buzzer midge, is a species of nonbiting midge (Chironomidae) that occurs throughout areas in the Northern Hemisphere.
Description
Adult
Adults are pale green with brown legs and grow to . Males have ...
**Tubificidae
The Naididae (including the former family Tubificidae) are a family of clitellate oligochaete worms like the sludge worm, '' Tubifex tubifex''. They are key components of the benthic communities of many freshwater and marine ecosystems. In fres ...
*Fish:
**Cyprinus carpio
The Eurasian carp or European carp (''Cyprinus carpio''), widely known as the common carp, is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia.Fishbase''Cyprinus carpio'' Linnaeus, 1758/ref>Arkive The ...
**Carassius
''Carassius ''is a genus in the ray-finned fish family Cyprinidae. Most species in this genus are commonly known as crucian carps, though this term often specifically refers to '' C. carassius''. The most well known is the goldfish (''C. auratus ...
**Hypomesus olidus
The pond smelt (''Hypomesus olidus'') is a freshwater species of smelt that inhabits the Arctic
The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, ...
** Leuciscus hakonensis
Climate
See also
*List of Special Places of Scenic Beauty, Special Historic Sites and Special Natural Monuments
To protect Japan's cultural heritage, the country's government selects through the Agency for Cultural Affairs important items and designates them as Cultural Properties under the Law for the Protection of Cultural Properties. Designated items are ...
*Ramsar sites in Japan
The Ramsar Convention on Wetlands of International Importance Especially as Waterfowl Habitat is an international treaty for the conservation and sustainable use of wetlands. Adopted in 1971, it entered into force in 1975 and as of April 2022 ha ...
References
{{DEFAULTSORT:Akan Lakes of Hokkaido Ramsar sites in Japan Volcanic crater lakes Volcanoes of Hokkaido Calderas of Hokkaido VEI-7 volcanoes Lava dammed lakes