Lake Akan 阿寒湖
The view from Mount Oakan (July 2008)
Location	Kushiro, Hokkaidō, Japan
Coordinates	43°27′6″N 144°5′55″E / 43.45167°N 144.09861°E / 43.45167; 144.09861Coordinates: 43°27′6″N 144°5′55″E / 43.45167°N 144.09861°E / 43.45167; 144.09861
Lake type	Dimictic
Primary outflows	Akan River
Catchment area	148 km2 (57 sq mi)
Basin countries	Japan
Surface area	13 km2 (3,200 acres)
Average depth	17.8 m (58 ft)
Max. depth	44.8 m (147 ft)
Water volume	0.23 km3 (0.055 cu mi)
Shore length1	25.9 km (16.1 mi)
Surface elevation	420 m (1,400 ft)
Frozen	December to April
Islands	4: Ōjima, Kojima, Yaitai Island, Chūrui Island
Settlements	Kushiro
1 Shore length is not a well-defined measure.

Lake Akan (阿寒湖, Akan-ko^?) is a lake in Kushiro, Hokkaidō, Japan. It is located in Akan National Park.^[1]

[edit] History

Volcanic activity formed the lake some 6,000 years ago, when a dam 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. ^[2]

[edit] Flora and fauna

The lake is famous for the marimo (Aegagropila sauteri), aggregations of algae that form into spherical shapes 2–15 cm in diameter. Other flora of the lake include the following:^[2]

• Phragmites communis
• Nuphar sp.
• Potamogeton crispus
• Hydrilla verticillata
• Myriophyllum verticillatum
• Vallisneria gigantea
• Melosira italica
• Asterionella formosa
• Synedra

Kokanee salmon (Oncorhynchus nerka) are native to Lake Akan. Other fauna of the lake include the following:^[2]

• Zooplankton:
  • Daphnia longiremis
  • Bosmina coregoni
  • Eurytemora affinis
• Bottom:
  • Chironomus plumosus
  • Tubificidae
• Fish:
  • Cyprinus carpio
  • Carassius
  • Hypomesus olidus
  • Leuciscus hakonensis

[edit] References