Lake Akan


Lake Akan is a lake in Kushiro, Hokkaidō, Japan. It is located in Akan National Park and is a Ramsar Site.

History

Volcanic activity formed the lake some 6,000 years ago, when a lava 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.

Flora and fauna

The lake is famous for its marimo, aggregations of algae that form into spherical shapes 2–30 cm in diameter. Other flora of the lake include the following:
  • Phragmites communis
  • Nuphar sp.
  • Potamogeton crispus
  • Hydrilla verticillata
  • Myriophyllum verticillatum
  • Vallisneria gigantea
  • Melosira italica
  • Asterionella formosa
  • Synedra
Kokanee salmon are native to Lake Akan.
Other fauna of the lake include the following:
  • Zooplankton:
  • *Daphnia longiremis
  • *Bosmina coregoni
  • *Eurytemora affinis
  • Bottom:
  • *Chironomus plumosus
  • *Tubificidae
  • Fish:
  • *Common carp
  • *Crucian carp
  • *Pond smelt
  • *Big-scaled redfin

    Climate