Vesijärvi

Vesijärvi
Vesijärvi at night.
Location	Päijänne Tavastia
Coordinates	61°04′58″N 25°32′18″E / 61.08278°N 25.53833°E / 61.08278; 25.53833Coordinates: 61°04′58″N 25°32′18″E / 61.08278°N 25.53833°E / 61.08278; 25.53833
Catchment area	Enonselkä Basin
Basin countries	Finland
Max. length	25 km
Surface area	107.57 km²[1]
Average depth	6 m
Max. depth	42 m
Water volume	484 km³
Shore length1	181 km
Surface elevation	81.4 m[1]
Settlements	Asikkala, Lahti
References	[1]
1 Shore length is not a well-defined measure.

Vesijärvi is a lake of 111 km² in the Enonselkä Basin of Lahti in southern Finland. It suffered severe effects of eutrophication in the 1960s and a restoration programme began in the 1970s.

The name of the lake means The Water Lake.

Cyanobacteria Bloom Remediation

• Biomanipulation is an approach that applies the top-down model of community organization to alter ecosystem characteristics.
• Ecologists used this model to remediate the lake's eutrophication. In this case, manipulation—and introduction—of higher-level consumers reduced cyanobacteria blooms as an alternative to using chemical treatments.
• Lake Vesijärvi was polluted by city sewage and industrial wastewater until 1976, at which point pollution controls reduced these inputs. By 1986 massive blooms of cyanobacteria began occurring, as well as dense populations of roach, a fish that benefited from the pollution's mineral nutrients. Roach eat zooplankton that otherwise keep cyanobacteria in check. To remediate this problem, ecologists removed about a million of kilograms of fish—reducing roach to 20% of their former abundance—between 1989 and 1994, and stocked the lake with pike perch which eats roach. The water has since become clear, and the last cyanobacteria bloom was in 1989. ^[2]

See also

• Enonsaari - an island located in the lake.

References

Location in Finland (yellow dot)

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