Wigry Lake: The Cradle of Polish Hydrobiology – A Century of Limnological Exploration

Abstract

Wigry Lake, located in North-Eastern (NE) Poland, has a century-old history of limnological exploration and is an excellent place to assess the impact of catchment changes caused by urbanization on the functioning of a large, polymictic, and flow-through lake. The history of prewar limnological research, the course of hydrochemical effects of urbanization in the river flowing into the lake since the 1970s, and long-term changes in the functioning of Wigry Lake are presented. The collected archival and current results indicate that the hydrochemical type of the lake’s waters remained the same, and the inflow of river waters from the urban catchment strongly transformed the lake bay receiving the load. In the remaining part of the lake, the eutrophication load caused smaller changes because of a gradual reduction in the inflow of nutrients. Consequently, there was an increase in vertical differentiation of oxygen, algal biomass, and their structure. A significant share of supplying the lake with groundwater and the natural in-lake system of biotic and chemical regulations significantly reduced the effects of the eutrophication process. The existing lake biodiversity has been maintained, constituting a valuable element of the European NATURA 2000 system.