Lakes in temperate ecoregions - overview
The pristine status
Most lakes in temperate regions are dimictic, with two periods of stratification in summer and winter, although there are exceptions such as the Lake Constance, which lacks winter stratification. Depending on origin, depth, altitude, catchment size and geology there is a multitude of lake types with characteristic biota. Primary production of most shallow lakes is dominated by macrophytes, while phytoplankton is the main primary producer in most deep lakes.
Eutrophication has been the main human impact for several decades, leading to algal blooms, oxygen depletion in the deep zones and fish kills. Though many of the extreme cases have been restored, the majority of lakes are still suffering from eutrophication, as well as from shoreline modification.
Climate change impact
Climate change might have profound effects on the nitrogen (N) dynamics in the cultivated landscape as well as on N transport in streams and the eutrophication of lakes. N loading from land to streams is expected to increase in North European temperate lakes due to higher winter rainfall and changes in cropping patterns. This could lead to loss of submerged macrophytes and changes in the structure of zooplankton and fish communities that enhance the risk of lake shifts from a clear to a turbid in a warmer North European temperate climate.
For further reading
- Jeppesen E, Kronvang B, Olesen JE, et al. (2010) Climate change effects on nitrogen loading from cultivated catchments in Europe: implications for nitrogen retention, ecological state of lakes and adaptation. Hydrobiologia, 663, 1–21.
link to article
- Jeppesen E, Mehner T, Winfield IJ, et al. (2012) Impacts of climate warming on the long-term dynamics of key fish species in 24 European lakes. Hydrobiologia, 694, 1–39.
link to article