Climate change impact on thermal and oxygen regime of shallow lakes

摘要

Among the numerous processes that govern the functioning of a lake ecosystem, the regime of dissolvedoxygen (DO) is of primary importance. The DO content is strongly affected by the temperature regime, mixingconditions and by the duration of the ice-covered period. These are formed due to atmospheric forcing and are,therefore, subject to variations in regional climate. Despite the large amount of data revealing the physicaleffect on the biological and chemical regimes in lakes, there is still insufficient understanding, both qualitativeand quantitative, of how a lake ecosystem would be affected by changes in the lake temperature and mixingconditions due to changes in the atmospheric forcing. Below, the study of shallow lakes’ response to climaticchanges using the coupled FLakeFLakeEco modelling system is presented. The results obtained reveal theextreme vulnerability of the lakes’ ecosystems to changes in atmospheric forcing. In ‘future’ climate thepermanent existence of potentially dangerous anaerobic zones in shallow lakes is expected. The projecteddecreased oxygen concentrations are caused by: (1) the reduced oxygen flux from the atmosphere to the lakesdue to increased temperature; and (2) strengthened density stratification of the water columns which wouldprevent aeration of the near-bottom layers.