Lake Restoration and Management in a Changing Climate
Lakes across the world are increasingly impacted by human activities, which can cause ‘cocktails’ of multiple stressors to affect their ecological health and status. Nutrient pollution and rising water temperatures are causing eutrophic blooms of toxic cyanobacteria in many shallow lakes, whilst abstraction pressures for drinking and irrigation is lowering water levels (or even drying out) on others.
As a result, there is a growing need for effective lake conservation and restoration strategies that help mitigate the effects of an increasingly pressurised world. A new open-access special issue of the journal Water compiled by MARS scientist Erik Jeppesen and colleagues brings together a set of papers on this theme. The research profiled in the special issue is largely focused on the restoration of eutrophic lakes under climate change, and has been undertaken by scientists across the world.
A key theme running the studies is how nutrient loading into lakes interacts with climate change in affecting aquatic ecosystems. Nutrient loading and climate change is a common multiple stressor combination in aquatic environments. Climate change can increase concentrations of nutrients (e.g. through evaporating water bodies), increase water temperatures (which can increase the risk of eutrophication), and cause an increase in extreme events such as flood and drought, which can alter nutrient loading patterns (e.g. through soil erosion). However, multiple stressor interactions are rarely entirely predictable or fully understood, which is why there is significant ongoing research on the topic in aquatic science and management.
The collected studies in the new special issue suggest that it is important to note variations in the dynamics of eutrophic lakes across different climate zones. Many past studies on the restoration of eutrophic lakes have been carried out in northern temperate regions. However, the papers in this special issue broaden the global coverage to include warm lakes, with studies from Denmark, Turkey, USA, Brazil, Russia, The Netherlands, Poland and China.
As a result, whilst reducing nutrient pollution is presented as the key factor for lake restoration under climate change across all studies, it is suggested that different methods to those applied in northern temperate region are needed for warm lakes. For example, the thresholds for achieving ‘clear water’ (i.e. non-eutrophic) conditions through nutrient reductions are likely to be lower in warm lakes than cold; however there still remains significant uncertainty.