Climate change and other anthropogenic factors affect lakes in many ways that can lead to important effects on freshwater ecosystems. For this reason, the Swiss Federal Office for the Environment (FOEN) is currently evaluating options to add a nation-wide lake temperature monitoring program to their monitoring activities, which already includes a network of river temperature monitoring.
In this work, we discuss the benefits and limitations of temperature data obtained by a monitoring program depending on the spatial and temporal resolution of the measurements. We conclude that for accurately observing trends in the thermal structure of lakes caused by climate change, a high time resolution is required that cannot be provided by traditional temperature profiling. We therefore recommend installing moorings where temperature can be continuously monitored.
Individual lakes react differently to climate change according to internal and external parameters, such as their size, trophic state, or altitude. These different reactions should be considered when selecting lakes to be included in the monitoring network. We therefore discuss the factors that influence a lake’s reaction to climate change, and present four different scenarios for a monitoring network. The first scenario includes the modelling of lakes that are currently monitored, without adding new monitoring sites. The second scenario represents the installation of moorings in all lakes above a certain size. The third scenario is the monitoring of lakes at different altitudes. Scenario 4 is a combination of Scenario 2 and Scenario 3 with the addition of other lakes with various characteristics to broaden the perspective. The advantages and disadvantages of the four scenarios are assessed.
Finally, we discuss the opportunity of measuring other parameters (e.g., meteorological forcing, chemical parameters…) that would increase the coherence and impacts of the monitoring program. We also shortly discuss options for data management and data quality control.