Title:

Ecological consequences of climate change on thermal stratification, transparency and anoxia of sensitive lake ecosystems

 

Goals and aims:

It is the major goal to improve predictive models for lake stratification and mixing and their possible ecological consequences and specifically to analyse how future climate change scenarios might affect selected and vulnerable lakes in Denmark.

 

Background:

The future regional climate is expected to have higher average temperature, more frequent storms and maybe higher precipitation. All three types of changes will have fundamental influence on lake ecosystems by changing water temperature, patterns of thermal stratification and mixing as well as input of dissolved organic matter from terrestrial sources. Thermal stratification and mixing is a complex function of temperature, wind impact and in-lake features such as size, morphometry and optical properties. The future climatic scenario is most likely to lead to higher temperatures, shallower thermoclines and reduced vertical mixing of the water column. These alterations may pose serious threats to invertebrates and fish in vulnerable lake ecosystems by inducing anoxic lake bottoms or increasing the length of anoxia during summer stratification. Even the pelagic species of phytoplankton, zooplankton and fish are susceptible to such changes through altered temperature, optical conditions and vertical extension of the warm surface waters. Thus, a change in the climate has major ecological consequences for lake ecology.

 

Project description and Methodology:

The project has its focus on the physical forcing on lakes by climate and weather and thus should be developed in the interface between regional climate models and physical limnology. We therefore expect the Ph.D. student to have a good educational background within modelling. With respect to methodology the project can take advantage of the present regional climate models and combine these with available limnological data for selected Danish lakes. One major goal is to scale the regional climate models to a relevant lake sizes and to adapt them to extract the physical fields that are relevant to estimates of lake properties. The coupling of lake and climate models and a comparison of coupled model output with new data of temperature, mixing, optical conditions and oxygen distribution in vulnerable Danish lakes will enable a new validation of regional climate models.

 

The project is carried out in cooperation between DMI and the University of Copenhagen.

 

 

Contact persons:

University of Copenhagen: professor Morten Søndergaard ([email protected])

DMI: seniorforsker Ole Bøssing Christensen ([email protected])