Impact of climate and degree of isolation on the biological interactions and biodiversity in lakes - from the High Arctic to the tropics, from continents to islands and from the past to the present with a view to the future

Prof., Dr. scient Erik Jeppesen, National Environmental Research Institute

The purpose of the project is to provide new knowledge of the importance of biodiversity and its impact on the biological interactions in lakes located in different climate zones and with different species diversity conditioned by the differences in distance from the continents. Analysis will be made of the lakes in their present state and of their development during the past 200-300 years, the latter via analyses of lake sediments. Combined with samples taken previously in lakes from both the northern and southern hemisphere the data will be used to evaluate how climatic changes will influence biodiversity and the development in biological interactions and the ecological state of lakes.

Investigations will be made in  the Azores and Tasmania. In each area 15-30 lakes, characterised by differences in depth, nutrient level and location above sea level, will be selected and sampled once in late summer. For each lake the sampling process involves: a) a quantitative description of the biological communities and of biodiversity. All components will be included, from fish (standard fishing using gill nets and traps), plankton, bottom invertebrates, submerged macrophytes and microorganisms; 2) a description of the food web structure and interactions using stable isotope analysis; 3) determination of fish growth using otolith analysis.  4) description of changes in the biological communities and ecological state over the past centuries and if possible, millennia. Sediment cores will be analysed for biological remains, and analyses of stable isotopes will be undertaken. In addition, age determination of the cores will be conducted.