A biological survey of high mountain and high latitude lakes across Europe: Aims, sampling strategy, methods and main achievements

There are over 50,000 remote mountain lakes across Europe, occurring from the Arctic to southern Iberian Peninsula. Previous work on these systems has tended to focus on developing a detailed understanding of the structure, functioning and dynamics of individual, representative sites. One of the central objectives of the EU-funded EMERGE project was to undertake a comprehensive evaluation of the status of remote mountain lake ecosystems across Europe. To do this, a pan-European survey was designed to investigate the main patterns of variability of key organisms. Twelve mountain regions, termed Lake Districts, were selected covering the main geographical and environmental gradients across upland Europe. Between 6 and 85 lakes in each Lake District were surveyed. This paper provides an introduction to a special issue of 'Fundamental and Applied Limnology-Advances in Limnology Series' which brings together a series of studies using the data collected as part of this pan-European study. The paper introduces the aims of the survey and describes the sampling strategy and analytical methods employed. A number of studies undertaken are presented and a summary of the conclusions from each of the individual studies is provided.