Springs: neglected key habitats for biodiversity conservation

In spite of being one of the main components in the longitudinal zonation of lotic systems, spring habitats have received much less attention than lakes and streams/rivers, and are still widely understudied. However, springs, are seriously threatened by several direct and indirect impacts, the most important being their capture to obtain drinking water, hydroelectric power, etc. This pressure will increase even more in the future: due to climate change, a reduction in, and increasing irregularity of, precipitation being predicted for many areas, including the Alps. In spite of anthropogenic pressures, springs are frequently the last unpolluted, high quality freshwater environments in densely populated areas, acting as refugia for the most pollution-sensitive organisms. The outstanding importance of these habitats for the conservation of freshwater biodiversity is slowly but increasingly being recognized. In an attempt to contribute to the spread of knowledge on crenobiology and to promote awareness of the relevance of these habitats for nature protection, the idea of grouping contributions on crenic biology and ecology in a special issue of an international journal arose. All available spring morphological types, from seepages and tufa springs to large karstic rheocrenes, were considered. The involvement of many taxonomic experts provided the opportunity to study a wide range of different organisms. This Special Issue contains 13 papers, at least 7 of which are mainly based on results obtained during the CRENODAT Project ('Biodiversity assessment and integrity evaluation of springs of Trentino - Italian Alps - and long-term ecological research', 2004-2008). Most papers deal with the biodiversity and community ecology of a variety of autotrophic and heterotrophic, macroscopic and microscopic groups of organisms. Several evaluate the relative importance of morphological (from microhabitat to large scale), physical, and chemical factors in determining community composition and structure. Some discuss the conservation implications of the observed patterns. One even applies palaeolimnological techniques to a crenic habitat, showing the effects of land use and management practices around the spring-head. Spatial and temporal changes (from seasonal to longterm) are also considered.