Although the research history on biological diversity in subsurface water typically lags behind that of surface freshwater, considerable efforts amongst scientists for the second half of the 20th century have revealed the unexpectedly high diversity of living forms in groundwater. The nineties’ literature comprises not less than 10 books dealing with the biology and ecology of groundwater, a publication rate probably unequalled in many other research fields (6-15). However, none of these books have attempted to provide standard protocols and guidelines for estimating and maintaining groundwater biodiversity, despite the persuasive alteration of groundwater resources and expectedly high extinction rates of species. Therefore, the transfer and practical implications of basic knowledge in groundwater ecology is still severely limited by the lack of appropriate tools for assessing and conserving biodiversity. The present project is resolved to fill this gap and will provide new data and innovative methods that are of critical importance in advancing the assessment and conservation of groundwater biodiversity. Major creative products will concern both the way to look at, to assess, to predict and to conserve biodiversity in European groundwater.

An integrated approach of groundwater biodiversity
Whereas previous attempts to assess subterranean biodiversity have only relied upon the examination of cave assemblages (16, 17), the present project encompasses a large spectrum of groundwater habitats including the unsaturated and saturated zones of karst systems as well as the hyporheic and phreatic zones of alluvial groundwater. The consortium has a strong taxonomic expertise that covers the majority of biological groups living in groundwater including nematods, gastropods, hydracarids, oligochaetes, copepods, ostracods, syncarids, isopods, amphipods, and amphibians. Additionally, DNA-analysis will be used as an explorative and complementary method for estimating the “hidden” biodiversity within selected cryptic taxa. Such an integrated approach of biodiversity has little precedent equivalents in groundwater and freshwater ecology where biodiversity between related habitats (e.g. lakes, ponds, and streams) and biological groups has been usually treated separately.

Standard methods for assessing and predicting regional biodiversity.
The project will provide a tool-box that includes several validated methods for: 1) determining the reliability of patterns of regional biodiversity revealed by the mapping of existing data; 2) predicting overall species richness based on biodiversity indicators in regions with incomplete data set; 3) obtaining by means of a standardized field sampling method an unbiased estimate of groundwater biodiversity in regions for which no data are existing. To date, none of these three important issues have been addressed, thereby severely restricting the usefulness of distribution maps for the assessment and conservation of groundwater biodiversity.

A scale-oriented conservation strategy of groundwater biodiversity
Resurfacing “below-feet” biodiversity and identifying regional hotspots of diversity is a critical step towards conservation and would be, of course, a major task of the project consortium. However, the appropriateness of conservation measures strongly depends upon the partitioning of the species pool among the different units of a region. This project is the first attempt to apply an innovative hierarchical method of examining groundwater biodiversity in selected regions. We would analyze the partitioning of the regional species pool among well defined units of a 4-level hierarchy. At the highest level, gamma diversity encompasses a major region (several 100 km2), that is characterized by a set of hydrogeologic and biogeographic features. A region contains numerous groundwater systems (2nd level), each of them draining towards a river. A groundwater system includes several karst and alluvial aquifers (3rd level). At the lowest level, we distinguish between the vadose and saturated zones of karst aquifers and the phreatic and hyporheic zone of alluvial aquifers. Using this hierarchical approach of biodiversity, the project consortium aims to identify the spatial scale of relevance for preserving groundwater biodiversity, so that effective conservation measures could be taken at the appropriate administrative level. We believe that a unified operational conservation strategy for groundwater biodiversity may emerge from the comparison of the partitioning of biodiversity between selected regions.