Use of benthic organisms from multiple taxonomic groups for the conservation-oriented classification of spring habitats: Neglected and threatened key habitats for biodiversity conservation

Springs are unique habitats. They are endangered by exploitation (tapping), and by the predicted reduction in precipitations. The CRENODAT Project was financed by the Autonomous Province of Trento (Italian Alps), and characterized by its broad approach to the spring biota (cyanoprokaryota, algae, lichens, bryophytes and vascular plants, ciliates, meio- and macrozoobenthos). The springs sampled are located over a wide range of altitudes and lithologies; the majority is small and with a stable temperature all over the year. Mineral content ranges from hyperdilute waters to iron and sulphur springs, and pH from very low values (iron springs) to those typical of limestone aquifers. This contribution develops a spatial classification scheme using biological data from 86 sites. Our goal was to test the consistency of classifications based on different taxonomic groups. Direct ordination methods were used to identify the major explanatory environmental variables for each taxonomic group. End-group classifications were validated using both external and internal criteria, and compared using randomization tests. Several groups distinguished well-defined spring-types, with little overlap between them. The biological data were used to develop an integrated classification, that was then interpreted in relation to abiotic variation. End-group structure can effectively be discriminated by altitude, lithology, shading, and discharge.