Paleolimnological techniques applied to springs habitats: Challenges and limits as highlighted by the CRENODAT project (southeastern Alps, Italy)

摘要

Springs are vital resources of drinking water for human life. Yet in recent time they are seriously endangered, and most need intervention to preserve or recover their habitats, protect the aquatic environment, and prevent and reduce pollution. However, recognizing the original "natural" and pristine state of a spring can be difficult because the monitoring programs included in policies to promote sustainable water use are rela-tively recent (EUROPEAN UNION 2000), well after the beginning of anthropogenic impact. Ideally we would have past "pic-tures" of present-day springs that reveal a "past" time with no detectable human influence. In the absence of historical data, these habitat pictures must be recreated by applying standard techniques used for palaeoenvironmental studies in other dep-ositional environments, such as those used for lakes (SMOL 2002, CoHEN 2003). To do so, habitats would ideally have had continuous sedimentation (low energy flow), no disturbance (anthropogenic or natural), and sediment rich in proxies and datable. However, most of the existing springs have flow ve-locities and seasonality too high to allow deposition, seriously challenging the application of paleolimnological approach in this kind of environments. This challenge is probably respon-sible for the paucity of studies in the literature concerning paleo-aspects in springs, especially when considering the biological-ecological aspects (WILLAMs 1996, WILLIAMs & WILLIAMSON 1997, REAVIE et al. 2001), with the exception of karstsprings deposits (ANDREWS 2006) and lakes or ponds fed by groundwater or directly by submerged or littoral springs (EuSTERHUES et al. 2005).Within the frame of the CRENODAT Project, `Biodiversity assessment and integrity evaluation of springs of Trentino (Italian Alps) and long-term ecological research," we had the unique opportunity to select study sites among a complete set of more than 100 monitored springs to test the feasibility of the paleo-approach. This work presents the sites selection criteria, methods, and preliminary results of our test study to help de-fine challenges and limits for future paleo-springs research developments.