title: A global review on ambient Limestone-Precipitating Springs (LPS): Hydrogeological setting, ecology, and conservation.
abstract: Springs are biodiversity hotspots and unique habitats that are threatened, especially by water overdraft. Here we review knowledge on ambient-temperature (non-geothermal) freshwater springs that achieve sufficient oversaturation for CaCO3 -by physical CO2 degassing and activity of photoautotrophs- to deposit limestone, locally resulting in scenic carbonate structures: Limestone-Precipitating Springs (LPS). The most characteristic organisms in these springs are those that contribute to carbonate precipitation, e.g.: the mosses Palustriella and Eucladium, the crenophilous desmid Oocardium stratum, and cyanobacteria (e.g., Rivularia). These organisms appear to be sensitive to phosphorus pollution. Invertebrate diversity is modest, and highest in pools with an aquatic-terrestrial interface. Internationally, comprehensive legislation for spring protection is still relatively scarce. Where available, it covers all spring types. The situation in Europe is peculiar: the only widespread spring type included in the EU Habitat Directive is LPS, mainly because of landscape aesthetics. To support LPS inventorying and management to meet conservation-legislation requirements we developed a general conceptual model to predict where LPS are more likely to occur. The model is based on the pre-requisites for LPS: an aquifer lithology that enables build-up of high bicarbonate and Ca(2+) to sustain CaCO3 oversaturation after spring emergence, combined with intense groundwater percolation especially along structural discontinuities (e.g., fault zones, joints, schistosity), and a proper hydrogeological structure of the discharging area. We validated this model by means of the LPS information system for the Emilia-Romagna Region (northern Italy). The main threats to LPS are water diversion, nutrient enrichment, and lack of awareness by non-specialized persons and administrators. We discuss an emblematic case study to provide management suggestions. The present review is devoted to LPS but the output of intense ecological research in Central Europe during the past decades has clearly shown that effective conservation legislation should be urgently extended to comprise all types of spring habitats.
authors.affiliation: Museo delle Scienze - MUSE, Limnology and Phycology Section, Corso del Lavoro e della Scienza 3, I-38123 Trento, Italy. Electronic address: marco.cantonati@muse.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Cantonati
authors.affiliation: Emilia-Romagna Region, Geological Seismic & Soil Survey, Bologna, Italy; University of Parma, Dept. Physics & Earth Sciences, Parma, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Segadelli
authors.affiliation: University of Parma, Dept. Physics & Earth Sciences, Parma, Italy.
authors.forename: Kei
authors.initials: K
authors.lastname: Ogata
authors.affiliation: University of Innsbruck, Faculty of Geo- and Atmospheric Sciences, Institute of Geology, Innrain 52f, A-6020 Innsbruck, Austria.
authors.forename: Ha
authors.initials: H
authors.lastname: Tran
authors.affiliation: University of Innsbruck, Faculty of Geo- and Atmospheric Sciences, Institute of Geology, Innrain 52f, A-6020 Innsbruck, Austria.
authors.forename: Diethard
authors.initials: D
authors.lastname: Sanders
authors.affiliation: University of Tübingen, Institute of Evolution and Ecology, Tübingen, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Gerecke
authors.affiliation: University of Innsbruck, Faculty of Biology, Institute of Botany, Sternwartestrasse 15, Innsbruck A-6020, Austria.
authors.forename: Eugen
authors.initials: E
authors.lastname: Rott
authors.affiliation: Alma Mater Studiorum University of Bologna, Dept. Biological, Geological & Environmental Sciences - BiGeA, Bologna, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Filippini
authors.affiliation: Alma Mater Studiorum University of Bologna, Dept. Biological, Geological & Environmental Sciences - BiGeA, Bologna, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Gargini
authors.affiliation: University of Parma, Dept. Physics & Earth Sciences, Parma, Italy.
authors.forename: Fulvio
authors.initials: F
authors.lastname: Celico
mesh_terms: D059001:Aquatic Organisms / Q000145:classification; D044822:Biodiversity; D002119:Calcium Carbonate / Q000032:analysis* / Q000737:chemistry; D011232:Chemical Precipitation; D000074067:Conservation of Water Resources / Q000379:methods*; D004784:Environmental Monitoring / Q000379:methods*; D008962:Models, Theoretical; D060985:Natural Springs / Q000737:chemistry*
chemical_list: D002119:Calcium Carbonate
keywords: Biocalcification; EU Habitat Directive; Freshwater conservation; Limestone-Precipitating Springs (LPS); Spring habitats; Spring-Associated Limestones (SAL); Travertines; Tufa Springs