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International audience; Littoral benthic diatom communities are pivotal indicators which react to coastline sources of pollution. Littoral communities, however, may be also strongly influenced by other environmental factors: we assumed that even in lakes without anthropogenic pressure, communities could be heterogeneous. To investigate the natural causes of community heterogeneity along shoreline, we sampled 58 pristine high-altitude lakes in the French Alps. Inside each lake, three different littoral stations were sampled. Water chemical composition was measured with major environmental settings. Lakes with homogeneous communities along their shoreline were dominated by pioneer species adapted to strong physical disturbances. The water renewal time in these lakes was short (a few days) and this conveyed strong turbulences. Lakes with heterogeneous communities along their shore had longer water renewal time and were dominated by high-profile diatoms that were able to compete for light and nutrients. The within-lake heterogeneity could be explained by the variability in coastline terrestrial habitats. This study illustrates how water turbulences can limit the expression of some ecological processes like interspecific competition and reduce heterogeneity when it is an overriding stressor. Finally, implications for lake managers are given in terms of monitoring efforts.

Lakes are essential ecosystems that provide a large number of ecosystem services whose quality is strongly impacted by human pressures. Optimal uses of lakes require adapted management practices which in turn rely on physico-chemical and biological monitoring. Long-term ecological monitoring provides large sets of environmental data. When such data are available, they have to be associated to metadata and to be stored properly to be accessible and useable by the scientific community. We present a data informatics system accessible to anyone who requests it. Maintained online since 2014 (https://si-ola.inrae.fr), it is originated from the Observatory on LAkes (OLA). It contains long-term data from 4 peri-alpine lakes (Lakes Aiguebelette, Annecy, Bourget, Geneva/Léman) and 24 high-altitude lakes of the northern French Alps. We describe the generated long-term data series, the data type, the methodologies and quality control procedures, and the information system where data are made accessible. Data use is allowed under the condition of providing reference to the original source. We show here how such a platform clearly enhances data sharing and scientific collaboration. Various studies referring to these data are regularly published in peer-reviewed journals; providing in fine a better understanding of lakes’ ecosystems functioning under local and global pressures.

Natural organic matter in soils contains stable semiquinone radicals, the nature of which depends on their origin and their maturation state. The relative proportions of these radicals, deduced from simulations of the EPR spectrum, constitute a signature which can be used to differentiate soils and even their horizons. It allows us to monitor the transfer of organic matter in a drainage basin from the soil to the hydrological systems, from the systems to their spillways and right up to the natural recorders (sediments, speleothems). The power of this tracing method is clearly illustrated by the determination of the catchment area and the residence time for drinking water in karst formations.

International audience; Excessive nutrient delivery into freshwater bodies results in increased eutrophication risk worldwide. Because high-frequency monitoring cannot be generalised to all rivers, methods are needed to assess eutrophication risk in contexts with scarce data. To this end, we present an assessment framework which includes: (i) a mass-balance model to estimate diffuse N and P transfer/retention in unmonitored catchments and (ii) a set of indicators based on N:P:Si molar ratios to assess the risk of eutrophication in freshwaters. The model, called Nutting, integrates variables that describe both agricultural pressures and physical attributes of catchments (climate, topography, soil). Nutting refines previous mass-balance models by describing nutrient pressures with soil N surplus and soil P content instead of N and P inputs, and by considering physical attributes not only as lumped variables over the entire area but also within river corridors. The model was calibrated on a set of 160 independent catchments across France and applied to all headwater catchments. We found that apparent N and P retention represented 53 +/- 24% and 95 +/- 29% of soil N and P surplus, respectively, and was mainly controlled by the climate and a hydrology-related connectivity index. The spatial organisation of the landscape was of secondary importance compared to the refined description of agricultural pressures. Estimated eutrophication risk was highly sensitive to assumptions about P bioavailability, hence the potential range of headwaters at risk of eutrophication spanned 26-63% of the catchments, depending on assumptions. This framework provides a generic method to assess the relative contribution of agriculture to nutrient loads and the subsequent risk of eutrophication. (V) 2014 Elsevier Ltd. All rights reserved.

The Anthropocene is characterized by a worldwide spread of hypoxia, among other manifestations, which threatens aquatic ecosystem functions, services, and biodiversity. The primary cause of hypoxia onset in recent decades is human-triggered eutrophication. Global warming has also been demonstrated to contribute to the increase of hypoxic conditions. However, the precise role of both environmental forcings on hypoxia dynamics over the long term remains mainly unknown due to a lack of historical monitoring. In this study, we used an innovative paleolimnological approach on three large European lakes to quantify past hypoxia dynamics and to hierarchies the contributions of climate and nutrients. Even for lake ecosystems that have been well oxygenated over a millennia-long period, and regardless of past climatic fluctuations, a shift to hypoxic conditions occurred in the 1950s in response to an unprecedented rise in total phosphorus concentrations above 105 mu g P L-1. Following this shift, hypoxia never disappeared despite the fact that environmental policies succeeded in drastically reducing lake phosphorus concentrations. During that period, decadal fluctuations in hypoxic volume were great, ranging between 0.5 and 8% of the total lake volumes. We demonstrate, through statistical modeling, that these fluctuations were essentially driven by climatic factors, such as river discharge and air temperature. In lakes Geneva and Bourget, which are fed by large river systems, fluctuations in hypoxic volume were negatively correlated with river discharge. In contrast, the expansion of hypoxia has been related only to warmer air temperatures at Annecy, which is fed by small river systems. Hence, we outline a theoretical framework assuming that restored lake ecosystems have inherited hypoxia from the eutrophication period and have shifted to a new stable state with new key controls of water and ecosystem quality. We suggest that controlling river discharge may be a complementary strategy for local management of lakes fed by large river systems.

International audience; Agricultural pesticide use has increased worldwide during the last several decades, but the long-term fate, storage, and transfer dynamics of pesticides in a changing environment are poorly understood. Many pesticides have been progressively banned, but in numerous cases, these molecules are stable and may persist in soils, sediments, and ice. Many studies have addressed the question of their possible remobilization as a result of global change. In this article, we present a retro-observation approach based on lake sediment records to monitor micropollutants and to evaluate the long-term succession and diffuse transfer of herbicides, fungicides, and insecticide treatments in a vineyard catchment in France. The sediment allows for a reliable reconstruction of past pesticide use through time, validated by the historical introduction, use, and banning of these organic and inorganic pesticides in local vineyards. Our results also revealed how changes in these practices affect storage conditions and, consequently, the pesticides' transfer dynamics. For example, the use of postemergence herbicides (glyphosate), which induce an increase in soil erosion, led to a release of a banned remnant pesticide (dichlorodiphenyltrichloroethane, DDT), which had been previously stored in vineyard soil, back into the environment. Management strategies of ecotoxicological risk would be well served by recognition of the diversity of compounds stored in various environmental sinks, such as agriculture soil, and their capability to become sources when environmental conditions change.

International audience; Watershed losses of phosphorus (P) have been a topic of concern for water resource managers over recent decades. To evaluate environmental policies or before implementing mitigation options at the watershed (catchment area) scale, stakeholders often need to analyze the patterns of point and diffuse sources of phosphorus. This information is often not easy to obtain in field conditions. Several statistical modeling approaches have been developed in recent years to respond to this basic operational demand. Point and diffuse sources are often evaluated from power functions established between phosphorus concentration and water discharge. Such models do not explicitly account for in-stream processes which control P concentrations in the hydrographic network and differentiate the P export dynamics of the various forms and inputs of P. To identify the phosphorus sources and evaluate their change in response to environmental policies, we developed a simple and loaded-oriented model (POPEYE - PhOsPhorus, Evaluation of the efficiencY of Environmental policy measures) that computes retention, settling and re-suspension rates of fine and coarse P fractions and their relation to P concentration of bed sediments. The model is calibrated to a long-term database (25 years), and describes the weekly water and chemical fluxes of a tributary of Lac Leman (Lake Geneva, Venoge river watershed, 240 km(2)). It adequately predicts observed values of fine and particulate phosphorus and reflects the gradual decrease of point and diffuse inputs over the studied period due to agricultural and sewage treatment policies implemented for the control of lake pollution. (c) 2012 Elsevier B.V. All rights reserved.

International audience; The impact particulate-phosphorus (particulate-P) has on eutrophication of aquatic systems that greatly depends on its composition. As a result, analysis methods for evaluating particulate-P speciation must be capable of identifying and/or quantifying the wide range of forms particulate-P can take. In the present study, we compare the particulate P speciation of the fine and colloidal fractions of riverbed sediment and suspended matter from two rivers in the Lake Geneva basin (French Alps) as determined with chemical extractions to results of a combined Transmission Electron Microscopy and Energy Dispersive Detection (TEM–EDS) analysis of the same samples. TEM–EDS provides semi-quantitative information about the distribution of P throughout the solid fraction of a sample and on the diversity of carrier phases, which are identified by their morphology and stochiometry. EDS-detectable quantities of phosphorus were found in 15–35% of the particles in the samples analyzed. As expected, particulate-P existed in a wide variety of forms, mostly associated with Al, Fe, Ca and Si. Some types of particles, often well-crystallized phosphate minerals, had high P contents (10–30%), but the dominant carrier phases of P were diffuse matrices of particles with low P contents (

Les impacts des eaux pluviales urbaines sur les milieux recepteurs sont encore mal connus. Notre recherche vise a evaluer l'impact des micropolluants des eaux pluviales urbaines sur un milieu aquatique via l'analyse de ses sediments. Le principal site d'etude est le lac du Bourget pour lequel l'analyse de carottes datees est mise en relation avec l'evolution de l'urbanisation sur le bassin-versant au cours des 100 dernieres annees. Ce papier presente dans un premier temps les elements bibliographiques ayant conduit a l'elaboration du projet et a la mise en place de la strategie d'echantillonnage et d'analyse. Puis dans une deuxieme partie, les premiers resultats sur les profils verticaux de concentrations en HAP et en PCB dans les carottes de sediments du lac du Bourget sont presentes.

Both particulate phosphorus (PP) and soluble phosphorus (SP) contribute to the eutrophication of water bodies. This research focuses on the mechanisms and factors controlling SP exports at the watershed scale in a case study located in Southern France. Variability in the P concentrations and fluxes was analysed over a period of 6 years in a 302-ha rural watershed. During most of the hydrological periods, reservoirs and pathways for PP and SP seemed to be different both in time and space; differences were greatest during storm flows of the early wet season. Their high SP fluxes and concentrations were due to the P released from agricultural soils as shown by a P mass balance downstream/upstream. During these flushing periods, soluble forms of P follow a hydrochemical behaviour quite similar to solutes and are transferred in relationship to subsurface flows, as shown by a detailed monitoring of the transition from dry to wet season on an agricultural sub-watershed.

Resume Une crue artificielle est realisee sur un troncon de ruisseau du bassin versant du Mercube (Haute-Savoie, France) afin de rendre compte du role du reseau hydrographique dans la transmission et l’emission de particules et de phosphore. Seul le phosphore d’origine diffuse est concerne. Cette experimentation se deroule en injectant de l’eau naturellement marquee par une teneur elevee en sulfates et chargee de suspensions. Elle met en evidence (1) les zones de stockage et de relargage des matieres en suspension dans le reseau hydrographique, (2) l’importance de l’effet piston sur le renouvellement des eaux en crue et (3) la capture du phosphore soluble au cours du transfert. L’augmentation du debit liee a l’onde de pression met en mouvement les sediments deposes au fond du lit. De ce fait, le phosphore est emis a l’exutoire d’abord lieaux particules remises en suspension, puis associea l’eau injectee. La contribution du reseau hydrographique a l’emission de phosphore n’est pas negligeable. Le meme phenomene se retrouve dans une crue reelle d’intensitecomparable.

Phosphorus is an important pollutant leading to lake eutrophication. Diffuse pollution accounts for a substancial share of the total phosphorus load. To improve our knowledge of this pollution, we conducted a watershed study in a small, rural, 302-ha watershed (Lake Léman area). To study the spatial distribution and temporal dynamics of phosphorus in the watershed and the corresponding variation in phosphorus speciation, 40 stormflow events over a 4- year period were analysed. We began by defining the ’state’ of the watershed using a) periodic field surveys of signs of erosion, b) the length of the flowing ditches and streams (active hydrological network) and the waterpathways on the fields, c) the overall water budget, and d) grab samples of stream water from a network of subwatersheds. Four states that reflected contrasting watershed conditions were identified. Analysis of the data on phosphorus flux at the outlet of the watershed, in conjunction with the observations on the state of the watershed, allowed us to develop a conceptual model of phosphorus export from the watershed and several hypotheses about phosphorus transfer. (© Inra/Elsevier, Paris.), On cherche, à travers l’étude d’un bassin versant rural, à identifier les mécanismes de la pollution diffuse phosphorée, ses modalités d’émission et de transport et ses impacts potentiels sur les milieux récepteurs. Les exportations de phosphore ont été étudiées pendant 4 ans sur le Mercube, bassin versant rural de 302 ha sans pollution ponctuelle, situé sur la rive française du Léman. Le principe de l’étude consiste à comparer des « états de bassin » avec des flux et des spéciations mesurés à son exutoire. La définition de l’état de bassin repose sur des campagnes d’observation et de mesures des écoulements présents sur le bassin versant. Quatre états reflétant des situations hydriques contrastées ont été définis. Ils se distinguent par la diversité spatiale des différents stocks de phosphore mis en jeu. Leur succession saisonnière décrit un cycle étroitement lié aux cycles culturaux et météorologiques. Afin de comprendre l’influence de ces états sur les quantités de phosphore émises vers le lac et sur sa spéciation, une quarantaine de crues ont été échantillonnées à l’exutoire du bassin.Cette analyse des transferts diffus de phosphore nous amène à proposer un modèle typologique des exportations de phosphore. Elle aboutit aussi à renouveler les conceptions concernant les processus de transfert des formes solubles et particulaires de phosphore. (© Inra/Elsevier, Paris.)

Resume Ce papier presente les resultats d'une etude sur les transferts des nutriments (P, N) et la qualite de l'eau, menee sur un petit bassin versant (14 ha) en milieu rural, situe en bordure du Lac Leman. L'etude du bilan annuel et de la variabilite des concentrations en N et P permet d'evaluer les risques de degradation des eaux lies aux pratiques agricoles. L'analyse d'une vingtaine de crues nous a permis de degager 3 types d'evenements: (1) les crues liees surtout a une mise en charge de la nappe et caracterisees par des exportations limitees de N et de P; (2) les crues a forte composante de ruissellement qui exportent surtout de grandes quantites de P sous forme particulaire; (3) les crues a ecoulement hypodermique important qui exportent beaucoup de N mais aussi de P sous forme soluble. Les flux sortant du bassin experimental s'ecoulent vers un marecage et a l'exutoire de ce marais, on constate une nette amelioration de la qualite de l'eau par denitrification et par insolubilisation et decantation de P. La gestion et la lutte contre la pollution diffuse agricole passe ainsi par un amenagement a la fois de la zone agricole elle-meme et des differentes zones tampons le long du parcours des eaux. Le type d'amenagement n'est pas forcement le meme pour N et pour P. Dans certains cas, il peut meme apparaitre des effets contraires.

L'originalite de la pedogenese sur calschistes sedimentaires, en altitude (etage subalpin), reside dans l'homogeneite du residu de decarbonatation (plaquettes de micas de taille limons fins). Au sein des sols developpes en place, la principale evolution qui se manifeste entre l'alterite et la surface du sol, est une microdivision de ces particules limoneuses. Celle-ci s'accompagne d'une disparition du systeme de macroporosite herite de la decarbonatation de la roche et de l'apparition, dans l'horizon (B), d'un systeme de micropores (.)

En altitude, l'alteration des calcschistes sedimentaires (calcshales) conduit a des sols contenant une teneur elevee en limon fin, de composition mineralogique essentiellement micacee. La pedogenese se caracterise sur ce type de roche, par une argilisation importante due a une microdivision des micas, vers la surface du sol. Ce phenomene entraine une profonde reorganisation de la phase solide, de l'espace solide, de l'espace poral et en fin de compte, conditionne les proprietes hydriques des sols. Dans ce premier texte, un ensemble de methodes de mesure et d'observation est employe pour decrire l'evolution de la geometrie du systeme de porosite herite de la roche, apres sa decarbonatation (...)

International audience; The present article describes a first attempt to use infrared spectroscopy to trace the origin of suspended river sediments. Fifty samples of the main potential sediment sources within a small catchment area (990 ha) in the French Alps were collected and compared with samples of suspended sediment from the river, collected on various dates during 2006 and 2007 using sediment traps. Two major categories of sediment source were identified: topsoils and river channel sediments. For the qualitative part of the study, each of these two main categories was divided into two sub-categories, that is to say, cultivated and pastureland topsoils, and riverbed and riverbank sediments. Discriminant analysis on the source samples showed that Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy can be used to differentiate between the four potential source materials. To determine whether or not immersion in the river altered the infrared spectra of these source materials, we measured the infrared spectra of samples that had been immersed in the river, in litter bags, for periods of up to 24 days. Immersion did not cause any major changes in the infrared spectra. The contribution of each type of source material to the suspended sediment in the river was quantified using partial least squares (PLS) analyses of DRIFT spectra to compare actual river sediment samples with an experimental model. This model was produced from the DRIFT spectra of a range of calibration samples produced by mixing source material samples in different ratios. The predictions of the model were valid and fell within the confidence interval calculated for the calibration set. Comparisons between suspended sediment samples and the model indicate that the predominant source of the sediment is riverbank erosion, which, in this case, is probably due to trampling by cattle.

Diffuse pollution should be recognized as a landscape-level phenomenon. As such, it requires an observational approach consistent with the complex structure and function of the landscape system. We developed a landscape-level approach to study the transfer of phosphorus in rural areas of the Lake Champlain and Lac Leman basins. We began by developing a concept of P dynamics that captured some of the diversity and complexity of P movement through the land (transfer system). Given this initial concept of the diffuse pollution in the landscape, we adopted a synoptic watershed sampling strategy to begin the quantitative description of diffuse P pollution. Data from these types of studies were then analyzed using multiple regression to infer connections between activities on the land and phosphorus flux to surface waters. Our inferences include: 1) land cover determines phosphorus flux during high flow but not during low flows periods, 2) during high flow events, natural wetlands are a significant sink for diffuse phosphorus in surface waters, 3) fluxes and concentrations are higher when the basins are intensively plowed, 4) in the context of plowed areas, agricultural practices as opposed to land cover is a more important determinant of phosphorus flux in watersheds, and 5) the position of elements in the landscape is an important factor controlling diffuse phosphorus pollution. The method and basis for arriving at these conclusions are discussed. We suggest that synoptic sampling of water quality over extensive areas in a landscape, coupled with multiple regression to analyze relationships among P fluxes and landscape variables, is an appropriate tool for determining driving factors, analyzing the diversity of processes, and finding generality in complex landscape systems.

Colloque « Eaux et milieux aquatiques continentaux » à Rennes le 2 octobre 2012.; National audience; Alpine lakes are influenced by multiple forcing factors acting at global or local scale. Ecological responses, changes in biodiversity, community structure reflect their interactions. Their understanding requires approaches that are spatially and temporally nested. In particular, highlighting the long-term trend requires physico-chemical and biological surveys organized in the frame of Observatory, including paleolimnological approaches and more specific studies to identify short-term ecological dynamics. The Alpine Lakes Observatory (SOERE) enables to trace the evolution of the major lakes of the French Alps, showing that the effects of global warming on biodiversity are lake declined locally, depending on the local characteristics.; Les lacs alpins sont sous influence de facteurs de forçage multiples, agissant à l’échelle globale ou locale. Les réponses écologiques, les changements de biodiversité, de structure de communautés traduisent ces interactions. Leur compréhension nécessite des approches emboîtées, spatialement et temporellement. En particulier, la mise en évidence de tendance sur le long terme nécessite des suivis physico-chimiques et biologiques pérennes dans le cadre d’Observatoire, incluant des approches de paléolimnologie et des études plus ponctuelles permettant de préciser des dynamiques écologiques à court terme. L’Observatoire des Lacs Alpins (SOERE) permet ainsi de retracer les évolutions des principaux lacs des alpes françaises, en montrant que les conséquences du réchauffement climatique sur la biodiversité lacustre sont déclinées localement, en fonction des caractéristiques locales.

This research project entitled « Pastor » is devoted to the study of the survival and dissemination of fecal bacteria contaminants originated from cattle, in soil and surface water. It focuses on microbial contamination by Escherichia coli in relationship with dairy grazing of alpine rangelands. E. coli is considered as a global indicator of fecal contaminations. Studies have been carried both at the plot and at the watershed scale. They deal with : 1) the dynamics of E. coli populations, including pathogenic STEC (Shiga-toxin producing E. coli) strains, released in the mountain environment ; the objective is to characterize survival and storage ompartments of E. coli in soil following their release by cattle feces ; the population dynamics of E. coli in soils is compared with dynamics of typical soil inhabitants (the fluorescent Pseudomonas spp.), in order to reveal specific adaptive strategies of E. coli ;2) the identification and characterization of the grazing areas providing specifically a high contribution to fecal contamination of surface water ; this was carried out by quantifying and modeling E. coli transfers from soil to water, with the aim to link together E. coli fluxes monitored at the watershed outlet, grazing conditions and hydrologic properties of the watershed. The output of the model is of interest to identify the critical source areas. Further assessment of the groundwater compartment is needed to improve our understanding of E. coli ecology especially with regards to the outlet peaks unrelated to stromflows. The operational interest of « Pastor » concerns the prevention of fecal pollution of surface water and the relevance of E. coli as an indicator of fecal contamination. The knowledge of critical source areas is an important information for management of pastured watersheds., L’objectif de ce projet mené dans le cadre du programme GESSOL 2 est de comprendre et modéliser la survie et la dynamique de transfert dans les déjections, les sols et les eaux, de contaminants fécaux bovins, en relation avec les pratiques pastorales et la variabilité des milieux. Les suivis sont centrés sur Escherichia coli et incluent des données sur les souches pathogènes STEC (Shiga-toxin producing E. coli). Des suivis complémentaires portant sur Pseudomonas spp fluorescents, populations typiques des sols, fournissent des éléments de comparaison importants. Les recherches sont réalisées dans un alpage des Alpes du nord, à l’échelle station-parcelle et bassin versant. L’article présente une vue d’ensemble de la démarche d’étude, des méthodologies et des résultats obtenus, puis se focalise sur les acquis concernant le comportement de E. coli dans les sols et sur les apports de la modélisation des transferts à l’échelle bassin versant. Les résultats sont discutés dans une double perspective, celle d’une synthèse présentant le fonctionnement du bassin versant pâturé comme un système de transfert de contaminants fécaux et celle de réflexions opérationnelles relatives à la gestion pastorale., El proyecto “Pastor” trata de la supervivencia y de la diseminación de los contaminantes microbianos del suelo hacia las aguas. Apunta la contaminación microbiana del agua por E. coli (indicador de la contaminación fecal) en los prados alpestres en relación con los pastos de lechera. La demanda social en términos de calidad microbiana del agua está importante, incluyendo los Alpes norteños franceses, región de reserva de agua. Las contaminaciones se deben en parte a las prácticas de pastizales. Un inquietante desenlace está la ocurrencia de animales portadores sanos de E. coli potencialmente patogénicos para los humanos y cuya diseminación por los animales de granja está posible. La calidad del agua en las zonas de pastizales entra en debates más amplios sobre la gestión sostenible de los recursos de aguas subterráneas bajo pastos. Las investigaciones desarrollas en el proyecto “Pastor” tratan de : 1) la dinámica de las populaciones de E. coli, incluyendo las tensiones debidas a las STEC patogénicas, una vez liberadas en el medio ambiente montañoso ; el objetivo está caracterizar los compartimentos de supervivencia y de almacenamiento de E. coli en los suelos después de su depósito por las deyecciones del ganado, y comparar con la dinámica de las populaciones típicas del suelo (Pseudomonas spp. fluorecens) para la evaluación de las estrategias adaptivas de E. coli. 2) la identificación y la caracterización de las zonas de pastos que contribuyen a la contaminación fecal de las aguas de superficie en una cuenca vertiente alpestre ; Se midió la cuantidad de E. coli que está transferida de las diferentes zonas de pastos hacia el agua, con la finalidad de ligar el stock de E. coli y el flujo a la salida de la cuenca vertiente, al funcionamiento del pasto y a las propiedades hidrológicas de la cuenca vertiente. “Pastor” incluye también un análisis del funcionamiento de la cuenca vertiente en términos de transferencia de los contaminantes fecales y de modelización del flujo bacteriano. La información necesaria para la modelización incluye los regímenes de exportación a la salida de la cuenca vertiente, condición de transferencia en la cuenca vertiente, y el potencial de liberación de las diferentes unidades de pastos. El rendimiento del modelo estará importante para la gestión mejorada de los recursos en agua en los pastos alpestres. La significación práctica de “Pastor” concierne la prevención de la contaminación fecal del agua y la pertinencia de E. coli como indicador de la contaminación fecal. Es necesario tener una evaluación más precisa del compartimento del agua subterránea para mejorar nuestro conocimiento de la ecología de E. coli especialmente para los picos de salida no ligados a los flujos. El conocimiento de las zonas de contaminación activa está importante para la gestión de los circuitos de pastos, de las zonas de abrevadero del ganado, de los pasos de arroyos, así como el cierre de las zonas de riesgo. Estas medidas de protección están más bien costosas a aplicar. Sin embargo, a pesar del hecho que una proporción muy pequeña de contaminantes microbianos llega al agua de superficie, pueden tener consecuencias muy significativas en términos de salud humana y animal.