Incorporation of Groundwater Ecology in Environmental Policy

CHAPTER 11.2

Incorporation of Groundwater Ecology in Environmental Policy DAN L. DANIELOPOL,a CHRISTIAN GRIEBLER,b AMARA GUNATILAKA,c HANS JU¨RGEN HAHN,d JANINE GIBERT,e F. MERMILLOD-BLONDIN,e GIUSEPPE MESSANA,f JOS NOTENBOOMg AND BORIS SKETh a

Austrian Academy of Sciences, Institute of Limnology, Mondseestr. 9, AT5310 Mondsee, Austria; b GSF-National Research Center for Environment and Health, Institute of Groundwater Ecology, Ingolsta¨dter Landstrasse 1, DE85764 Neuherberg/Mu¨nchen, Germany; c Department of Ecotoxicology, Center for Public Health, Medical University of Vienna, Wa¨hringer Strasse 10, A-1090 Vienna, Austria; d Arbeitsgruppe Grundwassero¨kologie Universita¨t KoblenzLandau, Campus Landau Abt. Biologie, Im Fort 7, D-76829 Landau, Germany; e Universite´ Claude Bernard Lyon 1, UMR CNRS 5023 EHF, Equipe d’Hydrobiologie et Ecologie Souterraines, Baˆt FOREL, 43 Bd 11/11/ 1918, FR-69622 Villeurbanne cedex, France; f Istituto per lo Studio degli Ecosistemi CNR – ISE, Sede di Firenze, Via Madonna del Piano, IT-50019 Sesto Fiorentino/Firenze, Italy; g Milieu- en Natuurplanbureau, Netherlands Environmental Assessment Agency, Postbus 303, NL-3720 AH Bilthoven, The Netherlands; h University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, PP2995, SI-1001 Ljubljana, Slovenia

11.2.1

Introduction: Groundwater Science and the New Order

In the European Community (EC) ca. 75% of the inhabitants use groundwater (GW) as drinking water, for food production and for domestic and/or industrial needs.1 Therefore information about the way high-quality GW originates and/or can be protected is of interest for a broad spectrum of Europeans, from laypersons to policy- and decision-makers. The recent release of the European Union (EU) Groundwater Directive (GWD)2 offers a new order which should 671

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ensure the sustainability of the exploitation of GW reserves and at the same time should protect this resource from overall pollution. Moreover, it is expected to offer better protection of valuable to water storage sites, especially wetlands, which strongly depend on GW. The new GWD develops the legislative framework already mentioned in Article 17 of the Water Framework Directive (WFD)3 (see Chapter 3.1). It has three major objectives: (1) to maintain a good chemical status of GW exploitable resources, (2) to prevent/limit GW pollution and (3) to develop studies on pollution trends in order to improve the water quality of GW bodies. The implementation of this ambitious long-term programme, as presented in the various contributions of this book, points out the need for new research and development strategies combined with adapted regulatory policies. From this new order a strong GW science accompanied by pragmatic policy decisions is emerging where hydrology, hydrochemistry and water planning are the major actors. What is missing in the recent GWD is the integration of GW ecology information as a useful complement to GW science even if this plea was repeatedly expressed.4,5 One could argue6 that this is due to a lack of data on the functioning of groundwater ecosystems and on the practical use of ecological information for the monitoring and/or protection measures of GW bodies. However, this is not really correct because a whole corpus of knowledge which forms the core of what is now called the ‘‘new groundwater ecology’’ exists (e.g. Refs. 7–9) and is being rapidly developed by various European scientific groups. Research projects of these latter exist in various European countries and were inter alia also financially supported by the EC, e.g. PASCALIS (Protocols for the Assessment and Conservation of Aquatic Life in the Subsurface).10 Apparently, at the present time we suffer from lack of effective communication between scientists dealing with ecological aspects of GW and water planners and/or water policy-makers. The recent efforts of the Directorates for Environment and Research of the European Commission to improve communication between these various partners is therefore a welcome initiative,11 strongly supported by many specialists12–14 and reinforced through the various contributions of this book (e.g. Chapters 1 and 2.1). In the following, we offer some practical ideas of how ecological information can be usefully integrated in future European GW management policies.

11.2.2

The New Groundwater Ecology: Its Interest for Water Management Projects and/or Water Policy Planners

Groundwater ecology deals with structural and functional aspects of the organisms which inhabit the subsurface and with the relationships between these organisms and their surrounding aquatic environment.7 Groundwater ecology emerged at the beginning of the 20th century from natural history research dealing with descriptive aspects of subterranean organisms, their adaptive morphology, their physiology, systematics and biogeography as well

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as from observation on the hydrology, geomorphology and geochemical characteristics of various parts of the subsoil. The ‘‘new groundwater ecology’’ has existed for about 25 years.15–20 It deals with the study of ecosystems (structure and processes), with organismic assemblages and their dynamics, with relationships between subterranean and surface ecosystems, with the biological diversity of subterranean animals observed at various temporal and spatial scales and with the impact of anthropogenic pollution. A very important aspect of the new groundwater ecology is the emphasis put on ecosystem management with its instrumental aspects on monitoring and remediation schemes as well as with protection measures. Scientists involved in this new approach, as compared to the previous generation of naturalists, try to enforce the link between their research and the socioeconomic aspects of water management. Groundwater ecosystems are now more and more valued through their capacity to provide services and goods indispensable for the well being of human society and for the functioning of natural ecosystems (Table 11.2.1). Within the new groundwater ecology, students are in a very favourable position to use not only scientific arguments for environmental regulation and/ or political decisions but also ethical criteria (for instance when planning strategies for conservation of GW habitats and their unique organisms).21,22 Groundwater is an invaluable resource, which should be enjoyed by present

Table 11.2.1

Services and goods provided by groundwater ecosystems (modified from Ref. 4).

Ecosystem services

Ecosystem goods

1. Self-purification: purification of wa-

1. High-quality, safe drinking water

ter (through microbiological and physicochemical processes) Attenuation/or elimination of chemical contaminants (natural organic compounds, organic pollutants) where soil functions as a filter and biodegradation medium; has a strong link to long-term resource availability Provision of water for the environment as a conditions for the function of surface ecosystems (springs, brooks, lakes, wetlands, wet grasslands, estuarine and near-shore marine ecosystems). Sets hydrogeochemical conditions for subterranean and/or surface aquatic communities Maintain structural complexity through the landscape

for human consumption and the availability of a reliable water source Stable supply of water for other human needs (agriculture, industry, domestic needs) Water supply for the myriad of subsurface GW organisms Water for sustainability of GDEs Cultural value through the support for the maintenance of highly adapted GW organisms, a unique part of Europe’s biodiversity GW organisms indicate ecological conditions in GW (e.g. the hydrological and biogeochemical status of the GW system)

2.

3.

4. 5.

2. 3. 4. 5.

6.

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and future generations of humans. The unique organisms living in subsurface habitats are the product of a long evolution and their potential loss is seen as a prejudice to our cultural heritage. This opinion may be in contrast to those of water policy planners who favour socioeconomic criteria (see the recently released GWD).2 Ecological information on GW environments, when compared to the chemical data, is apparently less precise and its inferential power is generally low. This is partly due to the nonlinear processes which dominate organismic activities and occur in many cases also in non-living systems, e.g. karst systems.23 However, considerable research has recently focused on general aspects of ecological theory and praxis, which point out the linkages between biodiversity, ecosystem functioning and services24,25 or which use experimental approaches to quantitatively assess these relationships.26 These concepts can also be applied to the subterranean organisms, which may increase in this way the predictive power of various environmental models. In order to make the argumentation for the necessity to make better use of ecological information for GW management and/or environmental regulations more persuasive we will focus our attention to the following three topics: (1) the GW ecosystem approach, useful for planning environmental policies; (2) the diversity of GW habitats and organisms with their potential interest for environmental monitoring programmes; and (3) GW-dependent ecosystems as constituents of global surface/subsurface environmental units.

11.2.3

The Groundwater Ecosystem Approach as a Framework for Planning Pollution Prevention and/or Environmental Protection Strategies

The European WFD3 only indirectly deals with the ecology of GW ecosystems as it states: ‘‘the status of a body of groundwater may have an impact on the ecological quality of surface waters and terrestrial ecosystems associated with that groundwater body’’. There is an improvement in the new GWD2 as it is mentioned in its introductory presentation the importance of protection measures for GW ecosystems. This requirement was frequently mentioned by ecologists (e.g. Refs. 4–6, 27). It represents an important success of the new regulation and merits to be quoted in extenso: ‘‘Research should be conducted in order to provide better criteria for ensuring groundwater ecosystem quality and protection. Where necessary, the findings obtained should be taken into account when implementing or revising this directive. Such research, as well as dissemination of knowledge, experience and research findings, needs to be encouraged and funded’’.2 However, within the various articles of the GWD (e.g. Articles 1 and 3) only the term ‘‘body of groundwater’’ is mentioned which makes logical reference to the volume of subsurface water, including its quantitative and qualitative aspects. Moreover, Article 1 starts with the emphasis on ‘‘the assessment of good groundwater chemical status’’. Any specialist dealing with various aspects of the subterranean aquatic environment

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knows that the quality and quantity of ‘‘good groundwater’’ depends on the biogeochemical processes in the subsoil, with its connectivity and strength of exchanges between the subsoil system and the surrounding earth layers and with its dependence on the multiple human activities which negatively impact the water. Hence, it becomes inescapable to improve the meaning of the term ‘‘body of groundwater’’ with the scientific content of what we ecologists understand as ‘‘GW ecosystem’’. The interest of this switching of meaning is not a matter of semantics but one of paramount importance for the strategic planning of water policies (a major concern also in the present book!). An ecosystem is generally defined as the integration of various aspects of the physicochemical and biological units which dynamically interplay. Groundwater ecosystems are open subsurface systems through which energy and matter is transferred and further processed. It is delineated by external boundaries that can be recognised as a material reality or can be conceptually defined.28 For open systems (GW systems belong to this type) one has to identify the input and the output areas which allow the contact with the surrounding system. Figure 11.2.1 shows a conceptual model of a GW ecosystem. One can recognise three structural components: (1) the sediment matrix with various types of voids depending on the sediment or rock type (porous, karstic, fractured types); (2) the circulating GW; and (3) the living organisms. The first two units represent the habitat used by the living component of the system. It is to the merit of Castany29 to have pointed out that the major services of GW systems rely on three functions of aquifers: (1) the capacity to store water; (2) to transport with the water through the subsoil energy and matter; (3) to allow chemical and biological changes in water and in the solid substrate. For the third function the biological role of subsurface organisms is of paramount importance, especially that of microbial communities.30 The domain of GW within the earths’ crust is gigantic; metaphorically it can be represented as a ‘‘groundwater arena’’ (Figure 11.2.2). Therefore there is a high diversity of micro- and macro-environments or niches within the subsurface. We know that subsurface water exists in both saturated and unsaturated sediment layers and the water can penetrate deep into the earth down to several thousand metres. Even at more than 1000 m deep GW microorganisms can be detected.31 Exchange activities between surface water and the GW decrease with depth. Figure 11.2.2 depicts schematically the decrease in biological and

Figure 11.2.1

Schematic representation of an ecosystem (from Ref. 28).

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Figure 11.2.2

Chapter 11.2

Conceptual view of the GW domain (see text for details).

chemical activities related to the water circulation and the depth of the subsoil layers. Close to the surface water (shown in Figure 11.2.2 as the white area with undulating lines) matter and organisms penetrate in high concentration and/or number (the surface water is the source of energy and matter penetrating below the soil’s surface); they can be stored there for different periods of time (the subsoil layer acts as ‘‘sink’’ compartment); it can be further released either to the deeper layers or returned to the surface environment. Therefore this superficial GW layer forms a dynamic source–sink ecotone.32 Beneath these zones, GW contains less and less high-value energetic matter, the environment becomes oligotrophic and organisms are strictly specialised to hypogean life (they are called stygobites). This is the domain of GW ecosystems where leaky sink processes dominate. Finally in the very deep layers of GW systems (in porous granular aquifers this should correspond to layers located deeper than several hundred metres below the surface of the soil or in confined aquifers), the GW circulation is very slow, organic matter is scarce and refractory and the aquatic domain is generally hypoxic or anoxic. There is only a minimal return of the water and matter to the surface from this area. One could name this extreme environment metaphorically the zone of the black-hole sinks (an idea of L. Kornicker, personal communication to D.L.D.). Groundwater systems within the sediment layers relevant for human water consumption (in unconfined aquifers this lies, generally, 25–200 m deep below the soil surface) display permanent physical, chemical and biological

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fluctuations, they are far from equilibrium and they can switch when disturbed from one dissipative state to another. The facility with which the systems can return to a previous state marks their resilience capacity. It is well accepted now that GW systems as compared to those of surface waters are more prone to change their ecological state when perturbed by pollutants; also, the resilience time is longer. Hence, it is considered that the vulnerability of many GW ecosystems is greater as compared to surface water systems and therefore GW bodies need better protection measures33 (see Chapter 2.1). Aquifers which are located within landscapes, or hydroscapes, with a huge diversity of both physicochemical and biological attributes have a high capacity to naturally restore their ecological state. Such GW systems display a high functional adaptedness and their quality in terms of providers of ecological services and goods are very much appreciated by water managers.29 Groundwater ecosystems are both objective and subjective entities. It is this dual aspect which causes apparently an insuperable difficulty to water managers. In some cases we can materially define the boundaries of aquifers and we can recognise the input and the output areas.28 In other cases we have to set artificial boundaries especially when we model our system. Groundwater ecosystems as defined above can be investigated at various spatial and temporal scales depending on the interests of scientists or of water managers. A grain of sand with a well-developed assemblage of microorganisms (Figure 11.2.3) covered by pelicular water and a thin layer of organic matter, surrounded by a laminar layer of GW flowing along its surface, already represents a ‘‘minimal’’ GW ecosystem. The granular sandy sediments in slow filtration columns with their biofilms and interstitial meio- and macrofauna represent an artificial small ecosystem which is useful in the laboratory for simulation of various chemical and biological processes which exist in the field but are difficult to observe.28 For GW management purposes one investigates large areas we call aquifers, ‘‘GW bodies’’ or ‘‘subsurface hydroscapes’’. Considering field situations we have to differentiate between deep GW ecosystems where the exchange with the surface water is reduced and superficial

Figure 11.2.3

A ‘‘minimal’’ GW ecosystem: microbial biofilm on a grain of sand (from Ref. 30).

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Figure 11.2.4

Chapter 11.2

The main types of aquifers with their ecotones (from Ref. 32).

systems where the environmental conditions represent a mixture between those dominating the surface waters and those of remote or deep water layers. We call these superficial systems ecotones (Figure 11.2.4) and a whole package of information on their ecology is available.15,34 Porous (granular) aquifers in alluvial sediments along running water systems build within their superficial layers very dynamic ecosystems. Hydrologists and water managers appreciate those systems as they act as ‘‘bank filtration’’ units and produce large volumes of high-quality water for human consumption.35 The habitat is called in the ecological literature ‘‘hyporheal’’ and the organismic assemblages are of ecotonal type. A large number of insect larvae and crustaceans live here beside typical blind hypogean crustaceans. They can locally stimulate microbial activity and change the structure of the sediment through bioturbation processes.36 The dynamics of hyporheic systems are very intensive, closely related to the evolution of surface water fluctuations. Strongly polluted surface water has a negative impact on hyporheic systems, and therefore their degree of vulnerability can increase at fast rates.37 The terrestrial-GW system in porous (granular) sediments is a poorly investigated ecotone. It is common in riparian (wetland) landscapes. Within this transition zone we distinguish both unsaturated and saturated sediments on which rich microbial biofilms, stimulated by the arrival of a large amount of organic matter, may develop. Aquatic interstitial invertebrates like insect larvae or worms which live normally in sediment layers fully saturated with water are also able to colonise

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semi-terrestrial environments (the vadose zone of aquifers).28 Many plants, i.e. the so-called phreatophytes, and meadow trees send their roots into this transitory ecosystem and play an important role in the elimination of nutrients, like nitrates and/or other chemical compounds.38 Groundwater ecosystems in deep aquifers, as mentioned above, have more or less diverse organismic assemblages, their biological activity is reduced and the environmental fluctuations are attenuated. Once such a system is perturbed it needs a longer recovery time. Hence the vulnerability of such systems to anthropogenic pollution is higher than in the shallow ecotonal systems. One should consider the pollution of deeper layers of porous granular aquifers with organic chemicals and thereafter difficulties encountered to restore them back to a pristine quality.39 Finally, one is entitled to ask as to what the best strategy is to protect a porous alluvial aquifer against pollution. The answer depends on the scale at which we need to manage the water resources and on the location within a river basin. Our experience with the ecology of alluvial ecosystems along large rivers like the Danube40 suggests that the most important areas to be protected are the river banks and the river bottom in the areas recognised as major input water zones to the aquifer. The cover land area above the aquifer, and here especially recharge zones and areas where the GW table is close to the surface, have to be better protected against diffused pollution. Karst (ground)water is partly stored in carbonate massifs within large subterranean voids and further circulates through conduits of various diameters, from microcrevices to large tunnels. Precipitation and surface water which infiltrates into the karst systems traverses in many cases a non-saturated superficial layer called epikarst. Further it arrives within the saturated zone and will exfiltrate again through karst springs or karst streams. The aquatic fauna of the epikarst is represented mainly by surface-dwelling organisms; there are few stygobiotic elements. Within the saturated zone of a karst system the water can flow at high velocity through large conduits or can be stored in accessory large voids. The water flows in a coherent way through a whole complex of voids which defines the karst system as a drainage unit.23 The organismic assemblages of karstic systems reflect the hydrological system; the main conduits are traversed by surface-dwelling animals displaying also low abundances in pristine waters. In the annex voids where water is stored and only slowly further released, animal assemblages are well diversified and dominated by stygobiotic species. One can use karstic fauna, especially small crustaceans, like the copepods, as ecological tracers for the identification of the origin of the water41 (see Section 4). The vulnerability of the karst water to pollution events is well known. Good examples are the karst areas in northern Italy and in Austria which have focused attention in the past because of epidemic diseases due to drinking water contaminated with pathogenic microbes. The principle of prevention and protection of karst systems differs partly from those of the porous granular aquifers. One has to identify in the karst, in addition to the zone of infiltration of the water, also the major pathways of

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water travelling through the subterranean systems and the exfiltration points. Polluted water in karst spreads rapidly and can be intercepted by household wells located at the surface of the karst massif, or can be collected at the karstic spring outlets. Therefore the protection strategy is more related to the local mountainous massif and to the pathways of the water circulation as compared to those of porous granular aquifers located within river basins. Finally, it is important to mention here the proposal of de Marsily42 to create ‘‘hydrogeological nature reserves’’, in a similar way that ecologists develop ‘‘natural parks’’ for the protection of valuable landscapes and their ecosystems. Here we advocate the idea of erecting ‘‘nature reserves’’ including both surface and subterranean ecosystems which allow not only the maintenance of pristine GW reserves but also intact assemblages of organisms related to a wide spectrum of habitats.

11.2.4

Diversity of Groundwater Habitats and Organisms: Their Usefulness for Environmental Monitoring Programmes

We mentioned in the previous section that a ‘‘groundwater body’’ has to be viewed as an ecosystem incorporating not only the water but also the sedimentary substrate and the organisms that live within. Therefore for the specialists dealing with GW monitoring it appears necessary to map not only the GW quality but also the characteristics of the subsurface habitats and their living organisms. For instance alluvial sediments along streams not impacted by organic pollution display diverse animal assemblages which develop within different types of habitats.43 The situation can be completely different in chronically polluted sediments, e.g. those which become anoxic over a wide area, and where one finds a monotone type of sediments inhabited by few animal species.44 At the European scale, three major biogeographical regions have to be distinguished for GW fauna, which are mainly the result of the Pleistocene glaciation:45 (1) in those parts of northern and central Europe, which were covered by ice shields, GW diversity within the meio- and macrofauna is low and endemic species are nearly absent; (ii) in western, central and eastern Europe, several endemic and relictual species survived, and regional biodiversity is generally higher than in the north; and (iii) in contrast to these, in southern Europe, where the climate stayed moderate during the various glaciation periods, most of the old Tertiary fauna still persists. These regions are characterised by a diverse endemic, exclusively subterranean dwelling fauna. Here, endemism and diversity are highest in the karstic areas, where evolutionary drift is generally enhanced by the high fragmentation of biotopes. In consequence, more than 50%, sometimes up to 90%, of the hypogean species are strongly restricted in their distribution, with many species recorded from one single site only.46,47

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Considering the microbial biodiversity both cultivation dependent and independent investigations have revealed that microbial communities are dominated by diverse heterotrophic bacteria. Furthermore, modern molecular studies have frequently identified members of several mostly uncultivated lineages as well as phyla totally devoid of cultured representatives.48 An ongoing research project on the ecological assessment of GW ecosystems, funded by the German Federal Environmental Agency, at the Institute for Groundwater Ecology, in Munich, shows that in special cases the subsurface microbial communities are distinct from those found in surface soil and aquatic environments. This distinction becomes apparent at the level of the specific assembly of GW microbial communities and by their special physiological capabilities and/or ecological requirements. Specialised microbial groups, well adapted to the prevailing environmental conditions (e.g. to the availability of electron donors and acceptors) can be used for monitoring GW habitats or for bioremediation programmes.48 During the last few years we have noticed that more and more ecological information on GW habitats and their organisms is used for environmental regulations. For instance the Swiss Water Protection Ordinance not only defines water quality standards, but also ecological goals: ‘‘the biocenosis in groundwater should be in a natural state adapted to the habitat and characteristic of water that is not or only slightly polluted’’.49,50 A GW environmental assessment system requires per definition the identification of the ‘‘pristine reference status’’ of GW bodies (as habitats). Additionally the organismic communities can be used as biological indicators. For instance based on the hydrological exchange and the availability of organic matter and oxygen at a subsurface site, Hahn51 described three types of GW habitats with specific animal communities. These types are called (1) oligo-alimonic, i.e. ones with poor supply of organic matter (OM) resulting in an extremely poor fauna (mainly stygobiotic); (ii) meso-alimonic, i.e. ones with medium OM supply supporting an abundant and diverse stygobiotic fauna; and (3) eu-alimonic assemblages, i.e. ones with a high OM supply resulting in a very abundant and diverse fauna, but in this case dominated by surface-dwelling fauna (stygoxenes) and ubiquitous species. There are also examples for a complete community shift from a stygobiotic (exclusively subterranean dwelling organisms) to stygoxenic fauna (surface-dwelling organisms colonising temporarily the subsurface habitats) resulting from organic pollution.52–54 Metazoan fauna nicely reflect structural conditions such as hydraulic conductivity, heterogeneity of habitats in an aquifer and/or provide information on surface/subsurface hydrological exchanges. The composition of the meio- and macrofauna can further be used in many cases as an indicator for organic pollution. Hence this type of information can be used as an early warning system for the environmental quality of areas were drinking water production plants are located or may be considered in licensing procedures for water extraction or the evaluation of wetlands.27,54–56,71,72 Due to their omnipresent distribution, microorganisms and microbial communities may represent an attractive target for biological assessments,57,58 and may serve as reliable bioindicators for GW ecosystems.50,59,60 Microbes are characterised by short generation times and comparably high metabolic rates

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providing a fast reaction to changes in environmental conditions, mainly reflected by changes in their activity and shifts in the community composition. Today, these effects may be resolved by means of cultivation-independent molecular methods. Based on the central hypothesis that in low energetic habitats with stable environmental conditions (such as most GW ecosystems) the microbial communities nicely reflect the in situ environmental conditions, the composition of microbial communities and their physiological status can serve as (bio)indicators for the assessment of the ecological situation. Molecular fingerprinting techniques used in microbial community analysis of GW offer information on changes in the community composition, which are related to environmental conditions including anthropogenic pollution. As an example RNA/DNA sequence analysis may deliver information on the individual members of the microbial community from which environmental conditions can be deduced. The analysis of functional genes on DNA bases reveals the potential for individual processes within communities and groups. Comparative analysis of microbial communities (bacteria, archaea, protozoa and fungi) in pristine and anthropogenically impacted GW ecosystems will, in the near future, provide the foundation for the selection of microbial species or groups indicative for a ‘‘healthy’’ and/or ‘‘impacted’’ status.50,59,60 A selection of valuable bioindicators will subsequently be collected and with the help of modern molecular tools, such as DNA microarray techniques, easy-to-handle assessment tools may be developed.58 Another important aspect of GW monitoring schemes is related to the artificial recharge of aquifer in urban zones. It is known that the increased demand for water in cities has motivated the search for replenishment of GW reserves through artificial recharge of the aquifers. Urban GW is commonly recharged by rivers, lakes and storm water runoff.61 Monitoring the quality and quantity of the water in urban sectors is a complex activity because it needs to observe many different parameters. Therefore new observation facilities were installed. The French Field Observatory in Urban Hydrology (OTHU), for instance, has offered an integrated research programme since 1999. Its longterm objective is to acquire reliable data on urban effluents during rainfalls and their impact on surface water and GW. An important activity of the OTHU is to monitor the impact of artificial storm water infiltration on GW ecosystems.62 Present data show that storm water infiltration leads to an increase of the local subsurface water temperature, of the OM content and of various other chemical nutrients.63,64 The OM enrichment of GW was positively linked to the density and diversity of GW assemblages of microorganisms and of invertebrates. Hence, the biotic subterranean communities represent useful biological indicators for urban GW quality. With this knowledge, and methodologies, it is possible to assess the sustainability of GW demand in the area of Lyon. Moreover it helps specialists dealing with urban water policies.62 In conclusion, we should point out here that the development of a biological assessment system within environmental programmes is not intended to replace traditional hydrological and physicochemical standard protocols, but rather to complement them.

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11.2.5

683

Groundwater-dependent Ecosystems: A Holistic Representation

Groundwater-dependent ecosystems (GDEs) are hydroscapes or landscapes that must have access to GW in order to maintain their ecological structure and function.65 The implementation of the WFD3 requires the provision of an adequate amount of water for the individual ecosystem types. In trying to adapt an integrated river basin management (IRBM) concept as envisaged by the WFD, in most cases much attention is given to the maintenance of riparian and instream habitats. In many instances it has been the principal concern of water allocations under environmental flow considerations. Here, the sum of estimated environmental flows over a year is the total annual water volume, which can be allocated for environmental purposes.66 However, providing water for the environment is more than mere allocation of GW to river flow and riparian health. The assessment of environment flow requirements at river basin scale becomes more complex especially if all downstream fluvial and coastal requirements have to be considered.67,68,69 The following are some examples:  arid and semi-arid regions, such as in Mediterranean countries (Greece, Italy, Spain), which are characterised by long dry periods interrupted by short periods of high rainfall intensities and where running waters are most of the year driven by baseflow, i.e. the portion of streamflow that is contributed by GW;  wetlands depending on GW influx at all times of the year;  terrestrial ecosystems that show seasonal or episodic reliance on GW; and  estuarine and near-shore marine ecosystems that use GW discharge. The impact of the exploitation of GW resources on GDEs is a major concern for water supply companies70 as the proportion of GW in drinking water is generally high in Europe1 and one of the best places to extract huge volumes of subsurface water for human needs are the riverine aquifers. In view of these important economic aspects of GDEs, new research should be developed in the future combining ecology with hydrological studies,16 and/or using Castany’s concept of the ‘‘global aquifer/river system’’.29 So finally, if GW policy and management systems intend to appropriately consider and protect GDEs a better understanding will be needed of (1) identification of likely GDEs and assessment of the nature of the dependency, (2) analysis of the respective ecosystem dependency on GW and timing of the dependency, (3) GW regime required to meet the water requirements of the ecosystem and (4) the impacts of change in key GW attributes on that ecosystem. By providing water managers and policy-makers with recommendations to the above, scientists can help managers to understand what will be required for sustainable management of GDEs and to integrate them in their plans.

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Chapter 11.2

Overview: The Expanded Order (Achievements and Future Needs)

The information presented here should convince the reader that GW is not only an important resource needed for the well-being of humans but also a living medium for the diversified forms of life below the surface soil; it fuels water and energy to various kinds of subsurface, and even surface ecosystems. The multifarious activity of subterranean organisms offers valuable (but mostly unrecognised) services to nature and humans. Hence, we are sure that GW ecology is a new important aspect in modern GW research. However, we still need to develop new pathways for the communication between the various partners involved in GW science. Once this important initial step is achieved we have to further transmit our combined GW knowledge to a broad spectrum of interested parties. Beside laypersons, stakeholders, water managers, providers for research and technology development as well as the policy decision-makers need to be informed about the advancement in GW ecological research. Figure 11.2.5 portrays this idea, inspired from Ref. 11 and from Chapter 2.1. Within this ‘‘expanded order’’, it is important to offer some hints about what ecology in the future may offer for improved management and protection of the GW domain. 1. Groundwater ecology is a useful tool for water management. Stakeholders, operational managers and policy-makers will profit from the use of ecological knowledge and from the experience of GW ecologists. 2. GW ecology should contribute to programmes which unify the problems of resource sustainability with those of the maintenance of GW ecosystem integrity.

Figure 11.2.5

Flowchart of the way scientific knowledge is communicated to laypersons, water managers and policy-makers (from Ref. 12).

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3. GW organisms are especially important for the self-purification processes of GW systems; hence the maintenance of a healthy diversity of organisms is extremely important. We need early warning and ‘‘alarm bell’’ technologies which are able to rapidly detect pollution threats or trends in GW ecosystem stress. Micro- and/or macrobiota may selectively be used as indicator organisms for giving more complete information about the qualitative state of GW ecosystems. However, the diversity of these organisms should be first better mapped, bioindicators identified and subsequently tested for monitoring purposes. The same applies for the habitats in which the GW organisms live. The EC 7th Framework Research Programme can provide a good basis for the development of such new technologies in ecological monitoring. 4. The project PASCALIS (funded within the EC 6th Framework Research Programme)10 offers important recommendations for the way we should protect the aquatic subterranean biodiversity and how we should use the diverse organisms for water management and for protection policies. It is proposed inter alia: (a) the establishment of priority lists of GW animal species and GW habitats (aquifers) to be protected; (b) the application of biodiversity data to the evaluation of the ecological status of GW bodies; and (c) the development of a European network of nature reserves for the GW domain, which will protect not only the quality and quantity of subsurface water but also diverse subterranean organismic assemblages. 5. An interesting aspect of the new GWD is the flexibility offered to the EU member states for deciding on the practical measures for monitoring and/ or protection of the GW environment. Hence, member states could independently, where possible or useful, integrate GW ecology in their water policies. Especially the Mediterranean countries (e.g. Italy, Spain, Greece, Portugal) with their chronic problems of water shortage and economic problems to fund environmental monitoring schemes could profit from existing GW ecological knowledge. 6. The WFD and the GWD will have to account for the large differences between karstic and porous granular aquifers (e.g. self-purification potential, water residence time, vulnerability). Hence, one needs different strategies for their management and protection. 7. GW ecology should be horizontally linked with other strategic EU frameworks and directives (like Natura 2000, the Birds and Habitats Directive or the Thematic Soil Strategy). 8. We have to raise more public awareness on the ecology of subterranean waters and its importance for both humans and nature. Hence, it will be necessary to undertake systematic campaigns highlighting the ‘‘yet unrecognised’’ and positive contribution of the GW ecosystem services within the broad umbrella of the advantages offered by GW science. 9. Finally, by incorporating ecology in the policies dealing with water management we insert positive values of nature besides the existing socioeconomic values, those dealing with the quantity and quality aspects of the water. Our efforts to communicate these ideas to a broad spectrum

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of people, if accepted and further developed, should enrich GW science and in the long term improve the economics of GW resources.

Acknowledgements Professor Ph. Quevauviller is acknowledged for the productive exchange of ideas concerning our topic and for his support and patience during the preparation of this contribution. One of us (D.L.D.) acknowledges the Austrian Foundation for Research (FWF) which gave financial support during the years of his groundwater ecology research. Many colleagues helped with information and logistical support, a few are here mentioned, M. Bakalowicz, L. Kornicker, T. Lu¨ders, A. Mangin, R. Rouch, F. Schiemer, C. Schweer, K. Minati, J. Knoblechner, M. Pichler and H. Ployer, who helped during the production of the manuscript. J.G. and F.M-B. acknowledge the Urban Community of Lyon and the Rhoˆne-Alpes Region for their financial support of the OTHU projects for many years. C.G. is indebted for financial support to the Helmholz Society, to the German Ministry of Education and Research (BMF, contract KORA 02 0462) and to the German Research Foundation (DFG, contract ME-2049/2-1) and the Federal Environmental Agency (UBA project ‘‘Biological assessment of groundwater ecosystems’’).

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