Assessing the ecological status of the “artificially intermittent” Evrotas River (Greece) according to the Water

Framework Directive 2000/60/EC.

Leonidas Vardakas, Nikolaos Skoulikidis, Ioannis Karaouzas, Konstantinos Gritzalis, Vassilis Tachos, Stamatis Zogaris, Dimitris Kommatas & Alcibiades Economou

Hellenic Centre of Marine Research - Institute of Inland Waters Athens, GREECE

Abstract The Water Framework Directive (WFD) 2000/60/EC requires establishing ecological status classification techniques, through the use of quality elements (hydromorphological, chemical-physicochemical and biological).The WFD dictates that the elements to be selected must be those that present sensitivity to the prevailing anthropogenic pressures. In the framework of a Life-Environment research project (2006-2008), we undertook the task of developing and applying techniques to assess the ecological status of Evrotas River basin, using hydromorphological, physicochemical and biological (fish and macroinvertebrate fauna) quality elements. However, the research coincided with a severe drought event, which was combined with water resources overexploitation and resulted to the dessication of almost 80% of the main river course.The scope of the study was to compare data of ecological status assessment through the use of the four applied techniques. Our results indicate that the physicochemical and macroinvertebrate quality elements can provide reliable results on the pollution impacts of Evrotas River basin. In contrast, fish were found to be more sensitive to hydrological pressures and had a more lasting contribution to assessment. Finally, we assessed the overall ecological status of the basin by applying the “one out- all out” principle. Overall, the assessment techniques applied, when combined, can provide an integrated assessment of the ecological status of an artificially intermittent river. The results from this study may assist specific measures to be implemented within the Integrated River Basin Management Plan of Evrotas River Basin in order to restore environmental conditions and achieve a good ecological status for the entire drainage. Keywords: Water Framework Directive; Ecological quality; intermittent rivers; chemical-physicochemical; hydromorphological; fish; macroinvertebrates Introduction

In order to cover human needs, without affecting the environmental integrity of freshwater ecosystems, intergrated water management plans have become necessary. Towards this direction, the implementation of the Water Framework Directive (WFD) 2000/60/EC by the European Council in December 2000, launched an innovation in the European’s Union (EU) policy concerning water resources management. The WFD introduced for the first time the assessment of the quality of all surface water bodies (lentic and lotic surface waters, transitional and coastal waters) the term “ecological status”; which is defined as the ecological integrity of an aquatic ecosystem based on biological, hydromorphological and physicochemical elements. The WFD defines guidelines to preserve good ecological status and restore degraded water bodies in Member States. One of the basic objectives of the WFD is the classification of water bodies into five categories of ecological status (high, good, moderate, poor, and bad). The overall aim of the WFD is to achieve ‘‘good ecological status’’ and ‘‘good water chemical status’’ in surface water bodies by 2015. Even though the WFD includes a wide range of water bodies, intermittent rivers and especially artificially intermittent rivers are not particularly addressed within the directive. Intermittent rivers and streams dominate surface runoff in large parts of Mediterranean countries which are characterised by seasonally semi-arid climatic conditions (Estrela et al., 1996). They are of significant economic and ecological importance, since they play a pivotal role for both public and agricultural water supply and ecosystem preservation. Temporary running waters are extremely sensitive to hydrological pressures (e.g. direct water abstraction, groundwater exploitation), pollution, and changes in catchment land use. Nevertheless, monitoring and research mainly focus on perennial rivers, whereas temporary running waters

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have been generally neglected (tempQsim Consortium, 2006). However, in view of water scarcity and the potential effects of climate change, there is a need to include temporary water bodies in river basin management plans compliant to the demands of the WFD. Despite the fact that flow regime alteration constitutes the most serious threat to ecological sustainability of river ecosystems, we are still lacking trustworthy scientific tools for assessing the ecological status of intermittent rivers and streams. In the framework of a Life-Environment research project (2006-2008), we developed and applied techniques to assess the ecological status of Evrotas River basin, using hydromorphological, physicochemical and biological (fish and macroinvertebrate fauna) quality elements. The Evrotas River presents the characteristics of a typical Mediterranean stream system, with low-flow during summer and high-flow during winter season. One of the river’s main features is that some portions have no surface-water flows during the dry period of the year. However, this intermittent character of much of the river’s main-stem was not a normal feature of the river in historical times, it has become an attribute of the present-day river environment, after modern anthropogenic degradation (Skoulikidis et al., 2009). This study aims to compare data of ecological status in an artificially intermittent river through the use of four assessment techniques applied according to the demands of the WFD. Study area

Evrotas River basin is located in the southernmost part of the Balkan Peninsula, in south-eastern Greece (Peloponnese). The catchment of Evrotas covers a total area of 2,418 km2, and discharges into the Laconicos Gulf. The basin has a typical Mediterranean climate with mild and cold winters and prolonged hot and dry summers with an average annual temperature of 16ºC and a mean annual precipitation of 803 mm (for the period 2000-08). A characteristic of the Evrotas R. is the presence of springs along the river channel route. The vast majority of the river basin is covered by natural and semi-natural areas accounting for 61% of the total river basin, followed by agricultural areas that cover 38%, while urban areas account for 1%. The dominant pressures in Evrotas basin derive mainly from agricultural activities and include overexploitation of water resources for irrigation, disposal of agro-industrial wastes, agrochemical pollution and significant hydromorphological modifications. Only one Waste Water Treatment Plant (WWTP) exists in the basin (city of Sparta), while villages are served by private permeable and impermeable cesspools. From an ecological point of view, the Evrotas basin can be characterized as a unique biodiversity hotspot in Greece, including many local endemic plants and vertebrates. This high proportion of endemicity is attributed to the complex geological and climatic history of the area which, combined with geographical isolation and environmental diversification, have provided conditions conducive to speciation. The river accommodates five native freshwater fish species and two that have been introduced. Three of the native species are range-restricted endemics of outstanding conservation value: Squalius keadicus (Stephanidis, 1971) and Pelasgus laconicus (Kottelat & Barbieri, 2004), which are confined exclusively to this river, and Tropidophoxinelus spartiaticus (Schmidt-Ries, 1943), which also occurs in some rivers of southern Peloponnese. The native fish fauna also includes the species Anguilla anguilla (eel) and the perimediterranean Salaria fluviatilis (Asso, 1801), while a few marine species also enter the lowest portions of the river also (e.g. mugilidae).

Methodology

Sampling network

Figure 1 presents the sampling network. 43 stations were established along the Evrotas main course and the majority of its tributaries for monitoring hydromorphological, physico-chemical and biological (macroinvertebrates) quality elements. Sampling was conducted at three seasonal periods (May 2006, September 2006, March 2007). For the ichthyological investigation 66 stations were selected mainly along the Evrotas main stem and along the Oinous tributary and sampled during six campaigns at high and low flow periods (spring and summer) in the years 2006-2008.

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 Figure 1. The Evrotas River basin, with sampling stations and the areas designated as core areas for fish conservation ( fish sampling sites, macroinvertebrates, hydromorphological and physicochemical sites). Status assessment techniques and procedures

The ecological status of Evrotas River was assessed through the use of four quality elements: a) Hydromophological, b) chemical-physicochemical c) macroinvertebrates and d) ichthyofauna. The hydromorphological status assessment was based on the River Habitat Survey (RHS) method (Raven et al., 1997). This method was performed at a 500 m length of each site, during the summer of 2006. The RHS method assesses the natural character and quality of river habitats based on two metric systems, the Habitat Quality Assessment (HQA) and the degree of habitat modification (Habitat Modification Sore, HMS). The HQA assesses the quality of habitat in terms of its diversity. The HMS assesses the degree of river degradation. For the HMS classification, the six initial HMS categories were merged into five. For the assessment of the chemical-physicochemical status, water temperature, pH, conductivity, dissolved oxygen current velocity and the wetted transect were measured in-situ at each stream site. Water samples were collected, preserved in cool conditions (4ºC), filtered upon arrival in the laboratory through 0.45 μm membrane filters and analysed for major ions, silicate and nutrients (nitrate, nitrite, ammonia, total nitrogen, phosphate and total phosphorous). Sediment samples were analysed for major elements, heavy metals, total and organic carbon, total nitrogen, organic and inorganic phosphorous. In selected sites, pesticide residues were determined in water and sediments.The classification of the chemical-physicochemical status was carried out, using water and sediment attributes, according to the guidelines of Guidance Document No 13 of the WFD and Skoulikidis (2008) and by averaging the results of the seasonal samplings. The quality scores of individual chemical-

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physicochemical quality parameters (e.g. dissolved oxygen, nutrients, heavy metals) were achieved by comparing their levels with existing quality standards (Cardoso et al., 2001; Skoulikidis et al., 2006; Skoulikidis, 2008). Two groups of chemical-physicochemical quality parameters, related to particular types of pressures, were identified: a) dissolved oxygen, ammonia, nitrite, that represent “organic pollution” and b) nitrate, phosphate, heavy metals and pesticides (when available), that indicate “chemical pollution”. The status of each group of parameters was carried out by averaging the quality scores of the individual parameters. Finally, the chemical-physicochemical status of each site was derived by the results of the group of parameters that indicated the greater impact. Benthic macroinvertebrates sampling was conducted with the STAR-AQEM sampling methodology (AQEM Consortium, 2002). To assess and classify the biological status using macroinvertebrates, the following procedure was performed: a) typological classification and establishment of type specific reference conditions according to the Intercalibration Exercise (EC, 2007), and b) assessment and classification of biological status using the STAR_ICMi multimetric index (Buffagni et al., 2007). The final classification of benthic invertebrate status was performed by averaging the results of seasonal data. Ichthyological sampling was conducted by electrofishing using standardised methods as developed in the EU FAME project (2005). For the assessment and classification of the biological status of the river using fish fauna, a multimetric index was developed specific for Evrotas River basin (Skoulikidis et al., 2009). The development of the fish-based index included the following steps: a) designation of biotic types (river typology) using fish-assemblage cluster analysis, b) establishing type-specific reference conditions by utilizing historical data, descriptive statistics of fish assemblages, and natural history base-lines (expert judgment), c) identification of appropriate metrics (ichthyological attributes that are known to respond to anthropogenic pressures) for each biotic river type, and d) the initial application and calibration of the type-specific metrics within the multimetric index. Site classification into five classes of ecological status was based on the definitions of the Guidance Documents No. 10 (2003) and No. 13 (2005). Briefly, hydromorphological quality elements were taken into account when assigning sites to high ecological status, physico-chemical quality elements were considered when assigning sites to high and good status and biological quality elements when assigning sites to any of the ecological status classes. For the integrated assessment to derive the final ecological status, the “one out all out” principle was applied. Designation of water bodies

In accordance to the Guidance Document No 2 (2003), the initial designation of water bodies was based on geographical (river segment physiography) and hydrological determinants (such as hydromorphological surface-water features). Subsequently, the ecological quality of sampling site(s) was taken into account and in cases where sampling sites were missing the water bodies were delineated and defined based on anthropogenic pressures and local information (expert judgment). In particular, water bodies in the main stem of Evrotas R. were defined based on geographical and hydrological factors, the biological status of fish fauna and on hydro-morphological pressures. In the tributaries the designation of water bodies was based on an abiotic classification (average altitude, geology and site’s catchment area). Geological types (carbonate, siliceous, clastic sediments) were distinguished according to hydrogeological characteristics. Reaches of tributaries belonging to distinct types were separated to additional water bodies considering a) a change in the ecological status along the tributary (in case of existence of more than one sampling sites) and b) the distribution of significant pressures (particularly point source pollution and hydromorphological alterations). Results and Discussion Hydromorphological status

Expansion of farmlands towards the river banks, flood control works such as straightening and embankment of river courses and extraction of inert materials from the river bed have caused significant hydromorphological modifications in the Evrotas river network. Large portions of the river course mainly near the city of Sparta and at the river mouth have been

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regulated and straightened and riparian forests have been vanished and replaced by agricultural lands. The RHS results indicated that the Evrotas River basin presents a great range of hydromorphological alterations and in several cases the river is significantly modified. Half of the examined sites scored below good status. Only sites located in medium and high altitudes, as well as in remote areas of the river were found to be undisturbed or slightly modified (Figure 2).

Hydromorphological status

26%

24%21%

19%

10%

Chemical-physicochemical status

12%

72%

16%

Biological statusMacroinvertabrates

36%

32%

21%

8% 3%

Biological statusFish

21%

26%

53%

HighGood Moderate

PoorBad

Hydromorphological status

26%

24%21%

19%

10%

Chemical-physicochemical status

12%

72%

16%

Biological statusMacroinvertabrates

36%

32%

21%

8% 3%

Biological statusFish

21%

26%

53%

HighGood Moderate

PoorBad

Figure 2. The hydromorphological, chemical-physicochemical and biological status (macroinvertebrate fauna and fish) of Evrotas River Basin for the period 2006-2007. Physico-chemical status

The chemical-physicochemical status of Evrotas River Basin ranged between high and moderate, whereas the vast majority of the examined stations (84%) score good and high (Figure 2 & 3). Only seven sites scored moderate due to high organic and chemical impact, resulting from point and disperse pollution sources, such as the WWTP of the city of Sparta, fruit juice factories, olive oil mills, slaughterhouses, agrochemicals, etc. The applied physico-chemical assessment and classification system provides the following advantages: a) the distinction of chemical pollution parameters into groups (following the Guidance Document No 13) results to a better representative classification of the chemical-physicochemical status (the “one out all out” principle may lead to an underestimation of the physico-chemical status, whereas averaging the whole set of parameters may lead to an overestimation of the chemical-physicochemical status), b) the inclusion of sediment quality elements, which is recommended by other authors and European networks (e.g. Quevauviller, 2006; SedNet, 2004), since sediments better response to past pollution events than water, and c) the integration of toxic substances (heavy metals, and, partly, pesticides) although respective point sources were missing. This was prescribed by the presence of extensive diffuse sources of pollution. A weakness of the applied system is that certain parameters, such as ΒΟD5, phenols and pesticides (in the majority of the sampling network), have not been examined. If these parameters were integrated in the assessment system, possibly the quality of this group, and consequently the final chemical-physicochemical status, would have been termed worse. Biological status (macroinvertebrate fauna)

The biological status based on macroinvertebrate communities showed high spatial and temporal variability depending on the distribution of point pollution sources. In the majority of the assessed sites (68%), the biological status scored between high and good (Figure 2 &

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3). Reference sites were mainly confined to the upland parts of the tributaries of the Parnon and Taygetos mountains, while sites classified as slightly undisturbed (good status), were located mostly at semi-mountainous and lowland areas with no significant agricultural activities. Moderate sites were mainly affected by urban wastes and olive mill wastewaters while the sites classified as poor and bad were affected by fruit juice processing wastewaters and pesticides. It should be mentioned, that sites which were dry in summer 2007 were not classified bad (as in the case of fish) since macroinvertebrate communities seem to recover during the next rainy season (Skoulikidis et al., in prep). It should be mentioned that for a number of sites receiving olive mill wastewaters, the resulting ecological status seems to be overestimated (i.e. good status), since the winter sampling campaign did not coincide with the operation of olive oil refineries, as initially designed. This was attributed to the fact that in 2007 olive oil refineries stopped processing earlier than usual, due to the low harvest of that year. As a result, riverine ecosystems had partially or completely recovered before our sampling survey.

Figure 3. Chemical–physicochemical status (right) and biological status based on macroinvertebrates (left) of Evrotas River Basin, during the period 2006-2007. Biological status (ichthyofauna)

The application of the fish based index for the year 2007 revealed widespread degradation of the fish communities. More than half of the sites examined (53%) were classified as bad (Figure 2 & 4). This situation was attributed largely to the unusual prolonged drought event, which occurred in the summer of 2007 and, combined with water resources overexploitation, resulted to the drying of almost 80% of the main river course. In the remaining part of the river, where summer flow was maintained, the biological status based on fish fauna ranged between high and moderate. The biological status was not improved in the year 2008, which was a hydrological normal year. The persistence of the generally poor biological status in 2008 was attributed to the slow rate of re-establishment of fish communities in previously hydrological disturbed areas, given that fish a) are wholly water-dependent organisms that require ‘‘water bridges’’ for their migration, and b) have longer life-spans and later age at maturity than most other aquatic organisms. Effectively, fish-based ecological assessments can reveal “remaining effects” of past hydromorphological disturbances and can be successfully implemented to trace long-term human impacts on the ecosystems. The vast majority of Evrotas tributaries dry-out under human pressures and fish communities are either missing or strongly disturbed. If fish have been included in the assessment system of these tributaries, their ecological status would be classified, according to expert judgment, as poor or bad. It becomes apparent that the main environmental problem of the Evrotas River is the immense and uncontrolled water abstraction. The latter, in combination with the unusual drought in 2007-08, resulted in the desiccation of the vast majority of the river network, which caused massive fish mortality in isolated reaches that maintained water (i.e. in

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remaining pools). If the current water exploitation continues, it is probable that unique endangered species may become extinct .

Figure 4. The biological status based on fish fauna for the years 2007 and 2008 (with ▲ are symbolized sites where the index did not responded to the existing pressures). Water bodies of Evrotas River Basin

Figure 5 presents the designated water bodies in Evrotas main stem, and Figure 6 presents the classification system applied to identify the water bodies in Evrotas tributaries. Overall, seven water bodies were designated for the main course of Evrotas River and thirty seven for its tributaries.

Figure 5. Water bodies in the main course of Evrotas River.

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Upland LowlandSemi-mountainous

Silicate Carbonate

10-100Km2 >100Km2

Silicate Carbonate Sediments Sediments

10-100Km2 >100Km2

3 9 4 4 4 12 1

Upland LowlandSemi-mountainous

Silicate Carbonate

10-100Km2 >100Km2

Silicate Carbonate Sediments Sediments

10-100Km2 >100Km2

3 9 4 4 4 12 1

Figure 6. Classification of water bodies in Evrotas tributaries (in boxes number of water

bodies). Ecological status of water bodies

Figure 7 presents the final ecological status of the examined water bodies in Evrotas River Basin. Water bodies of tributaries that presented lower than good ecological status were mainly affected by point sources of pollution. The main portion of the Evrotas main course presents lower than good status due to artificial desiccation. It should be mentioned that few decades ago all fish species inhabiting Evrotas were widely distributed throughout the river and its tributaries. Due to human interventions (overexploitation of surface and ground water resources), the majority of Evrotas tributaries are presently either “fishless” or contain heavily disturbed fish assemblages. Thus, the icthyological research was mainly conducted along the river’s main stem. If fish have been included in the assessment system of the river’s tributaries, their ecological status would have been classified poor or bad.

Figure 7. Final ecological status in Evrotas water bodies.

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Conclusions

The main environmental problem of the Evrotas River basin is the immense and uncontrolled water abstractions, and this is compounded by morphological modifications and point and disperse sources of pollution.

Chemical-physicochemical quality elements and macroinvertebrates were found to be appropriate quality elements for assessing pollution impacts on the riverine ecosystem. Point and disperse pollution sources (locally and temporarily) deteriorate the chemical-physicochemical and biological status (ranging between moderate and bad) of sites downstream fruit juice factories, olive mills, and the WWTP.

The Ichtyofauna proved to be suitable for assessing hydrological and morphological alterations. Along the main course of the Evrotas the biological status determined by fish fauna presented the worst status assessement, relative to the other quality elements used for assessment.

Overall, the assessment techniques applied, when combined, can provide an integrated assessment of the ecological status of an intermittent river.

The over-exploitation of Evrotas River water resources and the pollution originated from agricultural activities have created ecological implications that must be taken under consideration within a strategic conservation planning framework. The development of integrated water resources management planning is a complicated and multidisciplinary process and must involve the implementation of specific restoration measures as soon as possible. This study identified the dominant pressures and assessed the impacts on the ecological integrity of the river. The results from this study may assist in adopting specific restoration measures to be implemented within the Integrated River Basin Management Plan of Evrotas River Basin in order to improve environmental conditions for the entire drainage.

Acknowledgements Data for this study were derived from the LIFE-EnviFriendly Project (LIFE05 ENV/GR/000245): “ENVIRONMENTAL FRIENDLY TECHNOLOGIES FOR RURAL DEVELOPMENT” (www.envifriendly.tuc.gr). Additional data were collected in the framework of the MIRAGE (Mediterranean Intermittent River Management, www.mirage-project.eu) Project. We would like to express our gratitude to Vasilis Papadoulakis (DLR), who provided hydro-meteorological and hydrochemical time series and to Andriopoulou A., Koutsodimou M., Bertahas I., Laschou S., Kouvarda T., Amaxidis G., Economou E., Koutsikos N., and G. Chatzinikolaou for their assistance in field work and laboratory analyses. References

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