The environmental state of rivers in the Balkans--a review within the DPSIR framework

Reduced greenhouse gas emissions from particulate organic matter degradation in iron-enriched sediments

Iron (Fe) plays an important role in the biogeochemical cycling of carbon and nutrients in aquatic systems. Reactive Fe phases can interact with organic carbon and facilitate the removal of carbon from the biogeochemical cycle; however, this important ecosystem function is often strongly controlled by Fe availability. Due to pollution from lignite mining in the Lusatian province in Northeast Germany, large amounts of iron and sulfate are released into the fluvial-lacustrine system of the Spree River. It was hypothesized that the input of freshly precipitated iron oxyhydroxides from mining areas (e.g., ferrihydrite) alter the biodegradation of particulate organic matter (POM) in downstream lacustrine sediments. To investigate the Fe-dependent degradation of POM, slurries mimicking iron-polluted sediments (85 mg Fe per g, 116 mg Fe per g, and 149 mg Fe per g dry weight) were incubated with plankton or leaf POM under anoxic and oxic headspace conditions, and CO2 and CH4 emissions, water chemistry, and stable isotopes of dissolved inorganic carbon were measured. The experiments revealed that (i) with an increasing Fe content, the CO2 and CH4 emissions were gradually reduced, (ii) CO2 and CH4 production was higher during plankton degradation than during leaf decomposition, and (iii) under oxic conditions, CO2 production was higher and CH4 production was lower when compared to the treatments under anoxic conditions. These findings demonstrate that while benthic mineralization of fresh POM typically releases greenhouse gases into the water column, the availability of iron oxyhydroxides can contribute to reduced greenhouse gas emissions from sediments. This is of considerable relevance for future carbon budgets of similar mining-affected, iron-polluted fluvial-lacustrine river systems.

Study on the Spatiotemporal Evolution and Driving Factors of Ecological Security in Stages Based on the DPSIRM-SBM Model: A Case Study of the Yangtze River Economic Belt

Scientific assessment of urban ecological security (ES) is an important prerequisite to realize regional sustainable development. Previous studies lack the consideration of quality and poor systematic correlation, which could not reflect the internal dynamic relationship. On the basis of considering the time lag, this study divided the research process into the natural operation stage and the management feedback stage based on the driving forces, pressures, state, impacts, responses, management (DPSIRM) framework model and DEA theory, so as to effectively overcome the above shortcomings. Finally, we analyzed the spatio-temporal characteristics and influencing factors of the ES level of 108 cities in the Yangtze River Economic Belt (YREB) during 2005-2019. The results showed that: (a) both two stages showed a slow and fluctuating upward trend in time series, and the level of urban ES in the management feedback stage was significantly higher than that in the natural operation stage; (b) with the passage of time, the spatial distribution of ES in the natural operation stage gradually developed towards the middle and downstream of the YREB, while the management feedback stage mainly evolved from the midstream to the edge area; (c) the level of urban ES presented a different degree of spatial agglomeration phenomenon, and showed an increasing trend over time; and (d) the key influencing factors gradually changed from pressure to response during 2005-2019. This research aims to provide an innovative perspective for the measurement of urban ES, and provide scientific reference for improving urban ecological sustainable development.

Ecological risk assessment under the PSR framework and its application to shallow urban lakes

Shallow urban lakes are naturally vulnerable to ecosystem degradation. Rapid urbanization in recent decades has led to a variety of aquatic problems such as eutrophication, algal blooms, and biodiversity loss, increasing the risk to lake-wide ecological sustainability. Instead of a simple binary assessment of ecological risk, holistic evaluation frameworks that consider multiple stressors and receptors can provide a more comprehensive assessment of overall ecological risk. In this study, we analyzed a combined dataset of government statistics, remote sensing images, and 1 year of field measurements to develop an index system for urban lake ecological risk assessment based on the pressure-state-response (PSR) framework. We used the developed ecological safety index (ESI) system to evaluate the ecological risk for three urban lakes in Jiangsu Province, China: Lake Yangcheng-LYC, Lake Changdang-LCD, and Lake Tashan-LTS. LYC and LTS were classified as "mostly safe" and "generally recognized as safe," respectively, while LCD was assessed as having "potential ecological risk." Our data suggest that socioeconomic pressure and aquatic health are the two main factors affecting the ecological risk in both LYC and LCD. The ecological risk of LTS could be improved more effectively if regional management plans are well implemented. Our study highlights the pressure of external wastewater loading, low forest-grassland coverage, and lake shoreline damage on the three selected urban lakes. The findings of this study can inform watershed management for lake ecosystem restoration and environmental sustainability.

Letter to the Editor

A paper recently published entitled "Water crisis in Iran: A system dynamics approach on water, energy, food, land, and climate (WEFLC) nexus" (Barati et al., 2023). In the mentioned study, a WEFLC model is developed to analyze the water scarcity in Iran. Water crisis, as a complex and challenging issue, has different interdependencies in the context of socio-ecological systems (SES), making it an incorrigible issue. The original paper attempted to assess the water resource dynamics through a systemic lens and explore the impact of various driving forces of water resource planning and management on the water crisis. Iran is a well-studied country, especially around water-related problems. Many interesting facts and findings through the water scarcity analysis in the context of WEFLC are mentioned in the original paper. For instance, it is highlighted that "Mitigation and adaptation policies must be system-oriented and coherent at sectors." However, the original paper did not benefit enough from the previous studies and the full potential of available data. Moreover, some arguments contradict previous findings and, in some cases, are logically flawed. The original paper barely alludes to the nonlinear functional relationships among the components of WEFLC, the core expected component in complex system analysis. Incorrect problem statement formation, flawed methodology, insufficient information on the applied method, ambiguity in models' coupling or cohesion, lack of rational explanation, and inappropriate interpretations of abnormal findings may even mislead many readers. This paper aims to point out some concerns related to the problems mentioned above in the published study, with suggestions to improve the current study and methodological notes for future research.

Microplastics and heavy metals in a tropical river: Understanding spatial and seasonal trends and developing response strategies using DPSIR framework

Microplastics (MPs) have become an increasingly popular topic in recent years due to the growing concern about their impact on human health and the environment. Rivers in Southeast Asia are the dominant source of plastics and MPs into the environment; however, research on MPs in rivers from the region is insufficient. This study aims to investigate the impacts of spatial and seasonal variations on the distribution of MPs with heavy metals in one of the top 15 rivers releasing plastics into oceans (Chao Phraya, Thailand). Findings from this study are analyzed using the Driver-Pressure-State-Impact-Response (DPSIR) framework for proposing strategies to minimize plastic and MPs in this tropical river. Spatially, most MPs were detected in the urban zone, while the lowest was in the agricultural zone. Also, MP levels in the dry season are higher than at the end but lower than at the beginning of the rainy season. MPs with fragment morphology were mainly found in the river (70-78 %). Polypropylene was found with the highest percentage (54-59 %). MPs in the river were mostly detected in the size range of 0.05-0.3 mm (36-60 %). Heavy metals were also found in all MPs collected from the river. Higher metal concentrations were detected in the agricultural and estuary zones in the rainy season. Potential responses, including regulatory and policy instruments, environmental education, and environmental cleanups, were drawn from the DPSIR framework.

Trace element contamination status of surface marine sediments of Greece: an assessment based on two decades (2001-2021) of data

This study is a first attempt to assess the trace element contamination status in the surface sediments of the Hellenic Seas since the first environmental studies in the country commenced in the mid-1970s. All available trace element data from the last 20 years have been collected and assessed using sediment quality guidelines and application of single- and multielement pollution indices. Although Hellenic marine sediments initially appear as anthropogenically enriched in Cr and As, this enrichment is attributed to the natural background. Central Greece appears more polluted, followed by Northern Greece and lastly Southern Greece. The element pollution indices featured the influence of industrial activities such as mining, steel industry and chemical factories, shipyards, and secondarily the influence of port activities.

A SEEC Model Based on the DPSIR Framework Approach for Watershed Ecological Security Risk Assessment: A Case Study in Northwest China

The DPSIR model is a conceptual model established by the European Environment Agency to solve environmental problems. It provides an overall framework for analysis of environmental problems from five aspects: driving force (D), pressure (P), state (S), impact (I), and response (R). Through use of the DPSIR model framework, this paper presents the SEEC model approach for evaluating watershed ecological security. The SEEC model considers four aspects: socioeconomic impact (S), ecological health (E), ecosystem services function (E), and control management (C). Through screening, 38 evaluation indicators of the SEEC model were determined. The evaluation results showed that the ecological security index of the study area was >80, indicating a generally safe level. The lowest score was mainly attributable to the low rate of treatment of rural domestic sewage. The water quality status was used to evaluate the applicability of the SEEC model, and the calculation results indicated that the higher the score of the ecological security evaluation results, the better the water quality status. The findings show that the SEEC model demonstrates satisfactory applicability to evaluation of watershed ecological security.

A holistic DPSIR-based approach to the remediation of heavily contaminated coastal areas

This paper proposes a holistic approach to connect anthropogenic impacts to environmental remediation solutions. The eDPSIR (engineered-Drivers-Pressures-States-Impacts-Responses) framework aims at supporting the decision-maker in designing technological solutions for a contaminated coastal area, where the natural matrices need to be cleaned up. The eDPSIR is characterized by cause-effect relationships that are operationally implemented through three multidisciplinary toolboxes: (i) Toolbox 1, to connect driving forces with pressures, classifying the state of the system and allowing the identification of target contaminants and the extent of contamination; (ii) Toolbox 2, to quantify bioaccumulation also by identifying corresponding areas; (iii) Toolbox 3, to identify the most suitable remediation solutions for previously identified contaminated areas, named contamination scenarios. The eDPSIR was calibrated on the case study of the Mar Piccolo in Taranto (Southern Italy), one of the most complex and polluted areas in Europe. While the consolidated DPSIR allows for a strategic response by limiting the use of contaminated areas or reducing upstream pressures, the eDPSIR made it possible to structure with a semi-quantitative logic the problem of assisting the decision-makers in choosing the optimal technological remediation responses for each sediment scenario of contamination (heavy metal; organic compounds; mixed). Assisted natural attenuation was identified as the best remediation technology in terms of treatment effectiveness and smallest amount of impacts involved in the project actions. However, considering the scenario of mixed contamination, in-situ reactive capping reached a good rank with a value of the composite indicator equal to 99.5%; thermal desorption and stabilization/solidification recorded a value of 94.1% and 84.6%, respectively. The application of these toolboxes provides alternative means to interpret, manage, and solve different cases of global marine contaminated sites.

The Drivers-Pressures-State-Impact-Response Model to Structure Cause−Effect Relationships between Agriculture and Aquatic Ecosystems

Different segments of society have shown interest in understanding the effects of human activities on ecosystems. To this end, the aim of this article is to analyze the scientific literature on the application of the Drivers-Pressures-State-Impact-Response (DPSIR) conceptual model to identify the parameters used to describe the causal interactions that occur between agriculture and aquatic ecosystems at the watershed scale. In this way, descriptive indicators were established for the data of 63 publications collected through Scopus, Web of Science, and Science Direct. The results confirm the great heterogeneity in the interpretation of the pressure, state, and impacts components. Part of this discrepancy can be attributed to the use of different indicators, as the model is flexible and generic. Overall, the DPSIR is a tool used not only in the scientific field, but also has demonstrated its potential to guide public policy formulation, planning, and decision-making in water resource management.

Small Patches of Riparian Woody Vegetation Enhance Biodiversity of Invertebrates

Patches of riparian woody vegetation potentially help mitigate environmental impacts of agriculture and safeguard biodiversity. We investigated the effects of riparian forest on invertebrate diversity in coupled stream-riparian networks using a case study in the Zwalm river basin (Flanders, Belgium). Agriculture is one of the main pressures in the basin and riparian forest is limited to a number of isolated patches. Our 32 study sites comprised nine unshaded “unbuffered” sites which were paired with nine shaded “buffered” sites on the same stream reach, along with five ‘least-disturbed’ sites and nine downstream sites. We sampled water chemistry, habitat characteristics and stream and riparian invertebrates (carabid beetles and spiders) at each site. Three methods were used to quantify riparian attributes at different spatial scales: a visually-assessed qualitative index, quantitative estimates of habitat categories in six rectangular plots (10 × 5 m) and geographic information system (GIS)-derived land cover data. We investigated relationships between invertebrates and riparian attributes at different scales with linear regression and redundancy analyses. Spiders and carabids were most associated with local riparian attributes. In contrast, aquatic macroinvertebrates were strongly influenced by the extent of riparian vegetation in a riparian band upstream (100–300 m). These findings demonstrate the value of quantifying GIS-based metrics of riparian cover over larger spatial scales into assessments of the efficacy of riparian management as a complement to more detailed local scale riparian assessments in situ. Our findings highlight the value of even small patches of riparian vegetation in an otherwise extensively disturbed landscape in supporting biodiversity of both terrestrial and freshwater invertebrates and emphasize the need to consider multiple spatial scales in riparian management strategies which aim to mitigate human impacts on biodiversity in stream-riparian networks.

Otolith fingerprints reveals potential pollution exposure of newly settled juvenile Sparus aurata

Coastal ecosystems are increasingly threatened by a wide range of human activities. Fish otolith chemistry, by creating a unique specific signature, can be used as a natural tag for determining life stage dispersal, spatial connectivity and population structure. In this study, we tested whether differences in otolith composition among juveniles of gilthead sea bream, Sparus aurata, could enable their proper allocation to polluted areas based on higher concentrations of elements related to contaminants. Otoliths were embedded, sectioned and analysed by LA-ICP-MS in line scan mode. Multivariate analysis confirmed clear separation between sites and elements. Samples from the site under the strongest anthropogenic impact from industrial and agricultural river input were characterized by higher values of Pb/Ca and Zn/Ca. However, these relatively low values likely do not have a negative effect on S. aurata recruitment, though they could serve for identifying the contribution of polluted nurseries to stock dynamics.

Conservation Requirements of European Eel (Anquilla anquilla) in a Balkan Catchment

The European eel (Anquilla anquilla) has been declining throughout its area of distribution, is addressed in several pieces of legislation, and is the target of extensive restoration efforts. Therefore, investigating and conserving natural eel habitats is urgently needed. Large, near-natural rivers have become rare in Europe but the Balkans host some of the extant examples. However, several Balkan rivers–among them the transboundary river Vjosa/Aoos of Albania and Greece–are under threat from planned hydropower constructions. This study synthesizes European eel catch data from four institutions and the results of a recent electrofishing survey. Population density and structure as well as habitat choice were studied at different spatial scales. We calculated densities for each meso-habitat (0–1303 ind./ha) and extrapolated these values across three different hydromorphological channel sections (meandering: 70 ind./ha, braided: 131 ind./ha, constrained: 334 ind./ha), resulting in an overall mean density of 168 ind./ha. Proposed hydropower plants would cut off about 80% of the catchment currently accessible and impact river sections downstream of the dams by disturbing hydrological dynamics. By linking study results to relevant legislation and literature we provide evidence-based data for water management decisions. We call for the Vjosa/Aoos to be protected in order to secure its outstanding conservation value.

Adapting the Index of Watershed Integrity for Watershed Managers in the Western Balkans Region

Sustainable development supports watershed processes and functions. To aid the sustainable development of the western Balkans' transboundary river and lake basins, the Regional Environmental Center for Central and Eastern Europe and the US Environmental Protection Agency (EPA) adapted the EPA's Index of Watershed Integrity (IWI) following the devasting 2014 floods in Albania, Bosnia and Herzegovina, Kosovo, North Macedonia, Montenegro, and Serbia. The IWI evaluates six watershed functions based on a suite of anthropogenic stressors (e.g., impervious surfaces, reservoirs). A key feature of the IWI is its ability to accumulate the impact of upstream activities of any specific location in a river network. A novel feature of the IWI, compared with other watershed assessment tools, is its capacity to provide actionable information at the local scale. IWI scores-ranging from 0 (low integrity) to 1 (high integrity)-calculated for the 1084 catchments of the study area indicated highest integrity in the Alpine geographic region (mean = 0.55, standard deviation (SD) = 0.11) and intermediate to lowest integrity within the Mediterranean (mean = 0.49, SD = 0.12) and Continental (mean = 0.40, SD = 0.10) geographic regions. The IWI results are presented hierarchically for data analysts (stressor, functional component, Index of Catchment Integrity and IWI), ecologists (stream/catchment, watershed, basin), and managers (local, national, international). We provide real-world examples for managers, and suggestions for improving the assessment.

Unraveling Aquatic Quality Controls of a Nearly Undisturbed Mediterranean Island (Samothraki, Greece)

Due to its rough, mountainous relief, Samothraki remains one of the last minimally disturbed islands in the Mediterranean. This paper examines the hydrogeochemical regime of the island’s surface waters as it results from geological, morphological, and hydro(geo)logical controls within a frame of minimally disturbed environmental conditions. Shallow, fractured groundwater aquifers, in combination with steep slopes and predominant weathering resistant rocks, bring about flashy stream regimes with remarkably low solute concentrations. Streams and springs revealed hydrochemical similarities. Contrary to streams chiefly draining sedimentary rocks, streams underlined by granite and ophiolite rocks do not respond hydrochemically to geochemical differences. Using ion proportions instead of concentrations, geochemical fingertips of magmatic stream basins were detected. Atmospheric inputs largely affect stream and spring composition, e.g., by 75% regarding sodium. Only 20% of dissolved oxygen and pH variance was assigned to biological activity, while nutrient levels were consistent with the undisturbed conditions of the island, except nitrate. Small mountainous springs and brooks fed by restricted, fractured groundwater aquifers with perennial flow, despite scarce summer rainfalls, may be fueled by cloud and fog condensation. High night-day stream flow differences, high atmospheric humidity predominately occurring during the night, and low stream water travel times point out toward this phenomenon.

Sediment Dynamics of the Neretva Channel (Croatia Coast) Inferred by Chemical and Physical Proxies

We examined the transport of sediments and their surficial pathways from the mouth of Neretva River, through the Neretva Channel, toward the Adriatic Sea. This research was based on twelve box-cores and five grab samples collected within the Neretva Channel. Sediment dynamics were evaluated using several proxies, such as organic matter, radiochemical isotopes and select metal concentrations and physical parameters. The data analysis showed that the influence of the river on particle distribution along the Neretva Channel decreases northward, with an estimated sediment accumulation rate ranging from 1.9 to 8.5 mm/yr. The lowest accumulation rate was found in the sector not influenced by river inflow, whereas the preferential sediment accumulation area is in the center of the basin. We speculate that dispersion and accumulation of sediments are both driven by an eddy in the waters of the Neretva Channel triggered/or intensified seasonally by the interaction of karstic springs, river input and Adriatic Sea waters. Our results indicate that the anthropogenic factor does not affect the concentration of metals within the channel and that the river particles dynamics determine the Pb areal distribution, while Cr and Ni have a possible source located to the northwest of the river-mouth.

Modeling the Effects of Anthropogenic Land Cover Changes to the Main Hydrometeorological Factors in a Regional Watershed, Central Greece

In this study, the physically-based hydrological model MIKE SHE was employed to investigate the effects of anthropogenic land cover changes to the hydrological cycle components of a regional watershed in Central Greece. Three case studies based on the land cover of the years 1960, 1990, and 2018 were examined. Copernicus Climate Change Service E-OBS gridded meteorological data for 45 hydrological years were used as forcing for the model. Evaluation against observational data yielded sufficient quality for daily air temperature and precipitation. Simulation results demonstrated that the climatic variabilities primarily in precipitation and secondarily in air temperature affected basin-averaged annual actual evapotranspiration and average annual river discharge. Nevertheless, land cover effects can locally outflank the impact of climatic variability as indicated by the low interannual variabilities of differences in annual actual evapotranspiration among case studies. The transition from forest to pastures or agricultural land reduced annual actual evapotranspiration and increased average annual river discharge while intensifying the vulnerability to hydrometeorological-related hazards such as droughts or floods. Hence, the quantitative assessment of land cover effects presented in this study can contribute to the design and implementation of successful land cover and climate change mitigation and adaptation policies.

Water Quality and Hydromorphological Variability in Greek Rivers: A Nationwide Assessment with Implications for Management

European rivers are under ecological threat by a variety of stressors. Nutrient pollution, soil erosion, and alteration in hydrology are considered the most common problems that riverine ecosystems are facing today. Not surprisingly, river monitoring activities in Europe have been intensified during the last few years to fulfil the Water Framework Directive (WFD) requirements. With this article, we present a nationwide assessment of the water quality and hydromorphological variability in Greek Rivers based on the results of the national monitoring program under the WFD. Water quality and hydromorphological data from 352 sites belonging to 221 rivers were explored with principal component analysis (PCA) to identify main environmental gradients and the variables that contribute the most to the total variance. Nitrate, phosphate, ammonium and electrical conductivity were identified as the most important water chemistry parameters, and typical vector-based spatial data analysis was applied to map their spatial distribution at sub-basin scale. In addition, we conducted simple linear models between the aforementioned parameters and the share of land uses within the basin of each sampling site in order to identify significant relationships. Agriculture was the most important land use affecting the nitrate and electrical conductivity, while artificial surfaces were the best predictor for phosphate and ammonium. Concerning the hydromorphological variability, fine types of substrate and discharge were the variables with the highest contribution to the total variance. Overall, the results of this article can be used for the preliminary assessment of susceptible areas/rivers to high levels of nutrient pollution that can aid water managers to formulate recommendations for improvement of further monitoring activities. Furthermore, our findings implicate the need for enhancement of agri-environmental measures and reduction of point-source pollution in disturbed areas to avert the risk of further environmental degradation under the anticipated global change.

Designing the National Network for Automatic Monitoring of Water Quality Parameters in Greece

Water quality indices that describe the status of water are commonly used in freshwater vulnerability assessment. The design of river water quality monitoring programs has always been a complex process and despite the numerous methodologies employed by experts, there is still no generally accepted, holistic and practical approach to support all the phases and elements related. Here, a Geographical Information System (GIS)-based multicriteria decision analysis approach was adopted so as to contribute to the design of the national network for monitoring of water quality parameters in Greece that will additionally fulfill the urgent needs for an operational, real-time monitoring of the water resources. During this cost-effective and easily applied procedure the high priority areas were defined by taking into consideration the most important conditioning factors that impose pressures on rivers and the special conditions that increase the need for monitoring locally. The areas of increased need for automatic monitoring of water quality parameters are highlighted and the output map is validated. The sites in high priority areas are proposed for the installation of automatic monitoring stations and the installation and maintenance budget is presented. Finally, the proposed network is contrasted with the current automatic monitoring network in Greece.

River Basin Management Plans as a tool for sustainable transboundary river basins' management

Data availability and the existence of exchange mechanisms are considered crucial issues for the management of water bodies shared among riparian countries. Moreover, common legislative and technical frameworks are assets that foster the management of transboundary waters in an integrated and sustainable manner. The River Basin Management Plans of the European Union's Water Framework Directive implementation process not only incorporate a cooperative framework, but also include open access internet-based databases that can enhance cooperation and shed light on water-related conflicts among countries that share transboundary waters. The proposed methodological approach in this research is applied in four transboundary river basins, where Greece is the downstream country, and the upstream countries are not all member states of the European Union. The areas of dispute were found in the 2nd Water Convention Report. For each particular case study, data and information from the respective River Basin Management Plans were used to investigate the actual situation. The results demonstrated that significant conflict situations in the past, which involved both water quality and water quantity issues, could be resolved using continuous and reliable datasets included in the management plans. The use of freely available data sources renders the findings of this work useful for the sustainable management of shared waters.

Socio-economic factors influencing farmers' willingness to undertake environmental responsibility

Acknowledging the importance of water resources protection and sustainable management, the European Parliament enacted directives based on the "polluter-pays" principle aiming for "environmental damage" protection and restoration of water resources. The main aim of this paper is to examine, for the first time in Greece, the possibility of achieving environmental goals, such as reduction of agrochemical pollution and irrigation water use, alongside with the farmers' willingness to undertake the environmental costs arising from their activity. In a questionnaire survey, conducted using a "state preference" method, participants were asked to respond on whether they are willing to absorb an "environmental charge" for the protection and restoration of surface and ground water. It is an essential precondition to understand the factors that affect taxpayers' willingness to participate in the Water Framework Directive, as they are expected to cover the cost of its implementation. The identification of the driving forces that affect stakeholders' environmental decisions can emerge as an important and useful tool in extending public participation in the Water Framework Directive.

An Integrated Analysis of the Eutrophication Process in the Enxoé Reservoir within the DPSIR Framework

The Enxoé reservoir in southern Portugal has been exhibiting the highest trophic state in the country since its early years of operation. The problem has attracted water managers’ and researchers’ attention as the reservoir is the water supply for two municipalities. Extensive research was thus conducted over the last few years, including field monitoring and modelling at the plot, catchment, and reservoir scales. This study now frames all partial findings within the Driver-Pressure-State-Impact-Response (DPSIR) framework to better understand the eutrophication process in the Enxoé reservoir. Agriculture and grazing were found to have a reduced role in the eutrophication of the reservoir, with annual sediment and nutrient loads being comparably smaller or similar to those reported for other Mediterranean catchments. Flash floods were the main mechanism for transporting particle elements to the reservoir, being in some cases able to carry up three times the average annual load. However, the main eutrophication mechanisms in the reservoir were P release from deposited sediment under anoxic conditions and the process of internal recycling of organic matter and nutrients. Reducing the P load from the catchment and deposited sediment could lead to a mesotrophic state level in the reservoir. However, this level would only be sustainable by limiting the P internal load ability to reach the photic zone.

The organic pollutant status of rivers in Bosnia and Herzegovina as determined by a combination of active and passive sampling methods

There is an overall lack of data concerning the pollution status of Bosnia Herzegovina, which is confounded by fragmented national environmental management. The present study aimed to provide some initial data for concentrations of priority substances in two major Bosnian Rivers, using two types of passive sampler (PS) as well as by using high volume water sampling (HVWS). Overall, concentrations of most persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs) and legacy pesticides, were shown to be low. However, around the town of Doboj on the Bosna River, concentrations of polycyclic aromatic hydrocarbons (PAH) breached European standards for several compounds and reached 67 ng L^-1 for freely dissolved concentrations and 250 ng L^-1 for total concentrations. In general, contamination was lower in the Neretva River compared to the Bosna, although for brominated diphenyl ethers (PBDEs), results suggested an active source of PBDEs at one location based on the ratio of congeners 47 and 99. Direct comparisons between the different sampling techniques used are not straightforward, but similar patterns of PAH contamination were shown by HVWS and PS in the Bosna River. There are both scientific and practical considerations when choosing which type of sampling technique to apply, and this should be decided based on the goals of each individual study.

Microevolution of the noble crayfish (Astacus astacus) in the Southern Balkan Peninsula

Background

The noble crayfish (Astacus astacus) displays a complex historical and contemporary genetic status in Europe. The species divergence has been shaped by geological events (i.e. Pleistocene glaciations) and humanly induced impacts (i.e. translocations, pollution, etc.) on its populations due to species commercial value and its niche degradation. Until now, limited genetic information has been procured for the Balkan area and especially for the southernmost distribution of this species (i.e. Greece). It is well known that the rich habitat diversity of the Balkan Peninsula offers suitable conditions for genetically diversified populations. Thus, the present manuscript revisits the phylogenetic relationships of the noble crayfish in Europe and identifies the genetic make-up and the biogeographical patterns of the species in its southern range limit.

Results

Mitochondrial markers (i.e. COI and 16S) were used in order to elucidate the genetic structure and diversity of the noble crayfish in Europe. Two of the six European haplotypic lineages, were found exclusively in Greece. These two lineages exhibited greater haplotypic richness when compared with the rest four (of “Central European” origin) while they showed high genetic diversity. Divergence time analysis identified that the majority of this divergence was captured through Pleistocene, suggesting a southern glacial refugium (Greece, southern Balkans). Furthermore, six microsatellite markers were used in order to define the factors affecting the genetic structure and demographic history of the species in Greece. The population structure analysis revealed six to nine genetic clusters and eight putative genetic barriers. Evidence of bottleneck effects in the last ~5000 years (due to climatic and geological events and human activities) is also afforded. Findings from several other research fields (e.g. life sciences, geology or even archaeology) have been utilized to perceive the genetic make-up of the noble crayfish.

Conclusions

The southernmost part of Balkans has played a major role as a glacial refugium for A. astacus. Such refugia have served as centres of expansion to northern regions. Recent history of the noble crayfish in southern Balkans reveals the influence of environmental (climate, geology and/or topology) and anthropogenic factors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-017-0971-6) contains supplementary material, which is available to authorized users.

Building multi-country collaboration on watershed management: lessons on linking environment and public health from the Western Balkans

Community-based watershed resilience programs that bridge public health and environmental outcomes often require cross-boundary, multi-country collaboration. The CRESSIDA project, led by the Regional Environmental Center for Central and Eastern Europe (REC) and supported by the US Environmental Protection Agency (EPA), forwards a resilience-focused approach for Western Balkan communities in the Drini and Drina river watersheds with the goal of safeguarding public health and the environment. The initial phases of this project give a contextualized example of how to advance resilience-driven environmental health goals in Western Balkan communities, and experience within the region has garnered several theme areas that require focus in order to promote a holistic watershed management program. In this paper, using CRESSIDA as a case study, we show (1) how watershed projects designed with resilience-driven environmental health goals can work in context, (2) provide data surrounding contextualized problems with resilience and suggest tools and strategies for the implementation of projects to address these problems, and (3) explore how cross-boundary foci are central to the success of these approaches in watersheds that comprise several countries.

Non-perennial Mediterranean rivers in Europe: Status, pressures, and challenges for research and management

Non-perennial rivers and streams (NPRS) cover >50% of the global river network. They are particularly predominant in Mediterranean Europe as a result of dry climate conditions, climate change and land use development. Historically, both scientists and policy makers underestimated the importance of NRPS for nature and humans alike, mainly because they have been considered as systems of low ecological and economic value. During the past decades, diminishing water resources have increased the spatial and temporal extent of artificial NPRS as well as their exposure to multiple stressors, which threatening their ecological integrity, biodiversity and ecosystem services. In this paper, we provide a comprehensive overview of the structural and functional characteristics of NPRS in the European Mediterranean, and discuss gaps and problems in their management, concerning their typology, ecological assessment, legislative and policy protection, and incorporation in River Basin Management Plans. Because NPRS comprise highly unstable ecosystems, with strong and often unpredictable temporal and spatial variability - at least as far as it is possible to assess - we outline the future research needs required to better understand, manage and conserve them as highly valuable and sensitive ecosystems. Efficient collaborative activities among multidisciplinary research groups aiming to create innovative knowledge, water managers and policy makers are urgently needed in order to establish an appropriate methodological and legislative background. The incorporation of NPRS in EU-Med River Basin Management Plans in combination with the application of ecological flows is a first step towards enhancing NPRS management and conservation in order to effectively safeguard these highly valuable albeit threatened ecosystems.

Biogeochemical processes controlling aquatic quality during drying and rewetting events in a Mediterranean non-perennial river reach

Desiccation and re-flooding processes play a key role on hydrological features of non-perennial rivers. This study addresses the effects of these processes on the aquatic quality and unravels underlying biogeochemical processes of an intermittent river reach in southern Greece containing a spring-fed pool. Combined spatio-temporal sampling for physicochemical parameters, major ions and nutrients and high frequency automatic monitoring during a hydrological year (2010-2011) indicate that during the dry period, solute variation was controlled by "concentration" processes (i.e. evaporative concentration and high dissolved ion input from base flow sources). Metabolic and "concentration" processes appear intensified during desiccation and water temperature rise. Photosynthesis induced carbonate precipitation, while respiration increased with gradual desiccation, but did not cause carbonate dissolution. In certain cases, photosynthesis and respiration may have occurred simultaneously as a result of differing microhabitat metabolism within the same water body. However, during the entire desiccation cycle, autotrophic production exceeded respiration resulting in relatively high oxygen concentrations, even during the night. With increasing desiccation, a rise in nutrient assimilation occurred as well as ammonification and/or desorption of ammonium from sediments, with simultaneous loss of nitrate. During initial floods, flushing of carbonate phases was not significant. In contrast, initial flood events were characterized by the dissolution of very soluble salts, i.e. epsomite-type (MgSO₄∗7H₂O) and gypsum (CaSO₄∗2H₂O). Regarding sediment transport and nutrients, a 1000-times increase of suspended sediments was observed during re-flooding, while the nutrient quality degraded, particularly for N-species. Results of the current research may serve to better understand the links of hydrological and biogeochemical processes in non-perennial rivers and streams towards their efficient management and conservation.

Which lesson can be learnt from a historical contamination analysis of the most polluted river in Europe?

The Sarno River trend analysis during the last 60 years was traced focusing on the socio-economic and environmental issues. The river, originally worshiped as a god by Romans, is affected by an extreme level of environmental degradation, being sadly reputed as the most polluted river in Europe. This is the "not to be followed" example of the worst way a European river can be managed. Data about water, sediment, soil, biota and air contamination were collected from scientific papers, monitoring surveys, and technical reports depicting a sick river. Originally, the river was reputed as a source of livelihood, now it is considered a direct threat for human health. Wastewater can still flow through the river partially or completely untreated, waste production associated with the manufacture of metal products and leather tanning continues to suffer from the historical inadequacy of regional wastewater treatment plants (WWTPs), associated with the partial or no reuse of effluents. All efforts should be devoted to solving the lack of wastewater and waste management, the gap in land planning, improving the capacity of existing WWTPs also via the construction of new sewer sections, restoring Sarno River minimum vital-flow, keeping to a minimum uncontrolled discharges as well as supporting river contracts. The 2015 goal stated by the Water Framework Directive (2000/60/EC) is still far to be reached. The lesson has not been learnt yet.

Colored dissolved organic matter dynamics and anthropogenic influences in a major transboundary river and its coastal wetland

Most transboundary rivers and their wetlands are subject to considerable anthropogenic pressures associated with multiple and often conflicting uses. In the Eastern Mediterranean such systems are also particularly vulnerable to climate change, posing additional challenges for integrated water resources management. Comprehensive measurements of the optical signature of colored dissolved organic matter (CDOM) were combined with measurements of river discharges and water physicochemical and biogeochemical properties, to assess carbon dynamics, water quality, and anthropogenic influences in a major transboundary system of the Eastern Mediterranean, the Evros (or, Марица or, Meriç) river and its Ramsar protected coastal wetland. Measurements were performed over three years, in seasons characterized by different hydrologic conditions and along transects extending more than 70 km from the freshwater end-member to two kilometers offshore in the Aegean Sea. Changes in precipitation, anthropogenic dissolved organic matter (DOM) inputs from the polluted Ergene tributary, and the irregular operation of a dam were key factors driving water quality, salinity regimes, and biogeochemical properties in the Evros delta and coastal waters. Marsh outwelling affected coastal carbon quality, but the influence of wetlands was often masked by anthropogenic DOM contributions. A distinctive five-peak CDOM fluorescence signature was characteristic of upstream anthropogenic inputs and clearly tracked the influence of freshwater discharges on water quality. Monitoring of this CDOM fluorescence footprint could have direct applications to programs focusing on water quality and environmental assessment in this and other transboundary rivers where management of water resources remains largely ineffective.

Effects of olive oil wastes on river basins and an oligotrophic coastal marine ecosystem: a case study in Greece

This work aims to contribute to the knowledge of the impacts of olive oil waste discharge to freshwater and oligotrophic marine environments, since the ecological impact of olive oil wastes in riverine and coastal marine ecosystems, which are the final repositories of the pollutants, is a great environmental problem on a global scale, mostly concerning all the Mediterranean countries with olive oil production. Messinia, in southwestern Greece, is one of the greatest olive oil production areas in Europe. During the last decade around 1.4×10(6)tons of olive oil mill wastewater has been disposed in the rivers of Messinia and finally entered the marine ecosystem of Messiniakos gulf. The pollution from olive oil mill wastewater in the main rivers of Messinia and the oligotrophic coastal zone of Messiniakos gulf and its effects on marine organisms were evaluated, before, during and after the olive oil production period. Elevated amounts of phenols (36.2-178 mg L(-1)) and high concentrations of ammonium (7.29-18.9 mmol L(-1)) and inorganic phosphorus (0.5-7.48 mmol L(-1)) were measured in small streams where the liquid disposals from several olive oil industries were gathered before their discharge in the major rivers of Messinia. The large number of olive oil units has downgraded the riverine and marine ecosystems during the productive period and a period more than five months is needed for the recovery of the ecosystem. Statistical analysis showed that the enrichment of freshwater and the coastal zone of Messiniakos gulf in ammonia, nitrite, phenols, total organic carbon, copper, manganese and nickel was directly correlated with the wastes from olive oil. Toxicity tests using 24h LC50 Palaemonidae shrimp confirm that olive mill wastewater possesses very high toxicity in the aquatic environment.

Decision support methods for the environmental assessment of contamination at mining sites

Polluting mine accidents and widespread environmental contamination associated with historic mining in Europe and elsewhere has triggered the improvement of related environmental legislation and of the environmental assessment and management methods for the mining industry. Mining has some unique features such as natural background pollution associated with natural mineral deposits, industrial activities and contamination located in the three-dimensional sub-surface space, the problem of long-term remediation after mine closure, problem of secondary contaminated areas around mine sites and abandoned mines in historic regions like Europe. These mining-specific problems require special tools to address the complexity of the environmental problems of mining-related contamination. The objective of this paper is to review and evaluate some of the decision support methods that have been developed and applied to mining contamination. In this paper, only those methods that are both efficient decision support tools and provide a 'holistic' approach to the complex problem as well are considered. These tools are (1) landscape ecology, (2) industrial ecology, (3) landscape geochemistry, (4) geo-environmental models, (5) environmental impact assessment, (6) environmental risk assessment, (7) material flow analysis and (8) life cycle assessment. This unique inter-disciplinary study should enable both the researcher and the practitioner to obtain broad view on the state-of-the-art of decision support methods for the environmental assessment of contamination at mine sites. Documented examples and abundant references are also provided.

Management of groundwater resources in relation to oasis sustainability: the case of the Nefzawa region in Tunisia

In Southern Tunisia Nefzawa region, the deep fossil aquifers have been used intensively to support agricultural activities and economic development. This resulted in the degradation of groundwater resources as well as in their conflicting uses. Efficient management strategies that allow for compromises between economic development and water resource preservation are needed. Such strategies require initial understanding of the interactions between stakeholders and water related processes. This paper aims to conceptualize the causalities between the management of deep fossil aquifers and the functioning of oasian agrosystems. By merging biophysical and socioeconomic issues, we propose an integrated assessment of public policies devoted to the management of groundwater resources. The failure of public policies emphasizes both the lack of consideration for individual initiatives and the long-term uncertainties on such policies, where farmer practices have been driven by economic and cultural factors. A set of indicators is next proposed for assessing the preservation of deep fossil aquifers that support agricultural and economic development. Further methodological improvements are needed to evaluate the long-term effects of constraints and incentives on the management of deep fossil aquifers.

Screening for Stockholm Convention persistent organic pollutants in the Bosna River (Bosnia and Herzogovina)

The Stockholm Convention, which aspires to manage persistent organic pollutants (POPs) at the international level, was recently ratified in Bosnia and Herzegovina (BiH). Despite this fact, there is in general a paucity of data regarding the levels of POPs in the environment in BiH. In the present study, screening for POPs was conducted in one of the country's major rivers, the Bosna. A two-pronged approach was applied using passive samplers to detect the freely dissolved and bioavailable concentrations in the water phase and sediment analysis to provide an integrated measure of historical contamination. At several places along the river, the concentrations of polycyclic aromatic hydrocarbons (PAH) were high and exhibited potential for both chronic and acute effects to biota. River water also showed elevated concentrations of PAH, up to 480 ng L(-1) near the city of Doboj, and diagnostic ratios suggested combustion sources for the contamination present in both types of sample. The levels of the other contaminants measured-polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers--were generally low in the water phase. However, PCBs and some OCPs were present in river sediments at levels which breach the international criteria and thus suggest potential for ecological damage. Additionally, the levels of heptachlor breached these criteria in many of the sites investigated. This study presents the first screening data for some of these Stockholm Convention relevant compounds in BiH and reveals both low concentrations of some chemical groups, but significant point sources and historic contamination for others.

A risk-based approach to prioritise catchments for diffuse metal pollution management

Catchment management integrates a wide range of water management aspects taking into account the interaction between land-use and water quality. While most sources of pollution can be identified, monitoring and tackling diffuse pollution are difficult due to the abundance of its sources and pathways. As a result, the application of risk assessment of diffuse pollution at the catchment level has been limited. This study aimed to develop a risk-based approach to rank and prioritise catchments based on the need for managing diffuse metal pollution, using a multi-criteria evaluation framework. Source-pathway-receptor linkages were the basis for the selection of criteria and associated indicators. The methodology was applied to eight catchments located in the Humber River Basin District (RBD) that were comparatively evaluated, and difficulties in selecting weightings for the criteria used were discussed. Results showed that Don and Rother, Aire and Calder and Trent were the three catchments with the highest risk of diffuse metal pollution in this RBD. The findings demonstrate the potential of the proposed risk-based approach to inform more detailed investigations to follow and prioritise the need for investments on relevant programmes to prevent diffuse metal pollution in catchments where these are needed most.

Phylogeography of isolated freshwater three-spined stickleback Gasterosteus aculeatus populations in the Adriatic Sea basin

Analyses of mitochondrial (mt) DNA and microsatellite variation were carried out to examine the relationships between 10 freshwater populations of three-spined sticklebacks Gasterosteus aculeatus along the eastern coast of the Adriatic Sea. Partial sequences of the mtDNA control region and cytochrome b gene, in addition to 15 microsatellite loci, were used to analyse populations from four isolated river catchments. Results uncovered an Adriatic lineage that was clearly divergent from the European lineage, and confirmed that the most divergent and ancient populations are located within the Adriatic lineage as compared with other European populations. Two northern Adriatic populations formed independent clades within the European mitochondrial lineage, suggesting different colonization histories of the different Adriatic populations. Nuclear marker analyses also indicated deep divergence between Adriatic and European populations, albeit with some discordance between the mtDNA phylogeny of the northern Adriatic populations, further highlighting the strong differentiation among the Adriatic populations. The southern populations within the Adriatic lineage were further organized into distinct clades corresponding to respective river catchments and sub-clades corresponding to river tributaries, reflecting a high degree of population structuring within a small geographic region, concurrent with suggestions of existence of several microrefugia within the Balkan Peninsula. The highly divergent clades and haplotypes unique to the southern Adriatic populations further suggest, in accordance with an earlier, more limited survey, that southern Adriatic populations represent an important reservoir for ancient genetic diversity of G. aculeatus.

Development of spatial water resources vulnerability index considering climate change impacts

This study developed a new framework to quantify spatial vulnerability for sustainable water resources management. Four hydrologic vulnerability indices--potential flood damage (PFDC), potential drought damage (PDDC), potential water quality deterioration (PWQDC), and watershed evaluation index (WEIC)--were modified to quantify flood damage, drought damage, water quality deterioration, and overall watershed risk considering the impact of climate change, respectively. The concept of sustainability in the Driver-Pressure-State-Impact-Response (DPSIR) framework was applied in selecting all appropriate indicators (criteria) of climate change impacts. In the examination of climate change, future meteorological data was obtained using CGCM3 (Canadian Global Coupled Model) and SDSM (Statistical Downscaling Model), and future stream run-off and water quality were simulated using HSPF (Hydrological Simulation Program - Fortran). The four modified indices were then calculated using TOPSIS, a multi-attribute method of decision analysis. As a result, the ranking obtained can be changed in consideration of climate change impacts. This study represents a new attempt to quantify hydrologic vulnerability in a manner that takes into account both climate change impacts and the concept of sustainability.

Mercury in white stork (Ciconia ciconia) chick feathers from northeastern Mediterranean areas in relation to age, brood size, and hatching order

Mercury (Hg) levels in white stork (Ciconia ciconia) feathers collected in the mid-1990s from five northeastern Mediterranean (Greece) areas varied, with mean ranges between 301 ng g(-1) dry weight (dw) (Pinios River) and 1911 ng g(-1) dw (Sperchios Delta). A significant increase of Hg levels in chick feathers with age (surrogated by bill size) was found in the Evros and Pinios River areas, a nonsignificant increase in the Amvrakikos Gulf and the Epirus Region, and a marginally significant decrease in the Sperchios Delta area. For combined data of 1993 and 1995, Hg concentrations did not differ significantly in relation to hatching order among broods but differed significantly in relation to brood size being higher in 4-chick broods than those in 3-chick broods. All 10 areas formed 4 groups with levels mutually significantly different. Highest levels were detected in the Evros, Axios, and Sperchios riverine areas, whereas the lowest levels occurred at Drama plain, which lacks large water bodies in its vicinity. Levels were lower than those associated with intoxication to other ciconiiform species.

Stability of the total and functional microbial communities in river sediment mesocosms exposed to anthropogenic disturbances

River systems are exposed to anthropogenic disturbances, including chemical pollution and eutrophication. This may affect the phylogenetic diversity as well as the abundance of various functional groups within sediment-associated microbial communities. To address such potential effects, mesocosms filled with Ebro delta sediment covered with river water were exposed to chlorinated organic compounds or to a high nutrient concentration as used for fertilization. Changes in the abundance of selected functional microbial groups, i.e. total aerobes, nitrate, sulfate and iron reducers, organohalide-respiring microorganisms as well as methanogens, were examined using culture-dependent most probable number and culture-independent PCR methods targeting phylogenetic as well as functional gene markers. It was concluded that the abundance of functional groups was neither affected by pollution with 1,2-dichloroethane and tetrachloroethene nor by elevated nutrient loads, although changes in the bacterial community composition were observed using 16S rRNA gene-targeted fingerprint techniques. This study reinforced the notion that complementary culture-dependent and molecular methods, focusing on different fractions of the microbial community (cultivable, active or total), should be used in combination for a comprehensive description of phylogenetic diversity and functional potential.