Acute and sub-chronic toxicity bioassays of Olive Mill Wastewater on the Eastern mosquitofish Gambusia holbrooki.

Olive oil production generates large volumes of wastewaters mostly in peri-Mediterranean countries with adverse impacts on the biota of the receiving aquatic systems. Few studies have however documented its toxicity on aquatic species, with an almost total lack of relative studies on fish. We assessed the acute and sub-chronic OMW toxicity, as well as the acute and sub-chronic behavioural, morphological and biochemical effects of OMW exposure on the mosquitofish Gambusia holbrooki. LC50 values of the acute bioassays ranged from 7.31% (24 h) to 6.38% (96 h). Behavioural symptoms of toxicity included hypoactivity and a shift away from the water surface, coupled with a range of morphological alterations, such as skin damage, excessive mucus secretion, hemorrhages, fin rot and exophhalmia, with indications also of gill swelling and anemia. Biochemical assays showed that OMW toxicity resulted in induction of catalase (CAT) and inhibition of acetylcholinesterase (AChE) activities. The implications of our results at the level of environmental policy for the sustainable management of the olive mill industry, i.e. the effective restriction of untreated OMW disposal of in adjacent waterways, as well as the implementation of new technologies that reduce their impact (detoxification and/or revalorization of its residues) are discussed.

Water quality and benthic fauna biodiversity in a unique small wetland at Messinia, Greece.

The wetland of Aghios Floros is located in the Prefecture of Messinia (S. W. Peloponnese, Greece) and occupies a small area, covered permanentlywith water. Flooding of the surrounding area is defended by an artificial channel that discharge large quantity of water into Pamisos River in whose river basin the Aghios Floros station belongs. At the sampling site various physico-chemical and conventional pollution parameters as well as hydrochemical variables were measured during the wet and the dry period of 2011. The hydromorphological and multihabitat approach of RIVPACS method was applied in situ, which gives an overall image of the landscape. The site was classified as 'Good' according to the Greek River Nutrient Classification System (GR.NCS) and the benthic macroinvertebrate fauna assemblages that dominated the area pointed out a 'Good' biological status as well. The biotic and abiotic sample processing, carried out in compliance with the demands of the Water Framework Directive, in general revealed high ecological status of the station. Specifically, a rich diversity and abundance of some macroinvertebrate families was recorded and regarding the aquatic flora the area is dominated by the water lilies species of Nymphaea alba which are unique in the area of Peloponnese.

Geology Can Drive the Diversity-Ecosystem Functioning Relationship in River Benthic Diatoms by Selecting for Species Functional Traits.

The biodiversity-ecosystem functioning (BEF) relationship has been studied extensively for the past 30 years, mainly in terrestrial plant ecosystems using experimental approaches. Field studies in aquatic systems are scarce, and considering primary producers, they mainly focus on phytoplankton assemblages, whereas benthic diatoms in rivers are considerably understudied in this regard. We performed a field study across nine rivers in Greece, and we coupled the observed field results with model simulations. We tested the hypothesis that the diversity-biomass (as a surrogate of ecosystem functioning) relationship in benthic diatoms would be affected by abiotic factors and would be time-dependent due to the highly dynamic nature of rivers. Indeed, geology played an important role in the form of the BEF relationship that was positive in siliceous and absent in calcareous substrates. Geology was responsible for nutrient concentrations, which, in turn, were responsible for the dominance of specific functional traits. Furthermore, model simulations showed the time dependence of the BEF form, as less mature assemblages tend to present a positive BEF. This was the first large-scale field study on the BEF relationship of benthic diatom assemblages, offering useful insights into the function and diversity of these overlooked ecosystems and assemblages.

Stable isotopes reveal organic nitrogen pollution and cycling from point and non-point sources in a heavily cultivated (agricultural) Mediterranean river basin.

The Pinios River Basin (PRB) is the most intensively cultivated area in Greece, which hosts numerous industries and other anthropogenic activities. The analysis of water samples collected monthly for ∼1 ½ years in eight monitoring sites in the PRB revealed nitrate pollution of organic origin extending from upstream to downstream and occurring throughout the year, masking the signal from the application of synthetic fertilizers. Nitrate concentrations reached up to 3.6 mg/l as NO3--N, without exceeding the drinking water threshold of ∼11.0 mg/l (as NO3--N). However, the water quality status was "poor" or "bad" in ∼50 % of the samples based on a local index, which considers the potential impact of nitrate on aquatic biological communities. The δ15Ν-ΝΟ3- and δ18O-NO3- values ranged from +4.4 ‰ to +20.3 ‰ and from -0.5 ‰ to +14.4 ‰, respectively. The application of a Bayesian model showed that the proportional contribution of organic pollution from industries, animal breeding facilities and manure fertilizers exceeded 70 % in most river sites with an overall uncertainty of ∼0.3 (UI90 index). The δ18O-NO3- and its relationship with δ18O-H2O revealed N-cycling and mixing processes, which were difficult to identify apart from the uptake of nutrients by phytoplankton during the growing season and metabolic activities. The strong correlation of δ15Ν-ΝΟ3- values with a Land Use Index (LUI) and a Point Source Index (PSI) highlighted not only the role of non-point nitrate sources but also of point sources of nitrate pollution on water quality degradation, which are usually overlooked. The nitrification of organic wastes is the dominant nitrate source in most rivers in Europe. The systematic monitoring of rivers for nitrate isotopes will help improve the understanding of N-cycling and the impact of these pollutants on ecosystems and better inform policies for protection measures so to achieve good ecological status.

Sources of major elements and nutrients in the water cycle of an undisturbed river basin - Samothraki Island, Greece.

We studied the origin of elements of an undisturbed stream basin during the dry season as derived by atmospheric inputs and lithological processes. Α mass balance model was applied taking into account atmospheric (rain and vapor) inputs and their origin from marine aerosol and dust, as well as the contribution of rock mineral weathering and dissolution of soluble salts. The model results were enhanced using element enrichment factors, element ratios and water stable isotopes. Weathering and dissolution of bedrock and soil minerals contributed the main element portions, besides sodium and sulfate that chiefly derived from wet deposition. Vapor was shown to contribute water to inland waters of the basin. However, rain was the main source of elements compared to vapor, with marine aerosol being the only atmospheric chloride source, contributing also over 60 % of atmospheric sodium and magnesium. Silicate derived from mineral weathering (mainly plagioclase and amorphous silica), while soluble salt dissolution contributed the main portions of the rest of major elements. In headwater springs and streams, element concentrations were more affected by atmospheric inputs and silicate mineral weathering was more intense, contrary to lowland waters that were more affected by soluble salt dissolution. Effective self-purification processes were mirrored in low nutrient levels, despite the significant inputs from wet deposition, with rain being more important contributor than vapor for the majority of nutrient species. Relatively high nitrate concentrations in headwaters were attributed to increased mineralization and nitrification, while the downstream nitrate diminishing was due to prevailing denitrification processes. The ultimate goal of this study is to contribute in establishing stream elements' reference conditions using mass balance modeling approaches.

Bioassays and biochemical biomarkers for assessing olive mill and citrus processing wastewater toxicity.

The toxicity and the biochemical effects of olive mill wastewater and citrus processing wastewater were evaluated using acute toxicity bioassays (Gammarus pulex and Hydropsyche peristerica) and biochemical biomarkers (acetylcholinesterase [AChE] and glutathione S-transferase [GST]). The bioassays indicated toxic properties of olive mill and citrus processing wastewaters. The 24 h LC(50) values of olive mill wastewater ranged from 2.64% to 3.36% for G. pulex and 3.62% to 3.88% for H. peristerica, while the LC(50) of citrus processing wastewater was 25.26% for G. pulex and 17.16% for H. peristerica. Based on a five-class hazard classification system applied for wastewaters discharged into the aquatic environment, olive mill wastewater and citrus processing wastewater were classified as highly toxic and toxic, respectively. Results of the biochemical biomarkers showed that both agroindustrial effluents at increasing sublethal wastewater concentrations could cause inhibition of the AChE and induction of the GST activities. These first results showed that both species as well as their AChE and GST activities have the potential to be used as indicators and biomarkers for assessing olive mill and citrus processing wastewaters quality.

Levels, sources and spatiotemporal variation of nutrients and micropollutants in small streams of a Mediterranean River basin.

In this study, nutrients, trace metals and priority pesticide compounds were investigated for the first time in water and sediment samples in streams of the Evrotas River basin (S.E. Greece) from 2006 to 2008. The most important sources of contamination were from the entry of pesticides and nutrients into surface waters and sediments as a result of the intensive agricultural activity as well as from the uncontrolled disposal of olive mill and citrus processing wastewaters. Aquatic risk assessment revealed that all insecticides detected showed high risk, suggesting adverse effects on the stream biota. Among the metals analyzed, Cr, Ni and Ba presented the highest concentrations in sediments, however, due to natural geological processes. Multivariate statistical techniques applied for data compression, exploration and interpretation proved to be useful tools for identifying the most critical pollutants affecting the surface water quality. The findings of this study suggest that the inclusion of streams with small catchment areas into WFD monitoring and assessment programs is essential, especially those of the Mediterranean region.

Heavy metal contamination status in Greek surface waters: A review with application and evaluation of pollution indices.

Heavy metal contamination of the aquatic environment is of worldwide concern, due to the toxicity of metals and their lethal effects on aquatic organisms. The investigation of heavy metal concentrations in freshwater bodies has increased over the last decades in Greece; however, most studies have been sporadic and spatially limited. An overall assessment of the heavy metal contamination status in Greek surface water bodies is lacking. In this review, all available published data from 1999 to 2019 were collected and analysed to assess the heavy metal contamination status of the surface water bodies of Greece. Data were available for 68 water bodies and several pollution indices (e.g. Heavy Metal Pollution index, Geoaccumulation index, Moderated Pollution Index) were calculated to evaluate their surface water quality. Overall, heavy metal concentrations in water samples were below the Environmental Quality Standards (EQS) and the vast majority of water bodies were classified as good quality based on surface water pollution indices. Sediment heavy metal concentrations exceeding the Sediment Quality Guidelines (SQGs) were detected in most water bodies. Rivers Axios, Evros, Louros, Gallikos, Greveniotikos, Palea Kavala, Kompsatos, Alfeios and Evrotas, and lakes Pamvotis, Doirani and Koumoundourou were either moderately or highly contaminated. Up to date, heavy metal pollution indices used worldwide for surface waters refer to potable water. Thus, pollution indices must be developed for assessing primarily the ecological consequences of heavy metal pollution and surface water pollution status. Finally, sediment pollution guidelines must be suggested at a European or regional level.

Priority and emerging organic microcontaminants in three Mediterranean river basins: Occurrence, spatial distribution, and identification of river basin specific pollutants.

There is a worldwide growing use of chemicals by our developed, industrialized, and technological society. More than 100,000 chemical substances are thus commonly used both by industry and households. Depending on the amount produced, physical-chemical properties, and mode of use, many of them may reach the environment and, notably, the aquatic receiving systems. This may result in undesirable and harmful side-effects on both the human and the ecosystem's health. Mediterranean rivers are largely different from Northern and Central European rivers in terms of hydrological regime, climate conditions (e.g. air temperature, solar irradiation, precipitation), and socio-economics (e.g. land use, tourism, crop types, etc.), with all these factors leading to differences in the relative importance of the environmental stressors, in the classes and levels of the pollutants found and their environmental fate. Furthermore, water scarcity might be critical in affecting water pollution because of the lowered dilution capacity of chemicals. This work provides raw chemical data from different families of microcontaminants identified in three selected Mediterranean rivers (the Sava, Evrotas, and Adige) collected during two sampling campaigns conducted in 2014 and 2015 in three different matrices, namely, water, sediments, and biota (fish). More than 200 organic micropollutants were analyzed, including relevant groups like pharmaceuticals, personal care products, perfluorinated compounds, pesticides, pyrethroid insecticides, flame retardants, and persistent organic pollutants. Data obtained were summarized with some basic statistics for all compound families and matrices analyzed. Observed occurrence and spatial patterns were interpreted both in terms of compound physical-chemical properties and local environmental pressures. Finally, their spatial distribution was examined and their ecotoxicological risk in the water phase was assessed. This allowed locating, at each basin, the most polluted sites ("hot spots") and identifying the respective river basin specific pollutants (RBSPs), prioritizing them in terms of the potential ecotoxicological risk posed to the aquatic ecosystems.

River restoration is prone to failure unless pre-optimized within a mechanistic ecological framework | Insights from a model-based case study.

River restoration with the use of in-stream structures has been widely implemented to maintain/improve physical habitats. However, the response of aquatic biota has often been too weak to justify the high costs of restoration projects. The ecological effectiveness of river restoration has thus been much debated over claims that large-scale environmental drivers often overshadow the potential positive ecological effects of locally placed in-stream structures. In this study, we used a two-dimensional hydrodynamic-habitat model to evaluate the ecological effectiveness of habitat restoration with the use of in-stream structures in various water discharges, ranging from near-dry to environmental flows. The habitat suitability of benthic macroinvertebrates and of three cyprinid fish species was simulated for six restoration schemes and at four discharge scenarios, and was compared with a reference model, without in-stream structures. We found that the ecological response to habitat restoration varied by species and life stages, it strongly depended on the reach-scale flow conditions, it was often negative at near-environmental flows, and when positive, mostly at near-dry flows, it was too low to justify the high costs of river restoration. Flow variation was the major environmental driver that our local habitat restoration schemes attempted -but mostly failed-to fine-tune. We conclude that traditional river restoration, based on trial and error, will likely fail and should be ecologically pre-optimized before field implementation. Widespread use of in-stream structures for ecological restoration is not recommended. However, at near-dry flows, the response of all biotic elements except for macroinvertebrates, was positive. In combination with the small habitat-suitability differences observed among structure types and densities, we suggest that sparse/moderate in-stream structure placement can be used for cost-effective river restoration, but it will only be ecologically effective -thus justifying the high implementation costs-when linked to very specific purposes: (i) to conserve endangered species and (ii) to increase/improve habitat availability/suitability during dry periods, thus proactively preventing/reducing the current and future ecological impacts of climate change.

Minimizing human error in macroinvertebrate samples analyses for ensuring quality precision in freshwater monitoring programs.

Benthic macroinvertebrates are often used in ecological quality monitoring. However, due to the large number of samples and specimens, sample processing (sorting/identification) is a labor-intensive task that is susceptible to errors. These errors can consequently lead to biased assessment results. We conducted the first audit of the Greek National Water Monitoring program. Totally, 444 samples were sorted at the laboratory by primary sorters and macroinvertebrate identification was conducted mainly at family level by primary taxonomists, having different taxonomic expertise. The Percentage Sorting Efficiency (PSE), Percentage of Taxonomic Disagreement (PTD), and the Relative Percentage Difference (RPD) were calculated to determine differences between auditing stages. Control charts were used to determine the process changes of the personnel (sorting: PSE index and identification: PTD index) as a calibration check. Additionally, national ecological indices/metrics were calculated to identify how they are affected by errors. All samples except from one had PSE values higher than 90%. The most common overlooked families were Chironomidae, followed by Baetidae and Gammaridae due to their high abundances. Average values of the PTD index for the total number of samples was 5.75% and 1.86% in each phase, respectively. The PTD values decreased between the two phases due to the gained experience of primary taxonomists during the 1st phase. The average action control limit was 95% for the PSE values and 14% for the PTD values. Overall, our ecological quality results indicated that the sorting error was less important than the identification one as the latter may lead to different ecological quality classifications. Our results show that our auditing procedure is effective and increases the quality and accuracy of the sample analysis procedure. It also highlights that human error should not be neglected since it may affect the ecological quality results and especially the good/moderate boundary which leads to rehabilitation measures.

Unravelling the effects of multiple stressors on diatom and macroinvertebrate communities in European river basins using structural and functional approaches.

Rivers suffer from more severe decreases in species diversity compared to other aquatic and terrestrial ecosystems due to a variety of pressures related to human activities. Species provide different roles in the functioning of the ecosystem, and their loss may reduce the capacity of the ecosystems to respond to multiple stressors. The effects on diversity will differ based on the type, combination and severity of stressors, as well as on the characteristics of the community composition and tolerance. Multiple trait-based approaches (MTBAs) can help to unravel the effects of multiple stressors on communities, providing a mechanistic interpretation, and, thus, complementing traditional biodiversity assessments using community structure. We studied the relationships between diversity indexes and trait composition of macroinvertebrate and diatom communities, as well as environmental variables that described the hydrological and geomorphological alterations and toxic pollution (pesticides and pharmaceuticals) of three different European river basins: the Adige, the Sava, and the Evrotas. These river basins can be considered representative cases of different situations in European freshwater systems. Hydrological variables were the main drivers determining the community structure and function in the rivers, for both diatoms and macroinvertebrates. For diatom communities, pharmaceutical active compound (PhAC) toxic units were also identified as a very important driver of diversity changes, explaining up to 57% of the variance in taxonomic richness. For macroinvertebrates, river geomorphology was an important driver of structural changes, particularly affecting Plecoptera richness. In addition, PhAC and pesticide toxic units were also identified as stressors for macroinvertebrate communities. MTBA provided a detailed picture of the effects of the stressors on the communities and confirmed the importance of hydrological variables in shaping the functional attributes of the communities.

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

Fifteen major Balkan rivers with over 80% of the inflows in Eastern Mediterranean were examined for their environmental state within the DPSIR framework. Physicogeographic and hydrochemical conditions differ substantially among river basins, which may be roughly classified into three main zones. Despite strong fragmentation, most of the rivers are liable to flash floods and have low summer flow. Decreasing precipitation and (mis)management caused a dramatic discharge reduction over the last decades. Wars, political instability, economical crises over the past decades, combined with administrative and structural constraints, poor environmental planning and inspection and, frequently, a lack of environmental awareness imposed significant pressures on rivers. Large wetland areas were drained in favour of widespread intensive agriculture. The treatment of municipal wastewaters is barely adequate in Greece and insufficient elsewhere, while management and treatment of mining and industrial wastewaters is overall poor. In general, lowland river sections are hydro-morphologically modified and are at the greatest pollution risk, while upstream areas mostly retain their natural conditions. Nutrient concentrations in a number of central and eastern Balkan rivers often exceed quality standards, whereas pesticides and heavy metals, partly of geochemical origin, occasionally exceed quality standards. Reservoirs retain vast masses of sediments, thus adversely affecting delta evolution, while dam operation disturbs the seasonal hydrological and hydrochemical regimes. Almost all Balkan countries face daunting water resource challenges because of urgently needed investments in water supply, sanitation, irrigation, and hydroelectricity. International treaties and designations and European Union Directives have mobilized pollution mitigation and conservation efforts. However, the application of environmental legislation has proved in a number of cases inadequate. Constraints arise from long-standing top-down planning traditions, inadequate planning of national environmental policies, poor administrative capacities, and heavy investment requirements, often combined with a lack of environmental awareness.

Contamination patterns and attenuation of pharmaceuticals in a temporary Mediterranean river.

The contamination patterns and fate of pharmaceutically active compounds (PhACs) were investigated in the Evrotas River (Southern Greece). This is a temporary river with differing levels of water stress and water quality impairment in a number of its reaches. Three sampling campaigns were conducted in order to capture different levels of water stress and water quality. Four sampling sites located on the main channel of the Evrotas River were sampled in July 2015 (moderate stream flow), and June and September 2016 (low stream flow). Discharge of urban wastewater has been determined as the main source of pollution, with PhACs, nutrients and other physicochemical parameters considerably increasing downstream the wastewater treatment plant (WWTP) of Sparta city. Due to the pronounced hydrological variation of the Evrotas River, generally, the highest concentrations of PhACs have been detected during low flow conditions. Simultaneously, low flow resulted in an increased water travel time and consequently longer residence time that accounted for the higher attenuation of most PhACs. The average decrease in total concentration of PhACs within the studied waterbody segment (downstream of Sparta city) increased from 22% in July 2015 to 25% in June 2016 and 77% in September 2016. The PhACs with the highest average concentration decrease throughout the sampling campaigns were hydrochlorothiazide, followed by sotalol, carbamazepine, valsartan, and naproxen.

Stream invertebrate communities are primarily shaped by hydrological factors and ultimately fine-tuned by local habitat conditions.

The environmental factors that determine species richness and community structure in running waters have long been studied, but how these factors hierarchically and/or interactively influence benthic communities remains unclear. To address this research gap, we identified the principal abiotic factors that determine the taxonomic composition and functionality of stream macroinvertebrate communities and explored possible hierarchical and/or interactive patterns. We analyzed a large dataset from Greek rivers, and compared multiple macroinvertebrate metrics and traits between perennial and intermittent watercourses during wet and dry periods. We found that macroinvertebrates were primarily influenced by two ecological gradients: (i) aquatic vegetation-conductivity; and (ii) water temperature-canopy cover. Macroinvertebrates in perennial rivers were mainly influenced by the first gradient, whereas in intermittent rivers both gradients were important. Taxonomic richness and diversity were higher and temporally stable within years in perennial rivers, whereas in intermittent rivers, these metrics peaked during early summer, before the onset of streambed desiccation. The two environmental gradients determined the taxonomic richness and diversity in both spring and summer; however, a clear influence of hydrological factors (wetted width, water depth, flow velocity and discharge) was observed only in the intermittent samples. We conclude that the benthic invertebrate taxonomic richness and diversity in highly variable environments is primarily determined by hydrological variation and ultimately fine-tuned by local habitat factors. As climate change scenarios predict severe modification of hydrological and local habitat factors, this study concludes that in river management, hydrological restoration should be prioritized over other local habitat factors by maintaining natural hydrological variability, to ensure aquatic community richness and diversity.

Potentially toxic elements in water, sediments and fish of the Evrotas River under variable water discharges.

Among different stressors like drought, hydro-morphological alterations, and pollution from agricultural activities, nutrients, organic compounds and discharges from wastewater treatment plants (WWTPs), potentially toxic elements (PTE) may also contribute to the overall pollution of the Evrotas River, Greece. Nevertheless, information on pollution of elements in water and sediments in this river is scarcely documented. There is also no information available on the impact of elemental pollution from the aquatic environmental compartments on biota. To fill these gaps, in this study, water, sediment and fish samples were collected from four sampling sites along the Evrotas River under variable flow regimes (July 2015, higher discharge; June 2016, low discharge and September 2016, minimum discharge). Total and dissolved element concentrations in water samples, total and acetic acid extractable contents in sediments, and element concentrations in fish samples were determined by inductively coupled plasma mass spectrometry and significant relationships between samples were established using correlation analysis. The concentrations of PTE (Ni, Cr, Cd, As, Pb, Zn and Cu) in water were generally low, while elevated Ni and Cr contents were found in sediments (up to 150 and 300 mg/kg, respectively), with total Cr concentration in water and sediment being positively correlated. The ecological risk posed by the simultaneous presence of PTE in sediments evaluated by calculating the Probable Effect Concentration Coefficient (PEC-Q), demonstrated that PEC-Qs, which were above the critical value of 0.34, derived mostly from Cr and Ni inputs. Since their mobile sediment fraction was extremely low, Cr and Ni origin is most probably geogenic. The analysis of elements in the target fish species, the Evrotas chub, showed low to moderate PTE concentrations, with Pb being positively correlated with total Pb concentration in water. Moderate Zn concentrations found in fish samples from the Evrotas are possibly derived from pesticides and fertilizers.

Personal care products reconnaissance in EVROTAS river (Greece): Water-sediment partition and bioaccumulation in fish.

Twenty-six common ingredients of personal care products (PCPs) in water, sediment and fish from the Evrotas River (Greece) were investigated. Water sample analysis revealed the occurrence of twenty PCPs at concentrations ranging from 2.8 to 2031.0 ng l-1, the maximum corresponding to the endocrine disrupting UV filter benzophenone 3 (BP3). In sediment samples, six compounds were found to be adsorbed, the highest concentration being that of 4-methylbenzylidene camphor (4MBC, 1400.4 ng g-1 dw). Evrotas cyprinid fish (Squalius keadicus) showed a high accumulation potential for these chemicals, 100% detection frequency with maximum concentration that of benzophenone 2 (BP2, 41.9 ng g-1 dw). These data allowed estimating the distribution coefficients sediment-water (DCs-w) and the bioaccumulation factors (BAFs) of the pollutants investigated. Calculated rates revealed that benzophenone 1 (BP1), 4-hydroxybenzophenone (4HB) and ethyl-4-(dimethyl-amino)benzoate (EtPABA) have a strong tendency to adsorb onto the sediments, showing high DCs-w, i.e. 8.2E + 4 l g-1, 6.7E + 4 l g-1 and 5.7E + 3 l g-1, respectively. BFAs were only estimated for 5-methyl benzotriazole (MeBT), the compound having paired data from fish and water. The obtained values (range 2.0E + 2 l g-1-3.8E + 3 l g-1), indicated MeBT's strong bioaccumulation. Risk assessment of the investigated compounds for several aquatic organisms indicated a high ecological risk (HQ > 1) for BP3 and medium ecological risk (HQ ~ 0.5) for ODPABA.

Effects of olive mill wastewater discharge on benthic biota in Mediterranean streams.

Olive mill wastewaters (OMW) discharging in river ecosystems cause significant adverse effects on their water chemistry and biological communities. We here examined the effects of OMW loads in four streams of a Mediterranean basin characterized by changing flow. The diatom and macroinvertebrate community structures were compared between upstream (control) and downstream (impacted) sites receiving OMW discharge. We also tested if effects occurred at the organism level, i.e. the occurrence of deformities in diatom valves, and the sediment toxicity on the midge Chironomus riparius. We evaluated these effects through a two-year analysis, at various levels of chemical pollution and dilution capacity. The impacted sites had high phenol concentrations and organic carbon loads during and after olive mill (OM) operation, and were characterized by higher abundances of pollution-tolerant diatom and macroinvertebrate taxa. Diatom valve deformities occurred more frequently at the impacted sites. The development of C. riparius was affected by phenolic compounds and organic carbon concentrations in the sediments. The similarity in the diatom and macroinvertebrate assemblages between control and impacted sites decreased at lower flows. Diatoms were more sensitive in detecting deterioration in the biological status of OMW receiving waterways than macroinvertebrates. Our results indicate that the negative effects of OMW extended to the whole benthic community, at both assemblage and organism level.

Down scaling of climate change scenarii to river basin level: A transdisciplinary methodology applied to Evrotas river basin, Greece.

The Mediterranean region is anticipated to be (or, already is) one of the hot spots for climate change, where freshwater ecosystems are under threat from the effects of multiple stressors. Climate change is impacting natural resources and on the functioning of Ecosystem Services. The challenges about modelling climate change impact on water cycle in general and specifically on socio-economic dynamics of the society leads to an exponential amount of results that restrain interpretation and added value of forecasting at local level. One of the main challenges when dealing with climate change projections is the quantification of uncertainties. Modellers might have limited information or understanding from local river catchment management practices and from other disciplines with relevant insights on socio-economic and environmental complex relationship between biosphere and human based activities. Current General Circulation Models cannot fulfil the requirements of high spatial detail required for water management policy. This article reports an innovative transdisciplinary methodology to down scale Climate Change scenarii to river basin level with a special focus on the development of climate change narrative under SSP5-RCP8.5 combination called Myopic scenario and SSP1-RCP4.5 combination called Sustainable scenario. Local Stakeholder participative workshop in the Evrotas river basin provide perception of expected changes on water demand under to two developed scenario narratives.

Multiple stressor effects on biodiversity and ecosystem functioning in a Mediterranean temporary river.

The hydrological and biological complexity of temporary rivers as well as their importance in providing goods and services is increasingly recognized, as much as it is the vulnerability of the biotic communities in view of climate change and increased anthropogenic pressures. However, the effects of flow intermittency (resulting from both seasonal variations and rising hydrological pressure) and pollution on biodiversity and ecosystem functioning have been overlooked in these ecosystems. We explore the way multiple stressors affect biodiversity and ecosystem functioning, as well as the biodiversity-ecosystem functioning (B-EF) relationship in a Mediterranean temporary river. We measured diversity of benthic communities (i.e. diatoms and macroinvertebrates) and related ecosystem processes (i.e. resource use efficiency-RUE and organic matter breakdown-OMB) across a pollution and flow intermittency gradient. Our results showed decreases in macroinvertebrate diversity and the opposite trend in diatom assemblages, whereas ecosystem functioning was negatively affected by both pollution and flow intermittency. The explored B-EF relationships showed contrasting results: RUE decreased with higher diatom diversity, whereas OMB increased with increased macroinvertebrate diversity. The different responses suggest contrasting operating mechanisms, selection effects possibly driving the B-EF relationship in diatoms and complementarity effects driving the B-EF relationship in macroinvertebrates. The understanding of multiple stressor effects on diversity and ecosystem functioning, as well as the B-EF relationship in temporary rivers could provide insights on the risks affecting ecosystem functioning under global change.