Bioconcentration and bioaccumulation of C60 fullerene and C60 epoxide in biofilms and freshwater snails (Radix sp.)

Fullerenes are carbon nanomaterials that have awaken a strong interest due to their adsorption properties and potential applications in many fields. However, there are some gaps of information about their effects and bioconcentration potential in the aquatic biota. In the present work, freshwater biofilms and snails (Radix sp.) were exposed to fullerene C₆₀ aggregates, at concentrations in the low μg/L order, in mesocosms specifically designed to mimic the conditions of a natural stream. The bioconcentration factors of C₆₀ fullerene and its main transformation product, [6,6]C₆₀O epoxide, were studied to the mentioned organisms employing analyses by liquid chromatography coupled to high-resolution mass spectrometry. Our results show that C₆₀ fullerene and its [6,6]C₆₀O present a low bioconcentration factor (BCF) to biofilms: BCF_C60 = 1.34 ± 0.95 L/kg_dw and BCF_C60O = 1.43 ± 0.72 L/kg_dw. This suggests that the sorption of these aggregates to biota may be less favoured than it would be suggested by its hydrophobic character. According to our model, the surface of fullerene aggregates is saturated with [6,6]C₆₀O molecules, which exposes the polar epoxide moieties in the surface of the aggregates and decreases their affinity to biofilms. In contrast, freshwater snails showed a moderate capacity to actively retain C₆₀ fullerenes in their organism (BAF_C60 = 2670 ± 3070 L/kg_dw; BAF_C60O = 1330 ± 1680 L/kg_dw), probably through ingestion. Our results indicate that the bioaccumulation of these carbon nanomaterials can be hardly estimated using their respective octanol-water partition coefficients, and that their colloidal properties, as well as the feeding strategies of the tested organism, play fundamental roles.

Is one brachytherapy fraction of 7 Gy similar to more fractions after external beam irradiation in postoperative endometrial carcinoma?

PURPOSE

To determine whether brachytherapy with a single hypofractionated dose of 7 Gy provides the similar vaginal-cuff relapses and safety profile in terms of complications compared to schedules of 2 or 3 fractions of lower doses in patients treated previously with external beam irradiation in postoperative endometrial carcinoma.

METHODS/MATERIAL

From June 2003 to December 2016, 325 patients were treated with 3 different schedules of high-dose-rate brachytherapy after external beam irradiation for postoperative endometrial carcinoma. The patients were divided into 3 groups: Group-1: 125 patients were treated with 3 fractions of 4-6 Gy per fraction (3 fractions/week) between 2003 and 2008; Group-2: 93 patients were treated with 2 consecutive daily fractions of 5-6 Gy between 2008 and 2011; Group-3: 107 patients received a single fraction of 7 Gy between 2011 and 2016. Bladder and rectum complications were assessed using RTOG scores and with the objective scores of LENT-SOMA for the vagina.

STATISTICS

the chi-square test.

RESULTS

The mean follow-up of Groups 1, 2 and 3 was 95, 67 and 51 months, respectively. Three patients in Group-1, 2 in Group-2, 1 in Group-3 developed vaginal-cuff relapse (p = 0.68). No differences were found in late toxicity among the three groups.

CONCLUSIONS

One single dose of 7 Gy is safe and effective and may be the best treatment schedule with a similar incidence of vaginal-cuff relapses, complications and patient comfort with less hospital attendance.

Effects of radiotherapy on plasma energy metabolites in patients with breast cancer who received neoadjuvant chemotherapy

PURPOSE

Neoadjuvant chemotherapy (NACT) is employed in patients with breast cancer (BC) with the aim of reducing tumor burden and improving surgical outcomes. We evaluated the levels of energy metabolites pre- and post-radiotherapy (RT) in breast cancer (BC) patients who previously received NACT and investigated the alterations of these metabolites in relation to the patient achieving a pathologic complete response to NACT.

MATERIALS AND METHODS

We included 37 BC patients who were treated with NACT following surgery and analyzed the concentrations of energy balance-related metabolites using targeted metabolomics before and one month after the end of RT. The control group was composed of 44 healthy women.

RESULTS

Pre-radiotherapy, patients had significant decreases in the plasma levels of 12 metabolites. RT corrected these alterations and the improvement was superior in patients with a pathologic complete response.

CONCLUSION

Our results highlight the importance of metabolism in the outcomes of patients with BC.

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.

Exposure to single and binary mixtures of fullerenes and triclosan: Reproductive and behavioral effects in the freshwater snail Radix balthica

Emerging pollutants occur in complex mixtures in rivers and have the potential to interact with freshwater organisms. The chronic effects of nominal exposure to 3 μg/L of fullerenes (C₆₀) and 1 μg/L of triclosan (TCS) alone and in a binary mixture, were evaluated using the freshwater snail Radix balthica. Pollutants accumulation, reproductive output and feeding behavior were selected as sublethal endpoints. After 21 days of exposure, we did not observe interactive effects between TCS and C₆₀ on the studied endpoints, except for the accumulation of C₆₀ in R. balthica in TCS + C₆₀ treatment, which was lower than when the fullerenes were alone. Neither TCS nor C₆₀ caused significant effects on reproduction, expressed as number of eggs per individual, but an increase in the clutch size was observed in treatments with TCS at the third week of exposure, independently of the presence of C₆₀ (16.15 ± 1.67 and 18.9 ± 4.01 eggs/egg mass in TCS and TCS + C₆₀ treatments, respectively, vs. 13.17 ± 4.01 in control). The presence of C₆₀ significantly enhanced the grazing activity of R. balthica during the first seven days (4.95 ± 1.35 and 3.91 ± 0.59% of the area grazed per individual in C₆₀ and TCS + C₆₀ treatments, respectively, vs 2.6 ± 0.39% in control). The accumulation of TCS was quite similar in treatments where this pollutant was present (BAF ≈ 1007 L/kg d.w.); however, the accumulation of C₆₀ was higher when the nanoparticles were alone (BAF = 254.88 L/kg d.w.) than when it was in the binary mixture (BAF = 7.79 L/kg d.w). Overall, although TCS has been listed as an endocrine disrupter compound, no significant effects on reproduction were observed in the assayed conditions. Regarding C₆₀, the limited effects on feeding activity and the low BAF obtained in this experiment indicate that fullerenes do not have ecological consequences of relevance at the studied environmental concentrations in freshwater snails.

Nutrient attenuation dynamics in effluent dominated watercourses

In-stream attenuation of dissolved and particulate forms of carbon, nitrogen and phosphorus are a crucial ecosystem service, especially in watercourses downstream of chemical pollution point-sources (i.e. wastewater treatment plants). Most chemical-fate models assume that attenuation is directly proportional to the concentration of available dissolved organic carbon, and inorganic nitrogen and phosphorus compounds in watercourses, but there are multiple evidences of saturation and even inhibition of attenuation at higher concentrations. Our current comprehension of nutrient attenuation kinetics in streams remains a limiting factor for the development and calibration of predictive models of the chemical fate of these compounds in rivers, thus hindering the development and implementation of more effective regulatory strategies. Here, we assessed the in-stream attenuation of dissolved organic carbon, inorganic nitrogen (NH₄⁺, NO₂^-, NO₃^-) and phosphorus (PO₄^3-) compounds at increasing concentrations of these compounds, and analyzed the interaction between attenuation kinetics and biofilm structure and function. Specifically, the net balances of these compounds were assessed in artificial streams exposed to eight treatments following the gradient of WWTP contribution to the river flow (0, 14, 29, 43, 58, 72, 86, and 100% of WWTP effluent water). Results indicate that biological in-stream attenuation by a given biofilm of an effluent dominated watercourse might be saturated if exposed for short periods to high nutrient concentrations such as during combined sewer overflow events, but that communities can adapt if exposed long enough to high concentrations, therefore avoiding or at least minimizing saturation. More attention should be therefore given to the management of effluent-dominated watercourses, as reductions in the temporal variability of the discharged wastewater by WWTP might enhance attenuation and thus reduce water quality issues downstream.

Invertebrate community responses to urban wastewater effluent pollution under different hydro-morphological conditions

Urban wastewater effluents bring large amounts of nutrients, organic matter and organic microcontaminants into freshwater ecosystems. The effects of this complex mixture of pollutants on freshwater invertebrates have been studied mainly in temperate rivers and streams with high dilution capacities. In contrast, Mediterranean streams and rivers have lower dilution capacities especially during the seasonal drought, and are therefore exposed to high concentrations of pollutants. Here, we assess the effects of urban wastewater pollution on invertebrate communities from Mediterranean streams under different hydrological conditions. Specifically, we assessed the invertebrates taxonomic composition and functional biological traits in 12 streams, differing in stream and substrate size (sand or cobbles), under low (2 surveys) and baseflow (1 survey) conditions. In each stream, we selected reaches both upstream and downstream of the wastewater discharge point. Our results indicate that urban wastewater pollution favours the most tolerant invertebrate taxa and homogenises functional trait composition over time. Changes in functional traits were more evident during the seasonal drought, when the low flow conditions at the upstream and downstream sites were more severe and, pollutant concentrations downstream were at their highest. However, the effects of urban wastewater pollution were not uniform in the downstream sites; as local invertebrate communities differed in according to the river substrate and stream size (i.e., width and discharge). Overall, urban pollution caused by wastewater enhanced both, taxonomic and functional differences between the invertebrate communities. Such an absence of homogenisation among wastewater pollution impacted sites was probably related to the relevant role of stream substrate-size as well flow conditions in the rivers receiving the impact. These are attributes that need to be considered when setting the pollutant discharge limits in rivers and streams receiving effluents.

Protecting and restoring Europe's waters: An analysis of the future development needs of the Water Framework Directive

The Water Framework Directive (WFD) is a pioneering piece of legislation that aims to protect and enhance aquatic ecosystems and promote sustainable water use across Europe. There is growing concern that the objective of good status, or higher, in all EU waters by 2027 is a long way from being achieved in many countries. Through questionnaire analysis of almost 100 experts, we provide recommendations to enhance WFD monitoring and assessment systems, improve programmes of measures and further integrate with other sectoral policies. Our analysis highlights that there is great potential to enhance assessment schemes through strategic design of monitoring networks and innovation, such as earth observation. New diagnostic tools that use existing WFD monitoring data, but incorporate novel statistical and trait-based approaches could be used more widely to diagnose the cause of deterioration under conditions of multiple pressures and deliver a hierarchy of solutions for more evidence-driven decisions in river basin management. There is also a growing recognition that measures undertaken in river basin management should deliver multiple benefits across sectors, such as reduced flood risk, and there needs to be robust demonstration studies that evaluate these. Continued efforts in 'mainstreaming' water policy into other policy sectors is clearly needed to deliver wider success with WFD goals, particularly with agricultural policy. Other key policy areas where a need for stronger integration with water policy was recognised included urban planning (waste water treatment), flooding, climate and energy (hydropower). Having a deadline for attaining the policy objective of good status is important, but even more essential is to have a permanent framework for river basin management that addresses the delays in implementation of measures. This requires a long-term perspective, far beyond the current deadline of 2027.

Desiccation events change the microbial response to gradients of wastewater effluent pollution

While wastewater treatment plant (WWTP) effluents have become increasingly recognized as a stressor for receiving rivers, their effects on river microbial communities remain elusive. Moreover, global change is increasing the frequency and duration of desiccation events in river networks, and we ignore how desiccation might influence the response of microbial communities to WWTP effluents. In this study, we evaluated the interaction between desiccation events and WWTP effluents under different dilution capacities. Specifically, we used artificial streams in a replicated regressional design, exposing first a section of the streams to a 7-day desiccation period and then the full stream to different levels of a realistic WWTP effluent dilution, from 0% to 100% of WWTP effluent proportion of the total stream flow. The microbial community response was assessed by means of high-throughput sequencing of 16S rRNA gene amplicons and quantitative PCR targeting ecologically-relevant microbial groups. Threshold Indicator Taxa Analysis (TITAN) was used, together with model fitting, to determine community thresholds and potential indicator taxa. Results show significant interactions between WWTP effluents and desiccation, particularly when sediment type is considered. Indicator taxa included members of Proteobacteria, Actinobacteria and Cyanobacteria, with abrupt changes in community structure at WWTP effluent proportion of the total flow above 50%, which is related to nutrient levels ranging 4.6-5.2 mg N-NO₃^-L^-1, 0.21-0.32 mg P-PO₄^3-L^-1 and 7.09-9.00 mg DOC L^-1. Our work indicates that situations where WWTP effluents account for >50% of the total river flow might risk of dramatic microbial community structure changes and should be avoided.

Immediate and legacy effects of urban pollution on river ecosystem functioning: A mesocosm experiment

Effluents from urban wastewater treatment plants (WWTP) consist of complex mixtures of substances that can affect processes in the receiving ecosystems. Some of these substances (toxic contaminants) stress biological activity at all concentrations, while others (e.g., nutrients) subsidize it at low concentrations and stress it above a threshold, causing subsidy-stress responses. Thus, the overall effects of WWTP effluents depend mostly on their composition and the dilution capacity of the receiving water bodies. We assessed the immediate and legacy effects of WWTP effluents in artificial streams, where we measured the uptake of soluble reactive phosphorus (SRP) by the biofilm, biomass accrual, benthic metabolism and organic matter decomposition (OMD). In a first phase (32 d), the channels were subjected to a gradient of effluent contribution, from pure stream water to pure effluent. WWTP effluent affected the ecosystem processes we measured, although we found no clear subsidy-stress patterns except for biofilm biomass accrual. Instead, most of the processes were subsidized, although they showed complex and process-specific patterns. Benthic metabolism and OMD were subsidized without saturation, as they peaked at medium and high levels of pollution, respectively, but they never fell below control levels. SRP uptake was the only process that decreased with increasing effluent concentration. In a second phase of the experiment (23 d), all channels were kept on pure stream water to analyse the legacy effects of the effluent. For most of the processes, there were clear legacy effects, which followed either subsidy, stress, or subsidy-stress patterns. SRP uptake capacity was stressed with increasing pollution legacy, whereas algal accrual and benthic metabolism continued being subsidized. Conversely, biofilm biomass accrual and OMD showed no legacy effects. Overall, the WWTP effluent caused complex and process-specific responses in our experiment, mainly driven by the mixed contribution of subsidizers and stressors. These results help improving our understanding of the effects of urban pollution on stream ecosystem functioning.

Impact and mitigation of global change on freshwater-related ecosystem services in Southern Europe

Global change is severely impacting the biosphere that, through ecosystem services, sustains human well-being. Such impacts are expected to increase unless mitigation management actions are implemented. Despite the call from the scientific and political arenas for their implementation, few studies assess the effectiveness of actions on freshwater-related services. Here, by modeling water provisioning, water purification and erosion control under current and future conditions, we assess future trends of service provision with and without mitigation policies. In particular, two different storylines combine multiple climate, land use/land cover and agricultural management scenarios, and represent a pro-efficiency business as usual (myopic storyline) and a future that considers social and environmental sustainability (sustainable storyline). The mentioned services are modeled for the horizon 2050 and in three South European river basins: Ebro, Adige and Sava, which encompass the wide socio-environmental diversity of the region. Our results indicate that Mediterranean basins (Ebro) are extremely vulnerable to global change respect Alpine (Adige) or Continental (Sava) basins, as the Ebro might experience a decrease in water availability up to 40%, whereas the decrease is of only 2-4% in the Adige or negligible in the Sava. However, Mediterranean basins are also more sensitive to the implementation of mitigation actions, which would compensate the drop in water provisioning. Results also indicate that the regulating services of water purification and erosion control will gain more relevance in the future, as both services increased between 4 and 20% in both global change scenarios as a result of the expansion of agricultural and urban areas. Overall, the impact of global change is diverse among services and across river basins in Southern Europe, with the Mediterranean basins as the most vulnerable and the Continental as the least. The implementation of mitigation actions can compensate the impact and therefore deserves full political attention.

Impact of fullerenes in the bioaccumulation and biotransformation of venlafaxine, diuron and triclosan in river biofilms

A huge variety of organic microcontaminants are presently detected in freshwater ecosystems, but there is still a lack of knowledge about their interactions, either with living organisms or with other contaminants. Actually, carbon nanomaterials like fullerenes (C₆₀) can act as carriers of organic microcontaminants, but their relevance in processes like bioaccumulation and biotransformation of organic microcontaminants by organisms is unknown. In this study, mesocosm experiments were used to assess the bioaccumulation and biotransformation of three organic microcontaminants (venlafaxine, diuron and triclosan) in river biofilms, and to understand how much the concomitant presence of C₆₀ at environmental relevant concentrations could impact these processes. Results indicated that venlafaxine exhibited the highest bioaccumulation (13% of the initial concentration of venlafaxine in water), while biotransformation was more evident for triclosan (5% of the initial concentration of triclosan in water). Furthermore, biotransformation products such as methyl-triclosan were also present in the biofilm, with levels up to 42% of the concentration of accumulated triclosan. The presence of C₆₀ did not involve relevant changes in the bioaccumulation and biotransformation of microcontaminants in biofilms, which showed similar patterns. Nevertheless, the study shows that a detailed evaluation of the partition of the organic microcontaminants and their transformation products in freshwater systems are important to better understand the impact of the co-existence of others microcontaminants, like carbon nanomaterials, in their possible routes of bioaccumulation and biotransformation.

Nodal FDG-PET/CT uptake influences outcome and relapse location among esophageal cancer patients submitted to chemotherapy or radiochemotherapy

PURPOSE

Our aim was investigate whether lymph node uptake is associated with survival and regional relapses, and relapse patterns with respect to the radiotherapy fields in esophageal cancer (EC).

MATERIALS AND METHODS

The FDG-PET/CT image datasets of 56 patients were analyzed. All patients underwent definitive or neoadjuvant radio/chemotherapy (RCT). All patients suffering from persistent or recurrent local/regional-only disease after RCT were considered for salvage resection. Patients with adenocarcinoma without metastatic disease were considered for planned resection (usually within 3 months of treatment).

RESULTS

Patients with PET-positive lymph nodes before treatment had a worse overall survival and a shorter disease-free survival than those without PET-positive nodes. They also had worse node and metastatic relapse-free survival. N2 patients had statistically significant poorer outcomes than N1-N0 patients and a better survival if the involved nodes were closer to the esophageal tumor. Involved node location by PET/CT also affected global, nodal and metastatic relapses. In addition, an increment of SUVmax value increased relative risk of death and increased relative risk of node and metastatic relapses. The first site of relapse was metastatic recurrence and, second, local recurrence. The most frequent were "in-field" loco/regional recurrence. We observed a relationship between patients classified-N1 and out-field nodal recurrence (p = 0.024), and between patients-N2 and in-field nodal recurrence. The number of PET-positive nodes was an independent significant prognostic predictor for relapse (p < 0.001).

CONCLUSION

Our study shows that only FDG-PET/CT can provide prognostic information in EC. Nodal PET/CT uptake influences outcome and relapse location among EC patients.

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.

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.

Fullerenes Influence the Toxicity of Organic Micro-Contaminants to River Biofilms

Organic micro-contaminants (OMCs) enter in freshwaters and interact with other contaminants such as carbon nanoparticles, becoming a problem of unknown consequences for river ecosystems. Carbon nanoparticles (as fullerenes C₆₀) are good adsorbents of organic contaminants and their interaction can potentially affect their toxicity to river biofilms. We tested the C₆₀ interactions with selected OMCs and their effects on river biofilms in different short-term experiments. In these, river biofilms were exposed to C₆₀ and three OMCs (triclosan, diuron, or venlafaxine) and their respective mixtures with fullerenes (C₆₀ + each OMC). The effects were evaluated on structural, molecular, and functional descriptors of river biofilms. Our results showed that C₆₀ did not cause toxic effects in river biofilms, whereas diuron and triclosan significantly affected the heterotrophic and phototrophic components of biofilms and venlafaxine affected only the phototrophic component. The joint exposure of C₆₀ with venlafaxine was not producing differences with respect to the former response of the toxicant, but the overall response was antagonistic (i.e., decreased toxicity) with diuron, and synergistic (i.e., increased toxicity) with triclosan. We suggest that differences in the toxic responses could be related to the respective molecular structure of each OMC, to the concentration proportion between OMC and C_60, and to the possible competition between C₆₀ pollutants on blocking the receptors of the biological cell membranes. We conclude that the presence of C₆₀ at low concentrations modified the toxicity of OMC to river biofilms. These interactions should therefore be considered when predicting toxicity of OMC in river ecosystems.

Multiple stressor effects on biological quality elements in the Ebro River: Present diagnosis and predicted responses

Multiple abiotic stressors affect the ecological status of water bodies. The status of waterbodies in the Ebro catchment (NE Spain) is evaluated using the biological quality elements (BQEs) of diatoms, invertebrates and macrophytes. The multi-stressor influence on the three BQEs was evaluated using the monitoring dataset available from the catchment water authority. Nutrient concentrations, especially total phosphorus (TP), affected most of the analyzed BQEs, while changes in mean discharge, water temperature, or river morphology did not show significant influences. Linear statistical models were used to evaluate the change of water bodies' ecological status under different combinations of future socioeconomic and climate scenarios. Changes in land use, rainfall, water temperature, mean discharge, TP and nitrate concentrations were modeled according to the future scenarios. These revealed an evolution of the abiotic stressors that could lead to a general decrease in the ecosystem quality of water bodies within the Ebro catchment. This deterioration was especially evidenced on the diatoms and invertebrate biological indices, mainly because of the foreseen increase in TP concentrations. Water bodies located in the headwaters were seen as the most sensitive to future changes.

Diatom responses to sewage inputs and hydrological alteration in Mediterranean streams

We analyzed the conjoint effects of sewage inputs and hydrological alteration on the occurrence of teratological forms and on the assemblage composition of stream benthic diatoms. The study was performed in 11 Mediterranean streams which received treated or untreated urban sewage (Impact sites, I), whose composition and morphological anomalies were compared to upstream unaffected (Control, C) sites. The impact sites had high concentrations of ammonium, phosphorus, and pharmaceutical compounds (antibiotics, analgesics, and anti-inflammatories), particularly in those receiving untreated sewage. Impact sites had a higher proportion of teratological forms as well as a prevalence of diatom taxa tolerant to pollution. The differences in the diatom assemblage composition between the paired C and I sites were the largest in the impacted sites that received untreated sewage inputs as well as in the systems with lower dilution capacity. In these sites, the diatom assemblage was composed by a few pollution-tolerant species. Mediterranean river systems facing hydrological stress are highly sensitive to chemical contamination, leading to the homogenization of their diatom assemblages.