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The EU and the international community is realising that the Water, Energy, Food and Ecosystem components are interlinked and require a joint planning in order to meet the daunting global challenges related to Water, Energy and Food security and maintaining the ecosystem health and in this way, reach the SDGs. If not dealt with, the world will not be able to meet the demand for water, energy and food in a not too far future and, in any case, in a not sustainable way. The strain on the ecosystems resulting from unsustainable single-sector planning will lead to increasing poverty, inequality and instability. The Nexus approach is fully aligned with and supportive of the EU Consensus on Development. Key elements of the Consensus will require collaborative efforts across sectors in ways that can be supported/implemented by a Nexus approach. In this way, transparent and accountable decision-making, involving the civil society is key and common to the European Consensus on Development and the Nexus approach. The Nexus approach will support the implementation of the SDG in particular SDG 2 (Food), SDG 6 (Water) and SDG 7 (Energy), but most SDGs have elements that link to food, water and energy in one or other way, and will benefit from a Nexus approach. The SDGs are designed to be cross-cutting and be implemented together, which is also reflected in a WEFE Nexus approach. A Nexus approach offers a sustainable way of addressing the effects of Climate Change and increase resilience. The WEFE Nexus has in it the main drivers of climate change (water, energy and food security) and the main affected sectors (water and the environment). Decisions around policy, infrastructure, … developed based on the WEFE Nexus assessments will be suitable as elements of climate change mitigation and adaptation. In fact, it is difficult to imagine solutions to the climate change issue that are not built on a form of Nexus approach. The Nexus approach is being implemented around the world, as examples in the literature demonstrate. These examples together with more examples from EU and member state development cooperation will help build experience that can be consolidated and become an important contribution to a Toolkit for WEFE Nexus Implementation. From the expert discussions, it appears that because of the novelty of the approach, a Toolkit will be an important element in getting the Nexus approach widely used. This should build on experiences from practical examples of NEXUS projects or similar inter-sectorial collaboration projects; and, there are already policy, regulation and practical experience to allow institutions and countries to start applying the Nexus concept., JRC.D.2-Water and Marine Resources

The increase of antibiotic resistance against antibiotics (AB) is an alarming phenomenon threatening the human well being and heading back to the pre-antibiotic era where many infectious diseases may become again untreatable with antibiotics. There is a strong correlation between AB use and occurrence of resistances which suggests anthropogenically-driven environments as reservoirs of antibiotic resistant bacteria (ARB). Among anthropogenically - driven environments, wastewater treatment plants (WWTPs), have been linked with the increased incidence of pathogens and ARB in freshwater ecosystems. Principal goal of the study was to evaluate the role of WWTPs as environmental reservoirs for antibiotic resistance and pathogenic bacteria. In this thesis, classical and molecular microbiology methods were applied to analyse resistance levels of bacterial communities from wastewater and wastewater-polluted environments at different geographical locations of developed (German and Switzerland) and developing (Nigeria) countries. Additionally, a novel approach which makes use of a combination of quantitative genomics, Next Generation Sequencing and drug-related health data was applied to quantitatively detect antibiotic resistance genes (ARG) in wastewater and assess their seasonal dynamics. The relative abundance of ARG was not reduced by the WWTPs in the treated effluent. Effluents were responsible for significantly high levels of ARB and ARG in the receiving environment because capable of introducing and/or selecting ARB carrying ARG on genetic mobile elements. The ARG levels differed between seasons independently from the water sanitation. High ARG levels were displayed in autumn and winter in coincidence with the higher uptake of antibiotics by the outpatients of the municipality.Contrary to the ARG, the abundance of bacteria was reduced by WWTPs processes in the effluent of developed countries. The WWTPs were also responsible for the changes of the microbial community from the wastewater to the effluent. Contrary to developed countries, the poor treatment of wastewater in Nigeria facilitated the spread of multi-drug resistant pathogens in the freshwater ecosystem. These bacteria were also carriers of clinically relevant ARG contributing to the accumulation of multiresistant pathogens in the environment. All in all, this thesis shows that well established WWTP technologies are not capable to prevent or reduce the abundance of ARG in the freshwater ecosystem and poorly treated wastewater enriches the environmental reservoirs of ARG. Antibiotic resistance can spread across taxonomically distant bacteria and therefore explain the strong dispersal of ARG in wastewater effluents. These results show that antibiotic resistances are also ubiquitous in the freshwater environment and that anthropogenically - driven environments determine the incidence of antibiotic resistance. As for the clinic, tackling the problem of antibiotic resistance in the environment is fundamental. Without any action, the environmental reservoirs of resistance will increase and therapeutic failure in the clinic will irreversibly compromise the biggest progress in medicine of the 20th century.

At present, very little is known about the fate and perseverance of multiresistant bacteria and their resistance genes in natural aquatic environments. Treated, but partly also untreated sewage of the city of Lausanne, Switzerland is discharged into Vidy bay (Lake Geneva) resulting in high levels of contamination in this part of the lake. In the present work we have studied the prevalence of multiresistant bacteria and resistance genes in the wastewater stream of Lausanne. Samples from hospital and municipal raw sewage, treated effluent from Lausanne’s wastewater treatment plant (WTP) as well as lake water and sediment samples obtained close to the WTP outlet pipe and a remote site close to a drinking water pump were evaluated for the prevalence of multiresistant bacteria. Selected isolates were identified (16S rRNA gene fragment sequencing) and characterized with regards to further resistances, resistance genes, and plasmids. Mostly, studies investigating this issue have relied on cultivation-based approaches. However, the limitations of these tools are well known, in particular for environmental microbial communities, and cultivation-independent molecular tools should be applied in parallel in order to take non-culturable organisms into account. Here we directly quantified the sulfonamide resistance genes sul1 and sul2 from environmental DNA extracts using TaqMan real-time quantitative PCR. Hospital sewage contained the highest load of multiresistant bacteria and antibiotic resistance genes. Wastewater treatment reduced the total bacterial load but evidence for selection of extremely multiresistant strains and accumulation of resistance genes was observed. Our data clearly indicated pollution of sediments with antibiotic resistance genes in the vicinity of the WTP outlet. The potential of lakes as reservoirs of multiresistant bacteria and potential risks are discussed.