Mediterranean freshwater systems face the lack of water as an important threat along with other multiple stressors (e.g., eutrophication, salinization, changes in hydrology and morphology) mainly attributed to human intervention. These stressors have been maximized due to the climate variability, the progressive diminishing of freshwater availability and the topography characteristics. Lake Karla is an example of a lake ecosystem which was dried in the 1960s and now is restored, facing various anthropogenic pressures. During the last 2 years (2010–2012) a ‘new’ shallow lake was reconstructed experiencing extensive alterations associated with land use changes, hydrological flow modifications, over-enrichment of chemicals, inappropriate management of biological resources. In terms of conservation value, Lake Karla is listed in Natura 2000 sites as a protected area. The aim of the present paper is to identify the key-descriptors highlighting the function of the new system, thus providing necessary ‘tools’ for an effective management plan. A 12-month monitoring study has taken place revealing the hydrological profile, the excess of in-lake nutrient concentrations, mainly attributed to the inflows and surface runoff, thus promoting a cultural eutrophication as it is also expressed by the high chlorophyll values. Relationships between nutrients and chlorophyll-a concentrations highlight the system’s functioning. Yet, the classification of Lake Karla, as a highly modified water body, according to the Water Framework Directive, is discussed. Lake Karla serves as a paradigm on the multiple stressor effects and the complexity of biological restoration even though physical restoration has been established.

The evaluation of effluent wastewater quality mainly relies on the assessment of conventional bacterial indicators, such as fecal coliforms and enterococci; however, little is known about opportunistic pathogens, which can resist chlorination and may be transmitted in aquatic environments. In contrast to conventional microbiological methods, high-throughput molecular techniques can provide an accurate evaluation of effluent quality, although a limited number of studies have been performed in this direction. In this work, high-throughput amplicon sequencing was employed to assess the effectiveness of chlorination as a disinfection method for secondary effluents. Common inhabitants of the intestinal tract, such as Bacteroides, Arcobacter and Clostridium, and activated sludge denitrifiers capable of forming biofilms, such as Acidovorax, Pseudomonas and Thauera, were identified in the chlorinated effluent. Chloroflexi with dechlorination capability and the bacteria involved in enhanced biological phosphorus removal, i.e., Candidatus Accumulibacter and Candidatus Competibacter, were also found to resist chlorination. No detection of Escherichia indicates the lack of fecal coliform contamination. Mycobacterium spp. were absent in the chlorinated effluent, whereas toxin-producing cyanobacteria of the genera Anabaena and Microcystis were identified in low abundances. Chlorination significantly affected the filamentous bacteria Nocardioides and Gordonia, whereas Zoogloea proliferated in the disinfected effluent. Moreover, perchlorate/chlorate- and organochlorine-reducing bacteria resisted chlorination.

Rural abandonment and associated rapid urbanization, agricultural intensification, and climate change have been key factors transforming terrestrial landscapes, with significant impacts on the environmental quality and the ecosystem services (ES) provided to human welfare. In this study, two understudied rural river basins located in Thrace, North Greece, were selected to assess changes in landscape pattern, composition, and eco-environmental quality and ecosystem services values (ESV). Cloud-based remote sensing (RS) analyses of multitemporal Landsat imagery in the Google Earth Engine (GEE) platform were applied for multitemporal land use/land cover changes (LULCC) quantification between 1984–2021, along with landscape pattern, eco-environmental quality, and ES assessment. Although ecosystem changes observed were not extensive over this period, eco-environmental quality appeared to be affected due to fragmentation. Preserving the ecosystem’s naturalness can enhance cultural ES to avoid further values loss originating from provisioning ES exploitation. This study highlights the strong connection between landscape configuration and eco-environmental quality, emphasizing the strong impact that anthropogenic activities have on the environment. The monitoring of the effects of LULCC on ecosystem health and the economic value of ES is crucial for the introduction of spatial planning and restoration policies.

The ecosystem services (ES) concept is embedded in all new European directives but its integration in the Water Framework Directive (WFD) is absent, despite the latter being the major legislative tool. The research aims to assess the knowledge of ES that lies within the River Basin Management Plans (RBMPs) in Greece so as to further depict their representation in the relevant planning tools, to support policy making and express the implementation experience to Member States for assisting EU reloading processes. The information on the ES’ status was extracted by the official RBMPs, processed and grouped following Common International Classification of Ecosystem Services (CICES) classification. The prioritization of ES included in the programs of measures (PoMs) further showed the targeting for each River Basin District (RBD). The results were not homogenous for the RBDs, revealing different needs in measures and indicating there is a lack in “communication” between the relevant EU and national regulations. Moreover, a wide suite of water-related ES is hindered in addressing multiple benefits coming from provisioning, regulating and cultural ES. For a proper WFD reload and continuation, the infusion of the ES concept and prerequisites in its objective, and the reviewing of the RBMPs’ target and the suggestion of integrated PoMs are necessary steps that could deliver added value in such legislation.

Bacterial communities, microbial populations, and antibiotic resistance of potential pathogens in the water and fish (Cyprinus carpio, flesh and gut) from different areas (A1, A2 and A3—A1 was linked with river water, A2 with cattle activity, and A3 with waters of a spring after heavy rains) of Lake Karla (Thessaly, Central Greece) were investigated. The isolated bacteria were identified using Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) and were tested for resistance in 21 antibiotics. The microbiota composition of fish flesh was also studied using 16S amplicon-based sequencing Serratia fonticola and several species of Aeromonas (e.g., Aeromonas salmonicida, Aeromonas bestiarium, Aeromonas veronii, etc.) exhibited the highest abundances in all studied samples, while the microbiota profile between the three studied areas was similar, according to the culture-dependent analysis. Of them, S. fonticola was found to be resistant in the majority of the antibiotics for the water and fish (gut and flesh), mainly of the areas A1 and A2. Regarding 16S metabarcoding, the presence of Serratia and Aeromonas at genus level was confirmed, but they found at very lower abundances than those reported using the culture-dependent analysis. Finally, the TVC and the rest of the studied microbiological parameters were found at acceptable levels (4 log cfu/mL or cfu/g and 2–4 log cfu/mL or cfu/g, extremely low levels of E. coli/coliforms) in both water and fish flesh. Based on our findings, the water of Lake Karla would be used for activities such as irrigation, recreation and fishing, however, the development and implementation of a quality management tool for Lake Karla, to ensure environmental hygiene and prevention of zoonosis during the whole year, is imperative.