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Background: Climate changes influence the ecosystems and induce potential risks regarding the natural products and services; the human society should predict and adapt in time to these coming global challenges. This research highlights a possible fragmentation of some of the Lower Danube River Basin lentic ecosystems fish populations in a climate change scenario. Results: The studied climate change potential events will affect 18 fish species of economic interest and eight of conservation interest and will induce disorder in some of the Lower Danube specific type of fish communities. The studied area was identified as a significant hot spot regarding the fish fauna ecological status major hazard, in a possible climate change (heating-drought-water depth decreasing) sequence of potential future events. Primarily the southern lakes of the studied area can be negatively influenced by the decreasing of the lakes water quality and quantity, some of the spawning habitats will vanish, some habitats and species will disappear, suspended sediment and nutrient levels in water will increase, eutrophication phenomenon will increase, the hydrological connectivity will diminish, fish associations' structure will significantly change, etc. Conclusions: The climate changes trend in the Lower Danube Basin will affect the studied lakes ecological state and associated fish communities; mitigating measures are urgently needed. The future potential relative isolation of researched lakes by the surrounding hydrographical nets, for safety reasons of human communities or to convert inland areas should be banned specially for the lakes: Balta Domnească,

Non-ferrous metals mining activities have long accompanied people, and began in the study area of South East Europe over 2000 years ago. The environment quality is significantly affected by both historic mining activities and contemporary impacts. All these problems, inducing synergic negative effects on local organism communities, have created a chronic state of pollution. The Corna Valley has one of the oldest historical human impacts in Romania due to the influence of mining. Fish and benthic macroinvertebrates have exhibited significant responses to long term mining effects on lotic systems. The analysis of macroinvertebrate communities, correlated with the lack of fish and some biotope characteristics, indicates that the Corna River presents a variety of categories of ecological status between sectors. The lack of fish reveals the poor ecological conditions. Technical and management solutions are proposed here to diminish the historical environmental problems and to avoid future ecological accidents, especially in an attempt to improve any construction plan concerning a possible new de-cyanidation dam and lake. Fish and benthic macroinvertebrates have exhibited significant responses to long term mining effects on lotic systems. Two management zones were identified, an upper zone which can be used as a reference area and a lower zone, where pollution remedial activities are proposed.

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Background: The Mureș River Basin is a long-term heavily polluted watershed, in a situation of climate changes with decreasing water flow and related decreasing dilution capacity. Here, a mixture of emerging pollutants such as pharmaceuticals were targeted to reveal potential risks regarding the natural lotic ecosystems. Due to the continuous discharge into the environment, pharmaceuticals are gaining persistent organic pollutant characteristics and are considered emerging pollutants. Based on the hazard quotient, this research highlights the dangerous concentrations of carbamazepine, ibuprofen, furosemide, and enalapril in river water. Results: High levels of four pharmaceutical compounds (carbamazepine, ibuprofen, furosemide, and enalapril) and some of their derived metabolites (enalaprilat, carboxyibuprofen, 1-hydroxyibuprofen, and 2-hydroxyibuprofen) were reported in our study in the Mureș River Basin. Overall, pharmaceutical concentrations were found to be highest in the wastewater treatment plant (WWTP) effluent, median downstream of the WWTP, and lowest upstream of the WWTP, as was expected. For all pharmaceutical compounds tested, we recorded concentrations above the limit of quantification (LOQ) in at least one of the sites tested. Carbamazepine exhibited the highest mean values upstream, downstream, and at the WWTP. As expected, the highest concentrations for all the studied pharmaceutical compounds were detected in the WWTP effluent. All Hazard Quotient (HQ) values were below one (on a logarithmic scale in base 10), with the highest values in the WWTP and the lowest in the river upstream of the WWTP. The HQ intervals were in the same range for furosemide, carbamazepine, and ibuprofen at each of the three different sites: upstream WWTP effluent, and downstream. The interval for enalapril stands out as having the lowest HQ at all three sites. Conclusions: Based on these results, the large and complex hydrographical system Mureș River Basin was transformed from a grey area, with little information about pharmaceutical contamination, to a hotspot in terms of contamination with emerging pollutants. Pharmaceutical compound concentrations were found to be the highest in WWTP effluents. The WWTP effluent concentrations were among the highest in Europe, indicating that treatment plants are the primary source of water pollution with pharmaceuticals compounds. The detected levels were higher than the safety limit for carbamazepine and ibuprofen. The determined HQ values imply that the measured levels do pose a threat to the environment for the studied pharmaceuticals. Based on the obtained results, human communities can assess, monitor, predict, and adapt in time to these already-present regional challenges and risks for sustainable use of natural resources, including water and associated products and services.