Gayane Shahnazaryan

River ecosystems are increasingly vulnerable to intensified human pressures associated with population growth and rising living standards, leading to structural changes and altered ecosystem service (ES) provision. The lower course of the Hrazdan River (Armenia) exemplifies these impacts, as it flows through Yerevan, the capital city, and receives substantial inputs of largely untreated wastewater. To assess resulting changes in ES, this study applies a multi‐method approach combining field‐based ecological assessments with social survey research. This integrated framework enables the comparison of actual ES flows with stakeholder perceptions, capturing both biophysical conditions and societal values. Results reveal a marked discrepancy between perceived and actual ES provision. While regulating and maintenance services are relatively highly prioritised by stakeholders, many essential ecosystem functions remain poorly understood, indicating significant knowledge gaps and limited public engagement. At the same time, the availability and quality of key services are severely degraded, contributing to tensions between stakeholders and decision‐makers. These findings point to persistent management challenges, including mismatches between top–down governance and bottom–up engagement. The study highlights the importance of integrating ecological data with social perspectives to support more effective, inclusive and conservation‐oriented management strategies for heavily impacted river systems.

This study evaluates whether existing long-term monitoring data are sufficient to distinguish natural background concentrations from anthropogenic influences on chemical river water quality in Lake Sevan basin. A comprehensive dataset covering physicochemical parameters, nutrients, and trace metals was analyzed for nine major tributaries with different geological settings and land-use characteristics. Multivariate statistical analysis was applied to identify baseline conditions and deviations attributable to human activities. The results indicate that water chemistry is primarily controlled by lithology and hydrological regime, particularly in minimally impacted headwater regions. In contrast, elevated concentrations of nutrients (e.g., nitrate and phosphate) and selected trace elements were associated with agricultural runoff, urban discharge, and localized industrial inputs. Spatial patterns reveal clear gradients of increasing anthropogenic impact downstream and in densely populated sub-basins. The study also demonstrates that, while the current monitoring network is suitable for assessing the overall chemical status of rivers, it is less effective in defining natural background levels and quantifying individual pollution sources due to limited upstream reference conditions. Overall, this approach provides a scientific basis for improved water quality management and policy implementation in the Lake Sevan basin. The findings highlight the importance of integrating long-term monitoring data with statistical tools to support sustainable watershed management in vulnerable catchments.

Freshwater ecosystems are increasingly affected by anthropogenic stressors, necessitating the assessment of sensitive biomarkers of sublethal impact. This study assessed the seasonal variability of oxidative stress parameters in the amphipod Gammarus lacustris from three tributaries of Lake Sevan (Armenia)—the Gavaraget, Karchagbyur, and Argichi Rivers—with contrasting hydrophysical and hydrochemical conditions. During 2022–2024, lipid peroxidation (MDA), antioxidant enzymes (CAT, SOD, GR, and GST), and glutathione (GSH) were measured in specimens collected in May, July, and October and related to temperature, dissolved oxygen, nutrients, major ions, and trace elements. Biomarker levels generally increased from spring to summer and declined in autumn, following temperature and photoperiod patterns. Statistically significant seasonal dynamics were most consistent in the Karchaghbyur River, while, in the Gavaraget and Argichi Rivers, they varied by biomarker and year. Amphipods from the Gavaraget River exhibited consistently elevated levels of oxidative stress biomarkers, consistent with elevated nutrient concentrations and stronger anthropogenic impacts. A short-term increase in all biomarkers in the Argichi River in 2023 indicated episodic acute stress. Overall, the response of oxidative stress biomarkers in G. lacustris reflected both the natural seasonal variability and spatial differences in environmental pressure, confirming their potential as a tool for monitoring Lake Sevan’s tributaries.

The UN framework of “Integrated Water Resources Management” recommends countries establish a sustainable management of their water resources, which relies on the availability of proper assessment indexes for the ecological status of surface waters. Such indexes have been developed by many EU countries under the EU Water Framework Directive. Non-EU countries may be interested in adapting such assessment tools. Hence, we describe here a test of three macrophyte-based assessment tools developed in EU countries for use in Armenia. All three indices were tested in a regionally adapted version where local species were entered into reference taxonomic lists, river types were assigned, and matching exercises of the results with benthic macroinvertebrates and physical and chemical parameters of the rivers were performed. The results show that the three tested assessment tools produced similar spatial patterns of ecological status changes, while the adapted version of the MTR index had the highest number of significant correlations with various metrics of macrozoobenthos and hydro-chemical parameters. We conclude that assessment scores for rivers based on macrophytes can be used for rivers of the Caucasus after regional adaptation of the reference macrophyte list. We recommend that the modified MTR index be introduced into the national hydrobiological system of Armenia after some additional adaptations.

Lake Sevan is the second largest high-mountain lake in the Caucasus, with economic, historical and cultural significance. During the study period of 2015–2019, a total of 209 species of algae and cyanobacteria from eight taxonomic divisions were identified in the phytoplankton of Lake Sevan. Among them, diatoms increased their presence during the study period. The abundance and biomass values increased during the study period, while bloom outbreaks occurred with greater frequency. The Dolichospermum cyanobacterial species causing bloom in the summer, releasing toxins, were noted as posing a threat to the rational use of Lake Sevan. The species number in Big Sevan was generally lower than in Small Sevan. The simultaneous decrease in species richness during the study period from 2015 to 2019 from 53 to 40 species, the Shannon Index from 0.61 to 0.06 and the Saprobic Index from 2.00 to 1.73 reveals a tendency towards restructuring of the ecosystem of Lake Sevan towards simplification. In combination with an increase in quantitative indicators of phytoplankton and the number of species of eutrophic state indicators, these dynamics show an increase in the imbalance of the ecosystem. Redundance Discriminant analysis indicates an increase in water pH and copper concentration as negative factors, and an increase in the total ionic composition and temperature as factors stimulating the development of phytoplankton. Statistical maps revealed points on the coast of Lake Sevan responsible for factors influencing its ecosystem according to various variables, including copper influx. The analysis also revealed sufficient capacity of the ecosystem of Lake Sevan for self-purification during the study period. For the first time, 99 species of diatoms and cyanobacteria with IUCN categories were identified for Lake Sevan, seven of which are considered threatened. The number of threatened species of categories CR and EN decreased between 2015 and 2019, indicating adverse impacts on sensitive ecosystem species. An assessment of the changes occurring in Lake Sevan indicates the need to continue hydroecological monitoring in combination with bioindication and statistical methods and an inventory of all factors affecting the stability of the ecosystem of the high-mountain Lake Sevan.

The narrow-clawed crayfish is a crayfish species that was accidentally introduced into the ecosystem of Lake Sevan in the 1980s. Soon it became one of the most preferred fisheries in the lake and an important link in the food chain by successfully replacing the endemic fish subspecies Sevan khramicarp (Capoeta sevangi, De Filippi, 1865) in the chain of detritivores. However, recently, the stock declines dramatically, associated with two main threats: the impact of burn-spot disease and an increase in fishing pressure on its population. To estimate the state of population under multiple stress conditions, we investigated the dynamics of stock, the size/age and sex structure, the fecundity, and the health status of the population. A comparative analysis of oxidative stress biomarkers (superoxide dismutase, catalase, glutathione-S-transferase activities and reduced glutathione, thiobarbituric acid reactive substance contents) showed significant differences between healthy and infected individuals. Another indirect effect of the disease, which probably leads to a decrease in the stock, was an increase in the proportion of immature females. Also, we observed some decrease in the infection rate along with the decline in the density of crayfish. However, stock reduction and some changes in the population may also be caused by a strong bloom of cyanobacteria.

Lake Sevan, a large, deep, alpine lake in the Lesser Caucasus is the focus of this Special Issue of the Journal of Limnology. It was an outstanding ecosystem 100 years ago characterised by excellent water quality, rich biodiversity with a high level of endemism, wide-ranging beds of macrophytes along the shores and a productive and sustainable fish production. Due to its beauty, natural history, and contributions to social and economic welfare it is also a cultural heritage for the Armenian Nation including its large diaspora.

Lake Sevan (Armenia) is one of the large freshwater high-mountain lakes of Eurasia. Detailed information about the extent and fate of trace elements on lake sediment and water quality has not been published yet. For this reason, surface sediment and water samples were collected from the southern and northern basins of Lake Sevan to determine trace element concentrations and assess the trace element behaviour. Geo-accumulation index, potential ecological risk index, and hazard index were calculated to estimate the environmental risk potential. In comparison to reference values, the investigated sediment samples contained elevated concentrations frequently for V, Cr, Co, Ni, Mo, Cd, Be, Ti, Rb, Sr, Se, Hf, and Th and occasionally for Cu, As, Li, B, Ag, Sb, Tl, Bi, U, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Tm. An overall potential ecological risk posed by all the investigated trace elements in the sediments was assessed to be moderate-considerable, however, Mo, Hg, and Cd were the elements with the highest ecological risk potential. The two basins of the lake showed significantly different behaviour according to the investigated trace element contents in the sediments to be higher in the bigger basin compared to the smaller basin. In comparison to reference concentrations in water samples according to the use of the adapted geo-accumulation index, elevated values for Ti, Cr, Cu, Cd, and Pb were observed. Elevated concentration was also observed in the case of B in nearly all water samples in comparison with literature values. Nevertheless, several water samples can be seen as not strongly anthropogenic influenced by Co, Ni, Sn, Sb, Ag, Hg, and Bi. The concentrations of trace elements in the lake water caused health risks to humans particularly children in the case of lake water used for drinking purposes, moreover, As was the main element posing health hazards. The results point out further attention to the sources of elevated trace elements in Lake Sevan, including anthropogenic influences and geological characteristics.

The objective of this research is to assess the distribution of heavy metals in the waters and sediments of the Voghji River and its tributaries impacted by mining activity and to reveal the real source of each of the heavy metals in the environment for assessing the pollution level of heavy metals. Voghji River with two main tributaries (Geghi and Norashenik) drain two mining regions. To identify distribution and pollution sources of heavy metals, the water and sediment samples were collected from eight sampling sites. The results of statistical analysis based on data sets of the period 2014–2016 showed that, after the influence of drainage water and wastewater of mining regions, heavy metal contents in the Voghji River basin dramatically increased. The waters of the Voghji River were highly polluted by Mn, Co, Cu, Zn, Mo, Cd, and Pb. The relation of metals content was highly changed due to anthropogenic impact disturbing the geochemical balance of the Voghji River. The water quality based on only heavy metal contents in the source of the Voghji River belongs to “good” chemical status, and in the sources of Geghi and Norashenik Rivers it is “moderate.” The water quality of Voghji and Norashenik Rivers is sharply worsening after the influence of mining activity, becoming “bad” chemical status. The research revealed the pollution sources of each metal.