Artificial water bodies are becoming more numerous, and their importance at both local and global scales is growing. As a result, understanding the changes in aquatic biodiversity across various spatial and temporal dimensions requires their consideration in any analysis. This study examines two cases that could potentially lead to a deeper comprehension of this. The first case. After gold mining, three dozen lakes formed along the Bol’shiye Koty River, which flows into Lake Baikal. The fauna of the river and artificial lakes was examined by the authors between 2022 and 2025. As a result, a total of 34 invertebrate species were found in the studied rivers, and 68 species in technogenic lakes. These lakes, as new habitats, have significantly boosted the local aquatic invertebrate richness. As the second case, the authors’ study on the North Crimean Canal plankton in 2022 was used. The canal was constructed to address the acute freshwater shortage in Crimea. It stretched 403 km, and its branches totaled over 10,000 km, significantly altering aquatic and terrestrial ecosystems in Crimea. Its construction created a new migratory route for species from the Dnieper River basin to the peninsula, also creating new types of aquatic habitats for them. Many species from various taxa have thrived in Crimea, establishing robust populations. The influence of various types of artificial water bodies differs significantly. Biodiversity preservation can have both positive and negative effects.
Andrey A. Chemagin, Elena I. Popova, Martin Schletterer
This study examines the dynamics and characteristics of seasonal fish migration into the floodplain of a large lowland river. For continuous recording of the number of fish migrating upstream and downstream, and their size composition, the hydroacoustic complex “NetCor” was used. The system was permanently installed in spring 2022 on a floating platform in the Varpak River (a small tributary of the Irtysh River), mounted in a side-scan setup from the left bank. The dominant role of water level and temperature for abundance dynamics of fish migrating into the floodplain is demonstrated. The earlier onset of high values for these factors positively correlate with the abundance of migratory fish. Their influence accounts for approximately 70%. On a daily basis, migration dynamics are determined by the daily variation in illumination. The abundance of upstream migrant fish correlated with diurnal variations in illumination. Migration intensity increases during periods preceding morning and, to a lesser extent, evening twilight. The lowest proportion of migratory fish was observed during the daytime, when illumination was highest. The influence of water temperature, water level and light on the dynamics of seasonal fish migration is revealed. At the same time, a number of specific features have been noted for seasonal migration to the floodplain: synchronous increases and decreases in the intensity of fish movements up and downstream are simultaneously recorded, while the general trend of migration to the floodplain is maintained; in the initial phase of the flood, the largest fish are the first to migrate into the floodplain, which is an adaptive behavioral response. The diurnal distribution pattern of migratory fish is a strategy which they use to counter visually oriented predatory fish species—zander, perch, and pike—to avoid optimal prey search conditions.
Sophie Mentzel, Jos van Gils, Merete Grung, Samantha Martins, Frederik Verdonck, Karel P. J. Viaene, Karel Vlaeminck, Anders L. Madsen, Luka Snoj, Gašper Šubelj, S. Jannicke Moe
The EU's Chemicals Strategy for Sustainability aims to incorporate environmental risk of combined exposure, stemming from unintentional chemical mixtures in the environment, into regulatory risk assessments. Within the ENCORE (ENvironmental CO-exposure and Risk Estimation) project, a probabilistic modeling framework was developed for assessing chemical risk to aquatic ecosystems at the watershed level across Europe. The developed probabilistic framework can synthesize multiple sources of information at EU level, as well as uncertainty in both exposure and hazard information. The framework builds upon a chemical exposure model originally used in the EU project SOLUTIONS for large-scale European domains, which is being further developed in ENCORE. More specifically, a workflow was developed for a Bayesian network (BN) model that can update prior probabilities of chemical exposure derived from process-based simulation (predicted exposure) data. Key data sources integrated into the BN included the pan-European publicly available dataset Waterbase Water Quality (WISE-6), from the Water Information System for Europe managed by the European Environment Agency (EEA). Bayesian updating is used to integrate this new evidence (chemical monitoring data) improving accuracy of risk calculation. A pilot study, using a subset of pesticides in Belgium, was selected to develop and test the implementation of this probabilistic approach using BNs. This pilot will serve as a proof-of-concept before this risk modeling approach is scaled up to larger European regions. The goal of this approach is to identify chemicals with high contribution to risk in the aquatic environment, by accounting for spatial exposure patterns in watersheds across large regions of Europe and temporal patterns across months.
Martin Janiga, Marián Janiga, Jakub Tuchyňa, Patrik Pánik, Zuzana Kompišová Ballová
High mountain streams are experiencing pronounced shifts in precipitation regimes and water chemistry; however, it remains unclear how organisms inhabiting these systems influence the transfer of chemical elements through food webs. We measured concentrations of potassium and chlorine in algae, grazing mayflies, predatory stoneflies, and Alpine Bullhead (Cottus poecilopus) across seasons in an alpine stream. Algae exhibited marked seasonal variation, with higher potassium accumulation during the main summer growth period despite relatively stable water concentrations. Grazing mayflies maintained stable potassium levels but showed increased chlorine during colder months when chlorine concentrations in water were elevated. Predatory stoneflies showed only minor seasonal variation, with a slight increase in potassium in winter. The Alpine Bullhead did not exhibit significant seasonal changes in potassium or chlorine accumulation in its skull. Following major flood events, potassium and chlorine concentrations tended to co-vary across trophic levels, whereas under baseflow conditions they often varied independently. These patterns suggest that different trophic groups regulate element accumulation according to their physiology, life history, and ecological roles. The decoupling of organismal and water chemistry indicates that environmental concentrations alone do not fully explain element distribution within alpine stream food webs. Our findings provide new insights into element dynamics and highlight the importance of biological mediation in high-mountain ecosystems under changing environmental conditions.
João Henrique Alliprandini da Costa, Jansen Zuanon, Amanda Selinger, Ursulla Pereira Souza, Rafael Mendonça Duarte
Temporary freshwater habitats are characterized by cyclical flooding and drying that create highly dynamic conditions for fish community assembly. These environments can exhibit high spatial and temporal variability in community structure driven by local topography, distance to source habitats and interannual variation in rainfall, which affects connectivity dynamics. As such, they provide unique opportunities to test hypotheses about the processes shaping metacommunities. Here, we investigate these processes in temporary freshwater habitats of the Atlantic Forest. We sampled 36 temporary pools and 36 roadside ditches throughout 2024, recording 1,545 individuals from 20 species. We tested if community composition differs between habitat type and rainfall periods and whether beta diversity components were associated with local environmental and spatial predictors. Fish community composition did not differ significantly between habitats or hydrological periods, but temporal variation in spatial beta diversity was consistently high and influenced by turnover. During the dry period, nestedness was positively correlated with differences in volume for temporary pools and roadside ditches. Additionally, during the wet period, turnover in ditches was correlated with differences in pH. In temporary pools during the wet period, turnover increased with differences in distance to the nearest stream. High turnover for both habitats and periods suggest spatial processes such as dispersal limitation and colonization history are key drivers of community structure in those temporary aquatic habitats. Nestedness correlations with differences in volume in the dry period indicate that greater habitat availability promotes species accumulation under low connectivity, where dispersal occurs possibly only by overland displacement. Meanwhile, turnover correlation with differences in pH for ditches in the wet period is consistent with mass effect dynamics under higher connectivity conditions, with pH acting as a proxy for stream water influx. Turnover correlation with differences in distance to the nearest stream for pools during the wet period suggest colonization by highly tolerant and capable of dispersal species in more isolated sites. Overall, our findings emphasize that beta diversity in temporary aquatic habitats is primarily structured by habitat availability and spatial processes interacting with hydrological dynamics, underscoring that effective conservation must target the entire floodable mosaic rather than isolated sites to maintain this dynamic metacommunity.
