Limnological Review doi: 10.3390/limnolrev26030048

Authors: Anna Szafarczyk Małgorzata Ulmaniec

This article discusses the use of thermal and mineral waters in Poland in balneology, rehabilitation, and recreation. It highlights their importance for health, economy, and tourism, as well as the country’s significant hydrogeothermal potential, particularly in the Carpathians, the Sudetes, and the Polish Lowlands. The authors present a classification of waters, their chemical and thermal properties, and their main applications: therapeutic baths, drinking cures, inhalations, peloidotherapy, and hydrotherapy. A significant portion of the study reviews the latest global research confirming the effectiveness of balneotherapy in the treatment of musculoskeletal and skin disorders, indicating the need for further clinical research. The paper also discusses Polish spas and recreational centers using thermal waters, pointing to their growing role in health care and wellness tourism. Limitations to the development of balneotherapy, such as high drilling costs, geological risks, and the need to maintain therapeutic water parameters, are highlighted.

Limnological Review doi: 10.3390/limnolrev26030047

Authors: Peter Sanful Radoslav Smolak Solomon Amfoh Asha Damoah

Climate warming can alter lake zooplankton through changes in thermal structure, oxygen availability, nutrient cycling, and phytoplankton dynamics, but decadal evidence from African lakes remains scarce. We compared zooplankton size structure and biomass in Lake Bosumtwi, Ghana, between 2005–2006 and 2018–2020, using harmonised historical data and recent observations of zooplankton, temperature, dissolved oxygen, nutrients, chlorophyll a, and water transparency. Water temperatures increased across all depth strata, with the largest increase in the epilimnion (+0.30 °C), while dissolved oxygen declined by approximately 27%. Epilimnetic total nitrogen, total phosphorus, and chlorophyll a increased, and water transparency decreased. Chlorophyll a rose by 142% between periods, while mean total zooplankton biomass increased 2.33-fold, mainly because of higher copepod biomass. Mean body length decreased in nauplii but increased in copepodites and adult copepods, indicating contrasting stage-specific shifts in size structure. The median zooplankton biomass-to-chlorophyll a ratio increased from 59.46 to 79.24 (Mann–Whitney U = 210, p = 0.032). Biomass differed significantly among years for copepods, rotifers, and total zooplankton, but not for cladocerans. These findings show that warmer and less oxygenated conditions with higher chlorophyll a concentrations were accompanied by a substantial increase in copepod-dominated biomass and stage-specific changes in zooplankton size structure.

Limnological Review doi: 10.3390/limnolrev26030046

Authors: Mitzi Cubilla-Montilla Marisela Castillo Gonzalo Carrasco Carlos A. Torres-Cubilla

Chlorophyll-a is a widely used indicator for assessing the trophic status and water quality of aquatic ecosystems because of its close relationship with phytoplankton biomass. This study aimed to identify the physicochemical, biological, and temporal variables associated with chlorophyll-a concentrations in Lake Gatun during the 2017–2023 period using the Light Gradient Boosting Machine (LightGBM) algorithm and a Generalized Linear Model (GLM). A total of 25 predictor variables describing water quality were analyzed using data collected from 14 monitoring stations distributed throughout Lake Gatun within the Panama Canal watershed. The LightGBM model achieved satisfactory predictive performance, with an RMSE of 4.58, an MAE of 3.26, and a coefficient of determination (R2) of 0.42 on the testing dataset. Variable importance analysis identified turbidity, dissolved oxygen, and water transparency as the most influential predictors of chlorophyll-a concentrations. These findings improve our understanding of the factors associated with chlorophyll-a variability and demonstrate the potential of machine learning models as decision-support tools for monitoring and managing aquatic ecosystems.

Limnological Review doi: 10.3390/limnolrev26030045

Authors: I Kade Alfian Kusuma Wirayuda Abd Rahman As-syakur Martiwi Diah Setiawati Tri Atmaja Herlambang Aulia Rachman

Tropical lake ecosystems are vulnerable to degradation due to climate change and anthropogenic pressure. These dual pressures lead to ecological change and alterations in aquatic parameters, including chlorophyll-a (Chl-a). Lake Poso is the third-largest lake in Indonesia; Chl-a variability and phenology in this tropical lake remain understudied due to brief observational records. This study characterizes the spatiotemporal variability and phenology of Chl-a in Lake Poso, Indonesia, over two decades (2003–2025) to establish a multi-decadal baseline and detect early indications of increasing phytoplankton biomass. Chl-a was derived from combined Terra and Aqua MODIS observations processed in Google Earth Engine, followed by trend, phenological, and spatial analyses. Results reveal a significant increase in annual Chl-a and a general upward tendency across the study period. Climatological reconstruction identifies a distinct bimodal phenology, with a primary peak in December and a secondary peak in April. Interannual trends show no significant shift in Start of Season timing; however, primary peak magnitudes tend to increase (+0.079 mg m−3 yr−1), largely influenced by extreme episodic anomalies. Spatial analysis reveals heterogeneous increases in Chl-a, particularly in the central and northern zones. These findings suggest a possible early trajectory toward higher phytoplankton biomass and establish the first satellite-derived multi-decadal Chl-a baseline for Lake Poso.

Limnological Review doi: 10.3390/limnolrev26030044

Authors: Mila Chilikova-Luvomirova

Natural floods are unusual extreme events resulting from significant or prolonged rainfall, which sometimes turn into disasters. Trends indicate that these phenomena may become more frequent in the future. Therefore, many solutions are being implemented in practice to deal with the problem. In the European Union, enhanced measures have been taken, including the assessment and mapping of flood risks, triggered by the adopted legislation. Despite these solutions, flood disasters continue to occur, even in areas included in Flood Risk Management Plans but outside the territories designated as vulnerable. To investigate the reason, a study was conducted accounting for flood genesis and the role of flood debris and anthropogenic waste as a factor that can worsen the harmful impact of these events. It was considered whether there is a gap in the application of current methods and legislation. A brief review was performed concerning the physical description of the phenomenon and the evaluation methods used, accounting for the role that debris and anthropogenic waste play in them. Some main practices and applicable tools were also discussed in brief. As an illustration of the impact, a case study of a recent significant flood in Bulgaria was also presented. This flood affected an area that is not identified as at risk under the Flood Risk Management Plans developed in accordance with the European and Bulgarian legislation and requirements. The information presented here confirms the significant role that debris and anthropogenic waste play in the process of turning a flood into a disaster and highlights the need for additional work concerning their proper incorporation in both the regulation and assessment processes.

Limnological Review doi: 10.3390/limnolrev26030043

Authors: Bülent Akar Utku Avci

Blanket bogs are ombrotrophic peatlands where water is mainly supplied by precipitation. This study reports new algal records from blanket bogs in Türkiye, contributing to the knowledge of Türkiye’s freshwater algal flora. Algal samples were collected from five different blanket bogs located in the Eastern Black Sea Region of Türkiye. Samples were obtained on a monthly basis during selected months, May, July, and September in 2021, May and September in 2022, and July in 2023. A total of 50 taxa belonging to 19 genera were identified: Scytonema (1), Cavinula (1), Kobayasiella (1), Netrium (4), Closterium (3), Actinotaenium (5), Cosmarium (3), Euastrum (3), Micrasterias (2), Spondylosium (1), Staurastrum (15), Staurodesmus (2), Tetmemorus (2), Microspora (1), Characium (1), Desmodesmus (1), Trachelomonas (2), Calycimonas (1), and Opisthoaulax (1). Calycimonas and Opisthoaulax are reported as new genera for the freshwater algal flora of Türkiye. The identified taxa were predominantly observed in acidic, oligotrophic and low-conductivity waters, thereby indicating the distinctive ecological characteristics and conservation value of alpine blanket peat bogs.

Limnological Review doi: 10.3390/limnolrev26030042

Authors: Astried Sunaryani Prayatni Soewondo Arianto Budi Santoso Suharyanto Diana Rahayuning Wulan Sulung Nomosatryo Aldiano Rahmadya

Eutrophication in tropical endorheic lakes often persists despite reductions in external nutrient inputs, indicating an important role of internal nutrient loading. However, integrated evidence linking thermal stratification, sediment characteristics, and sediment-derived nutrient release in tropical endorheic lakes remains limited. This study investigated the mechanisms contributing to eutrophication in Lake Batur, a tropical endorheic volcanic lake in Indonesia, through seasonal water-column observations, sediment porewater profiling, diffusive nutrient flux analysis, and sediment characterization. Seasonal observations showed thermal stratification accompanied by hypoxic to anoxic bottom waters, while sediment-derived nutrient flux was dominated by ammonium and phosphate under reducing conditions. Sediment characterization at the representative sampling site revealed mineral assemblages dominated by biogenic silica, aluminosilicate clays, carbonates, and iron-bearing phases that may influence nutrient mobility under low-oxygen conditions. The results indicate strong coupling between thermal stratification, hypolimnetic oxygen depletion, and sediment–water interactions, suggesting that internal loading contributes to maintaining eutrophic conditions in Lake Batur. The endorheic nature of the lake likely enhances nutrient retention because of limited hydrological flushing and prolonged nutrient residence times. These findings improve understanding of eutrophication processes in tropical endorheic volcanic lakes and highlight the importance of considering sediment-derived internal loading together with external nutrient reduction in lake restoration strategies.

Limnological Review doi: 10.3390/limnolrev26030041

Authors: Christopher R. Mattheus

This paper addresses the geomorphic response of an engineered Chicago beach to a >1.5 m rise in Lake Michigan’s base water level, from 2013 to 2020. Topographic monitoring data acquired since 2012 and subsurface geophysical data collected in 2022 are integrated to explore the roles of lakefront infrastructure and beach topographic development on sedimentary dynamics, beach morphologic development, and stratigraphic architecture. While conceptual models of coastal geomorphology infer upward and landward beach-profile translation with lake-level rise, a high degree of along-shore variance occurs within pocket beaches. This stems from infrastructure-related modifications of storm hydrodynamics and scour patterns, close to shore, and backshore terrain physiography. The studied beach evolved contrary to how regional littoral drift patterns would have suggested, with erosion most severe along the embayment’s downdrift end, a product of infrastructure-induced scour and the reduced capacity for sediment retention through overwash accretion. Documented geomorphic patterns with lake-level rise are manifested in subsurface imaging data from the lake-level highstand, accordingly, providing a guide to more regional paleo-reconstruction. Great Lakes urban pocket beaches buffer shoreline infrastructure, offer recreational terrains, and support dune ecosystems of value to migrating shorebirds. Understanding their geomorphology benefits coastal managers looking to mitigate impacts of future climate and lake-level change.

Limnological Review doi: 10.3390/limnolrev26030040

Authors: Danijela Vukoičić Dragan Petrović Ljiljana Mihajlović Dušan Kićović Dušan Ristić

Lakes represent valuable natural resources with significant potential for sustainable tourism development. Their tourism valorization requires a comprehensive assessment framework that integrates environmental, infrastructural, socio-economic, and governance dimensions. This study applies the Fuzzy TOPSIS method to evaluate the sustainable tourism potential of ten selected lakes in Serbia. A multi-criteria framework was developed based on ten indicators, including water quality, tourism pressure and carrying capacity, biodiversity, environmental conservation, tourism infrastructure, accessibility, economic effects, and community involvement. Expert evaluations, supported by available evidence, were transformed into triangular fuzzy numbers in order to account for uncertainty and subjectivity in the assessment process. The Fuzzy TOPSIS model was used to calculate the relative closeness of each lake to the ideal solution for sustainable tourism valorization. The results reveal significant differences among the analyzed lakes. Lake Đerdap achieved the highest ranking (Ci = 0.818), followed by Lake Zaovine (Ci = 0.723), Lake Perućac (Ci = 0.644), and Lake Vlasina (Ci = 0.640), reflecting their favorable overall performance across the selected environmental, infrastructural, accessibility, and tourism-related criteria. Lower-ranked lakes were characterized by infrastructural limitations and less favorable performance in selected tourism-related criteria. The study illustrates the applicability of the Fuzzy TOPSIS approach for sustainable tourism evaluation and provides a practical framework for tourism planning, destination management, and policy-making aimed at supporting sustainable lake tourism development in Serbia.

Limnological Review doi: 10.3390/limnolrev26030039

Authors: Adriano Caliman André Luiz dos Santos Fonseca João José Fonseca Leal Rafael Dettogni Guariento Luciana Silva Carneiro Francisco de Assis Esteves

Biodiversity loss in aquatic ecosystems is accelerating, yet whether the effects of different biodiversity facets on biogeochemical processes are consistent or environmentally contingent remains poorly understood. Benthic invertebrate bioturbators drive nutrient exchange at the sediment–water interface of shallow aquatic ecosystems, but how sediment trophic status modulates the effects of their richness, identity, and composition on benthic–pelagic nutrient cycling is unclear. We conducted a factorial microcosm experiment using three functionally and phylogenetically distinct species—Campsurus melanocephalus (Ephemeroptera), Heteromastus similis (Polychaeta), and Heleobia australis (Gastropoda)—assembled as monocultures, bicultures, and tricultures across a gradient of sediment organic matter concentration ([OM]) representative of natural variability in a neotropical coastal lagoon. Species richness produced a consistent, saturating enhancement of NH3 fluxes that was independent of sediment trophic status, while species identity strongly differentiated monoculture effects in a pattern that was likewise stable across the [OM] gradient. In contrast, although biculture compositions did not differ from one another across the [OM] gradient, the overall magnitude of biculture-mediated NH3 fluxes increased with sediment trophic status, suggesting that multispecies assemblage effects are more responsive to environmental context than those of single species. These findings reveal that biodiversity facets diverge not only in how strongly they affect ecosystem functioning, but also in how sensitive their effects are to environmental variation. We therefore conclude that predicting benthic–pelagic nutrient exchange in shallow coastal ecosystems requires considering both the biological structure of bioturbator assemblages and the organic matter context of the sediment.

Limnological Review doi: 10.3390/limnolrev26030038

Authors: Angel Canales-Gutiérrez Gelvi Canales-Manchuria Jesús Miranda-Mamani Alfredo Calatayud-Mendoza Francely Mullisaca-Torres

Schoenoplectus californicus (C.A.Mey.) Soják is a dominant freshwater wetland macrophyte with ecological, technological, and biocultural importance. This multidisciplinary review synthesizes its ecological functioning and environmental applications through a systematized analysis of 66 studies screened by title, abstract, and full text. The literature was classified into seven thematic categories: water treatment and phytoremediation; wetland ecology, biomass, and ecosystem functioning; functional ecology, growth, and landscape connectivity; morphology, anatomy, and functional adaptation; biocultural dimensions, sustainable construction, and technological applications; nutritional and ethnobotanical uses; and cultural heritage and traditional management. Research was concentrated mainly in water treatment and phytoremediation (19 studies, 28.8%), followed by wetland ecology, biomass, and ecosystem functioning (13 studies, 19.7%) and biocultural dimensions, sustainable construction, and technological applications (13 studies, 19.7%). Functional ecology, growth, and landscape connectivity represented 5 studies (7.6%), morphology, anatomy, and functional adaptation represented 4 studies (6.1%), while nutritional and ethnobotanical uses and cultural heritage and traditional management each represented 6 studies (9.1%). Overall, the evidence shows that S. californicus is a multifunctional wetland species whose value emerges from the interaction among ecological functioning, contaminant retention, biomass production, structural adaptation, technological innovation, traditional knowledge, and biocultural continuity.

Limnological Review doi: 10.3390/limnolrev26030037

Authors: Ivo Gavião Prado Marcela Alves de Souza Flávia Freitas Coelho Paulo Santos Pompeu

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Limnological Review doi: 10.3390/limnolrev26030036

Authors: Kacper Nowakowski Łukasz Sługocki

Hypoxia and salinization increasingly co-occur in freshwater and estuarine ecosystems, yet their combined effects under fluctuating oxygen regimes remain poorly resolved. We experimentally quantified survival responses of four planktonic crustaceans (Daphnia magna, Daphnia longispina, Eurytemora velox, and Thermocyclops crassus) along a salinity gradient expressed as conductivity (0.6–7.7 mS cm−1) under two oxygen regimes: sustained hypoxia and repeated short-term hypoxia over 120 h, under standardized food-deprived conditions to isolate abiotic stress effects. Under sustained hypoxia, survival declined monotonically with decreasing oxygen in all species, with marked interspecific differences at ≤2 mg L−1. Under fluctuating oxygen conditions, survival peaked at low to intermediate salinity and declined sharply at elevated salinity, indicating a strong combined effect of oxygen limitation and salinity-related stress. Multivariate analysis identified a significant salinity × oxygen interaction, indicating that the effect of oxygen depletion on survival depended on salinity. Daphnia magna showed the highest tolerance, whereas D. longispina and E. velox were highly sensitive to elevated salinity; T. crassus showed intermediate tolerance. These results indicate that elevated salinity is associated with negative effects under both sustained and episodic hypoxia and that fluctuating oxygen regimes elicit strong combined stress responses. Our findings highlight the importance of combined abiotic stress effects when predicting zooplankton responses in oxygen-depleted and salinizing aquatic ecosystems.

Limnological Review doi: 10.3390/limnolrev26030035

Authors: Florjana Zogaj Tatjana Blazhevska Fatbardh Sallaku Rakesh Ranjan Thakur Hazir Çadraku Upaka Rathnayake Debabrata Nandi Vesna Knights Gorica Pavlovska Pajtim Bytyçi Osman Fetoshi Erinda Lika Valentina Velkovski Bojan Đurin

Groundwater is vital to subsurface ecosystems and to maintaining water supplies for human and environmental needs. Heavy metal pollution of water bodies poses a significant threat to environmental health and human well-being. In this paper, a detailed spatiotemporal analysis of heavy metal pollution at a network of 35 sampling sites is presented for the summer, autumn, and winter seasons. The water samples were analyzed based on the concentration (μg/L) of eight priority metals, such as Lead (Pb), Mercury (Hg), Cadmium (Cd), Arsenic (As), Chromium VI (Cr-VI), Copper (Cu), Zinc (Zn), as well as Iron (Fe). Measuring contamination levels, identifying space hotspots, and explaining seasonal variations were the key tasks. The results show that Fe, Zn, and Cu concentrations are consistently high across seasons, with mean values ranging from 234.3 to 253.2 µg/L (Fe), 163.2 to 175.6 µg/L (Zn), and 107.0 to 109.2 µg/L (Cu), indicating a widespread geogenic or diffuse source. The most significant seasonal deviation was observed in the fall when there were unusually high levels of Cd and Hg, with mean concentrations reaching 0.476 µg/L and 0.312 µg/L, respectively, suggesting a strong seasonal contamination event or mobilization process. The spatial analysis showed that the locations (e.g., L6, L8, L10, L28, L29) exhibited common hotspots for different metals, with maximum concentrations reaching up to 793.3 µg/L (Fe), 602.3 µg/L (Zn), and 508 µg/L (Cu). Principal Component Analysis (PCA) effectively separated seasonal trends and classified metals into anthropogenic (Pb, Cd, Hg, Cr (VI)) and geogenic/diffuse (Fe, Zn, Cu) groups. The health risk assessment indicated no significant non-carcinogenic risk, although children are more vulnerable, while arsenic levels in winter approached the upper acceptable carcinogenic limit (up to 1.1 × 10−4). Overall, the study highlights the importance of multi-seasonal monitoring by capturing temporally abrupt contamination events and provides a novel integrated framework that combines seasonal analysis, spatial hotspot identification, and multivariate techniques, distinguishing it from conventional single-season or non-integrated studies.

Limnological Review doi: 10.3390/limnolrev26030034

Authors: Alessandro Del’Duca Layla Mayer Fonseca Amanda Lemos de Melo Raiza dos Santos Azevedo Hanna Turetti Cardinot Fábio Roland Dionéia Evangelista Cesar

Bacterial density, cell morphology, and carbon stock (C stock) were quantified in seven Brazilian reservoirs (Serra da Mesa, Manso, Itumbiara, Corumbá, Furnas, Mascarenhas de Moraes, and Luis Carlos Barreto) to evaluate spatial and seasonal patterns in these tropical freshwater systems. Subsurface water samples were collected before, during, and after the rainy season. Bacterial density, cell volume, elongation, and biomass were determined using epifluorescence microscopy, and bacterial C stock was estimated from biomass integrated over the 0.5 m sampling depth. C stock varied among reservoirs and sampling periods, with the highest values consistently observed in the largest reservoir (Serra da Mesa, 1.9·10−5 g C). Although bacterial densities showed limited temporal variation, biomass peaked before the rainy season. Density and biomass were negatively correlated with water transparency and positively correlated with turbidity, suggesting that particle-associated organic and inorganic matter influences bacterial biomass accumulation. These findings highlight how environmental conditions shape bacterial biomass and carbon storage in tropical reservoirs, contributing to a broader understanding of microbial carbon pools in these ecosystems.

Limnological Review doi: 10.3390/limnolrev26030033

Authors: Oumaima Zerdeb Allal Labriki Yasmina Bouchatta Karima Labriki Mohamed Sadiki Raja Moussaoui Soukaina El Idrissi Amal Saidi Saïd Chakiri

In arid and semi-arid regions, groundwater recharge is a key process controlling the sustainability of subsurface water resources. This study aims to assess and map the groundwater recharge potential of the Oued Cherrat watershed (Morocco) using an integrated approach combining Geographic Information Systems (GIS) and the Analytic Hierarchy Process (AHP). Six controlling factors were considered: lithology, lineament density, drainage network density, slope, land use/land cover derived from the Normalized Difference Vegetation Index (NDVI), and rainfall. The relative weights of these factors were determined through pairwise comparisons using the Saaty fundamental scale, and the consistency of the judgments was verified (CR < 0.1). The reclassified thematic layers were integrated into a GIS-based weighted overlay model to generate the groundwater recharge potential map. Five recharge classes were identified, ranging from very low to very high. The results show that areas with moderate recharge potential are the most widespread (approximately 37% of the watershed), while high and very high potential zones account for about 25% of the total area. These zones are mainly associated with permeable lithologies, high densities of structural discontinuities, gentle slopes, and low drainage density. In contrast, low to very low recharge potential areas are related to low-permeability formations, steep slopes, and dense drainage networks. The resulting recharge potential map provides a useful decision-support tool for sustainable groundwater management and for identifying priority areas for aquifer protection and artificial recharge planning in the Oued Cherrat watershed.

Limnological Review doi: 10.3390/limnolrev26030032

Authors: Tiago A. Figueiredo Bernardo T. A. Souza Daniel H. C. Salim Caio C. S. Mello Gabriel Pereira Camila C. Amorim

Urban freshwater ecosystems affected by eutrophication and recurrent algal blooms require monitoring approaches capable of representing optical complexity and spatial heterogeneity. This study evaluated an integrated workflow combining proximal in situ hyperspectral sensing, radiometric calibration, spectral filtering, predictor-band selection, data transformation, and machine-learning regression to estimate chlorophyll-a (chl-a) in a tropical eutrophic urban reservoir. Monthly field campaigns were conducted from September 2022 to February 2023, with simultaneous chl-a measurements and hyperspectral image acquisition. After preprocessing, noise removal, and exclusion of anomalous spectra, 82 matched hyperspectral–chl-a observations were retained for model development. Predictor bands were selected using Pearson correlation and F-test analysis, identifying five relevant wavelengths: 530, 535, 682, 687, and 732 nm. Multiple Linear Regression, Random Forest Regressor, Support Vector Regressor, and XGBoost Regressor were tested under different data transformations. The Support Vector Regressor with logarithmic transformation achieved the best performance, with R2 = 0.86 and RMSE = 6.89 µg L−1. The selected wavelengths correspond to spectral regions associated with green reflectance, red chl-a absorption, and red-edge/NIR responses in productive waters. The results indicate that proximal hyperspectral sensing combined with machine learning can support chl-a estimation in optically complex urban reservoirs and provide complementary information for eutrophication monitoring and bloom-management strategies.

Limnological Review doi: 10.3390/limnolrev26030031

Authors: Alexander B. Ruchin Natalia V. Borisova Leonid V. Egorov Mikhail N. Esin Evgeniy A. Lobachev Sergei V. Lukiyanov Gennadiy B. Semishin Irina G. Esina Anna M. Nikolaeva

The study of aquatic biota is of particular interest in view of the considerable anthropogenic impact on freshwater ecosystems in recent decades. Information on regional Trichoptera faunas remains fragmented and scattered in many areas. The present paper provides data from a dataset that includes results of Trichoptera studies conducted since 1981 (primarily during 2018–2025) in 15 regions of European Russia. In total, the dataset contains records from 295 localities. The database includes information on 7759 specimens representing 134 species from 15 families. Eleven Trichoptera species are reported for the first time from the Nizhny Novgorod Region, seven species from the Penza Region, five species each from the Vladimir and Ryazan regions, three species each from the Samara Region, the Republic of Mordovia, and the Volgograd Region, and one species each from the Voronezh, Tambov, and Lipetsk regions, as well as the Chuvash Republic. Hydroptila angulata is recorded for the first time in the Middle Volga Region. The most abundant taxa in the collections belong to the families Limnephilidae, Phryganeidae, and Leptoceridae. Eight species are represented in the dataset by more than 300 specimens each. Hand-held sweep nets were used at 109 localities and yielded 109 species and 3308 specimens. The use of light traps at 45 localities resulted in the collection of 90 species represented by 2651 specimens.

Limnological Review doi: 10.3390/limnolrev26030030

Authors: Remigiusz Tritt

Wind forcing is a primary driver of lake circulation, yet in shallow basins it is strongly constrained by morphometry, limited depth, and aquatic vegetation. We quantified the velocity and direction of horizontal wind-driven currents in Lake Wolsztyńskie (western Poland) and assessed their spatial and vertical variability in relation to depth, wind speed, and effective fetch. Monthly field measurements (June 2019–May 2020) at eight sites showed a consistent, monotonic decline in current speed with depth across the lake. Mean circulation speed increased with wind, but the relationship was weak, indicating that local controls and non-linear response dominate over simple wind–current scaling. In macrophyte-covered littoral zones, currents were substantially attenuated relative to unvegetated sites of comparable depth. Directional analysis revealed that surface flow aligns with wind-driven transport in fewer than half of observations, while compensating (return) currents with opposing directions near the bottom are frequent. Clockwise veering of current direction with depth—expected under a classical Ekman spiral—was only intermittent, consistent with truncation of Ekman dynamics in a shallow water column and a prevailing two-layer circulation pattern.

Limnological Review doi: 10.3390/limnolrev26020029

Authors: David E. Bowles

Aquatic and semi-aquatic plant assemblages, water quality, riparian habitat, and landscape conditions were assessed for 140 ponds located in the Ozarks region in Arkansas and Missouri in order to better describe their occurrences and distributional patterns. Local environmental and landscape-level determinants that shape their diversity and influence their respective distributions, particularly in light of urbanization, were also assessed. Ozark ponds are highly variable in terms of physical structure, habitat quality, and plant diversity. Urban ponds were generally of lower quality in terms of environmental attributes compared to those in non-urban areas, but they had similar plant taxa richness as well as numbers of non-native species compared to their non-urban counterparts. Ponds had high plant diversity (N = 204 taxa, x¯ = 9.89, range = 0–33). Taxa richness increased with increasing pond size, and urban ponds had slightly more species on average compared to non-urban ponds (10.38 vs. 9.58, respectively). Spatial beta diversity of plants showed a high dissimilarity among ponds, with turnover being the dominant fraction. Beta diversity also followed a significant distance-decay model. These findings show that urban Ozark ponds serve as important habitats for a broad variety of aquatic plants.

Limnological Review doi: 10.3390/limnolrev26020028

Authors: Noha Imam

Radioisotopic techniques provide powerful tools for reconstructing the history of lake sediments, offering critical insights into past environmental changes and human impacts. These techniques have contributed significantly to our understanding of past environmental change and have implications for current environmental management practices. This review comprehensively examines various radiometric dating techniques used for lake sediments, with a focus on natural, cosmogenic, and artificial radionuclides, including 210Pb, 137Cs, 241Am, 7Be, 3H, and 14C. The review highlights the widespread use of radionuclides in establishing sediment chronologies across different time scales, from short-term processes (days to decades) to long-term environmental reconstructions spanning thousands of years. Moreover, applications in limnological research are explored, including sedimentation rate estimation, reconstruction of pollution history of trace elements, nutrients, microplastics, and organic compounds, and assessment of anthropogenic impacts and catchment changes. The integration of radioisotopic methods with multiproxy paleolimnological approaches is emphasized as a powerful framework for reconstructing past environmental and ecological conditions. Despite their effectiveness, radioisotopic methods are exposed to several sources of uncertainty, including dispersion in atmospheric isotope flux, post-depositional processes, reservoir effects, and model assumptions. These challenges highlight the importance of careful methodological selection, site-specific evaluation, and rigorous uncertainty assessment in radioisotopic studies of lake sediments. Future research should emphasize refining sediment age-model calibration using region-specific sedimentation parameters and standardized validation procedures, and integrating radiometric techniques with geochemical, biological, and paleolimnological proxies to improve the reconstruction of environmental change in lacustrine systems. Such developments would enhance the interpretation of historical pollution records, sediment accumulation patterns, eutrophication history, and ecological variability, thereby providing scientifically robust information to support evidence-based lake management, restoration programs, and long-term conservation strategies.

Limnological Review doi: 10.3390/limnolrev26020027

Authors: Jesús Antonio Quintero Cardozo Juan Diego Lozano Castro Armando Aguilar Efraín Carvajal Carvajal Alejandro Zuluaga Gómez Kelly Cristina Torres Angulo Oscar Orlando Porras Atencia

Tropical wetlands are highly sensitive to climatic and anthropogenic disturbances, and their macrophyte communities provide valuable information about environmental conditions and habitat structure. This study evaluated the relationship between aquatic macrophyte richness, community composition, and habitat vulnerability to climate change in aquatic ecosystems of the San Luis rural district, Barrancabermeja municipality (Santander, Colombia). Macrophyte communities were characterized at 47 monitoring sites distributed across six mesohabitats: floodplain depressions, swamp, wetland, artificial ponds, naturalized ponds, and stream riparian zones. A total of 63 species belonging to 30 families and 51 genera were recorded. Contrary to theoretical expectations, correlation analyses showed no significant relationship between macrophyte species richness and habitat vulnerability indices (Spearman ρ = −0.118, p = 0.428; Pearson r = −0.069, p = 0.646). However, species richness differed significantly among mesohabitats (Kruskal–Wallis, p < 0.05), indicating strong spatial heterogeneity in aquatic plant distribution. In addition, multivariate analyses using Principal Component Analysis (PCA) revealed that macrophyte community composition was strongly structured by local anthropogenic activities, including livestock farming, oil palm cultivation, and wastewater inputs. Floodplain depressions and artificial ponds were dominated by disturbance-tolerant and eutrophication-resistant species such as Urochloa plantaginea and Salvinia minima, reflecting higher levels of environmental pressure. These results demonstrate that macrophyte community composition, rather than species richness alone, is a more reliable indicator of habitat conditions and anthropogenic disturbance in tropical wetland systems. Overall, this study highlights that taxonomic richness is not a robust predictor of climate-related vulnerability in highly disturbed wetlands and emphasizes the importance of considering species composition and environmental context when assessing ecosystem conditions.

Limnological Review doi: 10.3390/limnolrev26020026

Authors: Aleksandar Slavov Ilia Tamburadzhiev Bogdan Goranov

Mineral waters represent unique limnological ecosystems with stable physicochemical conditions and specialised microbial communities adapted to extreme environments. Bulgarian mineral waters remain comparatively underexplored despite their considerable ecological and biotechnological significance. These studies present a systematic narrative review of microbial diversity, ecological functions, and biotechnological potential of microbial communities from Bulgarian mineral springs. A total of 233 scientific sources published between 1990 and 2026 were analysed, of which 33 focused on Bulgarian sites. Data were retrieved from major scientific databases, regional reports and grey literature. Due to strong methodological heterogeneity, a qualitative synthesis was conducted, supported by bibliometric summaries of research focus and environmental context. The available evidence demonstrates that microbial communities in Bulgarian mineral waters include diverse bacteria, archaea, cyanobacteria, and microalgae that adapt to broad thermal and geochemical gradients. These microorganisms actively participate in element cycles, form complex biofilms, and show numerous physiological adaptations to oligotrophic and extreme temperature conditions. Bulgarian systems broadly reflect global microbial patterns but exhibit additional variability linked to contrasting hydrogeological settings. Many taxa produce thermostable enzymes, antimicrobial compounds, and exopolysaccharides with significant biotechnological potential. The review identifies significant research gaps and emphasises the importance of integrated multi-omics approaches for future exploration of Bulgarian mineral water ecosystems.

Limnological Review doi: 10.3390/limnolrev26020025

Authors: Thanasit Promping Tawatchai Tingsanchali

Most previous drought risk assessments have been done on monthly or annual time-scales, which do not directly correspond to crop conditions during wet and dry seasons. To address this limitation, this study introduces a novel framework for seasonal drought risk assessments. The analysis is conducted across multiple temporal periods, including the past (2020s: 2001–2020), near future (2030s: 2021–2040) and far future periods (2050s–2090s: 2041–2100) while considering the combined impacts of land use and climate change scenarios RCP4.5 and RCP8.5. Multi-drought hazard indices were developed to characterize drought conditions and evaluated for dry seasons (November to April) and wet seasons (May to October). Groundwater storage outflow was incorporated into the analysis to reflect its critical role as an alternative water source. Under RCP8.5 in dry seasons, the results show a decrease in drought risks from very high to high from the 2030s to the 2070s followed by an increase toward the 2090s. Meanwhile, in wet seasons under RCP8.5, the results exhibit an increase from very low to low for the 2030s–2090s. Adoption of drought-resistant crop varieties and improvement of irrigation systems in irrigated areas, as well as adaptive irrigation management in non-irrigated areas, were found to reduce drought damage in the future.

Limnological Review doi: 10.3390/limnolrev26020024

Authors: Satyam Shah

Water hyacinth (Eichhornia crassipes) is among the world’s most invasive aquatic macrophytes, yet quantitative models of shoreline preference remain absent for Lake Victoria. This study developed a distance-based quantitative framework for spatial distribution and decay modelling to quantify seasonal nearshore accumulation dynamics in Winam Gulf, Kenya, using Sentinel-2 imagery. A Support Vector Machine classifier with polygon-mean feature extraction achieved 94–96% accuracy, supported by strong spectral separability (Jeffries–Matusita distance > 1.9 in six bands). During peak dry season, water hyacinth covered 405.81 km2 (27.1% of gulf area) and occurred significantly closer to shore than open water (mean preference = 687.9 m; 95% CI: 616.6–753.7 m; p < 0.001). Water hyacinth was 3.10 times more likely than open water to occur within 100 m of shoreline, with 48% of biomass concentrated within 2 km. A power-law decay model of odds ratio with shoreline distance provided superior fit (R2 = 0.870, F = 10.06, p = 0.047) compared to exponential decay (R2 = 0.477, p = 0.378). Critically, pronounced nearshore preference occurred only during dry-season conditions (+687.9 m to +1946.6 m), while wet–dry transition periods showed no significant preference (−124.2 m; p = 1.00), supporting wind-driven Stokes drift as the dominant transport mechanism and enabling seasonal prioritization of nearshore management interventions.

Limnological Review doi: 10.3390/limnolrev26020023

Authors: Ann Maria Najjuma Gbeminiyi John Oyewole

Although South Africa has an extensive water infrastructure, it continues to face significant water scarcity due to its semi-arid climate, increasing urbanisation, ageing infrastructure, and pollution. These challenges, coupled with climate change and increasing water demand, have led to inefficiencies across the water value chain, particularly in rural areas. This review paper evaluates the current adoption of predictive analytics in South Africa’s water management system through a systematic literature review. It identifies the current applications, implementation gaps, and key system components that are suitable candidates to enhance efficiency, resource planning, and long-term sustainability in the sector. The findings show that while predictive models are being applied in urban systems for demand forecasting and proactive maintenance, only 15% of the reviewed studies address their actual adoption in rural or under-resourced contexts. This underscores the need for more inclusive development strategies to ensure equitable water service delivery. Although strides have been made in research and innovation, a major barrier is the slow transition from research to operational deployment, which hinders the full realisation of these technologies’ benefits that are essential for water supply sustainability and availability.

Limnological Review doi: 10.3390/limnolrev26020022

Authors: Fatima Daide Eleni Ioanna Koutsovili Mohammed Mouad Mliyeh Abderrahim Lahrach Isavela N. Monioudi Ourania Tzoraki

Freshwater lakes in Mediterranean regions are highly sensitive to climatic variability, particularly to droughts intensified by rising temperatures and increasing atmospheric evaporative demand. This study investigates drought variability and ecosystem responses in the Trichonida basin, the largest natural freshwater system in Greece, using an integrated approach that combines the Standardized Precipitation Evapotranspiration Index (SPEI) at multiple time scales with satellite-derived Normalized Difference Vegetation Index (NDVI), Crop Water Stress Index (CWSI), and lake surface water temperature. SPEI analysis revealed increasingly recurrent and persistent drought conditions in recent years, especially at medium- and long-term scales. NDVI exhibited pronounced seasonal variability and a moderate long-term increase at the basin scale, largely associated with agricultural activity and irrigation practices, while sharp declines were observed during severe drought episodes. CWSI showed strong seasonal patterns characterized by recurrent summer water stress events, but no significant long-term trend. Correlation analysis indicated positive relationships between NDVI and SPEI at medium- to long-term time scales, and significant negative correlations between CWSI and SPEI at short and medium time scales. A strong relationship between NDVI and CWSI further suggests the sensitivity of vegetation greenness to water stress, particularly during summer and autumn. Lake surface water temperature exhibited seasonal warming trends that coincided with periods of increased vegetation water stress. Drought-related water risks arise for calcareous fens dominated by Cladium mariscus in the Lake Trichonida system, a habitat of high conservation value, whose productivity is strongly seasonally controlled and closely linked to thermal dynamics. Overall, the combined multi-indicator analysis provides valuable insights into drought impacts and seasonal ecosystem vulnerability in Mediterranean lake basin environments, highlighting the importance of integrated monitoring frameworks for sustainable freshwater ecosystem management under increasing climatic variability.

Limnological Review doi: 10.3390/limnolrev26020020

Authors: Rubén Hernández-Morales Isabel Israde Alcantara Nicolás Waldmann Gabriela Zanor

This article analyzes the information provided by the sedimentary sequences of 29 lakes in central Mexico, 10 of which are currently paleolakes. During the Late Quaternary, the lakes of central Mexico experienced environmental changes driven by global and local climatic and geological processes, showing regional trends of wet and dry periods. Paleoenvironmental reconstructions are based on the use of 20 indicators, including diatoms, pollen, geochemistry, mineralogy, granulometry, magnetic susceptibility, and isotopes. Seven major episodes are recognized in the historical evolution of the lakes of central Mexico: i. Late Miocene–Pliocene: A period that includes the formation of large lakes in central Mexico by volcano tectonic activity under a regime of continuous humidity. ii. Pleistocene–Drought and climatic variability of the interglacial period. iii. Drying and successive lacustrine transgression during the Last Glacial Maximum. iv. Spatial climate variability in the Heinrich 1 period. v. Lake regression and expansion of terrestrial vegetation in the Bølling–Allerød period. vi. Transgression of lakes of central Mexico during the Younger Dryas and mid-Holocene periods. vii. Late Holocene: A period that includes lake desiccation influenced by the impact of human activities. The analysis of the data allows us to propose six challenges for the scientific community in future research of central Mexico.

Limnological Review doi: 10.3390/limnolrev26020021

Authors: Isabela da Silva Pedro Rochinha Tamara Daiane de Souza Múcio André dos Santos Alves Mendes Aníbal da Fonseca Santiago

Mining activities can generate effluent contamination with potentially toxic elements such as iron (Fe) and manganese (Mn), posing environmental and technological challenges, particularly during mine closure and the decommissioning of mining structures. Constructed wetlands have been proposed as a nature-based, passive, and low-cost alternative for treating mining effluents; however, the mechanisms, controlling factors, and performance patterns governing Fe and Mn removal remain insufficiently synthesized across different wetland configurations and effluent types. This study performs a systematic review combined with a meta-analysis to synthesize Fe and Mn removal mechanisms, quantify removal performance, and identify the operational, hydraulic, physicochemical, and biological factors influencing system performance. A total of 55 primary studies were analyzed, comprising 155 observations for Fe and 96 for Mn. The results indicate that Fe removal is generally high (median ln(RR)ln(RR) = −1.89), whereas Mn removal is more variable and less efficient (median ln(RR)ln(RR) = −0.59), highlighting the greater complexity of Mn removal processes. Fe removal was mainly associated with hydraulic retention time and pH, while Mn removal was more strongly influenced by redox conditions and the type of support material, particularly mineral substrates. Overall, wetland performance is governed by the interaction among hydraulic retention time, pH buffering, redox conditions, support media reactivity, vegetation-mediated rhizosphere processes, and influent geochemistry. A significant research gap remains regarding neutral mine drainage (NMD), since this effluent category was not explicitly reported in the primary studies and could not be robustly isolated as an independent subgroup, especially in relation to Mn removal efficiency.

Limnological Review doi: 10.3390/limnolrev26020019

Authors: Virgilio Zúñiga-Grajeda Jennifer Aleysha Lomeli Freddy Hernán Villota-González César Alejandro García-García Belkis Sulbarán-Rangel

Freshwater ecosystems are increasingly affected by eutrophication, sediment loading, and other anthropogenic pressures, creating a growing need for monitoring frameworks that are spatially extensive, temporally consistent, and methodologically robust. Although in situ sampling remains essential, its limited spatial coverage and operational constraints have accelerated the use of satellite remote sensing combined with artificial intelligence (AI) and machine learning (ML) for water quality assessment. This review critically examines recent studies published between 2020 and March 2026 on the estimation of physicochemical water quality parameters in lakes and rivers using remote sensing, with particular attention to the methodological structure of image processing workflows rather than performance metrics alone. The synthesis shows that predictive performance is strongly conditioned by three interrelated stages: atmospheric correction (AC), spectral feature construction, and validation design. Across the reviewed studies, substantial variation is observed in atmospheric correction processors, spectral engineering strategies, and model architectures, leading to differences in the spectral inputs and analytical conditions used for model development. Validation approaches remain highly heterogeneous and often rely on internal data splits without geographically independent testing, which weakens claims of model generalizability. In addition, few studies explicitly distinguish algorithmic, matchup, and preprocessing uncertainties, revealing a persistent gap in uncertainty reporting. Overall, the review suggests that improvements attributed to newer ML models may partly reflect upstream preprocessing choices rather than algorithmic superiority alone. Future research should prioritize transparent reporting of atmospheric correction pipelines, structured uncertainty decomposition, standardized validation protocols, and cross-site transferability assessments. By synthesizing these methodological patterns, this review provides a consolidated methodological synthesis that supports improved reproducibility, comparability, and operational reliability of remote-sensing-based freshwater quality monitoring.

Limnological Review doi: 10.3390/limnolrev26020018

Authors: Turnwait Otu Michael

Riverine systems in tropical deltaic environments are increasingly exposed to hydrological variability driven by climate change, sea level rise, and extreme precipitation. In Nigeria’s Niger Delta, recurrent flooding and environmental degradation are intensifying pressures on freshwater ecosystems and dependent communities. This study examines hydrological stressors in riverine settlements of Bayelsa State and explores associated socio-ecological responses. Using an exploratory qualitative design, data were collected from 51 women residing in highly vulnerable riverine communities through 24 in-depth interviews and three focus group discussions. Thematic analysis identified prolonged flooding, riverbank erosion, salinity intrusion, water quality deterioration, and oil pollution, as key drivers of declining fisheries, reduced agricultural productivity, and household water insecurity. These stressors have prompted relocation, livelihood diversification, and reliance on indigenous adaptation practices. The study recommends: (1) installation of community-based flood early warning systems; (2) routine monitoring of surface water quality and salinity; (3) enforcement of oil spill remediation and pollution control measures; (4) rehabilitation of wetlands and natural drainage channels; and (5) targeted support for climate-resilient livelihoods such as aquaculture and elevated farming systems. These measures are critical for sustaining freshwater ecosystems and strengthening resilience in vulnerable deltaic communities.

Limnological Review doi: 10.3390/limnolrev26020017

Authors: Anja Batina

Freshwater ecosystems are increasingly threatened by eutrophication and other anthropogenic and climate-driven pressures that undermine ecological functioning and biodiversity. This study evaluates the transferability of a GIS-based multi-criteria decision analysis (GIS–MCDA) framework with Fuzzy Analytic Hierarchy Process (F-AHP), originally developed for a shallow coastal lake, to a morphologically distinct deep upland lake (Lough Tay, Ireland). Monthly in situ measurements at a single monitoring point in 2024 were analysed together with meteorological variables using Spearman rank correlations. Because spatial interpolation of in-lake water quality parameters was not feasible, eutrophication susceptibility was mapped using four external spatial drivers: distance from water resources (River Cloghoge inflows), land-based nitrogen export potential, distance from environmental pollutants represented by the transportation network, and a wind exposure index derived from a DEM and wind-rose analysis. Criteria were standardized with fuzzy membership functions, weighted using F-AHP (consistency index 0.056), and aggregated using weighted linear combination at 25 m resolution. The resulting Eutrophication Susceptibility Index (ESI) ranged from 0.18 to 0.81, indicating generally moderate to good conditions, with higher ESI values concentrated in the northern lake sector near inflow zones. The results demonstrate that GIS–MCDA can be adapted to lakes with limited monitoring by relying on external drivers, providing a spatial proxy for susceptibility rather than measured trophic status.

Limnological Review doi: 10.3390/limnolrev26020016

Authors: Florjana Zogaj Tatjana Blazhevska Fatbardh Sallaku Rakesh Ranjan Thakur Hazir Çadraku Upaka Rathnayake Debabrata Nandi Vesna Knights Gorica Pavlovska Pajtim Bytyçi Erinda Lika Osman Fetoshi Valentina Velkovski Rozeta Hasalliu Bojan Đurin

Physicochemical and microbiological parameters are important indicators of drinking water quality. This study assessed the quality of groundwater used for drinking in four regions of Kosovo at 16 locations using an integrated assessment framework that combined physicochemical, microbiological, and Water Quality Index (WQI) approaches. The results reveal substantial spatial variability in water quality. While most physicochemical parameters remained within recommended limits, elevated values of total dissolved solids (up to 2792.5 mg/L), electrical conductivity (up to 2768.5 µS/cm), nitrate (up to 60.75 mg/L), and phosphate (up to 0.875 mg/L) were observed at several locations, indicating localized hydrogeochemical and anthropogenic influences. Dissolved oxygen levels were generally low (0.68–5.49 mg/L), reflecting limited aeration conditions in groundwater systems. Microbiological analysis revealed critical contamination, with Escherichia coli concentrations up to 299.9 CFU/100 mL, and all sampling sites exceeded permissible limits, indicating widespread fecal pollution and rendering the groundwater unsafe for direct consumption. WQI assessment further confirmed this condition, where 93.75% of locations were classified as medium quality using the NSF-WQI method, whereas the WA-WQI method categorized 68.75% of samples as poor and 6.25% as very poor. The novelty of this study lies in the integrated evaluation of hydrogeochemical processes and microbiological contamination using dual WQI methods and multivariate statistical analysis, providing a comprehensive understanding of groundwater degradation pathways. The findings are significant for policymakers, environmental managers, and public health authorities, highlighting the urgent need for groundwater treatment, improved sanitation infrastructure, and sustainable water resource management strategies in vulnerable regions.

Limnological Review doi: 10.3390/limnolrev26020015

Authors: Ivan Kovalchuk Vitalii Martyniuk Vasyl Korbutiak Ivan Zubkovych Tetiana Pavlovska Valentyna Stelmakh Yaroslav Kurepa

The Somyne lake-mire system is a unique wetland landscape complex in the Polissia region of Ukraine and forms part of the Rivne Nature Reserve. Its ecological importance is internationally recognised through its designation as the Ramsar wetland “Somyne Peatland Massif”. Effective conservation of this wetland requires an understanding of the factors controlling the functioning of the lake and its drainage basin, considered in this study as a lake-basin system (LBS). The aim of this study is to assess the geoecological condition of the Somyne LBS using the principles of landscape limnology and the basin approach. The research integrates morphological, morphometric, hydrological, landscape-metric, hydrochemical and geochemical analyses. These are complemented by bathymetric modelling, landscape mapping, and analysis of long-term meteorological observations. The results identify key natural and anthropogenic drivers shaping the functioning of the system, characterise the hydrochemical state of lake waters and the geochemical properties of bottom sediments, and describe the spatial distribution of bottom sediments and the bathymetric structure of the lake basin. A multivariate algorithm for the geoecological assessment of lake-basin systems is proposed, providing a framework for comparative analysis of small lakes in the Polissian lake region under climate change and increasing anthropogenic pressure.

Limnological Review doi: 10.3390/limnolrev26020014

Authors: Jose Alberto Calizaya-Anco Yvonne Magalí Cutipa-Díaz David Gonzalo Rubira-Otarola Katia Aracely Denegri-Limache Elmer Marcial Limache-Sandoval

High Andean lagoons in southern Peru have critical hydrological and ecological functions; however, long-term time series integrating trophic, integral quality, and metal contamination metrics to support adaptive management are lacking. A total of 1846 records (2015–2024) from four systems (3100–4600 m a.s.l.) were analyzed using seven indices assessing trophic status (TSItsr, TRIX), general water quality (OWQI, WQIHA, CCME-WQI), and metal contamination (HPI, CD). Temporal trends were assessed using Mann–Kendall and Theil–Sen slope; spatial heterogeneity using Kruskal–Wallis and Dunn–Bonferroni comparisons; controlling factors using distance-based redundancy analysis (999 permutations); and functional typology using Ward’s hierarchical clustering on Z-standardized data. 93% of the series lacked monotonic trends (52/56 lagoon–stratum × index combinations), demonstrating high interannual stability; spatial variance was marked (ε2 = 0.73 in CCME-WQI). Distance-based redundancy analysis (db-RDA) explained 24.6% of total variability, with lake identity as the dominant driver (~45%), followed by temporal change (~8%). Four functional archetypes emerged, including a metal-eutrophic hotspot (HPI ≈ 213; CD ≈ 19) and recovering reservoirs with intermediate water quality indicators. Joint thresholds (TSItsr ≥ 60 + HPI ≥ 100) establish early-warning criteria, with Paucarani (HPI = 213) approaching the critical domain where metal-driven stress may facilitate cyanobacterial dominance. Systems show temporal resilience but strong spatial divergence induced by local pressures. The proposed typology and thresholds provide an operational basis for early warnings and prioritization of remediation actions in high-mountain ecosystems subject to increasing anthropogenic stress.

Limnological Review doi: 10.3390/limnolrev26020013

Authors: Florencia Soledad Alvarez Dalinger Lucia Verónica Laureano Liliana Beatriz Moraña Claudia Nidia Borja María Laura Sanchéz Verónica Laura Lozano

Raphidiopsis raciborskii is one of the most widely reported cyanobacteria worldwide, responsible for dense blooms and cyanotoxin production. Classified as invasive, it has been documented across all continents except Antarctica. While its distribution has been extensively studied, abiotic factors have consistently emerged as the main determinants of its success, which are therefore the focus of the present study. The objective of the present review is to synthesize findings from both experimental and field-based studies to identify which are the key drivers of its dominance. In total, 30 abiotic factors were reported, reflecting the broad strategies of the species. Results show the temperature as a consistent universal factor (11–35 °C), while differences were found regarding nutrient dynamics. Particularly, nitrogen forms and N/P ratios predominated in field-based evidence, whereas photosynthetically active radiation was disproportionately emphasized within experimental studies under controlled conditions. Factors such as salinity and micronutrients, and synergistic interactions remain critically understudied, limiting predictive capacity under global change scenarios. Understanding which combinations of these drivers create favorable conditions is essential for anticipating bloom dynamics in order to establish management strategies for avoiding or mitigating the negative impact of them.

Limnological Review doi: 10.3390/limnolrev26020012

Authors: Steven Jacobs Dimitri Van Pelt Ignacy Kardel Martijn Van Roie Jonas Schoelynck

In 2013, plants tentatively identified as Potamogeton nodosus Poir. were discovered in the Biebrza River (NE Poland). In this study, the authors confirm the presence of P. nodosus by collecting new specimens at the original location and analyzing their microscopic characteristics, an essential step due to significant overlap in macromorphological traits with the closely related P. × fluitans complex. Additionally, new occurrences of the species within Biebrza National Park are reported, and the possibility that its spread is linked to rising river water temperatures is discussed. The authors provide evidence of an increasing average water temperature in the Biebrza River and of a northbound expansion of P. nodosus in Europe. Given similar trends observed elsewhere in Northern Europe, it is likely that P. nodosus will continue to expand its range northward in response to ongoing climate change.

Limnological Review doi: 10.3390/limnolrev26010011

Authors: Wallas Benevides Barbosa de Sousa Maria Fernanda Barros Gouveia Diniz Fabio Hideki Yamada

Anostomidae is one of the most diverse families within the order Characiformes and is widely distributed across the river basins of the Neotropical region. Anostomids are known to host a rich diversity of metazoan parasites, including ectoparasites, such as monopisthocotylans, and endoparasites, such as nematodes, cestodes, and digeneans. The present study aims to develop an inventory of metazoan parasites recorded in fish of the Anostomidae family. A bibliographic review of metazoan parasite species in anostomids was conducted, using searches in different databases. This bibliographic review was complemented with information from books and book chapters on ictioparasitology. The data were compiled until January 2025. Based on the review, 191 taxa (126 are described at the species level and 65 were identified only to the genus level or higher taxonomic categories) of metazoan parasites associated with anostomid fishes were found. Monopisthocotyla and Nematoda were the taxonomic groups with the most parasitic associations at the species level, with 31 and 30 species, respectively. This study presents a comprehensive and updated inventory of metazoan parasites associated with fish from the family Anostomidae, covering over 170 years of research (1850–2025). This survey highlights the importance of anostomids as hosts for a rich parasitic fauna.

Limnological Review doi: 10.3390/limnolrev26010010

Authors: Manu Priya Shvetambri Jasrotia Akebe Luther King Abia

Freshwater ecosystems play an important role in human survival, ecosystem functioning, and biodiversity conservation, yet industrialisation and urbanisation dump over 80% of untreated sewage into them. This inadequate wastewater management leads to enteric pathogens like Escherichia coli, Salmonella, Shigella, Campylobacter, Vibrio cholerae, Pseudomonas aeruginosa, and Legionella pneumophila that are responsible for a wide range of waterborne human diseases globally with extensive morbidity and mortality. The World Health Organization (WHO) estimates that at least 2 billion individuals drink water contaminated with pathogens, resulting in illnesses like cholera, dysentery, and diarrhoea, and approximately 50,000 diarrheal deaths annually. Classical epidemiology approaches are the basis for determining disease burden in public health, but they are limited in their capacity to predict future health risks. Quantitative microbial risk assessment (QMRA) addresses this by estimating the potential health risks of any exposure to microbial pathogens in any environment using four key elements, which include the identification of the microbial hazards, human exposure to the hazard through diverse activities, dose–response relationships, and the estimated risk of the infection. This review summarises information on freshwater pathogens, their occurrence, sources and health implications. The methodological approaches of QMRA in freshwater systems are reviewed with examples drawn from recreational activities, drinking water, and wastewater-impacted environments. Global QMRA studies indicate a wide range of infection risk estimates, reflecting differences in water sources, pathogens, and exposure conditions. Thus, QMRA is known to be a valuable public health tool for freshwater ecosystems, linking microbial contamination dynamics to health risk estimates that support proactive management and policy-relevant decision-making.

Limnological Review doi: 10.3390/limnolrev26010009

Authors: Camila Nader Maria Cecília Miotto Carlos Yure B. Oliveira Leonardo R. Rörig

Raphidiopsis raciborskii (formerly Cylindrospermopsis raciborskii) is a bloom-forming cyanobacterium that employs the production of toxins and other secondary metabolites as a competitive and allelopathic strategy. This study evaluated the effects of exudates from R. raciborskii cultivated under three nitrogen-to-phosphorus (N:P) ratios on the photosynthetic performance of Limnothrix sp. (cyanobacterium), Chlorella sp. (green algae), and Raphidocelis subcapitata (green algae), using pulse-amplitude-modulated (PAM) fluorometry. Rapid light curves (rETR) obtained under different N:P ratios and across the three target species exhibited similar response patterns. Likewise, effective quantum yield (ΦPSII), regulated (Y(NPQ)) and non-regulated (Y(NO)) energy dissipation showed comparable profiles among treatments after 24 h of exposure. Overall, the results of the present study indicate that, within the 24 h exposure period and based on the fluorescence parameters measured, exudates produced by R. raciborskii under the tested nutrient conditions did not cause measurable alterations in the photosynthetic performance of the three evaluated species.

Limnological Review doi: 10.3390/limnolrev26010008

Authors: Gabriel dos Anjos Guimarães Gysele Maria Morais Costa Isreele Jussara de Azevedo Rodrigues Manoel Henrique de Souza Neto Gustavo Frigi Perotti Bruno Sampaio Sant’Anna Gustavo Yomar Hattori

Pollution from solid waste results mainly from improper disposal and inadequate waste management, causing environmental degradation and risks to human health. This study characterized solid waste pollution along the left bank of the Amazon River within the urban segment of Itacoatiara, Brazil. Eleven sampling points were established across upstream, midstream and downstream sections. Solid waste was present at densities ranging from 0 to 0.65 items·m−2, with a mean density of 0.15 ± 0.14 items·m−2. Higher concentrations were observed in the midstream sections of the left bank (0.21 ± 0.16 items·m−2), and statistical analyses showed significant differences among sections. Plastics predominated among all materials (0.50 ± 0.60 items·m−2), and statistical analyses showed significant differences among the types of solid waste, with fragments mainly originating from bags, bottles, and fibers. Plastics were recorded in most sampling sections, with particularly high abundance in the midstream sections of the river (0.98 ± 0.80 items·m−2) and statistical analyses showed significant differences among sections and across material types. According to the general index and the clean coast index, sampling areas ranged from “clean” to “extremely dirty”, with midstream sections most impacted. The plastic abundance index indicated high plastic contamination, and hazardous waste was more frequent in the upstream and midstream sections. The environmental status index classified all sections as both “good” and “bad”, indicating compromised environmental quality and ecological integrity. These results show human pressure on the Amazon River banks and degraded environmental quality, supporting waste management policies, mitigation, monitoring, and environmental education to protect ecosystems and reduce risks to riverside communities.

Limnological Review doi: 10.3390/limnolrev26010007

Authors: Luis Alfredo Hernández-Vásquez Mauricio Rojas-Ascensión Sergio Reyes Rosas Rubén Daniel Hernández Cruz Miguel Ángel Vega-Ortega Gregorio Hernández-Salinas Marco Antonio Benítez-Espíndola Luis Carlos Sandoval Herazo

Urban river degradation demands remediation strategies that are both environmentally sustainable and technically feasible. This study evaluated the performance of Floating Treatment Wetlands (FTWs) vegetated with Chrysopogon zizanioides (vetiver) and incorporating four substrate configurations: leaf litter (LL), red volcanic rock (RVR), corn cobs (CC), and a composite mixture of all three, for the rehabilitation of the “Paseo de Los Ahuehuetes” River in Veracruz, Mexico. Over a 182-day monitoring period, in situ water quality parameters and plant growth responses were systematically assessed. The results indicate that substrate selection is a decisive design factor governing the establishment and development of C. zizanioides in FTWs. Among the substrates tested, LL exhibited the most favorable performance, achieving the highest plant survival (82%), enhanced shoot elongation (71.5 ± 12.1 cm), greater root development (49.7 ± 10.0 cm), and the highest relative growth rate (0.028 g g−1 d−1), with statistically significant differences (p < 0.05) compared to CC. Additionally, localized improvements in water quality within the FTW zone were observed, including an increase in dissolved oxygen (2.07%) and a reduction in total dissolved solids (5.65%), likely associated with intensified rhizospheric processes. Overall, these findings identify leaf litter as a low-cost, locally available, and environmentally sustainable substrate that enhances vetiver establishment in FTWs. The study provides practical, evidence-based criteria for the design of nature-based phytoremediation systems aimed at the restoration of urban river ecosystems.

Limnological Review doi: 10.3390/limnolrev26010006

Authors: Mustafa Tanrıverdi Tülay Erbesler Ayaşlıgil

Floods are natural disasters that cause significant socioeconomic and environmental losses in both urban and rural areas. Within the framework of spatial planning, precautionary measures against flood hazards can be developed using analytical approaches based on different modeling techniques. In this study, flood-prone areas in the Melen Basin, Türkiye, were identified and mapped using five statistical methods, namely Frequency Ratio (FR), Shannon Entropy (SE), Evidential Belief Function (EBF), and the hybrid models EBF–SE and EBF–FR. The analysis was conducted using a flood inventory and environmental datasets covering the period 2019–2024, including elevation, slope, aspect, land use, plan and profile curvature, drainage density, distance to river, curve number, long-term average precipitation, geological formation, soil depth, topographic wetness index, sediment transport, and stream power index. Model performances were evaluated using the Receiver Operating Characteristic (ROC) curve and the Area Under the Curve (AUC). The results indicate that the SE method achieved the highest predictive performance (AUC = 0.979), followed by FR (0.974), EBF–SE (0.972), EBF–FR (0.968), and EBF (0.966). According to the FR and SE models, elevation, lithology, and slope were identified as the most influential factors in flood occurrence. In the evaluation of the success index of the models, the following values were determined according to their size: EBF–SE (96.0), SE (94.4), EBF (91.8), FR (81.9), and EBF–FR (79.4). In the classification of flood sensitivity maps, Natural Breaks (Jenks) is the most successful method according to the success index. The findings demonstrate that data-driven and hybrid models can effectively support flood risk assessment and provide valuable input for land-use planning and flood risk management.

Limnological Review doi: 10.3390/limnolrev26010005

Authors: Włodzimierz Marszelewski Piotr Rzymski Piotr Klimaszyk

The designation of 2026 as the World Economic Forum’s Year of Water underscores the growing recognition of freshwater systems as critical to climate resilience, biodiversity conservation, and socio-economic stability. Coinciding with this global initiative, the Polish Limnological Society (PLS) marks its 25th anniversary, offering an opportunity to reflect on the evolving role of limnology in addressing contemporary environmental challenges. Founded in 2001, PLS has advanced integrative research on inland waters, fostered international scientific cooperation, supported scholarly publishing, and promoted societal engagement with freshwater issues. This Perspective highlights society’s contributions to understanding the natural and anthropogenic transformations of lakes and reservoirs, its commitment to open science and education, and its engagement in climate advocacy to address global water security. We argue that the experience of PLS illustrates how sustained, community-driven limnological science can inform policy, management, and public discourse, reinforcing the imperative to safeguard inland waters in an era of accelerating global change.

Limnological Review doi: 10.3390/limnolrev26010004

Authors: Adriano Teixeira de Oliveira Marcio Quara de Carvalho Santos Jefferson Raphael Gonzaga de Lemos Ariany Rabello da Silva Liebl Maria Fernanda da Silva Gomes Maiko Willas Soares Ribeiro Rayana Melo Paixão Suelen Miranda dos Santos Adriene Nuzia de Almeida Carvalho Cristiane Cunha Guimarães João Paulo Ferreira Rufino Lucas Maia Garcês Caterina Faggio Paulo Henrique Rocha Aride

Determining hematological values is essential to provide baseline health and condition data. We evaluated the hematological parameters of free-living individuals of Caiman crocodilus and Melanosuchus niger from the middle Negro River region of Brazil. We captured 18 C. crocodilus and 16 M. niger. Blood was drawn using syringes containing 10% EDTA, and blood parameters were determined as previously described. The analyzed erythrocyte parameters were similar across the species, demonstrating that, despite their different sizes, they share similar strategies for oxygen absorption and transport in the blood. In the morphological analysis of blood cells, erythrocytes, erythroblasts, thrombocytes, lymphocytes, neutrophils, azurophils, heterophils, and basophils were found, and, in the quantification of leukocytes and thrombocytes, it was noted that lymphocytes are the central cells in the blood of the Amazonian caiman. In the plasma metabolite results, no significant differences were observed between glucose and total protein levels. Key physiological parameters were established to assess the health of C. crocodilus and M. niger, enabling the application of this information to sustainable captive production programs and helping to reduce pressure on wild populations.

Limnological Review doi: 10.3390/limnolrev26010003

Authors: Guilherme Silva Miranda João Gustavo Mendes Rodrigues Thamirys Borges Galdino Marcia Regina da Silva Costa Rafael Costa Leite Thiago Ferreira Soares

Melanoides tuberculata is one of the world’s main invasive snail species; therefore, mapping its occurrence is essential for predicting its dispersion patterns and proposing control measures. This study aimed to map the occurrence of M. tuberculata and its associated parasites in a tourist waterfall complex located in Fortaleza dos Nogueiras, Southern Maranhão, Brazil. We collected snails over three months (July, August, and September 2025) in the Castanhão, Esmeralda, and Recanto das Águias waterfalls, and in the Panela stream, to estimate their reproductive stage and to assess the presence of parasites. We demonstrated for the first time the occurrence of M. tuberculata at all evaluated collection points. Morphological data of the shells suggested that the M. tuberculata populations were in the initial phase of their reproductive cycle; however, some specimens showed a complete reproductive stage. Additionally, we found M. tuberculata infected with trematode larvae that resembled the Gymnocephalus-type cercariae in the Castanhão waterfall and Panela stream. Therefore, we updated the distribution of M. tuberculata in Brazil and discussed the possible environmental and public health impacts of this species in the study area.

Limnological Review doi: 10.3390/limnolrev26010002

Authors: Olumide Temitope Julius Francesco Zangaro Roberto Massaro Marco Rainò Francesca Marcucci Armando Cazzetta Franca Sangiorgio John Bunmi Olasunkanmi Valeria Specchia Oluwafemi Ojo Julius Mahallelah Shauer Alberto Basset Maurizio Pinna

Three ageing reservoirs in Ekiti State, Nigeria (Ureje constructed in 1958, Egbe in 1982, and Ero in 1989), were comparatively assessed to evaluate fish assemblages and their conservation relevance. Despite the absence of formal fisheries governance, all three reservoirs supported temporally stable fish communities with low overall diversity. A core assemblage of six species dominated across sites, while species richness increased from seven species in the small urban Ureje reservoir to nine species in the larger and more rural Ero reservoir. Four native species that have become locally scarce in surrounding river systems (Heterotis niloticus, Parachanna obscura, Hepsetus odoe, and Hyperopisus bebe) persisted at low but consistent abundance. Aquatic environmental variables remained within suitable limits for freshwater fishes, and trophic structure appeared intact across the reservoirs. Catch density was substantially higher in the urban reservoir compared to the rural systems, reflecting spatial differences in fishing intensity. Overall, the findings demonstrate that small tropical reservoirs can function as important freshwater habitats that sustain fish biodiversity and fisheries production in modified landscapes.

Limnological Review doi: 10.3390/limnolrev26010001

Authors: Andrzej Hutorowicz

The ecological status of lakes based on ichthyofauna, as defined by the Water Framework Directive, is assessed using intercalibrated methods. However, the methods adopted (in Poland, the Lake Fish Index LFI-EN method, based on results of one-off fishing with multi-mesh gillnets) are labor-intensive and do not allow for frequent repeat testing. Therefore, the concept of a simple model describing changes in the relative number of single traces in the vertical profile (according to the TS target strength distribution) in a lake is presented, as well as an index (the sum of deviations from such a model), enabling quantification of the similarity of TS distributions in lakes with this model. Preliminary analyses were conducted on acoustic data collected in Lake Dejguny. This lake—the condition of which could be estimated based on historical data using the relationships between LFI and the degree of lake eutrophication (expressed by Carlson’s TSI)—was assessed as having a good status in 2006, whereas in 2021, (based on LFI-EN) it had a moderate status. The study tested the TS distribution model, calculated as the arithmetic mean of the relative number of single traces in 2 m-thick layers. It was also shown that the proposed indicator can effectively signal deterioration of ecological status—the sum of the absolute values of the TS distribution deviations in 2021 (moderate status) from the model was more than seven times greater than the sum of the deviations of the distributions from which the model was built (good status). The obtained results confirmed the hypothesis about the possibility of determining a characteristic distribution of single traces in the vertical profile when the lake was classified as being in good condition.

Limnological Review doi: 10.3390/limnolrev25040055

Authors: Neal D. Mundahl

Urban streams are subjected to a variety of impacts from stormwater runoff, channelization, routing through culverts, and highly modified riparian zones, all of which can have negative effects on stream habitats and resident fish communities. Coldwater trout streams in urban areas may be especially impacted due to their normally low fish diversity and the higher intolerance of those species to such factors as stream temperature, dissolved oxygen concentrations, and water chemistry. Fish communities were examined at two sites in each of four coldwater trout streams in southeastern Minnesota USA: one site within the residential/commercial areas of a city and one site outside of the city limits in rural (agricultural) areas. Fish were surveyed (all fish counted and identified) in representative 150 to 200 m sections at each stream site with a backpack electrofisher. Data were used to produce Simpson and Shannon diversity indices, taxa richness values, a coldwater index of biotic integrity (IBI) score and rating for each site, and an NMDS plot using fish communities to compare between urban and rural stream sections. Overall, fish representing 17 different species and 11 families were found at the sites examined. Brown trout (Salmo trutta) comprised 65% of the total catch and was the only species collected at every site. Average fish species richness was nearly three times higher at urban sites than at rural sites, and Simpson and Shannon diversities were also significantly (four to five times) higher at urban compared to rural sites. However, coldwater IBI scores were significantly higher at rural (average = 93, good rating) than at urban (average score = 59, a fair rating) sites, indicating better coldwater biotic integrity in rural stream sections. A NMDS plot indicated that fish communities at urban sites were more similar to one another than they were to rural site communities; separation between urban and rural sites was largely influenced by species exclusive to urban sites. Reduced biotic integrity and altered fish community composition in urban streams likely resulted from a combination of factors including modified stream habitat and hydrology, warmer water temperatures, and urban runoff.

Limnological Review doi: 10.3390/limnolrev25040054

Authors: Marcin Weselak Anita Kaliszewicz

The problem of steroid hormones in the aquatic environment remains a current global research topic. These substances have a strong impact on biological processes, contributing to reductions in the populations of numerous fish and amphibian species. The impact of steroid hormones, especially the third-generation progestogens, on aquatic invertebrates is poorly understood. We aimed to determine whether desogestrel, progestogen of low androgenic activity, affects the reproduction and growth of the following freshwater invertebrates: snails of the species Melanoides tuberculata and the planarian Dugesia sp. We also tried to estimate the threshold concentrations of this substance at which significant changes in both the behavior and reproductive activity of the studied organisms are observed. In the mesocosm experiment, we performed three treatments with the following different concentrations of desogestrel: control 0 ng/L, medium 10 ng/L, and high 100 ng/L. The high hormone concentration significantly reduced the reproduction of both snails and planarians, despite their different life history strategies, compared to the control. Both planarians and snails showed a significantly lower abundance in the high concentration compared to the 10 ng/L treatment, indicating a threshold concentration > 10 ng/L. The impacts of steroid hormone pollution on aquatic organisms and the need for further research are discussed.

Limnological Review doi: 10.3390/limnolrev25040053

Authors: Kimio Hirabayashi Masaaki Takeda

Many researchers have used the species composition, relative abundance and distribution pattern of profundal benthic macroinvertebrate communities in particular, especially chironomid fauna, as indicators of the trophic state and pollution of lakes. In addition, compared with previous benthic macroinvertebrate data, it is expected that the process of eutrophication/oligotrophication of lakes can also be traced. Benthic macroinvertebrate distribution was studied in Lake Kawaguchi, Japan (maximum depth 16.1 m; mean depth 9.3 m), on 7 March 2025. The benthic animals identified were aquatic oligochaetes, chironomid larvae, shellfish and others. Differences among environmental factors and zoobenthos densities and rank correlation were analyzed using a non-parametric test. The mean density of oligochaetes, which was the dominant group, was 2457 ± 1247 individuals/m2, followed by chironomid larvae at 816 ± 391 individuals/m2. The larvae of Propsilocerus akamusi were the most abundant species at 669 ± 358 individuals/m2, followed by Chironomus plumosus at 109 ± 114 individuals/m2. Other chironomids (38 ± 75 individuals/m2) were also captured. Benthic communities were collected at all sites, but each taxa had its own characteristics. Oligochaetes and C. plumosus were widely distributed throughout the lake, whereas the distribution of P. akamusi was skewed toward the western part of the lake. In comparison with previous studies, P. akamusi larvae were now found to be the most abundant chironomid species in this lake, accounting for an increased percentage of the chironomid community, while C. plumosus larvae had decreased in recent years. In addition, the higher levels of organic matter in the upper sediment layer of the lake suggest ongoing eutrophication. Previous studies classified Lake Kawaguchi as mesotrophic–eutrophic, but reconsideration of this classification is warranted given the above findings. We suggest that this lake be ranked as a eutrophic lake (chlorophyll-a concentration; ca. 0.05 mg/L) based on a long-term investigation of the changes in chironomid fauna.

Limnological Review doi: 10.3390/limnolrev25040052

Authors: Sebastian Naranjo-Silva Diego Javier Punina-Guerrero Edwin Angel Jacome-Dominguez

The global transition towards renewable energy production has increased the demand for new and more flexible hydropower operations. Although hydropower is generally considered environmentally friendly, it can cause environmental and social impacts. As the biggest and most representative hydropower project in Ecuador, the Coca Codo Sinclair hydropower project (CCSHP) provides a relevant case of water use competition between local communities and the country’s development. In this study, perspectives of four communities near the CCSHP were analyzed through a survey with 183 responses collected in 52 days through door-to-door household visits in two upstream and two downstream towns. The analysis highlights that limited community participation in project design and insufficient communication strategies have undermined public acceptance, despite government promotion of its national benefits. Survey results reveal that 79% of respondents expressed negative perceptions, primarily about environmental change, displacement, and lack of compensation, while only 15% expressed positive views. It is important to note that the communities had no role in selecting the project location, and their involvement was limited, particularly regarding transportation, environmental changes, and the loss of local species. These findings suggest that project managers should strengthen dialogue with local communities and design participatory mechanisms that can improve trust and long-term project acceptance.

Limnological Review doi: 10.3390/limnolrev25040051

Authors: Ana Bianca Pavel Catalina Gavrila Irina Catianis Gabriel Iordache Florina Radulescu Adrian Teaca Laura Dutu

The Mangalia–Limanu coastal lake system, located in southeastern Romania along the Black Sea, represents a transitional aquatic environment shaped by the interplay between freshwater and marine influences. This study provides an integrated assessment of its physicochemical water parameters, sedimentological and geochemical properties, and benthic macroinvertebrate communities, aiming to evaluate its current ecological status and environmental dynamics. Field measurements using a multiparameter sonde revealed a predominantly freshwater to oligohaline system with moderate spatial heterogeneity. DO levels frequently reached supersaturation (>180%), coupled with high pH (~9.1), indicating intense daytime photosynthetic activity. Conductivity, TDS, and salinity increased longitudinally toward the port water area, while nitrate concentrations showed stronger signals upstream. Sediments were dominated by organic matter (18–88%), with lower carbonate (3–53%) and siliciclastic (8–49%) contents. Organic-rich deposits prevailed in the western-central sector, where reduced hydrodynamics and submerged vegetation favor autochthonous organic accumulation, whereas the eastern sector, exposed to marine action, showed more siliciclastic-rich substrates. Geochemical analyses revealed localized exceedances of Cr, Ni, Cu, Zn, and Pb regulatory thresholds (Order 161/2006), suggesting potential contamination hotspots. Benthic communities included 26 taxa, dominated by polychaetas, gammarids, and gastropods, with moderate diversity (H′ < 2). The results highlight a system under moderate anthropogenic pressure but retaining transitional lagoon characteristics, emphasizing the need for continued ecological monitoring and integrated management measures.

Limnological Review doi: 10.3390/limnolrev25040050

Authors: Landry S. Omalanga Ednah K. Onyari

Water is a vital resource for human survival, economic development, and environmental sustainability. It is essential to agriculture, energy production, public health, and biodiversity preservation. Efficient water management is even more important in areas that are prone to scarcity. This paper presents a systematic review of the management of water resources in South Africa, a country characterized by significant water scarcity challenges compounded by its socio-economic and ecological needs. South Africa’s limited freshwater resources are under extreme stress due to its semi-arid climate, unequal rainfall distribution, expanding population, and industrial needs. The nation’s water security has also been made more difficult by historical injustices, climatic fluctuations, and decaying infrastructure. Through a systematic review of 60 scholarly articles published between 2011 and 2025 in the Web of Science database, this study discusses the historical context of water management in South Africa, including the legacy of apartheid-era policies and their impact on access to water. It also examines current management practices, governance structures involving national and local authorities, the role of key institutions such as the Department of Water and Sanitation (DWS), climate change impact on water availability, population growth and urbanization, inequality and access, and challenges in South Africa’s water resources management (WRM). In particular, this review highlights the integration of scientific water quality and biostability assessment into the Integrated Water Resources Management (IWRM) framework in order to produce actionable insights that enhance resilience, sustainability, and equity in WRM. Furthermore, it explores future strategies for sustainable WRM, emphasizing the importance of IWRM, community participation, technological innovation, and climate change adaptation. Through this comprehensive analysis, the paper aims to contribute to a deeper understanding of the complexities and opportunities in ensuring water security for all South Africans.

Limnological Review doi: 10.3390/limnolrev25040049

Authors: Józef Antonowicz Tomasz Wróblewski

In 2023, studies were conducted on volatile organic compounds (VOCs) emitted from the bottom sediments of the mid-forest eutrophic lake. Lake Łętowskie is located in northern Poland and covers an area of 402 hectares. It is part of the “Łętowskie Lake and the vicinity of Kępice” Protected Landscape Area. Bottom sediment samples were collected from five sites located on the lake. The study sites differed in shoreline development: forest, agricultural land, and the central part of the lake. The emissions from the bottom sediment to the atmosphere of 20 volatile organic compounds were measured in the samples using a proton transfer reaction mass spectrometer (PTR-MS). This analytical technique enables the detection and determination of concentrations of volatile organic compounds characterized by proton affinity greater than that of water. The VOC data obtained showed different characteristics for study sites bordering forests and agricultural areas, which was supported by statistical analysis. The VOC data obtained from Lake Łętowskie were compared with results from neighboring lakes, demonstrating similarities to those observed in a lake with a forest catchment area.

Limnological Review doi: 10.3390/limnolrev25040048

Authors: Lucas Galli do Rosário Ricardo Hideo Taniwaki Luis César Schiesari

The growth of the human population, combined with climate change, has made the provisioning of water resources to human populations one of the greatest challenges of recent decades. One commonly adopted solution has been the construction of small dams and reservoirs close to urban settlements. However, concerns have arisen that, despite their small size, small dams may have environmental impacts similar to those known for large dams. The severe water crisis observed between 2014 and 2015 led to the multiplication of small dams in southeastern Brazil, such as the one built on the Fetá stream at the Capivari River basin in the municipality of Louveira. This study aimed to contribute to the assessment of the impacts of small dam construction on water quality by monitoring basic parameters and nutrients during the filling and stabilization period of the Fetá reservoir. As expected, the interruption of water flow and the increase in water residence time led to increases in temperature, pH, electrical conductivity, dissolved oxygen and concentrations of dissolved carbon and nitrogen, as well as a reduction in turbidity. Consistent with the shallow depth of the water column, neither thermal nor chemical stratification was observed. Nevertheless, the water quality of surface and bottom layers was markedly different. Over time, water volume and water quality tended to stabilize. This research clearly demonstrates that small dams and reservoirs cause qualitatively similar environmental impacts to those of large-scale dams and reservoirs worldwide.

Limnological Review doi: 10.3390/limnolrev25040047

Authors: Guillermo Díaz-Martínez Ricardo Navarro-Amador José Luis Sánchez-Salas Deborah Xanat Flores-Cervantes

Access to clean water remains a global challenge, particularly in areas where populations rely on surface water. These water sources must be treated. Coagulation with chemicals causes environmental problems and adverse effects on human health. Natural coagulants obtained from papaya (Carica papaya) waste are presented as an alternative that is safe for human health, non-polluting, and biodegradable. The effectiveness of these natural coagulants is compared to that of aluminum sulfate using jar tests and synthetic and natural surface water, with statistical tools to model treatment processes. All coagulants have competitive results, reaching turbidity remotion levels above 90%. However, in equivalent tested ranges, natural coagulants require lower dosages and perform better with high initial water turbidity due to their polymeric bridging mechanisms and adsorption processes through the action of their functional groups, as detected by FTIR analysis. Additional testing with contaminated water from the Valsequillo dam confirms the use of these coagulants to treat water, with papaya seed coagulant yielding the best results and requiring lower doses, making it a competitive alternative. It can be concluded that papaya-based coagulants obtained from waste can be used as an eco-friendly alternative to aluminum sulfate in physicochemical treatments to purify surface water for human consumption.

Limnological Review doi: 10.3390/limnolrev25040046

Authors: Anastasia Solodkova Sofya Biritskaya Artem Guliguev Diana Rechile Yana Ermolaeva Arina Lavnikova Dmitry Golubets Alyona Slepchenko Ivan Kodatenko Alexander Bashkircev Natalia Kulbachnaya Darya Kondratieva Anna Solomka Dmitry Karnaukhov Eugene Silow

Most studies on microplastic pollution in aquatic ecosystems have focused on the quantitative and qualitative assessment of particles in surface waters. However, the highest concentrations and accumulation of microplastic particles are observed in bottom sediments. The aim of this study was to determine the concentrations of microplastic particles of different morphology in sediments in the beach and littoral zones of Lake Baikal. This study is the first in relation to Lake Baikal to focus specifically on the analysis of microplastic particles in bottom sediments. The results of the study showed that the registered values of concentration of microplastic particles do not exceed the average values for lakes around the world. The predominant type of particles in both the littoral zone and the beach is microplastic fibers. An exception is observed only for one of the locations. This exception is related to the permanent mooring of vessels in this place. Analysis of the types of artificial polymers showed that the microplastic fibers were represented by polyester, and the fragments were represented by alkyd resin (66%), polyvinyl alcohol (32%) and polyvinyl chloride (2%). Shown for the first time in this study, the presence of large numbers of microplastic particles with rare types of artificial polymers suggests that these particles may be under-reported in other studies. The underestimation of particles may be due either to the selection of sampling locations located far from heavily contaminated areas, or to the fragility of these polymers. Although the harm of these types of polymers has not yet been confirmed, the large number of these particles in local areas of lakes should be taken into account. This is due to the large number of organisms, which is usually characteristic of littoral areas, including Lake Baikal, with its diversity of fauna and flora.

Limnological Review doi: 10.3390/limnolrev25030045

Authors: Diego Frau

Different sampling techniques were evaluated to assess potential differences in species richness and the abundances of phytoplankton across several lowland aquatic environments. Five sampling methods were used, including a bucket, narrow- and wide-mouth bottles, a 10 µm plankton net, and a vertical Van Dorn bottle. These sampling methods were applied in subtropical streams, shallow lakes, and rivers. The results were compared using a two-way ANOVA to evaluate differences in total density by considering the morphological group and major phytoplankton phyla. Similarity analyses (SIMPER) and a permutational multivariate analysis of variance (PERMANOVA) were performed to compare the relative abundances of the species. The results showed, in general (except with Cyanophyta, Chrysophyta, and colonies—coenobia), significant differences in the effect of the sampling method but without interaction with the kind of environment. Particularly, the plankton net always reported lower density estimations, with the bucket having the highest values and the wide–narrow bottle methods having similar values. SIMPER and PERMANOVA indicated differences, especially with the plankton net and the other methods, particularly the bucket. These findings suggest that the sampling method can influence species counts and registration in subtropical water ecosystems, highlighting the need for standardized procedures across countries to obtain comparable and reliable results.

Limnological Review doi: 10.3390/limnolrev25030044

Authors: Kshyana Prava Samal Rakesh Ranjan Thakur Alok Kumar Panda Debabrata Nandi Alok Kumar Pati Kumarjeeb Pegu Bojan Đurin

Access to clean drinking water is crucial for any region’s social and economic growth. However, rapid urbanization and industrialization have significantly deteriorated water quality, posing severe pollution threats from domestic, agricultural, and industrial sources. This study presents an innovative framework for assessing water quality in North Bhubaneswar, integrating the Water Quality Index (WQI) with statistical analysis, geospatial technologies, and machine learning models. The WQI, calculated using the Weighted Arithmetic Index method, provides a single composite value representing overall water quality based on several key physicochemical parameters. To evaluate potable water quality across 21 wards in the northern zone, several key parameters were monitored, including pH, electrical conductivity (EC), dissolved oxygen (DO), hardness, chloride, total dissolved solids (TDSs), and biochemical oxygen demand (BOD). The Weighted Arithmetic WQI method was employed to determine overall water quality, which ranged from excellent to good. Furthermore, Principal Component Analysis (PCA) revealed a strong positive correlation (r > 0.6) between pH, conductivity, hardness, and alkalinity. To enhance the accuracy and reliability of water quality assessment, multiple machine learning models Logistic Regression (LR), Decision Tree (DT), Random Forest (RF), Support Vector Machine (SVM), K-Nearest Neighbors (KNN), and Naïve Bayes (NB) were applied to classify water quality based on these parameters. Among them, the Decision Tree (DT) and Random Forest (RF) models demonstrated the highest precision (91.8% and 92.7%, respectively) and overall accuracy (91.7%), making them the most effective in predicting water quality and integrating WQI, machine learning, and statistics to analyze water quality. The study emphasizes the importance of continuous water quality monitoring and offers data-driven recommendations to ensure sustainable access to clean drinking water in North Bhubaneswar.

Limnological Review doi: 10.3390/limnolrev25030043

Authors: Cortney Cameron

With mounting anthropogenic pressures on groundwater supplies, practical methods for quantifying lake–groundwater exchange are critical for water resources management. This is particularly important in karst environments where surface–groundwater connectivity is often high. The White method uses nighttime water level fluctuations to estimate groundwater flux. While the White method has been applied to flooded wetlands, published lake applications are rare. This study evaluated a modified White method for estimating leakage at 28 karst lakes in Florida. The method was modified to include evaporation correction, with both nighttime and all-day approaches evaluated. Using the nighttime correction approach, average annual groundwater flux (leakage) ranged from −2.4 to +1.9 m/y, with a mean of −0.5 m/y (negative indicates lake outflow). Without nighttime evaporation correction, leakage estimates would be erroneous by an average of −0.7 m/y. The results showed no significant difference from 138 leakage values compiled from previous studies that used diverse methods. The modified White method requires special attention to evaporation, filtering criteria, and hydrogeologic context. Overall, the method provides a useful complementary approach to other methods for estimating long-term annual lake–groundwater exchange with comparatively minimal data requirements.

Limnological Review doi: 10.3390/limnolrev25030042

Authors: Jesús Barrera-Rojas Carlos Vladimir Muro-Medina Hasbleidy Palacios-Hinestroza Valentín Flores-Payán Daryl Rafael Osuna-Laveaga Belkis Sulbarán-Rangel

The growing global population and increasing water demand have intensified the urgency for efficient wastewater treatment strategies to address environmental pollution and water scarcity. Physicochemical treatment technologies remain among the most widely implemented solutions due to their high removal efficiency, operational simplicity, and relatively low cost. These processes effectively target a broad spectrum of contaminants—including suspended solids, heavy metals, recalcitrant organic compounds, and high salinity—through unit operations such as coagulation, flocculation, adsorption, and filtration. Nevertheless, they often generate concentrated waste streams that present significant disposal and environmental challenges. Applying these technologies within a circular economy framework enables wastewater reuse, resource recovery, and a reduced environmental impact. Circular strategies enable the recovery and reuse of water, energy, and materials, converting waste into valuable resources. Treated water can be safely reused, while by-products such as biogas and nutrients (e.g., phosphorus, nitrogen, and organic carbon) can be recovered and reintegrated into agricultural and industrial processes. Furthermore, advanced methods such as membrane separation and electrochemical treatments allow for the selective recovery of high-value metals. This review analyzes key physicochemical technologies for wastewater treatment and evaluates their integration into circular economy models, with a focus on waste valorization, resource recovery, and environmental impact reduction. By adopting circular approaches, wastewater treatment systems can enhance sustainability, improve economic performance, and contribute to achieving the global water and sanitation target.

Limnological Review doi: 10.3390/limnolrev25030041

Authors: Markus Heinrichs

Saline lakes are distinct, understudied aquatic ecosystems, particularly those that are hydrologically isolated from marine environments. In British Columbia (BC), Canada, the scope and trajectory of scientific research on these systems remain largely undocumented. To address this gap, a meta-analysis was conducted of peer-reviewed scholarly articles focusing on both coastal and inland saline lakes to identify the primary research themes and assess temporal trends in scientific inquiry. The coastal meromictic lakes Sakinaw and Powell were included because of their retention of relict marine waters. Thematic areas of research spanned a diverse array of disciplines, including paleolimnology, neolimnology, halophilic insect and plant ecology, microbial diversity, and functional genomics, as well as astrobiology as analog environments for extraterrestrial life. Temporal analysis revealed variable research intensity across disciplines: the number of paleolimnological training sets has declined, whereas microbial genomics and astrobiological analog investigations have increased. Among inland saline lakes, Mahoney Lake, Pavilion Lake, and various saline lakes within the Cariboo region emerged as key sites of ecological and geochemical interest. This synthesis highlights both the ecological significance and scientific potential of BC’s saline lakes while underscoring the need for more systematic and interdisciplinary research to better understand their roles in broader environmental and evolutionary contexts.

Limnological Review doi: 10.3390/limnolrev25030040

Authors: Ivan Kirvel Ainur Zhidebayeva Lyailim Taizhanova Ainazhan Aitimova Samal Syrlybekkyzy Akmaral Serikbayeva Kamshat Jumasheva Symbat Koibakova

The following reference was retracted, and therefore its citation was removed from this manuscript [...]

Limnological Review doi: 10.3390/limnolrev25030039

Authors: Zahra Ghaffari Abdel Rahman Awawdeh Greg Easson Lance D. Yarbrough Lucas James Heintzman

Groundwater depletion poses a critical challenge to global water security, threatening ecosystems, agriculture, and sustainable development. The Mississippi Delta, a region heavily reliant on groundwater for agriculture, has experienced significant groundwater level declines due to intensive irrigation. Traditional in situ monitoring methods, while valuable, lack the spatial coverage necessary to capture regional groundwater dynamics comprehensively. This study addresses these limitations by leveraging downscaled Gravity Recovery and Climate Experiment (GRACE) data to estimate groundwater levels using random forest modeling (RFM). We applied a machine-learning approach, utilizing the “Forest-based and Boosted Classification and Regression” tool in ArcGIS Pro, (ESRI, Redlands, CA) to predict groundwater levels for April and October over a 10-year period. The model was trained and validated with well-water level records from over 400 monitoring wells, incorporating input variables such as NDVI, temperature, precipitation, and NLDAS data. Cross-validation results demonstrate the model’s high accuracy, with R2 values confirming its robustness and reliability. The outputs reveal significant groundwater depletion in the central Mississippi Delta, with the lowest water level observed in the eastern Sunflower and western Leflore Counties. Notably, April 2014 recorded a minimum water level of 18.6 m, while October 2018 showed the lowest post-irrigation water level at 54.9 m. By integrating satellite data with machine learning, this research provides a framework for addressing regional water management challenges and advancing sustainable practices in water-stressed agricultural regions.

Limnological Review doi: 10.3390/limnolrev25030038

Authors: Sabine Sherrin Yulia Shcherbakova John S. Richardson

Alpine streams are particularly vulnerable to climate change and in many parts of the world are poorly studied, which is true of western North America. We sampled the invertebrate communities and measured the physico-chemical parameters of nine small streams in a single alpine meadow. There was a wide variation in the physico-chemical variables in this single, small catchment. Three variables were selected based on their high loadings from principal component analysis, and these were slope, width and pH. There were relations between densities of some of the benthic organisms and the three main environmental gradients. We found large variation in densities (595 to 7340 individuals m−2) and diversity of benthic communities across a small gradient of physico-chemical variation in these nine streams in a single alpine meadow. High beta diversity (most > 0.8) between streams indicated substantial differences in community structure and diversity in a small area of about 1 km. These results suggest strong environmental filters on communities in these alpine stream systems and the potential for high regional biodiversity far beyond what individual streams support.

Limnological Review doi: 10.3390/limnolrev25030037

Authors: Terencio Rebello de Aguiar Junior Lafayette Dantas da Luz Reginaldo da Silva Rangel Neto Diogo Caribé de Sousa Eduardo Mariano-Neto

This study presents a methodological framework for prioritizing areas for forest restoration with the primary objective of enhancing water provision. A multi-scale approach was employed, starting with macro-scale criteria at the river basin level, followed by more localized landscape and hydro-ecological assessments. This two-stage process facilitated strategic planning for interventions aimed at restoring forest cover in permanent preservation areas (PPAs) along watercourses and springs. The methodology was applied to the Joanes and Jacuípe Rivers Permanent Protection Areas Forest Rehabilitation Project in the Salvador Metropolitan Region, Bahia. The project’s primary goal is to improve water security by restoring native vegetation across 100 springs and 100 hectares of riparian zones, which are critical to the water supply system for the Salvador Metropolitan Region. The prioritization process integrated hydrological, ecological, and socio-environmental criteria, ensuring that restoration efforts not only enhance water production but also provide long-term ecological and social benefits.

Limnological Review doi: 10.3390/limnolrev25030036

Authors: Ivan Martinić Ivan Čanjevac

During the period from 2020 to 2024, 900 springs were mapped on the southern slopes of Medvednica Mountain Nature Park. Physicochemical parameters (temperature, pH, and electrical conductivity) were measured at 701 of these springs using a portable multimeter, and results were analyzed in relation to local lithology and human activities. This research provides the first results of this kind in this study area, aiming to expand the knowledge on local springs and to support the future protection and management of spring ecosystems. Springs on the Medvednica mountain showed substantial variation in measured parameters. The temperature ranged from 3.4 to 18.9 °C, reflecting local hydrological conditions, aquifer characteristics, and seasonal variability. Electrical conductivity (EC) ranged between 41 μS/cm and 2062 μS/cm, determined by both hydrogeological settings and anthropogenic impacts such as winter road salting. The pH values showed moderate variability, remaining mostly within neutral levels. These results emphasize the importance of continued monitoring and further research of Medvednica springs, in order to highlight their importance and to preserve their ecological and hydrological roles.

Limnological Review doi: 10.3390/limnolrev25030035

Authors: Maria Kofidou Vasilios Ampas

Aquatic vegetation plays a crucial role in freshwater ecosystems by providing habitats, regulating water quality, and supporting biodiversity. This study aims to monitor and analyze the dynamics of aquatic vegetation in Chimaditida Shallow Lake, Greece, using Sentinel-2 satellite imagery, with validation from field measurements. Data processing was performed using Google Earth Engine and QGIS. The study focuses on discriminating and mapping two classes of aquatic surface conditions: areas covered with Floating and Emergent Aquatic Vegetation and open water, covering all seasons from 1 March 2024, to 28 February 2025. Spectral bands such as B04 (red), B08 (near infrared), B03 (green), and B11 (shortwave infrared) were used, along with indices like the Modified Normalized Difference Water Index and Normalized Difference Vegetation Index. The classification was enhanced using Otsu’s thresholding technique to distinguish accurately between Floating and Emergent Aquatic Vegetation and open water. Seasonal fluctuations were observed, with significant peaks in vegetation growth during the summer and autumn months, including a peak coverage of 2.08 km2 on 9 September 2024 and a low of 0.00068 km2 on 28 December 2024. These variations correspond to the seasonal growth patterns of Floating and Emergent Aquatic Vegetation, driven by temperature and nutrient availability. The study achieved a high overall classification accuracy of 89.31%, with producer accuracy for Floating and Emergent Aquatic Vegetation at 97.42% and user accuracy at 95.38%. Validation with Unmanned Aerial Vehicle-based aerial surveys showed a strong correlation (R2 = 0.88) between satellite-derived and field data, underscoring the reliability of Sentinel-2 for aquatic vegetation monitoring. Findings highlight the potential of satellite-based remote sensing to monitor vegetation health and dynamics, offering valuable insights for the management and conservation of freshwater ecosystems. The results are particularly useful for governmental authorities and natural park administrations, enabling near-real-time monitoring to mitigate the impacts of overgrowth on water quality, biodiversity, and ecosystem services. This methodology provides a cost-effective alternative for long-term environmental monitoring, especially in regions where traditional methods are impractical or costly.

Limnological Review doi: 10.3390/limnolrev25030034

Authors: Franca Sangiorgio Daniela Santagata Fabio Vignes Maurizio Pinna Alberto Basset

The availability of detritus is a key factor influencing aquatic biota and can significantly affect decomposition processes. In this study, we investigated how varying quantities of surrounding detritus impact leaf litter decay rates. It was tested in flowing and still-water microcosms to highlight context-dependent effects of surrounding detritus on leaf litter decomposition. To isolate the effect of detritus amount, experiments were conducted in laboratory microcosms simulating lotic and lentic ecosystems, each containing leaf fragments for decomposition assessments. Four detritus quantities were tested, with invertebrates either allowed or restricted from moving among detritus patches. Leaf decomposition rates were influenced by the amount of surrounding detritus, with slower decay observed at higher detritus conditions, regardless of invertebrate mobility. Detritivore distribution responded to both detritus quantity and oxygen availability, showing a preference for high detritus conditions. Additionally, detritus quantity affected microbial activity with a quadratic response, as indicated by leaf respiration rates. Overall, our findings indicate that the amount of surrounding detritus modulates leaf litter decomposition independently of invertebrate density, by influencing oxygen dynamics and, consequently, the activity of biological decomposers.

Limnological Review doi: 10.3390/limnolrev25030033

Authors: Cinthya Soledad Manjarrez-Rangel Silvana Raquel Halac Luciana Del Valle Mengo Eduardo Luis Piovano Gabriela Ana Zanor

Eutrophication has intensified in lacustrine systems across the American continent, which has been primarily driven by human activities such as intensive agriculture, wastewater discharge, and land-use change. This phenomenon adversely affects water quality, biodiversity, and ecosystem functioning. However, studies addressing the historical evolution of trophic states in lakes and reservoirs remain limited—particularly in tropical and subtropical regions. In this context, sedimentary records serve as invaluable archives for reconstructing the environmental history of water bodies. Paleolimnological approaches enable the development of robust chronologies to further analyze physical, geochemical, and biological proxies to infer long-term changes in primary productivity and trophic status. This review synthesizes the main methodologies used in paleolimnological research focused on trophic state reconstruction with particular attention to the utility of proxies such as fossil pigments, diatoms, chironomids, and elemental geochemistry. It further underscores the need to broaden spatial research coverage, fostering interdisciplinary integration and the use of emerging tools such as sedimentary DNA among others. High-resolution temporal records are critical for disentangling natural variability from anthropogenically induced changes, providing essential evidence to inform science-based lake management and restoration strategies under anthropogenic and climate pressures.

Limnological Review doi: 10.3390/limnolrev25030032

Authors: Maribeb Castro-González Verónica Molina

In this study, we evaluated the nitrous oxide production potential of denitrifying bacterial strains isolated from sediments of the urban wetland Santa María del Lago under anaerobic and aerobic conditions to determine their potential role in mitigating anthropogenic N2O emissions, which have increased by approximately 40% since 1980, and if these emissions could be related to the absence of the nitrous oxide reductase gene (nosZ). The results demonstrated that denitrifying bacteria belonging to the genus Bacillus were able to generate nitrous oxide in high concentrations under both aerobic (up to 83 nM/h) and anaerobic (up to 3865.5 nM/h) conditions in cultures with optimal concentrations of nitrate and carbon. The amplification of the nosZ gene as marker of denitrifying microorganisms showed that only 50% of strains possess this gene, and its presence did not correlate with nitrous oxide reduction under anoxic conditions. Interestingly, one strain was able to reduce nitrous oxide in the presence of air, which is promising for its potential use in aerobic bioremediation systems that require microorganisms with a high affinity for this greenhouse gas to reduce emissions into the atmosphere.

Limnological Review doi: 10.3390/limnolrev25030031

Authors: Ekaterina Sorokovikova Irina Tikhonova Galina Fedorova Nadezhda Chebunina Anton Kuzmin Maria Suslova Yanzhima Naidanova Sergey Potapov Andrey Krasnopeev Anna Gladkikh Olga Belykh

Microcystis, a potentially toxigenic cyanobacterium known to form extensive blooms in eutrophic lakes globally, was investigated in the cold oligotrophic Lake Baikal. We report the isolation of two Microcystis strains, Microcystis aeruginosa and M. novacekii, and document the presence of the latter species in Lake Baikal for the first time. In M. aeruginosa strain BN23, we detected the microcystin synthetase gene mcyE. Liquid chromatography-mass spectrometry revealed the presence of two microcystin variants in BN23, with microcystin-LR, a highly potent toxin, being the dominant form. The concentration of MC-LR reached 540 µg/g dry weight. In contrast, M. novacekii strain BT23 lacked both microcystin synthesis genes and detectable toxins. The habitat waters were characterized as oligotrophic with minor elements of mesotrophy, exhibiting low phytoplankton biomass dominated by the chrysophyte Dinobryon cylindricum (76–77% of biomass), with cyanobacteria contributing 8–10%. The contribution of Microcystis spp. to the total phytoplankton biomass could not be quantified as they were exclusively found in net samples. The water temperature at both sampling stations was ~19 °C, which is considerably lower than optimal for Microcystis spp. and potentially conducive to enhanced microcystin production in toxigenic genotypes.

Limnological Review doi: 10.3390/limnolrev25030030

Authors: Anne Leung Emma Rowan Flavia Melati Chiappara Konstantinos Grintzalis

Humanity faces the great challenges arising from pollution and climate change which evidently lead to the irreversible effects observed on the planet. It is now more important than ever to monitor and safeguard the ecosystem as it has been highlighted by governments and scientists. Conventional approaches for water pollution rely on the detection of chemicals in the environment. However, these descriptive observations when compared against water quality standards used as metrics for pollution are unable to predict pollution early or capture the extent of its impact. This weakness is reflected in the legislation and the thresholds for emerging pollutants such as pharmaceuticals and nanomaterials. To bridge the gap and to understand the underlying mechanisms for toxicity, research in the field of molecular ecotoxicology shifts more and more towards the integration of model systems, in silico approaches and molecular information as endpoints. Focusing on the freshwater ecosystem, daphnids are key species employed in risk assessment which are characterised as highly responsive to pollutants and physical stressors. The translation of molecular information describing the physiology of these organisms provides novel and sensitive metrics for pollution assessment.

Limnological Review doi: 10.3390/limnolrev25030029

Authors: Marco Antonio Cordero Mancilla Wilmer Moncada Vinie Lee Silva Alvarado

Predicting water losses and final storage in reservoirs has become increasingly relevant in the efficient control and optimization of water provided to agriculture, livestock, industry, and domestic consumption, aiming to mitigate the risks associated with flash floods and water crises. This research aims to develop a new Machine Learning (ML) algorithm based on a water balance model to simulate the outflow in the Cuchoquesera reservoir in the Ayacucho region. The method uses TensorFlow (TF), a powerful interface for graphing and time series forecasting, for data analysis of hydrometeorological parameters (HMP), inflow (QE_obs), and outflow (QS_obs) of the reservoir. The ML water balance model is fed, trained, and calibrated with daily HMP, QE_obs, and QS_obs data from the Sunilla station. The results provide monthly forecasts of the simulated outflow (QS_sim), which are validated with QS_obs values, with significant validation indicators: NSE (0.87), NSE-Ln (0.83), Pearson (0.94), R2 (0.87), RMSE (0.24), Bias (0.99), RVB (0.01), NPE (0.01), and PBIAS (0.14), with QS_obs being slightly higher than QS_sim. Therefore, it is important to highlight that water losses due to evaporation and infiltration increased significantly between 2019 and 2023.

Limnological Review doi: 10.3390/limnolrev25030028

Authors: Neal D. Mundahl John Howard

Lake Winona, a 129 ha eutrophic urban lake comprised of two interconnected basins, exceeds state water quality standards for total phosphorus. Historical lake nutrient data and traditional watershed modeling for the lake’s two basins highlighted multiple major pathways (e.g., municipal stormwater discharges, watershed runoff, internal loading, and wetland discharges) for total phosphorus (P) loading, with >900 kg P/year estimated entering the water columns of each basin. Updated data sources and newer watershed modeling resulted in significantly different (both higher and lower) P loading estimates for the various P sources, especially watershed runoff and internal loading. Overall, basin-specific loading estimates using the updated model were significantly lower (28–40%) than previous estimates: 680 and 546 kg P/year mobilized in the western and eastern basins, respectively. To achieve state water quality standards (<60 ppm P for the western basin, <40 ppm for the eastern basin), watershed and internal P loading each would need to be reduced by approximately 120 kg P/year across the two basins. Reductions could be achieved by a combination of alum treatments to reduce internal loading, removal of common carp (Cyprinus carpio) to prevent interference with alum treatments and nutrient releases via excretion and defecation, and six engineered structures to intercept P before it enters the lake. The different P reduction projects would cost USD 119 to 7920/kg P removed, totaling USD 5.2 million, or USD 40,310/hectare of lake surface area.

Limnological Review doi: 10.3390/limnolrev25020027

Authors: Kimio Hirabayashi

The dipteran family Chironomidae is the most widely distributed and, frequently, the most abundant group of insects in freshwater environments. Ecologically, the group plays an important role in trophic cycles and detritus processing in aquatic ecosystems and can be the most productive group of secondary producers in running waters. The annual secondary production of Chironomidae was estimated using emergence trap data from riffles and pools from two stations on the middle reaches of the Shinano River: Tokida Bridge Area (slope 1/180) and Iwano Bridge Area (1/1000). Emergence traps were set up for 24 h on the river’s water surface at three points each in the riffles and pools monthly from April 2015 to March 2019. Five subfamilies of Chironomidae were recorded during the investigation period: Chironominae, Orthocladiinae, Tanypodinae, Diamesinae, and Prodiamesinae. In the Shinano River (Tokida + Iwano area), Orthocladiinae and Diamesinae were the dominant subfamilies in terms of both density (63.2% and 19.0%, respectively) and biomass (62.2% and 25.2%, respectively). Each year’s annual secondary production measured as ash free dry weight (AFDW) was 11.33–55.04 g/m2/year in Tokida and 5.83–38.43 g/m2/year in Iwano. The average annual secondary production of detritus feeder Chironomidae (all except for Tanypodinae) was 24.46 ± 20.38 (ranging from 11.13 in 2015 to 54.67 in 2018) in the Tokida area and 19.61 ± 16.38 (ranging from 5.41 in 2016 to 37.53 in 2017) in the Iwano area. On the other hand, that of carnivorous Chironomidae (Tanypodinae) was 0.22 ± 0.10 (ranging from 0.13 in 2016 to 0.37 in 2018) in the Tokida area and 0.66 ± 0.24 (ranging from 0.42 in 2016 to 0.90 in 2017) in the Iwano area, and overall secondary production averaged 22.48 g/m2/year in the middle reaches of the Shinano River. These values were higher than in previous reports.

Limnological Review doi: 10.3390/limnolrev25020026

Authors: Nina Sukhovilo Daria Vlasova Aliaksei Novik Boris Vlasov

This article describes the reasons for and trends in the overgrowth of soft-water lakes in Belarus. Due to their unique water properties (low mineralization, pH, and nitrogen and phosphorus concentrations) and high water transparency, soft-water lakes are home to protected plant species like Lobelia dortmanna L., Isöetes lacustris L., and Littorella uniflora L. The purpose of this study was to analyze changes in aquatic vegetation distribution in seven soft-water Belarusian lakes and identify the causes of these changes. The initial data for this research were the results of field observations, the archive materials of the research laboratory of lake research conducted by the Belarusian State University for the period from 1971 to 2016, including morphometric and hydrochemical parameters, the characteristics of catchments and water exchange, and the results of studying the species composition and distribution of aquatic vegetation. The authors’ field studies were carried out in 2022–2024. We used expeditionary, hydrochemical, cartographic, and comparative research methods. The most significant changes in overgrowth were observed in Lakes Svityaz and Beloe (Luninets District). These lakes have high recreational loads. Significant negative trends were also noted in Lakes Bolshoe Ostrovito and Bredno. Over 35 years, the depth of distribution of submerged macrophytes in Lake Svityaz has decreased from 7 to 2 m, and the abundance and projective cover of semi-submerged macrophytes have increased. In Lake Beloe, I. lacustris, which forms a tier of submerged plants, has almost completely disappeared, and a previously absent strip of air-aquatic plants has formed. The total area of overgrowth in the lake has decreased from 35% of the water area to 3.2%. In Lake Bolshoe Ostrovito, Fontinalis sp., previously common at depths of up to 5 m, has practically disappeared. In Lake Bredno, the water moss Drepanocladus has spread to a depth of 4 m. In Lake Glubokoe, a new area of I. lacustris growth was discovered around an island at depths of up to 4 m. In Lake Cherbomyslo, the decrease in the species’ depth and area of distribution is associated with a weakening of the inflow of bog waters due to their backwater. The main causes of these changes are largely due to anthropogenic factors (water pollution by biogenic compounds) and, to a lesser extent, hydrological changes (decrease in the moisture content of lake catchments).

Limnological Review doi: 10.3390/limnolrev25020025

Authors: Daniela Resende Duque Adriano Gonçalves dos Reis Jorge Kennety Silva Formiga Suzelei Rodgher

To reduce the concentration of phosphorus, the main nutrient responsible for eutrophication, two adsorbents were tested: a commercial activated carbon and one produced from the pods of Moringa oleifera. A concentrated phosphorus solution representative of eutrophic ecosystems was produced at 0.210 mg·L−1 and used as the adsorbate. Thirty-nine laboratory samples were prepared with adsorbent dosages ranging from 0.5 g∙L−1 to 2.0 g∙L−1, and statistical analyses were applied to evaluate the results. An increase in the concentration of phosphorus in the solution was detected in all the tests. Desorption occurred due to the presence of nutrients in the composition of the adsorbents, in addition to the mild physical activation and the use of H3PO4 as a chemical activator of the natural adsorbent, which further favored desorption at equilibrium, even for activated carbon. This work, therefore, highlights the limitations of using the adsorption technique to remove phosphorus from eutrophic aquatic ecosystems. It is recommended that other activation methods for M. oleifera pods be studied for phosphorus removal from water, as well as adsorption equilibrium, kinetics, and thermodynamic studies.

Limnological Review doi: 10.3390/limnolrev25020024

Authors: Nathália Rodrigues Igor C. Miyahira Antonio J. S. Rodrigues Luciano N. Santos Raquel A. F. Neves

Freshwater bivalves play essential ecological roles in ecosystems, but they are among the most threatened fauna worldwide. Despite receiving industrial and domestic wastes, the Guandu River is the main source of drinking water for more than nine million people in the Rio de Janeiro metropolitan region. This study aimed to assess how infaunal bivalves respond to water and sediment quality in the Guandu River basin. Samples were collected at 10 sites across reservoirs, lotic, and lentic systems during cold–dry and warm–rainy seasons. Four bivalves were identified: Anodontites trapesialis, Diplodon ellipticus, Corbicula fluminea (non-native), and C. largillierti (non-native). Native species were restricted to two lentic sites at Guandu Lagoon, with the poorest environmental quality, significantly affected by high chlorophyll a and ammonia in the water. In contrast, C. fluminea was widely distributed and more abundant in the basin but restricted to less degraded sites, suggesting a lower tolerance to environmental pollution. Multivariate analyses indicated significant differences in environmental conditions and species–environment correlation. The non-native species spread and poor environmental quality threaten native bivalves in the Guandu River basin, leading them to a local extinction risk. Results highlight the need for effective management and conservation actions to protect biodiversity in tropical river basins.

Limnological Review doi: 10.3390/limnolrev25020023

Authors: Biswajit Patra Mihir Tanay Das Surya Narayan Pradhan Soumya Ranjan Dash Prajna Paramita Bhuyan Biswajita Pradhan

Ferrochrome pollution, a by-product of the ferroalloy industry, is emerging as a significant environmental concern due to its potential to contaminate groundwater resources. This contamination occurs primarily through the leaching of heavy metals, such as chromium, into the soil and water systems. This review article presents a strategic framework for assessing environmental and health risks associated with the ferrochrome industry pollution rather than focusing on a case study. The suggested methodology is designed to guide future field investigations in areas impacted by ferrochrome industrial activities. The presence of chromium in groundwater poses serious risks to both ecosystems and human health. In aquatic ecosystems, elevated chromium levels can disrupt the balance of microbial communities, affect biodiversity, and harm aquatic organisms. For humans, long-term exposure to chromium-contaminated groundwater is associated with a range of health issues, including carcinogenic effects, skin rashes, respiratory problems, and potential damage to vital organs. The widespread use of groundwater for drinking, irrigation, and industrial purposes exacerbates the risks to public health. This paper explores the sources, pathways, and mechanisms of ferrochrome contamination, examines its impact on groundwater ecosystems, and highlights the health consequences for affected populations. Strategies for mitigating ferrochrome pollution, including treatment technologies and policy interventions, are also discussed to help safeguard both environmental and public health.

Limnological Review doi: 10.3390/limnolrev25020022

Authors: Michel Biondi Larissa Langsdorff Pimenta Gabriela Costa Rodrigues Gustavo Pereira Lima Marcelo Gomes Marçal Vieira Vaz Flávia de Freitas Coelho

The study evaluated the vegetative growth and reproductive strategies of the macrophyte Pistia stratiotes under varying nutrient (carbon and nitrogen) and light (full sun and 70% shade) conditions, as well as its epiphytic association with heterocytous cyanobacteria. Plants were collected from a reservoir, transferred to a greenhouse, and subjected to six treatments, with sampling every 15 days. Clonal growth was higher in nitrogen-supplemented treatments, while flowering was more pronounced in carbon-supplemented treatments. Heterocyte production by epiphytic cyanobacteria on roots positively correlated with P. stratiotes total biomass, suggesting the macrophyte utilizes nitrogen fixed by periphytic cyanobacteria. The results highlight the importance of nitrogen and carbon for growth and reproduction, with distinct resource allocation for rosettes (nitrogen) and flowers (carbon). The P. stratiotes-cyanobacteria association may enhance macrophyte population expansion, underscoring the ecological role of these microorganisms.

Limnological Review doi: 10.3390/limnolrev25020021

Authors: Beatriz Guedes-Pereira Romeu Randefran Souza Dantas Juliana Mendonça Silva de Jesus Isabela Gagliardi Ortiz Gabrielle Segatti Soares Almeida Rodrigo de Freitas Bueno Luís César Schiesari Ricardo Hideo Taniwaki

Water quality in urban streams is closely linked to socioeconomic conditions, particularly in densely populated and poorly sanitized areas. This study evaluates the physicochemical and microbiological quality of water in the Billings-Tamanduateí sub-basin and investigates its correlation with social indicators such as population density, informal settlements, and lack of sewage treatment. Water samples were collected from 14 sub-basins, analyzing parameters, including dissolved organic and inorganic carbon, total dissolved nitrogen, pH, dissolved oxygen, oxidation-reduction potential, conductivity, and the presence of enterobacteria (Escherichia coli, Enterococcus, and Pseudomonas aeruginosa). Statistical analyses revealed strong associations between water quality degradation and increased population density, lack of sanitation, and lower per capita income. The findings reinforce that socially vulnerable areas are the most affected, with higher levels of organic and microbiological contamination. Despite improvements in sewage collection over time, gaps in wastewater management persist, even in major metropolitan areas such as São Paulo. Future studies could expand the analysis to include less vulnerable regions for comparison and explore the impacts of climate change on urban stream water quality. The results highlight the urgent need for improved sanitation infrastructure and policies to mitigate contamination and protect public health.

Limnological Review doi: 10.3390/limnolrev25020020

Authors: Atiqur Rahman Sunny Sharif Ahmed Sazzad Md Shishir Bhuyian Md. Nazmul Hasan Md. Faruque Miah Md. Ashrafuzzaman Shamsul Haque Prodhan

Background: Bangladesh’s wetlands support fish genetic resources, biodiversity, and food security but face obstacles like habitat degradation, overfishing, and climate change. This research looks at the diversity, abundance, IUCN conservation status, and stakeholder views for sustainable wetland management in three major wetlands: the Sundarbans mangrove (brackish water), the Sylhet floodplain (freshwater), and the Meghna River basin (estuary). Methods: To assess ecosystem health and vulnerability, we assess fish biodiversity and conservation status using Margalef’s Species Richness Index and Shannon–Weaver Diversity Index. We also used structured questionnaires to interview and gain stakeholders’ perceptions. Results: A total of 165 fish species were identified and categorized based on the IUCN Red List. The Sundarbans exhibited the highest species richness and diversity. The proportion of vulnerable species was highest in Sylhet (15%), followed by the Sundarbans (12%) and Meghna (9%), while 54% of fish species in Sylhet, 36% in the Sundarbans, and 26% in Meghna were not threatened. This study emphasizes integrated wetland management solutions that support SDGs 2 (Zero Hunger), 14 (Life Below Water), and 15 (Life on Land) as outlined by the Food and Agriculture Organization (FAO). Conclusion: Findings provide a foundation for policymakers, researchers, and conservationists to develop sustainable wetland management frameworks that safeguard fish genetic resources, livelihoods, and ecological balance.

Limnological Review doi: 10.3390/limnolrev25020019

Authors: Valentina Battistelli Leonardo Brustenga Gianandrea La Porta Mattia Baccianella Livia Lucentini

The frequencies of both micronuclei (Mn) and nuclear abnormalities (NAs) were determined in peripheral blood smears of European perch (Perca fluviatilis), rudd (Scardinius erythrophthalmus), and pikes (genus Esox) from Lake Piediluco (Central Italy). Given the conformation of the lake, all the animals from the three species were equally exposed to the same natural stressors. To assess the different stress responses in the three species, 20 blood smears per specimen from each species were analyzed, counting the micronuclei and nuclear aberration present over a total of 1000 erythrocytes for each slide. Different responses to stress were recorded in the three species, with P. fluviatilis exhibiting the least amount of both Mn (0.42%) and NAs (0.01%), and therefore the better homeostasis, while the majority of Mn and NAs were recorded in Esox spp. (Mn: 3.88%; NAs: 23.18%). No MN were observed in S. erythrophthalmus, so that might not be an adequate species to apply the micronucleus test, and it also presented a lower percentage of NAs (15.32%) compared to the pike samples. This work provides, for the first time, baseline values of erythrocyte micronuclei and nuclear aberration from natural populations of the three fish species in a lake from Central Italy.

Limnological Review doi: 10.3390/limnolrev25020018

Authors: Barbara de Fátima Oliveira da Silva Antonio Rafael Gomes de Oliveira João Victor de Moraes Souza Pinheiro Brenda Ribeiro Padilha da Silva Remo Luan Marinho da Costa Pereira Luci Cajueiro Carneiro Pereira Rauquírio Marinho da Costa

The present study investigated the gut contents of oysters cultivated in the Emboraí Velho Estuary (Amazonian littoral), focusing on the analysis of diatoms. Analyses of the stomach contents from 60 adult individuals of the species Crassostrea gasar (Adanson, 1757) collected in the study environment were performed. Additional water samples were collected for the analysis of diatoms present in the estuary. The total number of diatom taxa identified in the estuary was 123, with 35.8% centric diatoms and 64.2% pennate diatoms. Organisms recorded in the analyzed oyster stomachs comprised 61 taxa, of which 37.7% were centric and 62.3% pennate diatoms. The relative abundance of Cymatosira belgica Grunow was 78.2% in April, 72.1% in June, 51.9% in September, and 91.8% in December in the estuary. However, in the gut content, it was 9.9% in April, 4.3% in June, 13.9% in September, and 45.1% in December. The relative abundance of C. belgica, as well as of other less abundant species, was not similar between the gut contents and the diatom species identified in the estuary. Our results indicate that cultivated oysters selectively feed on certain diatom species identified in the estuary, as the main species recorded in the gut contents were not similar to the most abundant and frequent species found in the estuary during the same months of the present study.

Limnological Review doi: 10.3390/limnolrev25020017

Authors: Adriano Teixeira de Oliveira Ariany Rabello da Silva Liebl Maria Fernanda da Silva Gomes Maiko Willas Soares Ribeiro Rayana Melo Paixão Antônia Jaqueline Vitor Paiva Suelen Miranda dos Santos João Paulo Ferreira Rufino Junior Ribeiro Carvalho Paulo Henrique Rocha Aride

Amazonian fishes, as an adaptive form to the annual flood cycle, develop physiological strategies to adjust to variations in their habitats. The results of this study help to understand how freshwater stingrays adapt to changes in river levels and allow us to predict the physiology of blood and water properties in situations of extreme droughts and floods in rivers. This study aimed to evaluate the physiological characteristics of the freshwater stingray Potamotrygon wallacei in response to seasonal variations in the Middle River Negro, analyzing the effects of these changes on its hematological and biochemical parameters and investigating the relationship between these changes and the physicochemical composition of the water. The animals were captured in lakes and marshes in the Mariuá Archipelago in River Negro. Five field collections were carried out during periods of different flood pulses. Blood was collected by puncture of the gill vessel after the animals were anesthetized. Hematological parameters were determined by routine methods for stingrays. Blood parameters reveal close relationships with changes in river levels, which occur throughout a hydrological cycle in the Middle River Negro region. Therefore, this indicates that the hematology of P. wallacei can be used in monitoring, indicating modifications of adverse environmental changes; however, this ecophysiological association is a complex process and needs to be further investigated.

Limnological Review doi: 10.3390/limnolrev25020016

Authors: Marina Isabela Bessa da Silva Luciana Pena Mello Brandão Ludmila Silva Brighenti Peter A. U. Staehr Cristiane Freitas de Azevedo Barros Francisco Antônio Rodrigues Barbosa José Fernandes Bezerra-Neto

The structure and density of plankton communities greatly influence carbon and nutrient cycling as well as the environmental status of lake ecosystems. This community can respond to a range of environmental drivers, including those influenced by human perturbations on local and regional scales, causing abrupt changes and imbalances. While the implications of climate and land-use changes are evident for a range of tropical lake conditions, their impacts on planktonic population dynamics are less understood. In this study, we aimed to investigate how distinctive levels of nutrients, allochthonous organic matter (OM), and sunlight availability change phytoplankton and zooplankton density and structure in a natural tropical lake. Using an in situ mesocosm facility, we manipulated the addition of nutrients and OM, in addition to sunlight availability and a combination of these treatments. We monitored limnological parameters, plankton count, and identification for 12 days. The mesocosms included eight different combinations in a 2 × 2 × 2 factorial design, each with two replicates. Inorganic nutrient addition reduced phytoplankton species richness, favoring the dominance of opportunistic species such as Chlorella sp. at much higher densities. Organic matter also increased light attenuation and caused the substitution of species and changes in dominance from Pseudanabaena catenata to Aphanocapsa elachista. On the other hand, physical shading had less influence on these communities, presenting densities similar to those found in the control mesocosms. Zooplankton presented a group dominance substitution in all mesocosms from copepod to rotifer species, and copepod growth seemed to be negatively affected by Chlorella sp. density increase. Furthermore, this community was associated with the light attenuation indices and bacterioplankton. These results indicate that tropical planktonic responses to environmental changes can effectively occur in just a few days, and the responses can be quite different depending on the nutritional source added. The punctual nutrient addition was sufficient to provide changes in this community, evidencing the strength of anthropic events associated with strong nutrient input. Understanding tropical plankton dynamics in response to environmental changes, such as those simulated in this work, is important for understanding the effects of climate and anthropogenic changes on tropical lake functioning. This knowledge can strengthen measures for the conservation of freshwater systems by allowing predictions of plankton community changes and the possible consequences for the aquatic food chain and water quality.

Limnological Review doi: 10.3390/limnolrev25020015

Authors: Balsam J. M. Al-Saadi Hussein A. M. Al-Zubaidi

Empirical equations were developed by many investigators to determine the reaeration coefficients (Ka) required for predicting dissolved oxygen concentrations (DO) in surface waters, especially rivers, lakes, and reservoirs. However, these equations yield a wide range of Ka values. In this paper, an integrated numerical-modeling-based technique was developed to check the validity of the equations before using them in water quality modeling for rivers, lakes, and reservoirs. Depending on direct field measurements at the Hilla River headwater (Saddat Al-Hindiyah Reservoir, Iraq), the temporal oxygen mass transport at the water surface was estimated numerically by solving the one-dimensional advection diffusion equation and then using each Ka empirical equation separately in the numerical model obtained the best specific-waterbody equation. The DO modeling results showed that using a reservoir reaeration coefficient of 0.1 day−1 at 20 °C predicts the best DO simulation with low MAEs of 0.4987 and 0.7880 mg/L during the study years 2021 and 2022, respectively, compared to the field data. However, using the Ka empirical equations simulates the DO with wide-ranging statistical errors even though the temporal Ka values have a similar trend during the year. It was noticed that the empirical equations produced maximum Ka values of (0.0080–0.0967 day−1) and minimum Ka values of (0.00052–0.0267 day−1) in 2021 and maximum Ka values of (0.0079 to 0.0951 day−1) and minimum Ka values of (0.00012 and 0.0231 day−1) in 2022. The present equation selection technique revealed that Broecker et al.’s equation followed by Smith’s equation, developed in 1978, are the best selection for water quality modeling at the Hilla River headwater (MAEs: 0.1347 and 0.1686 mg/L in 2021, respectively; and MAEs: 0.1400 and 0.1744 mg/L in 2022, respectively). Hence, it is necessary to find good agreement for the equation-based prediction of DO, DO source–sink, and Ka values compared to the validated model before making selection.

Limnological Review doi: 10.3390/limnolrev25020014

Authors: Maja Vurnek Renata Matoničkin Kepčija

The process of tufa deposition created the Plitvice Lakes, a unique freshwater cascade system of 16 lakes separated by tufa barriers. This complex karst hydrosystem reacts very sensitively to even small changes, and eutrophication can directly and indirectly affect tufa formation. With the purpose of determining the influence of nitrogen (N) and phosphorus (P) on periphyton’s chlorophyll a concentration, tufa deposition, and macrozoobenthos, we used nutrient-diffusing substrates. The in situ experiment combined the effects of seasons, stronger/weaker tufa deposition, and the presence/absence of macrophytes. The season was the dominant factor influencing hydrology, physicochemical factors, tufa deposition, and the effects of eutrophication. Phosphorus was the limiting factor for periphyton developing on artificial substrates, as evidenced by the highest chlorophyll a level on P and N+P substrates. Lower tufa deposition supported a higher chlorophyll a level, while macrophytes reduced the chlorophyll a concentration and tufa deposition, possibly through effects on the flow and via root respiration. The effects of nutrients on tufa deposition were not recorded. P and N+P treatment increased macrozoobenthos abundance only in some seasons. Trophic groups of macrozoobenthos responded to the addition of P and N+P in the form of higher proportions of gazers and detritivores; however, the response of macrozoobenthos was generally weaker than that of autotrophs.

Limnological Review doi: 10.3390/limnolrev25020013

Authors: Marcus Vinícius França Erika Mayumi Shimabukuro Welber Senteio Smith Mariana Morilla Ricardo Hideo Taniwaki

Tropical streams host diverse benthic macroinvertebrates, essential for ecological processes and bioindicators of ecosystem health. However, land use changes, such as sugarcane cultivation, negatively impact stream structure and function. This study examined these effects by comparing streams in sugarcane-dominated areas with those in native vegetation. Streams with native vegetation showed 2226 individuals across 107 taxa, 39 families, and 52 genera, with Chironomidae (Chironominae, Tanypodinae), Leptoceridae, Leptophlebiidae, and Calamoceratidae being the most abundant. In contrast, sugarcane streams showed 692 individuals from 47 taxa, 24 families, and 19 genera, with Chironomidae (Chironominae, Tanypodinae), Dryopidae, and Simuliidae dominating. The first hypothesis suggested that sugarcane plantations reduce taxonomic and functional diversity. The results partially confirmed this, showing lower abundance and richness in sugarcane streams, though functionality remained unchanged. The second hypothesis proposed greater seasonal taxonomic variation in sugarcane streams due to hydrological differences. Results supported this, revealing stronger seasonal shifts, particularly during the rainy season. These findings highlight the significant impact of sugarcane cultivation on aquatic ecosystems. Continuous monitoring of macroinvertebrates in agricultural landscapes is crucial for assessing environmental impacts and guiding conservation strategies.

Limnological Review doi: 10.3390/limnolrev25020012

Authors: Al Mamun

Nitrate pollution in drinking water is a major environmental and health issue. High levels of nitrates in water sources present serious risks to both the environment and public health, highlighting the need for immediate research and management efforts to reduce pollution sources and safeguard water resources for sustainable growth. This study investigates the elemental associations with nitrate concentrations in groundwater across the northeastern region of Saudi Arabia, employing diverse analytical techniques to assess water quality and develop sustainable management strategies. Spatial variations in nitrate levels were observed in both deep and shallow wells using GIS-based interpolation, revealing distinct patterns influenced by geological, hydrological, and anthropogenic factors. A strong linear correlation with a high coefficient of determination (R2 of 0.99) between electrical conductivity and dilution factor suggests the potential interchangeability of ion-selective electrode methods and conductivity meters for EC determination. The study identified a positive correlation between nitrate concentration and electrical conductivity in groundwater samples (R2 of 0.70), indicating that conductivity measurements could potentially serve as a proxy for estimating nitrate levels. However, a very weak negative correlation between nitrate and pH suggests other factors may have a more significant impact on groundwater pH. The research also highlights the strong positive correlation between nitrate and nitrate-nitrogen concentrations, reflecting their close chemical association in water. These findings contribute to the understanding of nitrate dynamics in groundwater and emphasize the importance of comprehensive water quality assessments. Future research should focus on elucidating factors influencing nitrate distribution in groundwater systems and developing more robust predictive models based on readily measurable water quality parameters.

Limnological Review doi: 10.3390/limnolrev25020011

Authors: Dmitry Karnaukhov Yana Ermolaeva Maria Maslennikova Bogdan Osadchy Sofya Biritskaya Arina Lavnikova Natalia Kulbachnaya Anastasia Solodkova Artem Guliguev Ivan Kodatenko Diana Rechile Kristina Ruban Darya Kondratieva Alexandr Bashkirtsev Alyona Slepchenko Anna Solomka Sophia Nazarova Eugene Silow

Light pollution can have a variety of effects on aquatic organisms. Despite the fact that amphipods are one of the model organisms for studying the effects of light among macroinvertebrates, data on the reaction of Baikal amphipods to artificial lighting are limited and contradictory. In this study, we examine the response of Baikal littoral and sublittoral amphipod species to artificial lighting of varying intensity and spectral composition. In the experiments, amphipods were exposed to warm and white light at three different intensity ranges (5–15, 20–35, and 80–100 lx), as well as blue and red light. As a result, it was found that the reaction of Baikal amphipods to different lighting conditions was species-specific and dependent on the spectral composition of the light more so than the intensity of the light. In particular, white LED light generally repulsed E. cyaneus, but tended to attract A. godlevskii. P. cancelloides, and G. fasciatus, suggesting that white LED light may have a greater negative impact on wildlife than warm LED light. Generally, artificial light influences the behavior of Baikal amphipods, and an increase in light pollution on Lake Baikal may lead to changes in the littoral community in certain areas of the lake subject to pollution.

Limnological Review doi: 10.3390/limnolrev25020010

Authors: John T. Lehman

Historical measurements of phosphate turnover and uptake confirm that bacterioplankton dominate phosphate dynamics at ambient steady state conditions in all but the most eutrophic samples, but phytoplankton exhibits increased control at phosphate additions as low as +10 nM. The results are consistent with the theory that uptake mechanisms of bacterioplankton become saturated as soon as phosphate concentrations are elevated above ambient levels. Uptake dynamics were consistent with multiphasic kinetics by bacterioplankton versus phytoplankton. Temperature dependence of phosphate turnover was demonstrated for Lake Superior but not for other Great Lakes in which temperatures were largely homogeneous. Ambient concentrations of orthophosphate were estimated by an inverse isotope dilution method that indicated concentrations ranged from roughly 1 to 7 nM across all the lakes surveyed.

Limnological Review doi: 10.3390/limnolrev25010009

Authors: Cortney R. Cameron Thomas J. Venning

In the absence of long-term hydrologic records, field-measured hydrologic indicators are useful for inferring past wetland hydrologic conditions, which can support research, regulation, and restoration. Inflection points on the buttresses of pondcypress trees (Taxodium ascendens) are frequently used in west-central Florida to estimate cypress wetland high water levels, known as normal pool. However, little is known about how this indicator develops. A method to estimate tree age using diameter at breast height was developed for Florida pondcypress, which can be used by forested wetland managers to constrain the maximum potential age of hydrologic indicators in groups of cypress trees. This model was applied to a waterbody with a complex history of hydrologic alterations. The waterbody had two distinct populations of buttress inflection elevations, corresponding to historic versus current water level regimes. This represents one of the first documented instances in the literature where a waterbody showed multiple buttress inflection populations in the absence of soil subsidence. This work underscores the need to consider the development timelines when interpreting the hydrologic meaning of indicator elevations.

Limnological Review doi: 10.3390/limnolrev25010008

Authors: Māra Kostanda Gunta Spriņģe Dāvis Ozoliņš Agnija Skuja Oskars Purmalis

Macroinvertebrates of the Venta River have been studied since the beginning of the 20th century. However, complex studies along the Venta River from the Latvian–Lithuanian border to its mouth into the Baltic Sea have been irregular and fragmentary. The aim of this study was to assess the ecological status of the Venta River and to analyze the abundance and fauna composition of macroinvertebrates along the entire length of the river in the territory of Latvia. This is the first study of its kind for the Venta River examining the specialization of macroinvertebrates in sediment substrates and their functional feeding groups. Within the framework of the study, the composition and functional importance of macroinvertebrates was assessed in 10 sampling sites together with the ecological quality of the river using several indices. The results show that the Venta River is dominated by benthic invertebrate collectors/gatherers, active filterers, grazers, and scrapers that have adapted to the particular type of sediments formed by silt, macrophytes, rocks, and pebbles. Different indices were calculated in order to assess the ecological quality of the Venta River. According to the saprobity index, the water quality corresponds to β-mesosaprobity, while ecological quality is mostly average; however, according to the multimetric indices, the quality of the Venta River varies from poor to high depending on the sampling station.

Limnological Review doi: 10.3390/limnolrev25010007

Authors: Renata C. H. Amancio Stella P. Pacheco Karen A. F. Moura Bianca L. Valle Julia T. C. Alves Fernanda F. Melo Vitor J. G. Silva Lívia S. Botelho Raquel T. Rocha Daiana R. Pelegrine Thiago M. Salgueiro Carlos M. O. Tadeu Vitor G. Elian Giulia A. Ducca Arielli G. Zavaski Renata L. Moreira Winnícius M. S. Sá Estevão E. O. Eller Renato B. de Oliveira-Junior Ivan M. Monteiro Lorena T. Oporto Diego G. F. Pujoni José F. Bezerra-Neto

This study investigated the impact of optically active substances on light attenuation in a tropical eutrophic urban reservoir under different seasonal conditions. Diffuse attenuation coefficients for photosynthetically active radiation (KdPAR) and ultraviolet radiation (KdUVA and KdUVB) were measured at three representative sites and correlated with water quality parameters (chlorophyll-a, total suspended solids [TSS], dissolved organic carbon, and colored dissolved organic matter [CDOM]). The results revealed significant spatial and seasonal differences, with the highest attenuation observed during the rainy season. The Ilha site exhibited the greatest coefficients (KdPAR = 6.0 m−1, KdUVA = 17.9 m−1, KdUVB = 19.0 m−1), while lower values were recorded at Barragem (KdPAR = 2.4 m−1, KdUVA = 9.1 m−1, KdUVB = 12.0 m−1) and Igrejinha (KdPAR = 3.1 m−1, KdUVA = 10.8 m−1, KdUVB = 11.9 m−1). Statistical analyses showed strong correlations between TSS and KdPAR (r = 0.66) and between CDOM and both KdUVA (r = 0.66) and KdUVB (r = 0.59), with regression models confirming TSS and CDOM as key predictors of light attenuation. These findings underscore the pivotal role of particulate and dissolved organic matter in underwater light dynamics, emphasizing the need to reduce their input during periods of heavy rainfall.

Limnological Review doi: 10.3390/limnolrev25010006

Authors: Fatima Zehrae Elhallaoui Oueldkaddour Fatima Wariaghli Hassane Brirhet Ahmed Yahyaoui Hassane Jaziri

Morocco is geographically located between two distinct climatic zones: temperate in the north and tropical in the south. This situation is the reason for the temporal and spatial variability of the Moroccan climate. In recent years, the increasing scarcity of water resources, exacerbated by climate change, has underscored the critical role of dams as essential water reservoirs. These dams serve multiple purposes, including flood management, hydropower generation, irrigation, and drinking water supply. Accurate estimation of reservoir flow rates is vital for effective water resource management, particularly in the context of climate variability. The prediction of monthly runoff time series is a key component of water resources planning and development projects. In this study, we employ Machine Learning (ML) techniques—specifically, Random Forest (RF), Support Vector Regression (SVR), and XGBoost—to predict monthly river flows in the Bouregreg basin, using data collected from the Sidi Mohamed Ben Abdellah (SMBA) Dam between 2010 and 2020. The primary objective of this paper is to comparatively evaluate the applicability of these three ML models for flow forecasting in the Bouregreg River. The models’ performance was assessed using three key criteria: the correlation coefficient (R2), Akaike Information Criterion (AIC), and Bayesian Information Criterion (BIC). The results demonstrate that the SVR model outperformed the RF and XGBoost models, achieving high accuracy in flow prediction. These findings are highly encouraging and highlight the potential of machine learning approaches for hydrological forecasting in semi-arid regions. Notably, the models used in this study are less data-intensive compared to traditional methods, addressing a significant challenge in hydrological modeling. This research opens new avenues for the application of ML techniques in water resource management and suggests that these methods could be generalized to other basins in Morocco, promoting efficient, effective, and integrated water resource management strategies.

Limnological Review doi: 10.3390/limnolrev25010005

Authors: Dagne Tafa Dibar Kun Zhang Zhongze Zhou

Macrophytes taxa composition determines microinvertebrates utilized as environmental indicators in freshwater ecosystems. This study was conducted in Shengjin Lake. In this lake, local communities have been practicing using sine fishing nets for fishing and this has a disrupting effect on macrophyte vegetation, even though it was the major for the disappearance of submerged vegetation before it was banned. As a result of this sine fishing net ban by the local authorities, the vegetation that had disappeared began to recover. Thus, this study investigated the role of architecturally differentiated macrophytes restoration effect on zooplankton communities’ diversity, abundance, and species composition; open water was used as a control. For this, the data were collected from different habitats via site 1 (open water) site 2, (free-floating), site 3 (emergent and submerged), site 4 (submerged), and site 5 (emergent) macrophytes. In the present study, the results demonstrated that the relative mean density of Rotifer was measured high which ranged from (219 ± 141–678 ± 401 ind L−1), mainly dominated by Keratella cochlearis and Lecane cornuta species. Following Rotifera, Cladocera population density was reported high and ranged within (36 ± 6.2–262.5 ± 49.4 ind L−1). The Cladocera group was dominated by Daphnia spp., Moina micura, Ceriodaphnia reticulata, and Chydorus latus species. Compared to Rotifer and Cladocera, Copepod community were recoded least with relative mean density ranged within (11.52 ± 2.22–85.5 ± 27 ind L−1) and dominated by Microcyclops javanus, Thermodiaptomus galebi, and Sinocalanus doerrii species. From environmental variables and the zooplankton density relationship analyzed, the redundancy analysis (RDA) results indicated that Water Temperature, Chlorophyll a, Dissolved Oxygen, Total Phosphorus, and Ammonium Nitrogen were found the most influential variables on zooplankton communities. Stepwise regression correlation showed that Copepod and Cladocera were found more dependent on environmental factors. For instance, Nitrate Nitrogen was negatively correlated with Cladocera, Copepod, and total zooplankton biomass but positively with Cladocera diversity. Water Temperature showed a positive relationship with Rotifer diversity; however, both Chlorophyll a and Electrical Conductivity were correlated positively with Cladocera biomass. Species diversity by the Shannon–Wiener index (H) illustrated a dynamic trend among the monitored sites which ranged between (0.65–4.25). From the three groups of zooplankton communities in contrast to Cladocera and Copepod, Rotifer species obtained more diversity across the studied sites. The Cladocera diversity (H′) index indicated a similar tendency in all sites. However, more Copepod diversity (H′) was observed in site 4. In conclusion, this study results can provide valuable insights into the health and dynamics of the aquatic ecosystem to understand factors deriving ecological imbalance and develop an integrated approach for effective strategies for management and conservation.

Limnological Review doi: 10.3390/limnolrev25010004

Authors: Xizhe Wang Kengo Kurata

Estuarine lakes possess significant ecological value. Their complex hydrological environments give rise to diverse habitats, providing a home to numerous life forms. However, with the intensification of the impacts of global climate change, the estuarine lake ecosystem is facing severe challenges. Through trend analysis and differential analysis, this paper elaborates on the changes in nitrogen and phosphorus nutrients in the bottom water of Lake Nakaumi from 2013 to 2017. It analyzes the differences between the El Niño period and the non-El Niño period, speculates on the possible connections between the changes in nutrient load and the El Niño phenomenon, and uses the traditional water quality assessment method of the WQI to more intuitively demonstrate the fluctuations in nutrient load. Based on the analysis of the case of Lake Nakaumi, possible environmental management suggestions are put forward. Additionally, the paper compares and discusses the differences in the changes of lakes at adjacent latitudes during similar periods. As for the bottom water of Lake Nakaumi, there may be the following connections between the changes in its nutrient load and the El Niño phenomenon: (1) DPO4-P was most sensitive to the peak intensity of the El Niño phenomenon. (2) Compared with NO3-N, the changes in NO2-N and DPO4-P were more sensitive to the start of the El Niño cycle. (3) The El Niño phenomenon had differential impacts on various forms of nitrogen and phosphorus in Lake Nakaumi. The focus of this paper is to explore the connection between the El Niño phenomenon and the changes in the nutrient load of the bottom water of estuarine lakes and to find a method beneficial to environmental management. However, due to the limitations of the currently available data, there are still many deficiencies that need to be further addressed. It is hoped that this paper can attract the attention of relevant researchers to this issue.