Limnological Review doi: 10.3390/limnolrev26020020

Authors: Rubén Hernández-Morales Isabel Israde Alcantara Nicolás Waldmann Gabriela Ana 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 (medianln(RR)ln(RR) = −1.89), whereas Mn removal is more variable and less efficient (medianln(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.

Limnological Review doi: 10.3390/limnolrev25010003

Authors: Ying Zhang Keren Zhang Zixuan Zhang

Hainan Island has rich water resources and unique lake ecosystems. Organically connecting lakes and wetlands with forest ecosystems should be considered in order to strengthen biodiversity protection, form a continuous green corridor to promote species migration and gene exchange, and enhance the stability and resilience of the overall ecological system and maximize its benefits. The method of linear programming was used in this study to analyze the forest ecosystem on Hainan Island in China in order to provide a scientific basis for the integration, protection and management of lakes, wetlands and forests. This study points out that the ratio of the area of timber forest, protection forest, special-purpose forest and bamboo forest should be adjusted from the current 68:22.9:7.1:1.8 to 24:72.8:2.5:0.6. The average shadow price of the reasonable use of different forest lands on Hainan Island is 2512.46 CNY/ha and the optimal value of special-purpose forest is 4376.04 CNY/ha, rather than the current 6888.50 CNY/ha. This study also shows that the timber forest, special-purpose forest and bamboo forest on Hainan Island are short-term products, while protection forest, wood-fuel forest, economic forest, open forest land, shrub land, young afforested land and non-forest land are long-term products, for which it is not easy to obtain benefits in the short-term. A combination of long- and short-term forest ecological planning should be considered to maintain the various long-term benefits. This study finally proposes that Hainan Island should reduce its proportion of timber forest area; increase its proportion of protection forest area; focus on the integrated development of lakes, wetlands and forests and biodiversity conservation goals; and pay close attention to the adjustment of forest type structure in order to meet the needs of ecological province construction and sustainable development.

Limnological Review doi: 10.3390/limnolrev25010002

Authors: Hui Liu Xiangqun Wu Xu Chen

Diatoms have been widely used for aquatic environment assessment. However, the progress of diatom research is uneven in different regions of the world. This study gathered both Chinese and English articles on diatom research in the Yangtze River Basin in order to explore recent progress in this field. Using the Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases, we gathered 419 articles (1995–2024) on diatom research in the Yangtze River Basin. There is a substantial increase in the number of articles since 2000. Since the mid-1990s, a total of 63 new diatom species have been identified in this region. Based on limnological investigations of lakes in the Yangtze River Basin, diatom-based conductivity and total phosphorus (TP) transfer functions have been developed for quantitative reconstruction of past conductivity and TP in the water column. The results revealed a recent shift in thematic focus from eutrophication to biodiversity dynamics, the ecosystem regime shift, and ecohydrological change. Although diatom research in the Yangtze River Basin has achieved fruitful outputs, further studies are urgently needed to explore diatom biodiversity and the ecological status of aquatic ecosystems in this rapidly-developing region. The results can improve our understanding of diatom research progress and hence provide important clues for further studies.

Limnological Review doi: 10.3390/limnolrev25010001

Authors: Abraham Addo-Bediako

Chemical pollution in freshwater ecosystems poses a significant environmental threat, often hindering access to safe drinking water for human populations. The Olifants River Basin in South Africa is particularly vulnerable due to escalating mining and agricultural activities, and domestic waste discharged into the rivers. In this study, the risk posed to humans by exposure to potentially toxic elements (PTEs) in water from two rivers, the Blyde and Steelpoort, was assessed. Water samples were collected from upstream, midstream, and downstream locations of these rivers, and the concentrations of eight PTEs (Arsenic, Cadmium, Chromium, Iron, Manganese, Nickel, Lead, and Zinc) were determined using inductively coupled plasma-optical emission spectrophotometry. Furthermore, two pathways of exposure, direct ingestion and dermal absorption, were used to evaluate their potential impacts on human health. The findings indicate that direct ingestion poses a greater risk to human health compared to dermal absorption. While PTEs may pose little non-carcinogenic risk for adults, higher risk was observed in children. This is an indication that children are at higher risk using water from the rivers, sometimes without any form of treatment. When carcinogenic risks (CRs) were computed for both adults and children for As, Cr, Ni, and Pb levels, the CR values were above the threshold limit, except for Pb, indicating a potential carcinogenic risk. This study underscores the need for regular monitoring of chemical pollution, and the implementation of effective mitigation strategies to safeguard both river ecosystems and human health, including proper treatment of water for domestic and agricultural purposes.

Limnological Review doi: 10.3390/limnolrev24040038

Authors: Mohamed A. Ashour Mohamed Khairy Ali Tawab E. Aly

As spillways are hydraulic structures constructed for the safe release of floodwater from the upstream (US) side of a dam to the downstream side, or from the end of canals and drains to a lower stream, the upstream water flow of such structures gains significant amounts of potential energy. As this water flows over a spillway or escapes, the gained potential energy is converted into kinetic energy, resulting in the water gaining an increasing velocity, thereby enhancing the flow’s destructive potential. This can have a harmful impact on the hydraulic performance and the structural stability of the spillway itself. To avoid such harmful effects, engineers and designers of such structures usually provide the spillways and water escapes with some tools for dissipating that kinetic energy and decreasing the flowing water’s velocity. The present study aims to enhance the performance efficiency of such dissipating tools, as well as to improve the quality of the flowing water by leveraging the significant turbulence generated by the existing energy dissipators on the back of the spillway body. The aeration process enabled by this turbulence increases the dissolved oxygen contents, thereby enhancing the water quality, which is one of the main objectives of this work. On the back surface of the spillway, various dissipater shapes with different geometrical configurations, dimensions, and combinations were tested, in order to determine the most suitable engineering treatments for maximizing the dissolved oxygen content and improving the water quality for various uses, as the study’s main goal. By testing 21 different model configurations with the available laboratory discharges, the study successfully identified the most effective shape and properties of the desired dissipator, which increased the dissolved oxygen content by an average of 21.70% and dissipated water energy by about 69%.

Limnological Review doi: 10.3390/limnolrev24040037

Authors: Anelise Rodrigues Machado Garcia Diego Guimarães Florencio Pujoni José Fernandes Bezerra-Neto

The 2015 Fundão tailings dam collapse in Mariana, Brazil, was a major environmental catastrophe. Assessing its long-term effects on water quality is critical for environmental restoration and policy development. In this study, we reconstructed a 15-year time series of five water quality parameters to assess whether the collapse caused permanent changes. Using public data from the Minas Gerais Water Institute (IGAM), we fitted generalized additive models for location, scale, and shape to model long-term trends in turbidity, total solids, conductivity, pH, and dissolved oxygen. Predictor variables included daily precipitation and smooth functions for time and longitudinal distance along the river. As expected, turbidity and total solids increased sharply after the collapse; however, the mean values returned to pre-collapse levels within four years. Conductivity, which was already elevated pre-collapse, remained high following the passage of the tailings plume. Although we observed a tendency toward pre-collapse values, the long-term conductivity mean did not fully stabilize to previous levels. No clear patterns were observed for pH or dissolved oxygen. This study highlights the acute impact of the dam collapse on five water quality parameters in the Doce River and illustrates the river’s subsequent stabilization process, although other important and chronic impacts are still persistent. Long-term studies such as this provide valuable insights into the dynamics of fluvial systems.

Limnological Review doi: 10.3390/limnolrev24040036

Authors: Isabel Navarro Law Isabelle Durance Rachel Benstead Michael E. Fryer Colin D. Brown

Currently, reviews focusing on the distribution of macrophytes focus primarily on large water bodies, regardless of the fact that small water bodies (SWBs), such as ponds, ditches and streams, often support higher levels of gamma macrophyte richness. This review investigates the direction and strength of the relationship between 13 abiotic factors and macrophyte distribution in SWBs. Results demonstrate that there are distinct differences between the effects of abiotic factors on bryophytes and those on vascular macrophytes of different morphological forms. Whilst shading and velocity have a significant (p < 0.05) negative relationship with vascular macrophyte richness and a positive relationship with bryophyte richness, the reverse is true for the size of a water body, depth and concentration of nitrogen. Vascular macrophyte richness has a significant (p < 0.05) negative relationship with distance to a stream source, isolation, the proportion of surrounding land that is woodland, total phosphorus concentrations and pH. The strength of the influence of substrate size and water body size differs between vascular macrophyte morphologies. Key knowledge gaps include bryophyte distribution and the effect of hydroperiod and surrounding land use on macrophyte communities. In order to conserve all macrophyte morphologies and taxa, it is important to protect SWBs with a diverse set of conditions.

Limnological Review doi: 10.3390/limnolrev24040035

Authors: Artem Lapenkov Alina Guzeva Ksenia Zaripova Dina Dudakova Artem Trifonov

This study investigates the seasonal dynamics and interrelationships between geochemical and hydrobiological parameters in lake ecosystems impacted by fish cage farming in Lake Ladoga, Russia. Environmental conditions at three trout farms were assessed, focusing on water and sediment quality as well as benthic and zooplankton communities. For each farm, two categories of sampling sites were designated: cage sites and reference sites located 100–600 m away from the cages. Fieldwork was carried out across four seasons in 2023: February, June, August, and November. The findings indicate that intensive fish feeding results in significant organic waste accumulation beneath trout cages, altering the composition and abundance of planktonic and benthic organisms. The organic matter content in sediments beneath the cages during periods of intensive feeding was found to increase 2–5 times compared to the reference sites. In winter, accumulated organic matter in the sediments underwent mineralization, bringing hydrobiological indicators closer to the reference values. The geochemical and hydrobiological parameters analyzed in this study serve as valuable indicators for developing ecological monitoring approaches in freshwater cage aquaculture.

Limnological Review doi: 10.3390/limnolrev24040034

Authors: José Luis Carballo José Antonio Cruz-Barraza José Carlos García-Gómez

Alien species constitute one of the main threats to freshwater ecosystems, negatively impacting biodiversity, economy, and ecosystem services. Here, we use morphological and genetic data to show the presence of a new alien freshwater sponge in Europe, Rosulaspongilla rhadinaea, a Ponto-Caspian species which recently has been found in the fluvial port of Seville (Guadalquivir River, Spain). We also reviewed the mechanisms and adaptations of freshwater sponges for dispersal. The gemmule is the key structure for understanding their life history, evolution, and dispersal capacity, since their high salinity tolerance may have made possible the spreading of these sponges on the hulls of ocean-going ships that frequent freshwater ports. Once established, they are dispersed via river currents and intraregional boat traffic through the network of interconnected channels, which act as invasion corridors. Transport via phoresy attached to mobile animal vectors such as birds (especially migrating birds) has also been demonstrated in several sponge species. Gemmules may be attached on the feathers and scales, or even to be transported in the guts of these animals, followed by defecation of viable gemmules. Transport associated with other invasive freshwater species, such as mussels, cannot be ruled out. The scarcity of taxonomic studies of freshwater sponges in the Iberian Peninsula might explain why the species had not been recorded.

Limnological Review doi: 10.3390/limnolrev24040033

Authors: Harith K. Buniya Nuha A. Mohammed Dhyauldeen Aftan Al-Hayani

Antibiotic resistance in cyanobacteria represents a global threat to public health. The widespread presence of cyanobacteria in aquatic environments exposes them to antibiotic contamination. Cyanobacteria are also in direct contact with pathogenic bacteria containing antibiotic-resistance genes (ARGs), which impart these characteristics to them. This study aims to examine the presence of some ARGs in locally isolated cyanobacteria species, Spirulina laxa, Chroococcus minutes, Oscillatoria princeps, Oscillatoria proteus, Oscillatoria terebriformis, and Lyngbya epiphytica, and compare the presence of these genes in two pathogenic bacteria, Escherichia coli and Klebsiella pneumoniae. Ampicillin (Ap) and erythromycin (Em) resistance genes were detected in five algal samples. Meanwhile, Chloramphenicol (Cm) and gentamicin (Gm) resistance genes were apparent in only two species. Genes encoding resistance towards kanamycin (Km) and spectinomycin (Sp) were recorded in three specimens. It was also found that E. coli possessed resistance genes for four antibiotics, ampicillin (Ap), erythromycin (Em), gentamicin (Gm), and kanamycin (Km), whereas K. pneumoniae was resistant towards three antibiotics, ampicillin (Ap), gentamicin (Gm), and kanamycin (Km). The results show that there is a match in antibiotic-resistance genes in both cyanobacteria and pathogenic bacteria. Suggesting the possibility that cyanobacteria could acquire ARGs from the environment through horizontal gene transfer. Thus, freshwater cyanobacteria may play a significant role in the prevalence of ARGs in their environment.

Limnological Review doi: 10.3390/limnolrev24040032

Authors: Flávio H. B. Souza Mariana Morilla Beatriz Guedes-Pereira Kauê Lemes Ricardo H. Taniwaki

Water quality in urban streams often reflects the broader environmental challenges posed by dense population centers, where pollution from untreated sewage and runoff can significantly degrade ecosystems. This study examines the spatial and temporal variations of carbon, nitrogen, and phosphorus concentrations in the Tamanduateí River, which runs through the Metropolitan Region of São Paulo, Brazil. Data were sourced from the annual reports of the Environmental Company of the State of São Paulo (CETESB) covering the period from 2011 to 2022. Between 2011 and 2017, carbon and phosphorus concentrations declined, likely due to sanitation improvements. However, since 2017, these concentrations have been rising again, indicating renewed pollution inputs, primarily from untreated sewage. Nitrogen levels remained consistently high, with elevated concentrations observed upstream, linked especially to domestic effluent discharges. The recent increase in phosphorus levels is also of concern. The absence of spatial variation in phosphorus suggests diffuse pollution from urban areas, while nitrogen decreases downstream, possibly due to biological assimilation. The study underscores the pressing need for enhanced sewage management. Drawing from the successful revitalization of the Cheonggyecheon stream in Seoul, implementing nature-based solutions and regular maintenance could effectively reduce nutrient pollution and improve water quality, facilitating the restoration of the Tamanduateí River.

Limnological Review doi: 10.3390/limnolrev24040031

Authors: María Concepción Martínez-Rodríguez Diego Domínguez-Solís Lorena Elizabeth Campos-Villegas Zurizaday García-Sánchez Miguel Alvarado-Cardona

Ecological flow refers to the minimum amount of water that must be maintained in a body of water to protect and preserve aquatic ecosystems. This article aims to analyze the function of ecological flow to address the reproduction of the natural hydrological regime of the San Rodrigo River, Coahuila, Mexico. A quantitative methodology was used where the ecological flow was determined based on the Mexican Standard NMX-AA-159-SCFI-2012 considering the period from 1962 to 2016. The maximum data allows us to identify runoffs of low magnitude of 6.65–15.60, those with an average trend close to 500 Mm3, and floods of extraordinary volume (namely, those 844–1260 and 1670 Mm3) with a frequency of every 35 years. Likewise, the river marks drastic changes in the flow in certain years, ranging from 0.64 to 1260 Mm3, so that the rate of variation would possibly exceed several orders of magnitude scaled in an annual phase. In conclusion, this calculation indicates that the body of water may have the function of environmental conservation covered throughout the year, with the data suggesting that in the short term the river will recover part of the water that passed through its course and thus avoid its deterioration.

Limnological Review doi: 10.3390/limnolrev24040030

Authors: Otman El Mountassir Mohammed Bahir Samir Hakimi Turki kh. Faraj Paula M. Carreira

The hydrogeochemical properties and evolution of groundwater in the Essaouira syncline basin in northwestern Morocco were investigated in this study, with a total of 447 samples during different campaigns (April 2017, May 2018, March 2019, and July 2020). These samples were analyzed for major ions and stable and radioactive water isotopes (δ2H, δ18O, and 3H). With decreasing rainfall from climate change in Morocco, it is crucial to assess the sustainability of groundwater reserves. This shortage leads to the degradation of water and soil quality. To ensure sustainable water management and preserve the environment in the study area, it is necessary to assess groundwater quality for drinking and irrigation, take precautions, and establish management plans. This study assessed groundwater quality using two water quality index methods (WQI and IWQI). Several natural processes control groundwater mineralization, including the dissolution of evaporite and carbonate minerals, cation exchange phenomena, evaporation, and seawater intrusion. According to the results obtained using the WQI method, all groundwater samples in the study area are generally of poor quality and must be treated before being used for domestic purposes. Based on the results obtained by the IWQI method, the samples are suitable for use as irrigation water, especially for plants resistant to high salinity concentrations. Stable isotope measurements (δ2H and δ18O) indicate that Atlantic precipitation continuously recharges the recharge areas of the Essaouira Basin. Thus, the low values of tritium (3H) in groundwater mean that the freshwater in the Essaouira Basin is ancient.

Limnological Review doi: 10.3390/limnolrev24040029

Authors: John T. Lehman Shelby Burgess

Historical plankton samples from the St. Lawrence Great Lakes were subjected to taxon-specific 15N analysis to test the hypothesis that the changes recorded in zooplankton communities during the 21st Century are related to changes in the trophic positions of large-bodied carnivorous copepods. Daphnia mendotae was used as the reference herbivore for trophic-level comparisons. The results were that Limnocalanus macrurus, Diaptomus (Leptodiaptomus) sicilis as well as the cladoceran Bythotrephes cederstroemi show evidence of elevated carnivory compared to data from the 20th Century. The large diaptomid Diaptomus (Leptodiaptomus) sicilis has a stable isotope signature that is significantly more carnivorous in Lake Superior than in Lakes Michigan and Huron by approximately one-half trophic level. Differences were found in 10 cases out of 15 for Limnocalanus (Huron, Michigan Superior), 6 cases out of 15 for Diaptomus (Huron, Michigan) and in 1 out of 1 for Senecella (Superior). We did not find evidence to support the theory that large-bodied calanoid copepods may have improved their representation in the food webs of the upper Great Lakes by shifting their trophic position downward. Instead, large-bodied Calanoida have increased their trophic positions in parallel with their increased relative abundance. More research is thus needed to explain the driving forces for changing food web dynamics in the Great Lakes.

Limnological Review doi: 10.3390/limnolrev24040028

Authors: Elena Gogina Nikolay Makisha Igor Gulshin Anna Reshetova

This article presents the results of a two-stage study: the first stage involved assessing the dependence of the increase or decrease in the concentration of volatile fatty acids (VFAs) on external factors and then assessing the relationship between the VFA concentration in the supernatant after fermentation and the processing characteristics (temperature, mixing mode, alkalinity, pH, nitrogen and phosphorus content). The greatest increase in VFAs (content up to 285 mg/L in the supernatant) was achieved at a temperature in the range of 28 to 38 °C with constant mixing of the sludge. Based on the results of the second stage, a conclusion was made on the efficiency of using a particular substrate depending on the concentration of phosphorus phosphates in the incoming wastewater. The study results showed that 7.54 mg/L of phosphorus can be removed with a given probability (for activated sludge, raw sludge and wastewater). It is recommended to compensate for the excess of this concentration by dosing the acetic acid solution at a rate of 3800 meq/L of VFA per 1 mg/L of phosphorus phosphates. The literature does not contain any results of parallel studies of the operation of a controlled bioreactor with artificial external feeding and acidified VFA. The results of the study can be applied in planning sludge acidification systems in the technological scheme of wastewater treatment and sludge processing.

Limnological Review doi: 10.3390/limnolrev24040027

Authors: Daniel Henrique Carneiro Salim Gabriela Rabelo Andrade Alexandre Flávio Assunção Pedro Henrique de Menezes Cosme Gabriel Pereira Camila C. Amorim

This study investigates the impact of environmental conditions on reflectance values obtained from multispectral Unmanned Aerial System (UAS) imagery in inland waters, focusing on sun glint, cloud glint, wind-generated waves, and cloud shading projections. Conducted in two reservoirs with differing water qualities, UAS platforms equipped with MicaSense Altum and DJI Phantom 4 Multispectral sensors were used to collect multispectral images. The results show that sun glint significantly increases reflectance variability as solar elevation rises, particularly beyond 54°, compromising data quality. Optimal flight operations should occur within a solar elevation angle range of 25° to 47° to minimize these effects. Cloud shading introduces complex variability, reducing median reflectance. Wind-generated waves enhance sun glint, increasing variability across all spectral bands, while cloud glints amplify reflectance non-uniformly, leading to inconsistent data variability. These findings underscore the need for precise correction techniques and strategic UAS deployment to mitigate environmental interferences. This study offers valuable insights for improving UAS-based monitoring and guiding future research in diverse aquatic environments.

Limnological Review doi: 10.3390/limnolrev24040026

Authors: Mohamed El Amrani Khadija Diani Mohamed Hafedh Hamza Mohamed Elhag Said Courba Afaf Amine Moulay Ahmed Ben Driss Lahcen Ousaid Nabil Mdiker Youssef Hahou Larbi Boudad

Understanding paleo-ice flow chronology is essential for reconstructing past ice mass dynamics, interpreting the current landscape, and identifying the sources of Quaternary sediments in deglaciated regions. A recent systematic mapping of striated bedrock and streamlined landforms south of Lake Mistassini in Canada reveals a complex sequence of five ice flows. The earliest flow was directed to the southeast (SE) and originated from a NE-SW ice divide located northwest of Lake Mistassini at the Last Glacial Maximum. A progressive clockwise rotation of this ice divide, likely triggered during the early deglaciation, appears to have generated ice flows toward the south–southeast (SSE) and then toward the south (S). During the later stages of deglaciation, the flow originated from the Québec–Labrador Dome, initially toward the south–southwest (SSW) and then toward the southwest (SW). This study presents new data on ice flows south of Lake Mistassini and shows that the southward and south–southeastward ice events occurred before the late stage of deglaciation. This interpretation contradicts some previous studies and will contribute to the discussion on the dynamics of the Laurentide Ice Sheet in the Mistassini area and support mineral exploration efforts in the region.

Limnological Review doi: 10.3390/limnolrev24040025

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

The impacts of hydropower plants and their reservoirs on floodplains can potentially create new environmental filters and reduce the exchange of organisms and access to habitats. In this study, we aimed to compare the fish assemblage associated with aquatic macrophytes between floodplain lakes under natural conditions and a regulated floodplain lake in the Environmental Protection Area of Rio Pandeiros, Brazil. We tested the hypothesis that in the regulated floodplain lake, there would be a lower richness and a greater of abundance of macrophytes and fish than is natural. We also verified the influence of the seasons, macrophyte bank richness, and biomass on the fish assemblage abundance. The fish assemblages differed between the regulated and natural floodplains due to the higher richness and abundance of fish in the natural floodplains. The presence of non-native and generalist species in the regulated floodplain influenced the dissimilarity between the floodplains. Migratory species have been found only in natural floodplains. Fish abundance was negatively related to macrophyte richness on the regulated lake. There was a lower fish abundance and macrophyte richness in the regulated lake. There was no evidence that macrophyte biomass affected the abundance and richness of fishes. Our results confirm that the Pandeiros small hydroelectric dam affects the fishes’ assemblage and the macrophyte community, since the regulated floodplain lake has a lower richness and abundance of fish. The regulated floodplain lake is connected to a reservoir created by a small hydroelectric dam, which will be removed in the coming years. The removal of this dam might change these dynamics, and this must be evaluated when the change is implemented.

Limnological Review doi: 10.3390/limnolrev24040024

Authors: Halina Falfushynska Kamila Lewicka Piotr Rychter

Water pollution is a pressing global issue significantly affecting ecosystem health, biodiversity, and human well-being. While numerous studies have concentrated on toxic metals like cadmium, lead, and mercury, essential metals such as copper and zinc often receive less attention. This review focuses on the distribution and occurrence of copper and zinc in surface water, their accumulation in freshwater organisms, and potential strategies for mitigating the environmental pressure caused by these metals. Zinc concentrations in uncontaminated freshwater usually range from 3 to 12 μg∙L−1 and form low-bioavailable hydroxo-complexes that are especially stable in weak alkaline water. The zinc concentration trend globally is Europe > Africa > Asia > South America > North America. Conversely, copper concentrations vary from 0.2 to 5.5 µg∙L−1, with the order being Asia > Africa > South America > North America > Europe. Humic substances are the likely predominant ligands for copper in these environments. The accumulation of copper and especially zinc in freshwater animals may not be a reliable indicator of metal pollution due to potential metabolic regulation. Bioremediation approaches, including phytoremediation and biosorption using plants and microorganisms, show promise in addressing water contamination. Future research should emphasize advanced bioremediation methods, emission reduction strategies, and refined modeling techniques to predict pollution trends and evaluate remediation effectiveness.

Limnological Review doi: 10.3390/limnolrev24030023

Authors: Ivan Kirvel Vitalii Martyniuk Ivan Kovalchuk Ion Andronache Vasyl Korbutiak Ivan Zubkovych

The cartographic landscape analysis of Lake Doshne employs geographic landscape methods, GIS cartographic modeling, and geo-ecological analysis. This study includes hydrochemical analysis of the lake’s water mass, focusing on saline blocks, tropho-saprobiological indicators, and specific toxic action indicators. Three geological sections of anthropogenic and pre-Quaternary complexes, along with a geological–lithological transverse profile of the lake basin, were developed. Additionally, a geographical landscape model of the lake’s natural aquatic complex was presented, distinguishing littoral–sublittoral and profundal aquatic sub-tracts and five types of aquafacies with landscape metric assessments. This approach enables a comprehensive analysis and the creation of cartographic models that can serve as a basis for lake cadastre and optimization of the ecological and landscape conditions in local territories.

Limnological Review doi: 10.3390/limnolrev24030022

Authors: Athina Ziou Alexandra S. Douligeri Nikolaos Kiriazis Athanasios Korakis Nikolaos Petsis Dimitrios K. Moutopoulos George Katselis

The impoundment of Aoos springs was created in 1990 to facilitate hydroelectric production, and fish fauna has been enriched through the years due to deliberate or accidental fish stockings, with certain invasive alien fish species arising (i.e., Lepomis gibbosus, Carassius gibelio), some of which are ranked among the most dangerous species for global biodiversity. A three-year monitoring survey was conducting to map the nesting areas of Pumpkinseed, L. gibbosus, to assess the effectiveness of electrofishing as an active method to reduce the spread of the corresponding species and to identify the impact of the L. gibbosus on native species. The largest percentage of nests was found in areas with silty-sand bottoms (53.4%) and low vegetation. The potential nesting area was estimated at 1.97 km2 and the area of confirmed nesting was 0.33 km2. The species appeared to nest in a small area, compared to the potential nesting area. The results also indicate that a significant percentage of the target species (71.6% of the total number of species) was removed, with an average time per sampling of 1.2 ± 1 h, whereas the impact on the other native species was minimal. These results are important for designing and implementing programs for the eradication or reduction of L. gibbosus in the impoundment of Aoos springs.

Limnological Review doi: 10.3390/limnolrev24030021

Authors: Tasneem I. M. Abdelmagid Isam Abdel-Magid Eltayeb H. Onsa Elsadig Ghassan M. T. Abdalla Hisham I. M. Abdel-Magid Abderrahim Lakhouit Wael S. Al-Rashed Ahmed Hassan A. Yaseen Gasim Hayder

Municipal management involves making decisions on various technical issues, and one such crucial aspect is the multicriteria decision-making process. When choosing suitable locations for wastewater treatment plants, it becomes necessary to consider a range of factors such as technical feasibility, economic viability, environmental impact, ecological aspects, and management requirements. However, evaluating these criteria and dealing with uncertainties can be complex. To address this challenge in the Tabuk region, a combination of two powerful analytical methods, the fuzzy analytical hierarchy process (FAHP) and geographical information system (GIS), were employed. The FAHP methodology allows for considering uncertainties and subjective judgements, while GIS provides spatial analysis capabilities. By combining FAHP and GIS, a thorough evaluation of potential wastewater treatment plant locations was conducted by determining the relative weights for each geospatial parameter. These weights were then used to generate a suitability map, visually representing the most favourable areas for site selection. The FAHP analysis resulted in higher importance given to the treatment plant’s distance to urban areas, followed by the distance to roads among the seven investigated parameters. The integrated FAHP-GIS model results show that the western parts of the region are most suitable for constructing wastewater treatment plants. These findings are valuable in facilitating multicriteria decision-making for identifying the optimum site in the area. In summary, integrating FAHP and GIS in the assessment process enables decision-makers to consider various technical, economic, environmental, ecological, and management aspects, thereby providing a comprehensive framework for site selection that can be replicated in other regions with different conditions. This approach enhances the decision-making process in municipal management and promotes more informed and effective planning in the Tabuk region.

Limnological Review doi: 10.3390/limnolrev24030020

Authors: Devleena Sahoo Ngoc Khanh Ni Tran Thi Gia-Hang Nguyen Thi Thu Hoai Ho Thi Thuy Hang Phan Duong Thu Huong Hoang Ngo Huu Binh Thi Thu Lien Nguyen Luong Quang Doc Noureddine Bouaïcha Tri Nguyen-Quang

The Tam Giang-Cau Hai lagoon (TGCH) in Thua Thien Hue province (Vietnam) is a marsh/lagoon system and ranks among the largest waterbodies in Southeast Asia. It plays a significant role in terms of both socio-economic and environmental resources. However, anthropogenic stress, as well as the discharge of untreated domestic and industrial sewage with agricultural runoff from its three major tributaries, dramatically damages the water quality of the lagoon. Especially after heavy rain and flash floods, the continuous degradation of its water quality, followed by harmful algal and cyanobacterial bloom patterns (HABs), is more perceptible. In this study, several physicochemical factors, cyanotoxins (anatoxins (ATXs), saxitoxins (STXs), microcystins (MCs)), phycotoxins (STXs, okadaic acid (OA), and dinophysistoxins (DTXs)) were analyzed in water and shellfish samples from 13 stations in June 2023 from 13 stations, using enzyme-linked immunosorbent assay (ELISA) kits for the ATXs and STXs, and the serine/threonine phosphatase type 2A (PP2A) inhibition assay kit for the MCs, OA, and DTXs. The results showed for the first time the co-occurrence of freshwater cyanotoxins and marine phycotoxins in water and shellfish samples in this lagoon. Traces of ATXs and STXs were detected in the shellfish and the orders of magnitude were below the seafood safety action levels. However, toxins inhibiting the PP2A enzyme, such as MCs and nodularin (NODs), as well as OA and DTXs, were detected at higher concentrations (maximum: 130.4 μg equiv. MC-LR/kg shellfish meat wet weight), approaching the actionable level proposed for this class of toxin in shellfish (160 μg of OA equivalent per kg of edible bivalve mollusk meat). It is very important to note that due to the possible false positives produced by the ELISA test in complex matrices such as a crude shellfish extract, this preliminary and pilot research will be repeated with a more sophisticated method, such as liquid chromatography coupled with mass spectroscopy (LC-MS), in the upcoming research plan.

Limnological Review doi: 10.3390/limnolrev24030019

Authors: Marcela Cunha Monteiro Luci Cajueiro Carneiro Perreira Rauquírio Marinho da Costa

In recent years, climate events such as Drought, El Niño, and La Niña have become increasingly frequent and more intense. Oceanographic monitoring was used to collect hydrological data in the middle and lower sectors of the Caeté estuary in different years. Negative rainfall anomalies of up to 45% were recorded during periods marked by drought and El Niño events, which make the water in the Caeté estuary more saline and alkaline. During these events, the retention of dissolved inorganic nutrients in the middle sector appears to support increased eutrophication and more productive waters, whereas moderate eutrophication and lower productivity were observed in the lower sector. During La Niña events, by contrast, positive rainfall anomalies may reach 60%, resulting in more oxygenated water in the estuary. In addition, the lower sector tends to be more eutrophic during periods of high rainfall and freshwater discharge, as observed in this study during a La Niña event. The paucity of data on the effects of extreme climate events in Amazonian environments means that the findings of the present study may provide a useful model for the assessment of the effects of these events on other natural environments in the Amazon region.

Limnological Review doi: 10.3390/limnolrev24030018

Authors: Santiago Andrés Echaniz Alicia María Vignatti Gabriela Cecilia Cabrera

Many saline lakes are temporary, with large variations in salinity, and their biota is adapted to withstand unfavorable periods. Utracan Lake, in a protected area in central Argentina, was studied on three occasions under different environmental conditions. In 2007, depth and salinity were 2 m and 33 g/L, and six species were recorded in the zooplankton. In 2009–2010, its maximum depth was 0.3 m, its salinity exceeded 230 g/L, and only Artemia persimilis was recorded. Field studies to compare the active zooplankton of a third period were combined with laboratory tests to ascertain the composition of the egg bank (flotation with sucrose) and zooplankton succession (hatching from sediments). In 2017–2018 (third period), the depth and salinity were 1.75 ± 0.17 m and 47.19 ± 11.40 g/L, respectively. Five species were recorded, and A. persimilis was found coexisting with cladocerans, copepods, and rotifers. Brachionus plicatilis, Hexarthra fennica, Boeckella poopoensis, A. persimilis, and a single specimen of Moina eugeniae were recorded in hatching experiments; however, the latter species was not recorded again. No cladoceran ephippia were recorded in the flotation tests. Salt accumulation on the sediments during the Utracan drought (2010–2016) would have deteriorated the ephippia. The register of M. eugeniae in 2017–2018 could be largely because of recolonization by waterfowl. The conservation of Utracan Lake is therefore advisable, and the same goes for other nearby saline lakes, which can act as sources of propagules that cross terrestrial areas through transport by wind or zoochory.

Limnological Review doi: 10.3390/limnolrev24030017

Authors: Elica Valkova Vasil Atanasov Margarita H. Marinova Antoaneta Yordanova Kristian Yakimov Yordan Kutsarov

The present study aimed to assess the pollution of Bulgarian brackish lakes based on their ability to accumulate the heavy metals Cd, Zn and Ni. Physicochemical parameters, including pH, electrical conductivity and salinity of the waters, were determined by potentiometric methods. The heavy metal content of the water and crustacean samples was determined by atomic absorption spectrophotometry. The highest pH in the investigated lakes (Atanasovsko Lake, Poda and Pomorie Lake) in the period May–September 2021 was found in the month of September, in the waters of Atanasovsko Lake (8.84). The concentrations of Cd measured in Atanasovsko Lake in the fall were in the order of 0.0125 µg/L—the highest value recorded for all the studied water bodies. The concentrations of zinc and nickel in the waters did not exceed the norms in Bulgarian legislation. The dynamics of biogenic elements (Zn and Ni) in crustaceans were inversely proportional to those found in the waters. The levels of the toxicant cadmium as well as the metals zinc and nickel in the species Gammarus spp. and Atremia spp., inhabiting all analyzed water bodies, were significantly lower than those specified in the Bulgarian and European legislation. The pH and electrical conductivity parameters of the tested waters, as well as the concentrations of the heavy metals, cadmium, zinc and nickel, were within the recommended values. High positive correlations were determined between the content of nickel, on the one hand, and cadmium and zinc, on the other, in the organism of the investigated crustaceans. A longer period of research is needed to accurately determine the degree of contamination of these waters.

Limnological Review doi: 10.3390/limnolrev24030016

Authors: Nina Sukhovilo Aliaksei Novik Vasil Vezhnavets

The investigation of lakes’ vulnerability to external impacts is essential for understanding and potentially mitigating the threats they face. By studying how lakes are affected by external factors, such as pollution, climate change and human activities, we can assess the health of the ecosystem and predict how it may respond to future changes. The purpose of this research is the analysis of climate change’s influence on the vulnerability of Belarusian lakes to external impact. The vulnerability indices were calculated using the randomized aggregate method. The dependences between parameters were defined on the basis of correlation and regression analysis. We investigated the vulnerability of 149 Belarusian lakes. Classifying the lakes allowed us to divide them into three types, with high, medium and low vulnerability to external impact. All the types include 2–3 subtypes. On the basis of classification, we created a zoning scheme for Belarus on the vulnerability of lakes to external impact. A forecast of lake vulnerability for three SSP scenarios to 2100 was conducted. In the SSP1 scenario, the vulnerability of stratified lakes will increase insignificantly. The vulnerability of homothermous lakes will not change. In the SSP2 scenario, the vulnerability of lakes will first increase then decrease. Lakes with high and medium vulnerability will be classed as medium- and low-vulnerable. In the SSP5 scenario, the vulnerability of lakes will decrease more significantly than in the other scenarios.

Limnological Review doi: 10.3390/limnolrev24030015

Authors: Heike Markus-Michalczyk Zairesus Smith Tjeerd J. Bouma

(1) Background: Willow forests are well established as nature-based solutions contributing to flood protection in the riverine environment. With climate change, storm surges in winter may increasingly expose downstream floodplain forests to seawater pulses. The effects of seawater pulses on willows are unknown, as previous studies focused on long-term exposure effects. (2) Methods: We studied the resilience of the floodplain forest foundation species Salix alba L. to seawater pulses during winter. This corresponds to the effects of storm surges in the North Sea region on floodplain willow trees in downstream river stretches during their dormant stage. Seawater pulses were applied from November to May on vegetative propagules. The plants were placed on flooding stairways at three levels in a mesocosm experiment under ambient conditions in Zealand, NL. (3) Results: Twice-applied 48 h seawater pulses during winter led to increasing salinity in the soil where vegetative propagules were placed. Ninety-five percent of the plants developed leaves, shoots, and roots, and juvenile trees were established in the following spring. Although the aboveground and belowground dry masses decreased with increasing short-term seawater flooding, they increased from April to May. (4) Conclusions: The seawater pulse caused a growth-delaying effect in the young experimental propagation plants of Salix alba. Contrary to earlier findings on the growth-inhibiting effects on S. alba under long-term salinity treatments, we show that S. alba is resilient to short-term seawater pulses experienced during the dormant (winter) stage. This is good news for the inclusion of S. alba in nature-based flood defense schemes in downstream riverine stretches.