Search Results (203)

The decline of salmonid stocks in the Baltic Sea region is a matter of serious concern, prompting many countries to implement widespread stocking of artificially reared individuals to restore or enhance populations. While such interventions are intended to be beneficial, their efficacy remains a subject of ongoing debate. Artificially reared fish often face challenges in adapting to natural environments and may struggle to compete with wild counterparts, potentially leading to reduced growth rates and diminished overall fitness. This study evaluated the growth and physiological condition of naturally hatched versus artificially reared Salmo trutta juveniles during their first two years of life, prior to smoltification and seaward migration. The results demonstrated that stocked juveniles exhibited significantly slower growth, a higher incidence of fin damage, and a greater abundance of cultivable gut bacteria compared to wild individuals. Conversely, no significant differences were observed in blood parameters. Such growth retardation suggests potential difficulties in adaptation and recruitment. Consequently, while the release of artificially reared S. trutta fry facilitates the restoration of extinct populations, its capacity to enhance existing stocks within Baltic Sea riverine ecosystems may be limited. Full article

The threat of antimicrobial resistance in aquatic environments, particularly riverine systems, is escalating, in part due to effluents discharged from healthcare facilities. This issue has been recognized not only in Japan but also in other Asian countries such as Indonesia and Nepal. Nevertheless, existing research remains limited, prompting an investigation into the prevalence of antimicrobial-resistant bacteria in the upstream and downstream sites of environmental rivers. In 2024, six samples were collected from three rivers in Hyogo Prefecture, Japan; five samples from five river sites in Indonesia; and three samples from downstream sites of rivers in Kathmandu, Nepal. These samples were subjected to selective culture–based Next Generation Sequencing and resistome analyses, based exclusively on the selective culture of bacteria propagated on CHROMagar ESBL plates. In Japan and Indonesia, Pseudomonas, Stenotrophomonas and Acinetobacter were frequently detected, whereas Klebsiella was overwhelmingly predominant in Nepal. Significant differences in the similarity of bacterial community composition among sampling sites across the three countries were observed (p < 0.001). Notably, Nepal exhibited the highest abundance level of antimicrobial resistance genes among the three countries, largely consisting of β-lactam resistance genes. In conclusion, these analyses elucidated substantial differences in bacterial community composition and degrees of environmental contamination. Full article

Sediment management is defined as the strategic monitoring and control of erosion, transport, and deposition processes to maintain environmental and infrastructural stability. Terrestrial laser scanning (TLS) has emerged as a critical high-precision technology for monitoring sediment dynamics, erosion processes, and geomorphic change detection across diverse environments, including riverine, coastal, watershed, and infrastructure-related landscapes. While the field of TLS technology has seen significant advancements in recent years, including improvements in data accuracy, enhanced operational performance, artificial intelligence (AI), machine learning-based processing, and integration with other remote sensing tools such as unmanned aerial vehicles (UAVs) and satellite light detection and ranging (LiDAR), the study has focused on these developments. These advancements have further extended the application prospects of TLS technology. Despite these advancements, there remains a crucial need to systematically identify global research trends to identify the effectiveness, limitations, and knowledge gaps of TLS in sediment management. The methodological advantages and challenges of TLS applications provide insights into its gradual development role in enhancing sediment monitoring and environmental resilience. The objective of this study is to synthesize the current state of sediment management by conducting a systematic review of 108 peer-reviewed research papers retrieved from academic databases, including Google Scholar, ResearchGate, ScienceDirect, Scopus, and Web of Science, from 28 countries, published between 2000 and 2025. The study will evaluate the effectiveness of TLS methodologies in comparison to conventional techniques and management procedures, following the PRISMA 2020 guidelines. It will examine their capacity to enhance measurement accuracy, reduce error margins, and improve structural guidelines, particularly by advancing TLS technology through the integration of AI and machine learning (ML) algorithms. The findings of the study indicate that TLS and Iterative Closest Point (ICP) techniques can enhance the analysis of 3D models of dam deformation, ensuring improved structural monitoring and safety. The findings offer insights into the evolving role of TLS in sediment monitoring, emphasizing its potential for enhancing environmental management and climate resilience strategies. Furthermore, this review identifies future research directions to optimize TLS applications in sediment management through interdisciplinary approaches. Full article

Urban wetlands, encompassing both natural and constructed ecosystems, are vital for urban resilience. Understanding how plant functional traits adapt to these distinct habitats is crucial for ecological management. This study investigates the intraspecific variation and trait covariation patterns of the common reed (Phragmites australis) in two contrasting urban wetland types in Ganzhou City: a stagnant, engineered constructed wetland and a dynamic, natural riverine wetland. This contrast represents a key gradient in hydrological regime and anthropogenic influence. We measured 22 morphological and chemical traits to assess trait differences, variability (coefficient of variation), and correlation patterns. Volcano plot analysis revealed significant habitat effects: reed in natural wetlands exhibited higher levels of Cu, P, N, and leaf moisture content (LMC), whereas those in constructed wetlands had higher Ca content. Traits such as Na, Mn, and Al showed high intraspecific variability. Correlation analyses revealed significant trade-offs and integrations among traits, such as positive correlations between LMC and nutrients (K, Cu), and negative correlations between Ca and key leaf morphological traits. Principal component analysis (PCA) further confirmed a significant separation along PC1, driven primarily by nutrient elements (Cu, P, K) and LMC, with natural wetlands scoring higher. In contrast, PC2, associated with leaf morphological traits (e.g., leaf area, leaf width), showed no significant inter-habitat difference. Our findings demonstrate that P. australis employs distinct ecological strategies by adjusting its functional traits and resource allocation in response to different urban wetland environments. This highlights the critical role of intraspecific trait variation in plant adaptation and has important implications for wetland restoration and the design of constructed ecosystems. Full article

Chlorinated paraffins (CPs) are persistent, bioaccumulative, and toxic. In marine environments, most studies have focused on short-chain CPs (SCCPs) in animals, while medium-and long-chain CPs (MCCPs and LCCPs) in plants have been neglected. In this study, samples collected from kelp mariculture zones in different seasons were analyzed for the CPs’ contamination characteristics and spatiotemporal distributions in seawater and contamination profiles, bioaccumulation behavior, and dietary exposure risks in kelp. In seawater, the total concentration ranges of SCCPs, MCCPs, and LCCPs were 25.44–245.75, 8.24–27.19, and not detected at 3.26 ng/L, respectively. Spatially, the CP concentrations were influenced by industrial discharge, riverine inputs, and dilution effects, and were significantly higher in nearshore water than in offshore areas (p < 0.05). The concentrations were significantly higher in February than in May, which was attributed to emissions from winter heating and reduced vessel activity during a fishing moratorium. In kelp, the total concentration ranges of SCCPs, MCCPs, and LCCPs were 5.4–210.9, 0.007–0.87, and 0.0–4.45 ng/g wet weight, respectively. Kelp exhibited significant growth-stage-dependent bioaccumulation of CPs, with higher CP concentrations and bioaccumulation factors in its tender stage (February) than during its mature stage (May). Congener analysis revealed similar composition patterns between seawater and kelp. According to a dietary risk assessment (hazard quotient < 0.01), the potential health risks associated with kelp consumption are low. Full article

Urban point source pollution has been effectively controlled in recent years; however, rainfall-driven non-point source (NPS) pollution has become a major contributor to the deterioration of urban water environments. This study focuses on the plain river network region of Wuxi City in the Taihu Basin, China. By integrating field monitoring with coupled model simulations, this study upscaled results from the experimental plot to the urban-scale river network, enabling analysis of the full processes of pollutant inflow and transport and evaluation of the role of rainfall in regulating these dynamics. Field monitoring in the experimental plot demonstrated a strong correlation between the temporal dynamics of NPS pollutant inflows and rainfall characteristics. Further analysis using model simulations in the river network area revealed that rainfall, maximum 1 h rainfall, and rainfall duration were identified as the primary drivers of pollutant inflows, while early drought duration, rainfall intensity, and variance between rainfall per unit time exerted non-linear effects. Specifically, when early drought duration was approximately 6–7 days or when rainfall intensity ranged from 2.1 to 2.6 mm/h, riverine nitrogen (N) and phosphorus (P) concentrations and pollutant loadings reached their peaks. In addition, when the deviation of unit-time rainfall from the event mean was between 1.8 and 2 mm, the duration of increase in pollutants entering the river was the longest. This study provides quantitative evidence highlighting the influence of rainfall characteristics on nitrogen and phosphorus dynamics in plain river network urban rivers. The findings offer valuable insights into the remediation of urban black-odor water bodies. Full article

While harmful cyanobacterial blooms (HCBs) are extensively characterized in eutrophic lakes, the ecological dynamics of connected river networks remain oversimplified, obscuring the mechanisms of community assembly and toxin distribution across the lake–river interface. This study investigated the spatial heterogeneity of HCBs and microcystins (MCs) in the Lake Taihu watershed, revealing a complex functional divergence between lotic and lentic ecosystems. The rivers functioned as primary nutrient sources, with Total Nitrogen (3.35 ± 1.52 mg·L⁻¹) and Total Phosphorus (0.21 ± 0.22 mg·L⁻¹) concentrations being 1.7-fold and 1.8-fold higher, respectively, than those in the lake during peak periods. Conversely, the lake acted as a biological sink, supporting a peak cyanobacterial density (3.32 × 10⁷ cells·L⁻¹) nearly 1.5 times that of the river network. Phytoplankton community analysis revealed distinct ecological niches: while the lentic lake environment was almost exclusively dominated by colonial Microcystis (>90% relative abundance), the lotic river networks harbored a diverse assemblage with significant contributions from filamentous Oscillatoria and Dolichospermum. Correspondingly, intracellular MC (IMC) in the lake (up to 14.5 μg·L⁻¹) significantly exceeded riverine levels (generally <1.0 μg·L⁻¹). Despite these compositional differences, toxin dynamics exhibited strong bidirectional coupling (r > 0.75, p < 0.01), suggesting a spillover effect where the lake determines the watershed’s toxin burden during rivers outflow period. Redundancy Analysis (RDA) further elucidated that limnetic blooms were primarily regulated by water temperature and pH, whereas riverine communities were strictly constrained by hydrodynamic flow. Consequently, the health risk assessment revealed a highly heterogeneous landscape where, beyond the northern lake bays, specific semi-lentic river segments emerged as cryptic hotspots. These findings demonstrate that while nutrients fuel the system, hydrodynamic conditions act as the ultimate ecological filter determining the spatiotemporal distribution of cyanobacterial risks, necessitating an integrated approach to monitoring the entire lake–river continuum. Full article

Early detection and effective monitoring of aquatic environments are essential for detecting and mitigating potential ecological threats to aquatic organisms and for ensuring the sustainable management of freshwater ecosystems. Passive sampling is an emerging approach for environmental DNA (eDNA) collection in aquatic systems while active sampling involves controlled collection and filtration of water. This study evaluates active and passive sampling methods in a riverine system for detecting eDNA from Atlantic salmon (Salmo salar) and its lethal ectoparasite Gyrodactylus salaris. Sampling was conducted in the Sande River, Vestfold County, Norway. The loop-mediated isothermal amplification (LAMP) method was employed due to its high efficiency and specificity for amplifying target genes. The selected genetic markers were mitochondrial cytochrome B (Cyt B) DNA for S. salar and cytochrome c oxidase 1 (COX1) for G. salaris. The results indicate that host eDNA was readily detected using both sampling methods, whereas detection of G. salaris was more effective using active sampling. These findings provide valuable insight into optimizing eDNA detection protocols for both host and parasite, demonstrating specificity and sensitivity of LAMP in detecting the target organisms. This case study contributes to the development of conservation strategies aimed at preserving Atlantic salmon populations and freshwater biodiversity. Full article

Eutrophication is a form of pollution caused by elevated nutrient concentrations in water bodies, leading to excessive algal growth and subsequent oxygen depletion. This process poses significant risks to aquatic ecosystems and overall water quality. This study investigates the spatial distribution of eutrophication in the Almyros Stream, aiming to develop a rapid and high-resolution approach for identifying eutrophication patterns and selecting representative sampling sites. Almyros is an urban stream in the western Heraklion Basin (Crete, Greece) that is subjected to considerable pressures from agricultural, industrial, urban, and tourism-related activities. Data for this study were collected using a drone equipped with a multispectral sensor. The multispectral bands, together with remote sensing indices associated with chlorophyll presence, served as input data. Chlorophyll presence is a key indicator of phytoplankton biomass and is widely used as a proxy for nutrient enrichment and eutrophication intensity in aquatic ecosystems. The k-means clustering algorithm was then applied to classify the data and reveal the eutrophication spatial patterns of the study area. The results show that the methodology successfully identified spatial variations in eutrophication-related conditions and generated robust eutrophication pattern maps. These findings underscore the potential of integrating remote sensing and machine learning techniques for efficient monitoring and management of water bodies. Full article

Riverine bacteria are vital to geochemical cycling, climate change, and water environments, and the relative research requires knowledge from multiple disciplines, including microbiology, ecology and river dynamics. The influence of river dynamics and morphology on riverine bacteria is drawing increasing attention; yet, there are few comprehensive reviews on the riverine bacteria from the perspective of river dynamics. Therefore, this paper systematically reviews the research progress from the perspective of river dynamics, focusing on the research techniques and methods of riverine bacteria, the impact of hydrodynamic conditions, the ecological effects of dam construction, and the spatial distribution pattern of river bacteria. The review indicates that hydrodynamic processes and human activities such as dam construction drive community reorganization of planktonic and sedimentary bacteria across scales from microhabitats to macrolandscapes by altering aquatic environments, promoting microbial interactions, and affecting diversity, thereby shaping their complex spatiotemporal distribution patterns. Finally, this paper looks forward to future research directions, emphasizing the need to further reveal the diversity of planktonic and sedimentary bacteria, their genetic functions and community construction mechanisms, and to deeply analyze the feedback driving relationship between hydrodynamics, river morphology and riverine bacteria. Full article

Microplastics (MPs) and nanoplastics (NPs) have emerged as pervasive pollutants across different aquatic systems on a global basis, yet integrated assessments linking wastewater, riverine, and marine environments remain scarce. The present study provides the first comprehensive evaluation of MPs in three interconnected aquatic matrices of Northern Greece, namely surface seawater from the Thermaic Gulf, surface freshwater from the Axios River, and influent and effluent wastewaters from the Thessaloniki WWTP (Sindos). During two sampling periods spanning late 2023 and spring 2024, suspected MPs were isolated, morphologically classified by stereomicroscopy, and chemically characterized through pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). MPs were ubiquitously detected in all substrates, exhibiting distinct spatial and compositional patterns. Seawater samples displayed moderate concentrations (1.5–4.8 items m⁻³) dominated by fibers and fragments, while riverine samples contained slightly higher levels (0.5–2.5 items m⁻³), enriched in fibrous forms and polyolefins (PE, PP). Wastewater influents showed the highest MP abundance (78–200 items L⁻¹; 155.6–392.3 µg L⁻¹), decreasing significantly in effluents (11–44 items L⁻¹; 27.8–74.3 µg L⁻¹), corresponding to a removal efficiency of 81–87.5%, being the first indicative removal efficiencies in a Greek WWTP. Among the different polymers detected, polyethylene, polypropylene, and poly(ethylene terephthalate) were identified as the most prevalent polymers across all matrices. Interestingly, a shift toward smaller size classes (125–500 µm) in effluents indicated in-plant fragmentation processes, while increased concentrations during December coincided with increased rainfall, highlighting the influence of hydrological conditions on MP fluxes. The combined morphological and polymer-specific approach provides a holistic zunderstanding of MP transport from inland to marine systems, establishing essential baseline data for Mediterranean environments and reinforcing the need for integrated monitoring and mitigation strategies. Full article

The SE Baltic area, the former Eastern Prussia, is renowned for complex natural history. Over the past millions of years, the area experienced major geological events and geomorphic landscape transformations, resulting in the present relief configuration. Past climates and environments gave rise to the specific life-forms that proliferated in the Paleozoic and Mesozoic–Early Cenozoic shallow sea/lacustrine basins, and the Late Cenozoic riverine and continental settings. During the Paleogene, forested sub-tropical lands and deltaic settings of coastal sea lagoons gave rise to the famed amber formations (Blue Ground) hosting inclusions of resin-sealed insect and other small invertebrates that offer an unprecedented look into the 35–34 million-year habitats. Ferruginous sandstones, formed in shallow waters incorporating remains of thermophilous fauna—bivalves and gastropods, bryozoans, and sea urchins, among others—lie above the amber-bearing deposits. Oligocene–Miocene continental (riverine, lacustrine, and palustrine) conditions relate to the “Brown Coal Formation”, embedding a variety of fossil plants. Finally, the Quaternary Period brought dramatic geo-environmental shifts, with cyclic interstadial sea transgressions and massive glacial erosion events delivering fossiliferous erratics with an array of primitive Paleozoic and later Mesozoic life-forms. Overall, the extraordinary paleontology of the SE Baltic area adds, within its geological context, to the European geoheritage and the world natural heritage. Full article

Under global environmental change, the health of rivers and lakes on the “Asian Water Tower”—the Qinghai–Tibetan Plateau—is facing mounting pressures. This study examines Qinghai Lake, the Huangshui River, the Golmud River, and the Qinghai reach of the Yangtze River. By integrating the Water Quality Index (WQI) with the AHP–TOPSIS framework, we develop a multidimensional assessment system encompassing water resources, water environment, aquatic ecology, and management functions. The WQI results reveal pronounced spatial heterogeneity in water quality, with conditions ranked as Golmud River > Yangtze River > Huangshui River > Qinghai Lake. Dominant controlling factors also shift from dissolved oxygen in riverine systems to total phosphorus in the lake environment. The comprehensive AHP–TOPSIS evaluation further shows a health ranking of Yangtze River (0.736) > Golmud River (0.602) > Qinghai Lake (0.404) > Huangshui River (0.297), leading to the identification of four distinct management pathways: ecological conservation, natural restoration, nutrient control, and pollution remediation. By moving beyond single-parameter diagnostics, this study provides a robust methodological basis for differentiated river–lake management. The proposed “one river (lake), one strategy” framework, coupled with red-line management recommendations grounded in key indicators, offers direct scientific support for systematic protection and precise governance of aquatic ecosystems on the Qinghai–Tibetan Plateau, contributing to national ecological security and high-level environmental stewardship. Full article

This study uses high-frequency monitoring across a river–barrier lake–reservoir continuum in the upper Minjiang River, southwestern China, to quantify the spatiotemporal dynamics and drivers of aquatic CO₂ partial pressure (pCO₂) and to identify the dominant controls under contrasting lotic and lentic conditions. River reaches were CO₂-supersaturated throughout the year, with higher pCO₂ in the wet season (mean 521 ppm) than in the dry season (421 ppm), indicating persistent CO₂ evasion to the atmosphere. In contrast, the downstream canyon-type reservoir showed a pronounced seasonal reversal. During the wet season, surface-water pCO₂ averaged 395 ppm, about 24% lower than that of the river and below atmospheric levels (~419 ppm); more than 55% of observations were undersaturated, with minima as low as 141–185 ppm, indicating temporary CO₂-sink behavior. In the dry season, mean pCO₂ increased to 563 ppm, exceeding both riverine and atmospheric levels and returning the reservoir to a CO₂ source. The reservoir pCO₂ variability was governed by the interaction of hydrology and metabolism: rising water levels and longer residence times likely enhanced CO₂ accumulation from the decomposition of inundated organic matter, while warm temperatures, high light and monsoon-driven nutrient inputs promoted phytoplankton growth that removed dissolved CO₂ and elevated dissolved oxygen, producing temporary sink behavior. In the river, short residence time and strong turbulence limited in-stream biological regulation, and pCO₂ variability was mainly driven by catchment-scale carbon inputs along the elevation gradient. Overall, our results demonstrate that dam construction and impoundment can substantially modify carbon cycling in high-mountain rivers. Under specific conditions (warm water, sufficient nutrients, high algal biomass), lentic environments may strengthen photosynthetic CO₂ uptake and temporarily transform typical riverine CO₂ sources into sinks, with important implications for carbon-budget assessments and reservoir management in mountainous basins. Full article

The Frontal Area Index (FAI) is a commonly used, cost-effective preliminary screening tool for identifying the Least Cost Path (LCP) of urban ventilated corridors and mitigating the Urban Heat Island (UHI) effect, particularly in situations where data and budget availability are limited. Although its theoretical basis and simulation studies have been extensively examined, empirical validation through field measurements remains limited. This study assesses the FAI method’s applicability in two representative U.S. Midwest cities—St. Louis and Chicago—and proposes key modifications based on field-measurement validation. FAI simulations were conducted to identify optimal ventilation corridors, and the results were subsequently compared with in situ field measurements. Our findings indicated a strong correlation between FAI predictions and field data in St. Louis. In contrast, significant discrepancies were observed in Chicago, where simulated ventilation performance did not align with measured conditions, revealing the standard method’s limitations in complex urban topographies. To address these shortcomings, this study proposes four modifications to enhance the model’s accuracy for U.S. Midwest cities: (1) adjusting the model for varying urban morphologies, (2) limiting the calculation scope, (3) implementing a distinct approach for riverine areas, and (4) adopting a plot-based division for areas with large-scale buildings. This research verifies and refines the FAI method, creating a more reliable tool for diverse urban contexts. The optimized approach provides robust support for wind environment analysis, ventilation corridor planning, and UHI mitigation strategies. Full article