Search Results (225)

Restoring longitudinal connectivity at small dams remains a significant challenge due to fluctuating reservoir levels that render traditional fish passes ineffective, this research focuses on the implementation of ecological flow, knowing that to this date, no passages in Romania have been designed to meet the bio-hydraulic conditions for longitudinal connectivity for a wide range of flows transiting through the passage. The proposed technical fish pass incorporates side valves that are individually operable to regulate water inflow across varying reservoir levels, thereby overcoming a significant drawback of conventional designs. A three-dimensional numerical model was developed using Computational Fluid Dynamics (CFD) to analyze the velocity fields and flow patterns within the basins under variable ecological flow regimes. To validate the numerical findings, an experimental investigation was conducted on a 1:10 scale physical model. The design’s primary objective is to ensure the passage remains functional despite fluctuating reservoir levels, offering a comprehensive and efficient solution for modern ecological flow management. Results indicate stable velocity profiles on the vertical slots, with values of approximately 1.1 m/s for the high-water regime and 0.85 m/s for the medium one, ensuring hydraulic conditions compatible with the swimming capacity of the targeted species. The results demonstrate that the proposed design effectively prevents high-pressure currents, ensuring a free surface flow suitable for ichthyofauna migration. Full article

Habitat fragmentation and human disturbance pose major challenges to bird movement and ecological connectivity, highlighting the need for effective ecological network construction in conservation planning. Although coastal ecological networks have received increasing attention, few studies have simultaneously examined seasonally explicit patterns, functional guild differences, and seasonally varying recreational disturbance. Using a coastal case study, we analyzed seasonal (spring, summer, autumn, winter) and guild-specific (wading birds, songbirds, raptors, and swimming birds) variations in bird ecological networks by integrating systematic field surveys (2023–2024) with citizen science records (2020–2025). Results indicated clear differences among guilds and seasons: swimming birds exhibited relatively complex and well-connected networks, whereas wading birds showed lower connectivity. Conservation priority areas varied markedly across seasons, being more extensive in spring (28.62%), autumn (23.69%), and winter (22.09%), but substantially reduced in summer (17.07%). Our findings provide a locally grounded reference for adaptive conservation planning in rapidly changing coastal landscapes, with particular attention to the protection and connectivity of coastal and estuarine wetlands for wading birds. Full article

Background: Neuromuscular electrical stimulation (NMES) is an effective exogenous neuromuscular activation method widely used in sports training and rehabilitation. However, existing research primarily focuses on land-based sports or single-joint movements, with limited in-depth exploration of its intervention effects and underlying neuromuscular control mechanisms for complex, multi-joint coordinated aquatic activities like breaststroke swimming. This study aimed to investigate the effects of NMES combined with traditional resistance training on neuromuscular function during sport-specific technical movements in breaststroke athletes. Methods: A randomized controlled trial was conducted with 30 national-level or above breaststroke athletes assigned to either an experimental group (NMES combined with traditional squat resistance training) or a control group (traditional squat resistance training only) for an 8-week intervention. A specialized fully waterproof wireless electromyography (EMG) sensor system (Mini Wave Infinity Waterproof) was used to synchronously collect surface EMG signals from 10 lower limb and trunk muscles during actual swimming, combined with high-speed video for movement phase segmentation. Changes in lower limb explosive power were assessed using a force plate. Non-negative matrix factorization (NMF) muscle synergy analysis was employed to compare changes in muscle activation levels (iEMG, RMS) and synergy patterns (spatial structure, temporal activation coefficients) across different phases of the breaststroke kick before and after the intervention. Results: Compared to the control group, the experimental group demonstrated significantly greater improvements in single-leg jump height (Δ = 0.06 m vs. 0.03 m) and double-leg jump height (Δ = 0.07 m vs. 0.03 m). Time-domain EMG analysis revealed that the experimental group showed more significant increases in iEMG values for the adductor longus, adductor magnus, and gastrocnemius lateralis during the leg-retraction and leg-flipping phases (p < 0.05). During the pedal-clamp phase, the experimental group exhibited significantly reduced activation of the tibialis anterior alongside enhanced activation of the gastrocnemius. Muscle synergy analysis indicated that post-intervention, the experimental group showed a significant increase in the weighting of the vastus medialis and biceps femoris within synergy module 4 (SYN4, related to propulsion and posture) (p < 0.05), a significant increase in rectus abdominis weighting within synergy module 3 (SYN3, p = 0.033), and a significant shortening of the activation duration of synergy module 2 (SYN2, p = 0.007). Conclusions: NMES combined with traditional resistance training significantly enhances land-based explosive power in breaststroke athletes and specifically optimizes neuromuscular control strategies during the underwater breaststroke kick. This optimization is characterized by improved activation efficiency of key muscle groups, more economical coordination of antagonist muscles, and adaptive remodeling of inter-muscle synergy patterns in specific movement phases. This study provides novel evidence supporting the application of NMES in swimming-specific strength training, spanning from macroscopic performance to microscopic neural control. Full article

Inspired by the Tesla valve, the island-type fishway is a novel design whose biological performance remains unelucidated. This study integrated hydraulic experiments, CFD modeling, and 3D computer vision to investigate the passage performance and swimming behavior of juvenile silver carp (Hypophthalmichthys molitrix). The results confirmed high biological feasibility, with upstream success rates exceeding 70%. The island and arc-baffle configuration create a heterogeneous flow field with an S-shaped main flow and low-velocity zones; each island unit contributes 8.9% to total energy dissipation. Critically, fish utilize a multi-dimensional navigation strategy to avoid high-velocity cores: temporally adopting an intermittent “rest-burst” pattern for energetic recovery; horizontally following an “Ω”-shaped bypass trajectory; and vertically preferring the bottom boundary layer. Passage failure was primarily linked to suboptimal path selection near the high-velocity main flow. These findings demonstrate that fishway effectiveness depends less on bulk hydraulic parameters and more on the spatial connectivity of hydraulic refugia aligning with fish behavioral traits. This study provides a scientific basis for optimizing eco-friendly hydraulic structures. Full article

Pseudomonas aeruginosa is a key indicator of hygienic and operational deficiencies in swimming pools, particularly in tourist facilities with high and variable user loads. This study reports the results of a four-year regulatory surveillance program (2016–2019) assessing P. aeruginosa contamination in tourist swimming pools in Andalusia, Spain. The program involved 14 hotels and 58 unique installations. A total of 2053 water samples collected from different installation types (outdoor and indoor pools, whirlpools, and cold-plunge pools) were analyzed using standardized ISO methods within the framework of Spanish legislation, and prevalence comparisons were based on proportion tests. The overall prevalence of P. aeruginosa was 5.1%, with marked differences among installation types, reflecting both variation in contamination rates and unequal sampling intensity. Whirlpools consistently showed the highest contamination rates, whereas indoor pools and cold-plunge pools exhibited lower prevalence. No significant differences were observed between chlorine- and bromine-treated pools, and contaminated samples were detected across the full range of disinfectant concentrations, including values within regulatory limits. Temporal analysis revealed that apparent seasonal peaks were installation-dependent rather than reflecting a uniform seasonal trend. Winter detections were confined to indoor pools and whirlpools, which remain operational year-round, while outdoor pools and cold-plunge pools were underrepresented during the low season due to reduced sampling. A marked increase in prevalence was observed in 2019, driven mainly by summer months and high-risk installations; however, this rise was not directly associated with tourist volume and does not support causal inference. These findings highlight the importance of installation-specific and operational factors in shaping P. aeruginosa contamination patterns. The study underscores the need for targeted surveillance strategies focusing on high-risk installations and for cautious interpretation of seasonal patterns in datasets derived from routine regulatory monitoring. Full article

Multi-fish tracking and behavior analysis in deep-sea cages face two critical challenges: first, the homogeneity of fish appearance and low image quality render appearance-based association unreliable; second, standard linear motion models fail to capture the complex, nonlinear swimming patterns (e.g., turning) of fish, leading to frequent identity switches and fragmented trajectories. To address these challenges, we propose SOD-SORT, which integrates a Constant Turn-Rate and Velocity (CTRV) motion model within an Extended Kalman Filter (EKF) framework into DeepOCSORT, a recent observation-centric tracker. Through systematic Bayesian optimization of the EKF process noise (Q), observation noise (R), and ReID weighting parameters, we achieve harmonious integration of advanced motion modeling with appearance features. Evaluations on the DeepBlueI validation set show that SOD-SORT attains IDF1 = 0.829 and reduces identity switches by 13% (93 vs. 107) compared to the DeepOCSORT baseline, while maintaining comparable MOTA (0.737). Controlled ablation studies reveal that naive integration of CTRV-EKF with default parameters degrades performance substantially (IDs: 172 vs. 107 baseline), but careful parameter optimization resolves this motion-appearance conflict. Furthermore, we introduce a statistical quantization method that converts variable-length trajectories into fixed-length feature vectors, enabling effective unsupervised classification of normal and abnormal swimming behaviors in both the Fish4Knowledge coral reef dataset and real-world Deep Blue I cage videos. The proposed approach demonstrates that principled integration of advanced motion models with appearance cues, combined with high-quality continuous trajectories, can support reliable behavior modeling for aquaculture monitoring applications. Full article

Locomotor disorders involving the spine are a major cause of impaired performance and early retirement in sport horses. Swimming is increasingly incorporated into rehabilitation protocols, but its effects on spinal biomechanics remain poorly understood. This prospective study evaluated changes in thoracolumbar mobility in sixteen sport horses diagnosed with cervical or thoracolumbar axial musculoskeletal lesions over a 12-week rehabilitation program comprising 4 weeks of land-based training followed by 8 weeks during which swimming sessions were incorporated three times per week. Weekly measurements of thoracolumbar flexion–extension range of motion (ROM) were performed during straight-line trot on a hard surface using inertial measurement units attached to the withers, T18, and tubera sacrale. Group-level analyses revealed minimal changes across training phases: in horses with thoracolumbar lesions, mean ROM decreased slightly during the second month of aquatic training (−0.1° [95% CI −0.1; 0], Cohen’s d = 0.2), whereas no significant variation was detected in horses with cervical lesions. As the study did not include a control group, these temporal changes cannot be specifically attributed to swimming and should be interpreted as descriptive rather than causal. Individual trajectories showed heterogeneous patterns, but these were not consistent enough to alter the group-level interpretation. Overall, the findings suggest that thoracolumbar mobility remains relatively stable throughout this type of rehabilitation program, highlighting the importance of individualized monitoring rather than the expectation of a uniform biomechanical response. Full article

Exercise training reduces metabolic dysfunction and improves neural function; however, its cortical molecular effects in diabetic–obese conditions remain unclear. Here, we aimed to identify transcriptional pathways by integrating physiological evaluation with an in silico analysis of cortical RNA-seq data from Zucker Fatty Diabetes Mellitus rats following a 12-week swimming training program. Exercise training reduced body weight and improved glucose control and blood pressure. RNA-seq analysis revealed 814 differentially expressed genes, with pathway enrichment highlighting glutamatergic synapse, retrograde endocannabinoid signaling, and oxytocin signaling pathways. These coordinated transcriptional shifts involved genes related to excitatory neurotransmission, neuromodulatory feedback, and calcium-dependent regulation. As hypothesis-generating models, these pathway-level patterns suggest that exercise training may modulate cortical signaling properties in diabetic–obese states and provide a conceptual framework for future mechanistic investigation. Full article

Major depressive disorder (MDD) was long framed as a single clinical entity arising from a linear stress–monoamine–hypothalamic–pituitary–adrenal (HPA) axis cascade. This view was shaped by forced swim and learned helplessness tests in animals and by short-term symptom-based trials using scales such as the Hamilton Depression Rating Scale (HAM-D) and the Montgomery–Åsberg Depression Rating Scale (MADRS). This “unitary cascade” view has been dismantled by advances in neuroimaging, immune–metabolic profiling, sleep phenotyping, and plasticity markers, which reveal divergent circuit-level, inflammatory, and chronobiological patterns across anxiety-linked, pain-burdened, and cognitively weighted depressive presentations, all characterized by high rates of non-response and relapse. Translationally, face-valid rodent assays that equated immobility with despair have yielded limited bedside benefit, whereas cross-species bridges—electroencephalography (EEG) motifs, rapid eye movement (REM) architecture, effort-based reward tasks, and inflammatory/metabolic panels—are beginning to provide mechanistically grounded, clinically actionable readouts. In current practice, depression care is shifting toward systems psychiatry: inflammation-high and metabolic-high archetypes, anhedonia- and circadian-dominant subgroups, formal treatment-resistant depression (TRD) staging, connectivity-guided neuromodulation, esketamine, selected pharmacogenomic panels, and early digital phenotyping, as endpoints broaden to functioning and durability. A central gap is that heterogeneity is acknowledged but rarely built into trial design or implementation. This perspective advances a plasticity-centered systems psychiatry in which a testable prediction is that manipulating defined prefrontal–striatal and prefrontal–limbic circuits in sex-balanced, chronic-stress models will reproduce human network-defined biotypes and treatment response, and proposes hybrid effectiveness–implementation platforms that embed immune–metabolic and sleep panels, circuit-sensitive tasks, and digital monitoring under a shared, preregistered data standard. Full article

The swimming crab, Portunus trituberculatus, is an important mariculture crustacean species in China. To quantitatively characterize its discontinuous and biphasic growth under intensive aquaculture conditions, we developed a modified growth model based on the dynamic energy budget (DEB) theory. The model incorporates a discontinuous growth representation that explicitly accounts for the molting process. Molting events were parameterized using a threshold ratio (α), defined as the carbon weight-to-wet weight ratio, with stage-dependent critical values derived from laboratory experiments and published datasets. Laboratory experiments were designed to estimate the energy-budget-related parameters together with data from the literature. In addition, by introducing a feedback mechanism for the energy demand of ovarian development, a set of κ values was calibrated with data from the literature to reproduce the stage-specific growth determined by ovarian development. The model was validated with growth data from several published studies related to the growth of P. trituberculatus, as well as measurements from the aquaculture ponds. Multiple goodness-of-fit indices (R-square, modeling efficiency, and Theil’s inequality coefficient) confirmed that the modified DEB model accurately reproduced both wet weight and ovarian growth trajectories, along with the characteristic non-continuous pattern of molting-driven wet weight increase. The individual growth model can be a useful tool for optimizing the intensive culture practice of the swimming crab in the aquaculture ponds and assessing the environmental impact of crab aquaculture. Full article

Chronic stress alters hypothalamic–pituitary–adrenal (HPA) axis function, affecting corticosterone regulation and adaptive responses. Understanding individual variability in stress adaptation requires identifying distinct HPA axis response patterns. Here, we assessed HPA axis sensitivity in male C57BL6 mice exposed to 30 days of chronic social defeat stress (CSDS). Negative feedback integrity was evaluated using the dexamethasone suppression test (DST), with corticosterone measured after saline or low-dose dexamethasone administration at days 10 and 30. Behavioral testing (open field, elevated plus maze, social interaction test, partition, social defeat, forced swimming test, sucrose preference test) and qPCR analysis of HPA-axis-related genes in the hypothalamus (Crh, Crhr1, Crhbp, Fkbp5, Nr3c1), pituitary (Pomc, Crhr1, Nr3c1, Nr3c2), and adrenal glands (Cyp11a1, Cyp11b1, Hsd11b1, Mc2r, Star, Fkbp5, Nr3c1) were performed. K-means cluster analysis identified three distinct response profiles differing in baseline and dexamethasone-suppressed corticosterone levels. Clusters also exhibited differences in behavioral phenotypes and HPA axis gene expression. Cluster 1 showed low basal corticosterone and an abnormal dexamethasone suppression response, without significant Crh or Crhbp dysregulation in the hypothalamus. Cluster 2 exhibited elevated basal corticosterone, a blunted dexamethasone response, anhedonia, and reduced immobility in the forced swim test; increased Crh and reduced Fkbp5 suggested enhanced glucocorticoid receptor sensitivity and sustained hypercortisolemia. Cluster 3, characterized by normal basal corticosterone and normal dexamethasone response, displayed upregulation of Crh and Crhbp, consistent with balanced and potentially adaptive HPA axis regulation under chronic stress. These results demonstrate that corticosterone response heterogeneity reflects distinct adaptive trajectories under chronic stress. Identifying behavioral and molecular markers of these strategies may advance understanding of stress vulnerability and resilience mechanisms, with implications for stress-related disorders. Full article

Vertical slot fishways represent critical ecological migration facilitation structures and have been globally implemented to restore fish passage. However, most studies to date focus primarily on fishway hydraulics and fish behavior, with limited investigation into sediment deposition effects that may compromise functionality. To address this gap, we integrated physical modeling and numerical simulations to systematically analyze sediment deposition in a vertical slot fishway and its impacts on common carp upstream migration. Results indicate that sediment deposition raised fish vertical swimming positions by an average of 5.0 cm, thereby reducing pool activity space by 5.2–20.2%, altering flow patterns, and disrupting carp bottom-migration behavior. Consequently, carp exhibited increased exploratory behavior and directional uncertainty. Moreover, sediment-induced vertical vortices elevated fish energy consumption, decreasing upstream migration success from 89% to 48%. Multiple linear regression confirmed that average sediment deposition height significantly affects both migration rate and vertical swimming positions, whereas mean deposition slope demonstrates negligible influence. This study elucidates the multifaceted impacts of sediment deposition on fishway efficacy, providing a scientific basis for optimizing designs to enhance migration success and long-term functionality. Full article

To evaluate the aquaculture potential of Amphioctopus kagoshimensis, we investigated the reproductive biology, embryonic development, and early paralarval morphology of Amphioctopus kagoshimensis under controlled laboratory conditions. Each adult specimen collected from the coastal waters of Fujian Province spawned approximately 4000–5000 eggs (mean ± SD: 4375 ± 478 eggs), with an overall hatching rate of 75% ± 10% (n = 2). Embryonic development lasted approximately 30 days at 22.0–24.5 °C and followed a classical 20-stage pattern. Hatchlings measured an average mantle length of 1.4 ± 0.1 mm and exhibited a merobenthic strategy, characterized by planktonic paralarvae with progressive morphological differentiation. The chromatophores appeared progressively on the head, mantle, arms, and funnel, with numbers increasing from 5 to 23 per arm by 30 days post-hatching. Paralarvae demonstrated active swimming, feeding behavior, and arm sucker development during rearing. By day 30, mantle length reached 2.5 mm, with significant growth in arm length and behavioral complexity. Its relatively small adult size (mantle length 8 cm), a moderate egg size (2.6 mm), fecundity and successful artificial incubation and 30-day paralarvae seedling suggested it may be a suitable model species for developmental studies and potential candidate for merobenthic octopod aquaculture in East Asia. Full article

The changes in water flow caused by hydropower projects and river diversions have had a profound impact on aquatic ecosystems, especially due to artificial structures such as dams and bridge piers. This study investigates the swimming behavior differences between single and dual fish in the wake region behind a D-shaped obstacle, using Percocypris pingi as the experimental species. The results show that single fish efficiently utilize vortex energy through the Kármán gait, improving swimming efficiency, while the dual-fish group failed to maintain a stable Kármán gait, resulting in irregular swimming trajectories. However, the dual-fish group optimized wake utilization by maintaining a fore–aft linear alignment, improving swimming efficiency and resisting vortices. The conclusion indicates that mutual interference in group swimming affects swimming efficiency, with fish adjusting their swimming patterns to adapt to complex hydrodynamic conditions. By altering swimming formations, fish schools can adapt to the flow environment, offering new insights into the swimming behavior of fish and providing theoretical support for ecological conservation and hydropower project design. Full article

This study focuses on the impact of wastewater discharges from the Besòs treatment plant on the coastal water quality of Barcelona, particularly under adverse weather conditions. A simplified mathematical model was developed to predict, in real time, the concentration of bacterial indicators (Enterococci and E. coli) along nearby beaches. This model aims to quickly detect contamination events and trigger alerts to evacuate swimming areas before water quality tests are completed. The simulator uses meteorological data—such as wind direction and speed, rainfall intensity, and solar irradiance, among others—to anticipate pollution levels without requiring immediate water sampling. The model was tested against real-world scenarios and validated with historical meteorological and bacteriological data collected over six years. The results show that bacterial pollution occurs mainly during intense rainfall events combined with specific wind conditions, particularly when winds blow from the southeast (SE) or east–southeast (ESE) at moderate to high speeds. These wind patterns carry under-treated wastewater toward the coast. Conversely, winds from the north or northwest tend to disperse the contaminants offshore, posing little to no risk to swimmers. This study confirms that pollution events are relatively rare—about two per year—but pose significant health risks when they do occur. The simulator proved reliable, accurately predicting contamination episodes without producing false alarms. Minor variables such as water temperature or suspended solids showed limited influence, with wind and sunlight being the most critical factors. The model’s rapid response capability allows public authorities to take swift action, significantly reducing the risk to beachgoers. This system enhances current water quality monitoring by offering a predictive, cost-effective, and preventive tool for beach management in urban coastal environments. Full article