Influenced by natural geographical conditions and intensity of human activities, the water environment of different areas in Erhai Lake exhibits significant differentiation. To analyze the spatiotemporal variation characteristics of the water environment in Erhai Lake, this study constructed water quality correlation networks at overall, annual, and quarterly scales for three lake regions (the north, middle, and south) based on 19 water physicochemical indicators monitored quarterly at the lake center and corresponding bays (Shaping Bay, Wase Bay, and Xiangyang Bay) from 2017 to 2024. The results indicate that: (1) The water quality network at the center of Erhai Lake is sparser and structurally simpler than that in the lake bays. This low connectivity and high modularity structure can localize disturbances such as pollution, thereby endowing higher resistance. In contrast, the bay networks are more complex and densely connected, making them more prone to chain fluctuations under external disturbances and having relatively weaker resistance; (2) The core nodes quality in the center lake network water are TN, TP, SD, and Chl.a, with TP serving as a common key driver. Its regulation can produce an efficient lever effect. Although water quality indicators in the bays have more connections, they possess fewer key nodes and rely more on random connected paths for buffering disturbances, thus having relatively lower stability; (3) The network structure of water quality in the bays undergoes seasonal evolution, gradually becoming more complex and compact from spring to winter, which may be jointly driven by seasonal fluctuations in rainfall runoff and aquatic plants. Therefore, by regulating the aquatic plant communities in the bays, the local network density can be reduced and modularity enhanced, thereby providing a key pathway toward simplifying and stabilizing the overall lake water quality network. This study is the first to incorporate the network stability framework into water quality assessment of plateau lakes. The proposed “water quality network structure characteristics” offer novel early-warning indicators (such as modularity and density) for zonal management of Erhai Lake and indicate the precise governance approach of reducing external loads and regulating aquatic vegetation to drive the network towards a more favorable configuration.

The construction of the Guxian Water Control Project causes blockage of river sections, hindering population exchange between fish upstream and downstream across the dam. Fish passage facilities can mitigate this barrier, and detailed knowledge of fish swimming behavior is critical for their effective design. This study targeted two main fish species for the project: Leuciscus waleckii Dybowski and Opsariichthys bidens-and tested their induced velocity and critical swimming speed. The study also analyzed ecological behavioral indicators including tail-beat frequency, tail-beat amplitude, body wave velocity, body wave length, maximum head angle, and maximum head angle velocity during upstream swimming at three swimming velocitys (2, 4, and 6 BL/s). The results showed that the absolute induced velocities of Leuciscus waleckii Dybowski and Opsariichthys bidens were (0.06±0.01) and (0.11±0.03) m/s, respectively, with corresponding relative values of (0.55±0.11) and (1.11±0.27) BL/s. The absolute and relative rheoreaction velocities of Leuciscus waleckii both exhibited significant negative correlations with body length (P<0.05), whereas the absolute rheoreaction velocity of Opsariichthys bidens showed a significant positive correlation with body length (P<0.05). The absolute critical swimming speeds of Leuciscus waleckii Dybowski and Opsariichthys bidens were (0.99±0.20) and (0.96±0.14) m/s, respectively, and the relative critical swimming speeds were (9.30±1.14) and (10.07±1.47) BL/s, respectively. Both absolute and relative critical swimming speeds of Leuciscus waleckii Dybowski were significantly positively correlated with body length (P<0.05). For both species, tail-beat frequency, body wave velocity, and maximum head angle velocity increased with flow velocity, while tail-beat amplitude and maximum head angle decreased with increasing flow velocity. The body wave length of Leuciscus waleckii Dybowski at 2 BL/s was significantly higher than that under the other two swimming velocitys (P<0.05), whereas the body wave length of Opsariichthys bidens showed no significant change with increasing flow velocity (P>0.05). Among the ecological behavioral indicators, tail-beat frequency, maximum head angle velocity, and body wave velocity showed the strongest correlations with swimming speed, suggesting their central role in propulsion. For fish-passage designs targeting Leuciscus waleckii Dybowski and Opsariichthys bidens, we recommended an entrance velocity of 0.9—1.2 m/s for upstream collection vessels and an internal velocity of 0.1—0.9 m/s within the collection chamber. This study quantifies the swimming ability and key swimming behavioral characteristics of two representative fish-passage target species, providing a reference for the design and optimization of fish passage facilities.

In order to find out the difference of rheotaxis between narrow range species Pseudorasbora elongata and widespread species Pseudorasbora parva, and whether differences in flow sensitivity contribute to their contrasting distribution patterns, with the aim of informing conservation measures for P. elongata. In this study, we examined the induction velocity for P. elongata and P. parva with the increasing velocity protocol. The results showed that absolute induction velocity (AIF) was (2.88±1.00), (6.81±1.20), (9.63±2.28) cm/s, and relative induction velocity (RIF) was (0.47±0.11), (0.83±0.11), (1.09±0.24) BL/s for body length of 5.0—6.9, 7.0—8.4, 8.5—9.0 cm for P. elongate, respectively. Both AIF and RIF differed significantly among length groups (P<0.05). The AIF and RIF for body length of 5.0—6.9, 7.0—7.9, 8.0—9.0 cm was (5.25±0.82), (7.34±0.46), (7.91±1.03) cm/s, and (0.83±0.10), (0.98±0.06), (0.94±0.10) BL/s for P. parva, respectively. Except for the groups between 7.0—7.9 cm and 8.0—9.0 cm, there were significant differences in AIF and RIF between the other body length groups (P<0.05). The AIF and RIF were positively correlated with body length for both two species (P<0.001). Independent-samples t test showed that the AIF and RIF of P. elongata were significantly lower than that of P. parva (P<0.05). The greater sensitivity of the narrow-ranged P. elongata to water flow, compared to the widespread P. parva, is likely a key factor constraining its distribution. Therefore, conservation of P. elongata habitats should fully account for its rheotactic characteristics. River realignment should follow natural variations in channel width and morphology while meeting flood-discharge safety requirements. In addition, in the sections where the P. elongata has been distributed, the density of lower head dams should be reduced to maximize free-flowing intervals, and removal should be considered where feasible.

The functional restoration of large river ecosystems represents a significant global challenge. The “Ten-Year Fishing Ban” implemented across the Yangtze River Basin, a large-scale ecological intervention, offers an unprecedented opportunity to investigate the recovery processes in a highly regulated aquatic ecosystem. This study aimed to comprehensively explore structural changes in the fish community food web in the tailrace of the Three Gorges Reservoir (TGR) after the fishing ban. We focused on two hydro-morphologically distinct river sections, the downstream Fuling section and the upstream Mudong section, to analyze the spatio-temporal responses of the food web. Our methodology integrated stable isotope analysis (δ¹³C and δ¹⁵N), an advanced Bayesian Isotope Mixing Model (BIMM) incorporating trophic-level constraints and prior dietary information, and food web topological analysis. Fish and basal food source samples were collected before (2018—2019) and after (2023) the ban implementation. Our results reveal that although species richness recovered similarly in both sections (increasing to 36 species each), food web restructuring followed two divergent pathways shaped by local habitat. The food web exhibited “vertical deepening”: connectance decreased from 0.085 to 0.070 and generalization index from 2.55 to 2.44, indicating more specialized trophic interactions. Concurrently, an expanded δ¹⁵N range (10.94‰ to 11.51‰) reflected food chain elongation, and the proportion of omnivorous species rose from 58.3% to 65.5%. These shifts, together with an increased piscivorous diet in the key predator Siniperca kneri, support a top-down recovery cascade driven by restored predator populations. In contrast, the riverine Mudong section underwent “bottom-up reorganization” toward a flatter structure: connectance increased from 0.070 to 0.077 and the generalization index from 2.21 to 2.69, suggesting more generalized feeding links. However, this was accompanied by a compressed δ¹⁵N range (11.77‰ to 10.47‰), indicating a shorter food chain, and a decline in omnivory from 65.4% to 55.2%. Isotopic data revealed greater reliance on terrestrial C3 plant-derived carbon sources. The diet of the key predator, Culter alburnus, shifted from 78.9% to 64.9%, reflecting increased use of lower-trophic-level resources. This pattern suggests that the recovery was primarily driven by enhanced primary production and terrestrial organic matter inputs, facilitated by stronger land-water coupling and Flood Pulse Concept. In conclusion, ecological recovery after a major conservation intervention such as the fishing ban is not uniform; trajectory depends on local environmental conditions such as flow velocity and floodplain connectivity. These findings underscore the critical importance of assessing functional attributes like food web structure alongside biodiversity metrics. This research provides a crucial scientific foundation for developing and implementing spatially differentiated, adaptive management in the Yangtze River Basin to improve the effectiveness of large-scale conservation efforts.

This study investigated the relationships among energy metabolism, personality traits, and social hierarchy in breeding-season rosy bitterling (Rhodeus ocellatus), with further analysis of sex-specific differences. The results showed that male R. ocellatus had significantly higher standard metabolic rate (SMR), maximum metabolic rate (MMR), and aerobic scope (AS) than females (P<0.05), indicating a greater metabolic potential in males, likely linked to the high-energy-demand activities during reproduction. In females, SMR was positively correlated with both MMR and AS (P<0.05). In males, SMR was positively correlated with activity, while MMR and AS showed significant positive correlations with aggressiveness (P<0.05). The observed sexual differences in the relationships between metabolism and personality may stem from the distinct selective pressures and behavioral strategies experienced by males and females during reproduction. In both sexes, only activity was significantly and positively correlated with social hierarchy (P<0.05), while metabolic rates showed no correlation with hierarchy. These findings suggest that social hierarchy in R. ocellatus is determined more by behavioral traits than by metabolic levels, and while sex influences the relationship between energy metabolism and personality, it does not affect the mechanism determining social hierarchy.

This study used the Soil and Water Assessment Tool (SWAT) to simulate the transport and export of butachlor, a typical herbicide, under agricultural non-point source pollution conditions in the Caizi Lake basin. Model calibration and validation indicated satisfactory simulation performance. The results revealed pronounced spatiotemporal variation in butachlor export. Temporally, 79.32% of the annual butachlor load occurred between June and July, closely associated with intensive rainfall and increased runoff following herbicide application in May–June. Daily butachlor export was significantly and positively correlated with daily runoff (P<0.01, r=0.632). Interannual differences were also evident, with export loads in wet years (e.g., 2016) substantially exceeding those in dry years (e.g., 2018). Spatially, the lower sub-watersheds (sub-basins 13, 17, and 19) were identified as primary export zones, with markedly higher outputs than upstream areas. Among land use types, water bodies had a significant effect on butachlor export, whereas cropland and forestland showed relatively weak impacts, highlighting the retention and transmission function of pond networks in multi-pond systems. These findings provide a scientific basis for managing agricultural non-point source pollution and pesticide use in the Caizi Lake basin, with important implications for safeguarding watershed water quality and optimizing regional agrochemical strategies.

The efficient underwater sensing and attack mechanisms of electric eels provide significant inspiration for the development of biomimetic equipment. To this end, this paper investigates the response strategies and discharge patterns of electric eels under various behavioral intents. By constructing specialized test scenarios and integrating behavioral recordings, data acquisition, and bio-electric field simulations, we systematically analyzed the correlation between attack/defense postures and discharge logic, as well as the corresponding discharge characteristics of electric organs. The results reveal that a curled attack posture enhances targeting efficiency through synergistic electric field and circuit interactions. Simulations indicate it can increase the voltage delivered to prey more than three times. Touch-based experiments further identified a deep-water passive defense mechanism through double/triple pulses. By comparing behavioral and electrogenic organ discharge (EOD) patterns in active and passive defense, this study concludes that active defense is suitable for shallow water, while passive defense is suitable for deep water environments, providing a more complete theoretical framework for understanding the different biological behaviors in electric eels.

As a crucial in-situ remediation technology for river and lake water bodies, ecological enclosure technology effectively inhibits pollutant diffusion, improves the aquatic environment, and enhances stability of river and lake ecosystems through multiple mechanisms such as physical isolation, chemical regulation, and biological enhancement. This paper reviews the operational mechanisms, types, and application effects of ecological enclosure technology in the ecological restoration and protection of rivers and lakes. Building on current literature, we identify existing limitations and propose future directions for both basic research and engineering applications. Future development should prioritize novel materials and technologies for key enclosure components while optimizing construction methods to ensure long-term stability and effectiveness. In addition, systematic numerical simulation methods should be incorporated to predict enclosure durability and ecological impacts, supporting the evolution of enclosure structures towards modularization and intelligence. Ultimately, the comprehensive performance of ecological enclosures should be improved under the premise of reducing management and operation costs and minimizing ecological risks. This study not only provides theoretical support for enhancing the stability and functionality of ecological enclosure technology but also offers technical references for professionals in the aquatic ecological restoration industry. It is expected to promote the sustainable application of this technology.