Polycyclic aromatic hydrocarbons (PAHs), as a class of persistent organic pollutants (POPs), tend to accumulate in organisms due to their lipophilic. Penaeus vannamei, widely cultivated in such settings, is particularly susceptible to PAHs contamination, which may ultimately endanger human health. In this study, the contamination characteristics, ecological risks, and human health risks of 16 PAHs in a cultured water-biological system were investigated. Results showed that the total concentrations of the 16 PAHs (∑PAHs) in aquaculture water ranged from 44.62 to 350.46 ng/L, with Nap, Phe, BaA, Pyr, Chr, Flu, and Ace being the main pollutants. Pollution source analysis based on characteristic ratios showed that PAHs originated primarily from oil, coal combustion, and other biomass combustion. In shrimp muscle, the total concentrations of 16 PAHs ranged from 0.34 to 208.37 μg/kg (dry weight, dw), with 12 PAHs detected, and LMW PAHs predominated, while 5- and 6-ring PAHs accounted for minor proportions. The ILCR values associated with dietary exposure to shrimp ranged from 1.08×10^–11—2.02×10^–8, which was much lower than the USEPA standard value of 1×10^–6, indicating negligible carcinogenic risk under current conditions.

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.

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.

To investigate the impact of the ten-year fishing ban on fish community structure and diversity, this study conducted fish resource surveys in four sections of the middle Yangtze River—Zhijiang, Jianli, Yueyang, and Huangshi—during the spring and autumn seasons from 2022 to 2024. A total of 91 species belonging to 15 families and 10 orders of fish were investigated. Cyprinidae fish are the most abundant (59 species, 64.84%), with lake-type fish (47.25%) and omnivorous fish (65.93%) being the predominant ecological types. Relative Importance Index (IRI) analysis identified eight dominant species: silver carp, bighead carp, crucian carp, grass carp, silver bream, snakehead, shortjaw goby, and yellow catfish, predominantly medium-to-large economic fish. In 2024, 72 fish species were monitored in the middle reaches of the Yangtze River, representing an increase of 10 species compared to 2022, while the average catch per unit effort (CPUE) rose by 11.35% to 10.40 kg per haul. The Shannon-Wiener diversity index remained relatively stable (3.06—3.22). The abundance/biomass comparison curve indicated low disturbance in the fish communities. Cluster and NMDS analyses separated the fish community into two distinct clusters: Zhijiang formed one cluster, while Jianli, Yueyang, and Huangshi formed another. Following the implementation of the 10-year fishing ban in the Yangtze River, CPUE showed an upward trend. Key fish resources such as the four major carp species and croaker recovered relatively quickly, indicating phased success of the ban. However, the diversity index remained relatively stable, suggesting that species diversity recovery is a long-term process. These findings provide scientific support for evaluating the effectiveness of the fishing ban and dynamically adjusting related policies.

To understand the diversity characteristics and interannual variations of the fish community in the middle reaches and tributaries of the Huishui River during the early stage of the fishing ban, fish resource surveys were conducted from 2021 to 2023. A total of 59 fish species were collected, belonging to 40 genera, 12 families, and 7 orders. Among them, Cyprinidae fish were in an absolute dominant position, accounting for 67.80% of the total species, 89.22% of total abundance, and 91.65% of total biomass. The ecological types are dominated by benthic, omnivorous, and spawn-laying fish, with the proportions of species being 55.93%, 55.93%, and 44.07% respectively. Interannual characteristics showed that species richness ranged from 35 to 49, among which the common dominant species were Zacco platypus and Acrossocheilus fasciatus. The Margalef index, Shannon-Wiener index, and Pielou index all showed a fluctuating upward trend overall, ranging from 4.18—5.34, 1.97—2.37, and 0.55—0.62, respectively, while the Simpson index showed a downward trend from 0.19 to 0.31. Cluster analysis showed that community structure in spring, summer, and winter of 2021 was similar, as was that in winter of 2022 and winter of 2023; all other sampling occasions grouped together. This suggests that community recovery followed distinct phases, with a unique response pattern in the early stage (2021). Spatially, the main stream and tributaries generally formed separate clusters, indicating that habitat-driven differences remained dominant. Overall, the recovery of community structure was driven by multiple factors under temporal dynamics, including habitat conditions and seasonal variation, exhibiting phased progression and spatial heterogeneity. This research clarifies the characteristics and diversity trends of the fish community in the Huishui River during the initial stage of the fishing ban, providing a basis for the assessment of the fishing ban effect and the scientific management of aquatic biological resources.

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.

To investigate the effects of photoperiod on the feeding rhythms and gastrointestinal evacuation dynamics of second-instar juvenile Tachypleus tridentatus, this study examined diel feeding rhythms in second-instar juvenile T. tridentatus using eight observation time points over 24h under three photoperiod regimes: natural photoperiod, constant light, and constant darkness. Feeding rhythms were assessed via gastrointestinal satiety indices, and evacuation dynamics were tracked for 24h after satiation. The results showed that there were no significant differences in average satiety among time points within any photoperiod at 3h or 6h post-feeding. Under natural photoperiod at 3h, satiety was significantly higher at night than during the day, whereas no clear diel differences were observed under continuous light or darkness. By contrast, at 6h post-feeding, satiety indices were consistently higher at night than during the day under all three photoperiods. Feeding peaks under the natural photoperiod at 3h post-feeding occurred during the night-time period (21:00—06:00), while no distinct diel feeding rhythm was detected under continuous light or darkness. However, at 6h post-feeding, clear feeding rhythms emerged under both continuous light and continuous darkness, with feeding peaks occurring at 21:00—09:00, and 21:00—06:00, respectively. Most juveniles achieved substantial food intake within 3h, with only marginal increases observed by 6h. Gastrointestinal evacuation exhibited a biphasic pattern characterized by an initial rapid phase followed by a slower phase. First-time feeding juveniles reached 50% evacuation at 14.7h and 80% at 27.1h after satiation, whereas non-first-time feeding juveniles reached the same benchmarks at 8.8h and 16.3h, respectively. These findings demonstrate that second-instar juvenile T. tridentatus exhibit a pronounced diel feeding rhythm, only weakly influenced by photoperiod. Based on these results, it is recommended that juvenile rearing be conducted under a natural photoperiod with at least one feeding event after dusk and moderately extended during the early feeding stage. This study provides a scientific basis for optimizing feeding strategies in the artificial culture of juvenile T. tridentatus.

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.