Biogenic elements-informed assessment of the impact of human activities on river ecosystems.

River ecosystems, acting as pivotal conduits linking terrestrial, marine, and atmospheric realms, have faced significant disturbances due to human exploitation of their resources. Recent years have witnessed a heightened intensification of human activities, adversely affecting the equilibrium of water ecosystems. To systematically study the various factors that affect river ecosystems under human activities, we introduce a universally applicable approach that considers the diversity of watersheds, biogenic elements, and human activities. Using this method, this application uncovers the sensitive human activity types, biogenic factors, and species significantly influencing river biodiversity within the study area. Incorporating statistical modelling, sensitivity screening, and advanced correlation analyses within a random forest regression framework, Sensitive biogenic elements and biological types affected by human activities were identified in typical watersheds, and the stability of different aquatic ecosystems was evaluated. Suggestions for watershed management measures were proposed When human activities affect the degree of water resource development and utilization, the forms of sensitive biogenic elements include DIC and Tsi; When human activities affect the discharge of pollutants into rivers, the forms of sensitive biogenic elements include TP, PP, and DEP, and the ratio composition includes TC: TN, TC: TP, TP: TSi, and TN: TP, This study pioneers a novel method for assessing human impacts on river ecosystems and successfully applies this approach to inform management decisions for river segments and tributaries in the middle and upper reaches of the Yangtze River basin. thereby enhancing our understanding of the consequences of human-induced impacts on biodiversity.

Effect of fire and post-fire management on soil microbial communities in a lower subtropical forest ecosystem after a mountain fire.

Wildfires and post-fire management exert profound effects on soil properties and microbial communities in forest ecosystems. Understanding microbial community recovery from fire and what the best post-fire management should be is very important but needs to be sufficiently studied. In light of these gaps in our understanding, this study aimed to assess the short-term effects of wildfire and post-fire management on both bacteria and fungi community composition, diversity, structure, and co-occurrence networks, and to identify the principal determinants of soil processes influencing the restoration of these communities. Specifically, we investigated soil bacterial and fungal community composition, diversity, structure, and co-occurrence networks in lower subtropical forests during a short-term (<3 years) post-fire recovery period at four main sites in Guangdong Province, southern China. Our results revealed significant effects of wildfires on fungal community composition, diversity, and co-occurrence patterns. Network analysis indicated reduced bacterial network complexity and connectivity post-fire, while the same features were enhanced in fungal networks. However, post-fire management effects on microbial communities were negligible. Bacterial diversity correlated positively with soil microbial biomass nitrogen, soil organic carbon, and soil total nitrogen. Conversely, based on the best random forest model, fungal community dynamics were negatively linked to nitrate-nitrogen and soil water content. Spearman's correlation analysis suggested positive associations between bacterial networks and soil factors, whereas fungal networks exhibited predominantly negative associations. This study elucidates the pivotal role of post-fire management in shaping ecological outcomes. Additionally, it accentuates the discernible distinctions between bacterial and fungal responses to fire throughout a short-term recovery period. These findings contribute novel insights that bear significance in evaluating the efficacy of environmental management strategies.

Identification of hotspots of threatened inland fish species and regions for restoration based on longitudinal river connectivity.

Dams have reduced longitudinal river connectivity (LRC) worldwide, impairing habitat and migration opportunities for many freshwater fish species. However, national assessments linking LRC and threatened inland fish species distributions are lacking. Here, we show the trends in the LRC in China over the past 60 years, and quantitatively analyse their implications for threatened inland fish species. The average LRC in China decreased from 93.5% in 1960 to 25.1% in 2018, and the significant deterioration in LRC occurred over the last 20 years. Water resource regions with a high number of threatened fish species are concentrated in southern China, and the degree of threat to inland fish species increases with a decreasing average LRC. A total of 125 inland fish species are threatened by habitat degradation and loss, which is mainly caused by the construction of dams. Intrinsic factors and pollution are two other key threats to fish species in addition to the reduction of LRC. The results of this study can help us better understand the trends in LRC in China and their implications for inland fishes. Meanwhile, this study provides guidance for river management to help preserve biological diversity, including enhancing management of natural reserve areas, establishing ecological compensation mechanisms, preventing biological invasion, and monitoring and evaluation of restoration efforts.

Impact of cascade reservoirs on nutrients transported downstream and regulation method based on hydraulic retention time.

Cascade reservoirs construction has modified the nutrients dynamics and biogeochemical cycles, consequently affecting the composition and productivity of river ecosystems. The Jinsha River, as the predominant contributor to runoff, suspended sediment (SS), and nutrients production within the Yangtze River, is a typical cascade reservoir region with unclear transport patterns and retention mechanisms of nutrients (nitrogen and phosphorus). Furthermore, how to regulate nutrients delivery in the cascade reservoirs region is also an urgent issue for basin water environment study. Therefore, we monitored monthly variations in nitrogen and phosphorus concentrations from November 2021 to October 2022 in the cascade reservoirs of the Jinsha River. The results indicated that the concentrations and fluxes of total phosphorus (TP) and particulate phosphorus (PP) decreased along the cascade of reservoirs, primarily due to PP deposited with SS, while opposing trends for total nitrogen (TN) and dissolved total nitrogen (DTN), which might be the consequences of human inputs and the increase of dissolved inorganic nitrogen discharged from the bottom of the reservoirs. Moreover, the positive average annual retention ratios for TP and PP were 10% and 16%, respectively, in contrast to the negative averages of -8 % for TN and -11% for particulate nitrogen (PN). The variability in runoff-sediment and hydraulic retention time (HRT) of cascade reservoirs played crucial roles in the retention of TP and PP. A regulatory threshold of HRT = 5.3 days in the flood season was obtained for controlling the balance of TP based on the stronger relationship between HRT and TP retention ratio. Consequently, the HRT of these reservoirs could be managed to control nutrients delivery, which was of particular significance for basin government institutions. This study enhances our comprehension of how cascade reservoirs influence the distribution and transport patterns of nutrients, offering a fresh perspective on nutrients delivery regulation.

A flexible framework for regionalization of base flow for river habit maintenance and its thresholds.

Information on base flow for river habit maintenance (BFRH) and its thresholds is necessary for water resource utilization and protection. BFRH and its thresholds have significant spatial differences; however, it is still unclear how to identify and assess these characteristics. In this study, a technical framework was proposed to clarify the specific procedures and methods for regionalization of BFRH and its thresholds in large-scale areas. The framework includes four parts: construction of controlling factor system, sub-region division, identification of dominant factors, and determination of the thresholds in sub-regions. The framework was then applied to China to analyzed the regionalized characteristics of BFRH and its thresholds from a national perspective. The results illustrate the following: (1) the country is divided into nine sub-regions, and the controlling factors and their action paths to BFRH vary greatly. The elements of climate, vegetation, soil, topography and morphology are satisfactory in explaining the variance of BFRH and its thresholds, as R2 of the partial least squares structural equation modeling is between 0.503 and 0.848. (2) The value of BFRH/MAF (i.e. the proportion of BFRH to mean annual natural flow) differs greatly among sub-regions. The mean value is the largest in the Northwest Region, reaching 20 %, while it is only 1.7 % in the Northeast Cold Region. (3) The dynamic and static thresholds are obtained by using the precipitation and other indices as the explanatory variables in the sub-regions. In general, the more abundant the water resources, the higher may be the threshold. Moreover, attention should be paid to the positive and negative effects of vegetation restoration on this threshold. The case study proves that the framework can guide the determination of BFRH, especially for ungagged rivers. Importantly, the framework is flexible and highly adaptable in different regions.

Spatial-temporal variations of reference evapotranspiration and its driving factors in cold regions, northeast China.

Reference evapotranspiration ([Formula: see text]) is an important indicator for hydrometeorological change, which integrates atmospheric and surface conditions, and its downward trends have been reported in many regions over the past several decades. Cold regions constitute an important ecological barrier in China; however, few studies focus on change in [Formula: see text] in cold regions. Especially in the cold region of northeast China (CRNEC), as one of the national strategic grain bases, understanding spatial-temporal variations of [Formula: see text] is important for agriculture water management and ecological protection. This study selected the observations at 113 national meteorological stations located in CRNEC and evaluated the trends of [Formula: see text] and their driving factors from 1961 to 2017. Results indicate that annual [Formula: see text] increases from the northeast to the southwest of CRNEC and has an insignificant decreasing trend in the whole study period, in which 33 stations (29.2%) show significant decreasing trends and only 19 stations (16.8%) show significant increasing trends at the 95% confidence level. An abrupt change in [Formula: see text] data is detected from 1994. Reasons for this abrupt change in [Formula: see text] vary largely over the study areas. Analysis shows that wind speed and minimum air temperature are the two major factors that control the change of [Formula: see text] before 1994. It also shows that wind speed and actual vapor pressure are the two major controlling factors after 1994. We also found that [Formula: see text] shows a certain correlation with Pacific Decadal Oscillation and Western Pacific Index, but there is a significant correlation between meteorological factors and teleconnection factors related to [Formula: see text]. These findings will promote agricultural water management and improve water ecological protection in the CRNEC. We investigated changes in reference evapotranspiration relationships with atmospheric circulation and its attributions over the cold regions in northeast China during 1961 ~ 2017. The results indicate that the wind speed and minimum air temperature are the two major factors that control the change of ET0 before 1994, and wind speed and actual vapor pressure are the two major controlling factors after 1994. We also found that ET0 shows a certain correlation with Western Pacific Index in the whole period.

Variance-aware attention U-Net for multi-organ segmentation.

PURPOSE: With the continuous development of deep learning based medical image segmentation technology, it is expected to attain more robust and accurate performance for more challenging tasks, such as multi-organs, small/irregular areas, and ambiguous boundary issues. METHODS: We propose a variance-aware attention U-Net to solve the problem of multi-organ segmentation. Specifically, a simple yet effective variance-based uncertainty mechanism is devised to evaluate the discrimination of each voxel via its prediction probability. The proposed variance uncertainty is further embedded into an attention architecture, which not only aggregates multi-level deep features in a global-level but also enforces the network to pay extra attention to voxels with uncertain predictions during training. RESULTS: Extensive experiments on challenging abdominal multi-organ CT dataset show that our proposed method consistently outperforms cutting-edge attention networks with respect to the evaluation metrics of Dice index (DSC), 95% Hausdorff distance (95HD) and average symmetric surface distance (ASSD). CONCLUSIONS: The proposed network provides an accurate and robust solution for multi-organ segmentation and has the potential to be used for improving other segmentation applications.

Scenario analysis for the sustainable development of agricultural water in the Wuyuer River basin based on the WEP model with a reservoir and diversion engineering module.

Agricultural water use is increasing quickly with the rapid socioeconomic development observed in the Wuyuer River basin. Water withdrawal for agriculture over the past decade have seriously depleted the ecological water requirements in the basin and damaged the channel and downstream wetland ecosystems. Achieving sustainable development in the basin will require a balance between agricultural water exploitation and ecological water demands. In this paper, a reservoir and diversion engineering module was integrated with a dualistic distributed hydrological model (WEP model) to investigate the effects of agricultural water use on river discharge. Agricultural water shortages and yearly minimum river discharges between 2020 and 2050 under six agricultural water exploitation scenarios and one natural scenario were estimated based on the proposed model. The results showed that the dualistic hydrological process model was more suitable for basins with agricultural water resource exploitation and that the river discharge was significantly less than the natural discharge due to irrigation and reservoir filling, especially in drought years. Under the scenarios of high, middle and low water resource exploitation without ecological operations, agricultural development was unsustainable because of agricultural water shortages and ecological water scarcity. The evaluation of the guaranteed rates for the agricultural water supply and environmental flows showed that the low water resource exploitation scenario with ecological operations was the best option and that sustainable development could be achieved in the basin under this exploitation scenario in the future. However, implementing water management practices in the basin could result in certain economic losses. These losses could be offset by ecological protection funds for downstream wetlands. Overall, the model results could help to inform planning and investment decisions within the basin to improve the sustainable management of water resources.

The influence of cascade hydropower development on the hydrodynamic conditions impacting the reproductive process of fish with semi-buoyant eggs.

Hydropower projects have changed the physical habitat of rivers, which has a serious impact on the survival of local fish. The reproduction of fish producing semi-buoyant eggs requires a specific hydrodynamic condition. To predict the influence of cascade hydropower development on the reproductive process of fish with semi-buoyant eggs, a MIKE 21 Flow Model was applied. Lagrangian particle tracking was used to simulate the movement of semi-buoyant eggs and larvae using the Agent-based Modeling (ABM) lab module. The calibrated model showed good agreement between the simulated and observed data for the hydrodynamic process in the reservoir. Twelve scenarios were defined to fully understand whether fish with semi-buoyant eggs can reproduce naturally. The results showed the following: (1) It is difficult to form a fish migration passage in the reservoir in all potential scenarios. (2) Semi-buoyant eggs and larvae sank to the bottom and perished before they hatched and were old enough to survive, since the hydrodynamic conditions could not meet the minimum flow velocity required to keep them in the drift. (3) Even if the hydrodynamic conditions can keep them in the drift in impossible high-discharge conditions, there was not enough drifting time and distance in the reservoir. The results implied that fishes with semi-buoyant eggs cannot reproduce naturally in the main stream, but it is possible that they can reproduce successfully after the protection of the tributary. The method is transferrable to other locations via establishment of models with relevant data to a particular area.

Characterizing the Structural Pattern Predicting Medication Response in Herpes Zoster Patients Using Multivoxel Pattern Analysis.

Herpes zoster (HZ) can cause a blistering skin rash with severe neuropathic pain. Pharmacotherapy is the most common treatment for HZ patients. However, most patients are usually the elderly or those that are immunocompromised, and thus often suffer from side effects or easily get intractable post-herpetic neuralgia (PHN) if medication fails. It is challenging for clinicians to tailor treatment to patients, due to the lack of prognosis information on the neurological pathogenesis that underlies HZ. In the current study, we aimed at characterizing the brain structural pattern of HZ before treatment with medication that could help predict medication responses. High-resolution structural magnetic resonance imaging (MRI) scans of 14 right-handed HZ patients (aged 61.0 ± 7.0, 8 males) with poor response and 15 (aged 62.6 ± 8.3, 5 males) age- (p = 0.58), gender-matched (p = 0.20) patients responding well, were acquired and analyzed. Multivoxel pattern analysis (MVPA) with a searchlight algorithm and support vector machine (SVM), was applied to identify the spatial pattern of the gray matter (GM) volume, with high predicting accuracy. The predictive regions, with an accuracy higher than 79%, were located within the cerebellum, posterior insular cortex (pIC), middle and orbital frontal lobes (mFC and OFC), anterior and middle cingulum (ACC and MCC), precuneus (PCu) and cuneus. Among these regions, mFC, pIC and MCC displayed significant increases of GM volumes in patients with poor response, compared to those with a good response. The combination of sMRI and MVPA might be a useful tool to explore the neuroanatomical imaging biomarkers of HZ-related pain associated with medication responses.