Largest Tributary Research Articles

Diatom metabarcoding as a tool to assess the water quality of two large tributaries of the Danube River

Diatom metabarcoding as a tool to assess the water quality of two large tributaries of the Danube River

Tracing drainage capture between the two large tributaries of the Yangtze River in the southeastern Tibetan plateau: Insights from detrital apatite fission-track thermochronology

The evolution of drainage patterns in the southeastern Tibetan Plateau remains a highly controversial topic. In this study, we provide solid evidence that the Dadu and Anning Rivers, located in the southeastern Tibetan Plateau, have undergone reorganization after the plateau uplift. Through detrital apatite fission-track dating on modern sediments from both rivers, as well as the upper Pliocene - lower Pleistocene Xigeda Formation of the Anning, we reveal that the modern sediments of the Dadu River are dominated by young AFT ages (<5 Ma), consistent with the bedrock ages in its drainage basin. Similarly, the Anning modern sediments and the Xigeda Formation exhibit a significant portion of young ages (peaking at 4.2 and 4.4 Ma, respectively), contrasting with the older ages observed in the bedrocks of the Anning drainage basin but comparable to those of the Dadu drainage basin. We conclude that the Anning and Dadu Rivers were connected during the deposition of the Xigeda Formation, and the modern Anning River receives significant recycled sediments from this formation.

Current nutrient load on Lake Onego from its largest tributaries

Current nutrient load on Lake Onego from its largest tributaries

OS MINERAIS PESADOS E IDADES DE ZIRCÕES DOS SEDIMENTOS DE PRAIAS (BARRAS EM PONTAL) DOS RIOS PURUS E ACRE NO ESTADO DO ACRE (BRASIL)

The Purus River and its largest tributary, the Acre River, originate in Peru and constitute the main drainage system for the northeast and southeast portions of the State of Acre. These rivers and their smaller tributaries develop their beds over the Solimões Formation (Miocene to Pliocene-Late) and form a broad dendritic drainage pattern. During the rainy season, due to the high rainfall in the region and the low resistance of the drained rocks, these rivers mobilize a large volume of sediment, which is deposited mainly during the dry season, forming beaches (pointed bars), predominantly composed of fine sand, silt and clay. To investigate the probable primary sources of these sediments and their possible geographic locations, a mineralogical and morphological study of their heavy minerals and a geochronological analysis of their detrital zircons were used. Heavy minerals were extracted from fractions between 0.062-0.125 and 0.125-0.250. The transparent ones were investigated using a petrographic microscope and the opaque non-magnetic ones, together with the lithic fragments using a Scanning Electron Microscope (SEM/SED). In descending order, the main transparent heavy minerals of the Purus River are epidote (19%), kyanite (17%), zircon (14.5%), andalusite (8%), tourmaline (7.4%) and sillimanite (5 .5%), in addition to these, in amounts less than 5%, staurolite, garnet, apatite, amphibole, chlorite, muscovite, biotite, anatase, pyroxene and cassiterite occur. With similar content and different proportions, the assemblage of heavy minerals from the Acre River consists of andalusite (22.5%), kyanite (22.5%), zircon (12%), epidote (8%), sillimanite (5%) and tourmaline (5%), its accessories are: garnet muscovite, chlorite, apatite, amphibole, biotite, staurolite, titanite, anatase, serpentine and rutile. The non-magnetic opaque minerals of both rivers were shown to be predominantly formed by ilmenite, and the ages obtained in the zircons varied from 180 Ma to 3000 Ma, with great frequency in the intervals between 200-400 Ma and 900-1200 Ma.

Анализ распределения видов флоры по высотным поясам бассейна реки Аргун

The Argun River is the largest river in the Sunzha basin. It originates on the Main Caucasian Ridge near the Chokismta-Matura peak (3189.7 m) in Georgia (historical region of Khevsureti). Before crossing the Lateral Ridge, it receives a large right tributary of the Andaki River (31 km long), whose sources are also on the Main Ridge near the Mal. Barbalo peak (3136 m). The length of the Argun River is 148 km, the total area of the basin is 3390 km2, it flows into the Sunzha River, a right tributary of the Terek River. In the upper reaches before the confluence with the right tributary, the Sharo-Argun River is historically called Chanty-Argun. Materials and methods. Materials and methods of research. Flora species and floristic complexes with different habitats within the Argun River basin were selected as the object of study. The material for the study was obtained during expeditionary trips for observations and herbarium collections in the period 2020–2023 in various altitudinal zones of the Argun River basin. Results and discussion. As a result of the research carried out in the Argun. Results. River basin, we recorded three groups of floras in the study area: plain-foothill, mid-mountain and high-mountain, the uneven distribution of floristic complexes in which made it possible to distinguish 6 floristic regions; More than half of the flora territory is located in the protected area system (2 reserves of republican significance, one of federal significance), 116 species are listed in the Red Books of the federal and regional levels, and another 16 species are proposed for protection. Discussion. The presence of narrow-local endemics in the flora also emphasizes its originality. It is advisable to include the entire Itum-Kalinsky floristic region in the territory of the Sovetsky biological reserve. Thus, many “Red Book” species, most of which are found only in this area, will be taken under real protection. These are Astracantha denudata, Berberis vulgaris, Сeltis glabrata, Cerasus incana, Cladochaeta candidissima Clenmatis integrifolia, Colutea orientalis, Cotynus coggygria, Crambe grandiflora, Dianthus daghestanicus, Ephedra procera, Fumana procumbens, Galanthus caucasicus, Gentiana grossheimii, Hippophaer hamnoides, Iris pumila, Gladiolus tenuis, Juniperus oblonga, Mandenovia komarovii, Medicago daghestanica, Notholaena maranthae, Omphalodes rupestris, Scabiosa rotata, Stipa caucasica, S. pennata, S. pulcherrima, Xanthobrychys majorovii. Conclusions. The total number of flora elements is significantly greater than the number of species in this area, since many of them are ecologically flexible and can be found in two or three vegetation zones, less often in four. Most species are confined to the steppe and forest zones, where the highest percentage of ruderal-segetal and alien species is observed, i.e. the quantitative composition is associated with anthropogenic impact on natural phytocenoses. The least number of species is in the subnival zone, where only petrophytes live, mostly endemics and subendemics.

Peak Flow Event Durations in the Mississippi River Basin and Implications for Temporal Sampling of Rivers

AbstractThe impact of an episodic river flood is intimately linked to its duration. Yet it is still unclear how often should a river be observed to accurately determine the occurrence and duration of extreme events. Here we assess flow statistics along with peak flow event detection and duration as a function of the discharge sampling period for large tributaries of the Mississippi basin using hourly gages over 2010–2022. Median event durations above high quantiles spatially vary from around 2 days upstream to 30 days downstream. Discharge mean, standard deviation, and quantiles can all be estimated within 2.5% error for sampling periods up to 8 days. A minimum temporal sampling 4× (2×) finer than peak flow event median duration is required to detect 95 ± 3% (85 ± 5%) of events and to estimate their duration within 90 ± 5% (75 ± 10%) median accuracy. Our findings have direct implications for future satellite missions concerned with capturing flood events.

Genetic Characterization of Endangered Sterlet (Acipenser ruthenus, Linnaeus 1758) Gene Bank Broodstock, Natural and Cultured Populations in Hungary

The sterlet (Acipenser ruthenus) is the smallest-bodied endangered species among the six native sturgeon species of the Danube River, and self-sustaining populations still inhabit the Hungarian section of the Danube River and its largest tributary, the Tisza River. Their populations are drastically decreasing; however, they still have natural reproduction in these habitats. For the genetic conservation of the species, an ex situ gene bank is maintained in Hungary. The present study aimed to analyze the genetic resources of a gene bank with a near 40-year history and to compare it with natural populations and farmed stocks. Twelve microsatellites were used for population genetics analyses and individual genotyping of 268 specimens from two natural habitats (Danube and Tisza Rivers) and three captive stocks (a gene bank broodstock and two farms). Microsatellites revealed similar patterns among wild populations and gene bank stocks and did not show genetic differentiation (FST: 0.016–0.017) among them. These results confirmed that the gene bank broodstock properly represents the genetic background of the Danube and Tisza populations and is suitable as a source of breeding materials for the restocking programs. Negative trends were detected in the farmed stocks, reflected in reduced polymorphism at a few loci. The results of the principal component analyses indicate the farm stocks’ separation from the wild and gene bank stocks. The present genetic characterization study reveals a valuable captive stock of the endangered sterlet populations and provides unique information about the genetic similarities and differences among farms and wild stocks in Hungary. Our results provide information that contributes to preserving the genetic structure and variability in sterlet populations and supports the management of gene bank broodstock—avoiding inbreeding and preserving the unique genetic background of the Carpathian basin.

A study of macroinvertebrate community structure and diversity in response to land use type in the Yiluo River Basin

Land use types have a significant impact on river ecosystems. The Yiluo River is the largest tributary below Xiaolangdi Reservoir in the middle reaches of the Yellow River, and is one of the important water conservation areas in the Yellow River Basin. Studying the ecological status of the Yiluo River under varied land use types in this basin is crucial for both ecological protection and the high-quality development of the Yellow River Basin. This study investigated the impacts of land use types on the macroinvertebrate community and functional structure in the Yiluo River Basin and introduced the concept of the land use health index (LUI). During the survey period, a total of 11,894 macroinvertebrates were collected, and 143 species were identified, belonging to 4 phyla, 7 orders, 22 families, and 75 families. The results showed that LUI had the most significant impact on macroinvertebrate community structure, with substrate type, dry plant weight, total phosphorus, turbidity, and attached algae biomass also playing significant roles in affecting macroinvertebrate communities. The species richness, the Shannon-Wiener index, and the Margalef richness index exhibited a nonlinear positive correlation with LUI of the sampling site, increasing as LUI enhancing and eventually reaching a plateau. Functional richness showed a linear and positive correlation with LUI, increasing with its enhancement, while functional evenness and functional divergence exhibited a nonlinear correlation with LUI. Functional evenness initially increased and then decreased with the enhancement of LUI, while functional divergence decreased with LUI enhancement. This study can provide a scientific reference for river ecological management under various land use scenarios.The Yiluo River is the largest tributary below Xiaolangdi Reservoir in the middle reaches of the Yellow River, and is one of the important water conservation areas in the Yellow River Basin. Studying the ecological status of the Yiluo River under varied land use types in this basin is crucial for both ecological protection and the high-quality development of the Yellow River Basin. This study investigated the impacts of land use types on the macroinvertebrate community and functional structure in the Yiluo River Basin and introduced the concept of the land use health index (LUI). During the survey period, a total of 11,894 macroinvertebrates were collected, and 143 species were identified, belonging to 4 phyla, 7 orders, 22 families, and 75 families. The results showed that LUI had the most significant impact on macroinvertebrate community structure, with substrate type, dry plant weight, total phosphorus, turbidity, and attached algae biomass also playing significant roles in affecting macroinvertebrate communities. The species richness, the Shannon-Wiener index, and the Margalef richness index exhibited a nonlinear positive correlation with LUI of the sampling site, increasing as LUI enhancing and eventually reaching a plateau. Functional richness showed a linear and positive correlation with LUI, increasing with its enhancement, while functional evenness and functional divergence exhibited a nonlinear correlation with LUI. Functional evenness initially increased and then decreased with the enhancement of LUI, while functional divergence decreased with LUI enhancement. This study can provide a scientific reference for river ecological management under various land use scenarios.

Complex Hepatectomy Under Total Vascular Exclusion of the Liver Preserving the Caval Flow with Portal Hypothermic Perfusion and Temporary Portacaval Shunt: A Proof of Concept.

Hypothermic liver perfusion decreases ischemia/reperfusion injury during hepatectomy under standard total vascular exclusion (TVE) of the liver. This surgery needs venovenous bypass and is hampered by high morbi-mortality. TVE preserving the inferior vena cava (IVC) flow is hemodynamically well tolerated but remains limited in duration when performed under liver normothermia. The objective of this study was to report the results of TVE preserving the caval flow, modified to allow hypothermic liver perfusion and obviate splanchnic congestion. The technique, indicated for tumors abutting large tributaries of the hepatic veins but sparing their roots in IVC and the latter, was applied when TVE was anticipated to last for ≥ 60 min. It combines continuous TVE preserving the IVC flow with hypothermic liver perfusion and temporary portacaval shunt (PCS). Results are given as median (range). Vascular control was achieved in 13 patients with excellent hemodynamical tolerance. PCS was direct or via an interposed synthetic graft (five and eight cases, respectively). Liver temperature dropped to 16.5 (6-24) °C under perfusion of 2 (2-4) L of cold perfusate. TVE lasted 67 (54-125) min and 4.5 (0-8) blood units were transfused. Resection was major in nine cases and was complete in all cases. Five complications occurred in four patients, and the 90-day mortality rate was zero. This technique maintains stable hemodynamics and combines the advantages of in situ or ex situ standard TVE with hypothermic liver perfusion, without their inherent prolongation of ischemia time and need for venovenous bypass.

Environmental DNA based biomonitoring for hatchery-raised fish in riverine habitats before and after recordable flood event

It is reported that the magnitudes of flood events in riverine systems have been increasing due to global climate change. Because flood events could displace fish species downstream and/or increase the mortality of fish, it is important to know how the increased floods can affect fish in river networks. In this study, we focused a hatchery-raised amphidromous fish, Ayu Plecoglossus altivelis altivelis in a mainstem-tributary network in Japan and examined the relative fish abundance changes before and after the recordable massive flood using the environmental DNA (eDNA) analysis. We also examined the spatiotemporal patterns of the Ayu eDNA concentrations and the relationships with tributary discharge, width, and depth to examine if the relative abundance changes could be related to tributary size. Our results indicated that Ayu tended to inhabit large, deep tributaries more than small, shallow tributaries even after the flood event. Further, the eDNA concentrations of Ayu have decreased in most study sites after the flood; however, the eDNA concentrations in certain tributaries with lower tributary size have increased during the study period. These results suggest that (1) the habitat conditions could be important for the maintenance of Ayu populations before and after flood events, (2) increase in flood magnitude along climate changes could have impacts on Ayu populations, and (3) not only large tributary, but also small tributaries could be important habitats for the target species to avoid flood disturbances.

Primary production of phytoplankton of the river Ob and the estuaries of its large tributaries in the site from the lower point of the Novosibirsk hydraulic system to the Novosondrovo (2022, 2023)

An assessment of the state of the river ecosystem was carried out. Ob based on the characteristics of the gross primary production of phytoplankton and BOD5 in the area from the lower pool of the Novosibirsk hydroelectric complex to the village. Novosondrovo (below the mouth of the Chulym River). The study was conducted in July 2022 and 2023. on the targets. The determination of gross primary production of phytoplankton was carried out using the flask method in oxygen modification in situ. At the same time, we determined the mineralization, transparency and temperature of water, pH, the content of oxygen dissolved in water, and the concentration of easily oxidized organic substances (BOD5) in the river. Ob and the mouth areas of Tom and Chulym. It was shown that the obtained values of the average gross primary production of Ob phytoplankton were significantly higher than in the summer low-water period in the Ob Bay and the upper reaches of the river. Yenisei. Particularly high rates were noted in areas subject to anthropogenic load and off the coast with a well-developed floodplain. The influence of tributaries on the functioning of Ob phytoplankton is shown. The key abiotic factors for the functioning of phytoplankton have been identified. It was revealed that, in terms of gross primary production and BOD5, the trophic status of the Ob and its tributaries during the studied period ranged from mesotrophic to polytrophic waters. The highest level of trophicity in 2022 was noted in local areas in the area of large settlements, in 2023 — in a more significant section of the Ob from the village. Dubrovino to the village. Krivosheino and at the mouth of the Tom, decreasing downstream the Ob to a mesotrophic level. It was noted that the trophic status of the Ob has increased significantly over the past 20 years, which may be a consequence of the increased anthropogenic load on the watercourse.

Endovenous laser ablation and drug treatment of acute great saphenous vein ascending thrombophlebitis: comparison of three approaches to the treatment of patients

Aim. In patients with acute thrombophlebitis of the great saphenous vein and/or large tributaries, compare the effectiveness and safety of 1,5-month fondaparinux sodium therapy and endovenous laser ablation in the area of the saphenofemoral junction in combination with shortterm anticoagulation or without anticoagulant therapy.Material and methods. This prospective, single-center, randomized, open-label clinical trial included 105 patients with acute great saphenous vein thrombophlebitis at a distance of at least 5 cm from the saphenofemoral junction. Thirty-four patients were randomized into the group of endovenous laser ablation in the area of the saphenofemoral junction without the anticoagulant therapy. The group of endovenous laser ablation in combination with 7-day fondaparinux sodium included 35 patients, while the group of 1,5-month treatment with fondaparinux sodium — 36. In all cases, class 2 compression stockings were used for 1,5 months. Clinical manifestations of venous thrombosis and its prevalence according to compression ultrasonography were assessed in the first 45±2 days from the start of treatment.Results. The mean age of patients was 49,1±13,7 years. There were more women (73,3%). The prevalence of risk factors for the occurrence and progression of venous thrombosis was low. Previous episodes of thrombophlebitis were observed in 3 (2,9%) patients. External factors that could provoke venous thrombosis were identified in 21 (20,0%) patients. Thrombosis was located in the great saphenous vein in 97,1% of patients, while large tributaries were involved in 25,7% of cases. The median distance from the proximal thrombus to the saphenofemoral junction was 45,2 cm. Patients randomized to the pharmacotherapy group were significantly older (mean age 49,1±13,7, 45,9±13,3 and 53,8±13,2 years, respectively; p=0,032), had slightly less pain and swelling. In all patients, after endovascular laser obliteration, a stable flow cessation at the intervention site was achieved. There were no cases of progression of venous thrombosis. After 7±2 days, in all groups there was a significant decrease in the proportion of patients with clinical manifestations of venous thrombosis, as well as the severity of persistent clinical manifestations. After 45±2 days, clinical manifestations were observed in a few patients and their severity was minimal. However, in the drug treatment group, a more frequent persistence of edema was noted both after 7±2 days (26,5, 20,0 and 47,7%, respectively; p=0,036) and after 45±2 days, (0, 2,9 and 16,7%, respectively; p=0,01). Hematomas and bruises were exclusive hemorrhagic complications. Hematomas were revealed in groups with endovenous laser ablation only. All hemorrhagic complication were minor according to World Society of Thrombosis and Hemostasis (ISTH) and type 1 according to Academic Research Consortium (BARC) classifications.Conclusion. In outpatients with low risk of recurrence and mainly distal localization of acute thrombophlebitis of the great saphenous vein and/ or large inflows, endovenous laser ablation close to saphenous vein junction without anticoagulation or with 7 days of anticoagulation and medical treatment with 1,5-month anticoagulation had comparable efficacy and invasive treatment was sufficiently safe.

Shoreline classification maps and ground truth data for the Neuse River Estuary, North Carolina

Estuaries provide essential ecosystem services and economic value but are facing widespread degradation due to changing anthropogenic and climatic factors. In North Carolina, coastal structures, like bulkheads and riprap, are widely used by property owners throughout the Albemarle-Pamlico estuary to stop erosion and reclaim lost land following storm events. While coastal development is tightly governed, limited historical and no up-to-date data report on the spatial distribution of coastal structures throughout the Albemarle-Pamlico estuary. Here we describe the development of a dataset that classifies and catalogues 67 km of shoreline type along the Neuse River Estuary (NRE), a large tributary of the Albemarle-Pamlico. We used available LiDAR digital elevation models (DEMs), aerial imagery, and a ground truthing field campaign to determine shoreline type present along the NRE as of 2020. We validated these results using an intensive manual editing procedure that comparatively examines DEMs, LiDAR derived slope, aerial imagery, and ground truth photography of the shoreline. This dataset is available for public download.

Arapaima gigas stocks have declined drastically in the lower Tocantins River in the Amazon Microregion.

Arapaima gigas, an emblematic species of the Amazon region and a longstanding primary fishing resource, currently holds a "Data Deficient" status on the International Union for Conservation of Nature Red List, and is listed as an endangered species in Brazil. The Tocantins River is the most extensively modified large tributary of the Amazon Basin, and thus can affect the dynamics of ichthyofaunal populations. Over a period of 1 year, representatives of the fishing communities and fishermen from 25 fishing communities from four municipalities in the lower Tocantins River region were interviewed, and the obtained information was evaluated based on the literature to survey the population abundance status of A. gigas in the region and its impact on local communities. Among the fishermen interviewed, only one reported still encountering and fishing A. gigas on Jaracuera Island. The disappearance of A. gigas in the region are viewed as having economically disastrous consequences for the residents. Additionally, other endemic fish species are no longer observed in this locality either. If fishery management officials do not work together with local communities, A. gigas could disappear from the northern region of Brazil, where information on the dynamics of A. gigas fishing is lacking.

Endovenous laser ablation of great saphenous vein and pharmacotherapy of acute ascending thrombophlebitis: results of a three-month follow-up

Aim. In patients with acute ascending thrombophlebitis of the great saphenous vein and/or its large tributaries, assess the incidence of venous thrombosis progression over 3 months with 1,5-month fondaparinux sodium therapy and endovenous laser ablation of the saphenofemoral junction in combination with short-term (7-day) anticoagulant therapy or without anticoagulation.Material and methods. This single-center, prospective, randomized, open-label study included data from 91 patients with acute ascending thrombophlebitis of the great saphenous vein and/or its large tributaries, of which 30 were in the group of endovenous laser ablation without anticoagulation, 32 — in the group of endovenous laser ablation in combination with 7-day fondaparinux therapy, and 29 — in the 1,5-month fondaparinux therapy group. Venous thrombosis progression rate within 90±2 days was assessed. Compression ultrasonography of lower limb veins was performed on days 7±2, 45±2 and 90±2 after randomization, as well as in case of thrombosis progression suspicion.Results. The mean age of patients was 49,4±14,2 years. There were more women (73,6%). There was a low prevalence of risk factors for the development and progression of venous thrombosis: obesity — 6,6%, type 2 diabetes — in 2 patients, class 2 heart failure — in 1, autoimmune disease (scleroderma in remission) — in 1, prior cancer — in 1. Previous episodes of thrombophlebitis were noted in 3 cases (3,3%). Following external factors provoking venous thrombosis were identified in 19 patients (20,9%): lower leg injury in 14, high physical activity in 3, long flight in 1, recent coronavirus disease 2019 in 1. Median duration of thrombophlebitis manifestations was 6 days. Thrombosis was located in the trunk of the great saphenous vein in 96,7% of patients, while large tributaries were involved in 29,7%. The median distance from the thrombus proximal part to the saphenofemoral junction was 42,5 cm. Over 90±2 days, there were no cases of involvement of the suprafascial segment of the perforating vein in thrombosis to the fascia level, spread of thrombosis to the deep veins, or pulmonary embolism. Subsequently, a new episode of superficial vein thrombosis was noted only in 2 patients from the pharmacotherapy group with a history of thrombophlebitis.Conclusion. In patients with a low risk of venous thrombosis progression and predominantly distal location of acute ascending thrombophlebitis of the great saphenous vein and/or its large tributaries after endovenous laser ablation, progression of venous thrombosis is not expected over the next 3 months, despite an anticoagulation reduction to 7 days or its refusal.

Identification of three stages of paleochannels and main source analysis beginning in the middle Pleistocene in the western Bohai sea in north China

Significant global sea transgressions–regressions have occurred under the influence of glacial–interglacial climatic change during the Quaternary period. Various types of paleochannels developed on the continental shelf of the western Bohai Sea as a result of sea level decline. Currently, the source of the paleochannels and the sedimentary environment and evolutionary pattern of the paleochannels are disputed. This study interprets high-resolution single-channel seismic data using a chronological framework based on accelerator mass spectrometry 14C (AMS14C) dating and optically stimulated luminescence (OSL) dating of core DZQ01. Furthermore, this research correlates this data with the cores of TJC-1 and H6 in the Western Bohai Sea and analyzes sedimentological characteristics based on grain size and clay mineral analyses. The results indicate that (1) three stages of paleochannels, namely Seismic Unit 6 (SU6), SU4, and SU2 are identified from bottom to top during Marine Isotope Stage 8 (MIS 8), MIS 6, and MIS 4, respectively; (2) from 300 to 243 cal. ka B.P., the SU6 paleochannel has four pathways, with the Yellow River serving as a primary source; from 191 to 130 cal ka B.P., the SU4 paleochannel has three pathways, and the main sources are the Yellow River, the Liao River, and the Luan River; from 74 to 14 cal. ka B.P., the SU2 paleochannels have two large tributaries, with the principal sources being the Yellow River and the Luan River. We, therefore, it can be inferred that the uplift of the Tibetan Plateau and glacial–interglacial climatic change constitute the formation mechanism for the paleochannels.

Estimating multiple years, tributary-specific, and overall Atlantic salmon smolt abundance in a large Canadian catchment using capture-mark-recapture experiments.

Population monitoring of Atlantic salmon (Salmo salar L.) abundance is an essential element to understand annual stock variability and inform fisheries management processes. Smolts are the life stage marking the transition from the freshwater to the marine phase of anadromous Atlantic salmon. Estimating smolt abundance allows for subsequent inferences on freshwater and marine survival rates. Annual abundances of out-migrating Atlantic salmon smolts were estimated using Bayesian models and an 18-year capture-mark-recapture time series from two to five trapping locations within the Restigouche River (Canada) catchment. Some of the trapping locations were at the outlet of large upstream tributaries, and these sampled a portion of the total out-migrating population of smolts for the watershed, whereas others were located just above the head of tide of the Restigouche River and sampled the entire run of salmon smolts. Due to logistic and environmental conditions, not all trapping locations were operational each year. Additionally, recapture rates were relatively low (<5%), and the absolute number of recaptures was relatively few (most often a few dozen), leading to incoherent and highly uncertain estimates of tributary-specific and whole catchment abundance estimates when the data were modeled independently among trapping locations and years. Several models of increasing complexity were tested using simulated data, and the best-performing model in terms of bias and precision incorporated a hierarchical structure among years on the catchability parameters and included an explicit spatial structure to account for the annual variations in the number of sampled locations within the watershed. When the best model was applied to the Restigouche River catchment dataset, the annual smolt abundance estimates varied from 250,000 to 1 million smolts, and the subbasin estimates of abundance were consistent with the spatial structure of the monitoring programme. Ultimately, increasing the probabilities of capture and the absolute number of recaptures at the different traps will be required to improve the precision and reduce the bias of the estimates of smolt abundance for the entire basin and within subbasins of the watershed. The model and approach provide a significant improvement in the models used to date based on independent estimates of abundance by trapping location and year. Total abundance and relative production in discrete spawning, nesting, or rearing areas provide critical information to appropriately understand and manage the threats to species that can occur at subpopulation spatial scales.

Midterm outcomes of endoscopic-assisted brachial-basilic arteriovenous fistula creation

Endoscopic vein harvest remains underused in single-stage brachial-basilic arteriovenous fistula creation. We analyzed our results with the use of this technique in a cohort of predominantly obese (body mass index ≥30 kg/m2) patients. Demographics, intraoperative details, and outcomes for all consecutive patients who underwent single-stage endoscopic-assisted brachial-basilic arteriovenous fistula creation between 2020 and 2022 at a single institute were analyzed retrospectively. The primary outcomes were technical success, fistula maturation, and primary assisted and secondary patency rates. Of the 11 patients (7 men; mean age, 62 ± 11.6 years), 7 (64%) already required dialysis at referral. The mean body mass index was 34 ± 7 kg/m2, 64% were obese, and an additional 27% were overweight. The medical comorbidities included hypertension in 11 patients (100%), diabetes in 7 (64%), and smoking in 8 (73%). Technical success was 100%, with no intraoperative complications. The median procedural length was 231 minutes (range, 183-302 minutes). Early complications in two patients (18%) included bleeding of the venous side branch requiring ligation and the loss of thrill requiring division of a tethering bridge of a large tributary. The maturation rate was 100%, and the brachial-basilic arteriovenous fistula was successfully accessed in all patients who required dialysis. At 12 months, the primary assisted and secondary patency rates were 90% ± 10% and 100%, respectively. Reintervention in seven patients (64%) included successful angioplasty in four, thrombectomy in two, and aneurysm resection with an interposition graft in one patient. Endoscopic vein harvest can be used for single-stage brachial-basilic arteriovenous fistula creation with good technical success and favorable maturation and patency rates, even for obese patients.

Atypical Forms of Lower Limb Varicose Vein Disease: Features of Diagnosis and Surgical Treatment

INTRODUCTION: Lower limb varicose vein disease (LLVVD) is the most common vascular disease with a predominant lesion of the main trunks of saphenous veins. At the same time, there exist atypical variants of lesion of the venous system in LLVVD, which cause difficulties in diagnosis and treatment.&#x0D; AIM: To study the incidence rate, anatomical bases of the varicose transformation, the features of reflux formation and the results of surgical treatment in atypical forms of LLVVD.&#x0D; MATERIALS AND METHODS: The study involved 600 patients with LLVVD, C2-C3 class of clinical manifestations in CEAP classification; 82 of them had atypical forms. The mean age of patients was 40.2 ± 9.2 years, duration of disease 15.0 ± 5.6 years. Duplex scanning of the lower limb venous system was conducted according to Russian recommendations for the diagnosis and treatment of chronic venous disorders of lower limbs of 2018. Patients with atypical forms of LLVVD additionally underwent computed tomography of the venous system with contrast. Surgical treatment of 50 patients with atypical forms of LLVVD included separation of the site of opening of a tributary in the area of saphenofemoral junction after preliminary marking and isolated elimination of varicose tributaries using Muller hooks; incompetent perforating veins were ligated at the epi- or subfascial levels depending on the location. The results were considered in the periods for up to two years.&#x0D; RESULTS: According to our data, the incidence of atypical forms of LLVVD was 13.7%. Lesion of the large tributaries of the main saphenous veins accounted for the highest proportion of atypical forms of LLVVD — 68.3%. Of these, varicose transformation of the anterolateral tributary made 98.2%, and of the superficial iliac circumflex vein — 1.8%. Isolated varicose transformation of perforating veins occurred in 31.7% of cases, where transformation of perforating veins of the gluteal area made 7.7%, of perforating veins of the posterolateral surface of the thigh — 46.2%, and of perforating veins of the patella region — 46.2%. The technical success in the postoperative period in the form of elimination of varicose saphenous veins and of the source of their incompetence was achieved in 100% of cases.&#x0D; CONCLUSIONS: The incidence of atypical forms of LLVVD is 13.7%, with the main trunks of saphenous veins remaining competent. The anatomical and hemodynamic basis for such forms of LLVVD is incompetence of the deep vein valves, from where the reflux is transmitted to tributaries of the saphenofemoral junction and/or perforating veins of the gluteal region, femoral region or popliteal fossa. Precise separation of varicose tributaries and perforating veins with preservation of the main trunks of subcutaneous veins is an organ-saving method of LLVVD treatment with a good effect in the follow-up period of up to two years.

Climate change increases the instability of the water supply for hydropower stations on the Tibetan Plateau

In recent decades, global warming has had a significant impact on the streamflow across the Tibetan Plateau. As the largest tributary in the upper reaches of the Yangtze River, the Yalong river is known for its abundant hydropower resources, and the world’s largest multi-energy complementary base has been built in the Yalong River Basin. However, prudent water resource planning is limited by the lack of long-term, detailed and reliable streamflow records over the Yalong river basin. Here, we develop an October–June streamflow reconstruction for the Yalong River, based on composite tree-ring chronology of Picea likiangensis from seven sampling sites. The reconstruction goes back to 1480 CE, and accounts for 46.5% of the instrumental streamflow variance during 1962–2012. This record indicates that the Interdecadal Pacific Oscillation and the Atlantic Multi-decadal Oscillation were the major contributing factors to streamflow variations. A significant and stable correlation with temperature was found over the past few centuries on the interannual scale. Projections suggest that future climate change may lead to more frequent flood disasters in the Yalong River Basin.