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To better predict the timely variation of algal blooms and other vital factors for safer drinking water production, a new AI scanning–focusing process was investigated for improving the simulation and prediction of algae counts. With a feedforward neural network (FNN) as a base, nerve cell numbers in the hidden layer and the permutation and combination of factors, etc., were fully scanned to select the best models and highly correlated factors. All the factors involved in the modeling and selection included the date (year/month/day), sensor data (temperature, pH, conductivity, turbidity, UV254-dissolved organic matter, etc.), lab measurements (algae concentration) and calculated CO2 concentration. The new AI scanning–focusing process resulted in the best models with the most suitable key factors, which are named closed systems. In this case study, models with highest prediction performance are the (1) date–algae–temperature–pH (DATH) and (2) date–algae–temperature–CO2 (DATC) systems. After the model selection process, the best models from both DATH and DATC were used to compare the other two methods in the modeling simulation process: the simple traditional neural network method (SP), where only date and target factor as inputs, and a blind AI training process (BP), which considers all available factors as inputs. Validation results show that all methods except BP had comparable results for algae prediction and other water quality factors, such as temperature, pH and CO2, among which DATC displayed an obviously poorer performance through curve fitting with original CO2 data compared to that of SP. Therefore, DATH and SP were selected for the application test, where DATH outperformed SP due to the uncompromised performance after a long training period. Our AI scanning–focusing process and model selection showed the potential for improving water quality prediction by identifying the most suitable factors. This provides a new method to be considered in the enhancing of numerical prediction for the factors in water quality prediction and broader environment-related areas. [ABSTRACT FROM AUTHOR]

Lakes are terminal sink of PPCPs, since PPCPs were transported to aquatic system from wastewater treatment plant effluent. Meanwhile, the ecological risks caused by PPCPs to the lakes have aroused wide concern. This study investigated the presence and distribution of PPCPs in 19 typical lakes in Wuhan city; the short term and long-term ecological risk were assessed. The concentration of ten typical PPCPs and the correlation between PPCPs and water quality parameters were analyzed. Ten PPCPs were widely detected, showing that these PPCPs were abundant in the research region. The total PPCPs concentrations varied from 0.44 to 2.1 * 102 ng/L in water sample and ≤ 5.3 ng/g in sediments. According to the results, two nonsteroidal anti-inflammatory drugs (ibuprofen, naproxen) were predominated compared to other PPCPs tested in the lakes of Wuhan city. The Pearson correlation analysis revealed a substantial positive correlation (p < 0.01) between NH 4 +-N and ibuprofen concentration, indicating that ibuprofen could be produced from the same sources of NH 4 +-N. Some PPCPs has shown positive correlation (p < 0.01) with suspended particles in concentrations. A negative correlation in water-sediment distribution for PPCPs was also observed. The potential ecological risks of PPCPs to the lakes were further evaluated. Results implied that ofloxacin posed the highest potential short-term risk of all the ten PPCPs. Sulfadiazine, sulfamethoxazole and roxithromycin posed a potential long-term risk in Niushan lake. This study investigated PPCPs distribution on a large spatial scale in Wuhan lakes in the post-epidemic era and revealed the importance of ofloxacin control in Wuhan. The findings of this work suggests that the long-term management for lake ecosystems is crucial. [Display omitted] [ABSTRACT FROM AUTHOR]

The world's water ecosystems have been affected by various human activities. Artificial intelligence techniques, especially machine learning, have become an important tool for predicting the water quality of inland aquatic ecosystems. As an excellent biological indicator, chlorophyll-a was studied to determine the state of water quality in Lake Llanquihue, located in southern Chile. A 31-year time series (1989 to 2020) of data collected in situ was used to determine the evolution of limnological parameters at eight spaced stations covering all of the main points of the lake, and the year, month, day, and hour time intervals were selected. Using machine learning techniques, out of eight estimation algorithms that were applied with real data to estimate chlorophyll-a, three models showed better performance (XGBoost, LightGBM, and AdaBoost). The results for the best models show excellent performance, with a coefficient of determination between 0.81 and 0.99, a root-mean-square error of between 0.03 ug/L and 0.46 ug/L, and a mean bias error of between 0.01 and 0.27 ug/L. These models are scalable and applicable to other lake systems of interest that present similar conditions and can support decision making related to water resources. [ABSTRACT FROM AUTHOR]

In the macrobenthos of Lake Pleshcheyevo and the adjacent river sites, 112 lower definable taxa (LDTs) have been noted. Chironomids and oligochaetes continue to form the main part of the fauna. The greatest species richness and diversity are noted in the sublittoral zone, where the biocenoses of Dreissena polymorpha formed, and in the rivers adjacent to the lake. The appearance and mass development of the zebra mussel has had a significant impact on the benthos and ecosystem of the reservoir. According to the indicator organisms of the zoobenthos, there has been a decrease in the saprobity of the lake. [ABSTRACT FROM AUTHOR]

Landslide is one of the most common natural disasters in Indonesia. In Lut Tawar Lake, specifically the cliff side, the landslide event occurs almost daily. Mitigation effort becomes a necessity following the fatality cases it causes. This study aimed to identify landslides and suitable mitigation for the case of Lut Tawar’s lake cliff. A combined approach of landslide survey and image interpretation with field validation was used. In addition, local vegetation surrounding the case area was identified from the survey and interview process. The results showed there are in total 37 landslide points in the study area. The conducted analysis showed the landslide was mainly caused by land use change from forest to a plantation, slope, particularly in the cliff area that was carved for road development, the volcanic geology of Bukit Barisan mountain, rainfall intensity, and the equatorial rainfall characteristic of the study area. The results also suggest the finest solution for landslide mitigation, namely the eco-engineering approach, a revegetation method using the local vegetation. Local vegetation comprises multiple strata, of which grass in the below strata, shrubs in the middle strata, and trees in the upper strata, constitute a shield for the lake cliff. Within this structure, government and community can cultivate these plants in the surrounding lake area.

Chlorophyll-a (Chl-a) is an important parameter of water bodies, but due to the complexity of optics in water bodies, it is currently difficult to accurately predict Chl-a concentration in water bodies by traditional methods. In this paper, Sentinel-2 remote sensing images is used as the data source combined with measured data, and Ulansuhai Lake is taken as the study area. An adaptive ant colony exhaustive optimization (A-ACEO) algorithm is proposed for feature selection and combined with a novel intelligent algorithm of optimizing support vector regression (SVR) by genetic algorithm (GA) for prediction of Chl-a concentration. The ant colony optimization (ACO) algorithm is improved to select remote sensing feature bands for Chl-a concentration by introducing relevant optimization strategies. The GA-SVR model is built by optimizing SVR using GA with the selected feature bands as input, and comparing with the traditional SVR model. The simulation results show that under the same conditions, using A-ACEO algorithm to select feature bands as inputs can effectively reduce the model complexity, and improve the model prediction performance, which provides a valuable reference for monitoring Chl-a concentration in lakes.

Objective To discuss prenatal ultrasonographic characteristics of placental lake-like lesions and the significance of prenatal diagnosis of these lesions. Methods Six patients with prenatal placental lake-like lesions (maximal diameter>5 cm) detected by ultrasound were selected from Beijing Obstetrics and Gynecology Hospital, Capital Medical University from February 2016 to December 2021. Their demographic data, ultrasound features, clinical diagnoses and pregnancy outcomes were retrospectively analyzed. Results All the patients had a singleton pregnancy, aged 27-33 years at diagnosis, and were initially found with placental lake-like lesions at 18 weeks and two days of pregnancy to 31 weeks and 6 days of pregnancy. Lake-like lesions with clear margins with placenta were detected by ultrasound in cases 1, 2 and 3, all of them were clinically diagnosed with massive subchorionic hematoma (MSH) , then underwent ceserean section at less than 34 weeks but greater than 33 weeks of pregnancy, less than 30 weeks but greater than 29 weeks of pregnancy, and 32 weeks of pregnancy, respectively, and all of 3 neonates had hypospadias. In case 4, a lake-like lesion with definite border protruding into amniotic cavity was found, which spontaneously disappeared in minutes. Fetal growth was unremarkable during pregnancy. In follow-up, the lesion was decreased significantly. Final diagnosis was real large placental lake. In cases 5 and 6, lake-like lesions diffusely involved most part of placenta, with decreased normal placental tissues. Both cases were complicated by early-onset fetal growth restriction (all biometric parameters

The communities in the Bosomtwe basin depend on Lake Bosomtwe for their livelihoods. However, the lake has continued to experience human-driven degradation in recent times, partly attributed to lack of understanding of the communities’ perception of the environment. This situation challenges policies and management strategies aimed for conservation of the lake. We conducted a survey of the main anthropogenic perturbations of the lake, the level of awareness of the communities of anthropogenic interventions and their effects on lake health, and the effectiveness of its management practices using a structured questionnaire administered to 350 respondents. Data were analyzed using non-parametric Kruskal Wallis and Mann Whitney U-tests. Crop farming, fishing, fish mongering, animal rearing, timber harvesting, hospitality operations, washing, other trades, and illegal mining were the anthropogenic interventions of the most devastating consequence, promoted by a low level of education and environmental awareness. Although the regards for directives of the traditional authority to govern the lake declined subtly, the situation is worsening due to inadequate resources for the Bosomtwe District Assembly, the government agency responsible for coordinating the activities of stakeholders of the lake and providing an effective decision-making basis for its conservation. The results, which have direct practical implications for water management, suggest the need for well- coordinated policies and strategies for law enforcement and education of basin communities on the causes and effects of lake degradation.

Abstract Microbial communities play important roles in lake ecosystems and are sensitive to environmental change. However, our understanding of their responses to long‐term change such as eutrophication is limited, as long‐term lake monitoring is rare, and traditional paleolimnological techniques (pigments and microfossils) are restricted to a low taxonomic resolution, or organisms with well‐preserved structures. Sedimentary DNA (sedDNA) is a promising technique to reconstruct past microbial communities in sediments, but taphonomic processes and the ability of sedDNA to record bacterial pelagic history accurately are largely unknown. Here, we sequenced the 16S rRNA gene in triplicate sediment cores from Esthwaite Water (English Lake District) which has concurrent long‐term monitoring and observational data. The sediment record spanned 113 years and included an episode of increased nutrient availability from the 1970s, followed by a more recent decline. Trends in bacterial community composition were broadly similar among the three sediment cores. Cyanobacterial richness in the sediment cores correlated significantly with that of cyanobacteria in a 65‐year microscopy‐based monitoring record, and some known pelagic bacterial taxa were detected in the sediment. sedDNA revealed distinct shifts in community composition in response to changing lake physicochemical conditions. The relative abundance of cyanobacteria closely reflected nutrient enrichment, and Proteobacteria, Bacteroidetes, and Verrucomicrobia were relatively more abundant in recent sediments, while Chloroflexi, Firmicutes, Acidobacteria, Nitrospirae, Spirochaetes, and Planctomycetes declined in more recent sediments. Following lake restoration efforts to reduce nutrient enrichment, the relative abundance of cyanobacteria returned to pre‐1970 levels, but the bacterial community did not fully recover from the period of intense eutrophication within the time scale of our study. These results suggest that sedDNA is a valuable approach to reconstruct lake microbial community composition over the 100‐year time scale studied, but an improved understanding of DNA deposition and degradation is required to further the application of sedDNA in paleolimnology.

Abstract The Pasterze is Austria's largest glacier, and it is experiencing rapid downwasting and retreat. A mosaic of complex sedimentary deposits has been produced in recent years which have not hitherto been studied, yet provide excellent lessons into the facies distribution expected from a dying valley glacier. In this paper, a new glaciological–geomorphological–geological map is presented for the glacier in July 2021. Freshly exposed (since 2018) tills and flutes constitute a subglacial sediment–landform assemblage. An ice‐marginal sediment–landform assemblage comprises meltwater streams, a delta system and proglacial lake terrace deposits. The supraglacial assemblage, meanwhile, includes fossil englacial channel deposits revealed by ablation, together with debris bands, rockfall deposits and supraglacial channel deposits. Collectively, these sediment–landform assemblages constitute the building blocks of a dying glacier landsystem.

Microsporidia are a large group of obligate intracellular eukaryotic parasites. Recent studies suggest that their diversity can be huge in freshwater lake ecosystems especially in the < 150-µm size fraction. However, little is known about their hosts and therefore their impact on the trophic food web functioning. In this study, single cell analysis and fluorescence microscopy were used to detect new host-parasite association within rotifer communities in lake Aydat (France). Our analysis showed the existence of a potential new species belonging to the Crispospora genus able of infecting the rotifer Kellicottia with a high prevalence (42.5%) suggesting that Microsporidia could have a great impact on the rotifer populations' regulation in lakes. [ABSTRACT FROM AUTHOR]

One of the largest freshwater estuarine systems on Earth, Green Bay receives freshwater runoff from its land watershed and cold-water intrusions from Lake Michigan. Southern Green Bay is a designated area of concern (AOC) due to ecosystem degradation, contaminated sediments, and poor water quality. Successful restoration of aquatic systems requires a clear understanding of their circulation and thermal regimes. Using a state-of-the-art numerical ocean model, this study examines the effect of variability in tributary inflows and the related lake intrusions on the circulation and thermal regime in Green Bay and on the mass and heat fluxes between lower- and upper–Green Bay areas. Our findings indicate that tributaries influence the circulation and thermal regime, locally and throughout the bay, and that the impact is more significant in hydrologically wet years. Model simulations showed evidence of small net transport out of lower Green Bay. This analysis of the simultaneous effects of tributary flows and lake intrusions in Green Bay can contribute to understanding the dynamics of freshwater estuaries and improve the planning of future restoration projects. [ABSTRACT FROM AUTHOR]

Submerged aquatic vegetation (SAV) in lake littoral zones is an inland water wetland type that provides numerous essential ecosystem services, such as supplying food and habitat for fauna, regulating nutrient fluxes, stabilizing sediments, and maintaining a clear water state. However, little is known on how inland SAV quantities are changing globally in response to human activities, where loss threatens the provisioning of these ecosystem services. In this study, we generate a comprehensive global synthesis of trends in SAV quantities using time series (>10 years) in lakes and identify their main drivers. We compiled trends across methods and metrics, integrating both observational and paleolimnological approaches as well as diverse measures of SAV quantities, including areal extent, density, or abundance classes. The compilation revealed that knowledge on SAV is mostly derived from temperate regions, with major gaps in tropical, boreal, and mountainous lake‐rich regions. Similar to other wetland types, we found that 41% of SAV times series are largely decreasing mostly due to land use change and resulting eutrophication. SAV is, however, increasing in 28% of cases, primarily since the 1980s. We show that trends and drivers of SAV quantities vary regionally, with increases in Europe explained mainly by management, decreases in Asia due to eutrophication and land use change, and variable trends in North America consistent with invasive species arrival. By providing a quantitative portrait of trends in SAV quantities worldwide, we identify knowledge gaps and future SAV research priorities. By considering the drivers of different trends, we also offer insight to future lake management related to climate, positive restoration actions, and change in community structure on SAV quantities. [ABSTRACT FROM AUTHOR]

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Non-native fish have been shown to have deleterious impacts on freshwater ecosystems in New Zealand. Early detection is critical for their effective management. Traditional capture-based techniques may not detect newly introduced fish, especially if they are present in low abundance. Molecular techniques that target environmental DNA (eDNA) have been shown, in many instances, to be more sensitive, cost-effective and require lower sampling effort. However, appropriate sampling strategies are needed to ensure robust and interpretable data are obtained. In this study we used droplet digital PCR assays to investigate the presence of two non-native fish in New Zealand, the European perch (Perca fluviatilis) and rudd (Scardinius erythrophthalmus) in three small lakes. Samples were collected from water and surface sediment at near-shore and mid-lake sites. Probabilistic modelling was used to assess the occupancy of fish eDNA and develop guidance on sampling strategies. Based on the detection probability measures from the present study, at least six sites and five replicates per site are needed to reliably detect fish eDNA in sediment samples, and twelve sites with eight replicates per site for water samples. The results highlight the potential of developing monitoring and surveillance programs adapted to lakes, that include the use of assays targeting eDNA. This study focused on small shallow lakes, and it is likely that these recommendations may vary in larger, deeper, and more geomorphologically complex lakes, and this requires further research. [ABSTRACT FROM AUTHOR]

Mining areas and in particular those containing massive sulfides have left a heavy environmental legacy with soils and hydrographic networks highly contaminated with metals and metalloids as for example in the Iberian Pyrite Belt (Huelva, Spain). Here, we present new data on copper (Cu) isotopic composition of waters and solids collected along a continuum Mine (Tharsis)—River (Meca)—Lake (Sancho) in the Iberian Pyrite Belt. Our results show that the isotopic signature of pit lakes is spatially variable, but remains stable over the seasons; this signature seems to be controlled by water–rock interaction processes. The data obtained on the Meca River imply a number of attenuation processes such as decrease in the metal concentration by precipitation of secondary minerals. This is accompanied by preferential retention of the heavy isotope (65Cu) with a possibility of living organisms (e.g., algae) participation. The terminal Sancho lake demonstrated constant isotopic signature over the entire depth of the water column despite sizable variations in Cu concentrations, which can be tentatively explained by a superposition of counter-interacting biotic and abiotic processes of Cu fractionation. Overall, the understanding of the isotopic variations along the hydrological continuum is useful for a better understanding of metal element transfer within mining environments and surrounding surface waters. [ABSTRACT FROM AUTHOR]

The contents of total mercury (THg) and methylmercury (MMHg) were measured in Nansi Lake and its inflow river estuaries to investigate their spatial distribution characteristics and the geochemical relationships between THg, MMHg, and methylation rate (%MMHg) with mineral phases of the sediment. The contents of THg, MMHg, and %MMHg in the lake sediment were lower than those in the inflow river estuary sediment. Inputting of inflow rivers was primary source to THg and MMHg in Nansi Lake. The THg contents in the sediment decreased from the upper to the lower lake, while the MMHg contents indicated the opposite trends of spatial variations. The THg was significantly positively correlated with MMHg and %MMHg in estuarine sediment but has a significant negative correlation with MMHg and %MMHg in lake sediment. Total organic carbon (TOC), acid volatile sulfide (AVS), and clay have great influence on the distribution of THg in sediment. Methylmercury in the estuary sediment was positively correlated with THg, AVS, TOC, and clay, while these relationships were not revealed in the lake sediment. Cluster and principal component analysis results showed that THg, clay, and TOC were derived from the same sources in the sediment of Nansi Lake. It implied that for improving the water environmental quality of lakes, the environmental management of rivers entering the lake should be strengthened. [ABSTRACT FROM AUTHOR]

Zooplankton community could be affected by aquatic environment, land use patterns, and climate factors. However, few studies have evaluated the relative importance of these factors to the zooplankton community succession on a long-term scale. In this study, long-term data were used to analyze the succession characteristics and drivers of zooplankton communities in Honghu Lake, a large-scale shallow lake in central China. Results showed that zooplankton community structure changed greatly in 1959–2021. In general, the species number decreased, abundance and biomass increased, and the number and proportion of pollution tolerant species among dominant species increased during the past ~ 60 years. For the driving factors of zooplankton from 1992 to 2021, redundancy analysis showed that nutrients, wind speed, and aquaculture enclosure and pond were the main drivers of Protozoa and Rotifera, while phytoplankton abundance, wind speed, dissolved oxygen, and farmland were the main drivers of Cladocera and Copepoda. Generalized additive model showed that the aquatic environment had the highest direct explanation (mean is 60.2%) to zooplankton variation, followed by land use (mean is 35.6%) and climate factors (mean is 33.1%). Variance partitioning analysis showed that the effects of human activities (32.9–43.1%) associated with land use, water quality, and phytoplankton on the zooplankton succession are stronger than that of climate factors (19.9–29.2%). Additionally, lake eutrophication is an important factor for the decline in the richness index (p = 0.0017, r = − 0.8411) and Shannon index (p = 0.0301, r = − 0.8020) of zooplankton from 2019 to 2021. Our results highlighted that anthropogenic activity has stronger driving effects on zooplankton succession in the long term than climate changes in the lake. These findings can provide insights into zooplankton conservation in response to global climate change and complex anthropogenic actions. [ABSTRACT FROM AUTHOR]

• This study encompasses 841 sampling records from 217 chinese lakes. • The trophic state of lakes was significantly related to the degree of human impact. • Human impact disrupted most relationships among environmental factors of the lakes. • Correlations between salinity and organic C/N were apparent in saline lake regions. • Human impact and environmental factor network can be indicators of lake status. Anthropogenic and natural disturbance to inland aquatic ecosystems displays a notable spatial difference, yet data to measure these differences are scarce. This study encompasses 217 lakes distributed over five lake regions of China and elucidates the environmental factors determining the spatial variability of the water quality and trophic status. A significant correlation between human modification index in surrounding terrestrial systems (HMT) and trophic status of lake ecosystems (TSI) was found, and the regression slope in each region was similar except in the Qinghai-Tibet Plateau region. It was further noted that the pattern of environmental factor network (EF network) differed among freshwater and saline lakes. The EF network was complex for freshwater lakes in less human-influenced areas, but intensive man-made influence disrupted most relationships except for those between total nitrogen, total phosphorus, chlorophyll- a , and water turbidity. As for regions including saline lakes, correlations among water salinity and organic forms of carbon and nitrogen were apparent. Our results suggest that HMT and EF network can be useful indicators of the ecological integrity of local lake ecosystems, and integrating spatial information on a large scale provides conservation planners the option for evaluating the potential risk on inland aquatic systems. [ABSTRACT FROM AUTHOR]

Elucidating the mechanism of formation of biota on islands will contribute to our understanding of the evolutionary mechanisms that generate biodiversity. In this study, we focus on the evolutionary history of Ephemera orientalis , which is distributed in East Asia. Phylogenetic analyses were performed using the mitochondrial DNA 16S rRNA, cytochrome oxidase subunit I and the nuclear DNA histone H3 regions. We found that these mayflies exhibit genetic differentiation between the Japanese and Korean populations. The Tsushima population, which is located between the Japanese Islands and the Korean Peninsula, was positioned genetically as a continental clade. The populations of the Fuji-Goko Lakes and Lake Ashino-ko in Central Japan were genetically differentiated from the other populations. The genetic structures over a wide area of the Japanese Islands were confirmed and a loose genetic regionality was observed, which was thought to result from secondary contact of the north-eastern and south-western lineages after their long separation by a geohistorical division event. We have gathered important knowledge regarding the evolutionary history of organisms on islands and investigated the colonization and isolation of biological populations within a species with high dispersal ability. [ABSTRACT FROM AUTHOR]

A cascading rainfall–landslide–tsunami event occurred on June 29th, 2022, in Todos los Santos Lake, located in southern Chile, affecting the tourist town of Petrohué. The event took place after several days of heavy rain during an extratropical cyclone. Important data were collected during a field survey, including hillslope 3D scans, lake–river bathymetry, orthomosaic photos, and an assessment of damage to public infrastructure. The analysis showed that the landslide had an estimated length, width, and depth of 175 m, 40 m, and 1.5 m, respectively, which resulted in a total volume of 10,500 m3. The underwater runout distance of the landslide was estimated at 40 m, with a final water depth of 12 m. The initial tsunami wave was observed to be ~1 m, and since the distance from the landslide to the town was ~500 m, an arrival time of ~1 min was observed. Despite the small tsunami amplitudes, the pedestrian bridge of the floating pontoon collapsed due to the flow current and vertical oscillations. The results of the numerical simulation of the tsunami supported the observed data. They showed that the impact of the tsunami was only in the near field and was influenced by the bathymetry, such that refraction and edge waves were observed. The landslide occurred in an area where previous debris flows took place in 2013 and 2015. The main finding of the present research is that the occurrences of this and previous landslides were controlled by the presence of the Liquiñe–Ofqui fault zone, which generates broad areas of structural damage, with mechanical and chemical weathering significantly reducing rock strength. These observations provide a warning regarding the susceptibility of similar regions to other trigger events such as earthquakes and rainfall. This recent landslide highlights the need for a more comprehensive hazard assessment, for which probabilistic analysis could be focused on large active strike-slip fault systems. It also highlights the importance of community awareness, particularly in areas where tourism and real estate speculation have significantly increased urban development. [ABSTRACT FROM AUTHOR]

The 4% of the Argentinian sector from Tierra del Fuego is covered with water. Colored lakes are among the most conspicuous water bodies in the Andean area, and Laguna Negra, in the National Park Tierra del Fuego, is one of them. The main physical and chemical variables were monitored and phytoplankton samples were obtained with a monthly frequency during the ice-free period, between September 2016 and March 2018 (n=15). Laguna Negra was deeper than expected, with a maximum depth of 15.5 m. In addition, this lake has high pH values (7.5±0.55), which were quite stable during the study (variation coefficient, VC=8.3%). These characteristics preclude us from considering this lake as a shallow peatland lake. Dissolved and total nutrients were low and did not show a temporal pattern of fluctuation during the study period. The same trend of no clear fluctuation was also shared by dissolved organic carbon concentration (DOC=7.7±0.78 mg/L). Taxa richness ranged between 6 and 13 throughout the study. The biovolume was inversely correlated with the vertical attenuation coefficient of light (Kd). Phytoplankton biomass (chlorophyll-a concentration, abundance, and biovolume) was generally low, with Dinobryon divergens, Mallomonas sp. and Parvodinium cf. inconspicuum being the dominant taxa. Depending on the classification used, Laguna Negra might be regarded as a humic or dystrophic lake because its color is at the edge of values used in the current literature to consider a lake as humic. [ABSTRACT FROM AUTHOR]

The world's largest lakes, including the Laurentian Great Lakes, have experienced significant surface warming and loss of ice cover over the last several decades. Although changing surface conditions have received substantial research interest, changes below the surface remain largely unexplored, despite their importance for turbulent mixing, nutrient cycling, and primary production. In this study, we investigate changes in subsurface thermal structure and timing in Lake Michigan-Huron related to ongoing climate warming. This work utilizes atmospheric reanalysis data to drive the Great Lakes Finite Volume Community Ocean Model (GL-FVCOM), providing three-dimensional hydrodynamic and ice simulations between 1979 and 2021. Results are used to analyze trends in ice and temperature dynamics, revealing significant changes in annually averaged ice cover (− 2.1– − 5.2%/decade), ice thickness (− 0.68 – − 2.0 cm/decade), surface temperature (+ 0.47– + 0.51 ∘ C /decade), and bottom temperature (+ 0.26– + 0.29 ∘ C /decade) over the last 40 years, especially in ecologically important bays (e.g., Green Bay, Saginaw Bay). Significant warming was observed at all depth layers (0–270 m), with warming trends in the epilimnion and hypolimnion that agreed well with recent analysis of observational data in Lake Michigan. Shifting stratification dynamics led to dramatic changes in modelled overturning behavior, and earlier spring turnover dates (− 2.2– − 7.5 days/decade) and later fall turnover dates (+ 2.5– + 6.3 days/decade) led to a net lengthening of the stratified period. This study presents one of the most comprehensive analyses of changes in Great Lakes subsurface temperatures to date, providing important context for future climate modelling and coastal management efforts in the region. [ABSTRACT FROM AUTHOR]

We estimated chlorophyll-a (Chl-a) concentration using various combinations of routine sampling, automatic station measurements, and MERIS satellite images. Our study site was the northern part of the large, shallow, mesotrophic Lake Pyhäjärvi located in southwestern Finland. Various combinations of measurements were interpolated spatiotemporally using a data fusion system (DFS) based on an ensemble Kalman filter and smoother algorithms. The estimated concentrations together with corresponding 68% confidence intervals are presented as time series at routine sampling and automated stations, as maps and as mean values over the EU Water Framework Directive monitoring period, to evaluate the efficiency of various monitoring methods. The mean Chl-a calculated with DFS in June–September was 6.5–7.5 µg/l, depending on the observations used as input. At the routine monitoring station where grab samples were used, the average uncertainty (standard deviation, SD) decreased from 2.7 to 1.6 µg/l when EO data were also included in the estimation. At the automatic station, located 0.9 km from the routine monitoring site, the SD was 0.7 µg/l. The SD of spatial mean concentration decreased from 6.7 to 2.9 µg/l when satellite observations were included in June–September, in addition to in situ monitoring data. This demonstrates the high value of the information derived from satellite observations. The conclusion is that the confidence of Chl-a monitoring could be increased by deploying spatially extensive measurements in the form of satellite imaging or transects conducted with flow-through sensors installed on a boat and spatiotemporal interpolation of the multisource data. [ABSTRACT FROM AUTHOR]

As an emerging pollutant, microplastics have attracted widespread concern around the world. Research on microplastics was first conducted in oceans, and in recent years, inland water, especially lakes, has gradually become a hot spot. This paper systematically reviews the sampling, separation, purification, and identification technologies used to assess microplastics in lakes and summarizes the occurrence of lake microplastics worldwide. The results show that microplastics are widespread in lake water and sediment. There are obvious geographical differences in the occurrence of microplastics. The abundance of microplastics in different lakes varies greatly. The forms are mostly fibrous and fragments, and the main polymers are polypropylene (PP) and polyethylene (PE). Previous papers have failed to comment in as much detail on the microplastic sampling techniques employed within lake systems. The sampling and analysis methods are critical to accurately evaluating contamination results. Due to the widespread presence of microplastics and the lack of uniform standards, there are various sampling methods. Trawls and grabs are most widely used in the sampling of lake water bodies and sediment, and sodium chloride and hydrogen peroxide are the most widely used media for flotation and digestion, respectively. In the future, it will be critical to establish unified standards for lake microplastic sampling and analysis technology, further explore the migration mechanism of microplastics in lake systems, and pay attention to the impact of microplastics on lake ecosystems. [ABSTRACT FROM AUTHOR]

Degradation of lake ecosystem is a common problem existing in many countries. Remediation of degraded lake is urgently needed in order to maintain water safety and lake ecosystem health. Restoration of submerged macrophyte is considered as an important measure of ecological remediation of shallow lakes after pollution loading get effectively controlled. Nowadays, enclosures resembling those used in aquaculture historically are widely used for submerged macrophyte restoration. Although submerged macrophyte can be successfully restored in enclosure, it's contribution to the whole lake ecological remediation is limited. Fish manipulation, which reduces fish stock and adjusts fish community structure, was found able to improve water quality and promote submerged macrophyte restoration in many lakes. However, the role of fish in ecological restoration do not receive enough attention in many ecological remediation projects. Future studies are required to better understand the role of fish in lake nutrient cycle and the influence on submerged macrophyte to help develop theory that better guide the fish manipulation for the ecological remediation in shallow lakes. In the end, we want to point out that manipulation of fish community structure following by natural restoration and/or artificial planting of submerged macrophyte could be an effective strategy for whole lake ecological remediation of shallow lakes, and suggest that fish manipulation measure should be tested in more ecological remediation projects of shallow lakes worldwide. [ABSTRACT FROM AUTHOR]

The spatial and seasonal distribution of heterotrophic bacterioplankton has been studied in Lake Pleshcheyevo. Over the past 30 years, the abundance of microorganisms has increased threefold. The maximum values have been recorded at littoral stations. The main part of bacterial production is also produced there. Trophic levels have increased, but the ecosystem of the lake withstands the increased load. [ABSTRACT FROM AUTHOR]

Marble is the most important natural material because of its structural features and its long durability. It is mined at operated quarries on hill slopes. The original landform is permanently altered, and vegetation cover is destroyed. Another important feature of marble quarries is the large amount of waste materials released during the quarrying process. In the last decades, together with the visible effects of global warming and climate change, fresh water resources are rapidly depleted and polluted due to careless land use. Quarrying operations are among the most important stakeholders of this process. Environmental effects of quarry activities depend on the location of the site in the landscape, the vertical and horizontal dimensions of the excavation, the methods used to excavate the marble, and the formation of the geological structure. Furthermore, the region's seismicity, microclimate conditions, ecological condition, and surface and groundwater conditions are all factors influencing environmental degradation. Additionally, numerous serious environmental impacts associated with quarrying activities near the site, such as visual pollution, water, dust, noise, air pollution, vibration, land subsidence, and landslides, will cause health issues and unpredictable biodiversity loss. Quarrying operations have the potential to impact pre-existing ecosystems, including groundwater depletion, loss of fertile topsoil, forest degradation, and human health. This article aims to draw attention to various serious environmental impacts, health problems and biodiversity loss resulting from quarrying operations in Burdur Lake Basin. [ABSTRACT FROM AUTHOR]

Freshwater exposure is associated with a diverse range of infections from pathogens present in soil and water. This includes skin and soft tissue infections and wound infections, gastrointestinal infections, and central nervous system infections acquired through recreational exposure or trauma. Case reports of freshwater-associated infections typically focus on waterborne pathogens as the cause of illness; however, patients who experience significant physical trauma during freshwater exposure may also be at increased risk for infection with their own flora if the nature of the injury allows entry of bacteria through a mechanism such as mucosal injury. Here, we present a case of a healthy 18-year-old man who rapidly developed bacteremia with oral flora following several falls submerging his face into lake water while water skiing, as well as acute polymicrobial sinusitis and subsequent pre-septal cellulitis. Shortly after his water skiing falls, the patient developed sinusitis that rapidly progressed to headaches, emesis, and significant periorbital swelling. Blood cultures grew Prevotella salivae, a bacterium naturally found in the oral cavity. Sinus cultures grew Klebsiella aerogenes and Listeria monocytogenes, which may be associated with lake water. The infection improved with antibiotic therapy, and the patient was discharged on a regimen of amoxicillin/clavulanic acid and trimethoprim-sulfamethoxazole. Reports of bacteremia with oral flora following freshwater injury are not typically reported, and to our knowledge, this is the first report describing bacteremia with P salivae. [ABSTRACT FROM AUTHOR]

Lakes (including artificial reservoirs) are important surface water resources, and they are also an important part of the earth surface system consisting of "mountains, waters, forests, fields, lakes, grassland and desert". Based on the lake survey data and long-term monitoring data collected by the Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences as well as other institutions, this paper systematically analyzed the overall status and long-term trends of the ecological and environmental changes of natural and artificial lakes in China, focused on the ecological and environmental status and changes of typical lakes in the five major lake zones in China and highlighted the protection effects and challenges facing the ecological environment of lakes in China. In the meantime, countermeasures and suggestions for policy-makers and are proposed to promote the protection and restoration of the ecology and environment of lakes in China, and to ensure the water safety and sustainable development of lakes and river basins. [ABSTRACT FROM AUTHOR]

Anguillid eels are near globally distributed catadromous fishes with marine spawning areas and inshore and inland growth areas in both lotic (rivers, estuaries) and lentic (lakes, ponds, lagoons) water bodies. As predators, anguillid eels play an important ecological role in both marine and freshwater systems, and several species are harvested commercially for food. However, some of the more widely distributed species have undergone severe declines in recruitment and their population status is now of significant concern. Given the multiple and lengthy migrations undertaken by anguillid eels, understanding of the drivers of movement is fundamental for species conservation and management. Yet, despite the importance of lentic systems to their ecology, most studies on anguillid eel movement have been conducted in lotic systems. Given that key influences on eel migration in lotic water bodies, such as fluctuations in flow and water temperature, may be minimised in lentic environments, the transferability of findings between lotic and lentic systems cannot be assumed. A systematic map was constructed to synthesise current knowledge on the extrinsic and intrinsic drivers of anguillid eel movement in lentic systems. The current state of knowledge of the drivers of eel movement in lentic systems is presented and compared to the relatively well-understood drivers of movement in lotic systems. We also discuss current knowledge gaps and limitations, and identify key future research requirements to inform the management and conservation of anguillid eels in understudied lentic systems. [ABSTRACT FROM AUTHOR]

Lake deltas (LDs) receive nutrient and energy subsidies from upstream habitats. These inputs can support LD benthic production. However, LDs may also receive impacts from upstream disturbance. Small lakes in coastal British Columbia often have inflow streams from areas with forest harvesting, which is pervasive in this region. Forest harvesting impacts can alter stream production, although downstream impacts on lakes, compared to streams, are less studied and understood. We aimed to test whether benthic LD communities (biofilm and invertebrates) are more productive and (or) diverse compared to other communities along the lakeshore (LS) (non-LDs), and whether there are differences in LD communities associated with upstream harvesting. We compared LD communities with upstream riparian areas that were harvested (HLD) or relatively undisturbed (ULD), and LS sites. We found that while community structure was similar across sites, ULDs had higher biofilm and invertebrate standing stocks (1.5- and 2-times higher, respectively) than HLDs and LS sites. Our results suggest subsidies and benthic production were higher at ULDs. These results advance our understanding of forest harvesting disturbance and stream-lake connectivity. [ABSTRACT FROM AUTHOR]

Compared with the river ecosystem, the lake ecosystem has poor fluidity, relatively low oxygen content and is more vulnerable to be polluted. Qinghai Lake is an important ecological protection barrier in the Qinghai-Tibet Plateau of China, which is closely related to the local ecosystem. The current method has poor ability to analyze the impact of seasonal changes, resulting in low reliability of the results. Therefore, this paper taken Qinghai Lake as an example, summarized the ecological status and seasonal characteristics, and established an method used for evaluating the ecohydrology evolution process in lake area under seasonal variation. According to the analysis results, Kendall rank correlation test was used to calculate the hydrological correlation coefficient. The ecohydrology model was constructed and combined with hydrological correlation coefficient and local climate conditions to complete the analysis of ecohydrology evolution process in Qinghai Lake area. Through comparison, it can be seen that the accuracy of the proposed method can reach up to 90%, the time-consuming is short, the reliability is high, and the maximum can reach 98.8%. The experimental results show that the method has lower operation cost and higher data analysis ability, which has a certain application prospect. [ABSTRACT FROM AUTHOR]

For decades, diatoms have been recognized as powerful bio-indicators of modern water quality. They have also been utilized in the design of transfer functions, which can be applied to diatom assemblages in lake sediment cores to infer aspects of past lake hydrochemistry and estimate variables that can be incorporated into paleohydrology models. The Ounianga lakes, in the heart of the Chadian Sahara, possess unique and well-preserved sediment records that extend back beyond the middle Holocene. Today, the lakes display a range of hydrochemical conditions, from fresh to hypersaline. Mainly fed by fossil groundwater that originates in the Nubian Sandstone Aquifer System, measured conductivity across these lakes varies from 217 to 352,000 µS cm−1, values that are influenced by factors such as hydrology, local geomorphology (e.g., depth and area), and aquatic vegetation. Although these lakes have been on the UNESCO World Heritage List since 2012, they have never been studied in detail because they are located on the fringes of the Chadian Sahara. The distribution of diatom taxa in the lakes today is closely linked to water-column physical and chemical conditions, especially conductivity. Whereas each lake has particular features that influence its diatom flora, diatoms across a conductivity gradient enabled identification of three distinct waterbody types, freshwater lakes, meso-saline to hyper-saline lakes, and freshwater springs. Relationships between diatom species distributions and environmental variables were examined using multivariate analysis, which revealed that conductivity is the variable that explains most of the variance in the diatom flora. We used modern diatom assemblages from the lakes to develop a predictive model (transfer function) for conductivity, using the weighted averaging method. Our conductivity prediction model is strong, with a coefficient of determination (R2) of 0.89 between estimated and measured values, and a value of 0.78 using jackknife estimates of prediction. This study better constrained conductivity optima and tolerance values for diatom species found in the Ounianga lakes, thereby enabling development of a model that will yield better inferences for past conductivity, using diatoms from lake sediment records in the region. [ABSTRACT FROM AUTHOR]

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Abstract Mean annual air temperature has been increasing in Alaska since the 1970s and is expected to continue to increase through the current century, resulting in significant environmental changes (e.g., permafrost thaw, shifts in vegetation community composition and distribution, increased wildfire frequency and severity). Because there is little long‐term monitoring data available on lake ecosystems in the subarctic it is difficult to predict how lakes will respond. Here we present data from an ~20‐year long‐term lake and climate monitoring program in Interior Alaska. A significant portion of the lake catchment was burned by wildfires in 1986 and again in 2004. As a result, much of the vegetation in the lake catchment was converted from spruce‐dominated forest to deciduous forest, indicating likely permafrost degradation. At a nearby monitoring site absent of fire effects, mean annual ground temperatures at 50 and 90 cm warmed significantly from about −2°C to about −1°C over the 20‐year monitoring period. Warming of similar or greater magnitude is inferred at the study site due to fire effects. Lake water analyses before and after the 2004 fire show a significant postfire increase in dissolved organic carbon, total nitrogen, and total phosphorous that persisted for a short period (~3 years) and was followed by small, but significant, increases in specific conductance and ion concentrations. Approximately 15 years postfire sulfate and cation concentrations in the lake increased exponentially due to the development of a groundwater seep near the lake. The seep likely formed as a result of permafrost thaw creating new subsurface flowpaths in response to long‐term climate warming and fire effects. In 2021, specific conductance and sulfate concentrations reached 657 μS/cm and 71 mg/L respectively, exceeding tolerance thresholds of the water lily Nuphar lutea. In 2021, N. lutea beds that had occupied the lake since 1981 were no longer visible. Depending on local catchment characteristics, source waters and flow paths contributing to small subarctic lakes will continue to evolve uniquely in response to climate change and thawing permafrost. This case study shows the cascading effects of warming soil and wildfires on catchment characteristics as well as terrestrial and aquatic vegetation and lake water chemistry.

The Ebolowa Municipal Lake (EML) (South Cameroon) in order to identify the early diagenesis processes taking place in the lake and the factors influencing them. To this end, 21 samples were collected. In situ, hydrogen potential, redox potential, conductivity, dissolved oxygen content, and turbidity were measured. In the laboratory, the samples were subjected to mineralogical analysis by X-ray diffraction, geochemical analysis by X-ray fluorescence and ICP-MS, and statistical analysis. The coefficient of variation (Qi) was calculated from the geochemical data. In the water column, OD > 2 mg/L, pH > 7 and Eh 1 for Al, Fe, Mn, Mg, K, Na, P, Ni, Co, Zn, Pb, Cd, Cu, Ba, and V, and Qi

Abstract The effects of dams on carbon dioxide (CO2) fluxes in downstream lakes remain elusive. Here we combined eddy covariance observations and random forest models to examine multi‐decadal variations in CO2 fluxes in the Poyang Lake, the largest freshwater lake in China, and quantified the contribution of the Three Gorges Dam (TGD), the world's largest hydraulic project. We found the lake fluctuated between CO2 source and sink in 1961–2016, and tended to be CO2 sink in the post‐TGD period (2003–2016) when vegetation expanded early and spatially due to declining water level. TGD can explain approximately 6% of the total differences in annual CO2 fluxes, with major contributions in the impoundment period (up to 22% in middle September to October). The results show a positive side of operational major hydraulic projects on lake carbon sink, and probably caution the negative side of carbon release after dam removal.

In this study, we employ in situ, meteorological, and remote sensing data to estimate chlorophyll-a concentration at different depths in a South American freshwater ecosystem, focusing specifically on a lake in southern Chile known as Lake Maihue. For our analysis, we explored four different scenarios using three deep learning and traditional statistical models. These scenarios involved using field data (Scenario 1), meteorological variables (Scenario 2), and satellite data (Scenarios 3.1 and 3.2) to predict chlorophyll-a levels in Lake Maihue at three different depths (0, 15, and 30 m). Our choice of models included SARIMAX, DGLM, and LSTM, all of which showed promising statistical performance in predicting chlorophyll-a concentrations in this lake. Validation metrics for these models indicated their effectiveness in predicting chlorophyll levels, which serve as valuable indicators of the presence of algae in the water body. The coefficient of determination values ranged from 0.30 to 0.98, with the DGLM model showing the most favorable statistics in all scenarios tested. It is worth noting that the LSTM model yielded comparatively lower metrics, mainly due to the limitations of the available training data. The models employed, which use traditional statistical and machine learning models and meteorological and remote sensing data, have great potential for application in lakes in Chile and the rest of the world with similar characteristics. In addition, these results constitute a fundamental resource for decision-makers involved in the protection and conservation of water resource quality.

Extraction of lake water bodies from remote sensing images provides reliable data support for water resource management, environmental protection, natural disaster early warning, and scientific research, and helps to promote sustainable development, protect the ecological environment and human health. With reference to the classical encoding-decoding semantic segmentation network, we propose the network model R50A3-LWBENet for lake water body extraction from remote sensing images based on ResNet50 and three attention mechanisms. R50A3-LWBENet model uses ResNet50 for feature extraction, also known as encoding, and squeeze and excitation (SE) block is added to the residual module, which highlights the deeper features of the water body part of the feature map during the down-sampling process, and also takes into account the importance of the feature map channels, which can better capture the multiscale relationship between pixels. After the feature extraction is completed, the convolutional block attention module (CBAM) is added to give the model a global adaptive perception capability and pay more attention to the water body part of the image. The feature map is up-sampled using bilinear interpolation, and the features at different levels are fused, a process also known as decoding, to finalize the extraction of the lake water body. Compared with U-Net, AU-Net, RU-Net, ARU-Net, SER34AUNet, and MU-Net, the R50A3-LWBENet model has the fastest convergence speed and the highest MIoU accuracy with a value of 97.6%, which is able to better combine global and local information, refine the edge contours of the lake’s water body, and have stronger feature extraction capability and segmentation performance.

Lakes are an important component of global water resources. In order to achieve accurate lake extractions on a large scale, this study takes the Tibetan Plateau as the study area and proposes an Automated Lake Extraction Workflow (ALEW) based on the Google Earth Engine (GEE) and deep learning in response to the problems of a low lake identification accuracy and low efficiency in complex situations. It involves pre-processing massive images and creating a database of examples of lake extraction on the Tibetan Plateau. A lightweight convolutional neural network named LiteConvNet is constructed that makes it possible to obtain spatial–spectral features for accurate extractions while using less computational resources. We execute model training and online predictions using the Google Cloud platform, which leads to the rapid extraction of lakes over the whole Tibetan Plateau. We assess LiteConvNet, along with thresholding, traditional machine learning, and various open-source classification products, through both visual interpretation and quantitative analysis. The results demonstrate that the LiteConvNet model may greatly enhance the precision of lake extraction in intricate settings, achieving an overall accuracy of 97.44%. The method presented in this paper demonstrates promising capabilities in extracting lake information on a large scale, offering practical benefits for the remote sensing monitoring and management of water resources in cloudy and climate-differentiated regions.

Reservoirs of ^14 C-depleted methane (CH _4 ), a potent greenhouse gas, residing beneath permafrost are vulnerable to escape where permafrost thaw creates open-talik conduits. However, little is known about the magnitude and variability of this methane source or its response to climate change. Remote-sensing detection of large gas seeps would be useful for establishing a baseline understanding of sub-permafrost methane seepage, as well as for monitoring these seeps over time. Here we explored synthetic aperture radar’s (SAR) response to large sub-permafrost gas seeps in an interior Alaskan lake. In SAR scenes from 1992 to 2011, we observed high perennial SAR L-band backscatter ( σ ^0 ) from a ∼90 m-wide feature in the winter ice of interior Alaska’s North Blair Lake (NBL). Spring and fall optical imagery showed holes in the ice at the same location as the SAR anomaly. Through field work we (1) confirmed gas bubbling at this location from a large pockmark in the lakebed, (2) measured flux at the location of densest bubbles (1713 ± 290 mg CH _4 m ^−2 d ^−1 ), and (3) determined the bubbles’ methane mixing ratio (6.6%), radiocarbon age (18 470 ± 50 years BP), and δ ^13 C _CH4 values (−44.5 ± 0.1‰), which together may represent a mixture of sources and processes. We performed a first order comparison of SAR σ ^0 from the NBL seep and other known sub-permafrost methane seeps with diverse ice/water interface shapes in order to evaluate the variability of SAR signals from a variety of seep types. Results from single-polarized intensity and polarimetric L-band SAR decompositions as well as dual-polarized C-band SAR are presented with the aim to find the optimal SAR imaging parameters to detect large methane seeps in frozen lakes. Our study indicates the potential for SAR remote sensing to be used to detect and monitor large, sub-permafrost gas seeps in Arctic and sub-Arctic lakes.

Lakes are essentially interlinked to humans as they provide water for drinking, agriculture, industrial and domestic purposes. The upsurge of plastic usage, its persistence, and potential detrimental effects on organisms cause impacts on the trophic food web of freshwater ecosystems; this issue, however, still needs to be explored. Zooplankton worldwide is commonly studied as an indicator of environmental risk in aquatic ecosystems for several pollutants. The aim of the review is to link the existing knowledge of microplastic pollution in zooplankton to assess the potential risks linked to these organisms which are at the first level of the lacustrine trophic web. A database search was conducted through the main databases to gather the relevant literature over the course of time. The sensitivity of zooplankton organisms is evident from laboratory studies, whereas several knowledge gaps exist in the understanding of mechanisms causing toxicity. This review also highlights insufficient data on field studies hampering the understanding of the pollution extent in lakes, as well as unclear trends on ecosystem–level cascading effects of microplastics (MPs) and mechanisms of toxicity (especially in combination with other pollutants). Therefore, this review provides insight into understanding the overlooked issues of microplastic in lake ecosystems to gain an accurate ecological risk assessment.