Plateau Lake Research Articles

Environmental impacts and nitrogen-carbon-energy nexus of vegetable production in subtropical plateau lake basins

Vegetables are important economic crops globally, and their production has approximately doubled over the past 20 years. Globally, vegetables account for 13% of the harvested area but consume 25% of the fertilizer, leading to serious environmental impacts. However, the quantitative evaluation of vegetable production systems in subtropical plateau lake basins and the establishment of optimal management practices to further reduce environmental risks are still lacking. Using the life cycle assessment method, this study quantified the global warming, eutrophication, acidification, and energy depletion potential of vegetable production in a subtropical plateau lake basin in China based on data from 183 farmer surveys. Our results indicated that vegetable production in the study area, the Erhai Lake Basin, was high but came at a high environmental cost, mainly due to low fertilizer efficiency and high nutrient loss. Root vegetables have relatively high environmental costs due to the significant environmental impacts of fertilizer production, transportation, and application. A comprehensive analysis showed that the vegetable production in this region exhibited low economic and net ecosystem economic benefits, with ranges of 7.88–8.91 × 103 and 7.35–8.69 × 103 $ ha−1, respectively. Scenario analysis showed that adopting strategies that comprehensively consider soil, crop, and nutrient conditions for vegetable production can reduce environmental costs (with reductions in global warming potential (GWP), eutrophication potential (EP), acidification potential (AP), and energy depletion potential (EDP) by 10.6–28.2%, 65.1–73.5%, 64.5–71.9%, 47.8–70.4%, respectively) compared with the current practices of farmers. This study highlighted the importance of optimizing nutrient management in vegetable production based on farmers’ practices, which can achieve more yield with less environmental impacts and thereby avoid the “trade-off” effect between productivity and environmental sustainability.

Exploring the scale effect of nonpoint source pollution risk on water quality in Lake Basins of Central Yunnan Plateau using the Minimum Cumulative Resistance model.

Nonpoint source (NPS) pollution has emerged as the predominant water environment issue confronting plateau lakes in central Yunnan. Quantitative analysis of the impact of NPS pollution on water quality constitutes the key to preventing and controlling water pollution. However, currently, there is a dearth of research on identifying NPS pollution risks and exploring their relationship with water quality based on the Minimum Cumulative Resistance (MCR) model in the plateau lake basins of central Yunnan. Particularly, studies on the spatial heterogeneity of the impact of NPS pollution on water quality from a multi-scale perspective are scarce. Therefore, this study focuses on three typical lake basins in the Central Yunnan Plateau-Fuxian Lake, Xingyun Lake, and Qilu Lake (the Three Lakes). Utilizing the MCR model to identify NPS pollution risks, the study analyzes seven different scales, including sub-basins, riparian buffer zones (100 m, 300 m, 500 m, 700 m, and 1,000m) and lakeshore zones, to reveal the multi-scale effects of NPS pollution on water quality through correlation analysis. The results indicate that: (1) Over 60% of the areas in the Three Lakes Basin are at high or extremely high risk, mainly concentrated in flat terrain and around inflow rivers; (2) The area of NPS pollution from paddy field source landscape (PFSL) is greater than that from construction land source landscape (CLSL), and the high-risk areas of NPS pollution are also larger for PFSL compared to CLSL; (3) The mean resistance values of PFSL and CLSL show a significant negative correlation with monthly mean values of water quality indexes (NH3-N, TP, CODCr), with the 1,000 m riparian buffer zone scale showing the greatest correlation with most water quality indexes, especially NH3-N; (4) The correlation between the mean resistance value of CLSL and the monthly mean values of water quality indexes is significantly higher than that of PFSL, indicating a greater impact of CLSL on water quality compared to PFSL. In summary, PFSL and CLSL are the primary sources of NPS pollution in the Three Lakes Basins. The 1,000 m riparian buffer zone scale is the most sensitive to the impact of NPS pollution on water quality. This study provides scientific references for landscape pattern optimization and precise control of NPS pollution risks in the Central Yunnan Plateau lake basins and offers a new research perspective for exploring multi-scale effects of NPS pollution on water quality.

Brachysporium sinense, a new species from a plateau lake in Yunnan Province, China

Yunnan is one of the fungal diversity hotspots and many studies of lignicolous freshwater fungal research have been done in this Province. Presently, research on lignicolous freshwater fungi in the plateau lakes of this region is being systematically conducted. During our investigation of the species diversity of lignicolous freshwater fungi in Dujuanhu Lake, we found a distinctive species, Brachysporium sinense, based on morphological characteristics and phylogenetic analysis. Brachysporium sinense is distinguished from other Brachysporium species by monoblastic, integrated, terminal conidiogenous cells and fusoid to limoniform, verrucose, septate, brown to dark brown conidia with subhyaline ends, which are connected to the conidiogenous cells by a single denticle. Detailed descriptions and illustrations and relatively comprehensive sequence data are provided.

Differences in Nitrogen Sources and Contributions in Shallow Groundwater in Plateau Lake Area with Different Climate Types

Clarifying the concentration, major sources, and contribution differences of nitrogen in shallow groundwater in plateau lake areas with different climate types can provide a novel direction for the control of nitrate （NO3-） pollution in regional groundwater. Taking the shallow groundwater around Erhai Lake in the subtropical monsoon climate zone and Chenghai Lake in the dry-hot valley area of the Jinsha River as the research objects, using hydrochemical indexes and multi-isotope techniques （δ15N-NO3-, δ18O-NO3-, δ18O-H2O, and δ2H-H2O） combined with the stable isotope （SIAR） model； the differences in nitrogen concentration in shallow groundwater around Erhai Lake and Chenghai Lake were analyzed, the sources of NO3- were identified, and the contribution rates of each pollution source were calculated. The results showed that water quality of more than 33% and 5% of shallow groundwater sampling points around Erhai Lake and Chenghai Lake was worse than the groundwater Class Ⅲ quality requirements （GB/T 14848） of 20 mg·L-1 for nitrate nitrogen （NO3--N）, respectively. The δ18O-H2O and δ2H-H2O in shallow groundwater around Erhai Lake and Chenghai Lake were parallel to the global and Chinese atmospheric precipitation lines, and a large intercept was present, indicating that atmospheric precipitation was not the major recharge source of groundwater in the two regions. The contribution rate of different NO3- sources in shallow groundwater around Erhai Lake was the highest for soil organic nitrogen （53.77%）, followed by nitrogen fertilizer （21.75%） and manure and sewage （21.55%）, and atmospheric deposition nitrogen （2.93%） was the lowest. Denitrification occurred in the transformation process of nitrogen in groundwater. The contribution rate of different NO3- sources in shallow groundwater around Chenghai Lake was manure and sewage （44.88%） > soil organic nitrogen （37.03%） > nitrogen fertilizer （16.17%） > atmospheric deposition nitrogen （1.92%）, and nitrification occurred in the transformation process of nitrogen in groundwater. The climate type significantly affected the shallow groundwater level, altering the migration and transformation process of nitrogen, thereby affecting the nitrogen concentration in groundwater and the contribution of NO3- as the chief source. However, the major source of NO3- was not affected by the climate type； however was more affected by land use, agricultural activities, and manure treatment methods.

Environmental Factors Shaping the Culturable Freshwater Fungi Diversity of Four Lakes in Yunnan Province, China

Our study focused on freshwater fungal diversity, an important aspect in assessing the ecology of aquatic ecosystems. We carefully explored the diversity and influencing factors of culturable fungi across Dianchi Lake, Fuxian Lake, Xingyun Lake, and Yangzonghai Lake in Yunnan Province, China. Through fungi culture, morphological characterization, and ITS sequence analysis, we identified a total of 565 isolates belonging to 405 species across 133 genera. The diversity indices viz. H′, D, and J were evaluated for fungal diversity across the lakes. Interestingly, although diversity indices were highest during summer and at Yangzonghai Lake, no significant differences in fungal community diversity were observed between seasons and regions. Water variables were analyzed and indicated that changes with rapid fluctuations in temperature, pH, and dissolved oxygen likely influence fungal diversity. These findings significantly contribute to our understanding of fungal communities within plateau lake ecosystems, thereby aiding in managing and conserving vital aquatic resources.

Towards the development of a ‘land-river-lake’ two-stage deep learning model for water quality prediction and its application in a large plateau lake

Accurate prediction of water quality that is essential for effective lake management requires a comprehensive understanding of influential factors in the ’land-river-lake’ continuum. We develop a novel deep learning model employing a Long Short-Term Memory (LSTM) model for predicting water quality, and apply it for a large plateau lake, Lake Dianchi. The model comprises two stages: the first establishes a correlation between land and rivers by predicting nutrient loads, incorporating socioeconomic and meteorological features. The second establishes a correlation between feeding rivers and the lake by predicting nutrient concentrations, taking water quality, meteorological conditions, riverine import, and agricultural Non-Point Source (NPS) loads into consideration. Compared to single-stage deep learning models developed using classical methods, the two-stage model reduces Mean Absolute Percentage Error (MAPE), Mean Absolute Error (MAE), and Root Mean Square Error (RMSE), indicating enhanced prediction accuracy. Shapley Additive Explanation (SHAP) analysis is further employed to identify key contributing features. Precipitation emerges as the primary feature in the first stage, while in the second stage, disparities in the most contributing features for two zones of the lake are revealed due to dam isolation and water diversion projects. In the main zone, the primary predicting features are temperature and agricultural NPS features, while in the dam-isolated zone, Secchi depth is the key predictor, highlighting spatial–temporal variations in driving features. Our model contributes a novel deep learning framework and valuable insights for water quality management in large lakes, emphasizing the importance of considering the dynamic interplay of features or factors in the ’land-river-lake’ system.

Geochemical Indicators on the Central Tibetan Plateau Lake Sediments: Historical Climate Change and Regional Sustainability

Geochemical Indicators on the Central Tibetan Plateau Lake Sediments: Historical Climate Change and Regional Sustainability

Eutrophication weakens the positive biodiversity–productivity relationship of benthic diatoms in plateau lakes

Context Freshwater primary productivity is threatened by the decline in biodiversity associated with nutrient enrichment, but there is still uncertainty about how the biodiversity and productivity relationship (BPR) varies with the trophic states. Aims We aimed to examine the variation of benthic diatom BPRs in three plateau lakes with different trophic states and their underlying driving mechanisms. Methods We examined the relationship between diatom taxonomic and functional diversity, niche width, and niche overlap with productivity. Key results The taxonomic and functional diversity, niche width and productivity of benthic diatoms were highest in the mesotrophic lake. The benthic diatom BPRs were linear and positive, with the slope of BPRs being the lowest in eutrophic lake. Motile, non-attached and small-sized diatoms were dominant in eutrophic lake. Nutrient concentrations indirectly affected primary productivity by influencing algal community structure, niche width and biodiversity change. Conclusions Diatom productivity and diversity showed a positive relationship, but nutrient enrichment weakened this relationship. By combining taxonomic and functional diversity indices, supplemented by niche analysis, we can further understand the variation of diatom productivity. Implications The results provide a basis for predicting the changes in BPRs of benthic diatoms in the littoral zone with different trophic states.

Long-term trends in water transparency of Tibetan Plateau lakes and the response to extreme climate events

Water transparency, as indicated by the Secchi disk depth (Zsd), is a key parameter for assessing the quality of aquatic environments, reflecting the ability of light to penetrate through the water column. In the Tibetan Plateau (TP), where lakes are abundant yet remote and challenging to access, remote sensing techniques offer a promising approach for monitoring Zsd over large spatial scales. In this study, we used the semianalytical -based Zsd algorithm to study the temporal and spatial dynamics of water transparency over TP during the period from 2003 to 2022. The results show that the 173 lakes have a mean value of Zsd is 3.64 ± 2.4 m for long term, and generally with the significantly increasing change trends in the past 20 years. In the central Tibetan Plateau (CTP) region, lake transparency showed a positive correlation with lake surface temperature (r = 0.73) and a negative correlation with precipitation (r = −0.54), highlighting the region’s heightened sensitivity to meteorological changes compared to other areas. The spike in water clarity observed in the CTP region may be linked to alterations in lake hydrodynamics driven by the extremely climate events (i.e., El Niño). These results indicated the importance of considering regional climatic factors when interpreting fluctuations in water transparency.

Simulation and control of the cyanobacterial bloom biomass in a typical plateau lake based on the logistic growth model: A case study of Xingyun Lake

The simulation and early warning of cyanobacterial blooms in lakes are of great significance. Controlling the growth of cyanobacteria in plateau lakes is challenging due to the unique geographical environment, climatic conditions, and impact of anthropogenic activities. Therefore, conducting simulations and early warning is crucial to effectively control cyanobacterial blooms in plateau lakes. This study aimed to investigate Xingyun Lake, a representative plateau lake in China, using the logistic growth model to analyze cyanobacterial growth patterns and assess the effects of control projects, along with the influence of meteorological and environmental factors. Moreover, the study proposed a method for establishing control curves and ranges for managing cyanobacterial blooms. The results demonstrated that the chlorophyll-a concentration in the effluent decreased by an average of 97.74% compared with that in the influent after implementing the integrated “deep-well pressure algal control” and “ecological purification for algae-water separation” processes in Xingyun Lake. The total annual decrease in chlorophyll-a was approximately 3.40 times the lake's total chlorophyll-a content. The growth of cyanobacteria in Xingyun Lake followed a logistic pattern during the blooming period, before and after implementing control projects (from 2018 to 2022), with the overall growth trend from 2010 to 2022 aligning with the logistic growth model. The study identified lower temperatures and precipitation, reduced nitrogen and phosphorus loads, and a higher nitrogen-to‑phosphorus ratio as the main environmental factors inhibiting cyanobacterial growth. Establishing logistic control curves for cyanobacterial blooms and sustaining the algal control project before the transition point effectively reduced the maximum chlorophyll-a concentration and attenuated cyanobacterial growth rate throughout the year. This study offered novel perspectives for preventing and controlling cyanobacterial blooms, offering practical guidance for lake management, especially in plateau regions.

Carrying Capacity of Water Environment and the Associated Optimization of Socioeconomic Structure of Yangzong Lake Basin, China

Yangzong Lake is the third largest deep-water plateau lake in Yunnan, China. Rapid socioeconomic development of the basin has resulted in pollution of water environment. This study aimed to identify the carrying capacity of water environment and to conduct the associated optimization of socioeconomic development. The results of this study showed that: (1) The carrying capacities of tributary rivers were small in relation to that of the lake. The maximum allowable annual loads of chemical oxygen demand (COD), ammonia nitrogen (NH3-N), and total phosphorus (TP) into the main rivers of the basin were 449.37, 24.73, and 5.38 tons, respectively. (2) Under the planning scenario, COD and NH3-N loads remain the primary constraints on economic and social development in the watershed. (3) In further optimizing the structure of the plantation industry, focusing on strengthening the collection and treatment capacity of rural domestic sewage, the watershed can achieve high-quality development of the tourism industry. The tourism output value in 2025 and 2035 can carry up to 20.28 billion CNY (growth rate: around 15.44%) and 76.80 billion CNY (growth rate: around 14.64%), respectively. This study can provide basic support for the future economic and social development of the watershed for decision-makers.

Optimal Mapping of Soil Erodibility in a Plateau Lake Watershed: Empirical Models Empowered by Machine Learning

Soil erodibility (K) refers to the inherent ability of soil to withstand erosion. Accurate estimation and spatial prediction of K values are vital for assessing soil erosion and managing land resources. However, as most K-value estimation models are empirical, they suffer from significant extrapolation uncertainty, and traditional studies on spatial prediction focusing on individual empirical K values have neglected to explore the spatial pattern differences between various empirical models. This work proposed a universal framework for selecting an optimal soil-erodibility map using empirical models enhanced by machine learning. Specifically, three empirical models, namely, the erosion-productivity impact calculator model (K_EPIC), the Shirazi model (K_Shirazi), and the Torri model (K_Torri) were used to estimate K values. Random Forest (RF) and Gradient-Boosting Decision Tree (GBDT) algorithms were employed to develop prediction models, which led to the creation of three K-value maps. The spatial distribution of K values and associated environmental covariates were also investigated across varying empirical models. Results showed that RF achieved the highest accuracy, with R2 of K_EPIC, K_Shirazi, and K_Torri increasing by 46%, 34%, and 22%, respectively, compared to GBDT. And distinctions among environmental variables that shape the spatial patterns of empirical models have been identified. The K_EPIC and K_Shirazi are influenced by soil porosity and soil moisture. The K_Torri is more sensitive to soil moisture conditions and terrain location. More importantly, our study has highlighted disparities in the spatial patterns across the three K-value maps. Considering the data distribution, spatial distribution, and measured K values, the K_Torri model outperformed others in estimating soil erodibility in the plateau lake watershed. This study proposed a framework that aimed to create optimal soil-erodibility maps and offered a scientific and accurate K-value estimation method for the assessment of soil erosion.

Seasonal dynamics and driving mechanisms of microbial biogenic elements cycling function, assembly process, and co-occurrence network in plateau lake sediments

Microbial community diversity significantly varies with seasonality. However, little is known about seasonal variation of microbial community functions in lake sediments and their associated environmental influences. In this study, metagenomic sequencing of sediments collected from winter, summer, and autumn from Caohai Lake, Guizhou Plateau, were used to evaluate the composition and function of sediment microbial communities, the potential interactions of functional genes, key genes associated with seasons, and community assembly mechanisms. The average concentrations of nitrogen (TN) and phosphorus (TP) in lake sediments were higher, which were 6.136 and 0.501 g/kg, respectively. TN and organic matter (OM) were the primary factors associated with sediment community composition and functional profiles. The diversity and structure of the microbial communities varied with seasons, and Proteobacteria relative abundances were significantly lower in summer than in other seasons (58.43–44.12 %). Seasons were also associated with the relative abundances of functional genes, and in particular korA, metF, narC, nrfA, pstC/S, and soxB genes. Network complexity was highest in the summer and key genes in the network also varied across seasons. Neutral community model analysis revealed that the assembly mechanisms related to carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) cycle-related genes were primarily associated with random processes. In summary, diverse functional genes were identified in lake sediments and exhibited evidence for synergistic interactions (Positive proportion: 74.91–99.82 %), while seasonal factors influenced their distribution. The results of this study provide new insights into seasonal impacts on microbial-driven biogeochemical cycling in shallow lakes.

Shallow Groundwater Around Plateau Lakes： Spatiotemporal Distributions of Dissolved Carbon and Its Driving Factors

Dissolved carbon in groundwater plays an important role in carbon cycling and ecological function maintenance, and its concentration level affects the migration and transformation of pollutants in groundwater. To understand the spatiotemporal variation characteristics of dissolved carbon and its driving factors in shallow groundwater around plateau lakes, variations in the concentrations of dissolved organic carbon （DOC）, inorganic carbon （DIC）, and total carbon （DTC） and their driving factors in shallow groundwater （n = 404） around eight plateau lakes were analyzed. The results indicated that the average values of ρ（DOC）, ρ（DIC）, and ρ（DTC） in shallow groundwater around plateau lakes were 8.23, 49.01, and 57.84 mg·L-1, respectively, with the ρ（DOC） in 79.0% of shallow groundwater samples exceeding 5 mg·L-1. There were no significant differences in the DOC, DIC, and DTC concentrations between rainy and dry seasons, whereas the change in dissolved carbon concentrations in shallow groundwater were strongly affected by the intensity of agricultural intensification and the depth of groundwater table； the DOC, DIC, and DTC concentrations in shallow groundwater from facility agricultural regions （SFAR）, cropland fallow agricultural regions （CFAR）, and intensive agricultural regions with deeper groundwater tables （DIAR） were significantly reduced by 25.8% - 56.6%, 14.0% - 32.9%, and 16.6% - 36.7%, respectively, compared with those in intensive agricultural regions with shallower groundwater tables （SIAR）. Additionally, the dissolved carbon concentrations in shallow groundwater from DIAR were significantly lower than those of SFAR and CFAR. RDA revealed that physicochemical factors in water and soil significantly explained the changes in the dissolved carbon concentrations. Moreover, the dissolved carbon concentrations in shallow groundwater around Yilong Lake were significantly higher than those of other lakes, whereas that of Chenghai Lake was significantly lower than that of other lakes. Our study highlights that agricultural intensification intensity and groundwater table depth jointly drove the variations in dissolved carbon concentrations in shallow groundwater around plateau lakes. The study results are expected to provide a scientific basis for understanding the carbon cycle in plateau lake areas with underground runoff flowing into lakes and evaluating the attenuation of pollutants by dissolved carbon in shallow groundwater.

Bacterial and Archaeal Communities in Erhai Lake Sediments: Abundance and Metabolic Insight into a Plateau Lake at the Edge of Eutrophication.

The littoral zones of lakes are potential hotspots for local algal blooms and biogeochemical cycles; however, the microbial communities within the littoral sediments of eutrophic plateau lakes remain poorly understood. Here, we investigated the taxonomic composition, co-occurrence networks, and potential functional roles of both abundant and rare taxa within bacterial and archaeal communities, as well as physicochemical parameters, in littoral sediments from Erhai Lake, a mesotrophic lake transitioning towards eutrophy located in the Yunnan-Guizhou Plateau. 16S rRNA gene sequencing revealed that bacterial communities were dominated by Proteobacteria, Bacteroidetes, and Chloroflexi, while Euryarchaeota was the main archaeal phylum. Co-occurrence network analysis revealed that keystone taxa mainly belonged to rare species in the bacterial domain, but in the archaeal domain, over half of keystone taxa were abundant species, demonstrating their fundamental roles in network persistence. The rare bacterial taxa contributed substantially to the overall abundance (81.52%), whereas a smaller subset of abundant archaeal taxa accounted for up to 82.70% of the overall abundance. Functional predictions highlighted a divergence in metabolic potentials, with abundant bacterial sub-communities enriched in pathways for nitrogen cycling, sulfur cycling, and chlorate reduction, while rare bacterial sub-communities were linked to carbon cycling processes such as methanotrophy. Abundant archaeal sub-communities exhibited a high potential for methanogenesis, chemoheterotrophy, and dark hydrogen oxidation. Spearman correlation analysis showed that genera such as Candidatus competibacter, Geobacter, Syntrophobacter, Methanocella, and Methanosarcina may serve as potential indicators of eutrophication. Overall, this study provides insight into the distinct roles that rare and abundant taxa play in the littoral sediments of mesotrophic plateau lakes.

Shallow groundwater table fluctuations weaken nitrogen accumulation in the thin layer vadose zone of cropland around plateau lakes, Southwest China

Excessive accumulation of nitrogen (N) in the soil profile in the intensive agricultural region will seriously threaten groundwater quality and safety. However, the impact of shallow groundwater table (SGWT) fluctuations driven by seasonal variations on the N accumulation characterizations in the soil profiles has not been well quantified, particularly in the regions with thin layer vadose zone. Through in-situ monitoring and simulation experiments, the changes in the SGWT and N accumulation of soil profile in intensive cropland around 7 plateau lakes in Yunnan were studied during the rainy season (RS) and dry season (DS), and the N loss in soil profile of cropland driven by SGWT fluctuations was estimated. The results showed that the SGWT and N accumulation in soil profile of cropland around the plateau lakes had obvious seasonal variation characteristics. The proportion of N storage in different forms in 60–100 cm soil layer in the RS was greater than that in the DS, particularly the proportion of NH4+-N storage was as high as 55 %, while N accumulation in surface soil was obvious in the DS. Compared with the DS, due to the rising SGWT in the RS, the maximum storages of TN and NO3−-N in the 0–100 cm soil layer decreased by17% and 36 %, respectively. The TN loss intensities from the 0–100 cm soil profiles of cropland around Fuxian Lake, Yilong Lake, Qilu Lake, Dianchi Lake, Yangzong Lake, Erhai Lake, and Xingyun Lake were 74, 54, 127, 105, 93, 72 and 207 kg/ha, respectively. Moreover, if the SGWT was <30 cm, the average TN loss intensity and amount could reach 177 kg/ha and 1250 t, respectively. Therefore, the SGWT regulation was one of the key measures to reducing soil N loss from the thin layer vadose zone of cropland around plateau lakes and improving groundwater quality.

Water temperature and salt ions respectively drive the community assembly of bacterial generalists and specialists in diverse plateau lakes

Plateau lakes (e.g., freshwater and saltwater lakes) are formed through intricate processes and harbor diverse microorganisms that mediate aquatic ecosystem functions. The adaptive mechanisms of lake microbiota to environmental changes and the ecological impacts of such changes on microbial community assembly are still poorly understood in plateau regions. This study investigated the structure and assembly of planktonic bacterial communities in 24 lakes across the Qinghai-Tibetan and Inner Mongolia Plateaus, with particular focus on habitat generalists, opportunists, and specialists. High-throughput sequencing of the 16S ribosomal RNA genes revealed that bacterial generalists had a lower species number (2196) but higher alpha diversity than the specialist and opportunist counterparts. Taxonomic dissimilarity and phylogenetic diversity analyses unraveled less pronounced difference in the community composition of bacterial generalists compared to the specialist and opportunist counterparts. Geographical scale (14.4 %) and water quality (12.6 %) emerged as major ecological variables structuring bacterial communities. Selection by water temperature and related variables, including mean annual temperature, elevation, longitude, and latitude, mainly shaped the assembly of bacterial generalists. Ecological drift coupled with selection by salt ions and related variables, including total phosphorus, chlorophyll a, and salinity, predominantly drove the assembly of bacterial specialists and opportunists. This study uncovers distinct bacterial responses to interacting ecological variables in diverse plateau lakes and the ecological processes structuring bacterial communities across various lake habitats under anthropogenic disturbance or climate change.

Multi-Source Remote Sensing Analysis of Yilong Lake’s Surface Water Dynamics (1965–2022): A Temporal and Spatial Investigation

With the acceleration of global warming and the intensification of anthropogenic activities, numerous lakes worldwide are experiencing reductions in their water surface areas. Yilong Lake, a typical shallow plateau lake located on the Yunnan–Guizhou Plateau in China, serves as a crucial water resource for local human production, daily life, and ecosystem services. Hence, long-term comprehensive monitoring of its dynamic changes is essential for its effective protection. However, previous studies have predominantly utilized remote sensing data with limited temporal resolution, thus failing to reflect the long-term variations in Yilong Lake’s water body. This study employs high temporal resolution monitoring, utilizing multi-source satellite data (e.g., KeyHole, Landsat, HJ-1 A/B) images spanning from 1965 to 2022 to investigate the changes in Yilong Lake’s surface area, analyzing the influencing factors and ecological impacts of these changes. The results indicate that from 1965 to 2022, Yilong Lake’s water surface area decreased by 8.33 km2, with a maximum surface area of 40.49 km2 on January 7, 1986, and a minimum surface area of 10.64 km2 on April 20, 2013. These changes are characterized by three significant phases: (1) a rapid shrinking phase (1965–1979); (2) a fluctuating shrinking period (1986–2016); and (3) an expanding recovery phase (2016–2022). Spatially, the most significant shrinkage was observed along the southern and southwestern shores of the lake. The driving factors varied across different periods: sunshine duration was the dominant influence during the rapid shrinking phase (1965–1979), accounting for 82% of the changes; population and cropland area were the main drive factors during the fluctuating shrinking period (1986–2016), accounting for 56% of the changes; and during the expanding recovery phase (2016–2022), the population accounted for 75% of the changes in the lake’s surface area. Currently, the protection of Yilong Lake depends on water supplementation and strict regulation of outflow, resulting in the lake exhibiting characteristics similar to a reservoir. This long-term investigation provides baseline information for future lake monitoring. Our research findings can also guide decision-makers in urban water resource management and environmental protection, ensuring the scientific and rational use of watershed water resources, effectively curbing the shrinkage of Yilong Lake, and achieving long-term sustainable restoration of the lake’s ecology.

Heterogenization of microplastic communities in lakes of the Qinghai-Tibetan Plateau driven by tourism and transport activities

The Qinghai-Tibetan Plateau has a booming tourism industry and an increasingly sophisticated road system. There is a paucity of studies quantifying the contributions of anthropogenic and natural factors to microplastic pollution in remote plateau areas. In this study, water and sediment samples were collected from eight lake tourist attractions and four remote lakes in northern and southern regions of the Qinghai-Tibetan Plateau. Microplastics were detected in all samples, with a mean abundance of 0.78 items/L in water and 44.98 items/kg in sediment. The abundance of microplastics in the study area was lower than previously observed in more populated areas of China. Small-sized (<1 mm and 1–2 mm), fiber, and transparent microplastics were predominant, with polyethylene and polypropylene microplastics as the primary polymer types. The compositions of microplastic communities indicated that tourism and road networks were the major sources of microplastics in the lakes. Distance-decay models revealed greater influence of environmental distances on microplastic community similarity than geographic distance. Compared to climate factors, urban spatial impact intensity and traffic flow impact played a leading role in the structuring of microplastic communities in lake water and sediment. Our findings provide novel quantitative insights into the role of various factors in shaping the distribution patterns of microplastic communities in plateau lakes.

Appendopyricularia guttulata sp. nov., a lignicolous freshwater fungus from Dianchi Lake in Yunnan, China

During an investigation into species diversity of lignicolous freshwater fungi from the plateau lakes in Yunnan Province, China, a hyphomycetous fungus was collected from Dianchi Lake. The new isolate was placed in Appendopyricularia as a sister taxon of Appendopyricularia juncicola within Barbatosphaeriaceae based on the phylogenetic analysis of combined ITS and LSU sequence data. The fungus is characterized by acrogenous, fusoid, guttulate conidia that are 3–4 septate and have a flexuous central apical appendage. It exhibits more pronounced guttulate appendages and more prominent denticle sporulation structure. Therefore, Appendopyricularia guttulata is introduced as a new species based on morphological characteristics and phylogenetic evidence. The detailed description and illustrations of the new species are provided, as well as the morphological comparison with similar taxa.