Lentic Research Articles

Presence of mucilage and low omega-3 fatty acid contents in phytoplankton impair the quality of phytoplankton diet for zooplankton

Phytoplankton are a crucial basal dietary source for consumers in lake ecosystems. The dietary quality of phytoplankton for zooplankton has been investigated in terms of molecules (e.g., fatty acids) and stoichiometry. However, little is known on the effects of algal mucilage on the dietary quality of phytoplankton. Therefore, this study aimed to investigate the effects of mucilage and fatty acid contents in phytoplankton on dietary quality. Zooplankton (Daphnia pulicaria) were reared with a single species of phytoplankton as the diet. Eighteen phytoplankton types were used. Algal dietary quality was evaluated based on the growth, reproduction, and survival rates of D. pulicaria for each dietary algal species during the feeding experiments. The results demonstrated that the dietary quality of phytoplankton with mucilage decreased significantly among the green algae. Green algae without mucilage had high omega-3 fatty acid contents, which increased its dietary quality. The quality of cyanobacteria diet was low for D. pulicaria regardless of the absence or presence of mucilage and fatty acid contents. . The results show that the presence of mucilage may have reduced ingestion and digestion by zooplankton and indicate that this algal succession will have a negative impact on lake ecosystems.

Diverse effects of climate changes and anthropogenic activities on sedimentary nitrogen isotope (δ15Nsed.) in lakes across different regions of China since the late Holocene

Nitrogen plays a vital role in the Earth's systems. Nitrogen isotopes have been widely used in environmental and climatic research. Various biogeochemical processes and nitrogen sources contribute to the sedimentary organic matter. Therefore, environmental implications of sedimentary nitrogen isotope (δ15Nsed.) require further investigation. In this study, we report and compile the δ15Nsed. records from eight lakes in China influenced by either climate changes or anthropogenic activities since the late Holocene to determine the major forcing factors of δ15Nsed.. Our results showed that: (1) During the late Holocene, lacustrine δ15Nsed. was mainly regulated by natural climate changes, such as temperature, precipitation, or both as anthropogenic activities were weak. (2) The impact of gradually increasing anthropogenic disturbances on δ15Nsed. in the different lakes varied. Globally, the declining lacustrine δ15Nsed. values could be attributed to atmospheric reactive nitrogen deposition. However, on the regional catchment scale, the increased δ15Nsed. values in lakes may be related to increased nutrient input and higher primary production caused by increased anthropogenic activities, whereas the rapid decline of δ15Nsed. values in lakes is possibly related to more nutrition input and 15N-depleted organic matter input resulting excessive anthropogenic activities. Our study suggests that the impact of anthropogenic activities on lake ecosystems gradually increased in recent decades, and the amplitudes in variations of δ15Nsed. values in some lakes exceeded those during periods of weak anthropogenic disturbances. If not properly managed, anthropogenic disturbances may outweigh nature (i.e. temperature, precipitation) as the leading cause of lake ecosystems in the future.

The study of riparian areas in tourism: toward a conceptual framework of riparian tourism

Abstract. Riparian areas serve as interfaces between terrestrial and aquatic (including glaciers and glacial lakes) ecosystems, playing a crucial role in shaping landscapes, supporting flora and fauna diversity, and supporting human communities. Thus, riparian areas maintain ecological, cultural, and socio-economic resilience, enriching communities dependent on these ecosystems. Riparian areas are of great ecological value and have immense potential for tourism. However, the touristic value of riparian zones has largely remained unexplored and is confined mainly to the area of river-based recreational activities. This paper proposes “riparian tourism” as a holistic and sustainable form of tourism that encompasses both consumptive and non-consumptive forms of tourism. The exploration of the subject and the conceptualization of this potentially globally appealing form of tourism have the potential to offer entrepreneurial and touristic opportunities, especially for local communities, thereby ensuring not only ecological but also socio-economic benefits. The paper delves into creating a conceptual framework for riparian tourism, e.g. cryo-tourism. The research in this sense contributes greatly to increasing the discourse on sustainable tourism and emphasizes the urgency to incorporate tourism and conservation actions in riparian areas which are greatly impacted by the changing climate.

Assessment of the Impact of Meteorological Variables on Lake Water Temperature Using the SHapley Additive exPlanations Method

The water temperature of lakes is one of their fundamental characteristics, upon which numerous processes in lake ecosystems depend. Therefore, it is crucial to have detailed knowledge about its changes and the factors driving those changes. In this article, a neural network model was developed to examine the impact of meteorological variables on lake water temperature by integrating daily meteorological data with data on interday variations. Neural networks were selected for their ability to model complex, non-linear relationships between variables, often found in environmental data. Among various architectures, the Artificial Neural Network (ANN) was chosen due to its superior performance, achieving an R2 of 0.999, MSE of 0.0352, and MAE of 0.1511 in validation tests. These results significantly outperformed other models such as Multi-Layer Perceptrons (MLPs), Recurrent Neural Networks (RNNs), and Long Short-Term Memory (LSTM). Two lakes (Lake Mikołajskie and Sławskie) differing in morphometric parameters and located in different physico-geographical regions of Poland were analyzed. Performance metrics for both lakes show that the model is capable of providing accurate water temperature forecasts, effectively capturing the primary patterns in the data, and generalizing well to new datasets. Key variables in both cases turned out to be air temperature, while the response to wind and cloud cover exhibited diverse characteristics, which is a result of the morphometric features and locations of the measurement sites.

Mapping and assessing the future provision of lake ecosystem services in Lithuania

Lakes supply multiple ecosystem services (ES), key to supporting socio-ecologic systems and human well-being. In the context of future land use and climate changes, it is imperative to anticipate potential impacts on lake ES supply. Hence, studies that deal with future lake ES, such as mapping, are lacking. In this work, we mapped and assessed the future supply of three ES: (1) maintenance of nursery conditions (nursery ES), (2) maintenance of chemical conditions of freshwaters (nutrient regulation ES), and (3) direct and indirect cultural outputs (recreation ES) in Lithuania. Four future scenarios were utilised, integrating land use and climate changes: A0 - business as usual; A1-urbanisation; A2: land abandonment and afforestation; and A3 - agricultural intensification. The projected year was 2050, following the intermediate Representative Concentration Pathway (RCP 4.5). The future scenarios were simulated using the open-source software Dinamica EGO based on a 6-step modelling framework. Statistical differences among the scenarios and ES were analysed by applying a Kruskal-Wallis ANOVA test. Spatial analysis was done by performing a Moran's I and Getis-Ord (Gi∗) hotspot analysis. The results showed significant differences in nursery and nutrient regulation ES. The highest supply in nursery ES was observed for the A0 scenario. For nutrient regulation ES, the lowest ES supply was identified for the A1 scenario and for recreation ES, the highest was found in the A2 scenario. The eastern and northeastern regions of Lithuania showed a high ES supply. Hot spots were only identified in the eastern region. These regions are associated with a high area covered by forests and protected areas. The central region shows a low ES supply, identified as a cold spot where the agricultural landscape dominates. The results of the PCA analysis revealed an association between nursery and recreation ES. Nutrient regulation was not associated with the other two ES. Mapping and assessing the impact of future scenarios is vital to anticipating the potential dynamics of lake ES, especially in the context of climate change. This information is essential in the context of environmental management, helping decision-makers to ensure a sustainable ES supply and contributing to human wellbeing.

Spatial distribution of heavy metal contamination and risk indices of surface sediments in high-altitude lakes.

Lake ecosystems in northern Pakistan are the most critical resources that maintain and regulate water flow for downstream agricultural, domestic, industrial, and ecological processes. One consequence of these processes is that ecosystems deposit heavy metals (HMs), where lake stagnant conditions result in high vulnerability of water resources. For this purpose, the present study examined HMs such as cadmium (Cd), chromium (Cr), cobalt (Co), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) concentrations in high-altitude lakes (HAL) sediments of Mansehra district, northern Pakistan. Sediment samples were collected from the five HAL. This study used HM concentrations in lake sediments for the pollution factors such as contamination factor (Cf), pollution load index (PLI), sediment pollution index (SPI), ecological risk assessment (ERA), and risk index (RI). Among HMs, Fe showed the uppermost levels of 1410mg/kg in lake sediment, while Cd with lowermost levels of 1.05mg/kg. Results revealed that most HM concentrations in HAL sediments were within the threshold of sediments quality guidelines (SQGs), except for Cd. Among lakes, the sediments of Siri Lake showed higher contamination of HMs than others. Siri Lake sediments also showed higher Cf, PLI, ERA, and RI values than others. The majority of HMs in HAL sediments showed no contamination, except for Cd (considerable) and Pb (moderate) levels to the exposed aquatic ecosystem. This study revealed that 95% of sediment samples in HAL were noted low to medium-level risks to the exposed aquatic communities. Statistical and geospatial analyses revealed that geogenic sources of contamination are a significant contributor to HM contamination of HAL sediments compared to others.

Synthesis of a hydrological, water chemistry, and contaminants research program in the Peace-Athabasca Delta (Canada) to inform long-term monitoring of shallow lakes

In a multistressor world, evidence-based stewardship of aquatic ecosystems requires long-term monitoring data to understand the timing and magnitude of environmental change and potential causes. At the Peace-Athabasca Delta (PAD; northeastern Alberta, Canada), concern for aquatic ecosystem degradation has triggered renewed and urgent calls by Indigenous, national, and international governance bodies for implementation of a long-term lake monitoring program capable of tracking changes in hydrological conditions and contaminant deposition attributable to major energy projects located upstream, climate change, and other unnatural and natural processes. Challenges imposed by the delta's size, hydrological complexity, inaccessibility of lakes, and other factors, however, have long impeded implementation of a delta-wide lake monitoring program. To address this pressing need, here we review and synthesize results obtained during 7 years (2015–2021) of intensive, multifaceted research at 60 shallow lakes spanning the delta's broad hydroecological gradients to inform an integrated hydrology, water chemistry, and contaminants monitoring program. The research involved systematic, repeated measurements of water isotope composition, water depth variation, water chemistry and turbidity, and metal(loid) concentrations in lake surface sediment and periphytic biofilm. Results reveal marked spatial and temporal variation of hydrological processes and their affects on lake water balance and depth, strong association between hydrological processes and lake water chemistry, and that concentrations of nickel and vanadium (key oil sands indicators) remain within the range of natural variation. Correspondence of generalized additive model trendlines for isotope-derived lake evaporation-to-inflow ratios and water chemistry with climate indices (Pacific Decadal Oscillation, Oceanic Niño Index) demonstrates the sensitivity, and predictability, of lake ecosystem processes in the delta to large-scale climatic patterns. We provide recommendations for field sampling, sample analysis, data display, and integration of information for ongoing monitoring at the PAD. These approaches are readily transferable to other complex landscapes with abundant shallow waterbodies threatened by multiple stressors that may alter hydrological regimes and contaminant delivery.

The Great Lakes Winter Grab: Limnological data from a multi‐institutional winter sampling campaign on the Laurentian Great Lakes

AbstractInterest in winter limnology is growing rapidly, but progress is hindered by a shortage of standardized multivariate datasets on winter conditions. Addressing the winter data gap will enhance our understanding of winter ecosystem function and of lake response to environmental change. Here, we describe a dataset generated by a multi‐institutional winter sampling campaign across all five Laurentian Great Lakes and some of their connecting waters (the Great Lakes Winter Grab). The objective of Winter Grab was to characterize mid‐winter limnological conditions in the Great Lakes using standard sample collection and analysis methods. Nineteen research groups sampled 49 locations varying widely in depth and trophic status, collecting a range of limnological data. This dataset includes physical, chemical, and biological measurements. These data can be used to examine diverse aspects of Great Lakes ecosystems or integrated with winter observations from other lakes to improve understanding of winter limnology across different aquatic systems.

Reproductive biology of long-whiskered catfish (Mystus aor) relative to temperature and precipitation from the Kaptai Lake of Bangladesh.

Life-history information is necessary for effective conservation, aquaculture development and broodstock management of fishing populations, especially for fish with significant economic exploitation. Aiming to characterise the life-history traits in relation to the environmental parameters of the long-whiskered catfish, Mystus aor, a commercially important species from Kaptai Lake, Bangladesh, different life-history data were analysed. The monthly condition factor (K) ranged from 1.15 to 1.41, and the relative condition factor (Kn) ranged from 0.14 to 0.25. The estimated relative fecundity was 18474-55504 eggs/per fish, and the maximal oocyte diameter was found in May (0.83 ± 0.11μm). The lengths at first sexual maturity (Lm) for male and female M. aor were 49.5 cm and 54.1 cm, respectively. The GSI was peaked in May for both males and females, and histological analysis also revealed the presence of yolk granules and several mature spermatids in April and May in both sexes. Analysis of environmental data over 40 years in the Kaptai lake ecosystem indicate the significant increase in the precipitation rate in spawning month which is highly correlated with the spawning season. The findings of the current study will serve as a baseline for the conservation and broodstock management in the Kaptai Lake of Bangladesh.

Uncovering the Anthropogenic Influences on Water Quality: A Case of Lake Victoria Shores, Entebbe, Uganda

Lakes serve as vital ecosystems, providing freshwater resources and habitats for diverse species. However, human activities, particularly around lakeshores, have led to significant environmental degradation, including heavy metal contamination. Lake Victoria, the second-largest freshwater lake globally, has been severely impacted by pollution from industrial, agricultural, and urban sources. This research aims at examining the influence of the anthropogenic activities on the water quality of Lake Victoria. Specifically, the study tried to determine the activities undertaken at the Lake shores of Lake Victoria; determined the physico-chemical parameters of the water from the shores and the heavy metal concentration in the water samples obtained from the shores of Lake Victoria. This study utilized a cross-sectional and experimental research designs to assess water quality and anthropogenic influences around Lake Victoria. A total of 150 residents from selected communities were surveyed using a semi-structured questionnaire to gather demographic information, perceptions of water quality and the activities carried out within the shores of Lake Victoria. Water samples were collected from multiple sites along the lake shores for analysis of heavy metals using the Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Water quality parameters were determined In-situ using a multi-parameter water testing kit and Hanna instrument. Results showed that the anthropogenic activities that could have contributed to water degradation include: fishing, transport, agriculture and construction among others. Apart from pH which was outside the permissible limits, all the other water parameters were within the WHO permissible limits. Considering the heavy metal concentration, all the sampled sites apart from one inlet, had the concentrations above the WHO permissible levels an indication of significant heavy metal contamination in the Lake Victoria shores. These findings highlight the urgent need for targeted pollution control measures and regular monitoring to mitigate further environmental degradation. Effective interventions, including stricter regulations and sustainable land use practices within the Victoria shores are essential for safeguarding the lake's ecosystem and the health of surrounding communities.

Ecological Assessment of Phytoplankton Diversity and Water Quality to Ensure the Sustainability of the Ecosystem in Lake Maybalyk, Astana, Kazakhstan

Microalgae in planktonic communities are the main producers of biomass in lake ecosystems; however, their stability is influenced by many environmental factors. This study aims to assess the ecological state of Lake Maybalyk, located in Astana (Kazakhstan), based on the study of the taxonomic diversity and structure of phytoplankton, zooplankton, and the physico-chemical properties of the water. From 2019 to 2021, samples were taken for phytoplankton analysis, hydrochemical analysis of the water, zooplankton, and saprobiological analysis of the algocenosis. The study also investigated the main morphometric parameters of the lake, as well as the composition of hydrobionts, such as zooplankton, zoobenthos, and ichthyofauna. The analysis of phytoplankton revealed the presence of 97 species and intraspecific taxa of microalgae, with 71 types of microalgal indicators indicating water saprobity. The planktonic algoflora in Lake Maybalyk is predominantly composed of diatoms (Bacillariophyta) and green algae (Chlorophyta), which play a vital role in oxygen production and the food chain within the reservoir. Based on the Pantle–Buck saprobity index (2.15–2.5), the water quality in Lake Maybalyk is classified as moderately polluted. The assessment of the water quality, considering the number and composition of indicator phytoplankton species, places Lake Maybalyk in class III (β-mesosaprobic). The hydrochemical indicators align with the hydrobiological indicators, confirming the water quality as class III. The trophic status of the reservoir, during the study period, can be described as average. The obtained data on both the hydrobiological and hydrochemical indicators correlate, suggesting satisfactory water quality and the ability of the reservoir to purify itself. This study contributes to the sustainable management of water resources, by providing essential data on the ecological state of Lake Maybalyk. The results underscore the importance of continuous biomonitoring, with microalgae as indicators of water quality, which is crucial for developing effective ecosystem conservation strategies.

Monitoring the Dynamics of Aquatic Vegetation in a Typical Shallow Lake Using the Water Bloom Index Algorithm-A Case Study in Bao' an Lake in the Middle Reaches of the Yangtze River.

Understanding changes in the distribution and coverage of aquatic vegetation (AV) is of great significance for the restoration of lake ecosystems. In this study, the vegetation and bloom indices (VBI) algorithm were used to interpret submerged aquatic vegetation (SAV), floating/emergent aquatic vegetation (FEAV), and algal bloom (AB). The dynamics of AV and their influencing factors in Bao' an Lake, in the middle reaches of the Yangtze River in China, were studied from 2000 to 2023. The results showed that (1) the VBI algorithm can accurately distinguish AV and AB of different life forms with an overall accuracy of 93% and a kappa coefficient of 0.86. (2) Macrophyte coverage decreases. AV grew vigorously in spring, and SAV was the dominant type within it, whereas AV coverage was low in summer, and SAV had no summer species for a long time. In 2000, the coverage of AV was the highest, reaching 64.5%, but a gradual decrease that followed in the coming years finally led to a coverage percentage of less than 5% by 2023. (3) The correlation between SAV coverage and total phosphorus (p < 0.01), total nitrogen (p < 0.05), and water depth/transparency (p < 0.05) in Bao' an Lake were 0.23, 0.28, and 0.32, respectively. (4) The SAV species experienced three stages: richness (before 2003), monotonicity (2004-2020), and final disappearance (2021-present). This study shows that the coverage of AV in Bao' an Lake is too low and the number of SAV species is one (2010-now). Therefore, it is necessary to implement measures to improve vegetation coverage and diversity.

Seasonal assessment of biomarkers in Channa punctata from Tampara Lake, Odisha, India and toxicity of thorium nitrate on fish

Tampara Lake, a freshwater lake in the Chatrapur beach placer deposits of Ganjam, Odisha, India is a well-known tourist attraction. Multiple factors seem to disturb the aquatic life of Tampara Lake, especially fish. Chatrapur beach placers are rich in various heavy minerals including monazite, an ore of thorium, that emits high background radiations and can affect the biota. Run-offs from the monazite mining sites on the beach placers are also presumed to be carried to the lake. Thus, tourism, local transportation, fishing activities, presence of heavy minerals and mining run-offs appear to disrupt the lake's ecosystem. The present work assessed the protein and lipid concentrations in the liver and muscle, nuclear abnormalities in the peripheral blood erythrocytes and histopathology of gills, liver, kidney, intestine and stomach of Channa punctata from Tampara Lake in summer, winter and rainy seasons. The study also documented the effects of thorium nitrate, a byproduct of monazite ore processing, on Channa punctata of non-monazite areas. Channa punctata from the Tampara lake had significantly lower protein and lipid content in the liver and muscle, nuclear deformities and micronuclei in the erythrocytes and deformities in the gill, kidney, liver, stomach and intestine relative to the fish from the non-monazite areas. Seasonal alterations were observed in the protein and lipid content of muscle and liver, gill and kidney structure. Fish from the non-monazite areas treated with sub-lethal concentrations of thorium nitrate showed a dose-dependent response in the protein and lipid content of liver and muscle, erythrocyte nuclear abnormalities and histopathological aberrations. The present study provides evidence that Channa punctata from Tampara Lake have relatively low nutritional value compared to fish from undisturbed non-monazite areas and are probably distressed by the water contamination due to the presence of heavy minerals and anthropogenic interventions.

Stronger biogeographical pattern of bacterioplankton communities than biofilm communities along a riverine ecosystem: a local scale study of the Kaidu river in the arid and semi-arid northwest of China

Although the biogeographical pattern and mechanisms underlying microbial assembly have been well-explored in lentic ecosystems, the relevant scenarios in lotic ecosystems remain poorly understood. By sequencing the bacterial communities in bacterioplankton and biofilm, our study detected their distance-decay relationship (DDR), and the balance between deterministic and stochastic processes, along the Kaidu river in an arid and semi-arid region of northwest China. Our results revealed that bacterioplankton and biofilm had significantly contrasting community structures. The bacterioplankton communities showed a gradually decreasing trend in alpha-diversity from the headwater to the river mouth, contrasting with the alpha-diversity of biofilm communities which was constant along the river length. Both bacterioplankton and biofilm showed significant DDRs along the 500-km river corridor with the slope of the bacterioplankton DDR being steeper than that of the biofilm DDR, which implies a stronger biogeography of bacterioplankton than biofilm. Relative to biofilm communities, the species interactions formed a denser and more complex network in the bacterioplankton communities than in the biofilm communities. Our results also revealed that there was a transition of community assembly from deterministic to stochastic processes upstream to downstream, although both the bacterioplankton and biofilm communities were mainly regulated by deterministic processes within the entire river. All these empirical results expand our knowledge of microbial ecology in an arid and semi-arid lotic ecosystem.

Water Temperature Model to Assess Impact of Riparian Vegetation on Jucar River and Spain

Water temperature is a critical factor for aquatic ecosystems, influencing both chemical and biological processes, such as fish growth and mortality; consequently, river and lake ecosystems are sensitive to climate change (CC). Currently proposed CC scenarios indicate that air temperature for the Mediterranean Jucar River will increase higher in summer, 4.7 °C (SSP5-8.5), resulting in a river water temperature increase in the hotter month; July, 2.8 °C (SSP5-8.5). This will have an impact on ecosystems, significantly reducing, fragmenting, or even eliminating natural cold-water species habitats, such as common trout. This study consists of developing a simulated model that relates the temperature of the river with the shadow generated by the riverside vegetation. The model input data are air temperature, solar radiation, and river depth. The model proposed only has one parameter, the shadow river percentage. The model was calibrated in a representative stretch of the Mediterranean river, obtaining a 0.93 Nash–Sutcliffe efficiency coefficient (NSE) that indicates a very good model fit, a 0.90 Kling–Gupta efficiency index (KGE), and a relative bias of 0.04. The model was also validated on two other stretches of the same river. The results show that each 10% increase in the number of shadows can reduce the river water temperature by 1.2 °C and, in the stretch applied, increasing shadows from the current status of 62% to 76–87% can compensate for the air temperature increase by CC. Generating shaded areas in river restorations will be one of the main measures to compensate for the rise in water temperature due to climate change.

Variation of carbon and nitrogen stable isotope composition in leaves and roots of Littorella uniflora (L.) Asch. in relation to water pH and nutrient availability

In a phytotron experiment, the effects of pH variation and eutrophication on isoetids plants from soft-water lakes specifically the submerged form of Littorella uniflora (L.) Asch. was investigated by analyzing stable carbon and nitrogen isotopes (δ13C and δ15N). Conducted in late October 2020, 200 specimens from Lake Zawiad, near Gdansk, Poland, were examined over 75 days. The study tested three pH levels (∼4.5, ∼7.0, and ∼8.5) and a detailed 12-step nutrient gradient (nitrogen: 0–10 mg/l; phosphorus: 0–0.3 mg/l). The analysis focused on isotopic composition in leaves and roots, revealing that acidic conditions favored higher δ13C values (leaves: −22.67 ‰; roots: −23.23 ‰), suggesting a preference for lighter carbon forms in photosynthesis and intensive use of limited sources of CO2. The neutral pH variant showed the lowest δ13C values (leaves: −25.53 ‰; roots: −25.47 ‰), indicating less optimal conditions. δ15N values exhibited minimal fluctuation across pH levels, with slight variations in acidic and alkaline environments compared to neutral conditions. An observed decrease in δ13C across all pH levels with increased nutrients, alongside a rise in δ15N values, indicates a complex interaction between isotopic composition and environmental factors. Our findings suggest that L. uniflora shows a distinct isotopic response to varying pH levels, with higher δ13C values under acidic conditions potentially indicating enhanced CO2 uptake through a specialized carbon assimilation strategy. This highlights the species' adaptive mechanisms to environmental stressors, suggesting that the isotopic composition of aquatic vegetation can serve as a sensitive indicator of changes in lake ecosystems.

Nationwide occurrence and prioritization of tire additives and their transformation products in lake sediments of China

As a group of emerging contaminants of global concern, tire additives and their transformation products (TATPs) are causing a severe threat to aquatic ecosystems, particularly the highly lethal effects of N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine quinone (6PPD-Q) on certain fish species. Yet, the contamination status of TATPs in the lake ecosystems remains largely uncharacterized. This study conducted the first nationwide monitoring of the distribution characteristics of TATPs in 208 lake sediments collected from five lake regions across China. All the 13 TATPs were identified in lake sediments, with the total levels varying between 1.4 and 1355 ng/g, and 4-hydroxydiphenylamine (4-OH-PPD) as the most dominant. The total levels of TATPs decreased in the following order: Yunnan-Guizhou Plateau > Inner Mongolia-Xinjiang Region, Eastern Plain > Qinghai-Tibet Plateau, and Northeast Plain (p < 0.05). The geographical distribution of TATPs in lake sediments was significantly driven by total organic carbon content, temperature, and population density. N,N’-di-2-naphthyl-p-phenylenediamine, 6PPD-Q, N,N′-diphenyl-p-phenylenediamine, and 4-OH-PPD belonged to high-priority contaminants. Our study emphasizes that emerging pollutant TATPs place significant pressure on lake ecosystems and deserve urgent attention.

Spatio-temporal analysis of habitat suitability for the endangered oriental white stork (Ciconia boyciana) in the wetland ecosystem of northeast China

Human-induced habitat transformation often leads to habitat degradation and loss, impacting suitable habitats for endangered and rare species. This study was conducted to assess suitable habitats for the endangered oriental white stork in the wetland ecosystem of northeast China, to facilitate successful species-habitat conservation. The study incorporated field surveys, literature reviews, vegetation index calculations, eDNA for assessing prey abundance and land use and land cover classification for the years 2000, 2011, and 2022. A fuzzy logic-based habitat model was developed to map suitable habitats for the oriental stork. Generalized Linear Models (GLM) and Principal Component Analysis (PCA) were used to assess the influence of various environmental variables on habitat suitability changes. Roosting locations of the oriental stork were used as reference points to evaluate the impact of environmental factors on habitat suitability. The results indicate that 20% of the area is highly suitable for the stork, 73.4% is moderately suitable, and 5.6% is less or not suitable. Habitats near lakes and rivers, with low Normalized Difference Vegetation Index (NDVI) and high Normalized Difference Water Index (NDWI), are more suitable compared to areas close to roads and built-up zones. Prey abundance, particularly fish, is a crucial determinant of oriental stork presence and survival. Marshlands, swamps, and water bodies were identified as the most suitable habitats, as they interface with lotic and lentic ecosystems providing abundant prey for the storks. Our findings emphasize the importance of ongoing efforts to protect wetland ecosystems and habitats for endangered and rare bird species. Priority should be given to habitats identified as critical roosting areas for the oriental stork.

SALINITY-Induced Changes in Diversity, Stability, and Functional Profiles of Microbial Communities in Different Saline Lakes in Arid Areas

Saline lakes, characterized by high salinity and limited nutrient availability, provide an ideal environment for studying extreme halophiles and their biogeochemical processes. The present study examined prokaryotic microbial communities and their ecological functions in lentic sediments (with the salinity gradient and time series) using 16S rRNA amplicon sequencing and a metagenomic approach. Our findings revealed a negative correlation between microbial diversity and salinity. The notable predominance of Archaea in high-salinity lakes signified a considerable alteration in the composition of the microbial community. The results indicate that elevated salinity promotes homogeneous selection pressures, causing substantial alterations in microbial diversity and community structure, and simultaneously hindering interactions among microorganisms. This results in a notable decrease in the complexity of microbial ecological networks, ultimately influencing the overall ecological functional responses of microbial communities such as carbon fixation, sulfur, and nitrogen metabolism. Overall, our findings reveal salinity drives a notable predominance of Archaea, selects for species adapted to extreme conditions, and decreases microbial community complexity within saline lake ecosystems.

Climatic and environmental changes since last deglaciation in the steppe region of northern China and their impact on early population survival patterns

The northern Chinese steppe is situated in the periphery of the East Asian Summer Monsoon and exhibits high sensitivity to variations in monsoon intensity and global climate change. Therefore, comprehending the climatic evolution history of this region is pivotal for elucidating early human civilization development. The research focuses on a fully enclosed crater lake located in the northern Chinese steppe by utilizing n-alkanes, total organic carbon (TOC), total nitrogen (TN) in lake sediments, based on AMS-14C dating analysis, the climatic and environmental evolution history of this region from the last deglaciation to the middle Holocene has been reconstructed, and the impact of climate change on the evolution of early human civilization is elucidated. The findings indicate that the EASM driven by summer solar radiation, exerts control over the climate and hydrology in the steppe region of northern China. Since the last deglaciation, the gradual warming and humidification of the climate environment have significantly enhanced the animal and plant resources, thereby establishing a solid foundation for the transition of early human populations in northern Chinese steppe from high-mobility hunter-gatherers to settled communities. Additionally, this climatic shift has provided an optimal backdrop for the emergence of primitive agriculture. The changes of stone tool assemblages unearthed at related sites also confirm the above views. However, the climate model underwent rapid changes during the period of 7.2–6.4 cal kyr BP, leading to the occurrence of extreme arid climate events. Consequently, regional precipitation decreased, lake ecology became imbalanced, woody plants retreated in the basin, and vegetation coverage was greatly reduced. The aforementioned factor may have played a pivotal role in the disappearance of early populations within the region. Consequently, climate and environmental change not only serve as the primary driving force behind human civilization’s development but also act as an inexorable catalyst for its decline.