This study aims to identify phytoplankton diversity within the estuarine plume as an indicator of productivity in the Musi-Banyuasin Estuary. The research design integrates field observations with spatial analysis of Sentinel-2 imagery across five stations to provide a comprehensive map of water quality dynamics. Key numerical results reveal a contrasting environmental gradient. Station ME2 recorded the highest total suspended solids (TSS) concentration at 102 mg L-1 and chlorophyll-a at 5.75 mg m-3, while Station MB0 exhibited massive phytoplankton abundance reaching 909,395 cells m-3, dominated by Bacillariophyceae (98.85%). Diatom genera such as Chaetoceros, Skeletonema, Thalassionema, and Bacteriastrum constitute the main components, with Chaetoceros being the most dominant taxon, reaching a total abundance of 130,092,004 cells m-3. These findings indicate that high TSS concentrations at the river mouth act as a primary limiting factor through light-entry mechanisms, where extreme turbidity of up to 112 FTU inhibits light penetration for photosynthesis, thereby suppressing chlorophyll-a concentrations despite abundant nitrate levels (0.364 mg L-1). Conversely, in the transition zone with salinities of 23-30 ppt and alkaline pH (7.88-8.70), a gradual decrease in suspended solids triggers a surge in phytoplankton biomass. This study emphasizes that the estuarine plume dispersal mechanism functions as a biogeochemical regulator, determining primary productivity zonation through the antagonistic interaction between nutrient enrichment and optical interference caused by sediment suspension. The limitation of this research lies in its data dependence on seasonal river discharge fluctuations, which cause dynamic shifts in plume boundaries, necessitating more intensive temporal monitoring. The practical value of this study provides a strategic foundation for coastal management in mitigating the impacts of sedimentation on food chain stability. The originality of this study is underscored by the integration of Sentinel-2 data with the first in-situ observations at this location, offering new significance in understanding the ecological function of estuaries as biomass accumulation areas and natural pollutant filters for marine ecosystems.
Coexisting butterflies on the same host plant are potentially competitors and are excellent models for studying niche partitioning. To explore the niche partitioning mechanism of Sericinus montela and Atrophaneura alcinous sharing Aristolochia contorta in riverside habitats, we analyzed environmental factors associated with larval distribution through field surveys, and subsequently examined leaf quality, larval preference, and performance using A. contorta leaves grown under contrasting light conditions identified as the primary axis of partitioning in the field surveys. Field surveys revealed that relative light intensity (RLI) was the environmental variable significantly associated with the occurrence of both species in opposing directions: S. montela was found mainly in the lower riverbank with high RLI (odds ratio per %: 1.009, 95% confidence interval: 1.002-1.016), while A. alcinous was found in the upper riverbank with low RLI (odds ratio per %: 0.979, 95% confidence Interval: 0.973-0.986). Sunny leaves were nutritionally superior to shady leaves, and S. montela habitats also had greater leaf number per ramet, indicating that both the quantity and quality of food resources were favorable. In the bioassays, A. alcinous tended to prefer shady leaves, and although neither species differed in performance between leaf types, A. alcinous showed higher assimilation rate but lower relative growth rate and total leaf consumption than S. montela. These findings suggest that two specialist herbivorous butterflies sharing a single host plant can partition microhabitat along a small-scale light gradient, and that light environment heterogeneity generated by microtopography and vegetation structure contributes to maintaining niche partitioning between the two species. From a conservation perspective, removal of trees on upper slopes for riverside maintenance may disproportionately affect A. alcinous, which depends on shaded habitats, and the maintenance of small-scale light heterogeneity may therefore be an important consideration for managing conditions conducive to the coexistence of the two species.
Microplastic contamination in remote high-altitude ecosystems remains poorly understood, particularly for terrestrial birds acting as ecological indicators. Understanding contamination patterns in high-altitude avifauna is crucial for assessing local pollution, long-range atmospheric transport and ecosystem health in climate-sensitive mountain regions. This exploratory study examined microplastics in fecal samples in Tibetan Snowcock (Tetraogallus tibetanus), a bird species listed in CITES Appendix I, representing the first of its kind in high-altitude terrestrial birds. The research was carried out in Gokyo region of Sagarmatha (Mt. Everest) National Park, Nepal, to assess the ecological risk, characterize the morphological properties and understand conservation implications of microplastics. Seven fecal samples were collected non-invasively through an opportunistic sampling method. Sample analysis followed double digestion, density separation, centrifugation, visualization and measurements. Hot needle test was preferred as a confirmatory test. Of the seven samples, six contained microplastics, indicating ingestion and defecation of microplastics by Tibetan Snowcock. A total of 17 microplastic particles were identified, with fibres dominating at 94.12%, followed by fragments. Black particles were most common (47.06%), followed by blue (23.53%). The average dimensions of particles were 1,386 mm in length and 28 mm in width, with an aspect ratio of 61.4:1, pointing to textile-derived microfibers. Hierarchical clustering based on microplastic characteristics revealed three groups: colored particles; colorless, fibrous particles; and black, fragmented particles. These patterns suggest textile fibres transported through atmospheric pathways and fragmented plastics from degraded consumer products, likely due to localized pollution. There is low to moderate contamination with minor risk (microplastic pollution load index = 2.12) to such bird species in the eastern Himalayan region of Nepal. The high prevalence of contamination in this remote, protected ecosystem highlights significant microplastic pollution, raising urgent concerns for protecting its alpine biodiversity.
Ipomoea pes-caprae (L.) R. Br., a pantropical coastal vine species capable of long-distance oceanic dispersal, was recorded for the second time on Jeju Island, Korea, following the first record in 1985. Two non-flowering individuals were observed at the Sinyang coastal dune area on 9 September 2025. An analysis of oceanographic data (2016-2025) revealed significant warming trends in mean annual air (R2 = 0.36, p = 0.039) and sea surface (R2 = 0.37, p = 0.037) temperatures off Seogwipo. Winter sea surface temperatures (16.3-17.7°C) now exceed the thermal threshold for tropical species survival, indicating that Jeju Island’s coastal environment is becoming suitable for tropical and subtropical plant colonization. We propose that the reappearance of I. pes-caprae is not merely an episodic event but a biological indicator of the ongoing subtropicalization of Jeju Island’s coastal environment. Long-term monitoring is warranted to assess this species’ potential for naturalization and ecological impact under future warming scenarios.
Epiphytic orchids grow on host trees through a symbiotic relationship and are likely to be impacted by the characteristics and species of hosts. This study aims to explore the relationship between host trees and epiphytic orchids within the Panchase Forest Protection Area, central Nepal. The data were collected through a biophysical survey using a stratified random sampling method. The forest area was classified into three elevation zones: 1,000-1,500 m, 1,500-2,000 m, and 2,000-2,500 m using a 30 m SRTM dataset for accurate elevation data. A total of 40 sampling plots were established to examine the dynamics of host trees and epiphytic orchids across varying elevations and aspects. The diameter at breast height (DBH), height, and bark roughness of host trees, the distance from settlements, and the vertical distribution of orchids on host trees were recorded. Altogether, 51 epiphytic orchids were documented in 23 host trees. A considerable relationship between orchid species diversity and host tree diversity, as well as proximity to human settlements, was found. Host size, measured by height and DBH, had a significant influence on the distribution of orchid species. A positive correlation was observed between the number of orchid species and both the number of host species (p = 0.042) and the distance from human settlements (p = 0.045). Our findings show that large trees support more epiphytic orchids, and disturbances to them reduce orchid diversity. Finally, protecting host trees is crucial for conserving epiphytic orchid habitats and ensuring the survival of these ecologically important species.
Rising atmospheric CO2 is a primary driver of ongoing climate change; however, plant responses to elevated CO2 remain highly variable across species and functional traits. Given that CO2 enrichment fundamentally modulates photosynthesis, water-use efficiency, and growth, controlled experiments are essential to quantify these responses under climate-relevant conditions. In this context, open-top chambers (OTCs) provide a practical and standardized approach to simulate elevated CO2 environments in field settings. We describe a reproducible, low-cost OTC system and provide detailed protocols for its design, construction, calibration, and operation to facilitate widespread adoption. Performance validation confirmed that the system significantly elevated CO2 concentrations compared to ambient levels (targeting the RCP4.5 concentration of ~540 ppm), while maintaining consistent temperature and humidity profiles across chambers. As a case study, we compared the physiological responses of the endemic plant Leontopodium leiolepis and the widespread native plant Dendranthema zawadskii var. tenuisectum under ambient and elevated CO2 conditions. Elevated CO2 significantly increased leaf gas-exchange rates in both species, demonstrating that the developed OTC system is effective in inducing distinct physiological shifts in plants. However, morphological growth traits remained unchanged, with neither species showing significant plasticity between ambient and elevated CO2 conditions. Our OTC platform maintains environmental conditions while enabling precise regulation of CO2 concentrations. By simulating realistic future CO2 scenarios, the system effectively induces measurable physiological responses in plants, offering an accessible and reproducible framework for generating standardized trait datasets and empirically grounded sensitivity metrics.
Amphibians are sensitive to environmental change owing to their permeable skin and ectothermic nature. Frog calls can serve as bioindicators because call features and calling activity vary according to environmental factors. Treefrogs emit both advertisement and rain calls. Unlike advertisement calls, which are emitted at night and to attract mates, few studies have examined rain calls emitted during daytime. This study investigated the acoustic properties and seasonal calling patterns of Dryophytes japonicus rain calls, recorded in lowland woodlands near rice paddies. Rain calls occurred during daytime in both the breeding and nonbreeding seasons, whereas advertisement calls occurred exclusively after sunset during the breeding season. The rain calls had lower dominant frequencies, fewer notes, shorter note durations, and more rapid note repetition rates than advertisement calls. The calling activity for rain calls was significantly influenced by the time of day, air temperature, and humidity, regardless of the season. Unlike advertisement calls, rain calls are emitted during the daytime in the breeding and nonbreeding seasons, suggesting that they have specific functions and should be investigated in the future. Given the vocalizations of D. japonicus during the breeding and nonbreeding seasons, along with its pronounced sensitivity to environmental factors, the calling activity of D. japonicus may be used as a bioindicator of climate change.
Accurate estimation of genome size and determination of ploidy levels are fundamental for understanding plant genome architecture and their adaptive strategies in extreme environments. The Arctic region of Svalbard hosts a distinct vascular plant flora adapted to harsh climatic conditions, but comprehensive cytogenetic data remain scarce. This study compiles and analyzes chromosome numbers, ploidy levels, and genome sizes (C-values) for 185 plant taxa of Svalbard, providing essential baseline data for evolutionary and ecological research. Chromosome counts in Svalbard flora range from 2n = 10 to 270, with modal base numbers of x = 7 and x = 8. Polyploidy is widespread, with diploids representing 67 taxa followed by tetraploids, hexaploids, and higher even ploids. Genome sizes (1C-values) exhibit considerable variation both within and between families. Notably, chromosome number and genome size are decoupled in Cyperaceae and Poaceae, attributed to the difference of chromosome size. The prevalence of polyploid taxa is linked to increased genetic diversity and potential epigenetic mechanisms promoting survival in the Arctic's cold, nutrient-poor, and short growing season environments. This comprehensive cytogenetic dataset provides a critical foundation for ongoing and future studies on plant adaptation, evolution, and genome dynamics in Arctic ecosystems. The findings underscore the ecological importance of polyploidy and genome structural variation in shaping the resilience of polar flora under climatic stress and global change. These data will enhance molecular, ecological, and conservation research efforts in Svalbard and other high-latitude regions.
Public engagement is critical for environmental action, but its dynamics were disrupted by the COVID-19 pandemic. Whether this acute pandemic crisis eclipsed or paradoxically amplified long-term ecological concerns remains uncertain. Here, we analyze a massive (2014-2025) longitudinal social big data archive from Republic of Korea, comparing 18 ecological keywords pre- and post-pandemic. Our tripartite analysis reveals a complex restructuring, not a simple uniform shift. The pandemic suppressed public interest in 'fine dust' (83,481 ± 65,110 to 45,610 ± 19,525 mentions) while accelerating 'climate crisis' (185 ± 424 to 7,526 ± 3,741 mentions). Sentiment analysis showed a critical divergence: 'climate crisis' discourse became significantly more negative (57% to 38% positive), while 'microplastic' discourse became more positive (40% to 57%). Most profoundly, semantic network analysis revealed a structural "re-wiring." A sparse, fragmented pre-pandemic network was reorganized into dense clusters, forging a novel, dominant link between 'COVID virus' and 'fine dust' (public health-environment axis) and a new 'climate-action' cluster ('climate change,' 'carbon neutrality,' 'environmental movement'). The COVID-19 pandemic acted as a powerful semantic catalyst, fundamentally altering the cognitive landscape of public ecological perception. It did not just change what people discuss, but how they frame and connect issues. This transformation creates new opportunities for integrated policy (e.g., public health and environment) but also highlights persistent gaps, as fundamental and ecological functional concepts like 'food web' remain isolated from public discourse. These findings are critical for designing effective post-pandemic environmental communication.
Local environmental conditions shape forest biodiversity, while silvicultural practices like clear-cutting and retention harvesting can rapidly alter forest structure and microclimate, affecting ecosystem services. This study investigated the short-term impacts of logging practices, specifically clear-cutting and aggregated retention, on arthropod diversity and community structure in the Japanese larch forest in South Korea. Responses of arthropods to logging varied among taxa: Hemiptera and Coleoptera were abundant in logged areas, whereas Araneae and Formicidae in Hymenoptera were more abundant in unlogged areas than in logged areas. This variation underscores the challenge of assessing logging impacts using specific taxa alone. Multivariate analyses clearly distinguished the differences in arthropod communities between logged and unlogged areas. Our findings show that arthropod responses to logging vary among taxa, resulting in distinct community structures in logged and unlogged stands of Japanese larch forests. These short-term changes emphasize the importance of retention-based management for conserving arthropod communities.
Mercury (Hg) is a potent neurotoxin that can become biomagnified via food chains, leading to serious ecological and human health risks. However, despite national monitoring efforts in the Republic of Korea, the neurochemical effects of environmentally relevant Hg levels on freshwater fish remain unclear. Here, we investigate the total and organic Hg levels in 17 freshwater fish species from the Yeongsan River system in Korea, finding total concentrations of 39-1,423 ppb, with organic Hg accounting for 85.7% of this on average. Approximately 25% of specimens exceeded the US EPA consumption guidelines (0.3 ng g-1), indicating potential dietary exposure risks. A significant size-dependent increase in Hg was also observed in Lepomis macrochirus and Zacco platypus, while concentrations of Hg in the brain were negatively correlated with acetylcholinesterase activity. These findings indicate that ecologically consequential neurochemical changes occur following exposure to Hg at environmentally relevant levels and highlight the need for the continuous monitoring of Hg in freshwater ecosystems.
Forest clear-cutting is a strong disturbance that reshapes plant community structure and functional strategies. In this study, we aimed to examine how woody plant functional traits respond to clear-cutting and whether these responses retain phylogenetic signals or reflect phylogenetic niche conservatism. We measured seven functional traits related to leaf and stem characteristics for 841 individuals belonging to 80 taxa in clear-cut and control plots in southern Korea. Phylogenetic signals were tested using Blomberg's K and Pagel's λ. Meanwhile, local indicators of phylogenetic association and phylogenetic principal component analysis (PPCA) were applied to assess local patterns and multivariate trait-phylogeny relationships. The results showed significant trait shifts, including reduced specific leaf area and increased leaf dry mass and stem dry mass. However, most traits lost overall phylogenetic signals after clear-cutting. Meanwhile, Quercus spp. and Rhododendron spp. exhibited significant local phylogenetic signals, indicating convergent responses among close relatives. PPCA showed no clear separation between clear-cut and control plots, yet could be distinguished between tree and shrub species along key trait axes. These findings suggest that strong disturbances weaken phylogenetic niche conservatism at the community level. Meanwhile, local phylogenetic structures and pre-adaptation shape early recovery pathways. Our study highlights the importance of integrating trait-based and phylogenetic approaches for forest restoration and long-term monitoring.
Background: This study investigates the impact of flooding rate and bank type on plant species composition in riparian wetlands. Riparian wetlands, which are connected to rivers, provide a unique ecological environment shaped by periodic flooding and water flow, supporting diverse flora and fauna. The flooding rate directly influences plant community structure; flood-tolerant species dominate frequently flooded areas, whereas other species thrive in less frequently flooded zones. Bank type affects soil moisture distribution, influencing plant composition and growth. Soil characteristics were analyzed, and vegetation was surveyed across the upper, middle, and lower sections of banks at 30 sites along the Han River in Korea. Results: The study found that the upper sections of banks where water flows down from the land maintained higher soil moisture content, favoring the dominance of moisture-tolerant species such as Phragmites australis and Humulus japonicus, which consequently reduced species diversity. In contrast, the upper sections of banks with levees that restricted water flow exhibited relatively lower soil moisture content, reducing the prevalence of dominant species such as H. japonicus and P. australis and thereby promoting higher species diversity. Most environmental factors showed no significant differences between the two bank types, except for soil moisture content in the upper section and soil organic matter content and pH in the lower section, which exhibited statistically significant variations (p < 0.05). Soil moisture content, pH, soil organic content, and soil texture were identified through redundancy analysis as key environmental variables influencing plant distribution, with each species responding uniquely to the hydrological and soil conditions shaped by flooding rate and bank type. Conclusions: This study highlights the need for effective levee design and wetland management strategies to promote biodiversity and maintain ecological balance in floodplain ecosystems.
Background: Parasitic mistletoes infect a wide range of host plants, and when infestation density is high, they alter host resource allocation and canopy structure, thereby affecting ecosystem components including light regimes and understory vegetation. In South Korea, research has primarily focused on their bioactive properties, with limited attention to host associations or ecological traits. This study examined the host plant diversity and preference of Korthalsella japonica (Thunb.) Engl. and predicted its potential habitats to provide baseline data for conservation planning. Results: Korthalsella japonica was found on 26 host species belonging to 11 families and 18 genera, including 15 newly recorded host plants. A clear preference for warm-temperate evergreen broad-leaved trees was observed, particularly Eurya japonica Thunb. and Camellia japonica L. This pattern indicates that host selection is shaped not only by parasitic opportunism but also by physiological compatibility and the spatial structure of densely distributed evergreen assemblages. Predicted suitable habitats were primarily concentrated in gently sloping areas near streams within the lower mid-mountainous regions of Jeju Island, aligning well with actual vegetation structures and host plant distributions. Conclusions: The distribution of K. japonica reflects an intermediate level of host specificity, closely associated with warm-temperate evergreen broad-leaved forests. These findings advance understanding of the ecology of K. japonica by revealing its host diversity, habitat preferences, and key environmental determinants, and they provide valuable baseline data to guide future conservation planning and management strategies.
