Ecological integration of Vespa velutina Lepeletier, 1836 in South Korea: a comprehensive study of co-occurrence and interaction patterns with native social wasps.

BACKGROUND: The spread of Vespa velutina Lepeletier, 1836 (Asian hornet) in South Korea poses a threat to biodiversity and agriculture. Traditional species interaction models often fail to capture the complexity of invasive species dynamics. This study used association rule learning (ARL) and clustering analyses to explore the interactions of V. velutina with native Vespidae species in South Korea, with the aim of uncovering patterns of coexistence and competition. RESULTS: Over 4 years (2020-2023), 304 traps were strategically placed across South Korea to collect data on Vespidae species. Our findings showed that Vespula flaviceps, Vespa crabro, and Vespula koreensis were the most frequently encountered species. V. velutina was also widespread, suggesting its successful integration into local ecosystems. The ARL analysis, using the 'apriori' algorithm, identified significant co-occurrence patterns and potential interactions. The rules generated indicated both competitive and coexistent relationships with varying levels of association strength across different regions. Clustering analyses, including hierarchical and k-means clustering, grouped species based on their occurrence similarities. The distinct clusters formed in the analysis highlighted the unique ecological roles and interactions of V. velutina and other Vespidae species in South Korean ecosystems. CONCLUSION: This study confirms the successful establishment of V. velutina in diverse South Korean ecosystems and highlights its complex interactions with native species. These findings support the need for nuanced management strategies that consider the intricate ecological relationships of V. velutina. This approach is crucial for the effective management of invasive species and ecosystem conservation. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Developmental temperature modulates microplastics impact on amphibian life history without affecting ontogenetic microplastic transfer.

This study examines how temperature influences the response of Japanese tree frogs (Dryophytes japonicus) to microplastic (MP) pollution, assessing whether temperature can regulate the harmful effects of MPs on their life history and the dispersal of MPs across habitats. This analysis aims to understand the ecological and physiological ramifications of MP pollution. Our results demonstrated an ontogenetic transfer of MP particles across amphibian metamorphosis, possibly allowing and facilitating the translocation of MPs across ecosystems. Temperature did not significantly affect the translocation of aquatic MPs to land. However, high temperatures significantly reduced mortality and hindlimb deformities caused by MPs, thereby mitigating their harmful impact on amphibian life histories. Importantly, our study found that MPs cause hindlimb deformities during amphibian metamorphosis, potentially linked to oxidative stress. Additionally, MP exposure and ingestion induced a plastic response in the morphology of the digestive tract and changes in the fecal microbiome, which were evident at high temperatures but not at low temperatures. The effects of MPs persisted even after the frogs transitioned to the terrestrial stage, suggesting that MPs may have complex, long-term impacts on amphibian population sustainability. Our results enhance the understanding of the intricate environmental challenges posed by MPs and underscore the significant role of temperature in ectotherms regarding ontogenetic impacts and pollutant interactions.

Combined effect of seasons and life history in an anuran strengthens the response and relationship between their physiology and gut microbiota.

Gut microbiota impact host physiology, though simultaneous investigations in ectothermic vertebrates are rare. Particularly, amphibians may exhibit more complex interactions between host physiology and the effects of gut microbiota due to the combination of seasonal changes and complex life histories. In this study, we assessed the relationships among food resources, gut bacterial communities, and host physiology in frogs (Phelophylax nigromaculatus), taking into account seasonal and life history variations. We found that food sources were not correlated with physiological parameters but had some relationships with the gut bacterial community. Variations in gut bacterial community and host physiology were influenced by the combined effects of seasonal differences and life history, though mostly driven by seasonal differences. An increase in Firmicutes was associated with higher fat content, reflecting potential fat storage in frogs during the non-breeding season. The increase in Bacteroidetes resulted in lower fat content in adult frogs and decreased immunity in juvenile frogs during the breeding season, demonstrating a direct link. Our results suggest that the gut microbiome may act as a link between food conditions and physiological status, and that the combined effect of seasons and life history could reinforce the relationship between gut microbiota and physiological status in ectothermic animals. While food sources may influence the gut microbiota of ectotherms, we contend that temperature-correlated seasonal variation, which predominately influences most ectotherms, is a significant factor.

Application of citizen science with the nationwide bird census.

Citizen science (CS) is the most effective tool for overcoming the limitations of government and/or professional data collection. To compensate for quantitative limitations of the 'Winter Waterbird Census of Korea', we conducted a total of four bird monitoring via CS from 2021 to 2022. To use CS data alongside national data, we studied CS data quality and improvement utilizing (1) digit-based analysis using Benford's law and (2) comparative analysis with national data. In addition, we performed bird community analysis using CS-specific data, demonstrating the necessity of CS. Neither CS nor the national data adhered to Benford's law. Alpha diversity (number of species and Shannon index) was lower, and total beta diversity was higher for the CS data than national data. Regarding the observed bird community, the number of species per family was similar; however, the number of individuals per family/species differed. We also identified the necessity of CS by confirming the possibility of predicting bird communities using CS-specific data. CS was influenced by various factors, including the perceptions of the survey participants and their level of experience. Therefore, conducting CS after systematic training can facilitate the collection of higher-quality data.

Gut microbiome diversity and function during hibernation and spring emergence in an aquatic frog.

The gut microbiota maintains a deeply symbiotic relationship with host physiology, intricately engaging with both internal (endogenous) and external (exogenous) factors. Anurans, especially those in temperate regions, face the dual challenges of significant external influences like hibernation and complex internal variances tied to different life histories. In our research, we sought to determine whether different life stages (juvenile versus adult) of the Japanese wrinkled frog (Glandirana rugosa) lead to distinct shifts in gut bacterial communities during winter (hibernation) and its subsequent transition to spring. As hypothesized, we observed a more pronounced variability in the gut bacterial diversity and abundance in juvenile frogs compared to their adult counterparts. This suggests that the gut environment may be more resilient or stable in adult frogs during their hibernation period. However, this pronounced difference was confined to the winter season; by spring, the diversity and abundance of gut bacteria in both juvenile and adult frogs aligned closely. Specifically, the variance in gut bacterial diversity and composition between winter and spring appears to mirror the frogs' ecological adaptations. During the hibernation period, a dominance of Proteobacteria suggests an emphasis on supporting intracellular transport and maintaining homeostasis, as opposed to active metabolism in the frogs. Conversely, come spring, an uptick in bacterial diversity coupled with a dominance of Firmicutes and Bacteroidetes points to an upsurge in metabolic activity post-hibernation, favoring enhanced nutrient assimilation and energy metabolism. Our findings highlight that the relationship between the gut microbiome and its host is dynamic and bidirectional. However, the extent to which changes in gut bacterial diversity and composition contribute to enhancing hibernation physiology in frogs remains an open question, warranting further investigation.

The difference and variation of gut bacterial community and host physiology can support adaptation during and after overwintering in frog population.

The hibernation of amphibians can offer a unique window into overwintering adaptation processes and host-gut microbiota interactions through changes in metabolic availability and homeostasis. We attempted to identify differences in the physiology and gut microbiome during and after hibernation in Japanese wrinkled frogs (Glandirana rugosa), an aquatic overwintering amphibian. After hibernation, the high alpha and beta diversity of the gut bacterial community appears to reflect the more diverse and complex environmental conditions. During winter, Proteobacteria dominated the majority of the gut bacterial community, likely due to high oxygen saturation. After hibernation, Firmicutes and Bacteroidetes increased, which are supportive of host metabolism by gut microbiota. Corticosterone also showed high values and variances after hibernation, presumably allowing the population to remain adaptable across a broad range of environmental gradients. Innate immunity was high after hibernation but exhibited low variation among populations, which supports the idea of a prioritized investment in immunity after hibernation. Blood biochemistry suggests that aquatic overwintering frogs have a mechanism to adapt through overhydration and regulate homeostasis through water excretion associated with the kidney and urine after hibernation. Frog populations exhibit variations and adaptability in gut microbiota and physiology during and after hibernation: Through this, they may demonstrate an adaptive response that regulates metabolic availability in preparation for unpredictable environmental changes. We also propose that the maintenance of Proteobacteria during hibernation can support the colonization of Firmicutes and Bacteroidetes after hibernation, underscoring the need to study the complex effects of gut microbiota across multiple life stages.

Tadpole growth rates and gut bacterial community: Dominance of developmental stages over temperature variations.

Tadpoles present an intriguing model system for studying the regulation and selection of gut microbiota. They offer a unique perspective to enhance our understanding of host-microbiota interactions, given their capacity to alter the dynamics of the gut microbial community by interacting with multiple environmental factors within a complex life cycle. In this study, we comprehensively investigated variations in growth rate and gut bacterial community in relation to temperature differences during the complex process of amphibian metamorphosis. Higher temperatures prompted tadpoles to metamorphose more rapidly than at lower temperatures, but the impact on size and weight was minimal. Differences in temperature were not associated with gut bacterial diversity, but they did affect certain aspects of beta diversity and bacterial composition. However, the developmental stage invoked greater heterogeneity than temperature in gut bacterial diversity, composition, and functional groups. These findings suggest that inherent biological systems exert stronger control over an organism's homeostasis and variation than the external environment. Although results may vary based on the magnitude or type of environmental factors, metamorphosis in tadpoles greatly influences their biology, potentially dominating microbial interactions.

Current State of Conservation Physiology for Amphibians: Major Research Topics and Physiological Parameters.

Analysis of physiological responses can be used to assess population health, identify threat factors, and understand mechanisms of stress. In addition to this, conservation physiologists have sought to establish potential management strategies for environmental change and evaluate the effectiveness of conservation efforts. From past to present, the field of conservation physiology is developing in an increasingly broader context. In this review, we aim to categorize the topics covered in conservation physiology research on amphibians and present the measured physiological parameters to provide directions for future research on conservation physiology. Physiological responses of amphibians to environmental stressors are the most studied topic, but conservation physiological studies on metamorphosis, habitat loss and fragmentation, climate change, and conservation methods are relatively lacking. A number of physiological indices have been extracted to study amphibian conservation physiology, and the indices have varying strengths of correlation with each subject. Future research directions are suggested to develop a comprehensive monitoring method for amphibians, identify interactions among various stressors, establish physiological mechanisms for environmental factors, and quantify the effects of conservation activities on amphibian physiology.

Microsatellite Dataset for Cultivar Discrimination in Spring Orchid (Cymbidium goeringii).

Cymbidium goeringii Reichb. fil., locally known as the spring orchid in the Republic of Korea, is one of the most important and popular horticultural species in the family Orchidaceae. C. goeringii cultivars originated from plants with rare phenotypes in wild mountains where pine trees commonly grow. This study aimed to determine the cultivar-specific combined genotypes (CGs) of short sequence repeats (SSRs) by analyzing multiple samples per cultivar of C. goeringii. In this study, we collected more than 4000 samples from 67 cultivars and determined the genotypes of 12 SSRs. Based on the most frequent combined genotypes (CG1s), the average observed allele number and combined matching probability were 11.8 per marker and 3.118 × 10-11, respectively. Frequencies of the CG1 in 50 cultivars (n ≥ 10) ranged from 40.9% to 100.0%, with an average of 70.1%. Assuming that individuals with the CG1 are genuine in the corresponding cultivars, approximately 30% of C. goeringii on the farms and markets may be not genuine. The dendrogram of the phylogenetic tree and principal coordinate analysis largely divided the cultivars into three groups according to their countries of origin; however, the genetic distances were not great among the cultivars. In conclusion, this dataset of C. goeringii cultivar-specific SSR profiles could be used for ecogenetic studies and forensic authentication. This study suggests that genetic authentication should be introduced for the sale of expensive C. goeringii cultivars. We believe that this study will help establish a genetic method for the forensic authentication of C. goeringii cultivars.

Gut bacterial diversity in Vespa velutina and implications for potential adaptation in South Korea.

BACKGROUND: Invasive species such as the yellow-legged hornet (Vespa velutina), along with four other Vespa species - Vespa analis, Vespa crabro, Vespa ducalis, and Vespa mandarinia - pose significant threats to the environment, economy, and human health. This study focuses on understanding the key factors contributing to the successful invasion of these species, particularly V. velutina, in South Korea. The analysis encompasses the gut bacterial communities and stable isotopes of carbon and nitrogen of the queen hornets, aiming to identify variances in gut microbial composition and food resource utilization. RESULTS: The gut bacterial communities in the five Vespa species were primarily composed of Proteobacteria, with Firmicutes and Bacteroidetes present. Vespa velutina and V. mandarinia had higher Firmicutes abundance at the phylum level, possibly indicating an increased capacity for dietary fiber breakdown and short-chain fatty acid production, providing them with a competitive edge. No significant differences in nitrogen and carbon stable isotope values were found among the five Vespa species, suggesting that they fed on similar food sources. However, V. velutina had a higher number of unique gut bacterial operational taxonomic units (OTUs), implying adaptation through the acquisition of a distinct gut bacterial set. Significant correlations were found between the observed index and the Shannon index, and between δ15 N and the observed index, suggesting that the food source diversity may influence the gut bacterial community diversity. CONCLUSION: Our study offered valuable insights regarding the adaptation of V. velutina to its new environment in South Korea. The potential role of gut microbiota in the success of invasive species was elucidated. This information is crucial for the management of invasive species, targeted control methods, and implementing preventive regulations. Further studies with larger sample sizes and comprehensive sampling are required to gain a complete understanding of the gut microbiota of Vespa species and their adaptation to new environments. © 2023 Society of Chemical Industry.

Seasonal Pattern of Advertisement Calling and Physiology in Prolonged Breeding Anurans, Japanese Tree Frog (Dryophytes japonicus).

The calling behavior of anurans should be studied in detail as it greatly influences their physiology and immunity, particularly in prolonged breeding species. The effect can be further complicated by the emergence timing in the breeding season. We conducted a study comparing the physiology and calling behavior of the Japanese tree frog (Dryophytes japonicus), a prolonged breeder species, according to the breeding timing. During the middle of the breeding season, a high chorus size appeared, indicating a breeding peak. However, chorus size did not dominate physiology and calling behavior. In the early breeding season, frogs had a high energy storage state and immunity. In the middle of the breeding season, individuals from the early breeding season were considered to have exhausted their energy stores and had low immunity. Towards the end of the breeding season, frogs appeared to have newly introduced, at which time energy stores and immunity were as high as in the beginning. However, unlike the physiology, the pattern of calling constantly varied as the breeding season progressed. Frogs from the early season conserved energy used for calling, and frogs from the late season showed a breeding spurt for mating. Our results can help in understanding the energy metabolism of calling behavior, physiology, and disease epidemiology in prolonged breeder species. They also suggest that individuals coordinate their participation in the breeding season and that the timing of their appearance at breeding sites may not be random.

Phenotypic Plasticity in Juvenile Frogs That Experienced Predation Pressure as Tadpoles Does Not Alter Their Locomotory Performance.

Anuran species can respond to environmental changes via phenotypic plasticity, which can also result in ecological impacts across the life history of such species. We investigated the effects of predation pressure (i.e., the non-consumption effect) from the dragonfly larva (Anax parthenope) on the phenotypical change of tadpoles into juvenile frogs (specifically the black-spotted pond frog, Pelophylax nigromaculatus), and also analyzed the impact of morphological changes on locomotory performance after metamorphosis. The experiments on predator impact were conducted in the laboratory. Body length, weight, development timing, and metamorphosis timing in the presence of dragonfly nymphs were measured in both tadpoles and juvenile frogs. The body and tail shapes of the tadpoles, as well as the skeletal shape of the juvenile frogs, were analyzed using landmark-based geometric morphometrics. Furthermore, the locomotory performance of the juvenile frogs was tested by measuring their jumping and swimming speeds. Tadpoles that had grown with predators possessed smaller bodies, deeper tail fins, and slower development rates, and they waited longer periods of time before commencing metamorphosis. Having said this, however, the effect of predator cues on the body length and weight of juvenile frogs was not found to be significant. These juvenile frogs possessed longer limbs and narrower skulls, with subtle morphological changes in the pelvis and ilium, but there was no subsequent difference in their swimming and jumping speeds. Our results showed that the changes in anatomical traits that can affect locomotor performance are so subtle that they do not affect the jumping or swimming speeds. Therefore, we support the view that these morphological changes are thus by-products of an altered tadpole period, rather than an adaptive response to predator-escape ability or to post-metamorphosis life history. On the other hand, delayed metamorphosis, without an increase in body size, may still be disadvantageous to the reproduction, growth, and survival of frogs in their life history following metamorphosis.

The Gut Bacterial Community of Chlaenius pallipes (Coleoptera: Carabidae) Associates with Their Habitat and Morphology.

We investigated whether the gut bacterial community of Chlaenius pallipes could represent the health conditions of individuals or populations based on where these beetles inhabit. Considering the ecological traits of the species, the gut bacterial communities of carabid populations inhabiting stable or unstable habitats were compared. Food resource quality (δ15N) and morphological shape, especially body and wing size, may be significant factors that directly or indirectly affect the gut bacterial community of carabid beetles. Firmicutes (51.7%) and Proteobacteria (36.3%) were the predominant phyla in the gut bacterial community of C. pallipes. A significant difference in the gut bacterial community structure was observed between organisms inhabiting unstable and stable habitats in this study. Wing size, as estimated by centroid size, was correlated with differences in the gut bacterial community composition of the species. Even if a factor is not strong enough to determine the survival of carabid beetles, the composition of the gut bacterial community can change. We found that although each individual has a large variation in the gut bacterial community composition, the gut bacterial community can be used to evaluate the condition of each habitat through consistent investigation. Habitat assessment based on changes in the number of carabid beetle species and their composition requires relatively long-term research; however, the gut bacterial community of carabid beetles can help identify short-term environmental changes.

Wind Turbine Noise Behaviorally and Physiologically Changes Male Frogs.

As the advantages of wind energy as an eco-friendly strategy for power generation continue to be revealed, the number of offshore wind farms also increases worldwide. However, wind turbines can induce behavioral and physiological responses in animals by emitting various types of noises. In this study, we investigated the behavioral, physiological, and immunological responses of male Japanese tree frogs (Dryophytes japonicus) when exposed to wind turbine noise. To determine the effects during the breeding season, frogs were collected from areas with and without wind turbines. Additionally, we exposed the frogs to recorded wind turbine noise at a site without a wind generator for 1 h to 24 h to analyze the short-term effects. Three types of calling patterns (dominant frequency, note duration, and call rate) were analyzed to investigate behavioral responses. Physiological responses were assessed using two steroid hormones assays, namely testosterone and corticosterone detection in the saliva. The immunity of each individual was assessed using a bacterial killing assay. The wind turbine group in the field had a higher call rate and corticosterone levels and lower immunity than the group in the field without turbines present, and all three of these variables were correlated with each other. Conversely, in the noise exposure experiment, a higher call rate was only observed post-exposure compared to pre-exposure. Thus, turbine noise seems to induce decreased immunity in Japanese tree frogs as an increase in energy investment that triggers a behavioral response rather than acting as a sole physiological response that leads to a direct increase in corticosterone. This decreased immunity due to energy tradeoff or physiological response can change the disease epidemiology of the population and create new adaptive patterns in these habitats.

Development of a preliminary environmental risk assessment system by using text mining for introducing alien crops.

Changes in worldwide crop trends and climate change has increased the introduction of alien crops. However, there are always potential side effect issues related to introduced crops, such as the introduced crop becoming a nuisance at the new country or bringing insect pests or microorganisms with the introduced crops. In this study, we developed a crop introduction risk assessment system using text mining method to prevent this problem. First, we designed the "Preliminary Environmental Impact Assessment Index for Alien Crops" based on ecological researches to assess the risks of introduced crops to the natural environment. The questionaries evaluate the target alien crop with previous cases reporting the target crops' adverse effects on the environment, the potential of target crops' direct or indirect damage on the environment. The index has sixteen questions with allocated scores that are divided into 4 categories. The detailed rationales of the questionaries and the assessment index are discussed in main text. Second, we assessed 67 crop species that were introduced or scheduled to be introduced to South Korea with this Preliminary Assessment Index. The literature and data were collected with JabRef, search engines, and from the documents of six international institutions. Finally, based on the preliminary assessment results of selected species, we developed the protocols and a manual for the preliminary environmental risk assessment of introduced species. Final evaluation scores for risk evaluation for introducing crops are suggested (over 70 total score for 'danger' and over 50 points for 'caution required', and under 50 points for 'low expected impact'). Presented crop introduction risk assessment system is effective to identify potential problem making crop species. The protocols and a manual that we provide in this study could be applied to other countries which have similar climate and environmental conditions, or after being adequately modified to their environmental factors such as climate, neighboring countries, major crops according to eating habits, and major vegetation.

Genetic and morphological variation of Vespa velutina nigrithorax which is an invasive species in a mountainous area.

The yellow-legged hornet (Vespa velutina nigrithorax) is an invasive species in South Korea with negative economic, ecological, and public health impacts. We investigated genetic and morphological variation in the species populations on Mt. Jiri, the tallest mountain in South Korea. We hypothesized that a high-altitude would be negatively correlated with the genetic diversity of the hornet population, and hornet wing morphology would change with an increase in altitude. Our results showed that the genetic diversity of yellow-legged hornets did not decrease as altitude increased. Regardless of the altitude, the inbreeding coefficient was high at the newly colonized sites. A single genetic population occurred in the mountainous areas examined and gradually expanded its range. Wing morphology, especially shape, did not change with an increase in altitude or decrease in temperature. Although snow cover and cool temperatures at high altitudes could limit nest-building activities, they did not prevent the extension of the range of the species. Therefore, the yellow-legged hornet cannot be controlled naturally by climate or topography; combined approaches, including chemical control, nest removal, and bait-trapping techniques should be implemented.

Examination of Physiological and Morphological Differences between Farm-Bred and Wild Black-Spotted Pond Frogs (Pelophylax nigromaculatus).

Due to the decline in the population and the difficulty of in situ conservation, several anuran species are being reared in captivity. In this study, we identified physiological and morphological differences between farm-bred and wild frogs. Nine different serum components were used as indicators of osmotic pressure, homeostatic state, organ function, and nutritional status of farm-bred frogs and wild frogs, while radiographic techniques were used to visualize differences in bone mineral density and body composition ratio. Additionally, X-ray skeletal images were used for morphological analysis to estimate differences in locomotory performance between the two groups. Wild frogs harbor traits that aid in better locomotory performance than farm-bred frogs. They also have a relatively lower fat content ratio and higher calcium and phosphorus serum levels than farm-bred frogs, suggesting a difference in nutritional status. However, hepatic stress was higher in wild frogs than in farm-bred frogs. Veterinary clinical examinations allow for the identification of differences in nutritional and morphological conditions between farm-bred and wild frogs. Determining the health of animals can help improve their living conditions, eliminate conditions that can negatively affect them, and effectively manage them on farms, in zoos, and at ex situ conservation institutes.

Reference Intervals in Combined Veterinary Clinical Examinations of Male Black-Spotted Pond Frogs (Pelophylax nigromaculatus).

In conservation physiology, analyzing the physiological response of an organism to understand its ability to adapt to environmental changes is a key technique in establishing a successful conservation strategy. Veterinary clinical examinations determine the physiological condition of animals accurately and safely, and this examination is synergistic when combined. The accuracy and safety of a clinical examination makes it advantageous for use in amphibians with high species diversity and numerous endangered species. However, it is necessary to establish a reference interval (RI) for precise interpretations and identification of animals with abnormalities through individual unit testing. We have established RIs for the immunity, serum components, bone mineral density (BMD), and body composition of black-spotted pond frogs (Pelophylax nigromaculatus). Black-spotted pond frogs are a common species and are widely distributed in East Asia, with suitable characteristics for environmental monitoring. Serum was extracted from 151 male frogs to establish the RI for bacterial killing ability in order to represent immunity. We also used the serum to establish an RI of ten additional serum components to determine the nutritional status, organ function status, body osmotic pressure, and homeostasis conditions. The BMD and three body composition measures for diagnosing food intake status and nutritional condition were measured using dual energy X-ray absorptiometry. The RI was recorded as the mean ± standard deviation, median, first (25%) to third (75%) quantile range, 95% confidence interval of the mean and median, and the 95% percentile (2.5%-97.5% range) of all components. The use of combined clinical veterinary examinations aids our understanding of the physiological conditions of an individual according to biotic and abiotic factors on a complex spatiotemporal scale in an ecosystem.

Physiological Response of Pelophylax nigromaculatus Adults to Salinity Exposure.

Many freshwater ecosystems are becoming more saline, and amphibians, which have permeable skin, are sensitive to this change. We studied the physiological responses to high salinity and recovery from saline exposure in adult frogs (Pelophylax nigromaculatus). Frogs that experienced severe salinity were exposed to saline conditions for 6 days, while those in the moderate group were exposed to saline conditions for 40 days, followed by a recovery period in freshwater for 20 days. Our data showed that during exposure to saline conditions of severe and moderate groups, serum electrolytes increased, protein concentrations decreased, and creatinine, an indicator of renal function, sharply increased. However, renal tissue sampled after exposure did not show renal dysfunction. In addition, serum components that changed during exposure to salinity returned to their initial values during the recovery period. Thus, adult anurans can be resilient, to some extent, to saline conditions in habitats that experience either rapid or slow salinity changes.

Evaluating the physical condition of Hyla japonica using radiographic techniques.

Amphibian populations are declining throughout the world, which has negatively impacted various organisms and ecosystems. The goal of this study was to obtain a better understanding of the physiological status and condition of individuals in amphibians is needed to preserve these groups. We used radiography to assess physical conditions in Hyla japonica frogs, which are widely distributed in East Asia. Bone images were examined to determine fractures and metabolic bone disease of frogs in a wild population. The bone-mineral density (BMD), stable nitrogen isotope ratio (δ15N), and physical conditions (body length, age, and body weight) and body compositions (fat mass and lean mass) were measured to identify changes correlating with the food-intake status. To analyze the physiological and morphological effects of predation pressure in H. japonica, we compared the BMD, food-intake status, physical conditions, body compositions and skeletal shape in H. japonica between populations with Lithobates catesbeianus (paddy fields with bullfrogs; PB) and without L. catesbeianus (no bullfrogs; NB). Only five of 101 H. japonica frogs had fractures, and no bone disease due to malnutrition was found. The food-intake status correlated with the BMD, but not to the other physical conditions and body compositions measured. Similarly, the BMD and δ15N of the NB group were higher than those of the PB group, but the other physical conditions and body compositions were not different. The skeletal shapes of the head and lower body were not significantly different between the two groups. Our findings revealed that the BMD can be used to determine the food-intake status and be changed in by predation pressure. We suggest using the BMD of anurans to estimate physiological changes that occur in response to the habitat or biological interactions.