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Climate change and human activities escalate the frequency and intensity of wildfires, threatening amphibian habitats and survival; yet, research on these impacts remains limited. Wildfire ash alters water quality, introduces contaminants, and may disrupt microbial communities, impacting gut and skin microbiota; however, the effects on gut and skin microbiota remain unclear. Rana dybowskii were exposed to five concentrations (0 g L -1 , 1.25 g L -1 , 2.5 g L -1 , 5 g L -1 , and 10 g L -1 ) of aqueous extracts of wildfire ashes (AEAs) for 30 days to assess AEAs' metal content, survival, and microbiota diversity via Illumina sequencing. Our results showed that the major elements in ash were Ca > K > Mg > Al > Fe > Na > Mn, while in AEA they were K > Ca > Na > Mg > As > Al > Cu. A significant decrease in amphibian survival rates with increased AEA concentration was shown. The beta diversity analysis revealed distinct shifts in microbiota composition. Notably, bacterial genera associated with potential health risks showed increased abundance in skin microbiota, emphasising the potential for ash exposure to affect amphibian health. Functional prediction analyses revealed significant shifts in metabolic pathways related to health and disease, indicating that wildfire ash exposure may influence amphibian health through changes in microbial functions. This study highlights the urgent need for strategies to mitigate wildfire ash impacts on amphibians, as it significantly alters microbiota and affects their survival and health., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Rice straw is burned as a result of agricultural practices and technical limitations, generating significant volumes of ash that might have environmental and ecological consequences; however, the effects on organisms have not been researched. Amphibians depend on their gut and skin microbiomes. Ash exposure may cause inflammation and changes in microbial diversity and function in frogs' skin and gut microbiota due to its chemical composition and physical presence, but the implications remain unclear. Rana dybowskii were exposed to five aqueous extracts of ashes (AEA) concentrations for 30 days to study survival, metal concentrations, and microbial diversity, analyzing the microbiota of the cutaneous and gut microbiota using Illumina sequencing. Dominant elements in ash: K > Ca > Mg > Na > Al > Fe. In AEA, K > Na > Ca > Mg > As > Cu. Increased AEA concentrations significantly reduced frog survival. Skin microbiota alpha diversity varied significantly among all treatment groups, but not gut microbiota. Skin microbiota differed significantly across treatments via Bray-Curtis and weighted UniFrac; gut microbiota was only affected by Bray-Curtis. Skin microbiota varied significantly with AEA levels in Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes, while the gut microbiota's dominant phyla, Firmicutes, Bacteroidetes, and Proteobacteria, remained consistent across all groups. Lastly, the functional prediction showed that the skin microbiota had big differences in how it worked and looked, which were linked to different health and environmental adaptation pathways. The gut microbiota, on the other hand, had smaller differences. In conclusion, AEA exposure affects R. dybowskii survival and skin microbiota diversity, indicating potential health and ecological impacts, with less effect on gut microbiota., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Symbiotic microbial communities are common in amphibians, and the composition of gut microbial communities varies with factors such as host phylogeny, life stage, ecology, and diet. However, little is known regarding how amphibians acquire their microbiota or how their growth, development, and environmental factors affect the diversity of their microbiotas. We sampled the gut microbiota during different developmental stages of brown frog Rana dybowskii, including tadpoles (T), frogs in metamorphosis (M), frogs just post-metamorphosis and after eating (F), juvenile frogs in summer (Js), adult frogs in summer (As), adult frogs in autumn (Aa), and hibernating frogs (Ah). We recorded data on the environmental (ambient temperature, fasting status, habitat, and season) and host (body mass and developmental period) factors. We investigated whether the gut microbiota diversity of R. dybowskii differs according to the host developmental stage via high-throughput Illumina sequencing and whether the gut microbiota diversity is affected by environmental and host factors. We found that alpha and beta diversity varied significantly during different developmental stages. The linear discriminant analysis effect size (LEfSe) analysis identified eight phyla exhibiting significant differences: Cyanobacteria (T group), Proteobacteria (M group), Fusobacteria (F group), Firmicutes (As group), Actinobacteria (Aa group), Verrucomicrobia (Aa group), Tenericutes (Aa group), and Bacteroidetes (Ah group). The Venn diagrams showed that 49 shared OTUs were present during all stages of development, whereas 10 OTUs were present in >90% of the samples. The environmental and host factors were significantly correlated with microbial community changes. Furthermore, the AIC-based model results suggested that development was the only variable that needed inclusion in the redundancy analysis (RDA) to explain the variance in taxa. These results have broad implications for our understanding of gut microbiota development and its associations with amphibian development and environmental factors., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)