Variation in the sensitivity of intestine and skin of Bufo gargarizans and Rana chensinensis tadpoles in relation to zinc exposure.

Zinc (Zn) contaminants in the aquatic environment have an intricate impact on amphibians. Amphibian gut and skin microbiota are participated in regulating their normal physiological functions. Here, we investigated the effects of Zn on the gut and skin tissues and microbiota of Bufo gargarizans and Rana chensinensis tadpoles using histological methods and 16S rRNA sequencing technology. Our results showed a decrease in the height of enterocytes and skin epithelial cells after Zn treatment. Furthermore, Zn exposure elicited alterations in the composition and structure of the gut and skin microbiota at the phylum and genus levels in Bufo gargarizans and Rana chensinensis tadpoles. The feature predictions revealed an elevation in the abundance of potentially pathogenic bacteria and stress-tolerant bacteria in the gut and skin of both tadpoles after zinc exposure. We also speculated that microbiota from various species and organs exhibit varying degrees of sensitivity to zinc based on the functional predictions results. In the context of increasing environmental pollution and the global amphibians decline, our research enriches the current understanding of effects of zinc on amphibian microbiota and provides new framework for artificial breeding and amphibian conservation.