Comparative analysis of the skin microbiota between two sea snakes, Hydrophis cyanocinctus and Hydrophis curtus, with versus without skin ulcer.

Skin diseases pose a significant threat to animals. We obtained 35 adult annulated sea snakes (Hydrophis cyanocinctus) and 30 adult Shaw's sea snakes (Hydrophis curtus) collected as fishing bycatch from the coastal waters of Sanya, Hainan, South China. Nearly 2/3 of these snakes had signs of skin ulcer and were therefore assigned as sick ones. Of these sea snakes, 21 (14 sick and 7 healthy) adults of each species were used to conduct this study. Specifically, we used high-throughput 16S rRNA and ITS gene sequencing technology to characterize the skin bacteria and fungi and identify the possible pathogens responsible for skin disease by comparing the skin microbiota between the two sea snakes with versus without skin ulcer. The bacterial alpha diversity indices were higher in H. curtus than in H. cyanocinctus, and were higher in healthy snakes than in sick ones. None of fungal alpha diversity indices differed between species and between sick and healthy snakes. Skin microbial communities differed between H. curtus and H. cyanocinctus and between sick and healthy snakes. Skin ulcer was caused by combined bacterial and fungal infection, with bacteria of the genus Arcobacter being the common pathogen in both species. Bacteria of the genera Maritalea, Pseudomonas and Paracoccus formed an important pathogen group in H. curtus, and so did bacteria of the genera Tenacibaculum, Maritalea and Vibrio in H. cyanocinctus. Fungi of the genus Aspergillus were the pathogen in H. cyanocinctus, and so were fungi of the genus Verticillium in H. curtus. Future work could usefully find more information on the pathogen of skin diseases and thereby optimize treatment protocols for these diseases in sea snakes. [ABSTRACT FROM AUTHOR]