Abstract
Skin microbiota is necessary for optimal health and protection from pathogenic microorganisms.1,2 Northern elephant seal skin disease (NESSD) is a potentially fatal, ulcerative, alopecic dermatitis in young free-ranging, northern elephant seals (Mirounga angustirostris; NES).3-7 The etiology is unknown but skin dysbiosis may be a factor.3,4,5 The aim of this study was to characterize the microbiome of normal and alopecic skin from healthy and stranded NES.
Stranded NES (n=17) admitted to The Marine Mammal Center (TMMC) and five free-ranging NES weanlings were sampled between December 2021 and May 2022. All had normal skin and hair except for five free-ranging and one stranded animal that had at least one area of alopecia. Skin swabs were collected from the top of head, dorsum, under eye, pelvic flipper, and, if present, an area of alopecia from each animal. At least one null air sample was taken at each geographic location. Purified DNA from a total of 105 swabs was analyzed using Illumina 16S sequencing.
The microbiome of non-alopecic NES body sites was mainly comprised of Psychrobacter sp.
Some alopecic sites contained sequences from Balneicella sp. and Dietzia psychralcaliphila. A Shannon diversity index (SDI) and a beta diversity principal coordinate analysis between body sites of non-alopecic NES found no significant difference (p>0.1), indicating that the microbial diversity is similar for all sites. The SDI of non-alopecic animals was significantly different from that of animals with alopecia (p<0.05); however, the difference between the normal sites and alopecic sites on the affected seals was not statistically significant. Ultimately, characterizing the normal cutaneous microbiome of NES may provide insight into the microbial role in host health and serve as a reference for studying skin disease in this species.
Acknowledgments
The authors wish to thank The Hervey Family Non-Endowment Fund at The San Diego Foundation and The Marine Mammal Center clinical and pathology team, staff, volunteers, and donors who made this research possible. Field research was conducted under MMPA permit #21018. Rescue and rehabilitation activities at The Marine Mammal Center were conducted under NOAA permit #18786-04.
*Presenting author
+Student presenter
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