GEOGRAPHIC INFLUENCES ON THE SKIN MICROBIOME OF HUMPBACK WHALES

Abstract

Assessing the health state of wild marine mammals and their populations is challenging, and there is a growing need to develop reliable proxies for health determination. Climate change and other anthropogenic factors are influencing disease prevalence and virulence in the marine environment and there is a need to improve tools and techniques for monitoring the health status of wild marine mammals that are listed as threatened or endangered. The skin is the largest mammalian organ and serves as the first line of defense between the host and their external environment. Most research has focused on human health and has found that the skin microbiome can serve as a protective mechanism by adding to the skin’s defense against colonization of potential pathogenic bacteria. The skin is relatively well-sampled in marine mammals and may serve as a useful proxy for health status, as demonstrated in humans. However, before skin microbiomes become useful health diagnostic tools for marine mammals, more information is needed about the factors influencing variability within the skin microbial community. I analyzed the skin microbiome of 72 apparently healthy humpback whales primarily from Antarctica, as well as Alaska, Hawaii, American Samoa, and the Gulf of Maine. Phylogenetic and statistical analyses revealed two dominant families of bacteria (Moraxellaceae and Flavobacteriaceae) found on each individual whale. However, there were significant differences in the skin microbiomes amongst whales from different geographic areas, both globally as well as amongst regions within Antarctica. These findings provide support that there is a species-specific microbiome on humpback skin that varies according to geographic factors. This initial characterization of the healthy humpback skin microbiome in Antarctica is helpful for future health diagnostic efforts aimed especially at heath-compromised animals. This research ultimately aims to be the building blocks for exploring how the skin microbiome can be used as a diagnostic tool for monitoring marine mammal health.