Composition and structure of the skin microbiota of rorquals off the Eastern South Pacific.

Recent advances in high-throughput sequencing have enabled the large-scale interrogation of microbiota in the most diverse environments, including host-associated microbiota. This has led to the recognition that the skin microbiota of rorquals is specific and structurally different from that of the ocean. This study reveals the skin microbiome of 85 wild individuals along the Chilean coast belonging to Megaptera novaeangliae, Balaenoptera musculus and Balaenoptera physalus. Alpha diversity analysis revealed significant differences in richness and phylogenetic diversity, particularly among humpback whales from different locations and between blue and humpback whales. Beta diversity was partially explained by host and location but only accounting for up to 17% of microbiota variability (adjusted VPA). Overall, we found that microbiota composition was dominated by bacterial genera such as Cardiobacter, Moraxella, Tenacibaculum, Stenotrophomonas, Flavobacteria and Pseudomonas. We also found that no ASVs were associated with the three rorqual species. Up to four ASVs were specific of a location, indicating a great variability in the microbiota. To the best of our knowledge, this is the first report on the composition and structure of the skin microbiota of whales off the coast of Chile, providing a foundational dataset to understand the microbiota's role in rorquals.