Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2024

Temporal self-organisation in tiger shark skin microbiomes despite fluctuations in diversity structure (104550)

Michael Doane 1 , Belinda Martin 1 , Lauren Meyer 1 , Charlie Huveneers 1 , Emma Kerr 1 , Ryan Hess 1 , Elizabeth Dinsdale 1
  1. Flinders University, Bedford Park, SA, Australia

Changes in the health of a host often coincide with alterations in the composition of its microbiome, where dominant microbial groups undergo shifts in both presence and abundance. This suggests a fundamental connection between microbiome diversity and the overall health of the host organism. Furthermore, the abundance of microbial members is influenced by various natural ecological factors, including spatial and temporal gradients in the environment. These complexities challenge the straightforward interpretation of microbiome diversity solely as a reflection of host health or ecological processes. Additionally, patterns of interaction among microbial communities have been linked to emergent functions, observed not only in bioreactors but also across disease states in humans. Previous work into host-microbiome patterns from whale shark skin suggests the skin microbiome remains stable across sharks from different global populations, despite variation in microbiome member abundances. In our study, we investigated the skin microbiome of 79 tiger sharks from Norfolk Island, Australia, over a span of three consecutive years. The overall aim of this project was to quantify the abundance and diversity of the skin microbiome over time and compare this to observed microbiome stability. Our analysis revealed that while alpha diversity at the family level remained consistent, significant variations in microbiome composition were observed across the three years of sampling. Interestingly, despite these compositional changes, the patterns of interaction among microbial species remained remarkably stable. The constructed networks exhibited similar numbers of clusters, consistent network modularity, and a balanced ratio of positive to negative interacting microbial groups. Furthermore, our findings highlighted the presence of microbial families occupying keystone positions within the networks despite their low abundance across samples. These findings align with documented observations of whale sharks across diverse geographical regions worldwide. Our hypothesis posits that the maintenance of stable network features is integral to fostering robust host-microbiome relationships, and any perturbations to these network dynamics may precipitate a disruption in this symbiotic association.