Do microbes play a role in facilitating the range expansion of tropical fish into temperate systems?

A/Prof Adriana Verges1, Ines Richter1, Torsten Thomas1, Suhelen Egan1

1UNSW Sydney, Sydney, Australia

The climate-mediated range expansion of tropical, herbivorous fish into temperate regions has profound impacts on temperate reefs, through overgrazing of habitat-forming seaweeds. The mechanisms that control such novel plant-herbivore interactions between tropical consumers and temperate seaweeds are largely unknown, but recent studies show that microorganisms can strongly impact plant-herbivore interactions and can enable the use of novel plant hosts. In this study, we compared the microbial communities in the gastrointestinal tract of three range-shifting and four non-range-shifting species of closely related tropical surgeonfish as well as their diet source, the epilithic algae matrix (EAM). Further, we compared EAM and fish gut microbiome samples along a latitudinal gradient for the range-expanding convictfish Acanthurus triostegus. High-throughput sequencing of the 16S rRNA gene showed strong differentiation among tropical fish species, but these were not grouped by range-shifting status. Although the microbiome of the gastrointestinal tract of all fish species was distinct from their diet source, half or more of the microbial taxa found within the guts of surgeonfish were also found in local EAM samples. We found high dissimilarity in the gut microbial communities of tropical and temperate populations of A. triostegus, suggesting range-shifting fish acquire new microbial taxa to assist in the digestion of novel food sources when they move into higher latitude reefs.


Associate Professor Adriana Vergés is a marine ecologist working on the impacts of climate change on temperate reefs. She is based at UNSW Sydney and originally hails from Barcelona, where she obtained her PhD working on marine herbivory. She’s passionate about marine conservation and communicating science to the general public.

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