Standard Presentation (12 minutes) Australian Marine Sciences Association 2025 Conference

The importance of dispersal and herbivory in shaping the recruitment of Sargassum on an inshore reef in the central Great Barrier Reef (120230)

Martina Burgo 1 2 , Katharina Fabricius 2 , Andrew Hoey 1
  1. James Cook University, Townsville, QUEENSLAND, Australia
  2. Australian Institute of Marine Sicence, Townsville, Queensland

Settlement and early post-settlement mortality play a key role in determining the distribution of benthic organisms on temperate and tropical reefs. Macroalgae are common components of benthic communities on inshore coral reefs, yet little is known of the factors influencing their recruitment. In this study we quantified the relative importance of proximity to Sargassum beds (0, 15, 30, 45 m from the bed) and herbivory (caged vs uncaged) on the recruitment of macroalgae propagules to terracotta tiles. Recruitment was greatest to tiles within the Sargassum bed and decreased with distance from the bed, while exposure to herbivory had no/limited effect. Interestingly, we found that herbivory had a limited effect on Sargassum recruitment but was a strong control for settlement of other macroalgal genera. Our results suggest that the factors influencing the recruitment of Sargassum can vary at relatively small spatial scales.