How do grazing fishes contribute to the high mortality of young coral?

It’s estimated that, in many cases, over 90% of corals die within their first six months of life, with some of this mortality linked to the intense feeding habits of large herbivorous fishes. 

To optimise reef restoration efforts, we need to better understand the ecological, biological, and environmental drivers that influence these high rates of mortality, including the role of grazing fishes.  This will improve our ‘coral seeding’ restoration methods, which have the potential to speed the return of coral cover to reefs that are degraded or damaged, and don’t receive adequate larval supply to recover naturally. 

In this research project, the team collects wild corals from the Great Barrier Reef to spawn in the National Sea Simulator. In the lab, the researchers will settle and rear coral recruits on devices designed to deter or exclude grazing fishes. 

Early next year, in January and February, the team will place these coral juveniles back on their home reef at multiple sites.  Researchers will monitor the survival of the corals on each device over the following year. 

The project will help us understand how grazing pressure varies along a wave-energy gradient, and how this, in turn, influences the survival of young corals seeded onto the reef. 

Results of this research will guide and improve direct restoration initiatives utilizing coral seeding devices.

Feature image: Taylor Whitman