Antifouling treatments for coral settlement devices 

Reef restoration using sexually produced corals involves culturing millions of millimetre-sized coral larvae and settling them on devices as polyps. 

These devices are then deployed onto a reef where recruits grow into coral colonies.  

The survival of coral recruits during their most vulnerable first months needs to be maximised to achieve feasible and affordable restoration at a large scale.   

Currently, the survival of coral recruits is typically less than 10 percent, represents one of the greatest barriers to scaling up reef restoration.  

One of the most common causes of mortality is competition and overgrowth of coral recruits by algae on deployment devices.  

Chemical surface coatings can reduce algal fouling and promote coral survival.  

There are several low-toxicity antifoulants designed to protect boats and aquaculture operations from fouling which could be applied to coral deployment devices to reduce competition by algae and maximise coral recruit growth and survival both before and after reef deployment.   

In the National Sea Simulator during the 2020 spawning, coral larvae will be settled on deployment devices treated with a range of low-toxicity antifoulants such as silicone barrier release coatings.  

The performance of these coatings to reduce algal competition and improve coral recruit survival will be assessed.  

The most promising treatments will then be tested in reef deployments in subsequent years.  

Coupled with innovative deployment devices, the successful application of antifouling treatments to improve coral recruit survival over their first months could dramatically reduce the costs associated with restoration using sexually produced corals.