Like all animals, corals are inhabited by a microbial community – the coral microbiome. The coral microbiome is essential for coral health and can have a significant impact on coral bleaching tolerance. Research suggests that manipulating corals’ microbiome could further support coral heath and increase corals’ tolerance to environmental stress. The coral microbial community has large and diverse populations which have very short generation times and a large metabolic range compared with the coral host. Therefore, evolution can occur much more quickly within the coral microbiome than in coral. This method would aim to increase heat tolerance of the coral host (and potentially its subsequent progeny) through manipulating its microbiome.
Potentially, corals could be inoculated with microbes at early stages of life, or later as adults during periods of stress and recovery. While probiotics may be easily administered during the breeding process, it may be challenging to deliver them on a large scale in the field, as delivery methods are labour-intensive, and probiotics would need to be grown at significant quantities. It is not fully understood if the introduced probiotics would need to be continuously re-applied to be effective, and whether they could be passed down to offspring as well as to neighbouring corals. While coral probiotics could be a very promising tool to mitigate coral disease and enhance coral heat tolerance, potential side-effects on both the coral and other reef organisms would need to be examined.
Diagnosing, immunising against, and treating coral disease
Coral immunity to disease is thought to be diminished by warm seawater temperatures. Diagnosis, immunisation and disease treatment could limit the spread and effects of coral diseases and contribute to the recovery of bleached corals.
The ability to diagnose coral disease, and protect coral against it, is limited, as most causes of disease are yet to be fully understood. Strategies found to be successful in treating coral disease tend to be too labour-intensive for large-scale treatment.
Photo by Christopher Brunner
Phage (virus) therapy
Treating a bacterial disease with a virus – has been successful in aquaculture, and is a promising alternative to antibiotics.
Phage therapy has been successful in controlling disease-causing bacteria in coral; however, to be considered an option for large-scale application on the Reef, the potential risks would need to be studied, a robust coral disease diagnostic system established, and a new method to deliver these treatments would need to be developed.
Photo by Christian Miller