Bacteria Increases Coral Disease Risk???

 By: Melissa Villareal 

The figure shows an increased population of Ca. Aquarickettsia (green) in susceptible coral while a decreased population in bleached coral. Conversely, resistant coral had higher bacteria diversity. Figure taken from Klinges et al. 2021. 

Reef-building coral such as the Acropora cervicornis, are important in marine ecosystems because they directly influence the biodiversity of marine species. Coral have beneficial microbes that keep them healthy and they provide defenses against harmful pathogens. A study by Klinges and colleagues (2020) showed that the parasitic bacteria, Candidatus Aquarickettsia rohweri’, steals nutrients from coral and plays a role in the susceptibility of coral to bleaching-disease. This pathogen is associated with decreased growth, loss of tissue and increased mortality in coral. A high abundance of this pathogen serves as a biomarker in detecting which coral has high susceptibility for disease. When a coral is under thermal stress, it can result in coral bleaching-disease. Once the coral bleaches, the Ca. Aquarickettsia bacteria population decreases because it can no longer feed on the coral.

Overall, coral bleaching is a serious disease that affects the ecosystem of marine life, and the loss of coral will have a devastating effect. Many coral species are listed as endangered, and research is important in their conservation and repopulating these reefs. Unfortunately, this disease is very complex, so analyzing every contributing factor is crucial to their survival. This research on this biomarker for coral disease allows for better conservation methods.

Original Article:

Klinges, G., Maher, R.L., Vega Thurber, R.L.and Muller, E.M. (2020) Parasitic ‘ Candidatus Aquarickettsia rohweri’ is a marker of disease susceptibility in Acropora cervicornis but is lost during thermal stress. Environ Microbiol 22: 5341–5355.