Studies show that baby corals are prone to devastating reef diseases

Baby brain corals are being nurtured at the Coral Reef Futures lab at the Rosenstiel School, where they are healthy and eight months old. Credit: Liv Williamson, Ph.D.

According to a recent research headed by experts at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, baby corals are equally as susceptible as adults to a lethal disease that has been spreading over Florida’s reefs since 2014, according to the study. Baby corals are susceptible to stony coral tissue loss disease (SCTLD), according to the research. The illness manifests itself in the same severity and mortality as in adult coral colonies. This is the first research to demonstrate the effects of any coral illness on newborn corals, and it is the most comprehensive.

Inclusion of young corals in disease surveys on Florida reefs likely underestimated disease mortality, said main author Olivia (Liv) Williamson, a Ph.D. student in the UM Rosenstiel School’s Department of Marine Biology and Ecology, For example, attempting to understand how COVID-19 spreads across a community by just observing adults would be analogous to attempting to understand whether and how the illness affects children.

Researchers exposed young boulder brain coral (Colpophyllia natans) and grooved brain coral (Diploria labyrinthiformis) from four to eight months to water harbouring colonies with active SCTLD for four weeks. Both species developed lesions within 48 hours of being exposed to the irritant.

Approximately 60% of the boulder brain coral babies perished within two to eight days after acquiring lesions after being exposed to the first dose of radiation. In contrast, just one fatality occurred among the disease-exposed grooved brain coral babies over the same period, but 38 percent of the disease-exposed grooved brain coral newborns had active disease lesions during the same period.

They also discovered that larger babies, as well as babies that were grouped together, were considerably less likely to develop ill and die than smaller and lonely newborns.

According to Williamson, “there is a glimmer of optimism in the fact that size counts and that there is safety in numbers.” Given that some of them avoided being sick at all, this shows that certain corals may possess a degree of resilience to illness, or at the very least may be less sensitive to it than others.

In order to further test the coral kids’ tolerance, the researchers exposed them to a second time after 20 days. All of the coral babies perished after six days of the second exposure.

The findings of this study serve as an important warning to coral restoration practitioners about the risk of SCTLD in baby corals that they grow and outplant. However, the findings also suggest that this risk can be reduced by growing coral recruits larger and encouraging grouping before outplanting coral.

Juvenile corals are as sensitive to SCTLD as adult colonies, if not more so, indicating that the magnitude of coral mortality caused by SCTLD on reefs has been underestimated due to a lack of information on coral recruitment.

It is the intention of the study team to perform more laboratory studies to discover sources of resistance, with the ultimate objective of assisting in the breeding and raising of young corals that will not succumb to this illness.

Stony coral tissue loss disease has spread throughout Florida’s coral reefs and the wider Caribbean since it was first discovered in the waters off Miami in 2014. The disease has now affected over 20 coral species and killed millions of coral colonies since its discovery in the waters off Miami in 2014. The lethal illness, which produces white lesions and fast tissue loss in reef-building corals, has not yet been determined to be the origin of the sickness.

In the journal Frontiers in Marine Science, the research team includes Olivia Williamson, Carly Dennison, and Andrew Baker from the University of Miami Rosenstiel School of Medicine, as well as Keri O’Neil from the Florida Aquarium.

Further information: Olivia M. Williamson et al, Susceptibility of Caribbean Brain Coral Recruits to Stony Coral Tissue Loss Disease (SCTLD), Frontiers in Marine Science (2022). DOI: 10.3389/fmars.2022.821165

Journal information: Frontiers in Marine Science

Source: University of Miami