Under the right living arrangement, disease-resistant corals can help “rescue” corals that are more vulnerable to disease, according to a new study.

For the study in the journal Scientific Reports, researchers monitored a disease outbreak at a coral nursery in Little Cayman, Cayman Islands.

The finding shows that when people grow corals of the same genotype—or genetic makeup—together, those corals are more vulnerable to disease than corals that grow among a mixture of genotypes. The study further found that some vulnerable corals can be “rescued” by resistant genotypes.

“We saw that some corals were more resistant to disease just by being around other corals that were particularly resistant,” says lead author Anya Brown, an assistant professor at the University of California, Davis, Bodega Marine Laboratory in the evolution and ecology department. “Proximity to these resistant genotypes helped buffer the susceptible corals from the effects of the disease.”

The findings provide further evidence that genetic diversity can help reduce disease transmission among corals, while also showing that it’s important to consider how corals are arranged in nurseries and reef restoration projects to prevent the spread of disease.

After an outbreak of white band disease spread through its coral nursery in Little Cayman, the nonprofit Central Caribbean Marine Institute worked together with the study’s academic authors to monitor its population of endangered Caribbean staghorn coral, A. cervicornis.

Before the outbreak, the nursery had attached coral fragments to plastic PVC frames to propagate them. Some frames held coral from a single donor colony. Other frames hosted corals from multiple donor colonies representing a mixture of genotypes.

After tracking the presence of the disease across 650 coral fragments for more than five months, the researchers found that corals living on frames with a mixture of genotypes were substantially more resistant to white band disease, a devastating bacterial disease that nearly wiped out A. cervicornis in the 1980s.

Read the full article about coral health by Kat Kerlin at Futurity.