Staghorn corals threatened by an emerging disease have been found to have some natural resistance, explaining why not all individuals die when the disease strikes.
Six percent of Acropora cervicornis staghorn coral genotypes show natural resistance to White Band Disease (WBD), with three out of 49 specimens being able to fend off the infection.
Steven Vollmer and David Kline of the Smithsonian Tropical Research Institute, who reported the study in the journal PLoS One, said that the results are the first to show disease resistance in scleractinian corals, demonstrating an innate ability to resist WBD infection.
White Band DiseaseWBD infections have caused unprecedented mortalities in two dominant shallow-water staghorn corals, A. cervicornis and A. palmata, but little is known about the resistance of corals to disease.
"This natural resistance to WBD in threatened staghorn corals provides the first evidence for host disease resistance in reef-building corals, and may explain why pockets of staghorn corals have survived the Caribbean-wide epidemic of WBD over the past thirty years", wrote the authors.
"It is possible that differences in the numbers of naturally resistant genotypes between reefs may explain for why some staghorn coral populations have fared better than others over the course of the WBD epidemic.
"Ultimately, however, the broad-scale recovery of staghorn coral populations across the greater Caribbean will have to be achieved by the successful dispersal and recruitment of staghorn coral larvae; preferably those carry genetic variation for WBD resistance."
Both A. cervicornis and A. palmata are now classified as critically endangered on the IUCN Red List.
Vollmer SV and DI Kline (2008) - Natural disease resistance in threatened staghorn corals. PLoS ONE. 2008; 3(11): e3718. doi: 10.1371/journal.pone.0003718.