The role of Typhoon Maysak on the dispersal of Montipora sp. in Ulithi, Federated States of Micronesia

The Atoll of Ulithi, Yap State, Federated States of Micronesia, has experienced an increase in abundance of a "weedy" coral, Montipora sp., in the past few decades, with significant detrimental effects on the local coral... [ view full abstract ]

The Atoll of Ulithi, Yap State, Federated States of Micronesia, has experienced an increase in abundance of a "weedy" coral, Montipora sp., in the past few decades, with significant detrimental effects on the local coral reefs. It has been proposed that this sudden increase followed a Typhoon that occurred in the 1960s. In April 2015, Typhoon Maysak directly hit Ulithi, causing severe damage on land and on the shallow reefs. A few weeks later, and again a full year after the Typhoon, fragments and colonies of Montipora were collected.  RAD genomic sequencing was performed to evaluate the potential role of Typhoon Maysak on the spread of Montipora. Relatedness analysis allowed to unambiguously identify colonies and determine which individuals were genetically identical. Colonies were found to be surprisingly diverse genetically, for a fast colonizing species. We were also able to estimate dispersal, and quantify the role of the Typhoon in spreading Montipora over the seafloor. Fragments were spread by tens of meters, and were found to survive a full year after the Typhoon had passed, indicating that fragments lived long enough to reattach and start new colonies. With the predicted increase in frequency and intensity of Typhoon events in the near future due to global climate change, this study shows that subtidal ecological effects of reoccurring Typhoons may have a significant impact on the overall health of reefs.