Abstract

Predicting the relative susceptibility of reef areas to storm damage is important to stakeholders. Damage susceptibility depends primarily on exposure to waves and the fragility of the resident corals. Coral fragility is primarily related to shape and size which are related to species. Calculations based on colony measurements implies a large difference, O(10-100:1) between the fragility of massive and branching species. Here we estimate the relative fragility of various species using detailed damage survey data from 150 sites in Puerto Rico (PR) and 67 sites in Florida following the passage of hurricanes Irma and Maria in September of 2017. In PR both a transect and a roving survey were conducted near most sites. The damage measured in the two surveys near the same sites were not well correlated, making them relatively independent. We estimate species fragility as the average fraction damaged across all surveys of each type where that species was reported. Contrary to the same site damage results, the relative fragility between species was highly correlated across the different survey types. The difference between the measured fragility of branching and massive species was much smaller O(4:1) than the geometric calculations imply and there were variations within the massive species which were consistent and were significant when used in a simple reef damage model.