Meeting Abstract
Despite being capable of both sexual and asexual reprouction, the major-reef builders in the Florida Keys have low to non-existent sexual recruitment rates. It is unknown how populations of these key species are being maintained. Focusing on the Orbicella genus, we hypothesize that coral populations are being maintained by storm-driven asexual reproduction: when a coral fragment breaks from the parent colony and grows into the reef to become its own individual colony, provided that is survives. While studies have been done on Acropora spp., no studies to date have investigated (1) whether hurricanes can cause boulder species to fragment, and (2) if so, whether such fragments can survive. To address these questions, we individually mapped and collected tissue samples from every coral and coral fragment along three 10-m transects at both an inshore and an offshore reef site in the Lower Florida Keys six weeks after Hurricane Irma made landfall. To identify species and assess clonality, DNA was extracted from 432 samples and genotyped using reduced representation 2b-RAD sequencing. The transects were resurveyed and resampled six and twelve months after the storm. The storm did result in substantial coral fragmentation: we identified storm-generated fragments of 8 different species, of which two boulder species, Orbicella annularis and O. faveolata, were the dominant fragmented species. We were able to genetically assign many of these fragments to parental colonies. Preliminary results show that hurricanes can fragment boulder corals, and poor water quality post-Hurricane Irma did not result in immediate fragment mortality.
