Hanert, EmmanuelDeleersnijder, EricMeurice, RobinRobinMeurice2025-05-142025-05-142025-05-142019https://hdl.handle.net/2078.2/12546The Florida Reef Tract (FRT) is the third largest barrier reef in the world and lies at the southern end of Florida. Because of diseases, human activities and climate change, coral health and populations have declined in the last decades. In order to determine which coral reefs should be given the most attention to inhibit the destruction of the FRT, several studies focusing on coral connectivity were carried out. With this aim in mind, we studied the hydrodynamics of the FRT thanks to SLIM, a finite-element model solving shallow-water equations on an unstructured grid. We also used a Lagrangian particle tracker to follow coral larvae of two species: Montastrea Cavernosa (MC) and Acropora Cervicornis (AC). This tracker then provided us with a connectivity matrix, a square matrix of which each element gives the number of larvae that were seeded by a reef i and recruited by a reef j. We also used graph theory tools to treat this matrix and to identify connectivity properties of the FRT. In this study, we continued the work of Frys (2017) and Béchet and Verstraeten (2018) and investigated the impact that a hurricane could have on connectivity in the FRT. Florida is indeed subjected to increasingly more frequent and intense hurricanes. If the damage sustained by the corals are rather well documented, the changes in connectivity and the perspectives for coral development are not. We can indeed imagine that a hurricane is sufficiently strong to modify the larval dispersal in such a way that new connections between reefs are created. On the contrary, a hurricane might also cut off vital connections between reefs and have dramatic consequences on the coral network. To evaluate the impact of hurricanes, we focused on hurricane Irma, which made landfall on the FRT on 10 September 2017. It appeared that MC spawning season started on the same day and ended on 12 September. Since Irma had vanished from the area on 12 September, we could compare the larval dispersal and the resulting connectivity patterns between the larvae seeded on 10 and 12 September. Furthermore, we compared the total MC's connectivity with the connectivity of AC, which spawned a month before MC. AC's larval dispersal was thus barely impacted by Irma. The comparison between the connectivity properties of these two species showed that a hurricane similar to Irma would mainly affect the westernmost reefs of the FRT. These reefs indeed become greater suppliers of the network, but do no longer recruit many larvae. For that reason, protective measures affecting these reefs could be useful to face hurricanes comparable to Irma. Apart from these reefs, the scattered islands of the Florida Keys look sufficiently dense to hold back larvae from being sent away by the hurricane. The majority of the reefs thereby shows similar properties with and without hurricane conditions. Moreover, it appears that if a hurricane crosses the FRT during the spawning season, it will most likely enhance the diversification of the network. The different reefs will indeed benefit from the new connections enabled by the hurricane and combine their usual connections with the new ones to constitute a large and diverse cluster of reefs.CoralConnectivityHurricaneIrmaCycloneLarval dispersalSLIMtext::thesis::master thesisthesis:19505