Report on the potential origin of the SCTLD in the Florida Reef Tract

For about six years, the Florida Reef Tract (FRT) has been experiencing an outbreak of the Stony Coral Tissue Loss Disease (SCTLD). Although the epicenter of the propagation of the disease has been identified off the coast of Miami-Dade County in 2014, the origin and identity of the agent responsible for the initiation of the epidemic remain unknown. A potential scenario is that this agent was transported to the first-affected coral colonies within material driven by currents. The goal of this preliminary study is therefore to identify the potential sources of such material. Backward and forward particle tracking from May to September 2014 suggested that fine matters suspended in the water column generated by phase III of the expansion of Port of Miami (November 2013 -March 2017) might have been transported south, to the first-identified diseased colonies. However, sediment modeling showed no sediment transport south to the dredged channel during our simulated period. An extension of the simulated period is therefore required to determine whether hydrodynamics allowed sediments to reach the first-affected colonies prior to May 2014. Besides, the modeled impact of sediments on the reefs located north to the dredged channel suggest that the SCTLD outbreak might have been initiated north to the reefs where it was first observed by Precht et al. (2016). Further propagation studies would assess the feasibility of disease transmission from the north to the south of the dredged channel.