Assessing inter-annual, inter-specific and hurricane-induced connectivity variability in Florida's Coral Reef and its impact on restoration site selection

Dobbelaere, Thomas [UCL] Hanert, Emmanuel [UCL] et al.

Coral reefs are declining under the combined effect of ocean warming and acidification, and intensifying hurricanes. These warmer conditions favor coral disease outbreaks in coral disease hotspots such as Florida by weakening corals and increasing the abundance and virulence of pathogens. Local actions are thus required to mitigate the effects of climate change and support coral recovery. The efficiency of such actions can be maximized using connectivity estimates computed by biophysical models simulating the life-traits and transport of coral larvae down to the reef scale. However, due to the important computational cost of such models, connectivity studies often consider a small number of coral species over a limited number of spawning events, therefore lacking inter-annual and inter-specific variability. Here, we used the multiscale ocean model SLIM to simulate the dispersal of larvae from 7 coral species in Florida’s Coral Reef over 10 consecutive years (2012-2022). Moreover, we coupled SLIM to a high-resolution wave model to study the impact of Hurricane Irma on the dispersal of coral larvae and stony coral loss disease (SCTLD) agents in 2017. Using this model, we identified reefs with consistently high restoration potential for all simulated years and species, and quantified the variability of the communities in the connectivity networks. Furthermore, we found species with highly correlated connectivities, therefore highlighting the potential for coupled restoration strategies. Finally, our results suggest that hurricanes have the potential to create new long-distance connections for larval exchanges but also to accelerate the propagation of coral diseases. This study provides unprecedented easy-to-access reef-scale connectivity datasets to inform the design of future marine conservation strategies, and gives them tools to handle the increased variability and accelerated rate of change within coral reef ecosystems caused by intensifying hurricanes.