Deepwater corals are found on hard grounds of the continental shelf and slope of all ocean basins, where they enhance the abundance and biodiversity of invertebrates and fishes. Despite their essential role in deep-sea ecosystems, the knowledge of the factors that promote or impede connectivity among discrete coral communities remains elusive. Logistical challenges prevent a direct quantification of the essential factors affecting connectivity, such as timing of spawning, time spent in the water column, and settlement behavior, as well as the details of the physical environment and its variability. This study argues that an integrated framework including population genetic approaches and physical models of the ocean circulation with larval particle tracking capabilities can enhance our understanding. Genetic approaches allow determination of general time-integrated patterns of dispersal distance and direction in virtually any species, while transport models can refine understanding of the processes behind the observed dispersal patterns. Here, this integrated approach is applied towards investigating the connectivity of a deepwater coral, Callogorgia delta, along the upper continental slope of the northern Gulf of Mexico. The circulation in the basin is simulated by a regional ocean model at 1 km horizontal resolution, which is sufficiently detailed to allow for the generation and evolution of submesoscale eddies and vorticity filaments, and for a reliable representation of major bathymetric features. Building upon data from four sites spanning about 250 km of distance and 400 m of depth, it is concluded that depth differences on scales of tens to at most few hundreds of meters are sufficient to limit C. delta connectivity among sites. This result has important implications in the development of restoration and preservation strategies of deepwater corals in the Gulf of Mexico and calls for carefully accounting for the depth dimension in these efforts. Unit: m s-1.
