Data from: Geographic differences in vertical connectivity in the Caribbean coral Montastraea cavernosa despite high levels of horizontal connectivity at shallow depths

The Deep Reef Refugia Hypothesis proposes that deep reefs can act as local
recruitment sources for shallow reefs following disturbance. To test this
hypothesis, nine polymorphic DNA microsatellite loci were developed and
used to assess vertical connectivity in 583 coral colonies of the
Caribbean depth-generalist coral Montastraea cavernosa. Samples were
collected from three depth zones (≤10 m, 15-20 m and ≥25 m) at sites in
Florida Upper Keys, Lower Keys and Dry Tortugas), Bermuda, and the U.S.
Virgin Islands. Migration rates were estimated to determine the
probability of coral larval migration from shallow to deep and from deep
to shallow. Finally, algal symbiont (Symbiodinium spp.) diversity and
distribution was assessed in a subset of corals to test whether symbiont
depth zonation might indicate limited vertical connectivity. Overall,
analyses revealed significant genetic differentiation by depth in Florida,
but not in Bermuda or the U.S. Virgin Islands, despite high levels of
horizontal connectivity between these geographic locations at shallow
depths. Within Florida, greater vertical connectivity was observed in the
Dry Tortugas compared to the Lower or Upper Keys. However, at all sites,
and regardless of the extent of vertical connectivity, migration occurred
asymmetrically, with greater likelihood of migration from shallow to
intermediate/deep habitats. Finally, most colonies hosted a single
Symbiodinium type (C3), ruling out symbiont depth zonation of the dominant
symbiont type as a structuring factor. Together, these findings suggest
that the potential for shallow reefs to recover from deep-water refugia in
M. cavernosa is location-specific; varying among and within geographic
locations likely as a consequence of local hydrology.