The widespread decline of shallow-water coral reefs has fueled interest in assessing whether mesophotic reefs can act as refugia replenishing deteriorated shallower reefs through larval exchange. Here we explore the morphological and molecular basis facilitating survival of planulae and adults of the coral Porites astreoides (Lamarck, 1816; Hexacorallia: Poritidae) along the vertical depth gradient in Bermuda. We found differences in microskeletal features such as bigger calyxes and coarser surface of the skeletal spines in shallow corals. Yet, tomographic reconstructions reveal an analogous mineral distribution between shallow and mesophotic adults, pointing to similar skeleton growth dynamics. Our study reveals patterns of host genetic connectivity and minimal symbiont depth-zonation across a broader depth range than previously known for this species in Bermuda. Transcriptional variations across life stages showed different regulation of metabolism and stress response functions, unraveling molecular responses to environmental conditions at different depths. Overall, these findings increase our understanding of coral acclimatory capability across broad vertical gradients, ultimately allowing better evaluation of the refugia potential of mesophotic reefs.

Depth range
10- 45 m

Mesophotic “mentions”
95 x (total of 8863 words)

Classification
* Presents original data
* Focused on 'mesophotic' depth range
* Focused on 'mesophotic coral ecosystem'

Fields
Ecology
Molecular ecology
Physiology
Reproduction

Focusgroups
Scleractinia (Hard Corals)

Locations
Bermuda

Platforms
SCUBA (open-circuit or unspecified)