Mesophotic reef wall in the Egyptian Red Sea
Mesophotic Coral Ecosystems (MCEs) are coral reef communities that lie in the lower reaches of the sunlit surface waters. Despite their depth (30–150m, 100–500ft), corals in these habitats still retain their photosynthetic symbionts (Symbiodiniaceae spp.), and are thus still dependent on sunlight to survive.
Due to their depth and remoteness, MCEs are largely unexplored (Richard Pyle of the Bishop Museum has said that we know more about the deepest parts of the ocean than we do about the mesophotic zone). For that reason, we know very little about the ecology and community dynamics of these reefs. MCEs make up a major portion of the available reef habitat in the tropics and as such, their study and understanding is vital to our ability to properly conserve and manage coral reefs in the future.
My interest in deep reefs is severalfold.
First, I am interested in patterns of biodiversity along the depth gradient. Are there species that are found exclusively shallow and/or exclusively deep? If so, is there a depth where communities change from being dominated by shallow specialists to deep specialists? Does this depth vary among different taxa or is it more universal? What factors drive these changes?
Second, I am interested in the potential for biodiversity discovery on mesophotic reefs. Due to the unexplored nature of these habitats, there have been many new deep reef species described in recent years. What other previously-unknown species wait to be found?
Finally, I’m interested in whether deep species have different population characteristics than shallow specialists or depth generalists? Do they have different life history characteristics, spawning behaviors, dispersal patterns? Where do their larvae go? Are deep populations/species older and/or more stable than shallow ones?
Relevant Publications
Hoban, M.L., Hurley, K.K.C., Reardon, K. et al. Cryptobenthic crab assemblages are more distinct across a 90 m depth gradient than 2500 km of shallow marine habitat in the Hawaiian archipelago. Sci Rep 15, 27419 (2025). https://doi.org/10.1038/s41598-025-10232-6
Hoban, M. L., Bunce, M., & Bowen, B. W. (2023). Plumbing the depths with environmental DNA (eDNA): Metabarcoding reveals biodiversity zonation at 45–60 m on mesophotic coral reefs. Molecular Ecology, 32, 5590–5608. https://doi.org/10.1111/mec.17140
Copus, Joshua M., Cameron A. J. Walsh, Mykle L. Hoban, Anne M. Lee, Richard L. Pyle, Randall K. Kosaki, Robert J. Toonen, and Brian W. Bowen. 2022. “Phylogeography of Mesophotic Coral Ecosystems: Squirrelfish and Soldierfish (Holocentriformes: Holocentridae)” Diversity 14, no. 8: 691. https://doi.org/10.3390/d14080691