Data from: High abundances of crustose coralline algae inside cryptic coral habitats linked to coral reef functioning

Cryptic habitats on coral reefs consist of crevices, tunnels, and holes
that are estimated to comprise 30-75% of the total reef surface area.
These large habitats are vastly understudied because they are often
difficult to access. Crustose coralline algae (CCA) are thought to perform
important ecological functions, including reef accretion and coral
recruitment, both inside cryptic habitats and on the exposed (top) reef.
Using GoPro cameras, we surveyed 250 coral crevices from 14 reefs on West
Maui, Hawai‘i. We documented CCA abundance and distribution, identified
abiotic and biotic factors that may regulate CCA abundance, and compared
relative CCA cover between crevices and the well-studied top-reef. We
found that crevices had 3.1 times more CCA cover on average than the
top-reef and that CCA cover was highest on the ceilings and entrances of
crevices that had low sediment and macroalgal cover. These findings
suggest that crevice openings and ceilings are particularly important for
reef building and stabilization of reefs, because of CCA’s known
contribution to calcium accretion. Thus, these findings help to establish
functional links between coral reef structural complexity, cryptic
habitats, and reef resilience, and highlight the importance of studying
cryptic habitats to inform approaches to coral reef conservation.