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

Dataset DOI: [10.5061/dryad.tx95x6b8p](10.5061/dryad.tx95x6b8p)

## Description of the data and file structure

**README - 5 August 2025**

**Anna Rothstein, Orion S. McCarthy, Sophie Luu, Emily L. A. Kelly, Philip Heller, Stuart A. Sandin, Jennifer E. Smith, Maya S. deVries. *Royal Society Open Science*. “High abundances of crustose coralline algae inside cryptic coral habitats linked to coral reef functioning.”**

There are four data files associated with this manuscript. They are listed here and described in detail below:

1. **“crevice_data_Rothstein_etal.csv”**
2. **“crevice_light_data_Rothstein_etal.csv”**
3. “**crevice_topreef_data_Rothstein_etal.csv**”
4. **“crevice_benthic_data_Rothstein_etal.csv”**

**1.  “crevice_data_Rothstein_etal.csv”**

This file contains the data for the analyses on all 250 coral crevices documented in this study and was used to analyz...,