Data from: High abundances of crustose coralline algae inside cryptic coral habitats linked to coral reef functioning
Data files
Aug 05, 2025 version files 38.26 KB
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crevice_benthic_data_Rothstein_etal.csv
6.42 KB
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crevice_data_Rothstein_etal.csv
20.86 KB
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crevice_light_data_Rothstein_etal.csv
907 B
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crevice_topreef_data_Rothstein_etal.csv
1.96 KB
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README.md
8.12 KB
Abstract
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.
Dataset DOI: 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:
- “crevice_data_Rothstein_etal.csv”
- “crevice_light_data_Rothstein_etal.csv”
- “crevice_topreef_data_Rothstein_etal.csv”
- “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 analyze correlations between crustose coralline algae (CCA) abundance and crevice depth, microhabitat type, and sedimentation. For detailed descriptions of how the data were collected and analyzed, refer to the Materials and Methods section in the associated manuscript. Each column title in the spreadsheet is described below.
Crevice_ID: The unique identifier given to each crevice filmed in the study. Each identifier has the site abbreviation and a letter denoting the specific crevice.
Site_name: The site names for each coral crevice. The abbreviations are listed from North to South in West Maui below (see Fig. 1 in associated manuscript for a map of the study sites):
- Honokowai 1 [HONO1]
- Kahekili 5 [KAH5]
- Kahekili 2 [KAH2]
- Kahekili 1 [KAH1]
- Wahikuli [WAH]
- Olowalu 1 [OLO1]
- Olowalu 2 [OLO2]
- Olowalu 3 [OLO3]
- Ukumehame 1 [UKU1]
- Keawakapu [KEA]
- Molokini Shallow [MOLOS]
- Molokini Deep [MOLOD]
- South La Perouse Bay [SLPB]
Depth.m: The depth of each site (units: m).
Crevice.cm: The crevice depth measured using the telescopic extender (selfie stick) when camera was inserted into the crevice (units: cm).
Microhabitat: Microhabitat of the given screenshot analyzed within the specific crevice. The two microhabitats documented were:
- WALL: The camera was oriented towards the back wall of the crevice
- CEILING: The camera was oriented towards the ceiling of the crevice
SED.TURF: The relative abundance of sediment and sediment-laden turf as a measure of sedimentation inside crevices (units: %).
CCA: Relative CCA abundance inside crevices (units: %).
ratiocca: Relative CCA abundance as a ratio
ratiosedturf: relative abundance of sediment and sediment-laden turf as a ratio
2. “crevice_light_data_Rothstein_etal.csv”
This file contains the light data collected at one site (KAH 2) and was used to analyzed correlations between CCA abundance and light availability, crevice depth, microhabitat type, and sedimentation. For detailed descriptions of how the data were collected and analyzed, refer to the Materials and Methods section in the associated manuscript. Each column title in the spreadsheet is described below.
Crevice_ID: The unique identifier given to each crevice filmed in the study.
Light.reading.lumens: Light readings for each crevice. Data were taken from the approximately one minute that the probe was in the crevice. These data were then used to calculate average light readings for each crevice (units: lumens).
Microhabitat: Microhabitat of the given screenshot analyzed within the specific crevice. The two microhabitats documented were:
- WALL: The camera was oriented towards the back wall of the crevice
- CEILING: The camera was oriented towards the ceiling of the crevice
Crevice.depth.cm: The crevice depth measured using the telescopic extender (selfie stick) when camera was inserted into the crevice (units: cm).
CCA: Relative CCA abundance inside crevices (units: %).
SED.TURF: The relative abundance of sediment and sediment-laden turf as a measure of sedimentation inside crevices (units: %).
ratiocca: Relative CCA abundance as a ratio
ratiosedturf: relative abundance of sediment and sediment-laden turf as a ratio
3. “crevice_topreef_data_Rothstein_etal.csv”
This file contains crevice and top-reef data collected from 8 sites for which there were top-reef data available. The data were used to analyze differences in CCA abundance and sedimentation between the top reef and crevice ceilings and walls. The data were also used to explore potential differences in CCA abundance between different coral morphotypes. For detailed descriptions of how the data were collected and analyzed, refer to the Materials and Methods section in the associated manuscript. Each column title in the spreadsheet is described below.
Habitat.type: Habitat types documented at a given site. The two habitat types documented were:
- crevice: coral crevice
- top-reef: the exposed top of the reef
Microhabitat: Microhabitats documented at a given site. The three habitat types documented were:
- ceiling: The camera was oriented towards the ceiling of the crevice
- wall: The camera was oriented towards the back wall of the crevice
- top-reef: The whole top of the reef within the 10x10m plot as documented from large-area imagery
Site_name: The site names for each coral crevice. See above for definitions of abbreviations.
coral_type: The dominating coral morphotype for at each site. The three morphotypes documented were:
- b: branching coral
- m: massive coral
- p: plating coral
CCA: Relative CCA abundance inside crevices (units: %).
SED.TURF: The relative abundance of sediment and sediment-laden turf as a measure of sedimentation inside crevices (units: %).
ccaturf: The ratio of CCA:turf algae.
ratiocca: Relative CCA abundance as a ratio
ratioturf: relative abundance of sediment and sediment-laden turf as a ratio
4. crevice_benthic_data_Rothstein_etal.csv
This file contains crevice and top-reef benthic data collected from 8 sites for which there was top-reef data available. The data were used to analyze differences in the relative abundances of benthic organisms using a Non-metric MultiDimensional Scaling (NMDS) analysis. For detailed descriptions of how the data were collected and analyzed, refer to the Materials and Methods section in the associated manuscript. Each column title in the spreadsheet is described below.
Habitat.type: Habitat types documented at a given site. The two habitat types documented were:
- crevice: coral crevice
- top-reef: the exposed top of the reef
Microhabitat: Microhabitats documented at a given site. The three habitat types documented were:
- ceiling: The camera was oriented towards the ceiling of the crevice
- wall: The camera was oriented towards the back wall of the crevice
- top-reef: The whole top of the reef within the 10x10m plot as documented from large-area imagery
Site_name: The site names for each coral crevice. See above for definitions of abbreviations.
Category: The category names for organisms encountered in the crevices and on the top-reef.
n: The number of individuals per category encountered within each documented crevice.
Code/software
Data were analyzed using R (v. 4.4.1, 2024). We transformed the percent data into proportions and constructed a beta regression model (package: betareg) to examine the relationship between relative CCA abundance and the microhabitats inside the reef (crevice ceilings vs walls), crevice depth, and the abundance of sediment and sediment-laden turf across sites to account for differences between sites.
To describe sediment and turf algal dynamics inside the reef, we examined the relationship between the CA:turf algal ratio and microhabitat using a generalized linear model (as opposed to a beta regression model) because there were ratios that were greater than 1.
Finally, we used a Non-metric MultiDimensional Scaling (NMDS) analysis to visualize differences in CCA percent cover between the top-reef and crevice walls and ceilings.