DOI: 10.5061/dryad.f1vhhmh0z
title: Mesophotic corals in Hawaii maintain autotrophy to survive low-light conditions: Stable isotope dataset

description: In mesophotic coral ecosystems, reef-building corals and their
 photosynthetic symbionts can survive with less than 1% of surface
 irradiance. How depth-specialist corals rely upon autotrophically and
 heterotrophically-derived energy sources across the mesophotic zone
 remains unclear. We analyzed the stable carbon (δ13C) and nitrogen (δ15N)
 isotope values of a Leptoseris community from the ʻAuʻau
 Channel, Maui, Hawaiʻi (65-125 m) including four coral host species living
 symbiotically with three algal haplotypes. We characterized the isotope
 values of hosts and symbionts across species and depth to compare trophic
 strategies. Symbiont δ13C was consistently 0.5‰ higher than host δ13C at
 all depths. Mean colony host and symbiont δ15N differed by up to 3.7‰ at
 shallow depths and converged at deeper depths. These results suggest that
 both heterotrophy and autotrophy remained integral to colony survival
 across depth. The increasing similarity between host and symbiont δ15N at
 deeper depths suggests that nitrogen is more efficiently shared between
 mesophotic coral hosts and their algal symbionts to sustain autotrophy.
 Isotopic trends across depth did not generally vary by host species or
 algal haplotype, suggesting that photosynthesis remains essential to
 Leptoseris survival and growth despite low light availability in the
 mesophotic zone.
description: # Mesophotic corals in Hawaiʻi maintain autotrophy to survive low-light
 conditions: Stable Isotope Dataset
 The complete collection of
 files used by Backstrom *et al.* (2024) to organize and analyze all stable
 isotope data presented in this research article. ## Description of the
 data and file structure The data are organized into three separate files,
 accompanied by an R script for processing/analyzing all biplot data: 1. A
 Microsoft Excel document (titled "ProcB Manuscript Data CHB
 1.15.24") provides a metadata sheet outlining the organized data on
 all subsequent sheets. These sheets were used to process/analyze all
 regression data via JMP Pro 14. Outliers as defined and listed in the
 sheet (and tabulated in Supplementary Table 1) were excluded for analyses
 pertaining to those data. 2. A .csv file titled
 "leptoseris.all.csv," reorganizing the stable isotope data for
 the whole sample set only by colony fraction (i.e., host vs. symbiont) to
 plot and run SIBER analyses. 3. Another .csv file titled
 "leptoseris.all.Hotelling.csv" reorganizing the same data
 presented in "leptoseris.all.csv" in a way that allows biplot
 stats via the Residual Permutation Procedure (RPP) as discussed in the
 text plus the Hostelling's T2 test, which was not reported but used
 to validate the RPP stats after checking for data normality. 4. The R
 script file, titled "Backstrom_ProcB_Biplot_Stats.R," that
 outlines the SIBER, RPP, and Hostelling's T2 stats based on the two
 .csv files of stable isotope data listed above. ## Description of data
 file columns and variables **1. Microsoft Excel Document: ProcB Manuscript
 Data CHB 1.15.24** The following column labels and corresponding variables
 are used in the Excel data sheets. Only newly used columns/variables are
 described for each subsequent sheet: **JMP_Paper_Regressions:** Sheet used
 for linear regressions of stable isotope values by host species, algal
 haplotype, and collection depth (m): 1. **ID Number**: The original number
 assigned to each unique coral colony collected by submersible for this
 study. 2. **Species**: each colony's host species (4 total): *L.
 scabra* (green), *L. tubulifera* (red), *Leptoseris* sp. 1 (yellow), and
 *L. hawaiiensis* (blue). Color coding for clarity and ease of distinction
 between species. 3. **Sample ID**: The sample ID assigned to each colony
 fraction for the analyses of this particular study, following the general
 format of "L_ID Number_Colony Fraction" (ex: "L27
 tissue", "L27 algae", etc.). Tissue signifies host
 fraction, whereas algae signifies symbiont fraction. 4. **N height (nA)**:
 the magnitude of the Elementar Isoprime100 Isotope Ratio Mass Spectrometer
 Nitrogen signature reading, in nanoAngstroms (nA). 5. **d15N**: The
 15-Nitrogen stable isotope signature derived from the N height (nA) and
 dry mass of the sample. 6. **N%**: The percent composition of Nitrogen
 found within each sample. Not incorporated in this study. 7. **C height
 (nA)**: the magnitude of the Elementar Isoprime100 Isotope Ratio Mass
 Spectrometer Carbon signature reading, in nanoAngstroms (nA). 8. **d13C**:
 The 13-Carbon stable isotope signature derived from the C height (nA) and
 dry mass of the sample. 9. **C%**: The percent composition of Carbon found
 within each sample. Not incorporated in this study. 10. **C:N Ratio**: the
 ratio of Carbon to Nitrogen for each sample, derived from dividing C% by
 N%. Not incorporated in this study. 11. **d15N**: host-symbiont: the
 isotopic difference in d15N values between host and symbiont samples, by
 colony. 12. **d13C**: host-symbiont: the isotopic difference in d13C
 values between host and symbiont samples, by colony. 13. **Depth Collected
 (m)**: the collection depth of each colony, in meters (m). 14. **5-m Depth
 Zone**: the collection depth of each colony, rounded to the nearest
 5-meter depth value. 15. **Collection Depth Bin (m)**: a copy of the 5-m
 Depth Zone column, used for all 5-m depth bin analyses. 16. **Coral %
 Cover**: an observational variable from previous studies of these
 *Leptoseris* colonies (e.g., Padilla-Gamiño et al. (2019); see reference
 list) providing environmental context of the percent coral cover found
 around the site of each colony's collection, relative to the rest of
 the benthos surrounding the colony. Not used in this study. 17.
 **Symbiodinium COI mtDNA: Coenosarc #1**: The COI algal haplotype of each
 coral colony, based on mitochondrial DNA of symbionts recovered from the
 coenosarc tissue in Pochon *et al.* (2015) (see reference list). 18.
 **Symb. COI mtDNA: Calyx**: The COI algal haplotype analyzed for a subset
 of colonies by Pochon *et al.* (2015) to confirm homogenous COI-type of
 algae across tissues of a single colony. N/A = not measured for that
 colony. 19. **Symb. COI mtDNA: Coenosarc #2**: Same as (18) above, but for
 a second sample of the coenosarc instead of the calyx material of each
 colony. 20. **Notes**: Additional notes on each sample. Duplicate averages
 were calculated on the "Duplicate_%diff" page. 21. **d13C,
 Residual**: Residual values of each d13C measurement, divided by colony
 fraction (tissue vs. algae) only, to detect and confirm outliers as
 identified by JMP histogram analyses. 22. **d13C, Cook's D
 Influence**: Cook's Distance values relative to the mean d13C values
 for tissue and algae samples, respectively. 23. **d15N, Residual**:
 Residual values of each d15N measurement, divided by colony fraction
 (tissue vs. algae) only, to detect and confirm outliers as identified by
 JMP histogram analyses. 24. **d15N, Cook's D Influence**: Cook's
 Distance values relative to the mean d15N values for tissue and algae
 samples, respectively. 25. **Outlier Issues: Exclude From:** Outlier
 assignment based on the residual, Cook's D, and histogram analyses.
 Outliers are labeled by variable (with commas separating outlier values in
 lists if multiple per sample). N/A signifies that the sample was not an
 outlier for any variables. **JMP_Paper_Iso_Diff:** Sheet used for linear
 regressions of differences in stable isotope values between host species
 and algal haplotype and collection depth (m). The only notable difference
 between this sheet and "JMP_Paper_Regressions" is that each
 colony has been condensed into a single row to list differences in
 isotopic values (d13C, d15N) between host and symbiont components (i.e.,
 tissue and algae) as single-row values. **JMP_Paper_Multi_Linear**: Sheet
 used for multivariate linear regression analyses in JMP, with each row
 representing all variable for both fractions (host and symbiont) for a
 single colony: 1. **N%, H**: the sample percent composition of Nitrogen,
 for the host fraction (H). 2. **N%, S**: the sample percent composition of
 Nitrogen, for the symbiont fraction (S). 3. **d15N, H**: the sample d15N
 stable isotope value, for the host fraction (H). 4. **d15N, S**: the
 sample d15N stable isotope value, for the symbiont fraction (S). 5. **Mean
 d15N**: the averaged value of both host and symbiont-fraction d15N
 signatures for the coral colony. 6. **C%, H**: the sample percent
 composition of Carbon, for the host fraction (H). 7. **C%, S**: the sample
 percent composition of Carbon, for the symbiont fraction (S). 8. **d13C,
 H**: the sample d13C stable isotope value, for the host fraction (H). 9.
 **d13C, S**: the sample d13C stable isotope value, for the symbiont
 fraction (S). 10. **Mean d13C**: the averaged value of both host and
 symbiont-fraction d13C signatures for the coral colony. 11. **C:N Ratio,
 H**: The Carbon-to-Nitrogen percent ratio for the host fraction (H). Not
 incorporated in this study. 12. **C:N Ratio, S**: The Carbon-to-Nitrogen
 percent ratio for the symbiont fraction (S). Not incorporated in this
 study. **Sample_Summary**: Sheet providing many of the parameters listed
 above but containing additional information about the sampling procedure.
 1. **Date**: The date that the samples were analyzed by Isotope Ratio Mass
 Spectrometer. 2. **Tray**: the 96-well plate tray number containing the
 specific sample. 3. **Genus**: the *Leptoseris* genus specifier
 (distinguished from other genera potentially run on the same tray). 4.
 **Sample Dry Weight (mg)**: the dry weight of the sample analyzed for
 stable isotopes, in milligrams (mg). **Duplicate_%diff**: Sheet providing
 percent difference calculations for all samples run in duplicate for
 quality control. 1. **Sample ID**: now includes rows for relative percent
 difference between both replicates listed above ("Rel. %
 Difference") and an average value provided as the final measurement
 for that duplicate sample ("Average [Sample ID] to report").
 **2. .csv File: leptoseris.all.csv** The following column labels and
 corresponding variables are used in this .csv file, with each row
 representing either a host or symbiont sample of a given colony: 1.
 **iso1**: the d13C value assigned to the specific sample (by row). 2.
 **iso2**: the d15N value assigned to the specific sample (by row). 3.
 **group**: the colony fraction ID (1 = host, 2 = symbiont). 4.
 **community**: the genus-level community ID for the specific sample ( = 1
 for all colonies, which belong to the same genus, *Leptoseris*). **3. .csv
 File: leptoseris.all.Hotelling.csv** The following column labels and
 corresponding variables are used in this .csv file, with each row
 representing either a host or symbiont sample of a given colony: 1.
 **gp**: the "group", i.e., the colony fraction ID (1 = host, 2 =
 symbiont). 2. **d13C**: the d13C value assigned to the specific sample (by
 row). 3. **d15N**: the d15N value assigned to the specific sample (by
 row). ## Code/Software R Script contains code derived from Conti-Jerpe et
 al. (2020) and Turner et al. (2010), as cited in the article. The R script
 is annotated to explain the format of all .csv files used in the code. All
 histogram and regression analyses were conducted in JMP Pro 14.