DOI: 10.5061/dryad.tv8v6k3
title: Data from: Trophic plasticity in a common reef-building coral: Insights from δ13C analysis of essential amino acids

description: 1. Reef-building corals are mixotrophic organisms that can obtain
 nutrition from endosymbiotic microalgae (autotrophy) and particle capture
 (heterotrophy). Heterotrophic nutrition is highly beneficial to many
 corals, particularly in times of stress. Yet the extent to which different
 coral species rely on heterotrophic nutrition remains largely unknown
 because it is challenging to quantify. 2. We developed a quantitative
 approach to investigate coral nutrition using carbon isotope (δ13C)
 analysis of six essential amino acids (AAESS) in a common Indo-Pacific
 coral (Pocillopora meandrina) from the fore reef habitat of Palmyra Atoll.
 We sampled particulate organic matter (POM) and zooplankton as the
 dominant heterotrophic food sources in addition to the coral host and
 endosymbionts. We also measured bulk tissue carbon (δ13C) and nitrogen
 (δ15N) isotope values of each sample type. 3. Patterns among δ13C values
 of individual AAESS provided complete separation between the autotrophic
 (endosymbionts) and heterotrophic nutritional sources. In contrast, bulk
 tissue δ13C and δ15N values were highly variable across the putative food
 sources and among the coral and endosymbiont fractions, preventing
 accurate estimates of coral nutrition on Palmyra. 4. We used linear
 discriminant analysis to quantify differences among patterns of AAESS δ13C
 values, or ‘fingerprints’, of the food resources available to corals. This
 allowed for the development of a quantitative continuum of coral nutrition
 that can identify the relative contribution of autotrophic and heterotopic
 nutrition to individual colonies. Our approach revealed exceptional
 variation in conspecific colonies at scales of meters to kilometers. On
 average, 41% of AAESS in P. meandrina on Palmyra are acquired via
 heterotrophy but some colonies appear capable of obtaining the majority of
 AAESS from one source or the other. 5. The use of AAESS δ13C
 fingerprinting analysis offers a significant improvement on the current
 methods for quantitatively assessing coral trophic ecology. We anticipate
 that this approach will facilitate studies of coral nutrition in the
 field, which are essential for comparing coral trophic ecology across taxa
 and multiple spatial scales. Such information will be critical for
 understanding the role of heterotrophic nutrition in coral resistance
 and/or resilience to ongoing environmental change.
description: READMEInformation about data
 files and variable namesR code for
 analysesThis script will open
 all data files and reproduce the analyses and main text figures for the
 manuscript.Fox et al.
 FE_code.RRaw Amino Acid d13C data
 from Palmyra AtollThis file contains all
 amino acid d13C measurements made on P. meandrina host and endosymbiont
 tissue and heterotrophic resources (POM and zooplankton) from Palmyra
 Atoll.Palmyra_AAd13C.csvBulk d13C and d15N dataThis file contains all bulk tissue d13C and d15N values to create the biplot in figure 2bBulk_13C_15N_Palmyra.csvLDA and Dd13C values for correlationThis file contains the data required to reproduce figure 4CLDA_Dd13C_corr_sites.csvConfidence interval estimatesThis file contains the data required to reproduce figure 2Cmean_CI_boostrap_for_plotting.csv