Full details of the experimental design are in:
Grottoli AG, Warner ME, Levas SJ, Aschaffenburg MD, Schopef B, McGinley M, Baumann J, Matsui Y. 2014. Cumulative impact of annual coral bleaching can turn some coral species winners into losers. Global Change Biology. doi:10.1111/gcb.12658
A brief description of the analytical methods follows.
Calcification, endosymbiotic algae concentration, total energy reserves, and Symbiodinium identification. Calcification rates were calculated from the buoyant weight data (Jokiel et al., 1978) and standardized to surface area. Endosymbiont cell concentration (Warner et al., 2006), and total soluble lipid, soluble animal protein, and soluble animal carbohydrates (Levas et al., 2013, Rodrigues & Grottoli, 2007) were measured on all frozen fragments. Total energy reserves were calculated as the sum of total lipids, protein, and carbohydrates and reported in Joules (Gnaiger & Bitterlich, 1984) per gram ash free dry weight of coral tissue. Since polyp structure and the coral tissue thickness of each species are different, this normalization facilitates inter-species comparisons (Edmunds & Gates, 2002). Genetic characterizations of Symbiodinium were determined by amplification of the internal-transcribed spacer 2 region (ITS2), followed by denaturing gradient gel electrophoresis and cycle-sequencing (Warner et al., 2006). This method reliably identifies the dominant symbiont type in healthy and bleached corals (LaJeunesse et al., 2004, LaJeunesse et al., 2009, Warner et al., 2006) and provides qualitative identification of other background Symbiodinium, either within different clades (e.g., endosymbionts A3 vs B1) or at the intra-cladal scale (e.g., endosymbionts A3 and A13) within the same coral fragment. The dominant ITS2-types (intra-cladal designations) are listed for each coral species in the text, while for statistical analyses (described below), the dominant symbiont for each coral fragment treatment-1 was grouped by clade. Specific quantitative PCR for all clades confirmed the accuracy of scoring dominant bands by DGGE analysis (data not shown, McGinley, 2012).
Photosynthesis, respiration, and feeding. Maximal photosynthesis and respiration rates were measured via changes in dissolved oxygen on each individual coral fragment immediately following their respective thermal stress then standardized to ash free dry weight (Rodrigues & Grottoli, 2007). All fragments were placed back on the reef and then feeding rates of each coral fragment were determined using methods in Palardy et al. (2008). Photosynthesis and respiration were used to calculate the percent Contribution of Zooxanthellae (Symbiodinium spp.) to Animal Respiration (CZAR) (Muscatine et al., 1981), while respiration and feeding rates were used to calculate the percent Contribution of Heterotrophy to Animal Respiration CHAR (Grottoli et al., 2006, Palardy et al., 2008). The Contribution of the Total acquired fixed carbon relative to Animal Respiration (CTAR) was calculated as the sum of CZAR and CHAR.