||Muscatine, L. Falkowski, P. G., Dubinsky, Z., Cook, P. A. & McCloskey, L. R. (1989). The effect of external nutrient resources on the population dynamics of zooxanthellae in a reef coral. Proceedings of Royal Society of London B 236(1284), 311–324 DOI: 10.1098/rspb.1989.0025 AND Grottoli, A. G. & Wellington, G. M. (1999). Effect of light and zooplankton on delta C-13 values in the eastern Pacific corals Pavona clavus and Pavona gigantea. Coral Reefs 18(1), 29–41.
||Abstract: "The dual character of corals, that they are both auto- and heterotrophs, was recognized early in the twentieth Century. It is generally accepted that the symbiotic association between corals and their endosymbiotic algae (called zooxanthellae) is fundamental to the development of coral reefs in oligotrophic tropical oceans because zooxanthellae transfer the major part of their photosynthates to the coral host (autotrophic nutrition). However, numerous studies have confirmed that many species of corals are also active heterotrophs, ingesting organisms ranging from bacteria to mesozooplankton. Heterotrophy accounts for between 0 and 66% of the fixed carbon incorporated into coral skeletons and can meet from 15 to 35% of daily metabolic requirements in healthy corals and up to 100% in bleached corals." P.2 left column top paragraph: "Since these famous works, numerous studies have confirmed that many species of corals are active heterotrophs (reviewed by Muscatine, 1973, Wellington, 1982, Sebens et al., 1996, Grottoli, 2002,
Houlbre`que et al. 2004a,b, Palardy, Grottoli & Matthews (2005, 2006), and that heterotrophy accounts for between
0 and 66% of the fixed carbon incorporated into coral skeletons (primary sources)."