Both host and algal symbionts respond quickly to food availability (Fitt, 2000). At the algal level, Dubinsky et al. (1990) as well as Titlyanov et al., (2000a,b, 2001) showed an enhancement of the areal pigmentation and zooxanthellae density in fed corals, leading to an increase in the areal photosynthesis. At the animal level, heterotrophy tends to increase the amount of tissue synthesis (Jacques and Pilson, 1980; Sebens and Johnson, 1991; Kim and Lasker, 1998). An enhancement in skeletal growth has also been observed, suggesting that corals allocate a high proportion of the energy brought by food to calcification processes (Jacques and Pilson, 1980; Witting, 1999; Ferrier-Pagès et al., 2003; Houlbrèque et al., 2003). Although it is well known that nutrients are continuously exchanged between the two partners (Muscatine, 1990), few studies have focused on the simultaneous effect of feeding on the algal and animal components (Witting, 1999; Ferrier-Pagès et al., 2003; Houlbrèque et al., 2003).
