Abstract
Reef-building corals are an obligatory symbiotic system in which symbiont's photosynthesis is essential. It has been reported sometime that many reef-building coral species include endolithic algae within their skeleton. In spite of its potential significance, inter-relationship between endolithic algae and host corals is still obscure. We report here that endolithic algae bring about a positive effect on the host coral Acropora digitifera. In order to investigate effects of endolithic algae to host corals, we compared endolithic algae infected and non-infected groups of A. digitifera. Infected group maintained a higher maximal quantum yield (Fv/ Fm) than that of non-infected at optimal temperature (26ºC and 28ºC). In high temperature conditions (30ºC and 32ºC), however, there were no significant differences between both groups. Recovery rate of Fv/ Fm from damaged conditions was similar in both groups at water temperatures tested.
