A large-scale experiment to assess the impact of coral bleaching on the composition of fauna living inside coral colonies has begun at the Dambay Marine Research Station of the Russian-Vietnamese Tropical Center (Nha Trang Bay, Vietnam). At a depth of 4 m, carrier frames were installed, on which 400 fragments of Pocillopora coral colonies were planted (Fig. 1-3). During the year, with the help of thermal sensors and photographic recording, observations will be made of the dynamics of water temperature and changes in the color of corals. To control the composition of the fauna, 30 coral colonies will be selected monthly.
It is known that when the water temperature rises above 30ᵒС, corals begin to eject intracellular symbionts - zooxanthellae algae, due to which a brightly colored coral loses its appeal and turns from bright green, purple or brown to white. The effect is known as bleaching. Single-celled zooxanthellae are the main food source for hard corals. If the algae disappear or become scarce, the coral starves and produces less slime. And mucus is the main source of food for specialized symbionts - crabs, shrimps, polychaetes and fish, so it is not only the coral that is starving, but also its inhabitants.