Answer:
Abiotic conditions would be the temperature of the reef, and also the amount of light that the living organisms receive. (aka coral and zooxanthealle algae)
Biotic would be coral, and also fish. A disturbance in the balance of an abiotic of biotic factor could in turn kill one of the many organisms needed to keep each other alive in symbiosis within the coral reef. In a domino effect, if one organism that is essential to the balance dies, then another, and so on until the coral reef itself dies.
