Scleractinian corals are naturally exposed to stresses such as predation by the polychaete Hermodice carunculate, or infection with the cyanophyte Oscillatoria submembranacea. These processes usually remove part of the living tissue of a coral, while the rest of the colony survives. In aquaria experiments, corals were subjected to extreme temperatures, causing a slow deterioration of the specimens. When corals under these conditions were exposed to the natural stresses mentioned above, a process was triggered that led to sudden death of the coral specimens. Starting at the borderline where coenosarc meets wound, the coral-tissue disintegrates rapidly, sloughing off the skeleton in strands or blobs, leaving behind a completely denuded corallum. The phenomenon, which has tentatively been called Shut-Down-Reaction or SDR, is a non-intermittent process, which always results in the death of the entire coral specimen, once it is triggered. SDR was also found to be highly contagious and could conceivably lead to a chain-reaction under certain circumstances. In the field, SDR's triggered by man's interference, were observed in corals under the stresses of extreme temperature, sedimentation, and depth. It is believed that the implications of SDR could pose a considerable problem for coral reef resource management. Reef-corals in certain stress situations do not tolerate additional stresses that are routinely imposed upon them in the day-to-day operation of e.g., an underwater park, and permissible limits of resort-utilization may have to be adjusted accordingly.