It is fairly simple, they do not die in the same temps when the PPM of these chemicals are low, the temps are secondary and are allowing the chemicals to make c

It is fairly simple, they do not die in the same temps when the PPM of these chemicals are low, the temps are secondary and are allowing the chemicals to make certain bonds that are toxic to the reef. Absent the chemicals the reefs tolerate the temperatures just fine. They are only sensitive to temperature when the chemicals are present thus the chemicals are the primary source of death and thus their elimination is paramount to the survival of reefs. The chemical are what kill the coral not the temperature as if you heated the water to threshold, then cooled it, then poured it on coral it will kill it as the water has reached threshold, thus the bonds have been made. This study was actually done here in the keys, I will see if I can find the paper. Both agricultural run off and sunscreen follow a similar pattern.