Things have been headed south for decades on both land and water. We are in the sixth great extinction of life on our planet, and this one appears to be our doing. Jacques Cousteau revisited areas he first explored many years later and found biodiversity and quantities of life forms greatly reduced. There is no where in the ocean that has not been affected by man. Ocean currents even carry our refuse and pollutants to the antarctic where man's terrestrial footprint has been comparatively light.
My concern, which appears to be playing out, is that the pace of climate changes is faster than the speed with which corals can adapt.