It's not just Florida but the majority of the Caribbean that now looks that way. What's changed in the past 20-30 years? You can point to the mass explosion in the human population growth - and that brings about the massive coastal developments, more pollution, sedimentation, runoff, overfishing - and yes, increase in sea surface temperatures. Basically, things that everyone in this thread has already discussed.
The Caribbean and tropical western Atlantic is essentially a ring of development from Florida/Bahamas down to Brazil. Unfortunately, there is a direct negative correlation between the distance a coral reef is to human disturbance and overall reef health - as measured in total coral coverage, fish size/density, etc.
Compounding this is the largest epizootic ever known - the loss of the Diadema urchins that started in Panama in 1983, where the pathogen rode the currents. The loss of this herbivore was quite possibly the last stability pin that was pulled from Caribbean reefs leading to their collapse - though they were probably already tinkering on the edge collapse as fully-functioning ecosystems.
Taking a water sample now likely won't do much good. Elkhorn and Staghorn corals have collapsed from a combination of stressors, fueled by coral bleaching and the resulting diseases that ravage corals after a bleaching event.
In addition, Florida likely seems particularly hit b/c its populations of Elkhorn and Staghorn seem to have reproduced primarily through asexual breakage rather than through sexual reproduction. This has left that population genetically depauperate and, thus, less resistant to disease.
Basically, in my lifetime, Caribbean and western Atlantic reefs have shifted from primarily coral dominated ecosystems to algal reefs, and today we are now starting to see the collapse of that 3-dimmensional structure that the corals have built up since the last ice age. This phase shift is the new face of Caribbean reefs and one that will not change in our lifetime. I simply cringe when I hear new divers coming up from a dive and saying how great the reef looks - with a few corals here and there, a beach-ball size elkhorn colony over there, and vast fields of dictyota and microdictyon algaes everywhere. This is the shifting baseline we must prevent. Basically... it shouldn't look like this.
It is also my feeling that if reefs only had to cope with increasing sea surface temperatures, they would have a better fighting chance. But with a combination punch of 4, 5, 6, 7 and more stressors piling on them all at once, it's just simply too much to overcome. Will every species of coral go extinct? Likely not. But, as others have mentioned already, the face of reefs in the future will change drastically. Heck... it's already here.
7 billion people... and there are tv shows that glorify 8 and more plus children per family............
Cheers
Mike
