Since the disappearance of sea urchins from the waters up the coast of South Florida, many coral reefs there have been smothered by the uncontrolled growth of algae.

The reefs here are beautiful, but if the sea water is polluted, the coral will die.

Warmer sea temperatures caused by climate change and periodic El Nio events have caused large areas of coral to be wiped out in so-called "bleaching" events.