Source:
"Studying fossil reefs, scientists determined that Caribbean corals had been declining decades before widespread bleaching and disease outbreaks occurred.
Growing human populations cleared the land for farms, sugarcane and banana plantations.
Resulting soil runoff reduced water clarity required for efficient photosynthesis.
Increased sewage also reduced clarity and introduced pathogens.
Those stressors made coral more susceptible to subsequent bleaching and disease.
Soil runoff also added nutrients that tipped the ecological balance to favor seaweed growth, while over fishing removed seaweed eating fish that once restricted seaweed dominance."