Everything in the Ocean is Downstrem of Everything Else
Reefs are highly adapted to grow slowly, and require very little in the way of external nutrients. But they need clear water in order to thrive. Land-borne, ocean-borne, and airborne pollution all make their way to reefs and threaten this delicate equilibrium.
Poor Water Quality is the #1 Culprit
Most scientists agree that the greatest threat to Florida's reefs is degraded water quality. This has many causes, most of which relate to human activities, both accidental and deliberate. When land is cleared for development or agriculture, fertilizers, pesticides, and eroded soil wash out to sea when it rains. Pesticides can weaken the corals and make them more susceptible to disease. Sediments can smother or scour the reef, impairing coral growth. The sea is also where most of the sewage and wastewater from Florida Key residents and their one million annual visitors ultimately ends up, and this pollution also degrades the water quality.