Note
Coral reefs are among the most productive and diverse ecosystems in
the world. They grow as a thin veneer of living coral tissue on the outside
of the hermatypic (reef-forming) coral skeleton. The world's major coral
reef ecosystems are found in nutrient-poor surface waters in the tropics
and subtropics. Early references to coral reef ecosystems preferring or
"thriving" in areas of upwelling or other nutrient sources have since been
shown to be incorrect (Hubbard, D. 1997). Rather, high nutrient levels
generally are detrimental to '!reef health" (Kinsey and Davies 1979) and
lead to phase shifts away from corals and coralline algae toward dominance
by algal turf or macroalgae (Lapointe 1999).