Monday, September 28, 2009

Flat Coral Reefs: the architecture of Caribbean reefs is changing

Healthy coral reefs include a multitude of nooks and crannies that provide a base and secure haven for a variety of organisms - from algae and plants to mollusks, lobster and fish. But according to, a new study released by the University of Anglia in England shows strong evidence that Caribbean reefs are "flattening" and providing a less than favorable architectural structure that threatens the reefs' survival.

Comparing 460 studies done since 1968, the report identifies the reef "rugosity index" which measures the habitats' architectural complexity. An index number of 1.0 is considered flat, while at the other end of the scale (a healthy reef), anything greater than 3.0 is very rare. Apparently most reefs that were studied with an index of 2.5 have now disappeared and 75% of the reefs are around 1.5.

What is causing this? The report lists several potential causes - all naturally induced calamities.
White-band disease in the 1970's (which impacted Acropora coral species), followed by a disease-induced mortality in the mid-80's of a predatory urchin species (though a predator, the urchin serves to keep coral reefs healthy and free from overcrowding; like thinning a forest through natural processes). Then there was coral bleaching in the late 90's, where stressed coral expels its symbiotic algae. All of this could represent the natural ebb and flow of a reef: calamities that the reef could withstand and recover from in time.

But add to that, the impact of human activities - everything from pollution, acidification, excess sediment from land development, destructive fishing practices - and the reefs could be pushed far beyond their ability to recover. The loss of coral reefs would have immediate impact on fish populations (which have been in decline in the Caribbean for years), in addition to impacting commercial fish and lobster businesses. Lastly, the flatten architecture of the reefs would reduce their ability to act as important coastal protection from wave energy, exposing coastal communities to increased wave action, higher sea levels, and greater exposure to hurricanes.

Not only do we need to not threaten reefs with our own activities, but we must actively study and judiciously and carefully protect reefs when they are threatened by natural events to insure their long-term survival . . . and ours.

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