Decline of Florida's Reefs is Not a Mystery

John C. Ogden & Steven L. Miller

A recent Associated Press report (Not Clear Why Florida's Reefs Dying, February 4, 2001) asserts that the dramatic loss of living coral cover on the reefs of the Florida Keys over the past two decades remains mysterious in spite of a great deal of research. In the article, prominent scientists advance their pet theories-- one says that reefs are killed by sewage and fertilizer, another by diseases, and another by coral bleaching. Still others say we simply don't know. Unintentionally this apparent confusion calls into question the ability of science to provide clarity and direction for expensive and politically contentious efforts to manage the economically significant environmental resources of Florida.

The fact is that science has already provided us enough understanding to act. The Keys reefs are identical to coastal areas all over the world in suffering from the multiple and additive impacts of relentlessly growing human populations. The list is short: poor water quality from land-based sources including sewage, fertilizers, and sedimentation; over-fishing; and global climate change. In Florida, these problems are exacerbated because the natural environmental setting includes significant natural stresses, including hurricanes, summer high temperatures, and winter cold fronts, all of which kill corals.

The management plan of the Keys Sanctuary, established over 6 years of effort with the best available scientific information, contains action plans to deal with local human disturbances. It is moot whether or not nutrients from sewage and fertilizers are destroying offshore coral reefs. Nearshore water quality in the Keys has declined to the point where it fails to meet minimal standards for human health. The management plan contains long-term provisions to revise the requirements for sewage disposal and land runoff in the Keys. It will be a long term and expensive proposition, but few seriously deny that it is absolutely essential.

Decades of over-fishing of top predators such as groupers, snappers, and sharks have destabilized the coral reef system. The management plan has already implemented a series of 23 small, fully protected marine reserves, prohibiting all extractive use. We can be encouraged that the Fish and Wildlife Conservation Commission has recently approved a large marine reserve in the Dry Tortugas. Research all over the world has shown unequivocally that fully protected marine reserves are our best chance for sustaining not only fishes, but also the myriad smaller reef organisms. We predict that as protected reefs show recovery, the use of marine reserves as a tool for maintaining healthy reefs will gain acceptance.

Global climate change, the third major human disturbance in our short list, cannot be managed on a local scale. Coral bleaching, perhaps the first signal of global warming in the oceans, occurs during prolonged, late summer, high seawater temperatures that, in turn, often coincide with an increasingly familiar global disturbance-the El Ni(o. While severely stressed, bleached corals can often recover.

There is good scientific evidence that tropical oceans are warming and that coral bleaching events are increasing in frequency, extent, and severity. Backed by the scientific consensus and alarming projections of the just-released second report of the Intergovernmental Panel on Climate Change, global warming is the focus of strenuous and contentious international efforts to control the emission of greenhouse gases.

Does scientific uncertainty about natural variation and global climate change obviate our responsibility for local management? Our coral reefs as well as our own bodies react to multiple stresses by declining health. Common sense tells us that minimizing the whole range of stresses will strengthen the natural system as the human one. In other words, well-managed local reefs may prove to be more resilient to stresses, such as global climate change, which are difficult to predict. We must confront the illusion that science can always provide the answer, and use the excellent information that science has already provided to take obvious steps to protect our coral reefs.

The tragic history of resources exploitation is over-exploitation, and the Keys are no exception. Drawn to gin clear waters and abundant resources, early residents, tourists, fishers, and businesses found an earthly paradise, which attracted others until over-development and the decline of the Keys universally valued attributes, particularly its clear waters and coral reefs, was obvious to everyone. The coral reefs, seagrass beds, and mangrove forests of the Florida Keys National Marine Sanctuary are unique in the continental U.S. and critical to Florida's tourism-based economy. There is no mystery in what happened to them nor is there any mystery in the painful, contentious, and expensive steps that we must take to restore them.

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John C. Ogden is Director of the Florida Institute of Oceanography in St. Petersburg, which operates the Keys Marine Laboratory on Long Key in partnership with the Fish and Wildlife Conservation Commission. He is on the boards of the Center for Marine Conservation and the World Wildlife Fund.