Coral Reefs: Under Siege

by Rodney M. Fujita, Ph.d
Staff Scientist, Environmental Defense Fund

For over two decades, the Environmental Defense Fund has been a national, non-profit membership organization committed to using our unique combination of scientific, economic, and legal skills on behalf of the environment. EDF has been extremely effective in protecting wetlands and estuaries, which are of great importance as habitat for marine life, feeding grounds for birds, protector of shorelines, and processors of nutrients and organic matter for the sea. Our achievements have been based on sound and innovative scientific, policy, and economic analysis aimed at developing solutions to environmental problems. Now, yet another nearshore marine environment is under siege: coral reefs.

Coral reefs are complex and beautiful marine ecosystems that occur in shallow, clear tropical waters around the world between the latitudes 300S and 300N. The approximately 600,000 square kilometers covered by reefs are among the most productive and biologically diverse in the sea.

Coral reefs are highly productive because of the many ways in which they capture nutrients from the environment and recycle them internally. They have grown vertically as the sea level has risen since the last ice age, providing the photosynthetic symbiosis between coral polyps and algae with sufficient light to grown rapidly. Coral reefs transform biologically useless nitrogen gas in the atmosphere to a form useful for coral and plant growth, intercept nutrients from the sea and from ground water, store nutrients in the myriad organisms living on reefs and in the sediments, and recycle nutrients tightly within symbioses and between plants and animals.

The complex mixture of coral species and calcifying algae that make up the reef structure provides ideal habitat for fishes, lobsters, crabs, and a host of other invertebrates. The massive reef structure plays and important role in dissipating the energy of storms and waves, thereby protecting shorelines. Waves, plus parrot fish and other animals that eat into the limestone produced by corals, produce the beautiful white sand characteristic of coral reef areas. The waters around coral reefs are often frequented by hawksbill turtles and dolphins. Sand flats and seagrass meadows surrounding coral reefs provide feeding grounds for many of these organisms and are habitat for rays, dugongs, turtles, conch, and many others.

The extraordinarily high diversity of coral reefs results in ecosystems of exceptional beauty and biological importance. The complex coral reef ecosystem has provided science with important insights into the nature of symbiosis, ecological competition, evolution, and animal behavior. Because the tropics are such a nice place to live, with abundant sunshine and worm temperatures, and because there are so many different kings of organisms living there, the animals and plants of rainforests and reeds seem to be engaged in perpetual chemical warfare. Plants produce chemicals to ward of bacteria, viruses, and herbivores. Animals, especially those that canŐt move around (sponges, tunicates, and the like) produce chemicals to discourage predators. These chemicals include many that are already important biomedical research tools and drugs, and others that show potential to be useful and drugs. These chemicals kill bacteria, viruses, and fungi, and many also exhibit the potential for affecting the immune response and reducing inflammatory responses in mammals. Medicines derived from tropical plants already dominate the pharmaceutical market; one product in four is derived from wild plants.

Although this fantastic property of coral reefs and rainforests ought to provide motivation for saving the habitats and diversity that produce these chemicals, all profits from drugs produced from tropical plants and animals (like the anti-leukemia and Hodgkins disease drugs from the rosy periwinkle flower of Madagascar that produce about $160 million annually) currently flow into corporate coffers, rather than back into the rainforests and coral reefs which produced them, where economic hardship, debt burden, and other factors are resulting in wholesale destruction.

The last decade has witnessed a growing concern for the future of coral reefs worldwide. Until comparatively recently, humans used coral reefs for subsistence purposes only, as sources of food and craft materials. Reefs have come under increasing pressure, as highlighted above, with the development of commercial fisheries, rapidly increasing populations still dependent on a subsistence lifestyle, growth of coastal ports and urban areas, increasing siltation due to deforestation and poor land use practices, and most recently the rapid growth of coastal tourism. The threats to coral reefs have never been greater than they are today.

The inadequacy of current efforts to protect coral reefs is suggested by a recent survey by the Organization of American States (OAS), which noted that while over 120 marine parks have been established in the caribbean to protect reefs, only about 15% of these have been successful. OAS indicates that a large number of these parks exist solely on paper. The inadequacy of existing protection was driven home this past November when, despite the existence of the Key Largo National Marine Sanctuary, the Looe Key National Marine Sanctuary, and other protected areas surrounding the Keys, the regionsŐs coral reefs suffered damage as a result of three serious and preventable ship groundings. Meanwhile, destructive development practices such as the planned construction of an airstrip near the Blue coral Reefs of Shiraho, Japan, and the commercial development of a sensitive ten mile strip of hardwood hammock in north Key Largo continue to proliferate. Additionally, last year the second major incident in three years of widespread coral bleaching has been reported in Jamaica. Widespread bleaching, during which corals lose their beautiful blue, brown, and green colors and turn dead white, may be a harbinger of global warming, and moreover may exacerbate global warming by adding carbon dioxide to the atmosphere.

Fortunately, many of the factors that threaten coral reefs are reversible and preventable. Fishing pressure could be relieved with sustainable fisheries management and mariculture, the cultivations of marine organisms for food and other products. Mariculture could be combined with wastewater treatment to reduce the amount of nutrients entering coral reefs as well as providing useful products such as carrageenan, agar, and natural gas. Toxins such as pesticides and heavy metals could be reduced at their sources or eliminated with new pest control techniques and processing methods. The destruction of reefs to provide building materials could be circumvented by transporting surplus materials from other countries and by new methods of precipitating limestone from the carbonate-rich waters surrounding coral reefs to form pipes and building slabs. Economic incentives derived from pharmaceuticals and other biomedical products originating in coral reefs could be used to offset development pressure and manage reefs in sustainable ways. Deforestation on coastal slopes with resulting siltation could be presented by better forestry techniques. It may even by possible to reduce the effects of the inevitable sea level rise and warmer temperatures due to global warming. Siltation, nutrients, toxins, and physical damage (from divers and boaters) drain energy from corals, as they struggle to deal with these stresses. Removing local stresses might improve the coralŐs chances of coping with longer-tern, inevitable stresses like increased ultraviolet irradiation from a depleted stratospheric ozone layer and global warming. Naturally, the key to protecting reefs from these global environmental threats is to reduce the emissions of chlorofluorocarbons (CFCs) and greenhouse gases (like carbon dioxide from fossil fuel combustion and deforestation) that cause them, and by reforesting the world.

Coral reefs are indeed under siege by everything from snorkelers stepping on living coral to global sea level rise and warming triggered by the greenhouse effect. These powerful factors have the capacity to destroy coral reefs very rapidly. We must act rapidly and decisively. We must act now!

Sources - Nov/Dec 1990 copyright NAUI. All rights reserved.

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