About Coral Reefs

Chuuk, Federated States of Micronesia. Photo by K. Kim
Chuuk, Federated States of Micronesia. Photo by K. Kim

Coral Reefs are one of the natural wonders of our planet. In their natural unspoilt condition they brim with life. The intricate and varied coral animals on which the growth of the reef depends create both dramatic steep walls and beautiful coral gardens. All around throng thousands or tens of thousands of fish of numerous shapes and colours, and among the coral branches and boulders are to be found an unrivalled diversity of marine invertebrates – worms, shrimps, crabs, clams and sea snails, starfish and sea-urchins and many more, both large and small. A few turtles here and a pod of dolphin there, and it is not only the dedicated naturalist who finds that this is paradise. Through the growth of snorkelling and SCUBA diving millions of people are now drawn to coral reef around the globe to experience their beauty, enjoy their fascination or relax in such an extraordinary environment.

Subsistence fishing, Unakap, Vanuatu. Photo by N. Pascal

Further, in the form of the fish and shellfish that are nurtured by coral reefs and their associated habitats (such as mangrove forest and seagrass bed), coral reefs also generate considerable food resources. Hundreds of millions of coastal people in tropical and sub-tropical countries depend for their primary source of protein on fish that live on coral reefs or obtain their food from coral reefs. Traditionally these have been caught by artisanal fishers using traps or hook and line or nets, on a sustainable basis. As significantly, the reef also constitutes a living laboratory. They support the greatest number of species of any marine environment and probably harbour the greatest range of animal forms of any habitat on earth. Many are of great scientific interest, or offer opportunities for research into fundamental biological questions, or produce substances, such as pharmacologically active compounds, of great present or future value.

Yet at a now frightening pace these coral reefs, the beauty they create and the resources they produce, are being lost to us. Successive forms of environmental impact caused by human activity have resulted in extensive degradation of destruction reef habitats in many areas.

Coral are killed by the increased amounts of sediment in coastal waters, the result of dredging, coastal infilling, coastal erosion or inland soil erosion. Extensive discharge of inadequately treated sewage or run-off of agricultural fertilisers into coastal waters has promoted growth of algae that overgrow and kill off corals.

Huvadhoo atoll, Maldives. Photo by N. Graham
Drop off at Huvadhoo atoll, Maldives. Photo by N. Graham

Fishing by greatly increased numbers of fishers, using modern boats gear or reef damaging techniques, has frequently produced a collapse in commercial fish populations and even damaged the reef habitats that the fish need to shelter, feed or reproduce.

Outbreaks of huge numbers of several coral-eating or coral-eroding sea-urchins or starfish, most likely occurring as a result of the removal of their predators by man, have depleted corals in many reef regions.

Tourism, while generating added economic value to the reef environment, has frequently damaged both directly and indirectly (through bathers trampling on corals or coastal hotels being built too close to them) the very beauty that visitors come to enjoy.

And most recently it has become clear that the greatly enhanced emission of carbon dioxide and other greenhouse gases caused by man is threatening coral reefs, probably more than any other habitat, both through the slow but persistent rise in sea temperatures and gradual acidification of the oceans, to which effects corals seem uniquely sensitive.

Thus not only are coral reefs a fascinating environment presenting many intriguing questions to the curious scientist, but a resource presenting urgent problems to both scientists and environmental managers, concerning the actions required if these amazing products of nature are to be handed on in good condition to future generations. The International Society for Reef Studies in the principal international association for scientists and managers dedicated to all or any of these issues. It also welcomes naturalists, students and others wanting to know more about coral reefs or contribute to the society’s activities.

Mangroves in Virgin Islands Coral Reef National Monument, St. John, USVI. Photo by C. Rogers