139736eo.pdf (20MB) - Japan Oceanographic Data Center

central are corals to the integrity of the reef community that, when they are selectively killed, migrationor death of much of the other reef fauna ensues... therefore, the environmental tolerance of the reefcommunity as a whole cannot exceed those of its corals”.UTILIZATION OF CORAL REEFSEXTRACTIVE USESTraditionally, many coastal communities dependant and/or associated with coral reefs haveharvested the productivity of the reefs. Food in the form of fish, molluscs, crustaceans and seaweeds,ornaments and materials for hunting and fishing, building materials, fertilizers, and more recentlyaquarium fishes and invertebrates, as well as pharmaceutical chemicals, have been obtained from coralreefs. So long as Maximum Sustainable Yields are not exceeded, it is generally possible for a coralreef to cope with the demand for these products and recover in an ecological sense. However, thehealth of a reef is also crucial for the continued extraction of these resources.NON-EXTRACTIVE USESThe most obvious asset of coral reefs is their fascinating beauty. The innumerable colourfulfishes, shells, fan-worms and other organisms give tropical seas a romantic image which has beenenhanced through the growing popularity of skin and scuba diving and exposure through the visualmedia such as movies and television (BETTERTON and DE SILVA, 1979). Maldive Islands and SriLanka have started to exploit the natural beauty of their coral reefs and associated beaches byestablishing tourist resorts around such areas. Although local residents have been slower than touriststo use coral reefs for recreation, they have benefited by the opportunities for employment and othermeans of socio-economic improvement created by tourism.Coral reefs represent a uniquely productive tropical ecosystem (MATHIAS and LANGHAM,1975; DAHL, 1974; SOROKIN, 1973) that is important to fisheries (SMITH, 1978; STEVENSONand MARSHALL, 1974; ALACALA and LUCHAVEZ, 1981) and tourist industries, as well asproviding breeding and nursery grounds of several marine organisms (summarised by DE SILVA,1983). A coral reef also provide a natural storehouse of species for scientific research andinvestigation. In addition, they can be used as instructional tools in both formal and non-formaleducation. Coral reefs are natural laboratories which provide the opportunity for observing livingexampIes of principles established in the classroom.Establishment of marine parks can be a major non-extractive use of a coral reef. In addition toproviding a means to monitor of a reef, a properly organized and managed marine park can generate anincome and provide opportunities for socio-economic improvement by offering several supporting andrecreational facilities such as scuba diving, snorkelling, tours in glass-bottom boats and similarwater-based activities.ENVIRONMENTAL PROBLEMS OF CORAL REEFSFactors causing the degradation of coral reefs in South Asia can be considered under twoseparate categories: natural causes and man-made causes. As stated by GOMEZ (1981), “... inpractical situations it is sometimes impossible to separate the effects of the two, because they areintertwined in a complicated and dynamic way with the multitude of factors and processes thatcharacterize the exceeding complexity of coral reefs as ecosystems”.154