Living coastal resources are found within major coastal ecosystems consisting of coral reefs, mangroves, seagrass beds, benthic systems, and estuaries or lagoons. Coastal ecosystems, particularly estuaries and inshore marine waters have the highest rate of primary production as compared to terrestrial and oceanic regions. Daily gross production rate in terms of grams of dry organic matter per square metre area for the narrow coastal band ranges from 10 to 25, with all other regions having substantially lower values (2). The coastal band conveniently thought of as the transition area between land and sea, holdsthis great diversity of ecosystems, each characterized by its own unique ecological feature. Conditions here may be harsh with wide fluctuations in temperature and salinity, but because of the abundance of food supply, these areas can and do support a high diversity of species which have become efficiently adapted to the widely fluctuating environmental conditions. These ecosystems remain productive because of tidal action which circulates food and nutrients rapidly and efficiently and at the same time washes away waste materials. They also serve as efficient nutrient traps of the continuous nutrient input washed down from land. Within these ecosystems, the autotrophic and heterotrophic layers are maintained in close contact so that energy transfer is more direct and better utilized. Primary productionoccurs all year round especially in the tropics, and the diversity of plant life (phytoplankton, benthic microflora, macroalgae and seagrasses) ensures a high primary production rate. A review of primary productivity rates of various ecosystems showed that the values for coastal ecosystems were far greater than for those of land, freshwater or the open ocean.
The average gross primary productivity (gm C/m2/year) was 2300 to 5074 for mangrove forests, 4650 for tropical seagrass beds, 4200 for coral reefs and 3836 for tropical algal communities (3). Although the deeper open seas of the ASEAN region are not as productive as in temperate areas (except in areas of upwelling), the shallower inshore areas are extremely productive. The coastlines of the six ASEAN countries combine to form a total estimated length of 85,523 km. This is made up of 54,716 km f or Indonesia, 22,540 km for the Philippines, 4,675 km for Malaysia, 3,219 km for Thailand, 193 km for Singapore (4) and 180 km for Brunei Darussalam (estimated from maps). Such extensive coastlines provide a vast potential for the variety of coastal and nearshore marine ecosystems. This potential is recognized as being greatest in the East Asian Seas region (covering the six ASEAN countries) than in other parts of the Indian Ocean region (5).
EXTENT, UTILIZATION AND MANAGEMENT NEEDS
Coastal development in the ASEAN region is extensive with over 70% of the combined populations of the six countries concentrated in coastal villages or towns. Industrialization of coastal areas and offshore islands has been the trend, as the siting of industries in coastal areas makes them within easy reach of port facilities. With this development, coastal areas have become rapidly urbanized, placing a great strain on the coastal environment and its living resources as wastes are discharged in ever-increasing amounts.
Some countries have implemented strict waste treatment measures in order to prevent excessive pollution of the coastal environment. Many of the ASEAN nations depend on tourism as an important source of revenue and develop coastal environments to attract tourists. Beaches have therefore been developed for recreation and tourism, and new unexploited coastal areas are constantly being investigated for such development. As the values of coastal living resources become well understood, some countries have designated reserve areas along the coastal...