The coastal zone, which can be defined as the region between the seaward margin of the continental shelf and the inland limit of the coastal plain, is among the Earth’s most biologically productive regions and the zone with the greatest human population. It also embraces a wide variety of landscape and ecosystem types, including barrier islands, beaches, deltas, estuaries, mangroves, rocky coasts, salt marshes and seagrass beds. Coral reefs and coastal wetlands are some of the most diverse and productive ecosystems, and 90 per cent of the world’s marine fish catch, measured by weight, reproduces in coastal areas (FAO, 1991). In 1995, over 2.2 billion people (39 per cent of the world’s population) lived within 100 km of a coast, an increase from 2 billion people in 1990 (Burke et al., 2000). This coastal area accounts for just 20 per cent of all land area.