Marine, Coastal and Island systems
"Marine systems are the world’s oceans. For mapping purposes, the map shows ocean areas where the depth is greater than 50 meters. Global fishery catches from marine systems peaked in the late 1980s and are now declining despite increasing fishing effort.
Coastal systems refer to the interface between ocean and land, extending seawards to about the middle of the continental shelf and inland to include all areas strongly influenced by proximity to the ocean. The map shows the area between 50 meters below mean sea level and 50 meters above the high tide level or extending landward to a distance 100 kilometers from shore. Coastal systems include coral reefs, intertidal zones, estuaries, coastal aquaculture and sea grass communities Nearly half of the world’s major cities (having more than 500,000 people) are located within 50 kilometers of the coast, and coastal population densities are 2.6 times larger than the density of inland areas. By all commonly used measures, the human well-being of coastal inhabitants is on average much higher than that of inland communities.
Islands are lands (both continental and oceanic) isolated by surrounding water and with a high proportion of coast to hinterland. For mapping purposes, the MA uses the ESRI ArcWorld Country Boundary dataset, which contains nearly 12,000 islands. Islands smaller than 1.5 hectares are not mapped or included in the statistics. The largest island included is Greenland. The map above includes islands within 2km of the mainland (e.g., Long Island in the United States) but the statistics provided for island systems in this report exclude these islands. Island states together with their exclusive economic zones cover 40% of the world’s oceans. Island systems are especially sensitive to disturbances, and the majority of recorded extinctions have occurred on island systems, although this pattern is changing, and over the past 20 years as many extinctions have occurred on continents as on islands."
Source & ©
Millennium Ecosystem Assessment
 Synthesis Report (2005),
Chapter 1, p.27
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