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The Palau Marine ecoregion contains some of the most intact examples of open Pacific coral atolls in the world, and has several unique marine habitats. For thousands of years, volcanic islands in the Palau Marine ecoregion have been slowly sinking into the sea, forcing surrounding reefs to grow higher. After the land has finally disappeared beneath the surface, only reefs and lagoons remain. These remarkable structures, known as atolls, look like saucers of water with coral reef rims.
Warm, clear, shallow waters surround Palau's many islands, helping 300 species of coral grow in some of the richest and most diverse reefs in the world. Most of the ecoregion's volcanic islands have become atolls, but some remain and are surrounded by a 70 mile- (110 km-) long barrier reef. These reefs are paradise for communities of coral, fish, and marine mammals. In this area, where reefs have steep drop offs, there are differing levels and speeds of ocean currents. These differing currents lead to many different temperatures and light zones, which contribute to high species diversity. All of the seven known species of giant clams grow on sandy patches of ocean bottom scattered among the coral. Hawksbill, green, leatherback, olive ridley, and loggerhead sea turtles swim among the corals and sea grasses but lay their eggs on shore. Finless porpoises and Blainsville beaked and ginko-toothed beaked whales are frequently seen in this ecoregion. The pyramid butterfly fish found here gets its name from a pearl-colored pyramid shape on its middle. This fish and the endemic Bartlett’s anthias swim near reefs.
Overfishing and fishing with dynamite and cyanide threaten reefs. Outbreaks of crown-of-thorns starfish have occurred. Sewage, runoff, road development, coastal dredging, and the use of reef materials for construction are all serious problems. Oil spills and insecticides harm reef species, and turtles and other animals are hunted. Commericial shark fishing is depleting populations, and tourists stepping on reefs causes damage.
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