22. Coral Reefs of the Pitcairn Islands

The Pitcairn Islands are a group of four near-pristine small islands which can claim to be some of the most remote islands in the world. Pitcairn, with a land area of just 4.5 km², is the only inhabited island of the four and has a population (in 2011) of about 60. The islands are located in the crystal-clear waters of the central South Pacific at the south-eastern extreme of the Indo-West Pacific biogeographic province. Each island forms the visible tip of a massive, though extinct, submarine volcano, with between 120 and 200 km separating each. The diversity of nearshore marine species around the four islands is low when compared to island groups lying to the west, a fact reflecting the islands’ low latitude (between 24° and 25° S), their isolation, the limited range of habitats and that colonisation has been largely from the west, despite the islands being upwind and upstream of these biologically rich source areas. A total of 87 scleractinian coral species have been recorded from the islands to date (of which 29 belong to the family Acroporidae), together with 353 species of reef fishes (19 Chaetodontidae), 64 species of echinoderm and just over 500 species of mollusc. The islands’ coral reefs do not suffer from the usual threats associated with human interference, largely on account of their isolation; indeed, the islands remain one of the most pristine marine environments in the world. Their nearshore waters have escaped the ravages of modern fishing methods and the degradation often associated with coastal industries. This has led to the Economic Exclusion Zone around the islands being presently considered as becoming a highly protected marine reserve, one of the largest such reserves in the world.