The Coral reefs of Kiribati consists of 32 atolls and one raised coral island, Banaba (Ocean Island), which is an isolated island between Nauru and the Gilbert Islands. The islands of Kiribati are dispersed over of the Pacific Ocean and straddle the equator and the 180th meridian, extending into the eastern and western hemispheres, as well as the northern and southern hemispheres. 21 of the 33 islands are inhabited. The groups of islands of Kiribati are:
Gilbert Islands: 16 atolls located some north of Fiji. Phoenix Islands: 8 atolls and coral islands located some southeast of the Gilberts. Line Islands: 8 atolls and one reef, located about east of the Gilberts.
The recognizable reef systems in these archipelagos are: 3 reef communities or submerged reefs; 15 fringing reefs; and 18 atolls. In the Line Islands archipelago, Kingman Reef, Jarvis Island and Palmyra Atoll are U.S. territories that are administered as part of the United States Minor Outlying Islands, although they are geographically part of the Line Islands archipelago. Kingman Reef, Jarvis Island and Palmyra Atoll are part of the Pacific Remote Islands Marine National Monument.
The reefs in the Gilbert Islands are exposed to the effects of pollution and over-utilisation of the reef resources by the residents of the islands, which is similar to the threats to the Coral reefs of Tuvalu, which are to the south east of the Gilbert Islands. In contrast, most of atolls of the Phoenix Islands and Line Islands are uninhabited.
The isolation of the Phoenix Islands, most of which are uninhabited, means they are among the most pristine coral reefs on Earth.
Areas of high biodiversity and conservation value
Key Biodiversity Areas
A total of 22 Key Biodiversity Areas (KBAs) - areas of high biodiversity and conservation value - have been identified in Kiribati, with the KBAs encompassing both marine and terrestrial systems (such as bird nesting or feeding environments). The 22 identified KBAs cover an approximate total area of or approximately 74% of the total land, lagoon and reef habitat of Kiribati. As of 2013, 12 of the 22 KBAs have been completely or partially established as conservation areas by the government of Kiribati or by local village communities.
The North Tarawa Conservation Area includes marine zones.
Four marine reserves were specifically set aside for the conservation of grouper. These are all located in the Gilbert Islands on the atolls of Butaritari, Tabiteuea, Nonouti, and Onotoa and are managed by the Fisheries Division.
Phoenix Islands Protected Area
The 2006 declaration of the Phoenix Islands Protected Area (PIPA), with a size of , created, at that time, the world's largest designated marine protected area (MPA), which was also designated as the world's largest and deepest UNESCO World Heritage Site in 2010. The U.S. administered Pacific Remote Islands Marine National Monument is currently the world's largest designated MPA, and is to the north and north-east of the PIPA.
The PIPA constitutes 11.34% of Kiribati's Exclusive Economic Zone (EEZ). The PIPA conserves one of the world's largest intact oceanic coral archipelago ecosystems, includes 14 known underwater seamounts (presumed to be extinct volcanoes) and other deep-sea habitats. The area contains approximately 800 known species of fauna, including about 200 coral species, 500 fish species, 18 marine mammals and 44 bird species. In total it is equivalent to the size of the state of California in the U.S., though the total land area is only .
There are three atolls with associated lagoons and perimeter coral reefs in the PIPA, Orona (Hull), Nikumaroro (Gardner), and Canton Island (Abariringa), and five low islands surrounded by fringing reefs, Manra (Sydney), Rawaki (Phoenix), McKean, Birnie and Enderbury, and also two submerged reefs, Winslow and Carondelet. The area contains seven main habitats: island, lagoon, coral reef, deep reef, seamount, deep benthos, and open ocean, which are all represented within PIPA and the Kanton Island protection zone.
In the PIPA Management Plan 2015–2020, which was implemented following a Kiribati government decision in January 2014, there is a total ban on commercial fishing within the PIPA boundaries extending to the limits of the Territorial Sea (to 12 nm) and in all lagoons of the 8 PIPA islands, (Canton, Manra, Rawaki, Birnie, Mckean, Enderbury, Nikumaroro and Orona) to ensure there is no impact to marine and terrestrial species including habitats.