Located just north of Guam in the western Pacific, the Commonwealth of the Northern Mariana Islands is a three-hundred mile archipelago consisting of 14 islands, with a total land area of 183.5 square miles. The principal inhabited islands are Saipan, Guguan, Rota and Tinian. The northern, largely uninhabited islands are Farallon de Medinilla, Anatahan, Sariguan, Gudgeon, Alamagan, Pagan, Agrihan, Asuncion, Maug Islands, and Farallon de Pajaro. Saipan is approximately 3,300 miles west-southwest of Honolulu and 3000 miles north of Sydney. The majority of the CNMI's residents live on Rota, Tinian, and Saipan, the capital and largest of the Northern Mariana Islands.
The Mariana Islands are on the edge of the Philippine Plate. They were formed by underwater volcanoes along the Marianas Trench. The northern islands are high volcanic islands and the southern islands, while volcanic in origin, are capped by uplifted limestone derived from coral reefs. The southern islands have the oldest and most developed reefs in the CNMI, which are predominantly located along the western (leeward) sides.
Saipan has the most diverse types of coral reefs and associated habitats in the CNMI. A fringing and barrier reef system protects the majority of the beaches along the western side of the island, forming a 12.4 square mile shallow-water lagoon system. This environment contains large assemblages of seagrass, branching corals, and the last remaining mangroves in the CNMI. The western side of the island is the most populated and the coral reefs along these areas are negatively affected by human activity. Continuing sediment and nutrient pollution, combined with sporadic stressors such as outbreaks of crown-of-thorns starfish (COTS) and bleaching, affect many of Saipan's western and southeastern reefs. These impacts are compounded by an expanding tourism industry and direct damage from heavy visitor use.
Coral reef ecosystems in the CNMI are, on the whole, reasonably healthy. However, environmental stressors acting along with anthropogenic stressors, such as nonpoint source pollution and fishing pressure, have clearly affected areas in proximity to the populated southern islands. From a fisheries perspective, the northern islands and more distant banks and reefs appear to be in better condition than those closer to population centers.
