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The northern island areas of the Central and Western Pacific are characterized by widely scattered archipelagos of relatively small islands. Reefs are well developed throughout the region, except on the coastlines of recently active volcanoes. Palau lies closest to the center of reef diversity in the Philippines and Indonesia, and shows very high levels of species diversity. Biodiversity declines to the east.At the present time there is considerable differences both in the state of the reefs and the impacts of human cultures. The influence of the USA, associated with rapid Western-style development, is considerable in a number of countries, notably Guam, but also in parts of the Marshall Islands. Urban growth on a few islands has brought with it the breakdown of traditional systems  and the sustainable utilization of resources, together with associated problems of pollution. Military activities have also had a considerable impact in the region. Intensive nuclear testing during the 1940's and 1950's impacted a number of Map of the Federated States of Micronesia (Political), 1999. Courtesy of, The World Factbook ( or CIA Maps and Publications Released to the Public (, Central Intelligence Agency (CIA), Government of the United States of America (USA); and the Perry-Castaņeda Map Collection (, Perry-Castaņeda Library, The General Libraries, University of Texas at Austin, Austin, Texas, USA.tolls in the Marshall Islands, with repercussions to the present. There is also ongoing utilization by the USA of some islands and reefs in the Marshall Islands and the Marianas for military purposes, including target practice. Tourism is a critical and growing economic activity in a few islands, notably Guam, Saipan and Chuuk Atoll. Away from areas of human impact, the region still includes a very large number of islands and reefs in good to excellent condition, where the traditional use of the reefs by local peoples remains sustainable and well managed.

Commonwealth of the Northern Mariana Islands & Guam
The Mariana Islands forma a long chain of 15 high islands in the Western Pacific, running approximately 800 kilometers from Faraloon de Pajaros (Uracas) in the north to Guam in the south. The southernmost island of Guam is an unincorporated territory of the USA, while the remaining islands, the Commonwealth of the Northern Mariana Islands, are a commonwealth in political union with the USA. Guam is the southernmost and largest of the islands, and is entirely circled by fringing reefs.

The Mariana Islands, lying relatively close to the center of coral reef biodiversity in the Philippines and Indonesia, enjoy high diversity. Guam, which is fairly well studied, has about 300 recorded species of scleractinian corals, 950 species of reef fish, 220 species of benthic algae and more than 1,400 species of mollusks. Both diversity and cover decrease considerably in the geologically younger northern islands where the geological conditions are unfavorable for many species, while in the far north cooler conditions may further restrict certain species.


Natural pressures on the reefs around Guam have been greatly exacerbated in recent years by human activity. Agriculture, development and the burning of natural areas have led to increased sedimentation in the surrounding waters, while over fishing is widespread and total catch per unit of effort reportedly feel by 78 percent between 1985 and 1997. The overall impact on the reefs has been considerable.  Coral cover is reported to have dropped significantly since the 1970's, when it was over 50 percent in many areas.

Human pressures are largely focused around the urban areas of the barrier reef system in western Saipan, but also at Rota West Harbor and San Jose Harbor on Tinian where there are problems of pollution and sedimentation. Overfishing is believed to be occurring on Saipan and Tinian, where fisheries data show low average sizes of many reef species. Finally the island of Farallon de Medinilla has been extensively used for target practice  by the U.S. military. Local objections have been raised, with campaigns to have this activity restricted or moved to one of the more active volcanoes where the impacts may be less detectable. Thus far no serious efforts to relocate have been made.

The economy of both territories is highly dependent on tourism. Guam receives more than 1.4 million visitors per year, while the CNMI receives about 500,000, primarily limited to the island of Saipan. Diving and snorkeling are popular tourist activities. Research on the reefs is well advanced, particularly in Guam where there is an active marine laboratory associated with the University of Guam. Several protected areas have been established, included a number of coastal and marine sites in Guam and some in the CNMI.

Relevant Websites:
Commonweath of the Northern  Mariana Islands Coastal Resources Management
Commonwealth of the Northern Mariana Islands Division of Environmental Quality Website
. Guam

Welcome to Guam


Palau & the Federated States of Micronesia
Palau makes up the western end of the Carolina Islands. It is dominated by a large complex of islands and reefs, consisting of the Kayangel Islands in the north; the large island of Babeldaob (Babelthuap) in the center; and the Rock Islands (Chelbacheb Islands) to the south. Coral reefs are widespread. Most of the northern islands are concentrated on a single shelf fringed by a well developed barrier reef of some 290 kilometers in length. In the southern parts of the lagoon there is a considerable number of fringing and platform reefs. North of this large platform, Kayangel and Ngaruangel are both atolls. To the southeast of this main group of islands there are several widely scattered ones. These are mostly platform islands (Fana, Sonsoral, Pulo Anna and Tobi), although Merir and Helen Reef are atolls with a single island on each. Helen Reef has a partially submerged rim.

The climate in Palau is warm and generally humid. From November to June the northeasterly trade winds dominate, but for much of the rest of the year winds are lighter and more variable, although occasional typhoons also occur around this time.

Levels of biodiversity are very high. Some 425 species of coral have been reported , including an estimated 300-350 stony corals, together 1,278 species of reef fish and well over 300 species of sponge. The southern reefs are swept by strong currents and dominated  by blue coral Heliopora coerulea, however they are also very diverse. Helen Reef was recorded as having 248 stony coral species, perhaps the highest number for any Pacific atoll. Coral cover in all areas was high prior to 1998, typically over 50 percent and reaching 70-80 percent on outer reef slopes in many areas. Marine turtles are relatively common and the estuarine crocodile Crocodylus porosus and dugong Dugong dugon are found in the lagoon. There are important areas of mangrove and seagrass Dugongcommunities. One interesting and perhaps unique ecosystem in this country is found in the large number of marine lakes.. These are inland but appear to be connected to the ocean by cave systems and have developed highly distinctive communities which appear to have evolved  in situ from species that entered the lakes in larval forms. The most distinctive of such organisms are the jellyfish, notably Mastigias spp. which have formed vast communities. Marine lakes are most common on Koror where there are 58, of which 28 have jellyfish. The Reefs of Palau were heavily impacted  by crown-of-thorns starfish outbreaks in 1977 and recovery was reported to be poor, even  into the 1990's. The reefs were further impacted by the bleaching event of 1998,with mortality reaching over 50 percent in most areas. Acopora was devastated almost everywhere, but other corals showed slightly higher levels of survival in nearshore lagoons and fringing reefs. The warm waters of 1998 also had a dramatic impact on jellyfish populations in some of the marine lakes, although they now appear to be recovering.  The crown-of thorns starfish has had a number of outbreaks, and high densities in some areas may be exacerbating the setbacks caused by bleaching-associated mortalities.

The majority of the Palauan population live on Koror, but numbers are growing rapidly and there is some expansion to the other islands. Management of marine resources is devolved to the state level. The individual states (of which there are 16, each typically incorporating several villages) have ownership  of all living and non-living resources out to 12 nautical miles, with the exception of highly migratory species. Although traditional law is upheld in the constitution it has been combined with Western statutes, and respect for traditional systems is diminishing. Several of the islands are connected by bridges and causeways which have interfered with natural water circulation in some areas. Sewage and solid waste disposal are a localized problem.

Palau Islands

Fishing is at the subsistence level is very important, but there are also some export fisheries, including a trochus fishery and a large marine ornamental fishery. There is considerable evidence of overfishing of certain target species, notably groupers, and a number of these are showing declines in abundance and changes in demographic structure. In the southwestern islands there have been reports of blast and cyanide fishing.

There is an active interest in conservation in the country. Protected area legislation is developed at the state level, but a number of sites have been established with regulations ranging from seasonal closures and other fisheries restrictions to strict reserves with no entry permitted. For the most part there is strong community support for these areas. The Ngaremeduu Conservation Area has also been recently established covering parts of three states on the west coast of Babeldaob. Legislation has had to be passed in each state to protect this site. Additionally, the American-based organization, Center for Ecosystem Survival, has an innovative "Adopt A Reef" program for sponsorship to help protect Palau's coral reefs.

The Federated States of Micronesia consists of a vast and scattered chain of islands stretching some 2,900 kilometers from east to west. Politically they are independent, but remain in a "compact of free association" with the USA. Although the total area is small, there are some 600 islands with diverse geological origins. The total reef area is very large indeed, over 5,000 square kilometers, but remains very poorly known.

Biodiversity is slightly lower than in Palau, with decreasing diversity moving from west to east. Reef status throughout the country is through to be good. Mangrove communities are particularly well developed around the coastlines around the islands of Pohnpei and Yap. The reefs are of critical importance as a source of food throughout the country. Close to urban areas there is some overfishing and there have been problems with blast fishing. Clams, in particular giant clams, are declining and have been completely eliminated in some areas. Coastal development and associated pollution are again localized problems on the largest islands, but for the most part the reefs remain in good condition. Many reefs are owned and managed at the level of the individual villages. There are no permanent protected areas other than a few small trochus sanctuaries.

Tourism is growing with considerable speed in a few islands, although the more remote islands remain largely unvisited. Chuuk Lagoon is widely regarded as one of the world's top dive centers on account of the very large number of wrecks which sunk in the lagoon during World War II.  About 50 Japanese ships, plus numerous Japanese and American aircraft went down during a two-day American attack in February 1944.

Relevant Websites:
Center For Ecosystem Survival: Adopt A Reef Palau
NOAA Center For Coastal Monitoring and Assessement: Coral Reef Report -Palau
PBS Readers Digest Edens: Palau

Marshall Islands
The Marshall Islands are a complex of 28 coral atolls and 5 small (non-atoll) islands lying in two broad chains, the eastern Ratak (sunrise) chain and the western Ralik (sunset) chain. In all there are some 1,136 islands dispersed over a vast area of ocean, although the land area is very small. The atolls are typically circular to elliptical with shallow lagoons. Kawajalein, at some 2,500 square kilometers, is the largest atoll in the Pacific.

The location of the Marshall Islands places them in an area of fairly high diversity, while the relative lack of pressure on many of the reefs means that there has been little biodiversity loss. Nearly 250 coral species have been recorded at Bikini Atoll, and over 250 species of reef fish are noted. There are important seabird populations, particularly in the northern atolls, with at least 15 breeding species among the 31 recorded in the islands. Some 27 species of whale and dolphin have also been recorded.

The Marshall Islands form a politically independent state, but exist in a "free association" with the USA. Two thirds of the population live on Majuro and Ebeye where they are concentrated into a relatively small area. Consequently there are various environmental problems, including sewage and solid waste pollution. Much development has taken place with little concern for the environment, and the mining of lagoon sand to obtain building materials is widespread.

Perhaps the best known "use" of the atolls of the Marshall Islands was nuclear testing by the USA in the 1940's and 1950's, when some 67 nuclear detonations were performed on Bikini and Enewetak atolls. A study carried out in 1994 confirmed that some 15 atolls and islands were subject to some radioactive fallout during the 1950's, although most of them are now considered clear. The detailed impact of these tests on the coral reef environment  are still unknown, although there were obviously important significant physical affects in the areas of direct impact, while a number of large ships were also sunk in the atoll lagoons.

Although there is a considerable amount of environmental legislation, enforcement is limited. Two protected areas (Bikar and Bokaak Atolls) were established prior to independence but have not been re-established and hence are not recognized officially.

Relevant Websites:
NOAA Center For Coastal Monitoring and Assessement: Coral Reef Report -Marshall Islands

Kiribati & Nauru

Kiribati's islands and coral reefs straddle a vast swathe of the Pacific Ocean but consist of only some 33 islands or island systems. These are typically divided into three broad groups. Most of the actual islands are now referred to by their Micronesian names, although the island groups are still largely referred to by their European names.

The atolls comprise a typical diversity of habitats, including channels, lagoon reefs and shallow reef flats as well as reef slope environments. There is a clear difference between windward and leeward sides, with the windward (eastern) sides typically having a continuous reef margin, narrow reef flat and well developed islands. The leeward reefs are typically much wider, but in some places show a more gradual slope with a less developed reef flat, often submerged at low tide. Spur and groove formations are on all sides, but are usually best developed on lee shores.

Given  the wide geographic spread of this country it is possible to follow some of the wider regional trends within the country itself, notably the diminishing species diversity moving from west to east. Some 115 hard coral species have been recorded from Tarawa and Abaiang Atolls in the west, while Tabuaeran in the east has 71. Blue coral Heliopora coerulea is reported to be widespread in the west despite being uncommon over nearby areas in the Pacific. Coral cover on the outer reef slopes is typically very high, with measurements on Tarawa and Abaiang of up to 57 percent cover at 3 meters depth and 28-72 percent at 10 meters.  Much of the remainder of the benthos is dominated by coralline algae. There are several very important seabird nesting colonies in the Phoenix and Line Islands, with many millions of birds, including the Phoenix petrel and the Polynesian storm-petrel.

The population of Kiribati is low and almost entirely concentrated in the Gilbert Islands. Elsewhere most of the islands are uninhabited, in many areas because freshwater is not available. Most of the islanders are heavily dependent on fish as a source of protein, and over fishing  is a localized problem near population centers. Reports of increasing incidence of ciguatera poisoning have been linked to other environmental disturbances including the dredging of channels and construction of causeways, although these links remain unproven. Locally, notably in the Tarawa lagoon, sewage pollution may be a problem.

Other threats to Kiribati's reefs include causeway construction, possible introduction of non-native species and phosphate mining. Perhaps the greatest threat is that of sea-level change as a result of global warming. Despite this list of threats, the majority of reefs in this coral reef nation are in excellent condition. A number of protected areas have been established. Although they do not incorporate significant marine elements, they do ensure that wider ecosystems are not disturbed.

Nauru is a single island country lying in considerable isolation to the west of Kiribati. Geologically it is a raised coral atoll reaching a maximum height of 71 meters. Surrounding the island is a continuous fringing reef with a reef flat up to 300 meters wide. The biodiversity of the reefs have not been extensively surveyed but the coral fauna is considered to be highly diverse. No seagrasses and only one species of mangrove have been recorded.

On land the entire surface of Nauru has been transformed by phosphate mining, with much of the island now unusable and the population concentrated close to the coast. Although mining is the main source of income the closure of mining operations is planned in the very near future.  Fishing is still an important activity, and there are reports of certain species becoming rare as well as average size of  some fishes diminishing. One impact of the mining industry has been the loss of traditional environmental knowledge. At the same time there are few formal legal controls on reef utilization under the existing fisheries legislation, and no protected areas.. Sewage pollution and solid waste are significant problems.


World Atlas of Coral Reefs

Extracted and adapted from The World Atlas of Coral Reefs, by Mark D. Spalding, Corinna Ravilious and Edmund P. Green, published by the University of California Press . For more complete and in-depth coverage of the topics presented in this webpage, I recommend highly purchasing a copy of this beautifully illustrated book. Just click on the University of California Press link above to do so.