Status of Coral Reefs of the World 2000

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Status of Coral Reefs of the World: 2000 Northern Marianas There have been some systematic studies of the coral reefs of Saipan, Tinian and Rota, but only occasional environmental impact assessments of the other islands. These provide useful ‘snap-shots’ of particular areas, but do not provide long-term monitoring data. The reefs near the southern populated islands of Saipan, Tinian and Rota are of greatest concern as they receive the bulk of anthropogenic impacts from development, population growth, fishing and tourism. The western side of Saipan has a well-developed lagoon with seagrass beds and several pinnacle and patch reefs that are unique to the CNMI. Extensive fringing and apron reefs occur on the northern and eastern sides of the island. Tinian has narrow fringing and apron reefs around most of the western side of the island and at Unai Dankulo on the eastern shore. Small patch reefs occur near Tinian Harbour off Tachogna and Kammer beaches. Well-developed fringing reefs occur along most of the north-west coast of Rota, with narrower fringing reefs found in Sasanhaya Bay and the southern coast. In addition to these, there are a number of submerged sea mounts and shoals in the waters surrounding the CNMI which probably have growing reefs. The coral reef area is estimated at 579km 2 including the offshore banks and shoals. There are 254 hard coral species, with higher diversity in the Southern Islands where reefs are older and more developed. Coral cover in the inner reef zone and most reef flats on Saipan tends to be patchy with lower species abundance and distribution than on the reef fronts and terraces, probably because these areas are stressed by high variations in temperature and salinity. The detailed surveys on Maug in the northern islands show lower coral diversity, with only 74 species. The southern islands had a crown-of-thorns starfish (Acanthaster planci) outbreak in the late 1960s, at the same time as there were damaging outbreaks on Guam. There were smaller starfish outbreaks in the mid 1980s on Saipan, however, the starfish have not been a major problem recently, and most of the reefs appear to be recovering. FSM Reef status throughout the FSM is generally good to excellent. Most reefs on the low islands are in excellent condition, with the primary human impacts from fishing and ship groundings. There are no problems in the atolls from sedimentation and erosion or coastal pollution. Reefs in Kosrae have been damaged by coastal development, specifically the construction of the airport on top of a reef. Some dredging and road construction projects have also damaged specific reef areas. The reefs around the Pohnpei vary in condition e.g. following a ship grounding near the Sokehs channel, coral cover was about 20%, and estimates on the barrier reef are of 50% to 70% cover at selected sites. Due to the large annual rainfall, and steep volcanic topography, erosion and sedimentation rates are high, and upland clearing of forests to grow sakau (cava) has resulted in landslides and impacts downstream. The high coral cover in Chuuk indicates generally good water quality, however there is over-fishing by foreign commercial operators, including destructive fishing practices, which are causing localised damage. Surveys of 18 sites around Yap in 1995 and 1997 showed coral cover was similar (28.8% vs 28.7%) even though a typhoon hit the island between the surveys. Guam The condition of the reefs is variable, ranging from excellent to poor, depending on adjacent land-use, accessibility, location of ocean outfalls and river discharges, recreational 202
Status of Coral Reefs of American Samoa and Micronesia pressure and water circulation patterns. The northern reefs are generally in better condition because there is limited erosion and sedimentation from the limestone land mass (no surface rivers or streams), but there is some aquifer discharge and associated eutrophication damage to the reefs. Coral cover and diversity are higher on the northeastern (windward) exposures, with a variety of Acropora species dominating the reef crest and slope. Reefs on the eastern, central and southern parts are heavily influenced by clay sediments and freshwater runoff during the rainy season (June to November) with these sediments often accumulating on the reef flats and portions of the reef slope. During the early 1990s, a road project in the south resulted in particularly heavy sedimentation on the fringing reefs, with up to 100% mortality of corals. Most of the fringing reefs off the south and southwest shores are in poor to fair condition. Apra Harbour in the central-west is home to a US Navy Base and the commercial port for the island. The fringing and patch reefs near the harbour mouth are in relatively good condition, whereas those within the harbour have been affected by freshwater runoff, sediment and thermal discharges from the main power generation facilities. Agana Bay and Tumon Bay, north of Apra Harbour, are centres of tourism and recreation activities, with major jet ski operations in Agana Bay. Corals in the inner areas of both bays are in relatively poor condition, influenced by discharges from land as well as the impacts of recreational activities. Improvements in sewerage lines, ocean outfalls and control of runoff are expected to improve water quality in these bays, and some subsequent experimental restoration activities are planned. Coral cover on the good reefs ranges from 35-70%, while the most damaged sites have less than 10% cover, with fleshy algae and sediment dominating. Data compiled in the 1960s generally showed reefs with over 50% live coral cover, but only 7 of the same 113 transects measured in the 1980s - 1990s had over 50% live coral cover, while 88 had less than 25% live coral. Near the Northern District sewer outfall in the early 1990s, coral cover was below 25%, moreover there were very few species, particularly Porites rus, indicating a reduction in coral species diversity. Recruitment data also support the observations of an overall decline in coral reef condition. In 1979, 278 coral recruits were found from 525 fouling plates placed on reefs around Guam (0.53 corals/plate), while in 1989 and 1992 there were only 0.004 and 0.009 recruits per plate respectively. Recent increases in blue-green algae are resulting in overgrowth of corals at some sites. While the crown-of-thorns starfish (Acanthaster plancii) occurred in small to moderate numbers over the past few years, many juveniles now are causing concern about the potential for a future outbreak. Coral diseases, the competitive sponge Terpios, and coralline algal lethal orange disease (CLOD) have all been observed on Guam’s reefs, but none are causing significant damage. Sporadic episodes of coral bleaching have occurred at a number of sites including within Apra Harbor and Piti Bay just to the north, and both hard and soft corals were affected, with a few pockets of high mortality, however, the 1998 mass bleaching did not cause widespread coral mortality in Guam. Palau Palau has the most diverse coral fauna in Micronesia; comparable to the highest coral diversity areas of the Philippines, Indonesia and Australia, with 425 coral species. The reefs are generally in good condition with coral cover ranging from 50-70% and sites containing 203
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FOREWORD Over the past few years, I
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CONTENTS COUNTRIES, STATES AND TERR
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COUNTRIES, STATES AND TERRITORIES A
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Countries, States and Territories T
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EXECUTIVE SUMMARY CLIVE WILKINSON T
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Executive Summary CORAL BLEACHING I
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Executive Summary South Asia Most r
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Executive Summary parts of Fiji and
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Executive Summary management and mo
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Executive Summary tourism developme
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Executive Summary problem is loomin
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6. STATUS OF CORAL REEFS IN SOUTH A
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Status of Coral Reefs in South Asia
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8. STATUS OF CORAL REEFS OF EAST AN
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Status of Coral Reefs of East and N
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9. STATUS OF CORAL REEFS OF AUSTRAL
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Status of Coral Reefs of Australasi
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15. STATUS OF CORAL REEFS IN THE NO
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Status of Coral Reefs in the Northe
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17. STATUS OF CORAL REEFS IN THE EA
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Status of Coral Reefs in the Easter
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18. STATUS OF CORAL REEFS IN SOUTHE
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Status of Coral Reefs in Southern T
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19. SPONSORING ORGANISATIONS, CORAL
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Sponsoring Organisations, Coral Ree
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LIST OF ACRONYMS AGRRA AIMS ASEAN B
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Status of Coral Reefs of the World 2000

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