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1 . Marshall Islands     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. The isolated atolls of Enewetak and Ujelang lie to the west of these main chains. Wake atoll, to the north, is clearly linked to this group biologically and geologically, but is separately administered by the USA (see Chapter 14). In all there are some 1 136 islands dispersed over a vast area of ocean, although the total land area is very small. The atolls are typically circular to elliptical with shallow lagoons. Kwajalein, at some 2 500 square kilometers, is the largest atoll in the Pacific. The two chains were probably formed by plate movement over a volcanic hotspot, although there is no current volcanic activity. Deep drilling into the reefs of Bikini and Enewetak atolls revealed a sequence of reef deposits ranging from 1.3 to 1.4 kilometers thick overlying basalt rock from the original volcanic activity. Dating work on the fossils at the base of these, together with the youngest basalt rock below, indicated that this volcanic activity occurred 50-59 million years ago. All of the islands lie close to sea level with a mean height of about 2 meters.

Politically the Marshall Islands form an 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. There has been some breakdown of traditional landuse and cultural systems, exacerbated by the considerable movements forced during the nuclear testing (see below). However, artisanal fishing remains very important, and is now being more widely encouraged. Commercial fishing is largely restricted to foreign-licensed tuna vessels, but there is also an aquarium fishery which has been operating out of Majuro for about 20 years, largely exporting to Hawaii. Some high value species are also being exploited, including trochus, giant clams and marine turtles. Shark fins are obtained as by-catch from the tuna fisheries. There is also a limited amount of aquaculture development, focussed on clams (for the aquarium trade), pearl oysters and trochus. Sealevel rise associated with climate change is a particular threat to these low-lying islands.

Perhaps the best known “use” of the atolls of the Marshall Islands was nuclear weapons testing by the USA in the 1940s and 1950s, when some 67 nuclear detonations were performed on Bikini and Enewetak atolls. These tests were carried out on land, in the air near ground level or over the water. The largest test, the Bravo hydrogen bomb at Bikini, measured 15 megatons (1 000 times the strength of the Hiroshima bomb): fallout from this explosion was carried to the inhabited atolls of Rongelap, Ailinginae, Rongerik, Utrik and others. A study carried out in 1994 confirmed that some 15 atolls and islands were subject to some radioactive fallout during the 1950s, although most of them are now considered clear. The detailed impacts of these tests on the coral reef environment are still unknown, although there were obviously significant physical affects in the areas of direct impact, while a number of large ships were also sunk in the atoll lagoons. Since the 1960s human pressures on these evacuated atolls (Bikini, Enewetak and Rongelap have been repopulated and re-evacuated on different occasions up to the present day) has been minimal. One positive result of this has been significant increases in some fish groups, including predators such as sharks and jacks (Carangidae) on the surrounding reefs. It may be that these are among the most “pristine” coral reef communities in the region. The USA maintains a military presence in these islands and continues to operate the Kwajalein Missile Range on Kwajalein Atoll.
Source: Spalding, M.D., C. Ravilious and E.P. Green , 2001 , World Atlas of Coral Reefs . Prepared at the UNEP World Conservation Monitoring Centre. University of California Press,Berkeley,USA.421p. (See Document)

2 . Marshall Islands     Marshall Islands
INTRODUCTION AND SETTING
The reefs of the Marshall Islands are among the most pristine in the Indo-Pacific, having suffered minimal damage from bleaching, destructive fishing techniques, and sedimentation. However, signs of unsustainable resource exploitation are apparent, including the earlier extirpation of the largest giant clams, and the ongoing reduction of reef shark, grouper, and Napoleon wrasse populations. In addition, localized outbreaks of crownof-thorns starfish (COTS) and coral disease, principally on the capital atoll of Majuro, are ongoing. Another concern is the growing, unregulated exploitation of reef fish for the local markets.

The Republic of the Marshall Islands (RMI) encompasses approximately 1,225 individual islands and islets with 29 atolls and five solitary low coral islands (Figure 13.1). Land makes up less than 0.01% of the area of the Marshall Islands, with a total dry land area of approximately 181.3 km2 . Most of the country is open ocean with a seafloor that reaches 4.6 km deep. Including the Exclusive Economic Zone (EEZ; shoreline to 200 miles offshore), the RMI covers 1,942,000 km2 of ocean within the larger Micronesian region. Furthermore, there are 11,670 km2 of semi-enclosed water within the lagoons of the atolls.

Scattered throughout the country are nearly one hundred isolated submerged volcanic seamounts. Seamounts with flattened tops, or guyots, are thought to have formed millions of years ago but were unable to keep pace with subsidence or persist as islands or atolls.

The average elevation of the Marshall Islands is about 2 m above sea level. Humidity is around 80% with considerable salt spray. The air temperature averages 27.8ºC with an annual range of 24-32ºC. Rainfall tends to be seasonal, ranging from 4 m a year in the south to as little as 0.6 m a year in the north. In extremely dry years, there may be no precipitation on some atolls. Tropical storms (typhoons) are relatively rare, but can be devastating when they occur.

The atolls vary in size from Kwajalein, the world’s largest atoll with 16.4 km2 of dry land and a lagoon of 2,174 km2 , to Bikar with 0.5 km2 of land and 37.4 km2 of lagoon, and Namdrik with 2.7 km2 of land and 8.4 km2 of lagoon. Individual islands range from tiny sand-spits and vegetated islets that are inundated during storms and extreme high tides to much larger islands such as Kaben Island at Maloelap Atoll, and Wotho Island, the main island at Wotho Atoll, both of which are over 8 km2 . Lagoons within the atolls typically have at least one deep-pass access; however, some, such as Namdrik Atoll, have no natural passes.

The atolls and islands of the Marshalls formed when fringing reefs began to establish and grow around emergent volcanoes. The ancient volcanic peaks then gradually sank and shrank, while fringing reefs continued to grow, eventually becoming coral atolls after the volcanoes disappeared entirely beneath the sea. The five solitary islands of the RMI were formed in much the same way, but the peaks were small enough that no interior lagoon developed.

For the most part, the atolls of the Marshalls are not circular, nor do they have uniform islets. They are much larger than those in the Indian Ocean and are surrounded by more numerous islets. The islets are more prevalent on the windward side and encircle a deep lagoon. The lagoons of RMI atolls also differ from others in that they are typically deeper (to about 60 m) and have greater circulation.

The islets are extremely young geologically and likely formed when sea level dropped about 2 m to its present level around 4,000 years ago, with more recent land creation resulting from the action of large waves which cast large reef blocks, coral rubble, and sand on top of shallow reefs. Vegetation, birds, crabs, and other animals then colonized the emergent islands, and eventually the Micronesian ancestors of the present day Marshall Islanders arrived on sailing canoes. In contrast, the atoll reefs are 50 million years old or more, and up to 1.5 km thick atop their volcanic foundation.
Source: Silvia Pinca, Maria Beger, Dean Jacobson, Terry Keju , 2005 , The State of Coral Reef Ecosystems of the Marshall Islands . pp. 373-386. In: J. Waddell (ed.), The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2005. NOAA Technical Memorandum NOS NCCOS 11. NOAA/NCCOS Center for Coastal Monitoring and Assessment’s Biogeography Team. Silver Spring, MD. 522 pp. (See Document)

3 . Marshall Islands     Marshall Islands
In general, the reefs of the Marshall Islands are in good condition. While the two atolls used for the nuclear testing program have experienced unique stresses, the reefs of the RMI as a whole have escaped the extensive damage seen in other parts of the world. Reefs surveyed at various locations in 2001, 2002, and 2003 were found to be in a very healthy condition, with a large number of fish, healthy corals, and algae. One could argue that because no humans inhabit atolls affected directly or indirectly by nuclear testing, the reefs at these atolls have recovered to support seemingly natural equilibrium populations that largely remain unexploited to date. Abundant megafauna such as sea turtles, whales, rays, and Napoleon wrasses were also recorded.
Source: Silvia Pinca, Maria Beger, Dean Jacobson, Terry Keju , 2005 , The State of Coral Reef Ecosystems of the Marshall Islands . pp. 373-386. In: J. Waddell (ed.), The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2005. NOAA Technical Memorandum NOS NCCOS 11. NOAA/NCCOS Center for Coastal Monitoring and Assessment’s Biogeography Team. Silver Spring, MD. 522 pp. (See Document)

4 . Marshall Islands     Marshall Islands
The Marshall Islands are comprised of 29 atolls and 5 low reef islands grouped into two north-south oriented chains. There are nearly 300 coral and more than 800 fish species, and most reefs are virtually pristine with very high coral cover (50-90%) and relatively high algal cover. The country has been relatively unaffected by over-fishing, destructive fishing, coral bleaching, sedimentation, coral disease, and COTS outbreaks, although remote atolls are targeted for shark finning. The highly populated atoll of Majuro has suffered rapid, profound degradation and high fishing pressure leading to reductions in fish communities and declines in coral diversity. The RMI has one of the few remaining healthy populations of humphead wrasse (p. 52) and predominantly healthy shark populations. Some outer atolls are considered very healthy and pristine with abundant megafauna despite no take zones being only recently initiated. Ailinginae Atoll and Bikini Atoll will be nominated for World Heritage status in early 2009.
Source: Goldberg, J., K. Adams, J. Albert, J. Asher, P. Brown, V. Brown, D. Burdick, B. Carroll, P. Craig, D. Fenner, C. Fillmed, V. Fread, M. Gawel, A. George, Y. Golbuu, L. Goldman, C. Graham, A. Hall, M. Hasurmai, L. Jacob, D. Jacobson, E. Joseph, J. Kenyon, W. Kostka, T. Leberer, M. Luckymis, E. Lundblad, S. Malakai, J. Maragos, A. Marcus, S. Marino, D. Mathias, J. Mcilwain, J. Miller, D. Minton, M. Nadon, S. Palik, N. Pioppi, L. Raymundo, B. Richards, M. Sabater, R. Schroeder, P. Schupp, E. Smith, T. Zgliczynski and B. Zgliczynski , 2008 , Status of Coral Reef Resources in Micronesia and American Samoa: 2008 . In: Wilkinson, C. (ed.). Status of Coral Reefs of the World: 2008. Global Coral Reef Monitoring Network and Reef and Rainforest Research Center, Townsville, Australia. p199-212. (See Document)

5 . Marshall Islands     Marshall Islands
Located in the central Pacific Ocean and spanning more than 5,025,000 km2 (1,940,000 mi2), the Republic of the Marshall Islands (RMI) is comprised of 1,225 islands and islets including 29 atolls and five solitary, low coral islands. Only 0.01%, or 181.3 km2, of the country is dry land. The atolls and islands are arranged in two roughly parallel groupings—the eastern Ratak (or Sunrise) Chain containing 15 atolls and two islands, and the Ralik (Sunset) Chain to the west containing 14 atolls and three islands (Figure 12.1).



The RMI formed when fringing reefs began to establish and grow around emergent volcanoes. While the ancient volcanic peaks gradually sank and shrank, the fringing reefs continued to grow and eventually coral atolls formed after the volcanoes disappeared entirely beneath the sea. The five solitary islands of the RMI were formed in much the same way, but the peaks were small enough that no interior lagoon developed. Most atolls of the Marshall Islands consist of an irregular shaped reef-rim with numerous islets encircling a lagoon with water depths that can reach 60 m. The islets are more prevalent on the windward side. The atolls vary in size from Kwajalein, the world’s largest atoll with 16.4 km2 of dry land and a lagoon of 2,174 km2, to Bikar with 0.5 km2 of land and 37.4 km2 of lagoon, and Namdrik with 2.7 km2 of land and 8.4 km2 of lagoon. Individual islands range from tiny sand-spits and vegetated islets that are inundated during storms and extreme high tides to much larger islands such as Kaben Island at Maloelap Atoll, and Wotho Island at Wotho Atoll, both of which are over 8 km2. Lagoons within the atolls typically have at least one natural reef pass that provides boat access; however, some, such as Namdrik Atoll, have no natural passes.



Prior to Western contact, the people of the Marshall Islands relied on fishing and tropical agriculture for subsistence. In this environment, the Marshallese developed world-renowned seafaring skills, which included the design of ocean-going canoes and the creation of a complex navigation system based on stars, swell, currents and wave refraction patterns. The culture and skills that evolved allowed the Marshallese to thrive in the widely dispersed islands. The present population of approximately 61,815 is concentrated in the urban areas of Majuro and Ebeye (Kwajalein Atoll), home to approximately two-thirds of the population (CIA, 2008). The remaining one-third lives in the more remote atolls, commonly known as the "outer islands".
Source: Beger, M., D. Jacobson, S. Pinca, Z. Richards, D. Hess, F. Harriss, C. Page, E. Peterson and N. Baker , 2008 , The State of Coral Reef Ecosystems of the Republic of the Marshall Islands. pp. 387-418 . In: J.E. Waddell and A.M. Clarke (eds.), The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2008. NOAA Technical Memorandum NOS NCCOS 73. NOAA/NCCOS Center for Coastal Monitoring and Assessment's Biogeography Team. Silver Spring, MD. 569 pp. (See Document)

6 . Marshall Islands     Marshall Islands
Natural Resources Assessment Surveys (NRAS)



Given the realities of population growth and the potential for resource exploitation throughout the RMI, it is important to collect as much baseline data on the surrounding coral reef habitats as possible. NRAS-Conservation, a local NGO, along with the CMI and MIMRA began such efforts to document the status of RMI reefs. NRAS expeditions comprising a team of 9-10 international and local Marshallese scientists surveyed reef habitats at Likiep (2001), Bikini (2002), Rongelap (2002-2003), Mili (2003), Namu (2004), Majuro (2004) and Ailuk (2006). The NRAS surveys include baseline data on fish, sharks, corals, invertebrates and marine algae. Summary information is available at: www. nras-conservation.org /. NRAS rapid ecological assessments (REAs) are intended to serve as baseline data for managers and scientists to aid in the establishment of Marine Protected Areas.



Methods

The NRAS survey methods provide data on benthic composition and coral community structure along a series of four transects located at predetermined depths (Table 12.2). Coral and substrate data are collected by a diver swimming along each 50 m tape and recording the type of substrate (e.g., bedrock, rubble, sand, dead and live coral, seaweeds and coralline algae) below the tape at 50 cm intervals (English et al., 1997; Pinca, 2005). This line-intercept method of assessment was selected to best characterize the area as a whole, taking into account the range of depth and zones present (Pinca, 2005).



Data on fish, invertebrates and macroalgae were also collected along four 50 m transects located at predetermined depths. More detailed fish and invertebrate survey methods are summarized in the Associated Biological Communities section. Data on the abundance and composition of macroalgae were collected by placing a 25 x 25 cm quadrat next to the transect line at 0, 10, 20, 30 and 40 m. Target genera and larger groups were identified, and percent coverage of each was approximated inside the quadrant and averaged for each depth. Abundance estimates were recorded according to a qualitative scale of rare, abundant and dominant.Coral species richness was surveyed during 60 minute timed swims at each survey site. This method involves an initial direct descent to 30 m, followed by a slow, zigzag ascent to shallow parts of a reef (Beger and Pinca, 2003). Coral species were given an abundance rating according to the DAFOR scale (relative abundance scale: dominate, abundant, frequent, occasional, or rare). Overall percent cover of live coral was estimated for each site, and the three most dominant coral species were recorded (Beger and Pinca, 2003). The results of the surveys are reported in the order in which they were conducted.
Source: Beger, M., D. Jacobson, S. Pinca, Z. Richards, D. Hess, F. Harriss, C. Page, E. Peterson and N. Baker , 2008 , The State of Coral Reef Ecosystems of the Republic of the Marshall Islands. pp. 387-418 . In: J.E. Waddell and A.M. Clarke (eds.), The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2008. NOAA Technical Memorandum NOS NCCOS 73. NOAA/NCCOS Center for Coastal Monitoring and Assessment's Biogeography Team. Silver Spring, MD. 569 pp. (See Document)

7 . Marshall Islands     Marshall Islands
NRAS Bikini Atoll Assessment (2002)



Bikini Atoll is one of the most northerly atolls and includes 23 islands and 187 km2 of reef. Reef habitats at Bikini atoll include narrow fringing reef with spur and groove development, reef crest and steep vertical exposed walls, and protected sandy lagoons with patch reef development and inter-reefal fauna (Pinca and Beger, 2002). A total of 183 species of scleractinian coral were recorded from 19 sites at Bikini Atoll in 2002 (Richards et al., in press). Table 12.3 details live coral cover at six biogeographic zones.



As described in detail by Richards et al., in press, this atoll has been subject to considerable exposure to radioactive nuclear material. Between 1946 and 1958, 23 tests were conducted at seven test sites located on the reef, at the water surface in deep and shallow areas, in the air and underwater for a combined explosive yield of 76.3 megatons. These tests resulted in the creation of five craters up to 73 m deep (Noshkin et al., 1997b) and alteration of natural sediment movement patterns (Noshkin et al., 1997a). The most highly publicized of the Bikini tests, nicknamed "Bravo", involved the detonation of a 15 megaton hydrogen bomb on a shallow fringing reef in 1954 (Niedenthal, 2001). It obliterated three islands and sent millions of tons of sand, coral, plant and sea life from Bikini’s reef into the atmosphere. The Bikini lagoon sediment regime was fundamentally altered by the nuclear events due to the pulverization and subsequent resuspension of millions of tons of sediment that are transported and deposited throughout the lagoon to this day. Since the nuclear testing, impacts from pollution and tourism are presumed to have been virtually non-existent in RMI’s uninhabited northern atolls, however, the threat of illegal fishing persists.
Source: Beger, M., D. Jacobson, S. Pinca, Z. Richards, D. Hess, F. Harriss, C. Page, E. Peterson and N. Baker , 2008 , The State of Coral Reef Ecosystems of the Republic of the Marshall Islands. pp. 387-418 . In: J.E. Waddell and A.M. Clarke (eds.), The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2008. NOAA Technical Memorandum NOS NCCOS 73. NOAA/NCCOS Center for Coastal Monitoring and Assessment's Biogeography Team. Silver Spring, MD. 569 pp. (See Document)

8 . Marshall Islands     Marshall Islands
NRAS Mili Atoll Assessment (2003)



Mili Atoll is one of the most southern atolls in the Ratak Chain and supports a population of more than 800 people spread among 92 islands comprising 16 km2 (6.15 mi2) of land. In June and July of 2003, REAs were conducted at 20 sites around Mili. The surveys were requested by local landowners and political leaders to support their efforts to establish a marine sanctuary and research station in the northeastern portion of the atoll (Beger and Pinca, 2003). With the assistance of CMI, NRAS baseline data was collected to help determine the optimal location for a marine reserve. These data will also provide a basis for future monitoring programs and facilitate comparisons with reefs in other parts of the country and region.



A total of 20 sites were sampled during a two week period; nine dive sites were located on the ocean side of the atoll, one dive site was located in the South Pass and nine sites were surveyed in the lagoon and pinnacles (Beger and Pinca, 2003). The survey sites were selected to be representative of subregions (habitat areas) that experience environmental variation related to geographical location and degree of exposure to wind and waves (Beger and Pinca, 2003). These regions are: north ocean, west ocean, south ocean, south pass, south pinnacles and north lagoon areas.



Mili’s reefs were found to be in excellent condition, with an abundance of fish, coral, algae and other species. The monitoring sites with the highest coral cover were located at two west lagoon sites (53 and 57%). Both sites were located on the leeward side with respect the prevalent winds. High coral cover was also found at sites in the north, west and southern ocean regions. Remaining regions showed a high proportion of sand (Beger and Pinca, 2003. The lowest coral cover was recorded on the leeward ocean side (north of the atoll). Non-Acroporid branching corals were represented with the highest relative coverage in the lagoon, as well as the pinnacle areas whereas Non-acroporid encrusting corals dominated the ocean sites (Beger and Pinca, 2003). Overall, the most frequently occurring coral was Isopora palifera/cuneata. Coral cover for six biogeographic zones is listed in Table 12.4.



The number of coral species present at each site ranged from 44 to 72 with an average of 50 corals (±10.3; Beger and Pinca, 2003). Lagoon areas tended to support a higher number of corals, as well as many unique species. Additionally, northern ocean areas supported a high number of corals, while in southern ocean sites fewer coral species were documented (Beger and Pinca, 2003). Lagoon and ocean sites proved to be the most diverse.



No sign of coral bleaching was recorded for the atoll of Mili. No coral diseases have been recorded and only four COTS were found. No anthropogenic impacts were recorded in Mili.



The lowest (14%) cover in fleshy seaweeds was found at the western ocean sites as well, where the highest cover of coralline algae was recorded.
Source: Beger, M., D. Jacobson, S. Pinca, Z. Richards, D. Hess, F. Harriss, C. Page, E. Peterson and N. Baker , 2008 , The State of Coral Reef Ecosystems of the Republic of the Marshall Islands. pp. 387-418 . In: J.E. Waddell and A.M. Clarke (eds.), The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2008. NOAA Technical Memorandum NOS NCCOS 73. NOAA/NCCOS Center for Coastal Monitoring and Assessment's Biogeography Team. Silver Spring, MD. 569 pp. (See Document)

9 . Marshall Islands     Marshall Islands
NRAS Namu Atoll Assessment (2004)



Namu atoll is made up of 54 islets located in the west Ralik chain and is home to approximately 800 people, distributed primarily among the main islands of Namu, Majikin, Mae, Loen. In December 2004, 21 sites were surveyed as part of a NRAS assessment: eight sites were located within the lagoon, two were at passes and 11 were on the ocean side. The eastern and northern sides of Namu were not surveyed for logistical reasons. Sites were grouped into five zones according to their location and general characteristics of topography and substrate. These included sites located in the northern part of the lagoon, two pinnacles surveyed in the northern part of the lagoon, fore reef sites of the western side of Namu, the fore reef area at the very south of the atoll around Len island and sites at the two passes, one in the north (Bok passage) and one to the southwest (Anil passage).



Namu Atoll is peculiar because of the narrow shape of its lagoon and the presence of passes only on the west site which
makes the lagoon a relatively closed environment with little circulation. The biological characteristics of this atoll are:
-A very high abundance of alga Microdyction in the lagoon and north-western ocean walls
-High abundance of fish and sharks, (which were found in deeper water than at other atolls)
A high presence of Stylasteridae on the ocean walls
-A high concentration of Heliopora coerulea and Isopora sp. in the upper reef and reef flat of the ocean side
Presence of Millepora of peculiar shape in high columns both off the walls as well as on pinnacles and
-A high abundance of very large sea fans (Melithaea) in the passes.



Total relative cover of live coral was highest at the south fore reef of Namu (Ocean South) and ocean west (Ocean West) sites (Table 12.5). The two passes showed higher cover of corals than lagoon sites, which were particularly low in coral. Here most of the coral surface was covered by algae, especially Microdyction. Along the reef, the abundance of live corals decreased with depth from an average of 33% to 24% while the relative abundance of algae increased from 28 to 37 %. In the lagoon, the few sloping patches of corals near the islands supported fewer coral species and several had small patches of white tissue, probably resulting from COTS predation. A large area of bedrock was also found to be densely covered by the alga Microdyction as well as many sponges, primarily chandeliers sponges of the genus Callyspongia.



The few lagoon pinnacles at Namu host some large massive corals (Lobophyllia sp.) in deep water, many colonies of Seriatopora hystrix and Stylophora pistillata and small massive Porites sp. In shallow water, the diversity of corals is much higher and includes large colonies of massive Porites, Caphophillia, and the soft coral Rumphella, but also bare rock. Namu supports a high abundance of Millepora, which forms high columns and complicated structures, as well as Isopora, large blue coral (Heliopora coerulea), Astreopora, massive Porites, Pavona, Faviids and many Stylasteridae. The two sites at the north pass (Bok passage) and at Anil passage in the south, were similar in appearance: both contained numerous shallow Isopora and Heliopora coerulea colonies with a dominance of massive Porites at deeper layers. Soft corals are abundant in both channels with small white Dendronephtya and Ruphella, and many small and large sea fans (Gorgonians Melithaea sp.) and Lobophyton all along the profile between 15 and 30 m, there are spectacular large gardens of Melithea and Junceella interspersed with giant sponges (Xestospongia).



The wall to the west side of Namu atoll is very rich in corals, and its appearance does not change much from north to south. Rock encrusted with Lithothamnion (a coralline alga) dominates the reef crest and upper reef of the northern sites, along with abundant Isopora, Millepora and the highest diversity of corals. Blue coral (H. coerulea) are abundant at the upper slope and crest, as well as inside the deep gullies where they compete for space with species of Stylasteridae.



The slope is densely colonized by Porites at 15-20 m, with large valleys or gullies and massive coral colonies, giving a complicated topography to the reef. The deep spurs and grooves, usually found on the windward side of atolls, are common on this leeward side in Namu. The wall is fairly steep and below 20 m only rare corals are found. Abundant Lobophyton is found around 15-20 m and Rumpella sp. can be found below 25 m. The wall becomes more vertical at 30-35 m with large Melithea and some foliose corals. In the southern outer reef, the coral cover is dominated in the shallow reef flat (5-10 m) by Acropora, Isopora and coralline algae (Goniastrea, massive Hydnophora, Turbinaria, large colonies of Pocillopora damicornis, Stylasterina, H. coerulea). At 12-14 m, the reef is composed of many Acropora spp., small Pocillopora and lots of coralline algae. The upper reef slope is dominated by very large massive colonies of Porites and H. coerulea. The wall starts at 18-20 m and deeper parts of the wall are sparsely colonized by rare corals and small colonies of massive Porites.
Source: Beger, M., D. Jacobson, S. Pinca, Z. Richards, D. Hess, F. Harriss, C. Page, E. Peterson and N. Baker , 2008 , The State of Coral Reef Ecosystems of the Republic of the Marshall Islands. pp. 387-418 . In: J.E. Waddell and A.M. Clarke (eds.), The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2008. NOAA Technical Memorandum NOS NCCOS 73. NOAA/NCCOS Center for Coastal Monitoring and Assessment's Biogeography Team. Silver Spring, MD. 569 pp. (See Document)

10 . Marshall Islands     Marshall Islands
NRAS Majuro Atoll Assessment (2004)



Home to nearly half of RMI’s population, Majuro Atoll is the political and economic capital of RMI and is situated in the southern portion of the Ratak Chain. The coral reefs surrounding this heavily populated atoll suffer impacts from environmental and anthropogenic stressors like marine debris, terrestrial runoff, pollution and overexploitation more than reefs of the outer islands.



In 2004, 16 sites around Majuro atoll were surveyed according to standard NRAS survey protocols. Notwithstanding the high population (20,000 people), numerous construction and development activities, and the presence of more than 5,000 cars, Majuro atoll still contains healthy and diverse coral reefs at some sites. The most impacted parts of the atoll are the nearshore lagoon adjacent to the downtown area, called DUD (Darrit, Uliga, Delap) and sections of the southern coast, where heavy dredging has removed reef structure, increased siltation and sedimentation, changed water circulation patterns, and increased erosion. However, survey sites on the ocean side of the atoll generally contained high live coral cover and relatively high coral species diversity.



The sites with the highest coral cover included one site on a central pinnacle (where Porites rus formed enormous monospecific stands) and the fore reef sites on the east and north sides of Majuro atoll (Table 12.6). The highest abundance of dead coral was found at the southeast lagoon site near the airport. This area has degraded rapidly in the past 4-5 years due to shallow bleaching of the reef flat in the years 2002 and 2003, dredging associated with the construction of an airport hangar and other coral mining activities. Coral diversity and cover declined and the abundance of fish diminished over these few years (S. Pinca, pers. obs.). Dredging continues to occur at the present time. The substrate composition changes with increasing depth along the shelf. Live coral becomes rare with depth while sand, bedrock and algae increase in abundance. Areas of high live coral cover and species richness are located on the reef flat and reef crest.



Overall coral diversity on Majuro is low, with many sites having only six genera represented by less than 20 species. Porites rus is one of the most common corals found in the area. P. rus, which is rare or absent on a number of remote atolls, is dramatically increasing its dominance on Majuro, particularly since it thrives in disturbed environments. This assertion is also supported by distribution patterns seen at Arno atoll. Along the western shoreline, where conditions are good, P. rus only grows in the blast-disturbed anchorage near the fishing jetty.



In many lagoon sites, non-Acropora corals (especially three species of Porites) prevail over Acropora corals, except in some parts of the outer reefs where branching and table Acropora and Isopora cuneata/palifera colonies are present in high numbers and constitute more than half of the coral population (Figure 12.16). The large Acropora tables account for less cover in the lagoon and at pinnacle sites. Acropora were found to become less abundant as depth increased, a trend not observed for non-Acropora corals.



No sign of coral bleaching was recorded during surveys in 2005. However, several COTS were recorded at the eastern part of the lagoon, and corals observed there were brittle and often covered in Dictyota. Although P. rus was the dominant species, several pockets of high species richness were found inside the lagoon and at some outer slope sites. These pockets supported abundant and healthy populations of Pocillopora sp. (in the southern lagoon area and near the airport parking lot), Seriatopora histrix, Porites cylindrica, Pachyseris speciosa, Goniopora, Montipora and Scaphopyllia.



The reefs of the northwest lagoon are singularly diverse, including large plate and foliose colonies of Echinopora, Echinophyllia, Pachyseris, Pavona and Leptoseris. Smaller massive and encrusting colonies such as Faviids, Goniastrea, Astreopora, Merulina, Scapophyllia, Platygyra, are spectacularly abundant. Large colonies of Lobophyllia are abundant, and species that are relatively rare elsewhere are regularly encountered. At least 24 genera were found in a single 25 m belt transect. The northwest lagoon site is the only known lagoon location where an algae that dominates at outer atolls, Microdictyon, is abundant. Unfortunately, these once-healthy reefs have suffered high levels of COTS predation since 2005 which has resulted in considerable colony mortality.



Sites along the eastern coast from Rita to Delap point were very healthy and rich in both corals and fish, which makes this area popular with sport divers. The reef flat and slope present full coral coverage with very large table Acropora and Pocillopora colonies down to about 15 m. Deeper than 15 m (Figure 12.17), bedrock and dead corals make up the substrate, along with healthy smaller table corals, colonies of Pavona, Montipora, large colonies of Goniopora and some soft corals (e.g., Lobophytum). The northern outer reef outside of Kolal-en pass is a beautiful and healthy area and is known by tourists as "The Riviera". The reef flat near Kolal-en is very wide and drops off gradually along a gentle slope with very high live coral cover until it reaches a drop off at 15-18 m. Only a few live corals are found deeper than 20 m. Many Acropora corals are found in 10-15 m, along with blue coral (H. coerulea), which are replaced at deeper levels by Porites cf. lobata, Astreopora and soft corals (Sinularia).



High macroalgal cover was reported at both ocean and lagoon sites. At Majuro atoll, as well as at most other RMI atolls, the populations of macroalgae seem to be in balance with coral. On the other hand, in lagoon areas, the presence of algae is frequently associated with unhealthy conditions. For instance, Dictyota has a strong presence at northern lagoon sites, particularly Irooj Island, while Lyngbia (filamentous algae) is found in abundance at the southern side (Pinca, 2005). The high presence of these algae may indicate past bleaching events or COTS outbreaks (Pinca, 2005). Among the algae recorded, encrusting coralline algae (Halimeda sp.) and blue green algae (cyanobacteria) are overall the most frequently encountered species. Halimeda is very common on reefs and is found especially on the slopes and walls at ocean sites. The abundance of Microdyction, another very common alga on healthy reefs of RMI, is less at Majuro than at other atolls, where it can cover large areas of substrate both inside and outside the atoll. Microdyction and Halimeda are separate by depth: Microdyction is found at more shallow depths, while Halimeda is deeper. Encrusting coralline algae are found throughout the depth range but are more abundant at shallower depths. Other outer reef algae documented include Peyssonnellia and a few observations of algae in the genus Turbinaria. Other algal genera such as Tydemania and Padina were common at lagoon sites. The pinnacle showed the least average macroalgal cover. Blue sponges of the genera Cribochalina and Ianthella were common in the lagoon.
Source: Beger, M., D. Jacobson, S. Pinca, Z. Richards, D. Hess, F. Harriss, C. Page, E. Peterson and N. Baker , 2008 , The State of Coral Reef Ecosystems of the Republic of the Marshall Islands. pp. 387-418 . In: J.E. Waddell and A.M. Clarke (eds.), The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2008. NOAA Technical Memorandum NOS NCCOS 73. NOAA/NCCOS Center for Coastal Monitoring and Assessment's Biogeography Team. Silver Spring, MD. 569 pp. (See Document)

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