The eastern section of the Pacific,
stretching in an easterly direction from Tonga, and to Hawaii in the
north and French Polynesia in the south, constitutes the area known as
Polynesia. A very large number of islands and reefs are scattered across
this wide region. The westernmost islands of Tonga and Wallis and Futuna
lie on the boundary between the Pacific and Indo-Australian plates, with
considerable ongoing plate-margin volcanic activity in Tonga. The
remainder of the region is located on the Pacific plate, and all of the
other islands can be linked to mid-plate volcanic activity. There are
many island chains that have been produced by the movement of the plate
surface over hotspots, and volcanic activity continues in the Hawaiian
With over 11,000 square kilometers of
coral reefs there is a wide range of reef types harboring highly varied
morphologies and ecological communities. The island arcs provide
excellent examples of atoll development, from volcanic coastlines with
only sporadic coral communities through high islands with fringing
reefs, to partially submerged volcanoes with barrier reefs, and finally
true atolls. In the north and south the Hawaiian and Austral
Archipelagos both provide examples of the latitudinal limits to reef
development, with decreases in both diversity and reef constructions in
the cooler waters away from the tropics. Polynesia also marks the edge
of the Indo-Pacific region. Species diversity is relatively low in
almost all species groups, and there are marked declines in diversity as
one moves eastwards.
In modern times this region has become
an area of contrasts. A number of countries and states remain remote and
isolated with small populations dependent on fisheries. Tourism has
become a very important economic resource for a few countries. In
particular Tonga, French Polynesia and Hawaii. Traditional utilization
and management of reef resources has largely been lost in the more
developed islands, and there are typical problems of overexploitation
and pollution associated with the areas of most intense human
development. In all, however, the extent of such pressures remains
localized, and there are vast areas of reefs in good condition.
Hawaii is largely populated by people of
non-Polynesian origin and traditional uses of coral reefs have almost
completely ceased. Alongside these changes Hawaii has developed the most
extensive network of marine protected areas in the entire Pacific Ocean
Tuvalu is a small archipelago consisting of five
true atolls and four other platform islands with encircling fringing
reefs. There are also other seamounts which may reach within 30 meters
of the surface.
The lagoons are predominately sandy with
some coral heads. The outer slopes are reported to be rich in both coral
cove and diversity. Some 400 fish species have been recorded from
Funafuti. There are small mangrove stands in a few areas.
Wallis and Futuna consists of three main islands: Wallis,
Futuna and Alofi. All are high volcanic islands of volcanic origin.
Wallis has fringing reefs around most of its coastline and is further
completely encircled by a barrier reef, with a number of sand cays on
the reef edge. There is only a small number of deeper channels into the
lagoon proper. Futuna has narrow fringing reefs on all coasts, while the
uninhabited Alofi has only a few such areas.
Fishing is an important activity,
although largely still operating at a subsistence level. However, there
have been records of blast fishing. Fringing reefs around Futuna may
have been impacted by sediment runoff and are reported to be degraded.
There is no significant tourism to the islands, and there are no
formal management regimes or protected areas.
OFFICIAL, SCIENTIFIC &
Tokelau is a small group of three small coral
atolls, each with numerous islands on its rim. The lagoons are shallow
with large numbers of coral outcrops, while the maximum height of the
islands is about 4.5 meters. Tokelau, a territory of New Zealand, is
heavily dependent on financial support for development. Concerns about
degradation of the natural environment from over fishing and sewage
pollution have led to some efforts to improve environmental
management. At the end of the 1990's the overall threats to coral reefs
was very low, although there had been a depletion of a number of species
such as giant clam and trochus.
Samoa is dominated by the two large islands of
Upolu and Savaii with a few very small islands nearby. There are
fringing reefs around most of the island's coastlines. Information about
biodiversity is relatively limited. About 50 species of hard coral have
been listed, although this is likely to be a considerable underestimate.
Studies of marine algae have been more complete, and some 300
species have so far been described. Some 991 fish species have been
recorded in the wider Samoan archipelago, of which at least 890 are
shallow reef-dwelling species. There are small areas of seagrass, and
mangrove communities are well developed at a few locations around Upolu.
The people of Samoa are generally
heavily dependent on the reefs at a subsistence level and for the
domestic market. An estimated 4,600 tons of fish were taken for
subsistence in 1997, while domestic markets probably add a further 75-80
tons of fish, crustaceans and other invertebrates. There has been a
noted reduction in biomass and size of fish in shallower and more
heavily fished areas. As the country develops there are increasing
problems of pollution from sewage and solid waste. Poor land use
practices combined with uncontrolled use of agricultural chemicals are
creating high loads of nutrients, toxic chemicals and sediments, placing
the reefs under increasing levels of stress. Tourism, the fastest
growing sector of the economy, is also causing some problems,
particularly in the development of hotel facilities.
Samoa has only one marine protected
area, although the Tafua Rainforest Reserve contains some coastal areas,
and there are plans to develop others. There are also increasing efforts
to involve village participants in conservation awareness. Traditional
marine tenure is recognized, maintaining traditional ownership of
adjacent lagoon and reef fishery resources by the villages.
American Samoa is the eastern portion of the Samoa
Archipelago and consists of five high volcanic islands, and in the east,
Rose Atoll. These islands are surrounded by fringing reefs, with reef
flats typically 50-500 meters wide terminating in a reef slope which
drops sharply for 3-6 meters and then descends gradually down to a depth
of about 40 meters.
Biodiversity is similar to Samoa's,
with 890 species of reef fish recorded around the entire archipelago.
Some 200 coral species have been recorded. There are also small areas of
mangrove on the islands of Tutuila and Aunuu, and the reef rim of Rose
Atoll is dominated by coralline algae. It has an important green turtle
nesting colony, and having been cleared of rats is also a thriving
The vast majority of the rapidly growing
population of American Samoa lives on the southern shores of Tutuila.
Over fishing is a problem on this island, and there are further problems
arising from land-derived sediments and pollutants. Although there is
sewage treatment in the main population centers there are still some
nutrients inputs from sewage in these areas and elsewhere. There are two
tuna canneries which used to add considerable amounts of nutrients to
Pago Pago harbor. These inputs have now been substantially reduced with
the construction of a treated waste disposal pipe further offshore, and
the dumping of high nutrient waste at some 8 kilometers distance. The
coastline on Tutuila has been heavily impacted by road building and
construction and nesting turtles have largely stopped using this area. A
number of reefs and related habitats have been declared as protected
OFFICIAL, SCIENTIFIC &
Fagatele Bay National Marine Sanctuary
National Park of American Samoa
Rose Atoll National Wildlife Refuge
Sensation: The Coral Reefs of Samoa
stretch for over 800 kilometers from north to south, and consist of both
relatively low-lying limestone islands and high volcanic ones. To their
east is the Tonga Trench, which at nearly 11,000 meters is one of the
deepest points in the ocean. Tectonic activity in the country is
considerable and many islands and shoals in the west are too
volcanically active at the present time for reef development. In the
eastern part of Tonga however, reefs are widespread and well developed.
There are fringing reefs surrounding most coasts, while platform and
barrier-type structures are also located in most of the main island
groups. The most extensive area of reefs are in the Hapa'ai group.
Artisanal fisheries are an important
activity in the country. Studies have shown that almost 70 percent of
the catch is made up of reef fish (notably emperors and mullet). Turtle
eggs and meat are still eaten in many areas. There are also several
important commercial fishers, notably an aquarium trade dealing in fish,
coral and live rock together with limited numbers of invertebrates. Over
fishing is a problem in areas of high population density, especially
around Tongatapu. The problems of over fishing have been exacerbated by
a lack of local ownership of reef resources, enabling commercial
collectors to harvest even close to local communities. In addition of
over fishing, certain relatively destructive fishing practices appear to
be degrading reefs.
Eutrophication is a problem in Tongatapu
and Vava'u, arising from both untreated sewage and fertilizer runoff.
Further problems have been noted resulting from the building of
causeways in Ha'apai and Vava'u, while quarrying, construction and sand
mining create problems in some areas.
Tourism is particularly important for
Tonga, with over 30,000 visitors in 1999. A number of protected
areas have been established, largely focused around Tongatapu.
Niue consists of a single uplifted coral atoll,
oval in shape and reaching a maximum height of about 70 meters above sea
level. It is actually one of the largest carbonate islands in the
Pacific. The island is almost surrounded by a narrow platform cut into
the former reef structure and forming a modern reef flat, becoming
discontinuous in the south and east. Few details are known about the
diversity of the reefs, although 243 marine fish have been reported and
there are reported to be over 43 coral genera.
OFFICIAL, SCIENTIFIC &
Official tourism site for Nuie Island
Tonga Scuba Diving Guide
The Cook Islands are a group of 15 islands,
or island groups, scattered across a wide expanse of ocean. Descriptions
typically divide the islands geographically into a northern and southern
group. The northern Cook Islands are a group of five atolls and a
platform island, while the southern islands show a wide range of oceanic
The biodiversity of Cook Island reefs
has not received a great deal of attention, however it is clear that
they lie at some distance from the mega-diverse areas of the Western
Pacific. It is suggested that the diversity and abundance of species is
greatest around the high (volcanic) islands and lowest around the
uplifted islands. The Cook Islands lie east of the natural distribution
of mangroves and none are recorded.
In the Cook Islands, utilization by the
islanders on coral reefs is considerable. In 1996 about 70 percent of
all households undertook at least some form of subsistence fishing,
including both gleaning from reef flats and boat based fishing. Marine
resources are also extensively used in exports, with large black pearl
farms in Maniniki Atoll providing the main source of export income.
Tourism is an important industry for the Cook Islands, which receive
about 100,000 visitors per year. Snorkelling and diving are popular
There are some human impacts on reefs,
particularly associated with urban and agricultural development.
Sedimentation, chemical and nutrient pollution are all potential
threats. Sea-level rise associated with climate change could present
significant problems for a number of low-lying islands and associated
reefs. Although a number of protected areas are listed it is the low
population densities and the remote location of many reefs that
offer the greatest protection.
OFFICIAL, SCIENTIFIC &
JaneResture.com: Cook Islands
Dive Site Directory: Rarotonga, Cook Islands
French Polynesia represents one of the largest territories
in the Pacific and incorporates some 6,000 square kilometers of coral
reefs. It is divided into five distinct archipelagos, each following a
chain oriented from northwest to southeast. Four of these archipelagos
trace the movement of the earth's crust over volcanic hotspots and their
structures are younger in the southeast, where there are a number of
The Marquesas, a group of high volcanic
islands together with a number of smaller islets and shallow banks, form
the northernmost archipelago. They lie in the path of the westward
flowing South Equatorial Current and are climatically quite distinct
from the others islands, with very low rainfall showing a peak in June.
Their northerly latitude places them relatively close to the equator so
they are rarely impacted by cyclones. Despite this, reef development is
poor. There are short stretches of fringing reefs and many less clearly
defined structures. These reefs are very young, and their diversity is
The Tuamotus make up the largest and
geologically the oldest archipelago. They consist of low coralline
atolls, with the exception of Makatea, which is raised, reaching some
113 meters above sea level. These atolls include some of the
largest in the Pacific -Fakarava at 1,400 square kilometers and Rangiroa
at nearly 1,800 square kilometers, with some 240 islands along its atoll
rim. Taiaro Atoll near the center of the group is slightly uplifted,
with a completely enclosed lagoon. The closure of this lagoon is thought
to have been relatively recent, and there are some surviving reef
communities despite their apparent isolation and the raised salinities.
The Society Islands are among the best
known in the region. Mehetia in the southeast is an active volcano with
only sparse coral development along its coastline. Tahiti is the largest
island in the country. Like the neighboring Moorea it is a high volcanic
island with vertiginous slopes. The coastlines of both islands have
discontinuous fringing reefs and are surrounded by offshore barrier
reefs, each broken by numerous passes. To the northwest many of the
islands have similar structures with high central islands and barrier
reefs; however, Maupiti is a near-atoll, and the remaining structures to
the northwest are true atolls.
The Gambier Islands lie at the
southeastern end of Tuamotus, and sometimes considered as part of this
larger group. They represent the eastern extent of French Polynesia. The
main islands are a cluster of four large volcanic islands (Mangareva,
Taravai, Aukena and Akamaru) surrounded by a single barrier reef. These
and other smaller islands in the lagoon show some fringing reef
development. The small atoll of Temoe is sometimes considered part of
the Gambier group.
The Austral Islands lie to the southwest
and include the rock pinnacles of Marotiri (Bass Islands) and the high
volcanic island of Rapa in the far southeast. These are the southernmost
islands of the region, with relatively low sea temperatures. There are
no fringing reefs although there are significant coral communities.
Porites and Pachyseris corals are absent, and algal cover is
high. The remaining islands in the Austral group lie much further north
and have well developed fringing and barrier reefs.
The reefs of French Polynesia include
some of the best studied in the Pacific, but there are nonetheless some
50 islands or atolls which have never been visited by scientists.
Information is particularly limited describing the Gambier, Marquesas
and Austral archipelagos. Located in in the most eastern region of the
Indo-Pacific, diversity is generally relatively low, particularly on a
unit-area basis. Some 168 coral species, about 800 reef fish, 30
echinoderms, 346 species of algae and 1,159 mollusks have been recorded.
There appear to be some general patterns in the dominant species among
different reef types. The lagoons of high volcanic islands are dominated
by Porites, Acopora, Psammocora, and Synaraea, while in
lagoons only Porites and Acropora dominate, and in the
near-closed lagoons only Acropora. Outer slopes largely harbor
Pocillopora, Acorpora and Porites, with coral cover ranging
from 40 to 60 percent at a depth of 15 meters. Even the deeper reef
slopes have high coral cover, with over 90 percent cover in some atolls,
down to 90 meters. There are some distinctive features about the
communities in each of the archipelagos and, although general rates of
endemism are low, there are a number of unique species recorded from the
Marquesas and Gambier archipelagos.
The majority of islands and reefs in
French Polynesia are remote from significant human populations and
remain largely unimpacted by human activities. Fishing is critical for
all of the populated islands, but particularly for those more remote
from urban and tourism developments. One of the major industries in the
country is black pearl culture, which employs around 5,000 people at 600
farms on some 50 islands. This industry supplies about 98 percent of the
world market in black pearls and earns about $130 million per annum.
Tourism is another major industry on
some islands, with 164,000 visitors in 1996. All hotel
developments are coastal, and a
number of hotels extend over the reef
flat on jetties or pontoons. While hotels are required to treat their
wastewater there may be some introduction of nutrient-rich waters into
the lagoons or via the groundwater. Coastal development more generally
has led to considerable modifications of the coastline in Tahiti and
Moorea. Sewage pollution is also a problem close to urban areas in these
two islands, which they also have high levels of sediment runoff,
possibly exacerbated by pesticides and fertilizers, which may have
localized impacts. In Tahiti it has been estimated that 20 percent of
reefs in urban areas have been destroyed, while 75 percent of the
fringing reefs in Bora-Bora, which is one of the most popular tourist
destinations, have been moderately to severely disturbed. Overall,
however, the total extent of these impacts is low or very low compared
to the total area of reefs in French Polynesia.
Only protected areas currently
incorporate coral reefs, making up a tiny portion of the total reef area
in the country. There are ongoing efforts to increase the total area
protected, and to develop community-based management systems for a
number of atoll lagoons.
The Pitcairn Islands are the easternmost islands of the
Indo-Pacific region and consist of a small group of island. Pitcairn
itself is a relatively recent volcanic island reaching some 347 meters
above sea level, around which there are no coral reefs. Other islands in
the group, Henderson, Ducie and Oeno have fringing reefs showing low
biodiversity. The reefs and islands are largely protected by their
isolation, and Henderson Island is a World Heritage Site.
Clipperton Atoll is located in the Eastern Pacific, about
1,100 kilometers southwest of the Mexican part of the American mainland.
It is a roughly circular atoll about 4 kilometers across, with an island
completely encircling its lagoon. There is a 50-200 meter wide reef
terminating in a spur and groove system. The reef slope is relatively
gentle with high coral cover (33-83 percent) in many areas. The deeper
slope has sand and rubble.
This atoll is extremely important in
biogeographic terms. Its easterly location actually places it in a
completely different biogeographic region from other Pacific islands
-the Tropical Eastern Pacific, with close affinities to the reefs and
coral communities of the western coast of the Americas. It is in fact
the best developed reef and the only atoll in the Tropical Eastern
Pacific. Biodiversity is very low, with 18 recorded scleractinian coral
species and 115 fish species. The island is unihabitated and rarely
visited. There is no legal protection of its natural resources.
OFFICIAL, SCIENTIFIC &
NASA's Earth Observatory: Coral Bleaching in
Macgillivray Freeman's Coral Reef Adventure:
Tahiti & Rangiroa
Dive Discovery: Tahiti
Nations Online: French Polynesia
Tahiti Vacation Planners: The Islands of French
The Hawaiian Islands are the most isolated archipelago in the
world, lying considerably north and east of the vast majority of the
Pacific Islands. They were formed as the Pacific tectonic plate moved
northwest over a stationary hotspot beneath the ocean floor. The
youngest island in the group is thus the island of Hawai'i in the
southeast, which shows near continuous volcanic activity. Together with
seven other main islands, it forms a distinct block of high volcanic
islands making up the majority of the land area in the archipelago.
Moving northwest, the older volcanic islands have largely subsided and
there is a long chain of islands and reefs at or near sea level leading
to Kure Atoll in the northwest. These latter reefs lie some distance
north of the tropics. Further north and west of these is the sequence of
Emperor Seamounts extending for thousands of kilometers towards the
Kamchatka coastline of Siberia. These represent former reef-capped
volcanic islands. Their northward migration took them to latitudes where
reef growth was insufficiently rapid to keep up with crustal subsidence,
and then out of the regions of hermatypic coral growth completely.
Fringing reefs are by no means
continuous among the high islands of the southeast, although they are
well developed in a number of places, particularly on leeward (southern
and southwestern) shores. Along the coast of Hawai'i there are no true
fringing reefs, but well developed submerged reefs occur along the
western Kona coast. Recent underwater lava flows provides a substrate
for looking at colonization by reef organisms ins the south and east.
Fringing reefs are better developed in a few locations along the western
shores of Maui, the southern shores of Molokai and the northeastern
shores of Lanai. Oahu has a number of well developed reefs, including a
well studied fringing reef in Hanauma Bay and one of the only barrier
reefs in Kanohoe Bay, which protects a large number of patch reefs and a
coastal fringing reef. Fringing reefs are found around much of the
coastline of Kaua'i but remain poorly developed around Niihau. There is
a submerged barrier reef off the western coast of Kaua'i.
The majority of Hawai'i's reefs are
located northwest of the main Hawaiian Islands. These are found on the
smaller islands of Nihoa, Necker, French Frigate Shoals, Gardner
Pinnacles, Laysan and Lisianski Islands, and the Pearl, Hermes, Midway
and Kure Atolls. The location of the Hawaiian Islands, in considerable
location and on the northern edge of the tropics, has meant that they
are not highly diverse. Their isolation has been emphasized by the
dominant oceanic currents which reduce the likelihood of pelagic larvae
being carried to the archipelago from other areas. Over millions of
years one consequence of this has been the considerable opportunities
for the development of new species. Some 52 species of stony coral, 500
of nearshore fish, 1,000 of marine mollusks, and 450 of marine algae
have been recorded, of which typically about 25 percent of each of these
and other groups are endemic to the Hawaiian Islands and a few nearby
reefs. This is the highest level of endemism for any coral reef area in
the world. One particular feature of Hawaiian coral reefs is the
relative scarcity of acroporid corals, the major reef builders in most
parts of the Pacific.
Millions of seabirds nest in the
northwest Hawaiian Islands, and a number of migratory shorebirds nest or
overwinter here. These are among the largest and most important seabird
colonies in the Pacific Ocean. Five species of marine turtles have been
seen in Hawaiian waters, and the French Frigate Shoals are one of the
largest remaining nesting grounds for the green sea turtle in the
Pacific. These same islands are also of critical importance for the
Hawaiian monk seal Monachus shauinslandi. The closest relatives
of this seal are the critically endangered Mediterranean monk seal and
the extinct Caribbean monk seal. Although there are about 1,500
individuals and they are highly protected, numbers are still declining.
Several other marine mammals are found in the islands, including a large
and growing population of humpback whales, Megaptera novaegliae,
which spend part of their migratory cycle in the islands between
November and May during which time they mate and give birth.
The Hawaiian Islands are one of the
world's top tourist destinations and consequently only a few of the
residents now live in a manner that could be described as subsistence,
or depend heavily on their own fish catches. There are, however, many
who fish to supplement their diet. for recreational purposes or at
small-scale commercial levels. All of these operate with modern
equipment, including gill nets, spears, trolling, surround nets and
traps. In addition to these, recreational and commercial collection of
fish for aquaria is widespread and poorly regulated. The nearshore fish
populations are reported to be depleted around nearly all the main
islands. Larger scale commercial fisheries primarily focus on pelagic
species, but also concentrate on a number of reef species. A spiny
lobster fishery in the northwestern islands is reported to be severely
overfished and may be closed. More recently a major shark fin fishery
has developed which is extremely controversial, not least because of the
waste and cruelty of returning living sharks to the water with no fins.
European settlement led to radical
changes in the terrestrial environment, with the degradation or
clearance of large tracts of native forest by settlers and the
feral animals (goats and deer in particular) that accompanied them.
These changes have also let to considerable sedimentation in nearshore
environments and may have killed many reef communities. Hawai'i is also
one of the few places where significant numbers of exotic species have
been introduced to the coral reef environment, including marine algae
and fish. There is evidence that these are spreading and may be
displacing resident reef species in some areas.
With urbanization there have been
problems of sewage discharge in a number of areas. Efforts to reduce
this have led to better treatment in some places, but also to more
remote discharge into deeper waters. The overall effects of the latter
approach remain controversial, but are still likely to be impacting
reefs in some areas.
Tourism is the major industry in
Hawai'i, heavily focused on locations on the larger islands. Coastal
tourism developments, including golf courses, may be adding to the
stresses by wider coastal development, effluent discharge and the
physical disturbance of nearshore communities. Diving and snorkelling
are popular , although limited in some areas by rough seas and currents.
Hana'uma Bay, the most popular snorkelling destination on Oahu, receives
up to 10,000 visitors per day.
Efforts to regulate and protect coral
reefs in Hawai'i include a large number of marine protected areas.
Federal legislation covers most of the more remote islands and their
surrounding reefs as national wildlife refuge. In 2000 all of the other
reefs and shallow banks which lay outside these declared refuges,
together with a very large area of surrounding seas, were declared a
Coral Reef Ecosystem Reserve. The combined legislation for these areas
has created a contiguous marine protected area, second in size only to
the great Barrier Reef in Australia. Among the main islands the
Hawaiian Humpback Whale National Marine Sanctuary covers significant
areas of offshore waters. Closer to centers of human population there
are several sites protected at the state level. The degree of protection
afforded by these varies considerably.
The US minor outlying islands
include American Samoa, Guam and the
Northern Mariana Islands but also a number of remote atolls and reefs in
the Central Pacific. Their importance in terms of biodiversity is now
increasingly recognized. These include Baker and Howland Islands, the
Phoenix Islands of Kiribati, Jarvis Island, Johnston and Wake
OFFICIAL, SCIENTIFIC &
Carl Meyer's Home Page: Hawaiian Coral Reef Topics
Coral Reef Network: Hawaii
Hawaii Coastal Zone Management
Hawaii Wildlife Fund
Hawaiian Whale Reseach Foundation
Hawaiian Islands Coral Reef Ecosystem Reserve
Turtle Trax: Green Sea turtles on Maui
Enchanted Lake Elementary School's "Venture into
Hawaii's Coral Reefs"
NOAA Center For Coastal Monitoring and
Assessement: Coral Reef Report -Hawaii
Save Our Seas Hawaii Based Site
Alternative Hawaii- The Hawaii Ecotourism Site
Robinson's Diving World Adventures
Maui Scuba Diving
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.