P
PACIFIC CORAL REEFS: AN INTRODUCTION
James E. Maragos
1
, Gareth J. Williams
2
1
U.S. Fish and Wildlife Service, Honolulu, HI, USA
2
Victoria University of Wellington, Wellington,
New Zealand
Introduction
This entry introduces coral reefs and associated archipelagos within or facing the Pacific Ocean, including those
not sheltered behind adjacent western seas (Japan, Yellow,
South China, Sulu, Celebes, Banda, Arafura); continents
(Australia, Asia), and sub-continents (SE Asia,
New Guinea). The Great Barrier Reef of Eastern Australian is within the Pacific Ocean but, like other regions, is
covered in more detail in separate entries. A total of 47
archipelagos and isolated reefs and islands under the jurisdiction of 31 nations and territories in the Pacific are covered here and listed in Table 1. The location and current
names of most of the archipelagos and some of the nations
are shown in Figure 1. It is impossible to list and show all
the governments and archipelagoes on one map or accurately estimate the number of tropical islands and reefs
in the Pacific. However, there are likely more than
10,000 islands and associated reefs, far more than reported
in Table 1, which focuses mostly on the larger inhabited
Pacific islands.
The Pacific supports the largest tropical and subtropical habitat for coral reefs in the world at about 58%
of the global total, amounting to approximately 88 million
km
2 between latitudes of 30
N to 30
S, based upon distance and area calculations of Google Earth imagery. This
compares to about 35 million km
2 of habitat for the Indian
Ocean, about 17 million km
2 of habitat for the Gulf of
Mexico-Caribbean Sea, and 13 million km
2 of habitat for
SE Asia. Along the Equator, the Pacific stretches from
127
E (off the eastern coast of Haimahera Island, north
of New Guinea Island) to 80
W (off the western coast
of Ecuador near Quito), a distance of 16,900 km and
accounting for 42% of the circumference of the earth.
Although the Pacific’s huge size supports much larger
numbers of coral reefs, tropical islands, large reefs, and
habitat compared to those in the Indian Ocean and Gulf
of Mexico-Caribbean Sea, the Pacific island number and
size totals are less than those within SE Asia; much of
the tropical and subtropical habitat in the Pacific is devoid
of islands and reefs.
Categories of reefs in the Pacific Ocean
All coral reefs begin as coral and/or coralline algal communities either along the sides and tops of emergent volcanoes near or above the sea surface within the Pacific
Ocean basin or on preexisting substrates of the continents
or continental islands bordering the Pacific. Periods of
subsequent subsidence or uplift, tectonic plate movements, sea-level rises and falls, and other epochs of unfavorable ocean temperatures and chemistry during the
Mesozoic and Cenozoic likely led to massive drowning,
dissolution, and subduction of many ancient reefs. Not
all of these were restored following the return of favorable
conditions for their growth and survival. This chapter
covers only living Pacific reefs comprising:
1. Fringing reefs – coral reefs that grow out and upwards
to the sea surface directly from the shoreline of mostly
volcanic or continental islands (Figure 2), starting out
as aprons that may eventually encircle the fringes of
islands and form shallow reef crests or flats.
2. Barrier reefs – linear offshore reefs that encircle subsiding or emerging volcanic islands offshore or on continental shelves beyond shallow lagoons that separate
the barrier reefs from the island or continent (Figure 3).
David Hopley (ed.), Encyclopedia of Modern Coral Reefs, DOI 10.1007/978-90-481-2639-2,
# Springer Science+Business Media B.V. 2011
PACIFIC CORAL REEFS: AN INTRODUCTION
James E. Maragos
1
, Gareth J. Williams
2
1
U.S. Fish and Wildlife Service, Honolulu, HI, USA
2
Victoria University of Wellington, Wellington,
New Zealand
Introduction
This entry introduces coral reefs and associated archipelagos within or facing the Pacific Ocean, including those
not sheltered behind adjacent western seas (Japan, Yellow,
South China, Sulu, Celebes, Banda, Arafura); continents
(Australia, Asia), and sub-continents (SE Asia,
New Guinea). The Great Barrier Reef of Eastern Australian is within the Pacific Ocean but, like other regions, is
covered in more detail in separate entries. A total of 47
archipelagos and isolated reefs and islands under the jurisdiction of 31 nations and territories in the Pacific are covered here and listed in Table 1. The location and current
names of most of the archipelagos and some of the nations
are shown in Figure 1. It is impossible to list and show all
the governments and archipelagoes on one map or accurately estimate the number of tropical islands and reefs
in the Pacific. However, there are likely more than
10,000 islands and associated reefs, far more than reported
in Table 1, which focuses mostly on the larger inhabited
Pacific islands.
The Pacific supports the largest tropical and subtropical habitat for coral reefs in the world at about 58%
of the global total, amounting to approximately 88 million
km
2 between latitudes of 30
N to 30
S, based upon distance and area calculations of Google Earth imagery. This
compares to about 35 million km
2 of habitat for the Indian
Ocean, about 17 million km
2 of habitat for the Gulf of
Mexico-Caribbean Sea, and 13 million km
2 of habitat for
SE Asia. Along the Equator, the Pacific stretches from
127
E (off the eastern coast of Haimahera Island, north
of New Guinea Island) to 80
W (off the western coast
of Ecuador near Quito), a distance of 16,900 km and
accounting for 42% of the circumference of the earth.
Although the Pacific’s huge size supports much larger
numbers of coral reefs, tropical islands, large reefs, and
habitat compared to those in the Indian Ocean and Gulf
of Mexico-Caribbean Sea, the Pacific island number and
size totals are less than those within SE Asia; much of
the tropical and subtropical habitat in the Pacific is devoid
of islands and reefs.
Categories of reefs in the Pacific Ocean
All coral reefs begin as coral and/or coralline algal communities either along the sides and tops of emergent volcanoes near or above the sea surface within the Pacific
Ocean basin or on preexisting substrates of the continents
or continental islands bordering the Pacific. Periods of
subsequent subsidence or uplift, tectonic plate movements, sea-level rises and falls, and other epochs of unfavorable ocean temperatures and chemistry during the
Mesozoic and Cenozoic likely led to massive drowning,
dissolution, and subduction of many ancient reefs. Not
all of these were restored following the return of favorable
conditions for their growth and survival. This chapter
covers only living Pacific reefs comprising:
1. Fringing reefs – coral reefs that grow out and upwards
to the sea surface directly from the shoreline of mostly
volcanic or continental islands (Figure 2), starting out
as aprons that may eventually encircle the fringes of
islands and form shallow reef crests or flats.
2. Barrier reefs – linear offshore reefs that encircle subsiding or emerging volcanic islands offshore or on continental shelves beyond shallow lagoons that separate
the barrier reefs from the island or continent (Figure 3).
David Hopley (ed.), Encyclopedia of Modern Coral Reefs, DOI 10.1007/978-90-481-2639-2,
# Springer Science+Business Media B.V. 2011