Cross-references
Adaptation
Climate Change and Coral Reefs
Ecomorphology
Historical Ecology of Coral Reefs
Ocean Acidification, Effects on Calcification
Temperature Change: Bleaching
Tropical Cyclone/Hurricane
Waves and Wave-Driven Currents
COCOS (KEELING) ISLANDS
Colin D. Woodroffe
University of Wollongong, Wollongong, NSW, Australia
Definition
The Cocos (Keeling) Islands are a remote group of islands,
forming a single horseshoe-shaped atoll and an isolated
island, North Keeling, in the eastern Indian Ocean. They
represent the only atoll that Charles Darwin visited and
became central to his theory of coral reef development,
and have played a central role in several subsequent
debates about reef development in relation to sea level.
Introduction
The Cocos (Keeling) Islands are an Australian Territory in
the eastern Indian Ocean, and comprise an atoll that has
had a particularly significant place in the development of
coral reef studies. This was the only coral atoll that
Charles Darwin visited during the voyage of the Beagle,
and it therefore played a particularly central role in his theory of reef development. It was subsequently visited by
several other naturalists. The horseshoe-shaped atoll has
a series of sandy reef islands around its rim and a central
lagoon that is relatively well flushed during southeast
tradewinds, but incompletely flushed during times when
winds blow from the northwest.
History
The Cocos (Keeling) Islands were probably first sighted
by Captain William Keeling in 1609. Captain James
Clunies Ross visited the islands in 1825 and cleared some
vegetation for a settlement. Clunies Ross worked for
Alexander Hare who settled on the islands in 1826 with
a small entourage of workers, and Clunies Ross himself
returned in 1827 and commenced an alternative settlement. Relations between Clunies Ross and Hare deteriorated until Hare left the islands in 1831, after which
Clunies Ross’ family, known as “Kings of the Cocos,”
ran the islands as a coconut plantation. In 1955, they
became a territory of Australia, and in 1978 the Australian
government purchased all the land, except Oceania
House, Clunies Ross’ residence, and the surrounding
grounds.
The atoll became particularly associated with coral
reefs because it was visited from 1 to 12 April 1836 by
Charles Darwin aboard HMS Beagle. During the voyage
across the Pacific, Darwin had deduced his remarkable
“subsidence” theory of coral reef development in which
he considered that a mid-ocean volcanic island would
first be encircled by a fringing reef, but that through gradual subsidence of the volcanic basement and vertical
growth of the surrounding reef, this would progress
through a barrier reef stage, ultimately becoming an
atoll. Darwin made a number of insightful observations
on the Cocos (Keeling) Islands, but he was particularly
pleased because he felt that shoreline erosion and undercutting of coconut trees on West Island supported his theory that the atoll was slowly subsiding. Cocos featured
prominently in Darwin’s book on coral reefs (Darwin,
1842).
The Cocos (Keeling) Islands were subsequently visited
by several other naturalists, in some cases advocating support for alternative theories (Woodroffe and Berry, 1994).
Particularly, detailed observations of the reef islands and
an estimate of the sediment budget were made by Henry
Brougham Guppy during 1888 (Guppy, 1889). Guppy’s
visit was funded by John Murray and several of his observations consequently supported an alternative view advocated by Murray that atolls built out horizontally through
progradation of the reef front. A descriptive account of
the islands appeared in a book entitled Coral and atolls
by Wood-Jones, who spent a year there as the medical doctor during 1905–1906 (Wood-Jones, 1912). Extensive
collections of the fauna and an analysis of the historical
significance of Clunies Ross’ writings were undertaken
by Gibson-Hill (1953) and an account of Darwin’s time
on the atoll was compiled by Armstrong (1991).
Atoll morphology and physical characteristics
The Cocos (Keeling) Islands comprise a southern horseshoe-shaped atoll (South Keeling Islands, hereafter
referred to as Cocos) with more than 20 sandy reef islands
around a shallow lagoon (Figure 1), and a northern reef
island with a small remnant lagoonlet, North Keeling.
These rise from an ocean floor that is about 5,000-m deep,
and are the only seamounts within the discontinuous
Vening Meinesz chain to reach sea level, making Cocos
one of the more isolated atolls.
Cocos is dominated by the southeast trade winds and
has persistent swell from the southeast for most of the
year, refracting around the atoll but breaking on the entire
perimeter. Tidal range is 1.1 m at springs, and the atoll is
influenced by occasional tropical cyclones, although there
is little evidence of severe storms on the reef flat which
does not have large reef blocks or shingle ridges typical
of more storm-prone atolls in the Pacific. During short
periods, particularly in El Niño years when there are only
light winds from the northwest, lagoonal flushing is
reduced and episodes of fish kill and coral death have been
recorded.
COCOS (KEELING) ISLANDS
221
Adaptation
Climate Change and Coral Reefs
Ecomorphology
Historical Ecology of Coral Reefs
Ocean Acidification, Effects on Calcification
Temperature Change: Bleaching
Tropical Cyclone/Hurricane
Waves and Wave-Driven Currents
COCOS (KEELING) ISLANDS
Colin D. Woodroffe
University of Wollongong, Wollongong, NSW, Australia
Definition
The Cocos (Keeling) Islands are a remote group of islands,
forming a single horseshoe-shaped atoll and an isolated
island, North Keeling, in the eastern Indian Ocean. They
represent the only atoll that Charles Darwin visited and
became central to his theory of coral reef development,
and have played a central role in several subsequent
debates about reef development in relation to sea level.
Introduction
The Cocos (Keeling) Islands are an Australian Territory in
the eastern Indian Ocean, and comprise an atoll that has
had a particularly significant place in the development of
coral reef studies. This was the only coral atoll that
Charles Darwin visited during the voyage of the Beagle,
and it therefore played a particularly central role in his theory of reef development. It was subsequently visited by
several other naturalists. The horseshoe-shaped atoll has
a series of sandy reef islands around its rim and a central
lagoon that is relatively well flushed during southeast
tradewinds, but incompletely flushed during times when
winds blow from the northwest.
History
The Cocos (Keeling) Islands were probably first sighted
by Captain William Keeling in 1609. Captain James
Clunies Ross visited the islands in 1825 and cleared some
vegetation for a settlement. Clunies Ross worked for
Alexander Hare who settled on the islands in 1826 with
a small entourage of workers, and Clunies Ross himself
returned in 1827 and commenced an alternative settlement. Relations between Clunies Ross and Hare deteriorated until Hare left the islands in 1831, after which
Clunies Ross’ family, known as “Kings of the Cocos,”
ran the islands as a coconut plantation. In 1955, they
became a territory of Australia, and in 1978 the Australian
government purchased all the land, except Oceania
House, Clunies Ross’ residence, and the surrounding
grounds.
The atoll became particularly associated with coral
reefs because it was visited from 1 to 12 April 1836 by
Charles Darwin aboard HMS Beagle. During the voyage
across the Pacific, Darwin had deduced his remarkable
“subsidence” theory of coral reef development in which
he considered that a mid-ocean volcanic island would
first be encircled by a fringing reef, but that through gradual subsidence of the volcanic basement and vertical
growth of the surrounding reef, this would progress
through a barrier reef stage, ultimately becoming an
atoll. Darwin made a number of insightful observations
on the Cocos (Keeling) Islands, but he was particularly
pleased because he felt that shoreline erosion and undercutting of coconut trees on West Island supported his theory that the atoll was slowly subsiding. Cocos featured
prominently in Darwin’s book on coral reefs (Darwin,
1842).
The Cocos (Keeling) Islands were subsequently visited
by several other naturalists, in some cases advocating support for alternative theories (Woodroffe and Berry, 1994).
Particularly, detailed observations of the reef islands and
an estimate of the sediment budget were made by Henry
Brougham Guppy during 1888 (Guppy, 1889). Guppy’s
visit was funded by John Murray and several of his observations consequently supported an alternative view advocated by Murray that atolls built out horizontally through
progradation of the reef front. A descriptive account of
the islands appeared in a book entitled Coral and atolls
by Wood-Jones, who spent a year there as the medical doctor during 1905–1906 (Wood-Jones, 1912). Extensive
collections of the fauna and an analysis of the historical
significance of Clunies Ross’ writings were undertaken
by Gibson-Hill (1953) and an account of Darwin’s time
on the atoll was compiled by Armstrong (1991).
Atoll morphology and physical characteristics
The Cocos (Keeling) Islands comprise a southern horseshoe-shaped atoll (South Keeling Islands, hereafter
referred to as Cocos) with more than 20 sandy reef islands
around a shallow lagoon (Figure 1), and a northern reef
island with a small remnant lagoonlet, North Keeling.
These rise from an ocean floor that is about 5,000-m deep,
and are the only seamounts within the discontinuous
Vening Meinesz chain to reach sea level, making Cocos
one of the more isolated atolls.
Cocos is dominated by the southeast trade winds and
has persistent swell from the southeast for most of the
year, refracting around the atoll but breaking on the entire
perimeter. Tidal range is 1.1 m at springs, and the atoll is
influenced by occasional tropical cyclones, although there
is little evidence of severe storms on the reef flat which
does not have large reef blocks or shingle ridges typical
of more storm-prone atolls in the Pacific. During short
periods, particularly in El Niño years when there are only
light winds from the northwest, lagoonal flushing is
reduced and episodes of fish kill and coral death have been
recorded.
COCOS (KEELING) ISLANDS
221