location by an underlying conglomerate platform that was
formed as a reef flat in mid Holocene when the sea level
was higher than present. The islands themselves are largely
sand, with restricted dune development on the most
exposed oceanward shore. Their elevation is generally
3–4 m above modern sea level, and as the latest tide gauge,
installed in 1992, shows evidence of sea-level rise, signs of
inundation in the lowest-lying areas may be an omen of
more frequent flooding in future (Woodroffe, 2008).
Bibliography
Armstrong, P., 1991. Under the Blue Vault of Heaven: A study of
Charles Darwin’s Sojourn in the Cocos (Keeling) Islands. Indian
Ocean Centre for Peace Studies, Western Australia, 120 pp.
Darwin, C., 1842. The Structure and Distribution of Coral Reefs.
Smith, London: Elder and Co., 214 pp.
Gibson-Hill, C. A. (Editor), 1953. Documents relating to John
Clunies Ross, Alexander Hare and the settlement on the
Cocos-Keeling Islands. Journal of the Malayan Branch of the
Royal Asiatic Society, 25, 306.
Guppy, H. B., 1889. The Cocos-Keeling islands. Scottish Geographical Magazine, 5, 281–297, 457–474, 569–588.
Kench, P. S., 1998. Physical processes in an Indian Ocean atoll.
Coral Reefs, 17, 155–168.
Kench, P. S., and McLean, R. F., 2004. Hydrodynamics and sediment flux of hoa in an Indian Ocean atoll. Earth Surface Processes and Landforms, 29, 933–953.
Smithers, S. G., and Woodroffe, C. D., 2000. Microatolls as sealevel indicators on a mid-ocean atoll. Marine Geology, 168,
61–78.
Smithers, S. G., and Woodroffe, C. D., 2001. Coral microatolls and
20th century sea level in the eastern Indian Ocean. Earth and
Planetary Science Letters, 191, 173–184.
Smithers, S. G., Woodroffe, C. D., McLean, R. F., and Wallensky,
E., 1993. Lagoonal sedimentation in the Cocos (Keeling)
Islands, Indian Ocean. In Proceedings of the 7th International
Coral Reef Symposium, Guam, pp. 273–288.
Wood-Jones, F., 1912. Coral and Atolls: A History and Description
of the Keeling-Cocos Islands, with an Account of Their Fauna
and Flora, and a Discussion of the Method of Development
and Transformation of Coral Structures in General. London:
Lovell Reeve, 392 pp.
Woodroffe, C. D., 2008. Reef-island topography and the vulnerability of atolls to sea-level rise. Global and Planetary Change, 62,
77–96.
Woodroffe, C. D., and Berry, P. F., 1994. Scientific studies in the
Cocos (Keeling) Islands: an introduction. Atoll Research Bulletin, 399, 1–16.
Woodroffe, C. D., and McLean, R. F., 1994. Reef Islands of the
Cocos (Keeling) Islands. Atoll Research Bulletin, 403, 1–36.
Woodroffe, C. D., and Falkland, A. C., 1997. Geology and hydrogeology of the Cocos (Keeling) Islands, Indian Ocean. In Vacher,
H. L., and Quinn, T. M. (eds.), Geology and Hydrogeology of
Carbonate Islands. Amsterdam: Elsevier, pp. 885–908.
Woodroffe, C. D., McLean, R. F., Polach, H., and Wallensky, E.,
1990. Sea level and coral atolls: Late Holocene emergence in
the Indian Ocean. Geology, 18, 62–66.
Woodroffe, C. D., McLean, R. F., and Wallensky, E., 1994.
Geomorphology of the Cocos (Keeling) Islands. Atoll Research
Bulletin, 402, 1–33.
Woodroffe, C. D., McLean, R. F., Smithers, S. G., and Lawson, E.,
1999. Atoll reef-island formation and response to sea-level
change: West Island, Cocos (Keeling) Islands. Marine Geology,
160, 85–104.
Cross-references
Atolls
Blue Hole
Conglomerates
Darwin, Charles (1809–1882)
Eastern Indian Ocean – Northern Sector
Indian Ocean Reefs
Microatoll
Subsidence Hypothesis of Reef Development
COLD-WATER CORAL REEFS
André Freiwald
Senckenberg Meeresgeologie, Wilhelmshaven, Germany
Synonyms
Deep-water coral reefs
Definition
Cold-water coral reef. Qualitative term depicting the general contrast to warm-water coral reefs in the tropics and
subtropics. The ambient seawater temperature range of
known cold-water reefs is 4–14
C. The primary framework is constructed by colonial, azooxanthellate
Scleractinia.
Deep-water coral reef. Qualitative term describing the
general bathymetric setting of these reef systems, which
is deeper than 40 m water depth but with the majority
thriving in 200–1500 m depth.
Introduction
Since Linnean times in the eighteenth century, it is known
that azooxanthellate corals form substantial aggregations
in cold and deep waters and in geographic regions far
beyond the shallow-water coral reef belt of the lower latitudes. Until the 1970s, research and sampling of corals in
deep waters was restricted to single beam echo soundings
and dredge hauls. First visual documentations of this type
of ecosystem came from drop cameras and few manned
submersible operations, which shed more light in some
cold-water reef environments (Squires, 1963; Wilson,
1979). The development of advanced hydro-acoustic
sounding systems, such as swath bathymetry and the
wider assessment of remotely operated vehicles (ROVs),
initiated a worldwide burst to study cold-water coral ecosystems all over the world supported by multinational strategic research programs, which attracted biologists,
geologists, and oceanographers to better understand the
environmental controls and functionality of this cosmopolitan type of coral ecosystem. Of the 711 known
azooxanthellate scleractinian species, 622 live in water
depths deeper than 50 m, but only a small group of 6 species is capable to construct reefal framework with
Lophelia pertusa and Madrepora oculata as the most
COLD-WATER CORAL REEFS
225
formed as a reef flat in mid Holocene when the sea level
was higher than present. The islands themselves are largely
sand, with restricted dune development on the most
exposed oceanward shore. Their elevation is generally
3–4 m above modern sea level, and as the latest tide gauge,
installed in 1992, shows evidence of sea-level rise, signs of
inundation in the lowest-lying areas may be an omen of
more frequent flooding in future (Woodroffe, 2008).
Bibliography
Armstrong, P., 1991. Under the Blue Vault of Heaven: A study of
Charles Darwin’s Sojourn in the Cocos (Keeling) Islands. Indian
Ocean Centre for Peace Studies, Western Australia, 120 pp.
Darwin, C., 1842. The Structure and Distribution of Coral Reefs.
Smith, London: Elder and Co., 214 pp.
Gibson-Hill, C. A. (Editor), 1953. Documents relating to John
Clunies Ross, Alexander Hare and the settlement on the
Cocos-Keeling Islands. Journal of the Malayan Branch of the
Royal Asiatic Society, 25, 306.
Guppy, H. B., 1889. The Cocos-Keeling islands. Scottish Geographical Magazine, 5, 281–297, 457–474, 569–588.
Kench, P. S., 1998. Physical processes in an Indian Ocean atoll.
Coral Reefs, 17, 155–168.
Kench, P. S., and McLean, R. F., 2004. Hydrodynamics and sediment flux of hoa in an Indian Ocean atoll. Earth Surface Processes and Landforms, 29, 933–953.
Smithers, S. G., and Woodroffe, C. D., 2000. Microatolls as sealevel indicators on a mid-ocean atoll. Marine Geology, 168,
61–78.
Smithers, S. G., and Woodroffe, C. D., 2001. Coral microatolls and
20th century sea level in the eastern Indian Ocean. Earth and
Planetary Science Letters, 191, 173–184.
Smithers, S. G., Woodroffe, C. D., McLean, R. F., and Wallensky,
E., 1993. Lagoonal sedimentation in the Cocos (Keeling)
Islands, Indian Ocean. In Proceedings of the 7th International
Coral Reef Symposium, Guam, pp. 273–288.
Wood-Jones, F., 1912. Coral and Atolls: A History and Description
of the Keeling-Cocos Islands, with an Account of Their Fauna
and Flora, and a Discussion of the Method of Development
and Transformation of Coral Structures in General. London:
Lovell Reeve, 392 pp.
Woodroffe, C. D., 2008. Reef-island topography and the vulnerability of atolls to sea-level rise. Global and Planetary Change, 62,
77–96.
Woodroffe, C. D., and Berry, P. F., 1994. Scientific studies in the
Cocos (Keeling) Islands: an introduction. Atoll Research Bulletin, 399, 1–16.
Woodroffe, C. D., and McLean, R. F., 1994. Reef Islands of the
Cocos (Keeling) Islands. Atoll Research Bulletin, 403, 1–36.
Woodroffe, C. D., and Falkland, A. C., 1997. Geology and hydrogeology of the Cocos (Keeling) Islands, Indian Ocean. In Vacher,
H. L., and Quinn, T. M. (eds.), Geology and Hydrogeology of
Carbonate Islands. Amsterdam: Elsevier, pp. 885–908.
Woodroffe, C. D., McLean, R. F., Polach, H., and Wallensky, E.,
1990. Sea level and coral atolls: Late Holocene emergence in
the Indian Ocean. Geology, 18, 62–66.
Woodroffe, C. D., McLean, R. F., and Wallensky, E., 1994.
Geomorphology of the Cocos (Keeling) Islands. Atoll Research
Bulletin, 402, 1–33.
Woodroffe, C. D., McLean, R. F., Smithers, S. G., and Lawson, E.,
1999. Atoll reef-island formation and response to sea-level
change: West Island, Cocos (Keeling) Islands. Marine Geology,
160, 85–104.
Cross-references
Atolls
Blue Hole
Conglomerates
Darwin, Charles (1809–1882)
Eastern Indian Ocean – Northern Sector
Indian Ocean Reefs
Microatoll
Subsidence Hypothesis of Reef Development
COLD-WATER CORAL REEFS
André Freiwald
Senckenberg Meeresgeologie, Wilhelmshaven, Germany
Synonyms
Deep-water coral reefs
Definition
Cold-water coral reef. Qualitative term depicting the general contrast to warm-water coral reefs in the tropics and
subtropics. The ambient seawater temperature range of
known cold-water reefs is 4–14
C. The primary framework is constructed by colonial, azooxanthellate
Scleractinia.
Deep-water coral reef. Qualitative term describing the
general bathymetric setting of these reef systems, which
is deeper than 40 m water depth but with the majority
thriving in 200–1500 m depth.
Introduction
Since Linnean times in the eighteenth century, it is known
that azooxanthellate corals form substantial aggregations
in cold and deep waters and in geographic regions far
beyond the shallow-water coral reef belt of the lower latitudes. Until the 1970s, research and sampling of corals in
deep waters was restricted to single beam echo soundings
and dredge hauls. First visual documentations of this type
of ecosystem came from drop cameras and few manned
submersible operations, which shed more light in some
cold-water reef environments (Squires, 1963; Wilson,
1979). The development of advanced hydro-acoustic
sounding systems, such as swath bathymetry and the
wider assessment of remotely operated vehicles (ROVs),
initiated a worldwide burst to study cold-water coral ecosystems all over the world supported by multinational strategic research programs, which attracted biologists,
geologists, and oceanographers to better understand the
environmental controls and functionality of this cosmopolitan type of coral ecosystem. Of the 711 known
azooxanthellate scleractinian species, 622 live in water
depths deeper than 50 m, but only a small group of 6 species is capable to construct reefal framework with
Lophelia pertusa and Madrepora oculata as the most
COLD-WATER CORAL REEFS
225