Heatwole, H., 1994. Colonization of coral islands. In Stevenson,
R. E., and Talbot, F. H. (eds.), Islands. Surrey Hills (Australia):
Reader’s Digest, pp. 56–65.
Lesko, G. L., and Walker, R. B., 1969. Effect of sea water on seed
germination in two pacific atoll beach species. Ecology, 50,
730–734.
Rogers, R. W., 1989. The influence of sea turtles on the terrestrial
vegetation of Heron Island, Great Barrier Reef. Proceedings of
the Royal Society of Queensland, 100, 67–70.
Smith, J. M. B., Heatwole, H., Jones, M., and Waterhouse, B. M.,
1990. Drift disseminules on cays of the Swain Reefs,
Great Barrier Reef, Australia. Journal of Biogeography, 17,
5–17.
Wiens, H. J., 1962. Atoll environment and ecology, New Haven:
Yale University Press.
Cross-references
Coral Cay Classification and Evolution
Cay Formation
Unvegetated Cays
Vegetated Cays
CORAL REEF, DEFINITION
Terry Done
Australian Institute of Marine Science, Townsville MC,
QLD, Australia
Definition
Coral reef: A tract of corals growing on a massive, waveresistant structure and associated sediments, substantially
built by skeletons of successive generations of corals and
other calcareous reef-biota.
Coral-algal reef: A rigid wave-resistant structure in which
scleractinian (stony) corals and crustose coralline algae
are the dominant frame-builders. The term “modern” is
used to refer to reefs that are forming or have formed in
response to late Holocene sea levels (less than 7000 years
B.P.) (James and Macintyre 1985).
Introduction
Drawing a parallel with a definition of the coral reef’s
nearest terrestrial equivalent “forest” as “large tract covered with trees and undergrowth” (Fowler, 1929), “coral
reef” could simply be defined as “large tract covered with
corals and undergrowth.” However, these words fall well
short of capturing a coral reef’s total character on two
major fronts (Stoddart, 1969): first, the notion that the
organisms of the reef themselves do not simply cover
a tract, but also contribute to its nonliving physical structure (Figure 1) in a way that has no parallel in forests; second, the rich and complex ecological systems of which the
corals are part. Documentation of variation in form and
process started with Darwin’s (1842) recognition of oceanic fringing reefs, barrier reefs, and atolls as
a developmental series on subsiding volcanic islands.
Such reefs, whose surrounding water depths and thickness
exceed 1,000 m, represent the outcome of episodes of reef
growth, punctuated by sea-level change, since the Tertiary
(Hopley et al., 2007). Other impressive coral reefs are
much thinner and much younger, exemplified by reefs
on the shallowest parts of continental shelves that
were >100 m above sea level as recently as 20,000 y BP
and became inundated as recently as 7,000 y BP. There,
water depths and reef thickness can be less than a few
meters, the entire entity representing reef initiation and
growth of the mid to late Holocene epoch (Kennedy and
Woodroffe, 2002).
A terminology for coral reefs based on their relationship to land mass and depth of surrounding water
(Figure 2c; see also James and Macintyre, 1985; Spalding
et al., 2001) includes the following: “fringing reef ” (a linear reef with a reef flat some tens of meters across, growing along shelving coastlines and across embayments);
“bank barrier reef ” (another form of linear coastal reef
a little further from the shore than the fringing reef, and
sometimes coalescing with one); “barrier reef ” (also
a linear structure, but fronting deep oceanic waters and
broader – usually hundreds of meters across – and separated from the coastline by navigable waters); “atoll”
(broadly circular reefs enclosing a wide lagoon); “bank
reef ” or “platform reef ” (a substantial reef fitting none of
the above categories, occurring in oceanic and coastal settings). Collectively, these terms account for most of the
large scale morphological variability observed in tropical
coral reefs. Coral reefs that are substantially built by skeletons of successive generations of corals and other calcareous reef-biota also exist in deep, cold waters (Roberts
et al., 2006). However, these “cold-water coral reefs,”
located at depths well below the impact of breaking
waves, are not “wave-resistant” structures in the same
sense as shallow tropical reefs.
Smaller scale morphological variability within and
among reefs is very strongly determined by the “antecedent topography” on which corals established themselves
(Shinn et al., 1977) – i.e., the location, shape and time of
Holocene inundation of topographic sea-floor high points
of stable substrata (e.g., rocks, fluvial rubble, fossil carbonate reefs or dunes). From the mid-Holocene to the present, primary colonization and the upward and outward
accumulation of calcium-carbonate skeletons across that
topography has adorned and obscured its shape to varying
degrees. This transformation has been represented in
whole reefs as a progression through a development series
from “initiation” through “juvenile,” “mature,” and
“senile” stages (Figure 1; see also entry Reef Classification by Hopley (1982)), a scaled-up manifestation of the
series of local scale transitions “a” to “d” in Figure 1 and
Figure 2a. In “resorbed” and “remnant” reef structures
(see entry Reef Classification by Maxwell (1968)),
“degenerative” processes have prevailed, as cumulative
loss of reef material through storms and erosion (both biological and physical) exceeds accumulation of reef material; the net transitions have been in the reverse direction
(e.g., “d” to “c,” “b” or “a”)
CORAL REEF, DEFINITION
261
R. E., and Talbot, F. H. (eds.), Islands. Surrey Hills (Australia):
Reader’s Digest, pp. 56–65.
Lesko, G. L., and Walker, R. B., 1969. Effect of sea water on seed
germination in two pacific atoll beach species. Ecology, 50,
730–734.
Rogers, R. W., 1989. The influence of sea turtles on the terrestrial
vegetation of Heron Island, Great Barrier Reef. Proceedings of
the Royal Society of Queensland, 100, 67–70.
Smith, J. M. B., Heatwole, H., Jones, M., and Waterhouse, B. M.,
1990. Drift disseminules on cays of the Swain Reefs,
Great Barrier Reef, Australia. Journal of Biogeography, 17,
5–17.
Wiens, H. J., 1962. Atoll environment and ecology, New Haven:
Yale University Press.
Cross-references
Coral Cay Classification and Evolution
Cay Formation
Unvegetated Cays
Vegetated Cays
CORAL REEF, DEFINITION
Terry Done
Australian Institute of Marine Science, Townsville MC,
QLD, Australia
Definition
Coral reef: A tract of corals growing on a massive, waveresistant structure and associated sediments, substantially
built by skeletons of successive generations of corals and
other calcareous reef-biota.
Coral-algal reef: A rigid wave-resistant structure in which
scleractinian (stony) corals and crustose coralline algae
are the dominant frame-builders. The term “modern” is
used to refer to reefs that are forming or have formed in
response to late Holocene sea levels (less than 7000 years
B.P.) (James and Macintyre 1985).
Introduction
Drawing a parallel with a definition of the coral reef’s
nearest terrestrial equivalent “forest” as “large tract covered with trees and undergrowth” (Fowler, 1929), “coral
reef” could simply be defined as “large tract covered with
corals and undergrowth.” However, these words fall well
short of capturing a coral reef’s total character on two
major fronts (Stoddart, 1969): first, the notion that the
organisms of the reef themselves do not simply cover
a tract, but also contribute to its nonliving physical structure (Figure 1) in a way that has no parallel in forests; second, the rich and complex ecological systems of which the
corals are part. Documentation of variation in form and
process started with Darwin’s (1842) recognition of oceanic fringing reefs, barrier reefs, and atolls as
a developmental series on subsiding volcanic islands.
Such reefs, whose surrounding water depths and thickness
exceed 1,000 m, represent the outcome of episodes of reef
growth, punctuated by sea-level change, since the Tertiary
(Hopley et al., 2007). Other impressive coral reefs are
much thinner and much younger, exemplified by reefs
on the shallowest parts of continental shelves that
were >100 m above sea level as recently as 20,000 y BP
and became inundated as recently as 7,000 y BP. There,
water depths and reef thickness can be less than a few
meters, the entire entity representing reef initiation and
growth of the mid to late Holocene epoch (Kennedy and
Woodroffe, 2002).
A terminology for coral reefs based on their relationship to land mass and depth of surrounding water
(Figure 2c; see also James and Macintyre, 1985; Spalding
et al., 2001) includes the following: “fringing reef ” (a linear reef with a reef flat some tens of meters across, growing along shelving coastlines and across embayments);
“bank barrier reef ” (another form of linear coastal reef
a little further from the shore than the fringing reef, and
sometimes coalescing with one); “barrier reef ” (also
a linear structure, but fronting deep oceanic waters and
broader – usually hundreds of meters across – and separated from the coastline by navigable waters); “atoll”
(broadly circular reefs enclosing a wide lagoon); “bank
reef ” or “platform reef ” (a substantial reef fitting none of
the above categories, occurring in oceanic and coastal settings). Collectively, these terms account for most of the
large scale morphological variability observed in tropical
coral reefs. Coral reefs that are substantially built by skeletons of successive generations of corals and other calcareous reef-biota also exist in deep, cold waters (Roberts
et al., 2006). However, these “cold-water coral reefs,”
located at depths well below the impact of breaking
waves, are not “wave-resistant” structures in the same
sense as shallow tropical reefs.
Smaller scale morphological variability within and
among reefs is very strongly determined by the “antecedent topography” on which corals established themselves
(Shinn et al., 1977) – i.e., the location, shape and time of
Holocene inundation of topographic sea-floor high points
of stable substrata (e.g., rocks, fluvial rubble, fossil carbonate reefs or dunes). From the mid-Holocene to the present, primary colonization and the upward and outward
accumulation of calcium-carbonate skeletons across that
topography has adorned and obscured its shape to varying
degrees. This transformation has been represented in
whole reefs as a progression through a development series
from “initiation” through “juvenile,” “mature,” and
“senile” stages (Figure 1; see also entry Reef Classification by Hopley (1982)), a scaled-up manifestation of the
series of local scale transitions “a” to “d” in Figure 1 and
Figure 2a. In “resorbed” and “remnant” reef structures
(see entry Reef Classification by Maxwell (1968)),
“degenerative” processes have prevailed, as cumulative
loss of reef material through storms and erosion (both biological and physical) exceeds accumulation of reef material; the net transitions have been in the reverse direction
(e.g., “d” to “c,” “b” or “a”)
CORAL REEF, DEFINITION
261