Perry, C. T., and Hepburn, L. J., 2008. Syn-depositional alteration
of coral reef framework through bioerosion, encrustation
and cementation: taphonomic signatures of reef accretion
and reef depositional events. Earth Science Reviews, 86,
106–144.
Perry C. T., Spencer T., and Kench P. S., 2008. Carbonate budgets
and reef production states: a geomorphic perspective on the ecological phase-shift concept. Coral Reefs, doi:10.1007/s00338008-0418-z.
Scoffin, T., 1992. Taphonomy of coral reefs: a review. Coral Reefs,
11, 57–77.
Scoffin, T. P., Stearn, C., Boucher, D., Frydl, P., Hawkins, C. M.,
Hunter, I. G., and MacGeachy, J. K., 1980. Calcium carbonate
budget of a fringing reef on the west coast of Barbados. I. erosion, sediments and internal structure. Bulletin of Marine Science, 30, 475–508.
Sheppard, C., Dixon, D. J., Gourlay, M., Sheppard, A., and Payet,
R., 2005. Coral mortality increases wave energy reaching shores
protected by reef flats: examples from Seychelles. Estuarine
Coastal and Shelf Science, 64, 223–234.
Symonds, G., Black, K. P., and Young, I. R., 1995. Wave-driven
flow over shallow reefs. Journal of Geophysical Research,
100(2), 2639–2648.
Woodley, J. D., Chornesky, E. A., Clifford, P. A., Jackson, J. B. C.,
Kaufman, L. S., Knowlton, N., Lang, J. C., Pearson, M. P., Porter, J. W., Rooney, M. C., Rylaarsdam, K. W., Tunnicliffe, V. J.,
Wahle, C. M., Wulff, J. L., Curtis, A. S. G., Dallmeyer, M. D.,
Jupp, B. P., Koehl, M. A. R., Neigel, J., and Sides, E. M.,
1981. Hurricane Allen’s Impact on Jamaican coral reefs.
Science, 214, 749–755.
Woodroffe, C. D., 2003. Reef-island sedimentation on Indo-Pacific
atolls and platform reefs. Proceedings 9th International Coral
Reef Symposium, Bali, 2, 1187–1192.
Wright, D. L., and Thom, B. G., 1977. Coastal depositional landforms: a morphodynamic approach. Progress in Physical Geography, 1, 412–459.
Yamano, H., Abe, O., Matsumoto, E., Kayanne, H., Yonekura, N.,
and Blanchon, P., 2003. Influence of wave energy on Holocene
coral reef development: an example from Ishigaki Island,
Ryukyu Islands, Japan. Sedimentary Geology, 159, 27–41.
Cross-references
Carbonate Budgets and Reef Framework Accumulation
Cay Formation
Climate Change and Coral Reefs
Corals: Environmental Controls on Growth
Ecomorphology
Geomorphic Zonation
Sea Level Change and Its Effect on Reef Growth
Sediments, Properties
ECOMORPHOLOGY
Colin D. Woodroffe
University of Wollongong, Wollongong, NSW, Australia
Definition
Ecomorphology describes the interrelationship between
coral growth form and the dominant environmental factors
that influence reefs. It derives from a growth-form
response that was suggested by John Chappell in 1980.
Introduction
A coral reef comprises a limestone substrate across which
various organisms are distributed, competing for, and
partitioning, space in response to a series of environmental
factors, such as light, sediment and wave energy. These
factors vary across the reef and represent stresses to which
organisms such as the corals respond. The various corals,
adopting distinct growth-forms, have discrete tolerances
and their distribution appears related to environmental
gradients in these stresses. An ecomorphological zonation
based on these principles was outlined by Chappell
(1980).
Environmental stresses and their effect on corals
Chappell (1980) hypothesized growth-form responses in
corals to four gradients in environmental parameters.
Figure 1 is indicative of the sort of responses that he envisaged. (1) Light response: corals require light in order that
their symbiotic zooanthellae can photosynthesize, and
where light is abundant growth forms can support extensive polyp-covered surfaces in comparison with their
projected surface area. Digitate plate and compound plate
morphologies can occur near the water surface where light
is abundant, being replaced by corals with less polypcovered surface at greater depth (Figure 1). (2) Hydrodynamic stress: delicate forms of coral are fractured if wave
energy is high, and only more robust forms with greater
structural strength can persist where wave energy is
greatest. (3) Sediment flux effect: although recent research
indicates that reefs can support diverse coral communities
in some turbid settings, sediment can smother polyps and
limit growth. Platy growth forms are more prone to smothering than those that do not have extensive horizontal surfaces. (4) Subaerial exposure: at lowest tides, exposure of
coral polyps exerts a stress on corals. Flat-topped
microatolls (discoid corals that are living on the margins
but dead on top) and encrusting forms are best adapted
to such exposure.
Variation in coral communities across a section
of reef
Wave energy is one of the most important controls on reefs
and has received considerable study. Corals are often welldeveloped where wave energy is high, although the most
exposed reef crests are generally dominated by coralline
algae, often forming a distinct rim. Wave energy is
a function of wave height squared and decreases with
depth down the reef front. Fragile branching corals are
prone to breakage and can only survive where wave
energy is low; they are replaced by structurally stronger
corals, such as globose or encrusting forms in higher
wave-energy settings (Figure 1).
Corals also have to cope with a range of light conditions; for instance, the massive West Indian coral
Montastrea annularis changes its form, becoming flatter
and more platy with depth down a reef front. Platy corals
are poorly-adapted to tolerate high sediment loads;
ECOMORPHOLOGY
363
of coral reef framework through bioerosion, encrustation
and cementation: taphonomic signatures of reef accretion
and reef depositional events. Earth Science Reviews, 86,
106–144.
Perry C. T., Spencer T., and Kench P. S., 2008. Carbonate budgets
and reef production states: a geomorphic perspective on the ecological phase-shift concept. Coral Reefs, doi:10.1007/s00338008-0418-z.
Scoffin, T., 1992. Taphonomy of coral reefs: a review. Coral Reefs,
11, 57–77.
Scoffin, T. P., Stearn, C., Boucher, D., Frydl, P., Hawkins, C. M.,
Hunter, I. G., and MacGeachy, J. K., 1980. Calcium carbonate
budget of a fringing reef on the west coast of Barbados. I. erosion, sediments and internal structure. Bulletin of Marine Science, 30, 475–508.
Sheppard, C., Dixon, D. J., Gourlay, M., Sheppard, A., and Payet,
R., 2005. Coral mortality increases wave energy reaching shores
protected by reef flats: examples from Seychelles. Estuarine
Coastal and Shelf Science, 64, 223–234.
Symonds, G., Black, K. P., and Young, I. R., 1995. Wave-driven
flow over shallow reefs. Journal of Geophysical Research,
100(2), 2639–2648.
Woodley, J. D., Chornesky, E. A., Clifford, P. A., Jackson, J. B. C.,
Kaufman, L. S., Knowlton, N., Lang, J. C., Pearson, M. P., Porter, J. W., Rooney, M. C., Rylaarsdam, K. W., Tunnicliffe, V. J.,
Wahle, C. M., Wulff, J. L., Curtis, A. S. G., Dallmeyer, M. D.,
Jupp, B. P., Koehl, M. A. R., Neigel, J., and Sides, E. M.,
1981. Hurricane Allen’s Impact on Jamaican coral reefs.
Science, 214, 749–755.
Woodroffe, C. D., 2003. Reef-island sedimentation on Indo-Pacific
atolls and platform reefs. Proceedings 9th International Coral
Reef Symposium, Bali, 2, 1187–1192.
Wright, D. L., and Thom, B. G., 1977. Coastal depositional landforms: a morphodynamic approach. Progress in Physical Geography, 1, 412–459.
Yamano, H., Abe, O., Matsumoto, E., Kayanne, H., Yonekura, N.,
and Blanchon, P., 2003. Influence of wave energy on Holocene
coral reef development: an example from Ishigaki Island,
Ryukyu Islands, Japan. Sedimentary Geology, 159, 27–41.
Cross-references
Carbonate Budgets and Reef Framework Accumulation
Cay Formation
Climate Change and Coral Reefs
Corals: Environmental Controls on Growth
Ecomorphology
Geomorphic Zonation
Sea Level Change and Its Effect on Reef Growth
Sediments, Properties
ECOMORPHOLOGY
Colin D. Woodroffe
University of Wollongong, Wollongong, NSW, Australia
Definition
Ecomorphology describes the interrelationship between
coral growth form and the dominant environmental factors
that influence reefs. It derives from a growth-form
response that was suggested by John Chappell in 1980.
Introduction
A coral reef comprises a limestone substrate across which
various organisms are distributed, competing for, and
partitioning, space in response to a series of environmental
factors, such as light, sediment and wave energy. These
factors vary across the reef and represent stresses to which
organisms such as the corals respond. The various corals,
adopting distinct growth-forms, have discrete tolerances
and their distribution appears related to environmental
gradients in these stresses. An ecomorphological zonation
based on these principles was outlined by Chappell
(1980).
Environmental stresses and their effect on corals
Chappell (1980) hypothesized growth-form responses in
corals to four gradients in environmental parameters.
Figure 1 is indicative of the sort of responses that he envisaged. (1) Light response: corals require light in order that
their symbiotic zooanthellae can photosynthesize, and
where light is abundant growth forms can support extensive polyp-covered surfaces in comparison with their
projected surface area. Digitate plate and compound plate
morphologies can occur near the water surface where light
is abundant, being replaced by corals with less polypcovered surface at greater depth (Figure 1). (2) Hydrodynamic stress: delicate forms of coral are fractured if wave
energy is high, and only more robust forms with greater
structural strength can persist where wave energy is
greatest. (3) Sediment flux effect: although recent research
indicates that reefs can support diverse coral communities
in some turbid settings, sediment can smother polyps and
limit growth. Platy growth forms are more prone to smothering than those that do not have extensive horizontal surfaces. (4) Subaerial exposure: at lowest tides, exposure of
coral polyps exerts a stress on corals. Flat-topped
microatolls (discoid corals that are living on the margins
but dead on top) and encrusting forms are best adapted
to such exposure.
Variation in coral communities across a section
of reef
Wave energy is one of the most important controls on reefs
and has received considerable study. Corals are often welldeveloped where wave energy is high, although the most
exposed reef crests are generally dominated by coralline
algae, often forming a distinct rim. Wave energy is
a function of wave height squared and decreases with
depth down the reef front. Fragile branching corals are
prone to breakage and can only survive where wave
energy is low; they are replaced by structurally stronger
corals, such as globose or encrusting forms in higher
wave-energy settings (Figure 1).
Corals also have to cope with a range of light conditions; for instance, the massive West Indian coral
Montastrea annularis changes its form, becoming flatter
and more platy with depth down a reef front. Platy corals
are poorly-adapted to tolerate high sediment loads;
ECOMORPHOLOGY
363