Environment and Management. Collingwood Victoria: CSIRO,
pp. 156–170.
Duke, N. C., Ball, M. C., and Ellison, J. C., 1998. Factors influencing biodiversity and distributional gradients in mangroves.
Global Ecology and Biogeography Letters, 7, 27–47.
Duke, N. C., Lawn, P., Roelfsema, C., Zahmel, K., Pedersen, D., and
Tack, C., 2005. Changing coastlines in the Fitzroy estuary –
assessing historical change in coastal environments. pp. 6–9,
41–46 In Noble, B., Bell, A., Verwey, P., and Tilden, J. (eds.),
Fitzroy in Focus. Brisbane: Coastal CRC – Cooperative Research
Centre for Coastal Zone, Estuary and Waterway Management,
106 pp.
Frank, T. D., and Jell, J. S., 2006. Recent Developments on
a nearshore, terrigenous-influenced reef: Low Isles Reef, Australia. Journal of Coastal Research, 22, 474–486.
Hall, L., and Richards, G., 2000. Flying Foxes: Fruit and Blossom
Bats of Australia. Sydney: UNSW, 135 pp.
Hopley, D., 1982 The Geomorphologv of the Great Barrier Reef,
New York: Wiley Interscience, 453 pp.
Macintyre, I. G., Toscano, M. A., Lighty, R. G., Bond, G. B., 2004.
Holocene history of the mangrove islands of Twin Cays, Belize,
Central America. Atoll Research Bulletin, 510, 16.
Tomlinson, P. B., 1986. The Botany of Mangroves. Cambridge:
Cambridge University Press, 413 pp.
Woodroffe, C. D., 2002. Coasts: Form, Process and Evolution.
Cambridge: Cambridge University Press.
MANGROVES
Norman C. Duke
University of Queensland, Brisbane, QLD, Australia
Synonyms
Mangrove forest; Mangrove swamp; Mangrove trees; Sea
trees; Tidal forest; Tidal swamp; Tidal wetland
Definition
Mangroves. A tidal habitat comprised of salt-tolerant trees
and shrubs. Comparable to rainforests, mangroves have
a mixture of plant types. Sometimes the habitat is called
a tidal forest or a mangrove forest to distinguish it from
the trees that are also called mangroves.
Mangrove. A tree, shrub, palm, or ground fern, generally
exceeding 0.5 m in height, that normally grows above
mean sea level in the intertidal zone of marine coastal
environments and estuarine margins.
Tidal salt marsh. Small shrubs or herbaceous plants, generally less than 0.5 m in height, that normally grow above
mean sea level in the intertidal zone of marine coastal
environments and estuarine margins.
Tidal salt pan. Flat areas of fine sediments lacking macrophyte vegetation above mean sea level in the intertidal
zone of marine coastal environments and estuarine
margins.
Tidal wetlands. The combination of mangroves, tidal salt
marsh, as salt pan, as habitats distinctly occurring between
mean sea level and the highest tides. In arid and cooler settings, mangroves share this tidal niche, or are replaced with
diminutive halophyte cousins, the tidal saltmarsh, and flat
salt pan expanses with their remarkable microalgal carpet.
Introduction
Mangroves are one of the world’s dominant coastal ecosystems comprised chiefly of flowering trees and shrubs
uniquely adapted to marine and estuarine tidal conditions
(Tomlinson, 1986; Duke, 1992; Hogarth, 1999; Saenger,
2002; FAO, 2007). They form distinctly vegetated and
often densely structured habitat of verdant closed canopies
(Figure 1) cloaking coastal margins and estuaries of equatorial, tropical, and subtropical regions around the world
(Spalding et al., 1997). Mangroves are well known for
their morphological and physiological adaptations coping
with salt, saturated soils, and regular tidal inundation,
notably with specialized attributes like: exposed breathing
roots above ground, extra stem support structures
(Figure 2), salt-excreting leaves, low water potentials
and high intracellular salt concentrations to maintain
favorable water relations in saline environments, and
viviparous water-dispersed propagules (Figure 3).
Mangroves have acknowledged roles in coastal productivity and connectivity (Mumby et al., 2004), often
supporting high biodiversity and biomass not possible otherwise. Mangrove ecosystems are key sources of coastal
primary production with complex trophic linkages (Robertson et al., 1992), as nursery and breeding sites of marine
and arboreal life (Figure 4), and as physical shelter and
a buffer from episodic severe storms, river flows, and large
waves.
In tropical waters, mangrove stands are often
sandwiched between two of the world’s iconic ecosystems
of coral reefs and tropical rainforests. Biota-structured
ecosystems, like these, play a unique role in coastal ecosystem processes via a combination of well-developed
linkages, coupled with transient biota uniquely adapted
to unusual and often dramatic physico-chemical gradients.
Linked and dependent relationships developed over
millennia have become vital to the survival of each biome.
Colonial corals flourish in shallow warm seas of coasts
where mangroves buffer and protect them from land runoff. Mangroves absorb unwanted nutrients and turbid
waters stabilizing otherwise smothering water-borne sediments and depositional shorelines. These specialized plant
assemblages provide important ecosystem services along
with additional acknowledged roles of highly productive
habitat and nursery sites. The consequences in disturbing
these habitats is likely to have unexpected and farreaching impacts on neighboring ecosystems and dependant biota (Duke et al., 2007).
Uniquely mangrove origins and vulnerability
Mangroves are a unique ecological assemblage (Duke
et al., 1998), remarkable for their relatively small number
of widely distributed flowering plants – evolved mostly
post-Cretaceous over the last 60–100 million years. The
relatively recent evolution of these plants may explain
MANGROVES
655
pp. 156–170.
Duke, N. C., Ball, M. C., and Ellison, J. C., 1998. Factors influencing biodiversity and distributional gradients in mangroves.
Global Ecology and Biogeography Letters, 7, 27–47.
Duke, N. C., Lawn, P., Roelfsema, C., Zahmel, K., Pedersen, D., and
Tack, C., 2005. Changing coastlines in the Fitzroy estuary –
assessing historical change in coastal environments. pp. 6–9,
41–46 In Noble, B., Bell, A., Verwey, P., and Tilden, J. (eds.),
Fitzroy in Focus. Brisbane: Coastal CRC – Cooperative Research
Centre for Coastal Zone, Estuary and Waterway Management,
106 pp.
Frank, T. D., and Jell, J. S., 2006. Recent Developments on
a nearshore, terrigenous-influenced reef: Low Isles Reef, Australia. Journal of Coastal Research, 22, 474–486.
Hall, L., and Richards, G., 2000. Flying Foxes: Fruit and Blossom
Bats of Australia. Sydney: UNSW, 135 pp.
Hopley, D., 1982 The Geomorphologv of the Great Barrier Reef,
New York: Wiley Interscience, 453 pp.
Macintyre, I. G., Toscano, M. A., Lighty, R. G., Bond, G. B., 2004.
Holocene history of the mangrove islands of Twin Cays, Belize,
Central America. Atoll Research Bulletin, 510, 16.
Tomlinson, P. B., 1986. The Botany of Mangroves. Cambridge:
Cambridge University Press, 413 pp.
Woodroffe, C. D., 2002. Coasts: Form, Process and Evolution.
Cambridge: Cambridge University Press.
MANGROVES
Norman C. Duke
University of Queensland, Brisbane, QLD, Australia
Synonyms
Mangrove forest; Mangrove swamp; Mangrove trees; Sea
trees; Tidal forest; Tidal swamp; Tidal wetland
Definition
Mangroves. A tidal habitat comprised of salt-tolerant trees
and shrubs. Comparable to rainforests, mangroves have
a mixture of plant types. Sometimes the habitat is called
a tidal forest or a mangrove forest to distinguish it from
the trees that are also called mangroves.
Mangrove. A tree, shrub, palm, or ground fern, generally
exceeding 0.5 m in height, that normally grows above
mean sea level in the intertidal zone of marine coastal
environments and estuarine margins.
Tidal salt marsh. Small shrubs or herbaceous plants, generally less than 0.5 m in height, that normally grow above
mean sea level in the intertidal zone of marine coastal
environments and estuarine margins.
Tidal salt pan. Flat areas of fine sediments lacking macrophyte vegetation above mean sea level in the intertidal
zone of marine coastal environments and estuarine
margins.
Tidal wetlands. The combination of mangroves, tidal salt
marsh, as salt pan, as habitats distinctly occurring between
mean sea level and the highest tides. In arid and cooler settings, mangroves share this tidal niche, or are replaced with
diminutive halophyte cousins, the tidal saltmarsh, and flat
salt pan expanses with their remarkable microalgal carpet.
Introduction
Mangroves are one of the world’s dominant coastal ecosystems comprised chiefly of flowering trees and shrubs
uniquely adapted to marine and estuarine tidal conditions
(Tomlinson, 1986; Duke, 1992; Hogarth, 1999; Saenger,
2002; FAO, 2007). They form distinctly vegetated and
often densely structured habitat of verdant closed canopies
(Figure 1) cloaking coastal margins and estuaries of equatorial, tropical, and subtropical regions around the world
(Spalding et al., 1997). Mangroves are well known for
their morphological and physiological adaptations coping
with salt, saturated soils, and regular tidal inundation,
notably with specialized attributes like: exposed breathing
roots above ground, extra stem support structures
(Figure 2), salt-excreting leaves, low water potentials
and high intracellular salt concentrations to maintain
favorable water relations in saline environments, and
viviparous water-dispersed propagules (Figure 3).
Mangroves have acknowledged roles in coastal productivity and connectivity (Mumby et al., 2004), often
supporting high biodiversity and biomass not possible otherwise. Mangrove ecosystems are key sources of coastal
primary production with complex trophic linkages (Robertson et al., 1992), as nursery and breeding sites of marine
and arboreal life (Figure 4), and as physical shelter and
a buffer from episodic severe storms, river flows, and large
waves.
In tropical waters, mangrove stands are often
sandwiched between two of the world’s iconic ecosystems
of coral reefs and tropical rainforests. Biota-structured
ecosystems, like these, play a unique role in coastal ecosystem processes via a combination of well-developed
linkages, coupled with transient biota uniquely adapted
to unusual and often dramatic physico-chemical gradients.
Linked and dependent relationships developed over
millennia have become vital to the survival of each biome.
Colonial corals flourish in shallow warm seas of coasts
where mangroves buffer and protect them from land runoff. Mangroves absorb unwanted nutrients and turbid
waters stabilizing otherwise smothering water-borne sediments and depositional shorelines. These specialized plant
assemblages provide important ecosystem services along
with additional acknowledged roles of highly productive
habitat and nursery sites. The consequences in disturbing
these habitats is likely to have unexpected and farreaching impacts on neighboring ecosystems and dependant biota (Duke et al., 2007).
Uniquely mangrove origins and vulnerability
Mangroves are a unique ecological assemblage (Duke
et al., 1998), remarkable for their relatively small number
of widely distributed flowering plants – evolved mostly
post-Cretaceous over the last 60–100 million years. The
relatively recent evolution of these plants may explain
MANGROVES
655