Adaptations to
The tidal Zone

Australia’s mangroves show remarkable adaptations dealing with frequent saltwater inundation and varying climatic zones from arid to very wet. Mangroves share specialised attributes for growing with excess salt and saturated air-less soils. They also have special growth strategies to facilitate establishment and regeneration. One special attribute promoting sustainability and dispersal of mangroves is their unusual production of live young - vivipary. Such attributes have kept mangroves from extinction for more than 50 million years, and enabled them to occupy tidal areas around the world.

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Stems, Roots & Buttresses

Rhizophora roots

Diversity in Stems, Roots & Buttresses

Adaptations concerning above-ground breathing roots are essential for gas exchange in saturated, non-porous soils depleted in oxygen. Another attribute helping survival in water-saturated environments are structures to support the above-ground mass of the tree. Where roots are unable to penetrate more than a metre or so because of the anaerobic conditions, then lateral support structures provide an important contribution.

Roots above-ground come in various types including: pneumatophores as pencil-like (like Avicennia spp.), stiff conical (like Xylocarpus moluccensis), flexible conical (like Sonneratia alba), elongate conical (like Sonneratia caseolaris, Sonneratia lanceolata); knee roots as thick and knobbly (like Bruguiera spp.), thin and wiry (like Lumnitzera littorea); stilt roots (like Rhizophora spp.); and buttresses as sinuous planks (like Xylocarpus granatum, Heritiera littoralis, Ceriops spp.), and erect ‘fins’ (like Bruguiera X rhynchopetala, Xylocarpus moluccensis). Roots are used by various fauna, but the most notable are the teredo shipworms, plus termites and crabs.

Left - dense tangle of stilt roots of Rhizophora species, near Cairns, Queensland.

  • Exposed cable rootsUnusually exposed cable roots of Avicennia marina.
  • Pneumatophores Distinct pneumatophores of Sonneratia caseolaris.

Beauty is in the bark

Bark characteristics vary in: texture from smooth (like Avicennia marina var. eucalyptifolia), to flaky (like Xylocarpus moluccensis), to fissured (like Lumnitzera spp.), to pustular (like Excoecaria agallocha), to friable & crumbly (like Bruguiera gymnorhiza), to crocodile skin (like Rhizophora apiculata); and colour from red (like seaside Rhizophora stylosa, Avicennia integra), grey (like Avicennia marina var. australasica), white (like Camptostemon schultzii), green (like Avicennia marina var. eucalyptifolia), brown (like Bruguiera pariflora) and black (like Lumnitzera spp.). Bark is used by a range of fauna including insects such as molluscs, termites, ants, boring beetle larvae, crickets and roaches, plus small reptiles like geckos and skinks.

Stem and bark of a young sapling of Rhizophora stylosa, with Littorinids

  • Avicennia marina Avicennia marina and ant.
  • Bruguiera gymnorhiza Bruguiera gymnorhiza
  • Osbornia octodonta Osbornia octodonta
  • Lumnitzera racemosa Lumnitzera racemosa
  • Excoecaria agallocha Excoecaria agallocha

Community Volunteers

A key feature of MangroveWatch is its close partnership between community volunteers and scientists from the James Cook University’s Mangrove Hub. Together they are systematically recording basic data as video and still imagery for assessments of estuarine habitat health.

Armed with expert support, training and advice, MangroveWatch volunteers in key regions are actively contributing to the monitoring of local estuaries and shorelines. An important goal in this phase of the program is to develop a network of like minded groups with the aim of producing public documents that describe important issues affecting local estuaries and mangroves, and their overall health.

Getting Involved

If you would like to find out more about us or if you like to initiate your own MangroveWatch group within your area, please contact someone at the Mangrove Hub. We will be happy to help.

  • Mangrove Hub Facilitator
  • Dr Norm Duke
  • MangroveWatch Ltd
    ABN: 44 153 297 771
  • PO Box 1250,
  • Elanora Q 4221
  • Mangrove Hub Email

Mangrove Watch Brochure

You can download our fact and information sheet (see link below) to get more information about the MangroveWatch programs.

Mangrove Watch Brochure