Mangrove
as Habitat

Australia’s mangroves and the zone they occupy are used by numerous plants and animals. The biota living in the tidal zone above mean sea level do so because: either, mangroves are there; or, they replace mangroves, or, they are associates. Epiphytes perch on mangroves and flourish in northern wet areas. Mistletoes parasitize mangrove foliage and occur in northern areas also. Saltmarsh species at times replace mangroves, notably in cooler southern areas, as well as in drier places generally. A multitude of animals depend on mangroves for a variety of reasons for shelter, food, breeding and nursery needs.

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Saltmarsh

Saltmarsh – Diminuitive Cousins of Mangroves

Australia’s mangroves share their tidal habitat between mean sea level and the highest tides with another distinct group of plants – the tidal saltmarsh. Saltmarsh plants are largely distinguished from mangroves by their smaller size. They are described as a separate habitat with plants usually less than one half metre tall. This definition of tidal saltmarsh plants differs from the definition of mangroves only by the size and character of the vegetation – where tidal saltmarsh plants form shrubby ground cover. Saltmarsh plants dominate where mangrove plants are excluded by either low temperature or low moisture limitations, a feature which reflects their much hardier nature. Saltmarsh species typically proliferate in cooler areas subject to occasional frosts, but they also dominate in hotter arid conditions where annual rainfall is less than 1500 mm. There is recent evidence of a landscape-scale dynamic equilibrium between these two plant types such that one will replace the other in alternate climatic conditions. The chief driver of this change is rainfall. Some of the more common Australian tidal saltmarsh species include: Halosarcia halocnemoides (Grey Samphire), Halosarcia indica (Brown Head Samphire), Sarcocornia quinqueflora (Beaded Samphire), Sclerostegia arbuscula (Shrubby Glasswort), Sesuvium portulacastrum (Sea Purslane), Sporobolus virginicus (Marine Couch) and Suaeda arbusculoides (Jellybean Plant).

Left - Saltmarsh ‘floral pavement’ bordering mangroves near Bundaberg, Queensland.

  • Mangrove in saltmarsh Tree of Avicennia marina amongst salt marsh bordering Leschenault Inlet, Western Australia.
  • Saltmarsh species Typical saltmarsh species, Sarcocornia quinqueflora.
Pondapple tree

Associates – Occasional Residents with Mangroves

The separation of mangroves and upland plants across the high water mark is not always distinct. Australia’s mangroves sometimes include additional plant species that are not generally considered mangroves. However, some authors argue for the inclusion of some, or all, of these species as mangroves. Generally, the view taken here is that mangroves are those plants that grow almost exclusively in the tidal habitat. Associate species often include: Cerbera manghas, Clerodendron inerme, Dillenia alata, Hibisicus tiliaceous, Melaleuca sp., Pongamia pinnata, Randia fitzalani, plus creepers like Derris trifoliata, and the rare Finlaysonia obovata in the Northern Territory. Furthermore, there is often overlap also with the closely associated habitat of the beach zone where other species of Callophylum, Casuarina, Morinda and Thespesia are commonly found.

Invasive associate under control

A recently introduced pest species is Annona glabra, known as Pond Apple, has invaded mangroves in north eastern Queensland. It is listed in the top 20 Weeds of National Significance in Australia. Since its introduction as graft stock for custard apples, this species has spread aggressively into upstream estuarine areas like the Daintree River Wet Tropics Area. Its’ dispersal appears to have been widened by Cassowaries who like its fruit, and the ready dispersal of its buoyant fruits. An eradication program is currently being undertaken in affected Queensland estuaries by the Queensland Department of Natural Resources.

Right - Invasive Pond Apple trees, Annona glabra, in mangroves of the Daintree River, Queensland.

  • Dillenia alata Fruiting body of Dillenia alata.
  • Saltmarsh species Casuarina clump on higher ground amongst saltmarsh and mangroves.

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