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Intertidal molluscs on unconsolidated or unknown substrate

Short description

Intertidal mollusc beds on unconsolidated or substrate of unspecified consolidation.

Disclaimer: Ecosystem type descriptions are based on biophysical attributes identified in Central Queensland through expert advice and supported by scientific literature. Not all ecosystem types are mapped based on current inventory, and many of the ecosystems described here may also occur in other parts of Queensland.

Oysters growing on gravel, Manly. Photo by Maria Zann

Classification categories

Select from the links below to view related ecosystem type categories

Long description

Intertidal mollusc beds that do not occur on consolidated substrates, includes razor clams (Pinna bicolour), leaf oysters (Isognomon ephippium) or mussels (Trichomya hirsuta) growing on mud, sand, gravel or boulder substrates. Fourteen species of bivalve mollusc are known to form shellfish reef ecosystems, with their extent in Queensland poorly known[1]. Other shellfish ecosystems grow on, or form, consolidated ecosystem types. Also includes commercially grown oysters (Ostraeidae) Saccostrea cucullata (milky oyster) and Saccostrea glomerata (rock oyster)[1] where they occur on gravel (including cobbles and/or pebbles). These ecosystems may also include encrusting algae, erect macrophyte algae and bryozoans, and mussel beds may include sponges. See types (64, 65, 116, 118).

Special values

There is currently very limited information available regarding the extent, physical characteristics, biodiversity and ecosystem services of Australian shellfish ecosystems, particularly those in unconsolidated sediments and not of commercial importance.

Oysters and mussels are ecosystem engineers that create shellfish reefs that provide, modify and maintain habitats for a range of other species. Shellfish reefs provide a range of ecosystem services, including food provision, fish and invertebrate habitat, water filtration, fish production and shoreline protection.

For thousands of years, Traditional Owners caught and ate large numbers of shellfish species in and around the Queensland coast. See type (116) for further values information.

Diagnostic attributes

Inundation 'Intertidal – Lower low', 'Intertidal – Mid low', 'Intertidal – Upper low', 'Intertidal – Low undifferentiated', 'Intertidal – Lower medium', 'Intertidal – Upper-medium', 'Intertidal – Medium undifferentiated', 'Intertidal – High', 'Intertidal – Undifferentiated', 'Intertidal – High undifferentiated' although usually occurring below mean sea level

Structural macrobiota 'Molluscs – other', 'Molluscs – oysters', 'Molluscs – scallops', 'Other fauna – barnacles'

Consolidation 'Intermediate', 'Unconsolidated', 'Unknown'


Both attributes of Structural macrobiota and Sediment texture may have been modified by previous harvesting of oysters but this modification is unmapped.


Little inventory for the state to date. Mussels, ark shells and sponges formed aggregations in Moreton Bay that may persist but are unsurveyed.

The following relates to distribution of this ecosystem type within the Central Queensland mapping area:

  • In Central Queensland, these ecosystems typically include oysters, with or without barnacles, growing on gravel (including cobbles and/or pebbles), but can grow on mangrove prop roots (e.g. Rhizophora forests, see type 7) or pneumatophores (e.g. Avicennia forests, see type 8). Gravel beds can be in situ (e.g. duricrust) or transported.
  • Oyster beds were heavily harvested from the 1860s to 1920s and transported from Wide Bay and Port Curtis to Moreton Bay[1][2]. Extent poorly known currently, limited mapping available at seascape scale. May have been part of Traditional Owner fish traps, with many moved or displaced by oyster lease holders.


Other relevant attributes include Energy and Sediment texture as mollusc beds typically develop in muds and fine sediments in low energy environments.

Additional Information

Molluscs - Museum of Tropical Queensland

Shellfish Reef Restoration Network


  1. ^ a b c Gillies, CL, McLeod, IM, Alleway, HK, Cook, P, Crawford, C, Creighton, C, Diggles, B, Ford, J, Hamer, P, Heller-Wagner, G, Lebrault, E, Le Port, A, Russell, K, Sheaves, M & Warnock, B (14 February 2018), 'Australian shellfish ecosystems: Past distribution, current status and future direction', PLOS ONE. [online], vol. 13, no. 2, p. e0190914, ed. L D Coen. Available at: [Accessed 25 March 2019].
  2. ^ Saville-Kent, W (1893), The Great Barrier Reef of Australia: Its Products and Potentialities, John Currey, Melbourne, Australia.

Last updated: 22 July 2019

This page should be cited as:

Department of Environment, Science and Innovation, Queensland (2019) Intertidal molluscs on unconsolidated or unknown substrate, WetlandInfo website, accessed 18 March 2024. Available at:

Queensland Government
WetlandInfo   —   Department of Environment, Science and Innovation