Skip links and keyboard navigation

Undifferentiated coral on unconsolidated substrate in shallow to deep water

Short description

Subtidal corals in shallow to deep water on unconsolidated substrates.

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.

Coral at Hoffmans Rocks. Photo by Tom Davis

Classification categories

Select from the links below to view related ecosystem type categories

Long description

Subtidal corals in shallow (0 to 10 metres) to deep water (10 to 30 metres) on unconsolidated or intermediate substrates including boulder, gravel (i.e. cobble and pebble), sand, mud and/or coffee rock. This type includes any undifferentiated coral as the dominant taxa on either reefal gardens, pre-reefal hard corals (gravel), soft corals and/or other octocorallians* or mixed hard and octocorallian taxa which cannot be split into types 70 (undifferentiated coral on unconsolidated), 78 (branching corals), 86 (non-branching hard corals on unconsolidated) or 98 (soft coral reefal gardens on unconsolidated). Subdominant taxa may be sponge or bryozoans and erect calcareous/erect macrophyte algae may be present.

Refer to type 70 (undifferentiated corals on unconsolidated) for comments concerning the origin of many Great Barrier Reef fringing reefs on unconsolidated sediments[4].

*Octocorallia is a subclass of the class Anthozoa in the phylum Cnidaria, and include soft corals, gorgonians, sea whips, sea pens, sea fans and octocorals. Like some of the many other anthozoans, octocorallians are sessile polyp-bearing animals with a mobile larval phase. Octocorallians are distinguished by the eight (i.e. octo) tentacles in each polyp. Most octocorallians do not deposit a rigid calcium carbonate exoskeleton, and therefore tend to attach to reefs rather than contribute to reefal frameworks as per the reef building Scleractinian (hard) corals[2].

Special values

The values of Queensland’s coral reefs are internationally recognised in the World Heritage and Ramsar conventions. The Outstanding Universal Value of the Great Barrier Reef World Heritage area is based on four criteria (vii), (viii), (ix), (x). The Ramsar convention also includes coral reefs as one of its wetland types which make up part of a site’s ecological character (a combination of the ecosystem components, processes and services of the wetland). The Great Sandy Strait Ramsar wetland also includes coral reefs. Shoalwater and Corio Bays Ramsar wetland and the Moreton Bay Ramsar wetland also includes fringing coral reefs.

Corals growing on unconsolidated substrates provide structure for the attachment of other flora and fauna, e.g. sponges, other invertebrates, macroalgae etc. and may provide shelter for fish. Corally, gravelly, rubbly substrates can be productive areas for gastropod molluscs e.g. cowries, cones and murex.

Diagnostic attributes

Inundation 'Subtidal'

Benthic depth 'Shallow (0-10m)', Deep (10-30m)'

Structural macrobiota 'Hard/soft coral – undifferentiated'

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


Potentially Naturalness qualifiers are relevant. Being able to be shifted by mechanical action means that these ecosystems can be potentially modified by trawling or dredging.


Likely to occur on coral rubble adjacent to existing reef, such as on a reef flat or slope adjacent to a reef. Also likely to occur on boulders and gravel, or even gravels on mud. Potentially these ecosystems may consist of scattered rubble and inventory of gravel surrounding coral ecosystems is recommended.

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

  • Geologies with rocky or gravelly substrates such as Port Curtis may provide suitable substrates for coral settlement, e.g. coral communities on boulders and gravel off Hummock Hill Island[1]. Rubbly gravelly areas surrounding consolidated substrates of Facing Island and Seal Rocks may have this community. The difference between this type and type 62 (subtidal other habitat forming biota) is that corals dominate the structural biota.


Water temperature is critical to all corals as they are sensitive to extremes of heat and cold, resulting in bleaching due to the loss of endosymbiotic dinoflagellates (e.g. zooxanthellae) and therefore the ability to photosynthesise[3].

Additional Information

Protecting the Great Barrier Reef - Queensland Government

Coral - Department of Environment, Science and Innovation

Coral reefs - Queensland Museum

The Reef - Great Barrier Reef Marine Park Authority

Corals of the World

Great Barrier Reef - UNESCO

Nationally (DIWA) and internationally important (Ramsar) wetlands - WetlandInfo

Coral Indicators for the 2017 Gladstone Harbour Report Card - Australian Institute of Marine Science

Reef Report Card 2016 - Queensland Government

Great Barrier Reef Outlook Report - Great Barrier Reef Marine Park Authority

Monitoring inshore reefs - Australian Institute of Marine Science

Reef Check Methods - Reef Check Australia

Coral reefs - Museum of Tropical Queensland

Remote Sensing Research Centre - The University of Queensland


  1. ^ Alquezar, R, Scannell, J & Boyd, W (2011), Coastal fringing reefs of the Burnett Mary Region 2011. A report to the Burnett-Mary Regional Group., Centre for Environmental Management, Central Queensland University, Gladstone, Queensland.
  2. ^ Fabricius, K (2010), 'Octocorallia', in Encyclopedia of Modern Coral Reefs, pp. Chapter-35.
  3. ^ Hoegh-Guldberg, O (1999), 'Climate change, coral bleaching and the future of the world's coral reefs', Marine and Freshwater Research. [online], vol. 50, no. 8, p. 839. Available at: [Accessed 11 June 2019].
  4. ^ Smithers, SG, Hopley, D & Parnell, KE (2006), 'Fringing and nearshore coral reefs of the Great Barrier Reef: episodic Holocene development and future prospects', Journal of Coastal Research, pp. 175-187.

Last updated: 12 July 2019

This page should be cited as:

Department of Environment, Science and Innovation, Queensland (2019) Undifferentiated coral on unconsolidated substrate in shallow to deep water, WetlandInfo website, accessed 25 June 2024. Available at:

Queensland Government
WetlandInfo   —   Department of Environment, Science and Innovation