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Shellfish reefs

Shellfish reefs


Oyster bank in Ningi creek. Photo by B. Diggles.

Shellfish reefs can be designed to treat and improve water quality. The shellfish reef treatment systems usually use oysters or mussels and can improve water quality in two ways[1]:

  1. As filter-feeders the shellfish draw in suspended sediment along with their planktonic food and lay this down on the substrate as bio-deposits.
  2. They can armour substrates to reduce the re-suspension of fine sediment and protect shorelines from erosion by dampening wave energy

Oysters and mussels are suspension feeders, consuming plankton and non-living material from the water column down to a size fraction of ~3μm.

The filtration of suspended matter in the water column by shellfish can cause a reduction in turbidity, improving light penetration and growing conditions for submerged vegetation, whilst the consumption of phytoplankton releases ammonium as a waste product supporting aquatic vegetation growth.

Oyster reefs are also likely to reduce eutrophication through the reduction in phytoplankton and cycling of nutrients, particularly the removal of nitrogen through denitrification and burial via biodeposition[2].

The main services that shellfish reef treatment provides include:

  • Water treatment
  • Reduced erosion/shoreline protection
  • Habitat
  • Recreation (collection for eating if safe)
  • Food source for crabs, fish


In addition to the standard disclaimer located at the bottom of the page, please note the content presented is based on published knowledge of treatment systems. Many of the treatment systems described have not been trialled in different regions or land uses in Queensland. The information will be updated as new trials are conducted and monitored. If you have any additional information on treatment systems or suggestions for additional technologies please contact us using the feedback link at the bottom of this page.


  1. ^ Chapman, S & McLeod, I (8 July 2016), Shellfish reefs for water quality treatment - presentation to the Treatment Systems in Coastal Catchments Forum. [online], Department of Environment and Heritage Protection. Available at:
  2. ^ Newell, RIE, Fisher, TR, Holyoke, RR & Cornwell, JC (October 2003), 'Influence of Eastern oysters on nitrogen and phosporus regeneration in Chesapeake Bay, USA. In: The Comparative Roles of Suspension Feeders in Ecosystems', Proceedings of the NATO Advanced Research Workshop on The Comparative Roles of Suspension-Feeders in Ecosystems, pp. 93-120.

Last updated: 5 October 2018

This page should be cited as:

Department of Environment and Science, Queensland (2018) Shellfish reefs, WetlandInfo website, accessed 13 May 2021. Available at:

Queensland Government
WetlandInfo   —   Department of Environment and Science