Australian shellfish habitats: past distribution, current status and future direction

Dr Chris Gillies1, Dr Ian McLeod2

1The Nature Conservancy, Carlton, Australia, Australia, 2TropWATER, James Cook University , Townsville, Australia


We review the status of marine ecosystems formed primarily by bivalves in Australia including identifying habitat-forming species, assessing their historical and current extent, causes for decline and past and present management.

Fourteen species of bivalves were identified as developing complex, three-dimensional reef or bed habitats in intertidal and subtidal areas across tropical, subtropical and temperate Australia. A dramatic decline in the extent and condition of Australia’s two most common habitat-forming species (Saccostrea glomerata and Ostrea angasi) occurred during the mid-1800s to early 1900s in concurrence with extensive harvesting for food and lime production, habitat modification, disease outbreaks and a decline in water quality.

Despite early attempts during the late 1800s to curb exploitation and initiate their recovery, we identify a dramatic decline in the extent of S. glomerata and O. angasi habitats compared to early European periods. Out of 118 historical locations containing O. angasi reef systems, only one location is still known to exist whilst only five locations are known to still contain S. glomerata reef systems out of 60 historical locations. The introduced oyster Crasostrea gigas is likely to be increasing in extent, whilst data on the remaining 11 habitat- forming species are limited, preventing a detailed assessment of their current status.  A number of restoration projects have recently been initiated across Australia and we propose a number of existing government policies and conservation mechanisms, if enacted, would readily serve to support the future conservation and recovery of Australia’s shellfish habitats.


Chris is the Marine Manger for the Australia program where he oversees the Great Southern Seascapes program. This includes accelerating the conservation and restoration of Australia’s temperate marine coastal habitats with a particular focus on restoring shellfish reefs.

Chris has previously worked across the science and conservation sector in both freshwater and terrestrial environments but his true passion is marine. He was formally the Director of Science at Earthwatch Australia, where he managed the scientific program across Earthwatch’s expedition and citizen science portfolio. He has created a number of terrestrial and marine citizen science projects, established several national practitioner networks and developed corporate sustainability learning programs. He has served as an invertebrate ecologist for both state and federal government environmental agencies and worked for several environmental consultancies.