The southern mud oyster, Australian flat oyster, native flat oyster, native mud oyster, or angasi oyster (''Ostrea angasi''), is endemic to southern Australia, ranging from

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to ...

to southeast

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

and around

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

. ''Ostrea angasi'' superficially resembles '' Ostrea edulis'' and both species may be referred to with the name "flat oyster". However, the two species do not occur naturally in the same geographic distribution.

Habitat

This species is found in sheltered, silty or sand-bottomed

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environme ...

at depths between 1 and 30 metres.

Diet

Flat oysters, like all other

oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not a ...

species, are

filter feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

s, feeding on, and taking in anything small enough to be filtered in their

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

. This may include

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cr ...

microalgae Microalgae or microphytes are microscopic algae invisible to the naked eye. They are phytoplankton typically found in freshwater and marine systems, living in both the water column and sediment. They are unicellular species which exist indi ...

inorganic In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemis ...

material.

Predators

Oyster growers at Coffin Bay, South Australia have observed stingrays eating their experimental commercial stocks of ''Ostrea angasi''.

Commercial harvesting

Extensive oyster reefs in southern Australia were largely destroyed by over-exploitation during the 19th and early 20th Centuries. Oysters were dredged directly from the seabed. In the 21st century, commercial oyster growers in southern Australia have started experimentally

farming Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peop ...

''O. angasi'' as a means to diversify their businesses. This was prompted by other growers suffering massive stock losses of '' Crassostrea gigas'' resulting from outbreaks of Pacific Oyster Mortality Syndrome (POMS)''.''

Not-for-profit projects

The not-for-profit organisation Estuary Care Foundation was established in

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

to undertake trials growing ''Ostrea angasi'' in the

Port River The Port River (officially known as the Port Adelaide River) is part of a tidal estuary located north of the Adelaide city centre in the Australian state of South Australia. It has been used as a shipping channel since the beginning of European ...

and adjacent waters. The organisation is also involved in

seagrass Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families ( Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the ...

monitoring and restoration work within the Port River.

Windara Reef

Windara Reef was constructed in Gulf St Vincent, offshore from Ardrossan, to promote the reestablishment of ''Ostrea angasi''. The reef was also opened to recreational fishers in 2017. As of April 2019, it was the largest shellfish reef restoration project in the southern hemisphere.

The Nature Conservancy The Nature Conservancy (TNC) is a global environmental organization headquartered in Arlington, Virginia. it works via affiliates or branches in 79 countries and territories, as well as across every state in the US. Founded in 1951, The Natu ...

, the

Australian Government The Australian Government, also known as the Commonwealth Government, is the national government of Australia, a federal parliamentary constitutional monarchy. Like other Westminster-style systems of government, the Australian Government ...

, the

South Australian Government The Government of South Australia, also referred to as the South Australian Government, SA Government or more formally, His Majesty’s Government, is the Australian state democratic administrative authority of South Australia. It is modelled o ...

, the Yorke Peninsula Council, The

University of Adelaide The University of Adelaide (informally Adelaide University) is a public research university located in Adelaide, South Australia. Established in 1874, it is the third-oldest university in Australia. The university's main campus is located on ...

and the

Ian Potter Foundation Sir William Ian Potter (25 August 190224 October 1994), known as Ian Potter, was an Australian stockbroker, businessman and philanthropist. Potter was knighted in 1962. The Ian Potter Foundation, which he established in 1964, has made grants t ...

have each contributed to funding the project.