1. Oysters are keystone species aggregating to form complex reef structures
|Remnant flat oyster reef in Port Phillip Bay (photo courtesy Paul Hamer).|
2. Oysters have mighty filtration powers
Oysters improve water quality by filtering algae, nutrients and suspended matter in the water column through their gills. One single oyster filters up to 150 litres of water a day. Now, can you imagine the water filtration capacity of an entire reef! Nature really does do it best.
3. Oyster larvae "hear" through vibrations
Oyster larvae float around in the water column waiting for the perfect opportunity to settle and grow into an adult. Although oysters don't have ears, they have clever abilities which enable them to sense or "hear" their environmental surroundings. Oysters perceive the vibrations created by sound waves using the statocyst: the organ that registers movement and vibration.
4. Oysters have three chambered hearts and colourless bloodOysters breathe much like fish, using both gills and mantle. The mantle is lined with many small, thin-walled blood vessels which extract oxygen from the surrounding water. A small, three-chambered heart pumps colorless blood, with its supply of oxygen, to all parts of the body. At the same time a pair of kidneys located on the underside of the muscle purify the blood of any waste products it has collected.
5. Oyster reefs stabilise shorelines
Ecosystem Services delivered by oyster reefs in Ysebaert et al. 2018, Habitat Modification and Coastal Protection by Ecosystem-Engineering Reef-Building Bivalves.
6. Oyster reefs provide homes for hundreds of other marine species
When oysters cement together, their aggregations form complex habitat creating homes for a great diversity of invertebrates, boosting the density and diversity of the little animals that feed the broader coastal food web. They also act as a nursey grounds supporting the growth of commercially important fish species.
7. Aboriginal Australians consumed oysters for thousands of years
Aboriginal oyster farming is likely the oldest form of aquaculture practiced in Australia. Shell middens are commonplace around Australia's coastlines and provide valuable information about Aboriginal use of the coast and can show changes in diet, behaviour, activities and settlement over the last 12,000 years. One of the most important features of midden places is that the shell can easily be dated using the radiocarbon method of dating. The oldest known Aboriginal shell midden place on the Victorian coast is nearly 12,000 years old.
8. Native Ostrea angasi oyster reefs are functionally extinct in Australia
9. South Australia is home to the largest oyster restoration project in the Southern Hemisphere
South Australia is home to one very large (20 ha to be exact) oyster restoration project: Windara reef, located in the coastal waters of Gulf St Vincent near Ardrossan. It is the largest of its kind in the Southern Hemisphere, made up of 18,000 tonnes of locally sourced limestone providing the initial foundations for reef regeneration. By replacing the hard substrate that once existed in the Gulf, oyster populations can begin to reestablish and thrive.
10. Oyster reefs are being restored across Australia
Reef Builder, an exciting partnership between the Australian Government and The Nature Conservancy aims to bring shellfish reefs back from the brink of extinction. The $20 million investment will rebuild shellfish reefs around the Australian coastline, three of which are located in South Australia. One of these has been constructed at Glenelg, with two more planned for Kangaroo Island and Onkaparinga.
|Glenelg oyster reef construction (photo courtesy of Maritime Constructions)|
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