Habitat and Ecology
Posidonia australis exists in well developed meadows and typically has continuous cover (Cambridge and Kuo 1979). This species is common in the subtidal environments in Western Australia, to depths of about 12 m. It can exist in depths of up to 22 m in clear non-polluted water. It often grows in meadows mixed with Zostera tasmanica and Halophila ovalis in less-protected areas dominated by sandy sediments in southeast region of Australia, and occupies the gaps between meadows and areas close to water inputs. It is a slow growing species.
Posidonia australis is the dominant seagrass species in a number of southeastern Australian estuaries. This species is important for primary productivity in these systems, supports a variety of detritus feeders and macrofauna, and is an important nursery area for fish (Meehan and West 2004).
Few seedlings of this species are seen in the field. Seedlings likely do not play a role in recovery of damaged meadows as they do not form rhizomes quickly and therefore spread slowly (Meehan and West 2004). The recruitment rate (and generation length) is estimated at five years.
Posidonia australis meadows have a low number of loosely packed shoots with upright-standing leaf blades, and thinning-out of upright-standing leaf blades in the top half of the canopy creating an "open" canopy.Posidonia australis meadows are typically much smaller than those of P. sinuosa. Flowers of this species occur in the top of the canopy, within a zone of minimal leaf area. This may lead to fewer obstructions in the pollen dispersal path (Smith and Walker 2002).
Molecular Biology and Genetics
Barcode data: Posidonia australis
Statistics of barcoding coverage: Posidonia australis
Public Records: 1
Specimens with Barcodes: 1
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
The Posidonia community in Jervis Bay, Australia has suffered large declines in the past (Meehan and West 2000). This community has taken over 25 years to recolonize a total area in this bay of 0.4 ha and is likely to take over a century to repair completely, assuming there is no further damage. This recolonization appears to be entirely by vegetative re-growth. This location has excellent water quality and conditions ideal for recovery (Meehan and West 2000).
Cockburn Sound has been subjected to steady degradation since 1954, with the establishment of an oil refinery and the successive establishments of steel works, fertilizer factories, sewage-treatment facilities, and a power station. This has led to contaminated effluents and increased nutrient loads. Between 1954 and 1978 the meadow in this region (containing P. australis) was reduced from 4,200 to 900 ha. (Cambridge and McComb 1984).
Seagrass loss (Posidonia australis and P. sinuosa) in Oyster Harbour between 1962 and 1988 was the culmination of diffuse nutrient and sediment influx from rural catchments but recovery is possible with time. At the rates of growth measured, transplants placed one m apart will grow together to form a meadow in less than five years (Cambridge et al. 2002).
Posidonia australis is a slow growing species and does not form rhizomes quickly and therefore spreads slowly.
Posidonia australis is included in Shark Bay World Heritage Property which contains more than 4000 km of seagrass beds of high density. Seagrass beds cannot be damaged without a permit in the state of New South Wales in Australia. It is also protected in various Marine Protected Areas (MPAs), in Fisheries Acts or in National or Marine Park Acts (Green and Short 2003).
More research is needed regarding conservation planning and population trends should be monitored. Conservation measures needed include site protection and management, increased educational awareness, and legislation and enforcement at the national and local levels.
Posidonia australis is a species of seagrass that occurs in the southern waters of Australia. It is sometimes referred to as Fibreball Weed. The marine plant forms large meadows that are considered to be of high importance to the environmental conservation of the region. Balls of decomposing detritus from the foliage of the plant are found along nearby shore-lines.
A flowering plant occurring in dense meadows, or along channels, in white sand. It is found at depths from 1 metre to 15 metres. Subsurface rhizomes and roots provide stability in the sands it occupies, erect rhizomes and leaves reduce the accumulation of silt.
The leaves are ribbon-like and between 11 an 20 mm wide. They are bright green, perhaps becoming browned with age. The terminus of the leaf is rounded or absent through damage. They arranged in groups with older leaves on the outside, longer and differing in form from the younger leaves they surround.
This species is found in waters around the southern coast of Australia. In Western Australia is occurs in the Shark Bay region, around islands of the Houtman Abrolhos, and southward along the coast of the Swan Coastal Plain. The species is recorded at the edge of the Esperance Plains, the Archipelago of the Recherche, at the southern coast of the southwest region. The range extends to the east to coastal areas of New South Wales, South Australia, Tasmania, and Victoria. A sign of a nearby occurrence of Posidonia is the presence of masses of decomposing leaves on beaches, these form fibrous balls.
This species is contained by the Posidoniaceae family, one of eight occurring in Australia. The ninth member, Posidonia oceanica, is found in the mediterranean sea. The binomial for this species, Posidonia , is given for the god of the seas Poseidon, and australis refers to the southern distribution. The species was first described by Joseph Hooker in Flora Tasmaniae.
- Short, F.T., Carruthers, T.J.R., Waycott, M., Kendrick, G.A., Fourqurean, J.W., Callabine, A., Kenworthy, W.J. & Dennison, W.C. 2010. Posidonia australis. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 9 January 2013.
- "Posidonia australis". FloraBase. Department of Environment and Conservation, Government of Western Australia.
- Mike van Keulen. "The genus Posidonia König (nom. cons.) (Posidoniaceae).". Murdoch University.
- "Humble plants may save the planet". University of Technology, Sydney. 14 August 2013. Retrieved 15 August 2013.
- Hooker, J.D. (1858), The botany of the Antarctic voyage of H.M. discovery ships Erebus and Terror . III. Flora Tasmaniae 2(6): 43 [tax. nov.] f. APNI