Posidonia

The algae or Posidonia oceanica (Posidonia oceanica) is an alga, as is believed, but a plant. This species is unique in the Mediterranean and its closest relative in Australia must be sought. Can be found from a few centimeters to about 20 feet deep where there is sufficient light to perform photosynthesis. The meadows of Posidonia often found together with two other marine plants, the Zostera marina and Cymodocea nodosa.

These prairies made two vital functions. The first, being plants, their roots remain subject a substantial sand substrate, which together with the dunes are a nature reserve of sand beaches. The second is the protection of many species of marine predators of you, especially at early stages of his life.

But Neptune is in decline due to fishing ar rossegament that destro ssa the seabed and sand extraction from the seabed to regenerate those beaches because of the massive construction of marinas or blocking the flow of marine sand and building rides that have destroyed the sand dunes have lost their natural environment.
Besides the Posidonia is another threat, which is the tropical seaweed Caulerpa taxifolia, which shifts both the Posidonia and the rest of algae without ap c natural predator of the Mediterranean.

Posidonia oceanica is a seagrass species that is endemic to the Mediterranean Sea. This marine plant forms large underwater meadows that provide important environmental services to the region and beyond. The fruit is free floating and known in Italy as 'the olive of the sea' (l'oliva di mare[1]). Balls of fibrous material from its foliage, known as egagropili, wash up to nearby shorelines.

Contents [hide]
1 Description
2 Range and habitat
3 Taxonomy
4 References
5 External links


[edit] Description

Ball of fibrous material on shoreP. oceanica is a flowering plant. It lives in dense meadows or along channels in sands of the Mediterranean. It is found at depths from 1–35 metres (3.3–110 ft), according to water clarity. Subsurface rhizomes and roots stabilize the plant; erect rhizomes and leaves reduce silt accumulation.

The leaves are ribbon-like, appearing in tufts of 6 or 7, and up to 1.5 metres (4.9 ft) long. Average leaf width is around 10 millimetres (0.39 in). They are bright green, perhaps turning brown with age, and have 13 to 17 parallel veins. The leaf terminus is rounded or sometimes absent because of damage. Leaves are arranged in groups, with older leaves on the outside, longer and differing in form from the younger leaves they surround.

The rhizome type stems are found in two forms: one growing up to 150 centimetres (59 in) beneath the sand and the other rising above the sand. All stems are approximately 10 millimetres (0.39 in) thick and upright in habit. This arrangement of the rhizomes eventually forms a mat; the surface contains the active parts of the plant, whereas the center is a dense network of roots and decomposing stems.

The flowering plant's common name is Neptune grass.[2] In 2006 a huge clonal colony of P. oceanica was discovered south of the island of Ibiza. At 8 kilometres (5.0 mi) across and possibly up to 100,000 years of age, it may be one of the largest and oldest clonal colonies on Earth.[3]

[edit] Range and habitat
This species is found only in the Mediterranean Sea, occupying an area about 3% of the basin, corresponding to a surface area of about 38,000 square kilometres (15,000 sq mi).

A sign of Posidonia is the presence of masses of decomposing leaves on beaches. Such plant material has been used for composting, but Italian laws prohibit the use of marine algae and plants for this purpose.


Illustration of P. oceanica habitat[edit] Taxonomy
The genus name, Posidonia , is named for Poseidon, the Greek god of the seas, and oceanica, the species appellation, refers to its once wider distribution. Carl Linnaeus gave the first botanical description of this species in Systema Naturae, although the genus was then named Zostera. The APG system (1998) and APG II system (2003) accept the genus as constituting the sole genus in the family Posidoniaceae, which it places in the order Alismatales, in the clade monocots. The Angiosperm Phylogeny Website concludes that the three families Cymodoceaceae, Posidoniaceae and Ruppiaceae form a monophyletic group.[4] Earlier systems classified this genus in the family Potamogetonaceae or in the family Posidoniaceae but belonging to order Zosterales.