Neptune grass
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Neptune grass ( Posidonia oceanica ) |
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| ( L. ) Delile |
The Neptune grass ( Posidonia oceanica ) is a species of the Neptune grass family (Posidoniaceae). This aquatic plant thrives in salt water. It is - as the only species of the genus Posidonia , which is otherwise completely native to Australia - native to the Mediterranean. The seagrass meadows that it forms there are the basis of important marine ecosystems . They are known for the sea balls made from them .
description
The Neptune grass is a submerged living ( submerged ), perennial herbaceous plant . Their compact and branched rhizomes have a diameter of 5 to 10 millimeters and their internodes are only 0.5 to 2 millimeters long. The strongly branched roots have a length of up to 40 centimeters and a diameter of 3 to 4 millimeters.
Usually four to six, rarely up to ten leaves stand together in bundles at the end of the branches. The leaf sheath is 3 to 5 centimeters long and 10 to 12 millimeters wide, ears are missing, with age they tear longitudinally and form brush-like bundles of stiff fibers. The simple, flat leaf blade is linear with a length of 40 to 50 centimeters and a width of 5 to 9 millimeters and notched to blunt at its tip. There are 13 to 17 leaf veins .
The flowering period extends from May to June (Malta). The plant forms a 7 to 15 centimeter long inflorescence stem with 4 to 6 centimeters long and 0.5 to 0.8 centimeter wide, foliage-like bracts. The annual inflorescence is 2.5 to 4.5 inches long. The bracts are smaller than the bracts. Each inflorescence contains three to seven hermaphrodite flowers , the terminal flower is always functionally male. A perianth is missing. There are three stamens , the reddish, 2 to 4.5 millimeters long anthers are sessile. The seated scars are covered with star-shaped papillae . The egg-shaped fruits are up to 10 millimeters long.
ecology
growth
In other seagrasses of the genera Zostera or Cymodocea , the main growth takes place in summer. With Posidonia oceanica, however, new leaves only sprout in autumn and winter. This is done with the use of starch reserves in the rhizomes and roots. These reserves are exhausted in the spring and are replenished in the most productive months of April and May. In spring only a few new leaves are planted and in summer, due to the high level of epiphyte coverage of the leaves , growth ceases completely. The first new leaves only appear in August and September, which grow under the protection of the old leaves. The old leaves fall off in October. This production rhythm is explained as an adaptation to the growth with epiphytes, since Posidonia oceanica presumably takes up nutrients mainly through the leaves and is therefore in competition with the epiphytes. By using the winter nutrient supply and the conversion of carbohydrates, leaf biomass can effectively be built up, while epiphytes and phytoplankton are still limited by the low light intensity. The leaves themselves grow from a basal meristem and die from the leaf tip ("conveyor belt system"), which is also interpreted as an adaptation to epiphyte growth.
Multiplication
Posidonia oceanica rarely flowers. Usually only one flower per 10 m² per year (less than 3% of the newly formed shoots) is developed. In warmer years, however, more flowers can form (more than 10% of the newly formed shoots). Young plants that have emerged from seeds are rarely found. Posidonia oceanica reproduces mainly vegetatively via branches of the rhizome.
In the genetic analysis of Neptune grass throughout the Mediterranean, Sophie Amaud-Haond et al. a. from DEEP-Center de Brest in Plouzané found up to 15 km extended (genetically identical) clones. From this length and the growth rates, the researchers deduce an age of up to 80,000 years, making them the oldest living beings in the world.
Occurrence
Unlike all other species of the genus Posidonia , the Neptune grass is found exclusively in the Mediterranean. It occurs in shallow water up to a depth of 40 meters, and in very clear water up to a depth of 50 to 60 meters. It inhabits moving to slightly protected locations in fine sand with good water circulation such as open coasts or the tips of headlands and is often there. Posidonia oceanica also colonizes larger boulders, whereby the roots are transformed into adhesive discs. The plants require oxygenated water without large fluctuations in salinity (33 to 40 ppt) or temperature. The plants die at water temperatures above 20 to 22 ° C, and also at temperatures below 10 ° C.
Use
Posidonia oceanica plays an important role in the climate. The Spanish marine biologist Carlos Duarte from the Mediterranean Institute of the Balearic Islands in Esporles / Mallorca found that seagrass meadows can store twice as much CO 2 as e.g. B. an equally large area of rainforest . Posidonia oceanica is also a breeding space for many fish and a habitat for snails. In addition, it protects coasts from erosion and thus helps to prevent beaches from being eroded. In addition, the seaweed absorbs many nutrients washed into the sea via the rivers , thus protecting the sea from over-fertilization and keeping the water clear and clean.
Dead Neptune grass can also be used as insulation material. The inventor is the Karlsruhe architecture professor Richard Meier, who patented NeptuTherm® as an insulation material . In addition to high thermal insulation and easy recyclability, this insulation material does not need to be added to achieve the legally prescribed fire protection due to the silicate fiber structure of the Neptune grass.
Damage
On the one hand, the seagrass is severely damaged by increasing climate change and the warming of the oceans. Near the Balearic Islands , the growth from sprouts decreased significantly during a marine heat wave ; In addition to sexual reproduction, sprouts are crucial for the spread of the very slow-growing plants. In the western Mediterranean, Neptune grass meadows could functionally become extinct by the middle of the century.
On the other hand, Posidonia oceanica is torn out of the seabed and destroyed by anchored ships. Between the Balearic islands of Formentera and Ibiza there has been a natural park recognized by UNESCO and included on the UNESCO World Heritage list , the Parque Natural de Ses Salines d'Eivissa i Formentera , since 1999 . The largest contiguous areas on Posidonia oceanica located there are considerably damaged and reduced every year by heavy motorboat traffic and anchored yachts. In the summer of 2011, the marine biologist Manu San Felixe from Formentera filmed how the 100-meter-long motor yacht Turama destroyed one hectare of seaweed in a single day. If the damage persists, the seaweed could have disappeared in three years.
Systematics and botanical history
The Neptune grass was first described by Carl von Linné as Zostera oceanica in 1767 . Karl Dietrich Eberhard Koenig described Posidonia as a separate genus in 1805 and described the Neptune grass as a type species under the name Posidonia caulini . However, the species name was not valid, which is why Alire Raffeneau Delile described the species again in 1813 as Posidonia oceanica and now also validly.
proof
- ^ A b c d e S. M. Haslam, PD Sell, PA Wolseley: A Flora of the Maltese Islands. Msida (Malta) 1977, pp. 374-375.
- ↑ a b c d J. Borum, CM Duarte, D. Krause-Jensen, TM Greve: European seagrasses: an introduction to monitoring and management. EU project Monitoring and Managing of European Seagrasses (online) (PDF; 8.0 MB)
- ↑ a b c d Ronald C. Phillips, Ernani G. Menez: Seagrasses. 1988, Number 34, Smithsonian Contributions to the Marine Sciences, p. 46, (online)
- ↑ a b c d e f Salvador Talavera Lozano: Posidoniaceae In: Flora Iberica. Vol. 17, (online) (PDF; 370 kB)
- ↑ a b J. Ott: Oceanography: Introduction to the geography and biology of the oceans. Ulmer, Stuttgart 1988, pp. 251-261.
- ↑ Seaweed: The oldest living thing in the world? to: science.orf.at , February 10, 2012 with reference to doi: 10.1371 / journal.pone.0030454 "... Extreme Life Span ..." in Open-Access Journal PLoS One
- ↑ AWD Larkum, RJ Orth, CM Duarte: Seagrasses: Biology, ecology and conservation. Springer, Dordrecht 2006.
- ↑ Chapter 6: The role of oceans as carbon sinks. In: C. Nellemann, E. Corcoran, CM Duarte, L. Valdés, C. De Young, L. Fonseca, G. Grimsditch (Editor): Blue Carbon. A Rapid Response Assessment. United Nations Environment Program, GRID-Arendal 2009, ISBN 978-82-7701-060-1 , Table 1, p. 39. (online)
- ↑ Ecological natural insulation from the sea. on: energie-experten.org
- ^ Núria Marbà, Carlos M. Duarte: Mediterranean warming triggers seagrass (Posidonia oceanica) shoot mortality . In: Global Change Biology . tape 16 , no. 8 , August 2010, doi : 10.1111 / j.1365-2486.2009.02130.x .
- ↑ Gabriel Jordà, Núria Marbà, Carlos M. Duarte: Mediterranean seagrass vulnerable to regional climate warming . In: Nature Climate Change . May 2012, doi : 10.1038 / nclimate1533 .
- ↑ "El fondeo puede acabar en tres años con la posidonia de Formentera". In: Diario de Ibiza from September 14 to 16 and October 8, 2011
Web links
- Stephanie Eichler: Threatened oases under water. In: Der Tagesspiegel. Knowledge. Retrieved October 9, 2011.
- Superlative seagrass meadow
- Posidonia oceanica inthe IUCN 2013 Red List of Threatened Species . Posted by: Pergent, G., Semroud, R., Djellouli, A., Langar, H. & Duarte, C., 2009. Retrieved January 9, 2014.