Palm wrack
| Palm wrack | ||||||||||||
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Palm wrack ( Laminaria hyperborea ) |
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| Scientific name | ||||||||||||
| Laminaria hyperborea | ||||||||||||
| ( Gunn. ) Foslie |
The palm wrack ( Laminaria hyperborea ) is a type of brown algae from the order of the Laminariales . It forms extensive kelp forests on the coasts of the north-east Atlantic and is also found in the North Sea and Baltic Sea. It is used economically to obtain alginate .
description
The palm kelp is a stately perennial kelp with a palm-like habit that can grow to be 2 to 3 meters long. The sporophyte is attached to the rocky subsoil with a strong claw-like, conical adhesive organ ( rhizoid ). Above this, the thallus is divided into a stalk ( cauloid ) and a leaf-like surface ( phylloid ) and has differentiated tissue.
The stem is round, stiff and has a rough, wrinkled surface that is often colonized by red algae . The length of the stem reaches 0.2 to 1.5 (rarely up to 2) m depending on the populated water depth. It consists of a layer of bark and a central body in which real conduction paths run and secondary growth in thickness can be seen through annual rings . The brown, leathery, coarse phylloid with a length of up to 1.5 m is divided into fingers and is characterized by a heart-shaped leaf base.
The palm kelp differs from the similar fingertip ( Laminaria digitata ) by its round, stiff, rough stem and the lighter leaf surface with a heart-shaped leaf base.
Leaf change
The palm wedge leaf is renewed every year. The reserve substances stored in the old leaves are transported to the growth zone as early as winter. With increasing light, a new phylloid grows from the leaf base in spring, on which the previous year's leaf still sits until the beginning of May. Then the old leaves are usually torn off in a storm and washed onto the beach in large quantities.
development
The palm wrack has a generation change with two very different generations. The visible seaweed is the diploid sporophyte . In autumn and winter, the tubular sporangia are formed on the phylloid in irregular, darker spots ( sori ). In each sporangium , 32 mobile zoospores arise through meiosis . These grow into the haploid gametophyte , which consists of microscopic, branched cell threads. At low temperatures (4 to 10 ° C) the egg cells and spermatozoids are formed here. After fertilization, the zygote settles and germinates into a young sporophyte. The young plants become fertile for the first time at two or three years of age .
The palm wrack can live up to 15 years.
ecology
The stalks of the palm wrack are often occupied by numerous epiphytic red algae , for example Palmaria palmata , Phycodrys rubens , Membranoptera alata , Ptilota gunneri and Cryptopleura ramosa . At greater depths, the thalli are often overgrown by bog animals ( Membranipora membranacea ).
With massive grazing by the green sea urchin Strongylocentrotus droebachiensis , the stocks of palm wrack can be completely pushed back. In the overgrazed areas, coralline crustal algae and sea urchins dominate for more than five years.
Occurrence
The palm wrack is found off the coast of the eastern North Atlantic from Iceland and Norway to Spain and the Canary Islands . It can also be found on suitable substrates in the North Sea and Baltic Sea , for example near Helgoland .
It inhabits the sublittoral and forms dense kelp forests on rocky ground . In the North Sea it grows in a depth of 1 to 4 m below the low water line as a closed stand, down to a maximum depth of 8 m it only occurs in gaps. In clear water, however, it can grow to a depth of 24 m and can penetrate to a depth of 32 m.
Systematics
The palm wedge was first described in 1766 by Johan Ernst Gunnerus under the name Fucus hyperboreus (In: Flora norvegica 34, Fig. 3, No. 61). Michael Heggelund Foslie placed the species in the genus Laminaria in 1884 (In: About the Laminariums of Norway . Christiania Videnskabers Selskabs Forhandlinger 14: p. 42).
Synonyms for Laminaria hyperborea (Gunnerus) Foslie are Fucus hyperboreus Gunnerus, Fucus scoparius Ström, Hafgygia cloustonii (Edmondston) Areschoug, Laminaria cloustonii Edmondston and Laminaria hyperborea f. compressa foslie.
Laminaria hyperborea belongs to the Laminariaceae family within the order of the Laminariales .
use
In the past, the seaweed washed up or harvested when the water was low was used as fertilizer . In the Middle Ages, the incineration of algae (kelp) was of economic importance in order to extract alkalis , which were needed for soap and glass production . Seaweed incineration later flourished again to produce iodine .
Today, palm kelp is an important supplier of alginate , which is used, for example, in the food, cosmetics, textile, rubber and paper industries. The main suppliers are Norway and Scotland . The harvest in Ireland has ended in recent years.
swell
- P. Kornmann, PH Sahling: Sea algae from Helgoland - Benthic green, brown and red algae. Biological Institute Helgoland, Hamburg 1983, ISSN 0017-9957 , pp. 144-149. (Sections description, leaf change, development, occurrence, ecology, use)
Individual evidence
- ^ A b c Ecological relationships UK Marine Special Areas of Conservation
- ↑ a b c Michael D. Guiry, GM Guiry: Laminaria hyperborea - In: Algaebase - World-wide electronic publication, National University of Ireland, Galway , accessed on March 28, 2012.
- ↑ a b Michael Guiry: The Seaweed Site: information on marine algae: Laminaria hyperborea , accessed on March 28, 2012.
- ↑ Wolfram Braune: Marine algae. A color guide to the common benthic green, brown and red algae of the world's oceans . Ruggell: Gantner, 2008, ISBN 978-3-906166-69-8 , pp. 196-197.
Web links
- Scinexx: algae sugar against arthritis? Polysaccharide from brown algae could stop cartilage breakdown in joints from August 24, 2017