Laminaria

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Laminaria
Palm wrack (Laminaria hyperborea), washed ashore near Heligoland

Palm wrack ( Laminaria hyperborea ), washed ashore near Heligoland

Systematics
without rank: Sar
without rank: Stramenopiles (stramenopiles)
without rank: Brown algae (Phaeophyceae)
without rank: Laminariales
Family : Laminariaceae
Genre : Laminaria
Scientific name
Laminaria
JV Lamouroux
Leaf change in fingertip ( Laminaria digitata )
Illustration from Koehler's medicinal plants

Laminaria is agenus of brown algae from the order Laminariales . The species form extensive kelp forests on the coasts of the North and South Atlantic and North Pacific. They areused economicallyto obtain alginate . In 2007, thePhycology Section of the German Botanical Society named the genus Laminaria the first alga of the year .

description

features

The Laminaria - Sporophyten are a meter tall, perennial seaweeds that can reach an age of two to 18 years. They are divided into an adhesive organ ( rhizoid ), a stem ( cauloid ) and a leaf-like surface ( phylloid ). The organ of attachment is usually branched, more rarely disc-shaped (in Laminaria solleidula and L. yezoensis ) or rhizome-like (in L. sinclairii and L. rodriguezii ). The stem, which is round or flattened in cross-section, can be filled with pith or hollow on the inside. In some species annual rings can be seen in the stem . The phylloid is either entire and unlapped (section Simplices), or it has a distinct central strand (section Fasciatae), or is incompletely divided into finger-like segments (section Digitatae). The leaf surface is usually smooth, sometimes with a bulging, blistered or puckered surface, and has neither a central rib nor longitudinal ribs.

Leaf change

The leaf area is renewed every year from the base. As early as winter, the reserve substances stored in the old leaves are shifted to the growth zone at the transition to the stem. With increasing light, a new phylloid grows there in spring, on which the previous year's leaf is initially still attached. In some species the old leaf is shed as a whole, in others it gradually degenerates at the ends.

Tissue types

Laminaria sporophytes have various differentiated tissues : a central medulla (absent in the adhesive organ), a parenchymatic cortex and the outer meristoderm , which is both photosynthetically active and also has the function of an educational tissue ( meristem ). Real conduction paths (sieve tubes) in which the photosynthetic products are transported run in the pith. In the cortex of the stem and phylloid, there are cross-linked mucous ducts , which in some species open into secretion cells on the surface.

Chromosome number

The number of chromosomes is n = 22 to n = 31.

Development cycle

Laminaria shows 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 both sides of the phylloid in irregular, darker spots ( sori ) , in which 32 mobile zoospores arise through meiosis . These have a single plastid and neither have an eye spot nor a swelling on the flagella.

The zoospores establish themselves and grow into microscopic haploid gametophytes , which consist of a few cells or branched cell threads. The formation of the gametes is triggered by blue light. Too high or too low temperatures, nutrient or iron deficiency, however, prevent the formation of gametes. The male gametophytes form tufts of colorless, unicellular antheridia at the ends of the branches , each of which releases a single two-flagged spermatozoid . In female gametophytes, each cell can develop into a unicellular oogonium and form a single egg cell (with rudimentary flagella residues). The egg cell initially adheres to the oogonium and is usually released in the first 30 minutes after dark. At the same time, the egg cells secrete the pheromone lamoxiren , which attracts the spermatozoids from the antheridia to the egg cells. 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 life cycle of Laminaria is strongly influenced by the seasons. The time of the strongest growth is spring. In contrast, the Sori emerge in most species in autumn and winter, triggered by the shorter day length and falling temperatures. Only a few species ( fingertrack = Laminaria digitata , L. ochroleuca and the short-lived L. rodriguezii and L. ephemera ) are fertile in summer.

ecology

Tang forest of fingertrack ( Laminaria digitata )

The Laminaria TYPES have an important function in the ecosystem of Tangwälder because they offer many kinds of algae , animals and micro-organisms a habitat. Some of the microorganisms cause algae diseases and damage the laminariums, others protect the surface against rot or toxins or have a growth-promoting effect. Some microscopic algae live as endophytes within the laminar sporophytes, for example Laminariocolax and Laminarionema . Numerous epiphytic algae, especially red algae, often grow on the stems . Many epiphytic animals live on the laminariums, and the adhesive organ shows a special diversity of species. On the other hand, very high numbers of individuals were found on the stems, sometimes more than 7000 individuals can be found on a single Laminaria stalk. The phylloid is mainly covered by the moss animal Membranipora membranacea .

The microscopic laminaria gametophytes were also found as endophytes in red algae.

Among the species that feed on laminariums, the sea ​​urchins have the strongest influence. In particular, sea urchins of the genus Strongylocentrotus , which have reproduced en masse after overfishing, can devour entire kelp forests and completely destroy them, leaving only the bare bottom. Fish, snails and molluscs also feed on laminariums.

Occurrence

The genus Laminaria is mainly found in cool, temperate waters in the North Pacific , North Atlantic (also in the North Sea , Baltic Sea and Mediterranean ) and South Atlantic . It is absent in western South America, Australia, and Antarctica. Molecular genetic studies suggest that the species in the Atlantic and Pacific separated from one another 15 to 19 million years ago.

Laminaria grows on rocky subsoil in the sublittoral , where it forms extensive kelp forests . It can penetrate from the low water line to a sea depth in which at least 1% of the light is still available. Therefore, their maximum depth depends on the transparency of the water. In the murky water of the North Sea, the palm wrack ( Laminaria hyperborea ) is limited to a depth of 8 meters. Laminaria ochroleuca and Laminaria rodriguezii in the Mediterranean and Laminaria brasiliensis off the coast of Brazil reach the deepest occurrences up to 95 meters in clear water .

Systematics

Laminaria setchellii population at low tide

The genus Laminaria was established in 1813 by Jean Vincent Félix Lamouroux (In: Essai sur les genres de la famille des thalassiophytes non articulées . Annales du Muséum d'Histoire Naturelle, Paris 20: p. 40). As a type species was Laminaria digitata (Hudson) JVLamouroux determined (lectotype).

The genus Laminaria belongs to the Laminariaceae family within the order of the Laminariales . Guiry in Algaebase (2012) names 24 accepted species:

Numerous species that used to belong to Laminaria ( L. angustata , L. cichorioides , L. coriacea , L. dentigera , L. diabolica , L. groenlandica , L. japonica = Japanese leaf kelp , L. longicruris , L. longipedalis , L. longissima , L. ochotensis , L. religiosa , L. saccharina = sugar seaweed and L. yendoana ) were separated as a separate genus Saccharina in 2006 after molecular genetic studies .

ingredients

The Laminaria TYPES accumulate iodine to 30.000fachen the content in seawater. This makes them the most powerful iodine accumulators of all living beings. The iodine content of fingertip ( Laminaria digitata ) can be 0.25 to 5% of the dry matter.

The metals copper , manganese and iron are also enriched and used as trace elements for the activation of enzymes or for the transport of electrons during photosynthesis . The highest levels were found in the detention organ.

In the cell walls, the Phyko find colloidal alginate and fucoidan . As storage carbohydrates come laminaran and mannitol before.

use

Laminaria hyperborea on a postage stamp

Laminaria species are of great economic importance as a supplier of alginate . In Europe, mostly natural stocks are harvested for this purpose. In 2005 a production of 154,000 t is given for Norway ( Laminaria hyperborea ) and for France about 75,000 t (mainly Laminaria digitata ).

Other ingredients from laminariums are used in a variety of ways, for example for cosmetics , for food supplements , as remedies , as an additive to animal feed and as fertilizer . Since Laminaria is very absorbent and as a result expands when it absorbs liquids, it is used in gynecology in the form of a stick to aid in certain procedures, e.g. B. Curettages to open the cervix.

Laminariums can also be used for biological remediation ( bioremediation ) in the event of pollution or eutrophication , or to reduce the erosion of coasts. They can also be used as a bioreactor in molecular biotechnology or as a renewable raw material (fuel substitute).

swell

  • Michael D. Guiry, GM Guiry: Laminaria - In: Algaebase - World-wide electronic publication, National University of Ireland, Galway , accessed March 28, 2012 (sections description, tissue types, chromosome number, development, systematics)
  • Inka Bartsch, Christian Wiencke, Kai Bischof, Cornelia M. Buchholz, Bela H. Buck, Anja Eggert, Peter Feuerpfeil, Dieter Hanelt, Sabine Jacobsen, Rolf Karez, Ulf Karsten, Markus Molis, Michael Y. Roleda, Hendrik Schubert, Rhena Schumann , Klaus Valentin, Florian Weinberger & Jutta Wiese: The genus Laminaria sensu lato: recent insights and developments . In: European Journal of Phycology , 43: 1, 2008, pp. 1–86 doi: 10.1080 / 09670260701711376 (full text, sections ingredients, ecology, occurrence, use)

Individual evidence

  1. ^ Section Phycology of the German Botanical Society: Seaweed Laminaria is Alga of the Year 2007 . Press release 2007.
  2. ↑ a b 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.
  3. ↑ a b Inka Bartsch, Christian Wiencke, Kai Bischof, Cornelia M. Buchholz, Bela H. Buck, Anja Eggert, Peter Feuerpfeil, Dieter Hanelt, Sabine Jacobsen, Rolf Karez, Ulf Karsten, Markus Molis, Michael Y. Roleda, Hendrik Schubert , Rhena Schumann, Klaus Valentin, Florian Weinberger & Jutta Wiese: The genus Laminaria sensu lato: recent insights and developments . In: European Journal of Phycology , 43: 1, 2008, pp. 1–86 ( doi: 10.1080 / 09670260701711376 )
  4. ↑ Miriam S. Bernard, Martina Strittmatter, Pedro Murúa, Svenja Heesch, Ga Youn Cho: Diversity, biogeography and host specificity of kelp endophytes with a focus on the genera Laminarionema and Laminariocolax (Ectocarpales, Phaeophyceae) . In: European Journal of Phycology . tape 54 , no. 1 , January 2, 2019, ISSN  0967-0262 , p. 39–51 , doi : 10.1080 / 09670262.2018.1502816 .
  5. ↑ DJ Garbary, KY Kim, T. Klinger, D. Duggins: Red algae as hosts for endophytic kelp gametophytes . In: Marine Biology . tape 135 , no. 1 , October 1, 1999, ISSN  1432-1793 , p. 35-40 , doi : 10.1007 / s002270050598 .
  6. ↑ 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. 192-200.
  7. ^ WebMD: Laminaria. Retrieved September 9, 2016 .

Web links

Commons : Laminaria  - collection of images, videos and audio files