Golf rod

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Golf rod
Sargassum hystrix and Sargassum natans, illustration

Sargassum hystrix and Sargassum natans , illustration

Systematics
without rank: Sar
without rank: Stramenopiles (stramenopiles)
without rank: Brown algae (Phaeophyceae)
without rank: Fucales
Family : Sargassaceae
Genre : Golf rod
Scientific name
Sargassum
C. Agardh
free floating Sargassum in the Sargasso Sea
Sargassum muticum , an invasive species
Sargassum hystrix
Sargassum incisifolium
Sargassum hornschuchii , illustration

The golf rods ( Sargassum ) are an extremely species-rich genus of brown algae . They occur firmly - some species also swim freely - in warmer seas around the world.

description

shape

The size of the algae varies between 10 centimeters and more than 2 meters; specimens up to 16 meters in size have rarely been observed. From a disc-shaped or conical rhizoid arise one or a few pedicels to flattened stems ( cauloids ), which can be between one and 20 centimeters long. Every year these shoot side shoots that are 10 cm to a good 2 meters long and are thrown off at the end of the growing season. The primary branches are two-line or whorled on the cauloid, are pedicel-round, triangular or flattened and two or three-line or whorled.

The lower ( proximal ) side branches can in turn be branched or unbranched and are often leaf-shaped, but at least flattened, and (1–) 3–15 (–25) mm wide; if leaf-shaped ( phylloids ), they can be entire or toothed .

Most species form swim bladders ( pneumatocysts ), which can take the place of leaflets or sit in the armpits of the phylloids. These are egg-shaped to almost spherical and can be pointed and / or stalked.

Reproduction

The golf rods can be mono or dioecious , with segregated or hermaphroditic receptacula , which are formed in the axils by side branches of the first or second order (phylloids or pinnacles). They are usually in branched clusters, rarely individually. The conceptacula on its surface mature from bottom to top, with the receptaculum continuing to grow at the top. The receptacula can be round or flattened with a smooth, warty or prickly surface.

anatomy

The Cauloide and its branches consist of a cord made of elongated (in the center, however, isodiametric) cells derived from a plastid containing Meristoderm is surrounded. Linear growth is based on a three-edged apical cell , which is sunk into the shoot tip.

Occurrence

The golf rods are widespread worldwide in the tropical and warmer seas. Most species settle firmly off the coasts ( benthic ) (occasionally torn branches can drift in the sea). Along the coast they form Sargassum - "forests" ( kelp forest ), which offer a special habitat for small crabs, worms and other marine animals. It is assumed that a considerable part of the primary production of biomass in these algae forests.

Since 2011 there has been an increased occurrence of the Sargassum seaweed in the Atlantic, which is growing into a real plague and in 2018 some islands declared a state of emergency. In 2019 the brown algae carpet, referred to by researchers as the “Great Atlantic Sargassum Belt”, reached its maximum length to date. It stretches from West Africa to the Caribbean and consists of an estimated 20 million tons of seaweed. The cause is suspected to be over-fertilization and the deforestation of the Amazon rainforests.

The genus also includes two purely pelagic or planktonic species ( Sargassum natans and Sargassum fluitans ); these float freely in surface water, for example in the Sargassosee , which is named after the Sargassum . Their reproduction takes place only vegetatively through the disintegration of the thallus .

Systematics

The genus Sargassum was established by Carl Adolph Agardh in 1820 (in: Species algarum , volume 1, p. 1). Type species of the genus is Sargassum bacciferum (Turner) C. Agardh , which today is considered to be of the same species as Sargassum natans (Linnaeus) Gaillon .

According to Strasburger, the genus includes about 250 species; In the Algaebase database even 359 species names are accepted.

Types (selection)

  • Sargassum acinarium (Linnaeus) Setchell: in the warm and temperate eastern Atlantic (Canary Islands, West Africa), the Mediterranean, the Caribbean and the Indian Ocean
  • Sargassum bermudense Grunow: in the Caribbean
  • Sargassum dentifolium (Turner) C.Agardh: in the Indian Ocean (Persian Gulf, Red Sea, off Somalia)
  • Sargassum desfontainesii (Turner) C.Agardh: in the warm and temperate eastern Atlantic (Azores, Madeira, Canaries, Morocco)
  • Sargassum elegans Suhr: in the Southeast Atlantic (South Africa) and Indian Ocean (South Africa, Mozambique)
  • Sargassum fissifolium (Mertens) C.Agardh: in the warm and temperate eastern Atlantic (Canary Islands) and Australia
  • Sargassum fluitans (Børgesen) Børgesen: in the Caribbean and in the Western Pacific (Philippines)
  • Sargassum grevillei J.Agardh: in the Indo-Pacific (Indonesia, India, Thailand, Malaysia)
  • Sargassum ilicifolium (Turner) C. Agardh: in the Indo-Pacific, Fiji Islands, Australia and the Indian Ocean.
  • Sargassum incisifolium (Turner) C. Agardh: in the Indian Ocean and Southeast Atlantic (South Africa)
  • Sargassum muticum (Yendo) Fensholt: originally native to Japan, highly invasive , now introduced in large parts of the Northeast Atlantic (also in the North Sea), the Mediterranean and the North Pacific.
  • Sargassum natans (L.) Gaillon
  • Sargassum oligocystum Montagne: in the Northwest Pacific, Indo-Pacific, Pacific Islands and Australia
  • Sargassum platycarpum Montagne: in the warm eastern Atlantic (Canary Islands, Cape Verde), in the Caribbean and off Brazil
  • Sargassum polyceratium Montagne: in the Caribbean, in the Southwest Atlantic (Brazil) and Western Pacific (Philippines)
  • Sargassum tenerrimum J.Agardh: in the Northwest Pacific, Indian Ocean, Indo-Pacific and Australia
  • Sargassum vulgare C. Agardh: widespread in the Northeast Atlantic (Portugal, Spain to the Canary Islands), Mediterranean, Caribbean, Southeast Atlantic (West Africa), West Pacific (Philippines) and Indian Ocean

literature

Individual evidence

  1. ↑ Michael Guiry: The Seaweed Site: information on marine algae: Sargassum muticum , accessed June 5, 2018.
  2. ↑ a b c M.D. Guiry, GM Guiry: Sargassum C. Agardh, 1820 in: AlgaeBase. World-wide electronic publication, National University of Ireland, Galway, 2018. http://www.algaebase.org , accessed June 5, 2018.
  3. ↑ Christoph von Eichhorn: An algae carpet runs through the Atlantic , Süddeutsche Zeitung of July 4, 2019, accessed on July 8, 2019
  4. ↑ Sitte et al .: Textbook of Botany, see literature

Web links

Commons : Golftange ( Sargassum )  - Collection of images, videos and audio files
 Wikispecies: Sargassum  - Species Directory