Candlestick algae

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Candlestick algae
Fragile candelabrum alga (Chara globularis)

Fragile candelabrum alga ( Chara globularis )

Systematics
without rank: Archaeplastida
without rank: Chloroplastida
without rank: Charophyta
without rank: Phragmoplastophyta
without rank: Streptophyta
without rank: Candlestick algae
Scientific name
Charophyceae
Rabenh.
Detail probably from Chara virgata; important determinants are the connection and the texture of the stipular wreath below the whorls. Also note the typically arranged reproductive organs
Gametangia in a monoecious candy algae; below the male antheridium , above the female oogon
Stiff-bristled candelabra ( Chara hispida )

The candelabrum algae (Charophyceae or Charales) are a phylogenetically primitive group of organisms of aquatic "plants" that are widespread worldwide . Poor algae are sometimes counted among the green algae , but they only have in common the assimilation pigments and reserve substances . Their habitus resembles rather higher flowering plants (especially the horn leaf , Ceratophyllum ). With their structure and their reproductive organs, candelabrum algae are an isolated group in the system of today's living things. From a phylogenetic point of view, they are considered sister taxonsof land plants ( Embryophyta ). The scientific name was derived from the Latin chara (= a certain tuber fruit with a bitter taste). Carl von Linné shaped this in 1763. They owe their German name to the arrangement of the whorl branches and the gametangia on them ; this is reminiscent of a multi-armed candlestick .

features

Depending on the species , the thallus, which is up to one meter long and anchored to the base with rhizoids, is divided into long internode cells and short nodal cells. In shape, candelabra are also reminiscent of horsetail : branches (radii) arranged in whorls grow at regular intervals on a vertical central axis . The male and female sexual organs, the gametangia , sit on these - in dioecious species they are separated on different "plants", in monoecious species the antheridia and oogonia are placed next to each other. Sexual reproduction takes place through oogamy , vegetative reproduction sometimes through the formation of root nodules. Oospores, the ripe oogonia, serve as persistence organs on the water sediment. In the genus Chara , the main and minor axes of the thallus are wrapped in stiffening binding threads; these are missing from the other species-rich genus Nitella . In some species, the whorls or the shoot axes are covered with small spines or "warts". Characteristics such as the number of binding threads in relation to the number of whorled branches (haplostich, diplostich, triplostich) and the position of spines on (tylacanth) or between the binding threads (aulacanth) serve to further morphological differentiation of the species. The so-called stipular wreath at the base of the whorls and the nature of the whorl branches (cell arrangement, end tip, etc.) can also provide information about the affiliation, as well as the position and shape of the gametangia. A determination is usually not possible without optical aids ( binoculars ).

Occurrence

Chandelier algae grow at the bottom of bodies of water with usually very clean, nutrient-poor, calcareous fresh water, and more rarely brackish water . These can be oligo- to mesotrophic clear water lakes or spring pots . Some Eurocean species also appear as pioneer vegetation in rainwater pools , ditches and newly created dredging ponds. Often they form large dominant populations of underwater lawns ("chara meadows"). These chandelier algae societies are treated as a separate plant-sociological class "Charetea fragilis" (Fukarek ex Krausch 1964), which in turn is subdivided into various orders, associations, and one-species societies.

Since they have no air-filled tissue, torn off parts of the shoot do not rise to the surface. It is possible that the occurrence of candelabrum algae in deeper waters is easily overlooked. In addition, with water depths of in extreme cases up to 60 meters, they reach submerged zones that “modern” vascular plants - such as pondweed plants , which can dive no more than seven meters - cannot be colonized.

Function in the water

Many Characeae are particularly represented in calcareous locations. Then they are typically covered with a rigid calcareous crust. This is due to the fact that candelabrum algae remove inorganic carbon compounds from the water during intensive photosynthesis . They intervene in a complex solution equilibrium, so that calcium carbonate is precipitated. Chandelier algae are thus effectively involved in the biogenic decalcification of hard water.

Systematics

The taxon Charophyceae was established by Gottlob Ludwig Rabenhorst in 1863 . The Charales were described in a work by Barthélemy Charles Joseph Dumortier in 1829 . Both taxa are considered identical today. According to AlgaeBase, the chandelier algae taxon is divided into five families and currently comprises 727 recent and 24 fossil species. All recent species belong to the Characeae family. (As of December 2015)

Genera and species

Underwater lawn made of chandelier algae ( Nitella sp.) In a shallow meadow pond
Chandelier algae ( Chara sp.) Form a white lime crust on a spring pond that dries on the surface in the air
Existence of common candy algae ( Chara vulgaris ) near the water surface of a clear pool (together with water knotweed )

Selection (here: all species occurring in Germany):

  • Foxtail chandelier algae ( Lamprothamnium J. Groves )
    • Hansen's chandelier alga ( Lamprothamnium hansenii (Sonder) Corillion )
    • Common chandelier alga ( Lamprothamnium papulosum (Wallroth) J. Groves )
    • Special foxtail candlestick alga ( Lamprothamnium sonderi Garniel )

Most species of chandelier algae are on the Red List of Endangered Species in Germany and other countries as endangered, endangered or even endangered species due to their preference for clean, nutrient-poor waters . The Chara vulgaris and Chara globularis as well as Nitella flexilis , which are widespread worldwide, are more common - with regional differences . These are pioneer species that quickly form larger populations, especially in newly formed bodies of water, but can also disappear again quite suddenly. Some other species also occur only very inconsistently in certain waters.

According to Annex I of the Habitats Directive of the European Union, “oligo- to mesotrophic calcareous still waters with benthic vegetation and black candy algae” are a particularly protected habitat type throughout Europe.

The genus Chara was from the section Phykologie the German Botanical Society for the algae of the year named 2012th

Web links

Commons : Candelabra  - Collection of images, videos and audio files

literature

  • Lexicon of Biology. Volume 2, Herder-Verlag, Freiburg 1984, ISBN 3-451-19642-5 .
  • R. Pott: The plant communities of Germany. UTB, Ulmer-Verlag, Stuttgart 1992, ISBN 3-8252-8067-5 .
  • H.-C. Vahle: Chandelier algae (Characeae) in Lower Saxony and Bremen. Spread, endangerment and protection. In: Information service for nature conservation in Lower Saxony. 10 (5), Hannover 1990, pp. 85-130.

Individual evidence

  1. ↑ K. van de Weyer, C. Schmidt, B. Kreimeier, D. Wassong: Identification key for the aquatic macrophytes (vascular plants, candelabrum algae and mosses) in Germany. Version 1.1, May 20, 2007; see. Cape. 5 "Chariden", p. 23ff. (PDF)
  2. ↑ Charales. In: MD Guiry, GM Guiry: AlgaeBase. National University of Ireland, Galway, last accessed December 28, 2015.
  3. ^ Working group Characeae in Germany: Preliminary checklist of the Characeae in Germany.
  4. ^ U. Raabe, K. van de Weyer: Chandelier algae (Characeae) in North Rhine-Westphalia. State Institute for Ecology, Land Management and Forests NRW (LÖBF), LÖBF-Announcement No. 4, 2002 (PDF)
  5. ↑ Phycology Section: Alga of the Year 2012: Chandelier alga Chara - threatened pioneer with a tendency to dominance . ( Memento of the original from April 12, 2012 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Press release, 2012. @1@ 2Template: Webachiv / IABot / www.dbg-phykologie.de

further reading

  • Heiko Korsch: The candelabrum algae (Characeae) of Saxony-Anhalt. , In: Series reports of the State Office for Environmental Protection Saxony-Anhalt , 2013/1, State Office for Environmental Protection Saxony-Anhalt, Halle (Saale), 2013, 85 pages. Full text PDF. (PDF, 6.48 MB, in German)