Aegagropila linnaei

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Aegagropila linnaei
Aegagropila linnaei

Aegagropila linnaei

Systematics
without rank: Chlorophyta
without rank: Ulvophyceae
without rank: Cladophorales
without rank: Cladophoraceae
Genre : Aegagropila
Type : Aegagropila linnaei
Scientific name
Aegagropila linnaei
( Kützing 1843)

The algae Aegagropila linnaei is a thread-like freshwater green alga that occurs in three growth forms: as a lawn , as a tuft or as a free-floating ball . It occurs in winterly icing lakes all over the northern hemisphere. Natural occurrences are known from Austria , Iceland , Estonia , Ukraine and Japan .

The spherical shape of this alga is also called Marimo or algae ball . In this form it is a popular aquarium plant.

Synonyms are Cladophora aegagropila , Conferva aegagropila Linné, Cladophora linnaei Kützing or Cladophora sauteri Nees.

Names

The spherical shape of Aegagropila linnaei is also known as "Mooskugel", "Algakugel" and "Seeknödel". In English it is called "Cladophora-ball" or "lake ball". In Japan it is called "Marimo" ( Japanese 毬 藻 ).

The plant was named Marimo by the Japanese botanist Kawakami Tatsuhiko ( 川 上 龍 彦 ) in 1898. Mari is a jumping toy ball. Mo is a collective term for plants that grow in water. The name of the native Ainu is torasampe ( to = lake, rasampe = monster) or tokarip ( kari = move in a circle, p = object suffix or karip = sphere).

In Iceland, the fishermen on Lake Mývatn gave the balls the name kúluskítur ( kúla = ball. Skítur = any kind of weed that gets caught in the fishing nets).

classification

Marimo ball

The moss balls were first detected in 1820 by Anton Sauter in the Irrsee in Austria. The genus Aegagropila was created by FT Kützing (1843) with this species under the name A. linnaei as a reference species , with reference to its formation of spherical aggregations . All species were classified in the subgenus Aegagropila of the genus Cladophora by the same author in 1849 . A. linnaei was therefore named Cladophora aegagropila (L.) Rabenhorst and Cl. sauteri (Nees ex Kütz.) Kütz. in the genus Cladophora. Extensive DNA analyzes in 2002 led to a return to the old name Aegagropila linnaei . The presence of chitin in the cell walls distinguishes this genus from Cladophora .

Growth forms

Drawing of the three growth forms: lawn, tuft and ball

There are three growth forms of Aegagropila linnaei:

  • as a lawn of densely growing threads on rocks,
  • as a tuft of flooded threads on pebbles and
  • as balls made of interwoven threads, floating freely in the water .

The algae tufts and tufts of algae growing on stone are also known as epilithic (from ancient Greek epi = on and lithos = stone).

The spherical shape is created when the wind and waves roll off the epilithic algae. These then grow freely floating in the water, radiating in all directions. When the wind and waves roll this floating structure back and forth, a uniformly curved structure in the form of a ball gradually emerges.

The balls float on the surface during the day and sink to the bottom at night. Up and down lift are controlled by photosynthesis and the circadian rhythm . The buoyancy comes from the oxygen produced during photosynthesis , which gets caught in the form of fine bubbles in the braid of the threads.

ecology

Drawing of a Marimo colony in Lake Mývatn

Marimo colonies in Akan Lake on Hokkaidō and in Mosquito Lake ( Mývatn ) in Iceland are some of the strangest plant communities on earth. Their existence depends on the adaptation of the species to weak lighting, combined with the dynamic interplay of wind-driven currents, the course of the lighting, the hydromorphology of the lake, the soil substrate and the sedimentation .

The growth rate of the algae ball depends on the supply of light and nutrients, on average it is about 5 mm per year. In the Akansee they are particularly large, up to 20–30 cm. There are dense colonies of around 12 cm spheres that form well-defined spots on the lake bed at depths of 2 to 2½ m. The colonies were discovered in 1897 and have since shrunk significantly. The round shape of the Marimo is mainly created by gentle waves or currents that occasionally turn the balls.

In addition, exposure to sunlight increases photosynthesis and the formation of oxygen bubbles, so that the algae pillows, at least in the aquarium, rise from the bottom of the water towards the surface of the water. When dusk falls, they slowly sink back to the ground. Balls floating freely in the water can be made by introducing small plastic floats, whereby the balls can be held on the surface and on the bottom depending on the time of day.

The moss balls are green all around, so that photosynthesis takes place regardless of the position of the balls. Inside, the ball is also green and has dormant chloroplasts that become active within hours if the ball breaks apart.

The waves also cleanse them of detritus . Since some colonies have 2 or even 3 layers of the balls on top of each other, the waves are needed to mix them up so that each ball regularly comes to light. The spherical shape has the smallest surface area in relation to the volume, which is not optimal for plants for photosynthesis. This limits the possible size of the balls. The natural reproduction of balls has hardly been researched. They could grow from clusters of algae growing on rocks in the littoral zone , or from broken balls (as in the case of Lake Akan or in breeding for the aquarium).

natural reserve

The rapidly shrinking population of the Mývatn is a particular problem. For reasons unknown, some of the main colonies have disappeared in recent years.

Great efforts are being made to preserve the algae balls at Lake Akan . This includes the annual three-day Marimo Festival, in which the Ainu play an important role. Because of their appealing shape, the balls also serve as illustrative material for education and training on environmentally conscious behavior. They have certain similarities to the earth in that they are green and round and have to rotate to get light from all sides. In Japan, Marimo is under nature protection and has been declared a natural treasure of Japan . Small balls that are sold as souvenirs are hand-rolled from the free flowing threads. The buyer is told that with good care the plant will make a wish come true. Both Lake Mývatn and Lake Akan are protected, the first as a nature reserve, the second as a national park .

Use in the aquarium hobby

Marimo ball in the aquarium

The first imports to Western Europe were made in the 1970s, only to almost disappear again afterwards. Algae balls have been increasingly offered in pet shops in Central Europe for several years. The demand may also be due to the increased keeping of freshwater shrimp , which coincides with the introduction. They prefer grazing the balls. However, the literature on these plants is still sparse.

In general, the algae balls thrive in cold water aquariums for several years. Their growth is very slow and is only a few millimeters per year. In tropical aquariums, where temperatures are constantly above 27 degrees, some aquarists report that the plant "falls apart".

Algae balls do not have any special lighting requirements. However, it is advantageous if they are turned occasionally or if they can roll freely on the ground. They are sensitive to the build-up of mulch and detritus . pH levels between 7 and 7.5 seem to suit them best.

In pet shops they are occasionally recommended as an effective remedy for nitrite and nitrate pollution . However, the plant itself does not contribute more to lowering these substances in the water than other plants do. However, it is certainly advantageous that bacteria can settle in the fine algae hairs that reduce these substances in the water. Filling an aquarium with these algae pillows, on the other hand, is neither a substitute for water filtering nor for a partial water change .

Because of their susceptibility to the build-up of mulch and detritus , they should not be kept together with bottoming fish. Catfish can use the balls to deposit their spawn . For owners of small shrimp species, such as the caridina multidentata , algae balls are an alternative to Java moss is that like overgrown in the aquarium and covers other plants. They search the fine algae hairs for detritus just as intensively as they do with Java moss.

Trivia

Japanese Marimo postage stamp
  • The Japanese Post issued a 55 yen stamp with a Marimo motif in 1956.
  • The asteroid (4494) Marimo was named after the algae.
  • Marimo is the name of a character from the manga series One Piece . There it is also a nickname of the character Lorenor Zorro.
  • In an episode of the anime series Sailor Moon , a monster named Akan appears, named after the Akan Lake in Japan, in which Marimo grow, and uses it as a weapon against his opponents.

literature

  • A. Einarsson, G. Stefánsdóttir, H. Jóhannesson, JS Ólafsson, GM Gíslason, I. Wakana, G. Gudbergsson, A. Gardarsson: The ecology of Lake Myvatn and the River Laxá: variation in space and time. In: Aquatic Ecology. 38, 2004, pp. 317-348.
  • T. Hanyuda, I. Wakana, S. Arai, K. Miyaji, Y. Watano, K. Ueda: Phylogenetic relationships within Cladophorales (Ulvophyceae, Chlorophyta) inferred from 18S rRNA gene sequences, with special reference to Aegagropila linnaei. In: J. Phycol. 38, 2002, pp. 564-571.
  • GS Jonsson: Photosynthesis and production of epilithic algal communities in Thingvallavatn. In: Oikos. 64, 1992, pp. 222-240.
  • S. Nagasawa, I. Wakana, M. Nagao: Mathematical characterization of photosynthetic and respiratory property regarding the size of Marimo's aggregation. In: Marimo Research. 3, 1994, pp. 16-25.
  • Y. Yokohama, M. Nagao, I. Wakana, T. Yoshida: Photosynthetic and respiratory activity in the inner part of spherical aggregation of “Marimo”. In: Marimo Research. 3, 1994, pp. 7-11.
  • T. Yoshida, M. Nagao, I. Wakana, Y. Yokohama: Photosynthetic and respiratory property in the large size spherical aggregations of “Marimo”. In: Marimo Research. 3, 1994, pp. 1-6.
  • T. Yoshida, T. Horiguchi, M. Nagao, I. Wakana, Y. Yokohama: Ultrastructural study of chloroplasts of inner layer cells of a spherical aggregation of “Marimo” (Chlorophyta) and structural changes seen in organelles after exposing to light. In: Marimo Research. 7, 1998, pp. 1-13.
  • I. Wakana: A bibliography relating to “Marimo” and their habitats. In: Marimo Research. 1, 1992, pp. 1-12.
  • Christel Kasselmann : aquarium plants. 2nd Edition. Ulmer Verlag, Stuttgart 1999, ISBN 3-8001-7454-5 , p. 448.

Web links

Commons : Aegagropila linnaei  - collection of images, videos and audio files

Individual evidence

  1. Antony N. Dodd et al .: Photosynthesis and circadian rhythms regulate the buoyancy of marimo lake balls. In: Current Biology Magazine 28. Elsevier, August 20, 2018, accessed August 26, 2018 .
  2. MPC