Zooxanthellae

Zooxantela . They are endosymbiotic organisms of various marine animals and protists are dinoflagellate algae, although other types of algae, such as diatoms, can act equivalently. They are generally integrated by direct ingestion, and then multiply in the host tissues, providing it with various nutrients.

Summary

[ hide ]

  • 1 Relationship between Corals and Zooxanthellae
  • 2 Relationship with Zooxanthellae
  • 3 What is a plankton and a zooxanthellae?
  • 4 Sources

Relationship between Corals and Zooxanthellae

Coral reefs are relatively nutrient poor areas. The phosphate , nitrogen , iron and other essential nutrients are barely detectable in the clear water, which is thus essentially few organisms that develop in this ( Benson , 1984 ). To compensate for this lack of nutrients , many invertebrates have developed a symbiotic relationship with the algae they have in their tissues . Even the larvae of coral hermatypic already have these inherited zooxanthellae from their coloniesmother (Verón, 1986). The algae cells produce the energy that is used by the coral .

So also the coral produces ammonia as a by – product of its metabolism and the algae use it as an energy source. Some freshwater animals such as Hydra , Spongilla (lake sponge), and Paramecium (protozoan), contain a green algae known as Zoocblorella , while marine organisms generally contain golden-brown dinoflagellates of the genus Symbiodinium , commonly called zooxanthellae. (from Greek xanthos = yellowish brown color) ( Gordon , 1977). Therefore, contrary to popular belief , zooxanthellae are not green algae, but golden-colored dinoflagellates .

At one time it was thought that there was only a single zooxanthella species , Symbiodinium microadriaticum , but it has been shown that there are, in fact, several strains of these, some fast growing and others slower ( Blank and Trench , 1985 ; Trench , [ [File: 1979 ]]). By electrophoresis in gel , Blank and Trench ( 1987 ) found that the four bodies photosynthetic studied, each had its own distinct species Symbiodinium. the jellyfishof mangroves , Cassiopeia, incorporates Symbiodinium microadriaticum in their tissues, Montipora has S. kawagutii, the Symbiodinium goreauii was found in the anemone of the Atlantic “Heteractis” lucida, and Symbiodinium pilosum a zoantido very common in the Caribbean , Zoanthus sociatus. Therefore, the most appropriate would be to say that photosynthetic invertebrates contain Symbiodinium spp. instead of saying they have S. microadriaticum.

Zooxanthellae are found in most hard corals that are reef builders , but also in many Octocorals (soft corals), including some gorgonians, sea anemones, zoanthids, coralimorphs (mushroom corals), and tridachnic clams. Sponges and some sea squirts use different types of symbiotic algae, but their function is essentially the same as zooxanthellae ( Gordon , 1977 ). Zooxanthellae are found in the second layer of cells below the outer layer of coral tissue, the epidermis., in a proportion of one algae cell for each animal cell. They are important components of reef-building corals as they provide them with nutrients, eliminate metabolic wastes , and contribute to the production of calcium carbonate skeletons . Corals with zooxanthellae grow rapidly, as they can deposit calcium carbonate 2 to 3 times faster than those without zooxanthellae.

Coral zooxanthellae are brown , which is the best color to absorb blue light ( Benson , 1984 ). If you have ever dived in a tropical sea , or seen photos of these areas , you may have noticed that the water is very blue. This is due to the absorption of the longest wavelengths of light (red and yellow) in the first few meters of water. Therefore, it is the blue light that extends the farthest into the sea. Zooxanthellae have been adapted to make the most of blue light. Some pigments isolated from zooxanthellae, such as carotenoids and xanthophylls, all exhibit absorptionmaximum between 408 and 475 nm, the blue end of the spectrum ( Jeffrey and Haxo , 1968 ). On the other hand, chlorophyll c2 isolated from the zooxanthellae of tridachnic clams, likewise exhibits its maximum absorption in the zooxanthellae blue end of the spectrum ( Jeffrey and Shibata , 1969 ). Similar to land plants , seaweeds adapt to low light levels (for example, those found deeper or under overhangs) by increasing the amount of chlorophyll and secondary pigments in their chloroplasts , further improving plus its ability to use blue light (Benson , 1984 ).

Zooxanthellae use light energy to fix bicarbonate, a form of carbon dioxide, to carbohydrates through the process of photosynthesis. The carbohydrates released by zooxanthellae are in the form of glycerol and glucose, fatty acids and amino acids such as alanine and leucine are also produced . This process requires certain nutrients, mainly nitrogen and phosphorous. As a nitrogen source, zooxanthellae use ammonia produced by corals ( Barnes , 1974 ; Gordon , 1977 ). Nitrogen and phosphorus have been suggestedproduced by coral is the result of the metabolism of the small amounts of zooplankton that corals feed on ( Barnes , 1974 ; Johannes , 1970 ). However, both ammonium, nitrate, and phosphorous are easily absorbed by corals, and are then used by zooxanthellae ( D’elia , 1977 , Muscatine, and D’Elia , 1978).

The internal cycle of phosphorous and nitrogen in a variety of compounds also occurs between zooxanthellae and corals ( Johannes , 1970 ; Muscatine and Porter , 1977 ). The carbon used by zooxanthellae comes mainly from carbon dioxide released by the coral, not from external sources. Finally, coral also releases acetate to zooxanthellae, which use it to form fatty acids that serve to stabilize their chloroplasts ( Benson , 1984 ).

Zooxanthellae can transfer up to 98% of their photosynthetic products to corals. This is facilitated by the digestive enzymes produced by the corals that act on the cell walls of the algae. These enzymes cause zooxanthellae cell walls to “leak” their contents, allowing them to pass their photosynthetic products onto the coral. Amino acids produced by zooxanthellae are used by coral to make proteins , fatty acids are used to produce waxes and lipids , while carbohydrates provide energy for work and tissue growth ( Beason , 1984 ).

A recently described phenomenon of coral / zooxanthellae symbiosis occurs in a species of hard redwater deep sea coral, Leptoseris fragilis. This coral contains zooxanthellae, but it is very normal to find it between 110-120 m (365-400 ft), an uncommon depth for a photosynthetic coral. At this depth, the quality and intensity of light are not suitable for zooxanthellae. According to Schlichter and Fricke ( 1986 ), L. fragilisIt contains pigments that alter the wavelength of light, and in this way it can be used by zooxanthellae. In summary, using light energy, zooxanthellae convert carbon dioxide (from bicarbonate obtained from seawater and carbon dioxide produced by cellular respiration of coral tissues) into carbohydrates ( glycerol and glucose ), lipids, and amino acids . These products are transmitted to the tissue of the host animal, which subsequently provides a source of nitrogen (mainly ammonia) and phosphate to the algae.

Relationship with Zooxanthellae

An important feature of corals and other reef animals is their symbiotic relationship with algae called zooxanthellae. These are microscopic algae that live within the tissues of polyps.. As they are algae, they have a green pigment, chlorophyll, which allows them to synthesize their own food through the photosynthesis process. Coral polyps obtain essential substances for their growth from zooxanthellae and algae a suitable place to live. For this reason corals grow best under conditions of high transparency in water, mainly in flat waters, since this allows better penetration of sunlight, essential for zooxanthellae. When coral bleaching occurs, this is that they lose their color, what has happened is that the zooxanthellae are removed which reduces the growth rate of the coral, so necessary to maintain the structure of the reef. How deep light can penetrate water is an important factor in determining how deep we can find reefs growing in good health. In places with clear waters such as Mona Island and Culebra, live corals are found from the shallowest parts of the reef to depths of 150 feet.

What is a plankton and a zooxanthellae?

On coral issues , a polyp feeds on plankton; and a zooxanthellae is an algae that lives inside the polyp. Plankton helps polyps help the photosynthesis process that is necessary for zooxanthellae to stay alive. And zooxanthellae produces carbon dioxide and other raw materials necessary for polyps to sustain themselves. It is a mutual benefit between zooxanthellae and polyps and so that corals can exist.

 

Leave a Comment