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* Because corals have a large area to volume ratio, the algae on the corals are able to absorb a lot of light for photosynthesis, given ideal conditions.<ref name= "Venn" />
* Because corals have a large area to volume ratio, the algae on the corals are able to absorb a lot of light for photosynthesis, given ideal conditions.<ref name= "Venn" />
* Over 700 species of coral have been found to be in symbiosis with dinoflagellate algae.<ref name= "Yellowlees" />
* Over 700 species of coral have been found to be in symbiosis with dinoflagellate algae.<ref name= "Yellowlees" />
=== Subcellular Arrangement (Yellowlees 682) ===
*Subcellular arrangement of the coral-algae mutualistic relationship<ref name= "Yellowlees" />:
**“The dinoflagellate cell contents are surrounded by the algal plasma membrane and cell wall; this is in turn surrounded by multiple-layer host-derived membrane complex (the symbiosome), the coral endodermal cell and finally the host plasma membrane. This multi membrane architecture necessitates that metabolites that pass between the alga and host must pass through multiple cell membranes.
**[[File: Subcellular.png]]
***The contents of the algae cell are surrounded by the algae's plasma membrane and cell wall.
***Outside the cell wall is the symbiosome, which is a multiple-layer membrane complex that is derived from the host coral.
***The symbiosome is surrounded by the coral's endodermal cell and then the coral's plasma membrane.
***This multi-membrane structure means that the substances shared between the two organisms pass through multiple cell membranes.
== Relationship ==
== Relationship ==
=== Autotroph-Heterotroph (Saffo) ===
* The relationship between the coral and the algae is considered an autotroph-heterotroph mutualistic relationship. The algae produces its own food from sunlight and inorganic compounds, so it is an autotroph. The heterotrophic coral gets its food from the algae.<ref name= "Saffo" />
* “The alga requires nutrients that are derived from the host or from the environment surrounding the host, and the host acquires photosynthetic products from the autotrophic alga” (Yellowlees 680)
* The relationship between the coral and the algae is difficult to study because the mutual benefit occurs when the coral and the algae are together. The benefits of the relationship to each organism do not occur when the two are separated.<ref name= "Yellowlees" />
* because mutual benefit occurs when the coral and the alga are together, studying the benefits in action is difficult (Yellowlees 680)
* The algae requires nutrients that are derived from the host coral and from the environment that surrounds the coral, and the coral gets the products produced by the photosynthetic autotrophic algae.<ref name= "Yellowlees" />
=== Benefits to Corals: ===
=== Benefits to Corals: ===
* dinoflagellates produce 90% of the carbon that corals need through photosynthesis (Saffo)
* Through photosynthesis, the algal dinoflagellates produce 90% of the carbon that corals need for calcification. <ref name= "Saffo" />
** “In some coral species, much of the photosynthetic carbon is allocated to mucus, which is produced in copious amounts and is important in feeding and protection from mechanical damage and pathogens” (Venn 1074)
** Some coral species use the carbon from the algae to produce mucus. This mucus is important in feeding and in protection from mechanical damage and pathogens. <ref name= "Venn" />
** also remove respiratory carbon dioxide from the corals to use in photosynthesis (Yellowlees 680)
* The dinoflagellate algae release glycerol, sugars, organic acids, and amino acids. <ref name= "Venn" />
* dinoflagellates release glycerol, sugars, organic acids, and amino acids (Venn 1073)
** These substances are all "mobile compounds, which are compounds that are translocated to the animal tissues. ref name= "Venn" />
** these are all “mobile” compounds that are “compounds translocated to the animal tissues” (Venn 1072)
* Algae enhances the growth of the calcium carbonate coral skeleton, which gives the coral stability for its health as well as its physical architecture. <ref name= "Saffo" />
* dinoflagellates enhance growth of coral skeleton, giving it stability for health and “physical architecture” (Saffo)
* When the algae leaves the coral because of damaging environment conditions, otherwise known as coral bleaching, the corals suffer from the lack of support from the algae.<ref name= "Saffo" />
importance seen in “coral bleaching” - corals often die when dinoflagellates leave, causing the coral to turn white (Saffo)
** Impacts of bleaching include reduced growth and reproduction, increased susceptibility to disease and mechanical damage, and occasionally death of the coral. <ref name= "Venn" />
** “impacts of bleaching included reduced growth and reproduction, increased susceptibility to disease and mechanical damage, and occasionally death of the host” (Venn 1074)
=== Benefits to Algae: ===
=== Benefits to Alga: ===
* Corals help transport carbon dioxide from the surrounding seawater to the photosynthetic dinoflagellate algae. The algae needs the carbon dioxide in order to complete photosynthesis. <ref name= "Yellowlees" />
* corals help transport carbon from the surrounding seawater to the photysnethic dinoflagellates (Yellowlees 683)
** The coral has an enzyme that acidifies the boundary layer to convert carbon to carbon dioxide. This carbon dioxide diffuses into the host coral. It is trapped by conversion to bicarbonate and is then transported to the symbiosome of the algae. <ref name= "Yellowlees" />
** The host has an enzyme that acidifies the boundary layer to convert carbon dioxide. “This CO2 subsequently diffuses into the host where it is trapped by conversion to bicarbonate and is then transported to the symbiosome by an unknown pathway.” (Yellowlees 683)
* Corals provide the algae with a habitat.
* corals provide alga with habitat
* It is important to remember that the benefits to each organism of the relationship are difficult to determine as the benefits only occur while the relationship is occurring.
* again, hard to determine
== Conclusion==  
== Conclusion==  



Revision as of 10:56, 15 April 2015

Mutualism

A form of symbiosis that provides an obvious benefit to both the symbiont and the host. [1]

Background

  • Reef-building corals, in partnership with their algae symbionts, have been on Earth for at least 200 million years.[2]

Definition

  • Mutualism is a symbiotic relationship in which both the host organism and the symbiont benefit. However, the coral and algae mutualistic relationship is a little more complicated than the definition because the effects on the symbiotic algae are less clear than the effects on the hosts. [2]
    • The mutualistic relationship has clear benefits for the reef-building corals. However, the benefits for the photosynthetic dinoflagellates in the corals, Symbiodinium, are less clear. [3]
    • It is important to remember that the conditions for a healthy relationship between the coral and the algae have fairly strict boundaries as far as water temperature, ocean acidity, and amount of sunlight.
    • Because the coral-algae mutualistic relationship is dependent on a variety of factors, it is difficult to define a clear benefit for the symbiotic algae. The relationship can be a "shifting continuum" that can "under specific conditions shift into parasitism." [4]
      • As said previously, environment factors, such as increased temperature and dirty water, can strain the relationship between the coral and the algae. This strain can occasionall cause the costs of the relationship to outweigh the benefits.[2]

Biology

  • Corals are from the phyla Cnidaria [5]
  • Because corals have a large area to volume ratio, the algae on the corals are able to absorb a lot of light for photosynthesis, given ideal conditions.[5]
  • Over 700 species of coral have been found to be in symbiosis with dinoflagellate algae.[4]
  • Subcellular arrangement of the coral-algae mutualistic relationship[4]:
      • The contents of the algae cell are surrounded by the algae's plasma membrane and cell wall.
      • Outside the cell wall is the symbiosome, which is a multiple-layer membrane complex that is derived from the host coral.
      • The symbiosome is surrounded by the coral's endodermal cell and then the coral's plasma membrane.
      • This multi-membrane structure means that the substances shared between the two organisms pass through multiple cell membranes.

Relationship

  • The relationship between the coral and the algae is considered an autotroph-heterotroph mutualistic relationship. The algae produces its own food from sunlight and inorganic compounds, so it is an autotroph. The heterotrophic coral gets its food from the algae.[2]
  • The relationship between the coral and the algae is difficult to study because the mutual benefit occurs when the coral and the algae are together. The benefits of the relationship to each organism do not occur when the two are separated.[4]
  • The algae requires nutrients that are derived from the host coral and from the environment that surrounds the coral, and the coral gets the products produced by the photosynthetic autotrophic algae.[4]

Benefits to Corals:

  • Through photosynthesis, the algal dinoflagellates produce 90% of the carbon that corals need for calcification. [2]
    • Some coral species use the carbon from the algae to produce mucus. This mucus is important in feeding and in protection from mechanical damage and pathogens. [5]
  • The dinoflagellate algae release glycerol, sugars, organic acids, and amino acids. [5]
    • These substances are all "mobile compounds, which are compounds that are translocated to the animal tissues. ref name= "Venn" />
  • Algae enhances the growth of the calcium carbonate coral skeleton, which gives the coral stability for its health as well as its physical architecture. [2]
  • When the algae leaves the coral because of damaging environment conditions, otherwise known as coral bleaching, the corals suffer from the lack of support from the algae.[2]
    • Impacts of bleaching include reduced growth and reproduction, increased susceptibility to disease and mechanical damage, and occasionally death of the coral. [5]

Benefits to Algae:

  • Corals help transport carbon dioxide from the surrounding seawater to the photosynthetic dinoflagellate algae. The algae needs the carbon dioxide in order to complete photosynthesis. [4]
    • The coral has an enzyme that acidifies the boundary layer to convert carbon to carbon dioxide. This carbon dioxide diffuses into the host coral. It is trapped by conversion to bicarbonate and is then transported to the symbiosome of the algae. [4]
  • Corals provide the algae with a habitat.
  • It is important to remember that the benefits to each organism of the relationship are difficult to determine as the benefits only occur while the relationship is occurring.

Conclusion

References

  1. Sumich, James L. An Introduction to the Biology of Marine Life, Seventh Edition. WCB/McGraw Hill. 1999.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Saffo, Mary Beth. "Mutualistic Symbioses." ELS (n.d.): n. pag. - ELS. 15 July 2014. Web. 20 February 2015.
  3. Cite error: Invalid <ref> tag; no text was provided for refs named Saffo"
  4. 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Yellowlees, David, V. Rees, and William Leggat. "Metabolic Interactions between Algal Symbionts and Invertebrate Hosts." Plant, Cell, and Environment 31.5 (2008): 679-94. Wiley Online Library. John Wiley and Sons, 27 February 2008. Web. 20 February 2015.
  5. 5.0 5.1 5.2 5.3 5.4 Venn, A. A., J. E. Loram, and A. E. Douglas. "Photosynthetic Symbioses in Animals." Journal of Experimental Botany 59.5 (2007): 1069-080. Journal of Experimental Botany. Oxford Journals, 10 February 2008. Web. 20 February 2015.
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