Halimeda macroalgae causes coral disease ?

[mastou]

I have been reading about the Halimeda algae and at first it seemed like a good macroalgae, easy to control, beautiful coloration, interesting defence mechanism (movement of it's chloroplasts) etc.
However in my search for information I came across a publication
Ecology letters October 2004 - Vol. 7 Issue 10 Page 919-924 suggesting:

An algae often grown in the reef tank has been found to cause a disease in some forms of coral. According to new research by published in next month's issue of the journal Ecology Letters, direct contact with the macroalgae Halimeda opuntia can trigger a virulent disease called white plague type II. Nugues, Smith, Hooidonk, Seabra and Bak, claim that white plague type II, which has caused widespread deaths in Caribbean corals, often occurs simultaneously with heavy growths of macroalgae. To test their hypothesis, the scientists exposed the hard coral Montastraea faveolata to the algae. Some of those exposed to H. opuntia developed the disease, while those that were unexposed did not. The disease is believed to be caused by a bacterium called Aurantimonas coralicida. This was found to be present on the macroalgae, both near to, and far away from diseased corals, indicating that it acts as a reservoir for the disease. The team believes that macroalgae are responsible for many coral wipeouts and suggest controlling macroalgae in order to save corals from white plague. The algae is often sold as an ornamental macroalgae for the reef aquarium, however, on the basis of this research it may perhaps be wise to remove it from your aquarium now. For more details see the paper: Maggy M. Nugues, Garriet W. Smith, Ruben J. Hooidonk, Maria, I. Seabra, Rolf P. and M. Bak (2004) - Algal contact as a trigger for coral disease. Ecology Letters, Vol. 7.

Do any of you have additional information? and do you think Halimeda in aquariums also can provoke the coral disease (white plague type II)?

/Magnus

 

[Samala]

Hi Magnus, welcome to the forum. Very interesting topic you've presented, I'll be going through that article you posted. (Thanks for the reference!) Where did the quoted text appear? On another aquarium forum, an aquarium magazine, or something like that?

>Sarah

 

[mastou]

Oh year, I forgot the link to the quoted text it was from http://www.practicalfishkeeping.co.uk

Sorry about that

 

[coreno16]

suscribed. Very interresting topic, and im interrested as well as i have some in my tank.

 

[morphriz]

Hmm,
makes sense. A simple organism uses bacteria as it's weapon where more complex organisms, like corals, use mecanical or cemical weapons.
The big issue I suppose is if it's nutrient pollution, favoring algal growth, or raised temperature, stressing corals, that cause the outbreaks in the caribean. If it is nutrient pollution it's really a big problem if it's affecting reefs "already". I'd hate to see reefs die out in my lifetime.
//Mattias

 

[mastou]

What surprises me is that Halimeda, which is one of the prime reef builders or more correctly it's calcium carbonate skeleton is, should be a reservoir for the bacteria causing white plague and thereby be "bad news" for corals ! ?

Therefore it would of cause be very interesting to hear from any of you who have Halimeda in an aquarium along with stony corals.

By the way, if the bacteria causing white plague sits "on" the Halimeda algae it might not be a problem we'll see in the aquaria, or ?
/Magnus

 

[mastou]

Well just to keep this thread going now I found another publication suggesting:

ABSTRACT: Several studies have shown that the growth of macroalgae is reduced when in contact with corals, but very few have addressed the mechanisms involved. This study provides for the first time an explicative mechanism for the inhibition of algal growth by scleractinian corals. In experimental field contacts between 8 species of scleractinian corals and the green alga Halimeda opuntia, corals extruded their mesenterial filaments (MFs) onto the plant. In some coral species, this extrusion was followed by persistent discolouration of the contacting algal segments. Microscopic examination of these segments revealed migration of chloroplasts away from the surface of segments, as well as the presence of nematocysts from the MFs fired into the algal epidermis. There was a significant relationship between the extent of algal discolouration and both the occurrence and length of the MFs, potentially explaining differences among coral species in their ability to damage algal segments. MF extrusion also occurred in experimental contacts with 2 other species of macroalgae (Lobophora variegata and Dictyota sp.). The use of extruded MFs by scleractinian corals against macroalgae is similar to their aggressive behaviour against other scleractinian coral species. However, the ranking of competitive ability against H. opuntia (measured by the extent of algal discolouration) differed from that established in interspecific aggressions among corals. The great abundance and wide distribution of the species of corals and macroalgae used in this study, together with observations of MFs in natural interactions, suggest that the use of MFs is a common and widespread mechanism of interaction between corals and macroalgae. We conclude that coral-algal competition involves complex mechanisms and is therefore likely to represent a complex hierarchical structure, in which macroalgae are not always able to overgrow and kill corals.

Seems like it is one long fight between algae and corals, have any of you had any experience with either case (algae figthing corals or corals fighting algae)?

/Magnus

 

[morphriz]

Biological vs Chemical warfare. I don't know why people persist in finding UFOs. Grab some scuba gear and it's close contact of the first kind right away

This is interesting enough for me to consider a career in biology. I'd like to put up an experiment with different "fight" senarios in with different nutrient leves, different nutrient carriers, solved and particulate matter.

Man, might as well start Seagrass and Macro Addicts Anonymous right away!

 

[mastou]

<a href=showthread.php?s=&postid=7411125#post7411125 target=_blank>Originally posted</a> by morphriz
I'd like to put up an experiment with different "fight" senarios in with different nutrient leves, different nutrient carriers, solved and particulate matter.

Good idea, if you do please keep us posted

/Magnus