Quote:
Originally Posted by fish.freak
Tom, I neither reject or accept the claim on basis of ignorance. I am working my way through the abstracts and happened upon this: Corals exposed to Sargassum grew significantly more slowly (80% reduction) than controls, but this effect was absent when corals were caged to prevent physical contact with macroalgae.
Wouldn't this negate inhibition via macro in sump?
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For the
Sargassum spp. and that particular coral IN THE OPEN SEA WHERE DILUTION OF THE ALLELOPATHIC SUBSTANCES WOULD BE ALMOST INFINITE, it requires direct contact. As there are eight different mechanisms employed by algae as allelopathic competitors, it will sometimes depend on the coral and the algae.
However, in a closed system where there are high population densities of the algae and the coral when compared to the sea (very few locations in the ocean have densities where algae tke up 25% of the total volume of a region), and in 185 or so USG of recirculated water, substances like this tend to accumulate, even with good skimming and carbon, to many MANY times the concentration of that found in the ocean...
And the corals often have triggering allelopathic substances that make the algae release the defenses they have (in many many times the concentration of that found in the ocean as well...)
We will find that instances of this type of competition can be multiplied many times both in terms of concentrations of triggers or toxins and in consequences of the releases of allelopathic toxins when we talk of closed systems nd the accumulations of these substances.
I'm not telling you to pull the stuff. If you feel that exporting via algal capture and harvest is in the best interest of your system of
stony corals, go ahead, as most aquarists have bigger issues with exporting phosphate and/or nitrate than worrying about how their stony
coral specimens are going to deal with natural competition. However, you need to find a way to deal with the accumulations of the allelopathic products of the algae if you do. Not so much an issue with octocorals or all fish only systems, but for the stonies, you've been informed... it can be the difference between surviving and thriving.
More info for an in-depth read and overview:
Algae: An introduction to Phycology, C. Van Den Hoek, D.G. Mann, and H. M. Jahns,Cambridge Univ Press, 1995, ISBN: 0-521-31687-1.
The Physiological Ecology of Seaweeds, Duncan, Mary Jo, Cambridge University Press, 1985. (sorry, ISBN is damaged on the outside of this book)
Algae, Graham, Linda E. and Wilcox, Lee W., Prentice Hall, 2000,ISBN 0-13-660333-5.
), maybe he'll post the link for it, or pull some exerpts from it for us. 
