That is indeed a great article!
Thanks for posting!
I'll take advantage and post here an observation from the same article you posted:
"To be sure, the predatory bacteria, Desulfovibrio and Beggiatoa have been found to destroy the tissue of Platygyra exposed to chemical pollutants (Mitchell, Chett 1975), and theV. vulnificus found by Bingman and Dixon (1997) is hemolytic and capable of causing tissue necrosis. However, other potential pathogenic Vibrio species, such as V. alginolyticus and V. parahaemolyticus, are swarmers that are capable of rapid colonization and form often dominant bacterial aggregates in coral mucus, even in the most inhospitable high flow conditions (Ducklow, Mitchell 1979). Thus, the presence of potentially pathogenic Vibrios in the coral mucus may be viewed as a normal occurrence that does not ordinarily cause disease. The finding of V. vulnificus in RTN affected colonies d it may be significant in both etiology and pathology of certain cases of RTN. However, its presence is not unexpected, nor is it demostratably
causative for all cases."
It is clear to me that Eric considered a Vibrio pathogen, even though he suggested otherwise. There was no definitive/total exclusion of a pathogen in the article for RTN, I believe. The article was published more with the intent of a speculation on the subject, trying to find more hypothesis related to the subject. Witch is very welcome to the literature in finding out what was going on. I do believe that we shouldn't exclude other possibilities as well. It could be a combination of factors too.
The problem is that there are basically two (or much more?) hypothesis for the phenomenon and of course that if the scientists didn't figure out what RTN really is, who am I to say what that is? LOL!!! No, I'm not imposing at any level that I do know what causes RTN for sure, but only bringing what the literature expose to us, hobbyists.
So to answer your question, no I do not know if RTN is indeed caused by bacteria. Not with absolutely certainty.
I'm sorry if I gave the wrong impression of talking down to anyone here. That wasn't my intention at all. Sometimes discussions can sound like that, but that wasn't what I wanted. One could come to my side of the boat and perhaps also feel like that. It's just a discussion and that happens sometimes. But I apologize to anyone if they felt mistreated.
It's important to keep the respect among us.
I have a tremendous respect for Eric and in fact want to bring one of his quotes about the subject. Please read:
"Is it possible through shipping we are killing these bacterium. Once in our systems that particular bacteria may not be available.
Yes, and no. There is a lot of work to be done in this area, but if you look at the works which have been done, there are definitely some bacteria genera which are typical -
Vibrios and Psuedomonas are very common colonizers, and Ritchie, et. al., showed a trend from Psuedomonas to Vibrios when coral tissue becomes necrotic - Vibrios exploit that material better...Ducklow and Mitchell showed Vibrios (mostly V. alginolyticus and V. parahaemolyticus) to compose over
50% of the flora on healthy corals...others have found similar constituents....at least some species are "swarmers" and use their flagella to actively stay around coral mucus rather than being sort of "drifters"...
Obviously, the ability of the coral to change its mucus content and composition will influence those types that colonize to some degree....as well as the nutritional status of the coral and, hence, the composition of the mucus produced. Shipping plays its role in that mucus is not well flushed and becomes thick...bacteria in logarhythmic growth can quickly become problematic in that they affect coral respiration by their numbers....
if anything, shipping doesn't eliminate the bacteria but causes a dangerous amplification of their numbers. Over time, though, we may see the extermination of one species by substrate dominance and without access to potential recruits, yes, we might be eliminating some of these "normal" flora.
However, I don't think anyone has (or could) actually get into a repertoire of tanks to analyze the average numbers and types of bacteria available or present. Marine bacteriology is pretty cloaked in mystery yet...Most of the work has been towards those species which show a potential for human pathogenicity and identification of species is very complex and many species are unnamed/unreported. The studies of coral mucus bacteria usually identify only by genera or, sometimes, even less.
That is one of the hurdles we are trying to overcome in our RTN bacteria work...Rob Toonen, who has our RTN cultures in perma-storage, has talked to a lot of people, asking for help, and they mostly laugh at the implications...."Impossible," they intimate. We do have a protocol now, and you can do some work via selective platings and antibiotic sensitivity assays, as Jonathan and I did originally, but apparently amplification of DNA using restriction length fragment polymorphism is required for good results and that costs $$$. AH for an aquarium industry grant! LOL"
From:
http://www.reefs.org/library/article/e_borneman2.html
That article is from around 1997 (?). The book I suggested was first published on 2005, so could be that the information on the article you posted isn't current (?). There were many questions, and still are, to answer the phenomenon and I don't think there is really a firm way to look at it yet.
You can also find more info in the Delbeek & Sprung's 2005 book on page 137.
They talk about the bacteria
Vibrio coralliilyticus affecting
Pocillopora damicornis to support their observations on RTN in closed systems. Such observations were carefully made related to higher temperature (stress) and total tissue loss, in the RTN context. Reference was indicated to
Ben-Haim and Rosenberg, 2002; Ben-Haim et al 2003. So it was a more recent scientific study then the 1997 article from Eric.
I hope you could take that into consideration.
This is not to prove my point, but to consider other works with an open mind and respect of the subject. It is so easy to just close for eyes and believe in the stress alone. It's true that it would be practically impossible to isolate such bacteria from reef tanks, but it is important to have an open mind to the great possibility of the presence of a pathogen, in order to possibly isolate the affected colony and prevent further infections.
If the hobbyist doesn't take all that info into consideration he/she will obviously ignore a serious possibility of the cause IMO. That isn't responsible in my point of view. To spread the word that the possibility of a pathogen isn't considerable isn't responsible either. It shouldn't be that way. It's just a matter of considering it as a possibility. My first impression, and after discussion went further, was that nowadays people just look at RTN as a pure and obligated reflection of stress, totally excluding any possibility of pathogen (bacteria) to be present in the system. That was the originated argument, after my first suggestion in this thread (post #14).
So, my point really is not to remove the great possibility of a pathogen.
Again, you might know of many tanks, even large systems, that never had any RTN issues, even when stress cause by temperature was a fact. That could be one of the observations to help us understand the phenomenon.
This is great!
Hope other could join us with their own observations/articles as well!! :beer:
Grandis.
