Primary causes of RTN STN and why can't it be stopped?

[porpoiseaquatics]

Until recently, I didn't really understand either of these terms. I've experienced both in recent times with some acros including the recently purchased frags from Reef Pets (pre-crash but not by much). RTN or rapid tissue necrosis and STN or slow tissue necrosis are, from what I can gather, much the same thing the exception being that one generally happens overnight (or within 24 hours) while the other could happen over days or even weeks.

If memory serves, from the readings, both are caused by a bacterial infection. However, I've found no discussions on how the bacteria moves from one coral to another. I presume that it's free floating in the water column. That being said, then it would seem to me that it could be stopped through UV but that doesn't appear to be the case. In fact, the only method of stopping it is to superglue it, basically encapsulating the bacteria so that it can't spread. Surely, there's a better way. Some corals can look healthy at lights out and be completely gone by lights on the next morning.

It's a very frustrating "disease". As of right now, it's attacked and wiped out half of my acro pack that I received from RP. My real concern is not for the frags but for my colonies and whether or not I can prevent it from attacking them.

Thoughts?

 

[davidinga]

It's never been pinned down as to a cause.

Lots of theories - lighting changes, bacteria, virus, stress, pH/Alk swings, contaminates, etc.


Fwiw my Reef Pets frag order is all still 100% healthy and entrusting the plugs.

 

[tonymission]

Jeff -- Did you pay close attention to ALK when you got the frags? I typically test every day and it's the only thing I'm overly concerned about. I would say that's a lot more likely than a bacterial infection. Unless alk swings cause that.

 

[sea atlanta]

RTN and STN are not illnesses, but instead symptoms. Just like coughing isn't an illness for us, but a symptom of what could be a slew of different illnesses.

 

[glxtrix]

I hate it when I cough my flesh off!

 

[indecloudzua]

perhaps the bacteria is becoming resistant to the sterilization effects of the uv light??some bacteria can be unaffected by large amounts of uv radiation..if STN and RTN are caused by a bacteria, perhaps its doing what the antibiotic resistant bacteria are doing these days as well..the only times i had RTN/STN were when my alk dropped out and when i had a bacterial infection on my fish which then seemed to affect and kill some of my sps..

 

[sea atlanta]

indecloudzua;985987 wrote: perhaps the bacteria is becoming resistant to the sterilization effects of the uv light??some bacteria can be unaffected by large amounts of uv radiation..if STN and RTN are caused by a bacteria, perhaps its doing what the antibiotic resistant bacteria are doing these days as well..the only times i had RTN/STN were when my alk dropped out and when i had a bacterial infection on my fish which then seemed to affect and kill some of my sps..

Id be interested in seeing more on this. Germicidal UVC disrupts/destroys the mitochondria in the cells. Im not understanding how anything could get "immune" to that. The UV spectrum may shift ofut of the germicidal wavelength, but that doesnt have anything to do with the bacteria. If you have any info on this, I'd appreciate seeing it.

 

[indecloudzua]

I'll look into finding some and ask some of the marine biologist in the lab at school. With evolution, life will always find a way to adapt and survive. All it takes is a mutation in one bacteria genome.

 

[sea atlanta]

indecloudzua;985991 wrote: I'll look into finding some and ask some of the marine biologist in the lab at school. With evolution, life will always find a way to adapt and survive. All it takes is a mutation in one bacteria genome.

Thanks I'd appreciate it. Im just not understanding the biology of it. Heavier cell walled structures and organisms would need a higher exposure to that UV light, but again, thats not evolution nor immunity. I just dont understand how something can become immune to UV destroying its DNA itself. I'd love the insight. THANKS!

 

[indecloudzua]

http://en.wikipedia.org/wiki/Deinococcus_radiodurans">Deinococcus radiodurans - Wikipedia, the free encyclopedia</a>

here's a quick search of a UV resistant bacteria..look at the ionizing-radiation resistance section. I guess its wrong to say that they have an immunity..just that it takes a very huge amount of radiation..it appears that even some cyanobacteria are pretty resistant to UV light..it also appears that some bacteria also have the ability to repair damaged DNA..ill ask some of the dr's what they think tho..this could be a good research topic for me..

 

[marquiseo]

Here is my input on RTN/STN:


RTN/STN occurs because of a fight or flight response. This happens at a cellular level for sps. The skin layer of the sps is a giant organ same as that of the human skin. When conditions for the sps aren't favorable, the animal can choose to fight the stressor and flight which the RTN/STN process.

IMO when you see STN, the cells are undergoing apoptosis and when you see RTN, the cells are undergoing necrosis. Super glue can be used to cover the cell and stop the signal from being sent to nearby cells to undergo apoptosis. This explains why super glue stops STN but nothing else really can except fix what is making the animal go through fight or flight.

 

[marquiseo]

I don't think it would be a bacteria issue as well. Bacterial infections are contagious and in water, it is waterborne. Those single-celled organisms can spread and reproduce on other similar organisms. So if one sps goes through RTN/STN then they all would unless the others are some how inoculated. There have been infinite cases where only 1 sps undergoes RTN/STN and the rest lives so that debunks bacteria.

Lighting, alk swings, stress, and water contamination are all causes of RTN/STN because they can promote unfavorable conditions.
An animal in unfavorable conditions have to adapt or move on. SPS can't move so adapting or death(either programmed death (apoptosis) or by the stress triggering un-programmed death(necrosis)) are the only choices .
Reproduction will only occur in favorable conditions.


I hope this helps.

 

[enderg60]

As per the cause, cant say. Ive seen both RTN/STN and thriving corals happen in systems ranging from pristine to how are you even keeping fish in there.

The only thing I can say for sure is fragging is usually the only way to stop it. I liken it to gangrene, once it starts whatever the cause it will just keep spreading.

 

[marquiseo]

In a tank, there are many conditions that we have no control over. What we may think to be a thriving condition may not be the same in every spot in your tank. A tank may be golden one day and not so good the next because of an internal or external factor. Gangrene is a form of necrosis. Yes, it is stopped by cutting the infected limb off from healthy flesh. Necrosis can be explosive and when that initiated cell lands or touches healthy tissue, it spreads like a wildfire similar to how RTN is on SPS. RTN occurs too fast for us to save it. STN, on the other hand, we can save.

 

[snowmansnow]

Every single time I've had the pleasure of RTN it has been traced back to an ALK issue of some sort... normally low alk IME

 

[sea atlanta]

indecloudzua;985996 wrote: http://en.wikipedia.org/wiki/Deinococcus_radiodurans">Deinococcus radiodurans - Wikipedia, the free encyclopedia</a>

here's a quick search of a UV resistant bacteria..look at the ionizing-radiation resistance section. I guess its wrong to say that they have an immunity..just that it takes a very huge amount of radiation..it appears that even some cyanobacteria are pretty resistant to UV light..it also appears that some bacteria also have the ability to repair damaged DNA..ill ask some of the dr's what they think tho..this could be a good research topic for me..[/QUOTE]

Yeah, thats quite a bit different than acquiring an immunity through evolution. Essentially this bacterium has a robust structure which makes penetration of the UVC waves complicated. And I highly highly highly doubt this organism is whats causing any issue. Vibrio sp. bacterium is the pathogen of choice in most cases.

 

[marquiseo]

SnowManSnow;986032 wrote: Every single time I've had the pleasure of RTN it has been traced back to an ALK issue of some sort... normally low alk IME

It is the most common stressor. Not many people have full control of their tank's ALK. I know I don't test it that often. I should though.

 

[acroholic]

I think RTN/STN is symptomatic of an issue like SEA stated, but there can probably be more than one reason for causing it. This is anecdotal of course, but I had STN/RTN in a 300 gallon SPS tank I had a couple years ago when the corals got very large and changed the flow pattern in the tank. Simply put, I think the pumps I was using for in-tank circulation stopped providing adequate flow as the colonies got large for adequate food and waste exchange. I switched to a different type pump and more of them, and the RTN/STN Stopped overnight like flipping a switch.

So what I am saying is I believe RTN/STN can be caused by something non-biological in origin, like lack of adequate water movement in the tank or alkalinity issues (chemical in origin) like was stated above, not necessarily a result of a direct bacterial infection. And I am sure there are many other causes, biological and non-biological in origin.

 

[porpoiseaquatics]

This has been a very good discussion and I appreciate all the input. Keep it going!!!!

 

[marquiseo]

A symptom is an indication of a disease or an apparent reaction. That doesn't give what causes it. RTN is not a symptom, it is an end-state. Once it reaches that stage, it's pretty much death of the cells. Symptoms would be paling, no growth, and browning. At those stages, it can be corrected or treated. There are always indications but we just don't notice them until its too late most of the time.