A recently discovered parasitic bacterium causes disease and impaired growth in corals

AquaBiomics

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Hi everyone,

I'm posting to bring to your attention a fairly recent set of discoveries about a widespread coral pathogen.

This pathogen lives inside coral tissues, affects many species in the hobby, and causes diseases and reduced growth. The parasite can be transmitted by snail vectors and through the water. It occurs in about a third of corals in nature, and also occurs in hobbyist tanks.

I'm posting this here because it affects SPS and I think readers of this forum may be especially interested. [This came up in a discussion in another thread, and motivated me to do some additional reading about these recent discoveries. (thanks @reefwiser for first bringing this one to my attention, it has led to a lot of fun new reading.) ]

--

Microbiologists have recently discovered a parasitic bacterium that infects corals and other invertebrates. This is a member of the order Rickettsiales, most of which are parasites that can only survive inside the cells of their hosts. The order includes Wolbachia (a group of bacteria that occurs in the cells of most insects and nematodes) and several pathogens of human and livestock.

They've recently named this bacterium Aquarickettsia rohweri. Here I will summarize a few relevant facts about this recently described parasite that may interest keepers of SPS and other corals. There is obviously a lot that is still unknown about this bug, but here is what the research shows so far:
  • It occurs in about 1/3 of wild corals sampled worldwide.
  • It occurs in many genera that we keep as hobbyists, including Acropora, Montipora, Seriatopora, Stylophora, and Goniopora.
  • It also occurs in anemones (including Aiptasia, as if you needed another reason to hate Aiptasia!) and Palythoa
  • It causes White Band Disease in Acropora cervicornis.
  • The pathogen can be transmitted by coral-eating snails, which also serve as a reservoir for the bacterium.
  • The pathogen can also be transmitted through the water to injured corals. As someone who frags corals, this caught my attention.
  • (Most interestingly of all) the parasite normally makes up a small part of infected corals' microbiomes, but nitrate enrichment leads to a bloom of A. rohweri and impaired coral growth in infected corals.
  • Researchers hypothesize it directly steals ATP and amino acids from the host cells, sapping the host's energy.
References supporting these statements (open access peer reviewed journals):
Klinges et al. 2019 , Zaneveld et al. 2016 , Gignoux-Wolfsohn et al. 2012

Finally, is any of this relevant for us in the hobby? Well, I recently analyzed the microbiome of twenty hobbyist aquariums using similar methods as described in the 2016 reference above, and found this bacterium in 10% of tanks. Twenty aquariums is a small sample, but as the samples keep coming in we will learn more about its prevalence across hobbyist and aquaculture tanks. I don't think we've seen the last of it.

--

I speculate that this parasite which is so common in nature may contribute to the challenges of keeping freshly imported wild Acropora colonies.

And I wonder about possible treatments. Other members of the Rickettsiales respond well to some of the antibiotics marketed for managing fish diseases... I wouldnt want to treat every coral, but if I knew I had an infected coral I'd sure like to try it...

I'll be curious to hear your thoughts!
 

SeaDweller

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Interesting; more reasons to keep buying aquacultured frags from people and ones that are generations old. At this point, in my tanks life, i'm wary to add new stuff in.
 
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AquaBiomics

AquaBiomics

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Interesting; more reasons to keep buying aquacultured frags from people and ones that are generations old. At this point, in my tanks life, i'm wary to add new stuff in.
I share this expectation, that tank-grown frags from long established lines may have less A. rohweri than wild colonies. I bet you're right.

I just want to be clear that I don't have evidence of that yet - the studies focused on wild corals.
 

lexinverts

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Nice. Can you link the paper? Apologies if I missed it

 

redfishbluefish

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Most interesting! I haven't read the paper, but is this something that could be treated with antibiotics and part of your OT'ing of new corals?

A number of years ago I heard of folks treating their anemones with Cipro....now I wonder if it was because of this parasite???
 
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AquaBiomics

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So you think over time in our tanks, this bacteria is just dying off? But in nature it’s not? I will read this here soon, always love to read about stuff like this, it makes me feel smart :)
Since it lives in coral tissue, and leads to reduced growth in high nutrient conditions, I think its reasonable to imagine corals hosting this would be outcompeted, so that eventually most of the coral in a tank lacks the bug. Other invertebrates can serve as a reservoir for the bug, though, so maybe not. Maybe it'd stick around. Need more data on captive populations...
 

TDEcoral

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I've speculated for a long time that there was some kind of bacterial infection or other similar parasite causing all these unexplained STN issues that you see people posting about. I too have had this problem. Acros growing really well in the same tank with acros that are slowly receding from the base with no parameters out of whack to explain it.
 

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Hi everyone,

I'm posting to bring to your attention a fairly recent set of discoveries about a widespread coral pathogen.

This pathogen lives inside coral tissues, affects many species in the hobby, and causes diseases and reduced growth. The parasite can be transmitted by snail vectors and through the water. It occurs in about a third of corals in nature, and also occurs in hobbyist tanks.

I'm posting this here because it affects SPS and I think readers of this forum may be especially interested. [This came up in a discussion in another thread, and motivated me to do some additional reading about these recent discoveries. (thanks @reefwiser for first bringing this one to my attention, it has led to a lot of fun new reading.) ]

--

Microbiologists have recently discovered a parasitic bacterium that infects corals and other invertebrates. This is a member of the order Rickettsiales, most of which are parasites that can only survive inside the cells of their hosts. The order includes Wolbachia (a group of bacteria that occurs in the cells of most insects and nematodes) and several pathogens of human and livestock.

They've recently named this bacterium Aquarickettsia rohweri. Here I will summarize a few relevant facts about this recently described parasite that may interest keepers of SPS and other corals. There is obviously a lot that is still unknown about this bug, but here is what the research shows so far:
  • It occurs in about 1/3 of wild corals sampled worldwide.
  • It occurs in many genera that we keep as hobbyists, including Acropora, Montipora, Seriatopora, Stylophora, and Goniopora.
  • It also occurs in anemones (including Aiptasia, as if you needed another reason to hate Aiptasia!) and Palythoa
  • It causes White Band Disease in Acropora cervicornis.
  • The pathogen can be transmitted by coral-eating snails, which also serve as a reservoir for the bacterium.
  • The pathogen can also be transmitted through the water to injured corals. As someone who frags corals, this caught my attention.
  • (Most interestingly of all) the parasite normally makes up a small part of infected corals' microbiomes, but nitrate enrichment leads to a bloom of A. rohweri and impaired coral growth in infected corals.
  • Researchers hypothesize it directly steals ATP and amino acids from the host cells, sapping the host's energy.
References supporting these statements (open access peer reviewed journals):
Klinges et al. 2019 , Zaneveld et al. 2016 , Gignoux-Wolfsohn et al. 2012

Finally, is any of this relevant for us in the hobby? Well, I recently analyzed the microbiome of twenty hobbyist aquariums using similar methods as described in the 2016 reference above, and found this bacterium in 10% of tanks. Twenty aquariums is a small sample, but as the samples keep coming in we will learn more about its prevalence across hobbyist and aquaculture tanks. I don't think we've seen the last of it.

--

I speculate that this parasite which is so common in nature may contribute to the challenges of keeping freshly imported wild Acropora colonies.

And I wonder about possible treatments. Other members of the Rickettsiales respond well to some of the antibiotics marketed for managing fish diseases... I wouldnt want to treat every coral, but if I knew I had an infected coral I'd sure like to try it...

I'll be curious to hear your thoughts!

In Sweets studies, his belief that the use of ampicillin was effective in combating RTN without knowing what he was dealing with. It sounds like it could have been Rickettsiales, A. rohweri ?

On the findings of elevated N03, the question would be at what levels in our systems would be considered in the "red" zone?
 
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Flippers4pups

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The other question I have would be the use of probiotics in our systems. How would their use have a impact on these bacteria? Coral takes the probiotics into their tissue, does this make them more resilient to these bad bacteria?

Purely conjecture on my part with that question. I'm sure this hasn't been tested in a controlled setting yet.
 
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SeaDweller

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The other question I have would be the use of probiotics in our systems. How would their use have a impact on these bacteria? Coral takes the probiotics into their tissue, does this make them more resilient to these bad bacteria?

Purely conjecture on my part with that question. I'm sure this hasn't been tested in a controlled setting yet.
How would probiotics make them less susceptible to said bacteria though? You’re thinking the probiotic bacteria will now reside in their tissues and overtake the bad ones? Or the probiotic ones outcompete the bad ones? Or like a symbiotic relationship?
 

Gareth elliott

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How would probiotics make them less susceptible to said bacteria though? You’re thinking the probiotic bacteria will now reside in their tissues and overtake the bad ones? Or the probiotic ones outcompete the bad ones? Or like a symbiotic relationship?
allelopathy could also play a role, while there are not many studies on aquatic bacteria in this area; there is a lot on terrestrial species that inhabit plant roots. There is also an industrial application for herbicides to pay for these studies. But it is possible by adding Benign species you could limit pathogenic species. Poor example but a kin to how P. chrysogenum inhibits certain bacteria. All conjecture, as i couldn’t find one study involving allopathic chemicals for bacteria that didnt involve plants.
 

wareagle

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I've speculated for a long time that there was some kind of bacterial infection or other similar parasite causing all these unexplained STN issues that you see people posting about. I too have had this problem. Acros growing really well in the same tank with acros that are slowly receding from the base with no parameters out of whack to explain it.
There are actually a bunch of bacteria that can infect coral, vibrio is a common one that can cause paling and STN, it lives on the tissue, but attacks the zoox.


Vibrio likes sugar/glucose/sucrose, and you can see in this thread on using sugar for carbon dosing that people reported with corals expelling their zoox.

It would be nice if they find any of these bacteria and experiment with chemiclean to see if it kills them since chemiclean is something we can get our hands on that seems to take out some bacteria.
 

wareagle

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Is there anyway you could expose them to chemiclean, or some other anti bacterial medication we're allowed to buy as hobbyist?
 

GlassMunky

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Most interesting! I haven't read the paper, but is this something that could be treated with antibiotics and part of your OT'ing of new corals?

A number of years ago I heard of folks treating their anemones with Cipro....now I wonder if it was because of this parasite???
Using cipro on anemones is still common practice to this day. I wouldn’t get a carpet without having antibiotics on hand
 

GlassMunky

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Is there anyway you could expose them to chemiclean, or some other anti bacterial medication we're allowed to buy as hobbyist?
Chemiclean is not an antibacterial I don’t believe.
You also must be in Canada to be saying that you don’t have access to meds, which I do feel bad for you guys about. :(
 

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