Chytrid in caudates

Molch

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well, having some time on my hand today, I've been surfing reading up on chytrid, but now I'm confused about something:

all the images I find of chytrid victims are of frogs. There's plenty of info on caudates being carriers, but do they get sick? If not, how do any of us really know our critters are chytrid-free?
 

Molch

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ok, to answer my own silly question, I found this:

Chytridiomycosis

which states a few cases of salamanders getting sick in lab experiments but there's not much concrete info from the wild which species and to which extend can become sick (as opposed to being carriers).
 
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It looks to me like most caudate species have a natural immunity to chytrid, but can develop an infection under stressful conditions (in this case, being removed from the wild and placed in captivity).

As for knowing if our captives are carrying chytrid, I've heard there are tests that can be done, but I haven't looked into them. I take great care to insure, that if one of my caudates (or anurans) is carrying chytrid, that there is no cross-contamination between tanks.
 

TikkiDui

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In the UK we have carried out two national chytrid surveys, I dont know if anything like this has been done in the US.
Second National Chytrid Survey - Big Swab 2011 | Projects | ARG UK

It has been found in native newts that have been in contact with invasive species such as american bullfrogs and alpine newts but currently has only been recorded having an effect on natterjack toads. this is not to say it will not effect populations in the future so species need to be tested to monitor the spread of the virus.
 

taherman

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There have been massive declines in some populations of neotropical salamanders in Mexico and Guatemala, and a few species which were extremely abundant in the 1970s are very rare or potentially extinct today.

There are probably a number of reasons why salamander dieoffs are not documented.
1. Salamanders tend to be more cryptic in their behaviors than frogs, and it would be harder for someone to "stumble" on a dieoff of salamanders when it was happening underground or under logs, and there is only a window of a week or so before carcasses are completely decomposed.
2. B.d. likely passed through areas of high salamander density (Appalachia, Mexican/Guatemalan highlands) before the disease was described, and when few people were actively studying these populations. There may have been massive dieoffs, but nobody was looking for them like they have been with frogs now.
3. The remaining salamanders are relatively resistant as you describe, and only exhibit obvious symptoms under stressful situations (i.e. captivity...maybe climatic changes...)

That's what I'd suspect from my experiences.

Tim
 

methodik

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2. B.d. likely passed through areas of high salamander density (Appalachia, Mexican/Guatemalan highlands) before the disease was described, and when few people were actively studying these populations. There may have been massive dieoffs, but nobody was looking for them like they have been with frogs now.

This matches with the foreword to SEMLITSCH Amphibian Conservation, which was written by WAKE. He states (if I remember right) that when he first heard about the fungus (or its results, rather), it was mainly reports on frogs, though little time later he began to recognize the thread, as he was unable to find Plethodontids in Mexico where he knew there were dense populations before.

This reminds me that I still have to read the whole book some time.
 

otolith

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Chytrid has been implicated in the decline of Ambystoma opacum and maculatum in southern Maryland. From what I've heard it sounds like it causes a lot of issues with developing larvae rather than killing breeding adults. Entire vernal pools can become pretty much devoid of frog tadpoles and caudate larvae in a matter of days. I don't know if any of the data is available online but Towson University in MD has been doing studies at numerous vernal pools around the state.
 

peter5930

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well, having some time on my hand today, I've been surfing reading up on chytrid, but now I'm confused about something:

all the images I find of chytrid victims are of frogs. There's plenty of info on caudates being carriers, but do they get sick? If not, how do any of us really know our critters are chytrid-free?

I had my animals tested for chytrid recently by a researcher at the Institute of Zoology in London, and they were all free from it. If you send off some emails and phone around, you might get lucky and find someone in the US who's doing research into chytrid and can test your animals. I worked out a deal where I got my animals tested for free provided I sent any that tested positive to the researcher so that she could try to isolate and culture the strain that they were carrying.

I'm pretty sure I've read about chytrid die-offs in fire salamanders, and I remember something about population density being a factor; some species will tolerate chytrid when the population density is low, but once there are too many animals in the area, the infection gets out of control and the population crashes. I vaguely remember there being a threshold of something like 40 spores/litre of water that the species in question could tolerate (I can't remember what species it was), and that they only died off when the spore count went above that. If that's the case, UV filtration or frequent water changes might prevent an animal that's carrying chytrid from getting sick, which isn't necessarily a good thing, since you'll never know the animal is infected unless it's tested and the infection will be able to spread unnoticed.
 
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