Last year was Year of the Frog (nothing to do with the Chinese calendar, but instead a global effort to raise awareness about the plight of the world's declining amphibian species). I hope that you've not forgotten that the global effort to slow amphibian extinction continues unabated. For various reasons, I haven't blogged about amphibians for a while, so, in an effort to bring balance (something I strive for, yet will always fail to achieve) I feel the need to bring you up to speed. What has happened lately in the world of amphibian conservation? [Pirri harlequin frog shown here: a species that needs saving. Read on].
As you will - I hope - know by now, compelling evidence shows that amphibians worldwide are dying due to infection by the chytrid fungus Batrachochytrium dendrobatidis, known for short as Bd. Many frog populations and species are declining due to Bd infection, and numerous species (more than 120) have not been recorded for the past few decades and appear to have gone extinct as a result of the spread of Bd. You can keep up to date with the amphibian crisis by keeping tabs on Amphibian Ark and Frog Matters and, for more background, please see the links below.
Between February 16th-18th 2009, a team of international experts met at San Diego Zoo for a special meeting on the amphibian crisis. While the global amphibian crisis has become well known, and while zoos and other bodies are becoming increasingly involved in this conservation movement, information on the subject remains widely distributed and 'de-centralised'. One aim of the meeting was to produce the first draft of an all-inclusive manual that addresses amphibian quarantine, facility biosecurity, disease risk assessment, permanent isolation for species destined for reintroduction, and protocols for the testing and treatment of infectious diseases. The manual is due to be completed at the end of this year and you can read more about it here.
As discussed back in December 2007, relatively small sums of money are needed to save individual species. The good news is that this is often possible. In December 2008, captive breeding populations of the Lake Oku clawed frog Xenopus longipes (a recently recognised species that was only named in 1991) were established in both Antwerp and London Zoo. This is great news, meaning that this critically endangered species has been rescued from extinction (for the time being, at least). Endemic to a single volcanic lake in Cameroon, X. longipes is one of 18 species of Xenopus: as is so often the case, most sources only ever mention or discuss one of them (X. laevis, the African clawed frog). Of the 18 species, one was named last year (X. itombwensis Evans et al., 2008 from Democratic Republic of the Congo), and - in addition to X. longipes Loumont & Kobel, 1991 - five others have been named since 1980 (X. amieti Kobel et al., 1980, X. andrei Loumont, 1983, X. boumbaensis Loumont, 1983, X. pygmaeus Loumont, 1986, and X. largeni Tinsley, 1995). As with so many obscure tropical anurans, virtually nothing is known about the biology of X. longipes.
On the subject of recently discovered species, new frogs continue to come in thick and fast. This year has seen the publication of Noble's pygmy frog Noblella pygmaea [shown here], the smallest frog from the Andes (females have an SVL of 12.5 mm) and one of the smallest frogs in the world (Lehr & Catenazzi 2009). Noblella is another member of the recently recognised hyloid clade Strabomantidae, and seems closely related to Holoaden and Euparkerella within the strabomantid sub-family Holoadeninae (Hedges et al. 2009). Of the eight other Noblella species, all but one (Peru Andes frog N. peruviana, named in 1921) have been named since 1976. Other recent additions include three new Peruvian species of the dendrobatid taxon Ameerega (Brown & Twomey 2009) and 12 new Indian rhacophorids (Biju & Bossuyt 2009). Sadly, many of these new species (about 75 new amphibians have been named so far in 2009) seem to be endangered.
In Panama, the El Valle Amphibian Conservation Center (EVACC) saw completion earlier this year and, in April, it opened to the public. This facility is home to hundreds of breeding amphibians and has the world's only captive breeding colonies of the Pirri Range stubfoot toad or Pirri harlequin frog Atelopus glyphus, Cocle mushroom-tongue salamander Bolitoglossa schizodactyla and the Banded horned treefrog Hemiphractus fasciatus. The EVACC serves both as an amphibian 'rescue centre', where Panamanian amphibians are bred, held in quarantine and tested for Bd, and as a visitor education facility. Public education about the amphibian crisis was widely promoted throughout 2008. We need to keep this going, as the problem hasn't gone away!
More bad news
This article from March 2009 explained how the Dominican white-lipped frog Leptodactylus fallax - the so-called 'Mountain chicken' - has gone into rapid, catastrophic decline on Montserrat in the Caribbean. It's suspected that the Bd that is killing the frog was introduced by other frog species that travelled to the island in banana shipments. The same thing happened on Dominica in 1992, with about 80% of all white-lipped frogs dying within 15 months of the chytrid's arrival.
Indeed the spread of Bd is surprisingly rapid. Studies in Panama have shown that it is moving south by about 20 km (13 miles) a year, and by the time it's noticed, it's a matter of a few months before hundreds and even thousands of dead and dying frogs are present in the area.
And Bd continues to be discovered in new areas. In late May 2009 it was reported from the Philippines (the third Asian country where Bd infections have been recognised): of the country's more than 100 species, Bd has so far been reported in the Luzon striped frog or Laguna del Bay frog Hylarana similis, Luzon stream frog H. luzonensis, Woodworth's wart frog Limnonectes woodworthi, the Big-headed wart frog or Luzon fang frog L. macrocephalus, and the Common puddle frog Occidozyga laevis. The two Hylarana species are ranids, while Limnodectes and Occidozyga are dicroglossids. The Luzon striped frog has been particularly badly affected and has gone into chronic decline in at least part of its range.
Needless to say, there is still lots of work to do. You can play your part by donating: donations can be made to the EVACC here, to Amphibian Ark here (you can, literally, save a species), and a special effort to save the Pirri harlequin frog Atelopus glyphus [shown at the very top] is underway here. And, if you haven't already done so, please sign Amphibian Ark's online petition (it takes less than one minute, if that). Or, if you just want to stay informed, do check out Amphibian Ark and Frog Matters.
For previous articles on amphibian conservation see...
- Get ready for 2008: Year Of The Frog
- The EDGE amphibian project launches today
- California's declining frogs
- It is still Year of the Frog
- A world without Baw Baw frogs?
And for a (near-complete, but not complete) review of anuran diversity see...
- Frogs and toads: sheer, untold awesomeness
- Oh, to be a so-called 'transitional anuran'
- Ghost frogs, hyloids, arcifery.. what more could you want?
- Green-boned glass frogs, monkey frogs, toothless toads
- Of short-heads, shovel-snouters and squeakers: an afrobatrachian's tale (part I)
- Polymorphism, squeakers, the hairy frog: an afrobatrachian's tale (part II)
- Flying frogs, goliath frogs, and the one who can eat 16-and-a-half baby cobras
Refs - -
Biju, S. D. & Bossuyt, F. 2009. Systematics and phylogeny of Philautus Gistel, 1848 (Anura, Rhacophoridae) in the Western Ghats of India, with descriptions of 12 new species. Zoological Journal of the Linnean Society 155, 374-444.
Brown, J. L. & Twomey, E. 2009. Complicated histories: three new species of poison frogs of the genus Ameerega (Anura: Dendrobatidae) from north-central Peru. Zootaxa 2049, 1-38.
Hedges, S. B., Duellman, W. E. & Heinicke, M. P. 2008. New World direct-developing frogs (Anura: Terranura): molecular phylogeny, classification, biogeography, and conservation. Zootaxa 1737, 1-182.
Lehr, E. & Catenazzi, A. 2009. A new species of minute Noblella (Anura: Strabomantidae) from southern Peru: the smallest frog of the Andes. Copeia 2009, 148-156.
It should be mentioned that the spread of Bd uphill, into tropical mountains, appears to have been made possible by global warming.
Yes, for more on that see...
Pounds, J. A., Bustamante, M. R., Coloma, L. A., Consuegra, J. A., Fogden, M. P. L., Foster, P. N., La Marca, E., Masters, K. L., Merino-Viteri, A., Puschendorf, R., Ron, S. R., SÃ¡nchez-Azofeifa, G. A., Still, C. J. & Young, B. E. 2006. Widespread amphibian extinctions from epidemic disease driven by global warming. Nature 439, 161-167.
One question I have never seen addressed in the 'general' press: Once the chytrid fungus establishes itself, how is the environment ever restored or remediated to enable frogs to be reintroduced to their previous range? Or are these 'saved' species doomed to be zoo specimens only from now on? (Sorry if I've missed a major post on this very subject)
Wasn't there a species of frog that managed to develop some resistance to the fungus? Since it is supposedly of african origin said amphibian must be african as well
It's a little unsettling to read about Bd in the Philippines; for some reason, there doesn't seem to be much emphasis on amphibian declines here in Southeast Asia. Habitat loss appears to be the primary threat. However, if Bd has the potential to be just as devastating to frogs in the region, then I am a little worried. Hylarana, Limnonectes and Occidozyga are relatively widespread, and species belonging to these 3 genera occur in Singapore. If they are just as susceptible to Bd as their relatives in the Philippines, then we might be in some serious trouble.
Thanks for comments (though it's a shame that amphibian conservation stirs up less apparent interest than much of the other stuff I write about)...
Resistance to Bd (comment 4): there has been some speculation that populations of some species (like the Mountain yellow-legged frog Rana muscosa in California, and Columbia spotted frog R. luteiventris in Wyoming) have developed or exhibit resistance, but this is mostly speculative and for a discussion go here. The Boreal toad Anaxyrus boreas seems to be quite resistant. I have been very surprised to learn that the European common brown frog R. temporaria is (apparently) resistant to Bd: surprised because there have been numerous local die-offs here in Southampton, and I assumed that these were because of Bd infection. Xenopus laevis (African clawed frog), Lithobates catesbeiana (American bullfrog) and Rhinella marina (Cane toad) all exhibit high resistance, which is part of the problem given that these are widespread invasive species.
One idea is that the bacteria that occur naturally on the skin of these species (or on some populations of these species, at least) might inhibit or slow infection by Bd.
Oh yeah: WRT to my comment 'amphibian conservation stirs up less apparent interest than much of the other stuff I write about', I know that this is not really fair - look at the spike on the Bravenet counter at bottom left.
L. catesbeianus. Lithobates is a he.
Oh yeah, thanks. One day I'll remember this sort of stuff. You look at names and comprehend their linguistic context. I look at them and just see labels: I honestly do not find myself thinking about genders and whatnot. Of course, maybe I create problems for myself by using new taxonomic names (though, I do that because it's right to do so).
Hey - what was the deal with the bacon at that Serbian wedding?
You look at names and comprehend their linguistic context.
Not always. For example, I don't actually know Greek. :-)
Hey - what was the deal with the bacon at that Serbian wedding?
It was part of the meal, and that's relevant to open threads ever since this thread. (Don't read just the first comment.)
Its overall wonderful that so small creatures receive so much interest.
I however, cannot help but ask: was any research on curing this fungus? I heard that simple wiping a frog with common medicine worked. Or, better, some vaccine which can be spread in wild populations? Do we have emergence of resistant frog populations and loss of virulence of the fungus, towards ecological equilibrium, like one would expect from parasite ecology? For how many frog species we can really be sure they died off - they are mostly very underresearched?
Resistance could be population-based, rather than species. Resistance in individuals is probably the only hope for many exposed populations' futures.
I was a bit surprised to hear a parasite blamed, but this particular fungus can get away with quickly killing the hosts, since the spores remain viable for a good long time in the environment (possibly long enough to use reproductive behaviors for exposure).
I realized after posting that if the fungus uses primarily reproductive behaviors, that might explain its virulence: it would have a fairly narrow time window to infect, reproduce, and get spores released for more current hosts (better) and the next wave of reproducers (adequate). It not only can afford to kill hosts, but to generate sufficient offspring numbers, it may be advantageous to kill them. Makes sense - that's almost always the underlying selection for continued nastiness in a disease organism.
I found this very interesting PDF (linked from my name, below), noting(*):
Reasons why Bd would be ineffective as a
tool to eradicate coqui from Hawaii1. Relative to other amphibians, coqui are not very susceptible to Bd2. Bd is already present in the Hawaiian Islands and does not seem to be causing mass mortalities3. Summer temperatures may be too high for Bd to be effective4. Other potential hosts of Bd are not known
So, not only do coqui frogs keep us awake, refuse to eat mosquitoes, eat what does eat mosquitoes, they are resistant to Bd. Who was it said "intelligent design" implies "malicious design"?
(*) Hawaii has no native amphibians, and agricultural exports are carefully controlled, so it was not actually insane to consider the question.
3. Summer temperatures may be too high for Bd to be effective
Now it gets interesting.
I heard there actually is a way to control the fungus (but I use that term lightly) by treating the amphibians as juveniles (read it in National Geographic, so I don't know how accurate that statement is). But it essentially involved cleaning the amphibians of the fungus for several generations and allowing the frogs and salamanders to build an immunity.
Well, there is at least some good news about amphibians. I read about a study in Reptiles magazine recently that found tree frog tadpoles (specifically, gray tree frog tadpoles) to be somewhat resistant to many pesticides which kill other amphibians. Of course this helps squat with chytrid fungus. Maybe we will see a second big radiation of amphibians out of tree frogs if this chytrid fungus/amphibian extinction thing gets really bad.
Metalraptor: ... for some definition of "we".
Completely hijacking the thread, but since this is where all the tetrapod people hang out ...
Does anyone know of a comprehensive published osteology of any varanid lizard? I am in the process of taking one apart, and I'm worried about getting all the bits back together properly once I have it cleaned down to bones. References appreciated; PDFs even better! Thanks in advance.
Comment 16: Maybe we will see a second big radiation of amphibians out of tree frogs if this chytrid fungus/amphibian extinction thing gets really bad.
The bad news would be a new radiation of amphibians could take centuries do spread, and meanwhile?
Batrachochytrium dendrobatidis: I'm not familiar with it, random questions: Does it affect the lungs? Is the African clawed frog immune because it is aquatic and primarily breathes through the skin and lacks a throat sac as spore depot? Is it related to the bat white nose syndrome, which has a unique respiratory situation of cold humid cave social groups?