Year of the frog e-petition

We are currently experiencing the greatest extinction event since the death of the dinosaurs 65 million years ago. If you're a UK resident, please consider signing this e-petition to the UK government:

As a result of climate change, and loss of natural habitats, around a third of the World’s species of frogs and other amphibians could be wiped out in the coming years. Hundreds of species are also at risk from an untreatable and unstoppable parasitic fungus which, perhaps exacerbated by global warming, now threatens to kill millions of amphibians around the world. Unless urgent and immediate action is taken now to take priority species into protective captivity, so that they can prosper and breed in safety, these species will face extinction within years. Zoos and aquariums around the world have already joined forces to ensure such schemes take place. The campaign, however, still needs funds and increased public awareness. We are therefore calling upon the Prime Minister to lead the way among Western nations by endorsing and supporting the many and varied conservation programmes currently being carried out by zoos, aquariums in the UK, and by highlighting the campaign among his counterparts internationally.

Call for help: Why do frogs need vitamins?

Shaun asked me: Why do frogs need vitamins - they don't get them in the wild.

Actually, they do - but not out of a bottle. All living organisms need a range of vitamins, although they vary in what they can make and what they must take in through their diet. In the wild, frogs eat a much wider range of food items than the restricted range of insects we give them in captivity, and the wild feeder insects eat a wide range of foods, not just fly-mash, so wild frogs receive quite a lot through their diet.

Animals also need a range of minerals, one of the main ones being calcium (for bones and the nervous system). Insects don't have bones, and compared with vertebrates, they have a reversed calcium:phosphorus ratio, i.e. they contain more phosphorus than calcium, whereas in animals, it's the other way round. Most insects are therefore a poor source of calcium, although soil arthropods such as springtails and woodlice may contain reasonable amounts.

Vitamin D3 is needed to absorb calcium from the diet. In the wild, frogs make vitamin D3 in their skin when 7-dehydrocholesterol reacts with UVB ultraviolet light at wavelengths between 270–300 nm. Frogs kept under UVB illumination in captivity can make their own vitamin D3 - but they also need a wide range of other vitamins and minerals they can't get from a restricted diet, so we supplement their food.

Final point, vitamin D3 oxidizes and is destroyed very rapidly, particularly when damp or in solution. Check the date on your vitamin supplements - I have been supplied out of date vitamins by otherwise reputable suppliers which have had to be replaced. Keep supplements cool, dry and dark, exclude as much air as possible and don't keep them too long - if you don't use them up in 6 months, replace them, even if they are still within date. Once the pack has been opened, the decay begins and the expiry date assumes that they will be kept in a sealed package.

Gosh, I wish I had some good news :-(

Chytridiomycosis survey in wild and captive mexican amphibians. Ecohealth. 2008 5: 18-26
Mexico, a rich country in terms of amphibian diversity, hosts about 375 described species. Population declines have been documented for several species where it is evident that their habitat is being destroyed or modified. However, other species which inhabit pristine areas are declining as well. It has been suggested that the chytrid fungus Batrachochytrium dendrobatidis (B.d.) may be one of the causes of the enigmatic declines in Mexico. We surveyed a total of 45 localities, in 12 states across Mexico, examining a total of 360 specimens representing 14 genera and 30 species. We also examined 91 specimens of Ambystoma mexicanum from a captive population in Mexico City as well as one Pachymedusa dacnicolor obtained in a pet shop. We used a two-tiered technique to detect the pathogen. For wild-caught specimens, we utilized light microscopy to identify presence of B.d. sporangia in amphibian skin. Then, to verify the infection, we used a quantitative real-time PCR assay on collected skin sections which is specific for B.d. For captive animals, we used a nonlethal version of the real-time PCR technique. We found evidence of B.d. infection in 111 animals comprising 14 species in 13 localities. A large percentage (84%) of Ambystoma mexicanum from the colony were infected with B.d. The two most highly infected individuals were the endangered Ambystoma mexicanum, from a captive colony, and Pachymedusa dacnicolor, purchased at a pet shop.



Presence of the chytrid fungus Batrachochytrium dendrobatidis in populations of the critically endangered frog Mannophryne olmonae in Tobago, West Indies. Ecohealth. 2008 5: 34-9
The emerging infectious disease chytridiomycosis is prevalent in Central and South America, and has caused catastrophic declines of amphibian populations in the Neotropics. The responsible organism, Batrachochytrium dendrobatidis, has been recorded on three West Indian islands, but the whole of the Caribbean region is predicted to offer a suitable environment for the disease. Monitoring the spread of chytridiomycosis is thus a priority in this region, which has exceptionally high levels of amphibian endemism. PCR analysis of 124 amphibian skin swabs in Tobago (Republic of Trinidad and Tobago) demonstrated the presence of B. dendrobatidis in three widely separated populations of the frog Mannophryne olmonae, which is listed as Critically Endangered on the basis of recent population declines. Chytridiomycosis is presently endemic in this species, with a prevalence of about 20% and no associated clinical disease. Increased susceptibility to chytridiomycosis from climate change is unlikely in amphibian populations in Tobago, as this island does not have high montane environments, but remains a possibility in the sister island of Trinidad. Preventing the spread of chytridiomycosis within and between these and other Caribbean islands should be a major goal of practical conservation measures for amphibians in the region.

Amphibian Conservation at Marwell Zoo

I recently visited Marwell Zoo to donate some animals to a very exciting conservation project which is starting up there. Marwell Zoological Park is owned and run by Marwell Preservation Trust, a registered charity dedicated to the conservation of wildlife and natural habitats both locally and internationally. Traditionally, the Zoo has concentrated on hoofed animals (they're very proud of their giraffes, and very pretty they are too), but this year, the Zoo has invested very heavily in an amphibian conservation project, Leap 4 Life, part of the Year of the Frog.

The Zoo has just built an extremely impressive amphibian research and breeding facility which has secure biocontainment and where the public will be able to see the work being carried out in the laboratory through large viewing windows. As Marwell points out:

• After thriving for over 360 million years, one third to one half of all amphibian species could disappear in the immediate future.
• For every threatened bird or mammal species, there are 2-3 amphibians nearing extinction.
• Earth is facing the single largest mass extinction since the disappearance of dinosaurs.

Visit: How you can help (lots of fun activities for families and children) or make a donation.

Frogs with Disease-Resistance Genes May Escape Extinction

As frog populations die off around the world, researchers have identified certain genes that can help the amphibians develop resistance to harmful bacteria and disease. The discovery may provide new strategies to protect frog populations in the wild. New work examines how genes encoding the major histocompatibility (MHC) complex affect the ability of frogs to resist infection by a bacterium that is commonly associated with frog population declines. “In the short term, captive management of frogs with complementary disease-resistance genes may offer the best hope for saving species from extinction,” says Bruce Waldman, a biologist at Lincoln University in New Zealand and one of the paper’s authors. “Management practices that maintain or enhance diversity in MHC genes may prove the key to safeguarding frog populations in the wild." "Massive die-offs of frogs may indicate environmental problems that ultimately will affect other species, including humans,” Waldman says. “But, despite the concern, little is known about factors that make individuals susceptible to disease.” Doctoral students Seth Barribeau and Jandouwe Villinger, working with Waldman, exposed African clawed frog tadpoles to several doses of the bacterium Aeromonas hydrophila. They examined the number of tadpoles that survived and measured how fast they grew. Certain genes allowed tadpoles to survive bacterial infection but at a cost, as these tadpoles sometimes grew more slowly. Among siblings, patterns of disease resistance corresponded to tadpoles’ MHC genes rather than other genes that they shared, demonstrating that the MHC genes conferred immunity. Programs currently are underway to rescue frogs from declining wild populations and breed them in captivity to ensure that species are not lost to extinction. This study suggests that selective breeding of individuals with known disease-resistance genes might produce frogs that can survive infection by pathogens, even after the frogs are reintroduced into the wild. The research team studied the African clawed frog because its immune system already had been well characterized, but as most frogs and toads have similar immune systems, they believe that their results will be generally applicable to all threatened and endangered amphibians.

Major Histocompatibility Complex Based Resistance to a Common Bacterial Pathogen of Amphibians. 2008 PLoS ONE 3(7): e2692
Given their well-developed systems of innate and adaptive immunity, global population declines of amphibians are particularly perplexing. To investigate the role of the major histocompatibilty complex (MHC) in conferring pathogen resistance, we challenged Xenopus laevis tadpoles bearing different combinations of four MHC haplotypes (f, g, j, and r) with the bacterial pathogen Aeromonas hydrophila in two experiments. In the first, we exposed ff, fg, gg, gj, and jj tadpoles, obtained from breeding MHC homozygous parents, to one of three doses of A. hydrophila or heat-killed bacteria as a control. In the second, we exposed ff, fg, fr, gg, rg, and rr tadpoles, obtained from breeding MHC heterozygous parents and subsequently genotyped by PCR, to A. hydrophila, heat-killed bacteria or media alone as controls. We thereby determined whether the same patterns of MHC resistance emerged within as among families, independent of non-MHC heritable differences. Tadpoles with r or g MHC haplotypes were more likely to die than were those with f or j haplotypes. Growth rates varied among MHC types, independent of exposure dose. Heterozygous individuals with both susceptible and resistant haplotypes were intermediate to either homozygous genotype in both size and survival. The effect of the MHC on growth and survival was consistent between experiments and across families. MHC alleles differentially confer resistance to, or tolerance of, the bacterial pathogen, which affects tadpoles’ growth and survival.

Dendrobatidae Nederland Magazine