Monday, 26 September 2016

Side effects of itraconazole on post-metamorphic Alytes obstetricans after a cold stress

A small but important study on limitations of the use of itraconazole.

Itraconazole is the most widely used treatment against Batrachochytrium dendrobatidis (Bd), the fungal pathogen causing chytridiomycosis, a proximate cause of amphibian declines. Several side effects of itraconazole treatment, ranging in severity from depigmentation to death have been reported in different amphibian species and life stages, and these side effects were observed at commonly used dosages of itraconazole. However, no studies have investigated side-effects of itraconazole in conjunction with environmental stress. Post-metamorphic midwife toads (Alytes obstetricans) that were treated with itraconazole and subsequently exposed to a cold stress (exposure to 4°C cold water) had higher mortality rates compared to untreated individuals. Moreover, adults of booroolong frogs (Litoria booroolongensis) treated with itraconazole had a higher probability to become infected when subsequently exposed to Bd. Our results suggest that a post-metamorphosis itraconazole treatment of infected midwife toads combined with a subsequent release into the wild may be an ineffective disease mitigation strategy, as the cold stress during hibernation and/or exposure to Bd in the wild may reduce the hibernation emergence rate of treated individuals in this species.

Study accepted in Amphibia Reptilia

The global amphibian trade flows through Europe: the need for enforcing and improving legislation

The global amphibian trade is suspected to have brought several species to the brink of extinction, and has led to the spread of amphibian pathogens. Moreover, international trade is not regulated for *98 % of species. Here we outline patterns and complexity underlying global amphibian trade, highlighting some loopholes that need to be addressed, focusing on the European Union. In spite of being one of the leading amphibian importers, the EU’s current legislation is insufficient to prevent overharvesting of those species in demand or the introduction and/or spread of amphibian pathogens into captive and wild populations. We suggest steps to improve the policy (implementation and enforcement) framework, including (i) an identifier specifically for amphibians in theWorld Customs Organisation’s harmonised system, (ii) Parties to CITES should strive to include more species in the CITES appendices, and (iii) restriction or suspension of trade of threatened species, restricted-range species, and species protected in their country of origin. Commercial trade should not put survival of amphibian species further at risk.

http://link.springer.com/article/10.1007/s10531-016-1193-8?view=classic

Thursday, 11 August 2016

Predicting the future distribution of Bd under climate change

Data from bd-maps.net was used to predict the global future distribution of Bd. The paper was published in PLoS ONE and is freely available. A key model prediction is "a broad expansion of areas environmentally suitable for establishment of Bd on amphibian hosts in the temperate zones of the Northern Hemisphere."



The figure shows the predicted change in the distribution of (figure taken from the paper).

Wednesday, 10 August 2016

Chytrid in crayfish?

A paper published in the journal Aquaculture claims that Bd was detected in farmed crayfish and that Bd causes mortality, pandemics and massive economic losses to aquaculture. The abstract of the paper can be found here. Unfortunately, there are several problems with the study. For example, infections do not look like typical Bd infection. While there are some papers on Bd in crayfish (here), the new paper provides no strong new evidence for Bd in crayfish.



Picture from https://en.wikipedia.org/wiki/Macrobrachium_rosenbergii.

Wednesday, 3 August 2016

Chytrid responsible for one of fastest species declines ever recorded

"Scientists battling to fight a lethal amphibian disease on two islands in Caribbean have witnessed what is believed to be one of the fastest range-wide declines ever recorded for any animal – pushing a critically endangered frog species towards the verge of extinction."

Read more on the website of the Zoological Society of London:
https://www.zsl.org/science/news/chytrid-responsible-for-one-of-fastest-species-declines-ever-recorded

Read the full paper here (open access):
http://www.nature.com/articles/srep30772


Mountain chicken (c) ZSL

Monday, 23 May 2016

(Are there) continental-scale drivers of amphibian decline

A new paper published in Scientific Reports (link) tested whether there are continental-scale drivers of amphibian decline (including Bd habitat suitability). Neither Bd nor other threats were found to be drivers of population decline at the continental level: "Our analysis uses data from across the United States to empirically test the relationship between change in the number of amphibian populations and hypothesized threats. We did not find support for a consistent relationship between rates of amphibian declines and distribution of stressors at the continental level."

An important finding is "that local amphibian populations are being lost from metapopulations at an average rate of 3.79% per year."

Friday, 25 March 2016

Are amphibians evolving tolerance to Bd?

A new paper by Anna Savage and Kelly Zamudio suggests that amphibian populations may be evolving tolerance to Bd. This result is based on the analysis of MHC loci.

The authors write "Our findings indicate that selective pressure for Bd survival drives rapid immunogenetic adaptation in some natural populations, despite differences in environment and demography. Our field-based analysis of immunogenetic variation confirms that natural amphibian populations have the evolutionary potential to adapt to chytridiomycosis."

The paper published in the Proceedings of the Royal Society can be found here:
http://rspb.royalsocietypublishing.org/content/283/1827/20153115