The importance of biosecurity in amphibian conservation
As many of you may be aware amphibians are the most threatened group of vertebrates with 41% of all species currently facing extinction. One of the main driving forces of amphibians over the past 100 years has been a loss of habitat due to an ever expanding human population. Another issue which the average person often overlooks is disease. The amphibian chytrid fungus (Batrachochytrium dendrobatidis, also known as Bd) was discovered in 1998 and has since been implicated in the extinction of 200 species and extirpation of countless others across the globe. The disease has likely been spread through the pet trade, through the farming of bullfrogs (Lithobates catesbeianus) and through the use of African clawed frogs (Xenopus laevis) as a pregnancy test. This last statement may sound bonkers but please do go and research it in your own time, you’re sure to be amazed.
In 2013 a novel chytrid fungus was discovered in the Netherlands after fire salamanders in the country declined by 96% over the course of 3 years. The disease has since been found in Germany and Belgium in the wild. Worryingly the disease has been found in captive collections across Europe including the UK. This new chytrid fungus was given the scientific name Batrachochytrium salamandrivorans which means ‘the devourer of salamanders’, it’s called Bsal for short. We still know very little about Bsal in terms of it’s ecology although some recent and upcoming research aims to shed light on the matter. As we have a model in the case of Bd on how a pathogen can spread and how deadly it can be to some species, with such a virulent fungus as Bsal perhaps we should be more vigilant.
The great crested newt (Triturus cristatus)
As Bsal is already present in the UK, more needs to be done to ensure that it doesn’t spillover into the wild. Water that is potentially contaminated should be sterilised thoroughly by hobbyists before being poured down drowns or being released into the environment. The same has to be done with any substrate used to give captive salamanders a more naturalistic home. Sick salamanders should not be released into the wild but instead should be screened for the presence of disease. The blame can’t wholly be put on hobbyists, researchers and anyone else who used the environment for recreational purposes must also be careful. When moving between sites they must have a strict biosecurity protocol including the use of Virkon to ensure that all of the fungal spores have been killed. This step not only helps protect against spreading Bsal but also against other amphibian pathogens such as Ranavirus and amphibiocystidium etc. Steps like this must also be taken to ensure that non-native species, such as Crassula helmsii, do not invade freshwater habitats that are inhabited by our more delicate amphibian species.
If Bsal were to be found in the UK in the wild, it could spell the end of our beloved great crested newt (Triturus cristatus) as they are our only native species that is particularly susceptible to the fungus. As someone that works with them on a frequent basis I too have had to up my biosecurity protocol due to the paranoia of accidentally spreading Bsal between my survey sites. If you’re worried and want to know more, don’t worry there is plenty of information available on the web.
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Steve Allain
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