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News Article | April 19, 2017
Site: phys.org

The situation is alarming: The invasive Asian fungus has recently led to mass mortality of fire salamanders in the Netherlands, Belgium and Germany. Only small numbers of the black-yellow amphibian have survived the invasion of Batrachochytrium salamandrivorans - the "devourer of salamanders." The aggressive fungus, which presumably came to Europe through the amphibian trade, affects the skin of the animals, leading to the formation of skin necrosis and ultimately death. The death rate is extremely high, as a study by researchers in the team of Benedikt Schmidt has proven. Schmidt, research group leader at the Department of Evolutionary Biology and Environmental Sciences at the University of Zurich and academic associate for the Swiss Amphibian and Reptile Conservation Programme, says, "Our mark-and-recapture data shows that only 13 percent of the infected salamanders survive over a 10-day period." And, if that were not enough: "The numbers also show that a third of the healthy salamanders became infected with the fungal disease in the same time period." According to An Martel, head of the study and professor at the University of Ghent in Belgium, it is therefore not surprising that an afflicted population shrinks by more than 90 percent within just a few weeks and then disappears. This fungus is the "perfect" enemy The aggressive fungus from Asia has not yet been found in Switzerland. "We must do everything to make sure it stays that way and the disease does not continue to spread," biologist Schmidt warns. Once the "devourer of salamanders" arrives, its epidemiological properties as a "perfect" pathogen make it a deadly enemy: Infection experiments demonstrate that salamanders are not able to build up a resistance to the pathogen. In addition, mere contact with a just a few fungus spores suffice for an infection that ends in death. The fungus also has resistant spores that are not strongly affected by weather conditions and are able to survive for a long time in the environment. Other amphibian species such as the alpine newt react less sensitively to Batrachochytrium salamandrivorans; what is lucky for the alpine newt, however, involves an additional risk: "More robust species may act as a reservoir," Benedikt Schmidt explains. The fungus therefore lives on, even after more sensitive animals like the fire salamander have already long died. According to Schmidt, all these factors make it almost impossible to save a salamander population in its natural environment once infected. "Reintroduction would also have few prospects for success as the spores are able to survive in nature for a long time." If the fungus continues to propagate in Europe, it will pose a great danger to the diversity of European salamanders, many of which are already endangered and on the red list in many countries. Since the fungal disease has initially been limited to a small area, an attempt is being made to prevent it from spreading further: The European Union has launched a research project to create the scientific basis for the control of the "devourer of salamanders" as quickly as possible. Exotic salamanders and newts are often kept as pets and imported in large numbers: Between 2001 and 2009, for example, more than two million fire belly newts, the carriers of the fungal disease, were shipped to the United States. For this reason, both Switzerland and the United States preventively prohibited the import of salamanders and newts. "In case of invasive diseases, this is an unavoidable measure," Schmidt says in support of the measure, "even if trade restrictions are unpopular." More information: Gwij Stegen et al. Drivers of salamander extirpation mediated by Batrachochytrium salamandrivorans, Nature (2017). DOI: 10.1038/nature22059


News Article | April 19, 2017
Site: www.eurekalert.org

The situation is alarming: The invasive Asian fungus has recently led to mass mortality of fire salamanders in the Netherlands, Belgium and Germany. Only small numbers of the black-yellow amphibian have survived the invasion of Batrachochytrium salamandrivorans - the "devourer of salamanders." The aggressive fungus, which presumably came to Europe through the amphibian trade, affects the skin of the animals, leading to the formation of skin necrosis and ultimately death. The death rate is extremely high, as a study by researchers in the team of Benedikt Schmidt has proven. Schmidt, research group leader at the Department of Evolutionary Biology and Environmental Sciences at the University of Zurich and academic associate for the Swiss Amphibian and Reptile Conservation Programme, says, "Our mark-and-recapture data shows that only 13 percent of the infected salamanders survive over a 10-day period." And, if that were not enough: "The numbers also show that a third of the healthy salamanders became infected with the fungal disease in the same time period." According to An Martel, head of the study and professor at the University of Ghent in Belgium, it is therefore not surprising that an afflicted population shrinks by more than 90 percent within just a few weeks and then disappears. The aggressive fungus from Asia has not yet been found in Switzerland. "We must do everything to make sure it stays that way and the disease does not continue to spread," biologist Schmidt warns. Once the "devourer of salamanders" arrives, its epidemiological properties as a "perfect" pathogen make it a deadly enemy: Infection experiments demonstrate that salamanders are not able to build up a resistance to the pathogen. In addition, mere contact with a just a few fungus spores suffice for an infection that ends in death. The fungus also has resistant spores that are not strongly affected by weather conditions and are able to survive for a long time in the environment. Other amphibian species such as the alpine newt react less sensitively to Batrachochytrium salamandrivorans; what is lucky for the alpine newt, however, involves an additional risk: "More robust species may act as a reservoir," Benedikt Schmidt explains. The fungus therefore lives on, even after more sensitive animals like the fire salamander have already long died. According to Schmidt, all these factors make it almost impossible to save a salamander population in its natural environment once infected. "Reintroduction would also have few prospects for success as the spores are able to survive in nature for a long time." If the fungus continues to propagate in Europe, it will pose a great danger to the diversity of European salamanders, many of which are already endangered and on the red list in many countries. Since the fungal disease has initially been limited to a small area, an attempt is being made to prevent it from spreading further: The European Union has launched a research project to create the scientific basis for the control of the "devourer of salamanders" as quickly as possible. Exotic salamanders and newts are often kept as pets and imported in large numbers: Between 2001 and 2009, for example, more than two million fire belly newts, the carriers of the fungal disease, were shipped to the United States. For this reason, both Switzerland and the United States preventively prohibited the import of salamanders and newts. "In case of invasive diseases, this is an unavoidable measure," Schmidt says in support of the measure, "even if trade restrictions are unpopular."


Beebee T.,Amphibian and Reptile Conservation | Beebee T.,University of Sussex
Herpetological Bulletin | Year: 2012

Common toads Bufo bufo have declined over much of southern and eastern England in recent decades where other widespread amphibian species have remained relatively stable. One such toad decline, at Offham marshes in Sussex, was investigated over the fifteen year period 1998-2012 immediately subsequent to a tenfold decrease in population size between 1989 and 1997. Syntopic amphibians (Rana temporaria, Lissotriton vulgaris and L. helveticus) probably also declined at this site. The surviving toad population continued to recruit new cohorts and had an apparently healthy age structure. Habitat quality (aquatic and terrestrial) remained good and there was no evidence of disease. An invasive species (Pelophylax ridibundus) was excluded as a likely cause of toad decline. However, traffic on a neighbouring road rendered more than half the previously available terrestrial habitat for toads essentially unreachable. Furthermore, reduced management of vegetation in ditches where the toads breed apparently increased mortality of developing tadpoles. Future prospects for conserving and increasing the toad population are discussed.


Buckley J.,Amphibian and Reptile Conservation | Beebee T.J.C.,Amphibian and Reptile Conservation | Schmidt B.R.,University of Zürich
Animal Conservation | Year: 2014

Amphibian declines around the world are a major conservation concern. Monitoring trends in abundance is therefore important. Exemplar models are required, with robust, easily assessed indicators of population size that have high and consistent detection probability and which can be quantified over large geographical scales. Natterjack toads Bufo calamita potentially fulfil these criteria. This amphibian is rare and increasingly endangered in the north European part of its range, including Britain. In this paper, we analyse data on population size (based on spawn string counts) and breeding success (toadlet production) collected over 20 years from all remaining natterjack sites in the UK, permitting for the first time an assessment of population trends of an endangered amphibian at the national scale. State-space models, which account for observation error, were developed to estimate population trends and to assesss the effects of conservation management. Between 1990 and 2009, the British population of B.calamita was approximately stable as judged by spawn string counts and broadly confirmed by state-space modelling, although this indicated that continuing small decline was more probable than stability. Empirical and model analyses also demonstrated that population growth rate was influenced positively by frequency of breeding success (toadlet production) and by grazing of the terrestrial habitat by domestic livestock. The implications of these findings for future conservation management of B.calamita are discussed. © 2013 The Zoological Society of London.


Beebee T.J.C.,Amphibian and Reptile Conservation
Journal of Herpetology | Year: 2014

Agricultural intensification, starting during the Second World War, precipitated declines in all seven native species of amphibians in Britain. Problems in the United Kingdom (U.K.) therefore predated recognition of global amphibian declines and were due to relatively simple causes, notably habitat modification and destruction. Pesticides, acid rain, ultraviolet radiation, climate change, and disease have thus far proved relatively minor issues. Amphibian conservation started in the 1970s, initially with status surveys, but by the 1980s research into habitat requirements and proactive management was underway, particularly for the rare Bufo calamita (Natterjack Toad). The relatively widespread Triturus cristatus (Great Crested Newt) was given the same legal protection as B. calamita in 1981 due largely to declines elsewhere in Europe. This protection has become problematic for conservationists on account of the many sites with this newt that regularly come under threat from development. Additional difficulties identified in the 1990s included serious impacts of road mortality on Bufo bufo (Common Toad) and inbreeding in urban populations of this species and of Rana temporaria (Common Frog). A previously unrecognized rare native, the "northern clade" of Pelophylax (formerly Rana) lessonae (Northern Pool Frog) became extinct in the early 1990s but was reintroduced in the 2000s. In the past 4 decades conservation efforts have stabilized, although not increased, the U.K B. calamita population, but some of the widespread species are still declining, albeit at a slower rate than in the postwar period. Effective methods for amphibian conservation are now available and the outstanding question is whether there will be sufficient funding to make greater gains in future. Copyright 2014 Society for the Study of Amphibians and Reptiles.


Beebee T.J.C.,Amphibian and Reptile Conservation
Journal of Zoology | Year: 2011

Severe recent declines of amphibians around the world have highlighted the need to identify factors that affect their population dynamics and viability. This study used a long-term (>30years) dataset collected for a British population of natterjack toads Bufo calamita, a rare and endangered species in much of northern Europe. Modelling was employed to test a series of hypotheses concerning the effects of anthropogenic (conservation management) and climatic factors on toad demographics. The best models accounted for >72% of the variance in population size, as judged by spawn string counts, between 1975 and 2007. Conservation management (pond creation) was important, as were spring and summer climate variables relating to larval survival, and winter conditions associated with hibernation mortality. The implications of trends associated with future climate change are also considered. © 2011 The Authors. Journal of Zoology © 2011 The Zoological Society of London.


Beebee T.,Amphibian and Reptile Conservation
Herpetological Bulletin | Year: 2012

Many species of amphibians have bred in a Woodingdean garden pond for more than 30 years. In summer 2007 an outbreak of Ranavirus occurred and this paper describes its impact on three species of anurans living wild in the garden and two species kept in an outdoor vivarium. Common frog Rana temporaria numbers were reduced by >80%. Common toads Bufo bufo decreased by perhaps 20% whereas pool frogs Pelophylax lessonae were scarcely affected. A single natterjack B. calamita died in the vivarium where at least five survived, but all midwife toads Alytes obstetricans (adults and larvae) in the same enclosure perished. There was no sign of recovery of the common frog population over the ensuing five years.


Smith R.K.,University of Cambridge | Dicks L.V.,University of Cambridge | Mitchell R.,Amphibian and Reptile Conservation | Sutherland W.J.,University of Cambridge
Conservation Evidence | Year: 2014

This editorial highlights the deficit of studies that directly compare different conservation interventions for the same threat. Most studies test a single intervention (86% in Conservation Evidence), comparing it against a control that lacks the intervention. Such studies can provide evidence that a particular intervention is effective, but do not inform a practitioner whether that intervention is the best option relative to others. Comparing results from different studies is difficult, as outcomes depend on factors such as the site, species and method of measurement. We suggest that a key step to understanding the effectiveness of conservation interventions is to compare different interventions in the same context within studies. If widely adopted this could transform global conservation practice. We provide some guidance on how to design and conduct comparative studies.


Beebee T.J.C.,Amphibian and Reptile Conservation | Buckley J.,Amphibian and Reptile Conservation
Herpetological Journal | Year: 2014

Counting cumulative numbers of spawn strings deposited by female natterjack toads Bufo calamita is widely used in Britain as a surrogate estimator of trends in population size. We analysed long-term data from 20 of the best recorded British natterjack populations to assess the relationship between spawn count and population dynamics. Spawn count, toadlet production and numbers of ponds producing toadlets were all correlated. However, high spawn deposition was more likely the cause of high toadlet production than a converse mechanism in which high toadlet production might subsequently increase adult population size. Good toadlet years did not generally correlate with spawn deposition three years later, the expected delay for cohort maturation. Conversely, new ponds could trigger large increases in spawn deposition within a year of their construction. This situation presumably arose because only a fraction of the available adult females usually breed in any one year. We conclude that although spawn string counts and actual female population size were not demonstrably synonymous, spawn counts probably do reflect relative sizes between populations and temporal trends within them except when numbers of productive ponds also change significantly over short timescales. Individual ponds can remain productive of toadlets for at least 25 years provided the habitat is managed appropriately.


Beebee T.J.C.,Amphibian and Reptile Conservation
Conservation Biology | Year: 2013

Road mortality is a widely recognized but rarely quantified threat to the viability of amphibian populations. The global extent of the problem is substantial and factors affecting the number of animals killed on highways include life-history traits and landscape features. Secondary effects include genetic isolation due to roads acting as barriers to migration. Long-term effects of roads on population dynamics are often severe and mitigation methods include volunteer rescues and under-road tunnels. Despite the development of methods that reduce road kill in specific locations, especially under-road tunnels and culverts, there is scant evidence that such measures will protect populations over the long term. There also seems little likelihood that funding will be forthcoming to ameliorate the problem at the scale necessary to prevent further population declines. © 2013 Society for Conservation Biology.

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