Batrachochytrium salamandrivorans in Germany

The European fire salamander (Salamandra salamandra) is a widespread species that occurs in a variety of habitats throughout its range. We studied if different environmental parameters influence presence as well as abundance of lar-vae within different local landscape units across a more than 5,000 km² large Central European study area. This knowledge is crucial to differentiate between habitat specific absence/low abundance and externally triggered extinctions or population declines, e.g. through newly emerging infectious diseases. Within our study area, the salamander plague, caused by the invasive fungus Batrachochytrium salamandrivorans, has recently been invoked as major factor for population declines in S. salamandra. We estimated larval habitat preferences of 135 European fire salamander populations (presence-absence only), and estimated larval abundances in 85 out of them. In the entire study area, regardless of landscape units, presence of European fire salamander larvae was positively affected by low elevation, a high number of pools (preferred larval micro-habitats) and a high amount of consumable macrozoobenthos in the reproduction creeks as well as a high proportion of forest cover in the surrounding terrestrial habitats. Apart from some minor differences among landscape units when they were analysed separately, we observed in many cases a positive effect of a high number of pools (11 out of 56 overall models = 20%) and, furthermore, a negative effect of a late mapping date (mainly due to larval drift caused by heavy rainfalls in early summer and metamorphosis) on larval abundances (12 out of 56 overall models = 21%). Consequently, at least in this Central European study area, which includes mountainous regions up to 700 m a.s.l. ('West-and Osteifel' , 'Hunsrück'), a mainly agriculturally used lime soil plateau ('Gutland') and a river valley ('Moseltal'), these habitat preferences can be used to differentiate between habitat-caused and disease-caused absence of European fire salamanders and also population declines using the larval population.

The European urodelan diversity is threatened by the recent range expansion of the chytrid fungus Batracho chytrium salamandrivorans. The fire salamander can be classified as especially sensitive as infection of individuals with this parasitic fungus usually leads to chytridiomycosis and rapid mortality. Hence, to observe effects at the population level, it is crucial to monitor population sizes and trends. The abundance of adult fire salamanders is far more difficult to estimate compared to larval stages. Therefore, population monitoring of fire salamanders focusses on the aquatic larvae. We examined abundances of larval fire salamanders in two different first-order creeks. Four different methods were compared: two simple count methods, and two abundance estimates using removal sampling and capture-mark-recapture (CMR), respectively. The results of the count methods strongly correlated with the abundance estimates. Furthermore, the results of the removal sampling correlated with the estimates using CMR data. The estimates of the CMR study should get closer to real larval abundances in the creeks compared to the estimates of the removal sampling approach. Count methods but also removal sampling analysis underestimate real larval abundances. Due to (i) the strong correlations of the results, (ii) less time and cost effort of removal sampling compared to CMR, we suggest the removal sampling method, keeping in mind that real larval population is larger.

Emerging infectious diseases are one of the main suggested reasons for global amphibian decline. Fungal agents play a key role. Since its introduction, the Asian pathogen Batrachochytrium salamandrivorans has driven the Europe-an fire salamander, Salamandra salamandra, to the edge of extinction in the Netherlands and caused severe population declines in Belgium and Germany. We screened 1,526 amphibians (1,431 urodelans and 95 anurans) from 50 sites in a 1,500 km² large area in Germany, south of the next known infected populations. Furthermore, we conducted a presence-absence mapping of larval salamanders in 88 randomly selected creeks and creeks where salamanders had been reported in the past using a standardized removal sampling approach. Our results revealed an expanded distribution of the pathogen in Western Germany and we could detect seven infected urodelan populations including the southernmost locality of the fungus in its exotic range. Larval salamanders were found in 54 out of 63 creeks south, but only in seven out of 25 creeks north of a highway that divides the study area. Bsal infection could mainly be detected in newts (Ichthyosaura alpestris and Lissotriton helveticus) because many previously known European fire salamander populations most likely disappeared in the affected forest regions, however, silently and without observed mass mortalities. The only detectable salamander population north of the highway was found to be Bsal-infected at high prevalence in 2019, but not from 2016 to 2018, suggesting a recent infection event. Overall, prevalence at the individual (2.6%) and population level (14%) was very low. Moreover, modelling habitat suitability in seemingly unaffected areas suggests that most reproduction creeks and surrounding land habitats in the seemingly affected area are still suitable for S. salamandra, supporting our suspicion that the absence of the species is disease-related rather than habitat related.

The salamander plague, caused by the amphibian chytrid fungus Batrachochytrium salamandrivorans (Bsal), is one of the most devastating amphibian diseases, currently threatening the entire Western Palearctic caudate diversity with extinction. Apparently of Asian origin and recently introduced into Europe, Bsal is known from currently ca. 80 sites in the wild in four European countries. Germany is the Bsal 'hotspot' , with more than half (N = 50) of all known European records to date. We here present data based on > 8,500 caudate specimens sampled for Bsal mainly via skin swabbing and quantitative real time PCR (> 3,300 since 2019). Within regions of Bsal occurrence ~ 6-7% of the studied caudates were Bsal-positive. The oldest known European record of the pathogen is from this country (2004), but a massive Bsal dispersal has only been recognized within the last five years with 17 new Bsal sites since 2019 alone. Currently, Bsal is spreading within the northern and the southern Eifel and-since 2017-the Ruhr District. Most recently, the pathogen was for the first time detected in southern Germany (Bavaria) and a further range expansion is expected. A new species distribution model (SDM) of Bsal based on > 100 native and invasive records predicts suitable areas in most parts of Germany. Bsal affects all five caudate species known from these regions and has catastrophic effects on the European fire salamander (Salamandra salamandra). All affected populations in Germany (as well as Belgium and The Netherlands) have dramatically declined. While some may have become extinct due to the salamander plague, in most Bsal-positive sites European fire salamanders can still be recorded at low numbers (at least via systematic larval surveys), and at least one population seems to have recovered as currently Bsal detection remains negative. Little is known about the effect of Bsal on newts, and both prevalence and individual infection load can vary greatly over time, even within one population. However, the situation of the northern crested newt (Triturus cristatus) is alarming, as this species also undergoes declines due to Bsal invasions at some sites. Although some anurans are suggested as potential Bsal reservoirs and transmitters, we detected Bsal in only one individual of the common frog (Rana temporaria) out of 365 anurans of various species tested. Co-infection of Bsal with the related chytrid taxon Batrachochytrium dendrobatidis is known from three taxa (S. salamandra, T. cristatus, Ichthyosaura alpestris) and at four sites. The alarming data from Bsal in Germany call for immediate conservation action at all levels, including ex situ conservation. We therefore strongly support the establishment and implementation of a national Bsal Action Plan.

The invasive chytrid fungus Batrachochytrium salamandrivorans (Bsal) is one of the most devastating amphibian pathogens that was introduced to Europe, where it is threatening the entire Western Palearctic urodelean diversity, especially the European fire salamander Salamandra salamandra. So far, Germany represents the most affected country with almost 50 Bsal-positive sites, mainly concentrated to two regions, Eifel Mountains (Northrhine-Westfalia and Rhineland-Palatine) and Ruhr District (Northrhine-Westfalia). Here we provide the first evidence for the occurrence of Bsal in southern Germany. The pathogen was detected in the nature park Steigerwald, located in the north of the state Bavaria constituting the first record of the pathogen within this state, at a distance of more than 250 km distance from other previously known records.

The chytrid fungus Batrachochytrium salamandrivorans (Bsal), recently introduced from Asia to Europe, causes mortality in numerous species of salamanders and newts and has led to catastrophic declines and local extinctions of the European fire salamander (Salamandra salamandra) in the Netherlands, Belgium, and Germany. Due to the continuous spread of the pathogen, Germany can be considered as the current 'hotspot' of Bsal-driven salamander declines. The pathogen was detected in 2015 in the Eifel Mountains where it probably has been present at least since 2004. Moreover, Bsal was found in 2017 in the Ruhr District where it also might occur since 2004. The Ruhr District is a heavily urbanized and industrialized region in western Germany, which offers an unprecedented opportunity to monitor range expansion and infection dynamics of Bsal in an area affected by intense human activities. We here review the current knowledge on Bsal in the Ruhr District where the pathogen by now has been recorded based on qPCR data from 18 sites distributed over eight cities. Transect counts (adult salamanders) and larval removal-sampling at two sites where Bsal was recorded in 2017 and 2018, confirm that fire salamander populations at the affected sites have declined dramatically. However, single negative-tested individuals were still observed and reproduction could be ascertained. Moreover, we successfully detected Bsal by analysing environmental DNA (eDNA) from samples obtained from a standing water body as well as a stream. Detailed monitoring of a site in Essen (Kruppwald) from January to May 2019 provided data on infection and disease dynamics during an acute Bsal-outbreak in a population of European fire salamanders. After initial observation of single dead infected salamanders in January and February 2019, the maximum Bsal loads in the population ranged from 7.90E+03 ITS copies in early March to 2.29E+09 ITS copies at the end of March. Prevalence of infection ranged from 4% to 50% and significantly increased over time; prevalence of externally visible disease symptoms peaked on May 2 and May 8. Single dead salamanders were encountered throughout the monitoring period. Recaptures of two infected salamanders indicated an increase of Bsal load by about one order of magnitude within one week. Infected salamanders showed small-sized regular round ulcerations usually of 0.25-1 mm but sometimes up to 2.5 mm in diameter, which gave the impression of outward growth from the centre of each ulceration. Among salamander individuals monitored in the Kruppwald, such ulcerations were only found in infected salamanders, but we found no significant correlation between the intensity of the ulcerations and Bsal load. Heat treatment proved effective to cure even deep ulcerations when sala-manders were kept for 10 days at 25-27°C or 14 days at 25°C, but infection persisted and ulcerations reappeared six weeks after the end of the treatment; only heat treatment at 25°C for 21 days proved effective to reliably clear the infection in three tested salamanders.

Der Erreger der als Salamanderpest bezeichneten Amphibienhauterkrankung - der Chytridpilz Batrachochytrium salamandrivorans - ist inzwischen an mehreren Standorten in Mitteleuropa (in den Niederlanden, Belgien und Deutschland) nachgewiesen, mit besonders schweren Folgen für die anscheinend sensibelste Wirtsart, den Feuersalamander (Salamandra salamandra). Während für Deutschland neben dem Ruhrgebiet mehrere befallene Populationen in der Nordeifel (Nordrhein-Westfalen) bekannt sind, war der Hautpilz in Rheinland-Pfalz bisher noch nicht nachgewiesen. Bei früheren Präsenz-Absenz-Kartierungen (2015-2016) des Feuersalamanders wurde bereits eine auffällige Verbreitungslücke mit ehemals bekannten Vorkommen im nordwestlichen Teil der rheinland-pfälzischen Eifel festgestellt (im Bereich des Mittelgebirgszuges "Schneifel"), welche durch eine Larvenerfassung im Jahre 2018 in der gesamten Grenzregion zu Nordrhein-Westfalen bestätigt wurde. Auch der Vergleich mit dem Verbreitungsmuster der Art in einer entfernten, offensichtlich noch nicht von der Salamanderpest betroffenen Region (Hunsrück, Moseltal), legt nahe, dass die in der Schneifel nicht mehr auffindbaren Populationen durch die Salamanderpest ausgelöscht oder zumindest stark reduziert wurden. Es wurden in den Jahren 2015-2018 Hautabstriche von Feuersalamandern und - v.a. wenn diese nicht auffindbar waren - Molchen und Froschlurchen genommen. Durch molekularbiologische Analysen konnte so erstmalig in Rheinland-Pfalz der Erreger der Salamanderpest an parasitierten Berg- (Ichthyosaura alpestris) und Fadenmolchen (Lissotriton helveticus) von insgesamt fünf Standorten festgestellt werden. Drei dieser Standorte befinden sich inmitten der beobachteten Verbreitungslücke des Feuersalamanders in der Schneifel und bestätigen die Vermutung eines dort bereits sichtbaren Effekts der Krankheit. Ein vierter Standort mit infizierten Berg- und Fadenmolchen befindet sich jedoch etwa 15 km Luftlinie von der Schneifel, weiter östlich bei Duppach in der Nähe von Gerolstein, und zudem wurde an Bergmolchen etwa 20 km Luftlinie südlich (Raum Plütscheid, nahe Bitburg) der bisher südlichste Verbreitungspunkt der Salamanderpest in seinem invasiven mitteleuropäischen Areal entdeckt. In diesem zusammenhängenden Waldgebiet werden seit 2015 jährlich die Salamanderlarven-Populationen in drei Mittelgebirgsbächen erfasst. Die Fangzahlen sind seither teils drastisch zusammengebrochen und bei nächtlichen Begehungen konnten hier fast keine oder keine Adulti zur Beprobung aufgefunden werden, was nahe legt, dass auch hier die Salamanderpest bereits die Lokalpopulationen stark reduziert hat. Somit ist die Salamanderpest auf Grundlage eines "minimum convex polygons" nun in einem ca. 170 km² großen Bereich in Rheinland-36 Pfalz bekannt. Neben dem Feuersalamander, der von der Salamanderpest am schlimmsten betroffen scheint, sind auch die Infektionen einheimischer Molche beunruhigend. Bisher konnten zwar in Rheinland-Pfalz noch keine an dem Pathogen verendeten Molche oder eindeutige Be-standsrückgänge von Molchpopulationen nachgewiesen werden, jedoch deuten ein an dem Pathogen verendeter Kammmolch (Triturus cristatus), Totfunde zersetzter Bergmolche und anekdotische Berichte von Bestandsrückgängen in der nordrhein-westfälischen Eifel auf negative Effekte der Salamanderpest auf Molche hin. Die Langzeiteffekte auf Salamander- als auch Molchpopulationen sowie die Entwicklung von Handlungsempfehlungen, um eine weitere Ausbreitung der Salamanderpest zumindest zu verzögern, bleiben weiterhin Forschungsschwerpunkte von besonderer Relevanz für den Amphibienschutz.

Amphibians, the most severely declining vertebrate class, are especially threatened by pathogenic chytrid fungi. Batrachochytrium salamandrivorans (Bsal) was most likely introduced from Asia to Europe. Here, it causes mortal skin diseases (chytridiomycosis) and Bsal-caused mass mortalities in fire salamanders (Salamandra salamandra). Individuals of this species usually die shortly after infection. Hence, this disease is also called ‘salamander plague’. In Germany, Bsal caused strong population declines of fire salamanders in the northern Eifel and the Ruhr area (both North Rhine-Westphalia). A spread within the southern Eifel (Rhineland-Palatinate) is currently observed, probably causing a silent disappearance of fire salamander populations. Bsal can also lead to chytridiomycosis in newts, but animals can survive an infection, dependent on intensity and species. However, newts can thus spread Bsal as reservoirs outside the fire salamander’s range. So far, the observations in the wild indicate complex infection courses, and population effects are difficult to predict.

Infektionskrankheiten werden als eine der Hauptursachen des alarmierenden globalen Rückgangs von Amphibien angesehen. Seit Jahrzehnten verursacht der Amphibien-Hautpilz Batrachochytrium dendrobatidis (Bd) weltweit dramatische Bestandseinbrüche und -verluste, während ein weiterer Amphibien-Hautpilz namens Batrachochytrium salamandrivorans (Bsal) erst seit Kurzem die Aufmerksamkeit in Mitteleuropa auf sich zieht. Bsal wirkt sich verheerend auf unsere heimischen Salamander und Molche aus und hat bereits bei Feuersalamandern (Salamandra salamandra) zu Massensterben geführt, weshalb auch von der Salamanderpest gesprochen wird. Seit 2015 ist Bsal auch in Nordrhein-Westfalen nachgewiesen.

Escalating occurrences of emerging infectious diseases underscore the importance of understanding microbiome-pathogen interactions. The amphibian cutaneous microbiome is widely studied for its potential to mitigate disease-mediated amphibian declines. Other microbial interactions in this system, however, have been largely neglected in the context of disease outbreaks. European fire salamanders have suffered dramatic population crashes as a result of the newly emerged Batrachochytrium salamandrivorans (Bsal). In this paper, we investigate microbial interactions on multiple fronts within this system. We show that wild, healthy fire salamanders maintain complex skin microbiotas containing Bsal-inhibitory members, but these community are present at a remarkably low abundance. Through experimentation, we show that increasing bacterial densities of Bsal-inhibiting bacteria via daily addition slowed disease progression in fire salamanders. Additionally, we find that experimental-Bsal infection elicited subtle changes in the skin microbiome, with selected opportunistic bacteria increasing in relative abundance resulting in septicemic events that coincide with extensive destruction of the epidermis. These results suggest that fire salamander skin, in natural settings, maintains bacterial communities at numbers too low to confer sufficient protection against Bsal, and, in fact, the native skin microbiota can constitute a source of opportunistic bacterial pathogens that contribute to pathogenesis. By shedding light on the complex interaction between the microbiome and a lethal pathogen, these data put the interplay between skin microbiomes and a wildlife disease into a new perspective.

One of the most important factors driving amphibian declines worldwide is the infectious disease, chytridiomycosis. Two fungi have been associated with this disease, Batrachochytrium dendrobatidis and B. salamandrivorans (Bsal). The latter has recently driven Salamandra salamandra populations to extirpation in parts of the Netherlands, and Belgium, and potentially also in Germany. Bsal has been detected in the pet trade, which has been hypothesized to be the pathway by which it reached Europe, and which may continuously contribute to its spread. In the present study, 918 amphibians belonging to 20 captive collections in Germany and Sweden were sampled to explore the extent of Bsal presence in captivity. The fungus was detected by quantitative Polymerase Chain Reaction (qPCR) in ten collections, nine of which lacked clinical symptoms. 23 positives were confirmed by independent processing of duplicate swabs, which were analysed in a separate laboratory, and/or by sequencing ITS and 28 S gene segments. These asymptomatic positives highlight the possibility of Bsal being widespread in captive collections, and is of high conservation concern. This finding may increase the likelihood of the pathogen being introduced from captivity into the wild, and calls for according biosecurity measures. The detection of Bsal-positive alive specimens of the hyper-susceptible fire salamander could indicate the existence of a less aggressive Bsal variant or the importance of environmental conditions for infection progression.

Epidemiology relies on understanding the distribution of pathogens which often can be detected through DNA-based techniques, such as quantitative Polymerase Chain Reaction (qPCR). Typically, the DNA of each individual sample is separately extracted and undergoes qPCR analysis. However, when performing field surveys and long-term monitoring, a large fraction of the samples is generally expected to be negative, especially in geographical areas still considered free of the pathogen. If pathogen detection within a population – rather than determining its individual prevalence – is the focus, work load and monetary costs can be reduced by pooling samples for DNA extraction. We test and refine a user-friendly technique where skin swabs can be pooled during DNA extraction to detect the amphibian chytrid fungi, Batrachochytrium dendrobatidis and B.salamandrivorans (Bsal). We extracted pools with different numbers of samples (from one to four swabs), without increasing reaction volumes, and each pool had one sample inoculated with a predetermined zoospore amount. Pool size did not reduce the ability to detect the two fungi, except if inoculated with extremely low zoospore amounts (one zoospore). We confirm that pooled DNA extraction of cutaneous swabs can substantially reduce processing time and costs without minimizing detection sensitivity. This is of relevance especially for the new emerging pathogen Bsal, for which pooled DNA extraction had so far not been tested and massive monitoring efforts in putatively unaffected regions are underway.

The emergence of the chyrrid fungus Batrachochytriutn salamandrivorans (Bsal) represents a dramatic new threat to European amphibians. This skin pathogen causes skin lesions and ulcerations in European salamanders, eventually causing their death. Bsal first emerged in the Netherlands and Belgium where it caused mass mortality in populations of fire salamanders (Salamandra salamandra). As the affected sites were situated at less than 10 km distance from the German border, the occurrence of the pathogen was also to be expected in the adjacent Eifel region in Germany. Monitoring work to elucidate the possible occurrence of Bsal in Germany was started in 2014 by the universities of Trier and Braunschweig, along with the Biological Stations in Diiren and Aachen. Salamanders and newts were systematically swabbed and screened for Bsal in the Northern (in the state of North Rhine-Westphalia, NRW) and Southern Eifel (Rhineland-Palatinate, RP). The sampling was complemented by 186 fire salamander swabs from other parts of NRW, Lower Saxony and Thuringia. While Bsal could not yet be detected in 2014, positive individuals were found at no less than four sites in the Northern Eifel in 2015. This number increased in the Northern Eifel to ten in 2017, distributed over almost the entire study region. At three further sites with formerly large fire salamander populations, almost no individuals could be observed in the study period, providing evidence for drastic declines. Besides fire salamanders, Bsal-infected individuals were also found for all newt species in the Northern Eifel and adjacent areas north of it (Ichthyosaura alpestris, Lissotriton helveticus, L. vulgaris, Triturus cristatus), partly in sites outside of the range of fire salamanders. In the Southern Eifel, no Bsal-positives were detected, but at numerous sites where fire salamander populations had been recorded in the 1990s, neither adults nor larvae could be found. Furthermore, in 2017, a second outbreak was confirmed around the city of Essen (in NRW, but> 70 km from the Eifel), including massive fire salamander mortality events, and it is unknown how the pathogen has reached this area. Clearly Bsal is on its way to become one of strongest and most imminent threats to the amphibian diversity of Europe. By expected range expansions from its current nuclei in the Netherlands, Belgium and Germany, but also driven by amphibian imports from its probable native range in Asia, this fungus might well push numerous populations and even species of newts and salamanders Europe-wide over the brink to extinction. To avoid such range expansions to be further expedited, field biologists are urged to keep to recommended hygiene standards, and to consider the danger of spreading this pathogen when translocating or reintroducing amphibians. We also call for immediate implementation of a better regulation of the amphibian trade, specifically for Germany, in order to ensure adequate quarantine, screening and treatment of imported amphibians.

Lack of disease spill-over between adjacent populations has been associated with habitat fragmentation and the absence of population connectivity. We here present a case which describes the absence of the spill-over of the chytrid fungus Batrachochytrium salamandrivorans (Bsal) between two connected subpopulations of fire salamanders (Salamandra salamandra). Based on neutrally evolving microsatellite loci, both subpopulations were shown to form a single genetic cluster, suggesting a shared origin and/or recent gene flow. Alpine newts (Ichthyosaura alpestris) and fire salamanders were found in the landscape matrix between the two sites, which are also connected by a stream and separated by no obvious physical barriers. Performing a laboratory trial using alpine newts, we confirmed that Bsal is unable to disperse autonomously. Vector-mediated dispersal may have been impeded by a combination of sub-optimal connectivity, limited dispersal ability of infected hosts and a lack of suitable dispersers following the rapid, Bsal-driven collapse of susceptible hosts at the source site. Although the exact cause remains unclear, the aggregate evidence suggests that Bsal may be a poorer disperser than previously hypothesized. The lack of Bsal dispersal between neighbouring salamander populations opens perspectives for disease management and stresses the necessity of implementing biosecurity measures preventing human-mediated spread.

The emergence of the chytrid fungus Batrachochytrium salamandrivorans (Bsal) represents a dramatic new threat to European amphibians. This skin pathogen causes skin lesions and ulcerations in European salamanders, eventually causing their death. Bsal first emerged in the Netherlands and Belgium where it caused mass mortality in populations of fire salamanders (Salamandra salamandra). As the affected sites were situated at less than 10 km distance from the German border, the occurrence of the pathogen was also to be expected in the adjacent Eifel region in Germany. Monitoring work to elucidate the possible occurrence of Bsal in Germany was started in 2014 by the universities of Trier and Braunschweig, along with the Biological Stations in Düren and Aachen. Salamanders and newts were systematically swabbed and screened for Bsal in the Northern (in the state of North Rhine-Westphalia, NRW) and Southern Eifel (Rhineland-Palatinate, RP). The sampling was complemented by 186 fire salamander swabs from other parts of NRW, Lower Saxony and Thuringia. While Bsal could not yet be detected in 2014, positive individuals were found at no less than four sites in the Northern Eifel in 2015. This number increased in the Northern Eifel to ten in 2017, distributed over almost the entire study region. At three further sites with formerly large fire salamander populations, almost no individuals could be observed in the study period, providing evidence for drastic declines. Besides fire salamanders, Bsal-infected individuals were also found for all newt species in the Northern Eifel and adjacent areas north of it (Ichthyosaura alpestris, Lissotriton helveticus, L. vulgaris, Triturus cristatus), partly in sites outside of the range of fire salamanders. In the Southern Eifel, no Bsal-positives were detected, but at numerous sites where fire salamander populations had been recorded in the 1990s, neither adults nor larvae could be found. Furthermore, in 2017, a second outbreak was confirmed around the city of Essen (in NRW, but > 70 km from the Eifel), including massive fire salamander mortality events, and it is unknown how the pathogen has reached this area. Clearly Bsal is on its way to become one of strongest and most imminent threats to the amphibian diversity of Europe. By expected range expansions from its current nuclei in the Netherlands, Belgium and Germany, but also driven by amphibian imports from its probable native range in Asia, this fungus might well push numerous populations and even species of newts and salamanders Europewide over the brink to extinction. To avoid such range expansions to be further expedited, field biologists are urged to keep to recommended hygiene standards, and to consider the danger of spreading this pathogen when translocating or reintroducing amphibians. We also call for immediate implementation of a better regulation of the amphibian trade, specifically for Germany, in order to ensure adequate quarantine, screening and treatment of imported amphibians

Emerging infectious diseases cause extirpation of wildlife populations. We use an epidemiological model to explore the effects of a recently emerged disease caused by the salamander-killing chytrid fungus Batrachochytrium salamandrivorans (Bsal) on host populations, and to evaluate which mitigation measures are most likely to succeed. As individuals do not recover from Bsal, we used a model with the states susceptible, latent and infectious, and parametrized the model using data on host and pathogen taken from the literature and expert opinion. The model suggested that disease outbreaks can occur at very low host densities (one female per hectare). This density is far lower than host densities in the wild. Therefore, all naturally occurring populations are at risk. Bsal can lead to the local extirpation of the host population within a few months. Disease outbreaks are likely to fade out quickly. A spatial variant of the model showed that the pathogen could potentially spread rapidly. As disease mitigation during outbreaks is unlikely to be successful, control efforts should focus on preventing disease emergence and transmission between populations. Thus, this emerging wildlife disease is best controlled through prevention rather than subsequent actions.

1. Conservation science can be most effective in its decision-support role when seeking answers to clearly formulated questions of direct management relevance. Emerging wildlife diseases, a driver of global biodiversity loss, illustrate the challenges of performing this role: in spite of considerable research, successful disease mitigation is uncommon. Decision analysis is increasingly advocated to guide mitigation planning, but its application remains rare. 2. Using an integral projection model, we explored potential mitigation actions for avoiding population declines and the ongoing spatial spread of the fungus Batrachochytrium salamandrivorans (Bsal). This fungus has recently caused severe amphibian declines in north-western Europe and currently threatens Palearctic salamander diversity. 3. Available evidence suggests that a Bsal outbreak in a fire salamander (Salamandra salamandra) population will lead to its rapid extirpation. Treatments such as antifungals or probiotics would need to effectively interrupt transmission (reduce probability of infection by nearly 90%) in order to reduce the risk of host extirpation and successfully eradicate the pathogen. 4. Improving the survival of infected hosts is most likely to be detrimental as it increases the potential for pathogen transmission and spread. Active removal of a large proportion of the host population has some potential to locally eradicate Bsal and interrupt its spread, depending on the presence of Bsal reservoirs and on the host's spatial dynamics, which should therefore represent research priorities. 5. Synthesis and applications. Mitigation of Batrachochytrium salamandrivorans epidemics in susceptible host species is highly challenging, requiring effective interruption of transmission and radical removal of host individuals. More generally, our study illustrates the advantages of framing conservation science directly in the management decision context, rather than adapting to it a posteriori.

Seit mindestens 2010 tritt in den Niederlanden ein neuer Amphibien-Chytridpilz auf, der inzwischen auch in Belgien nachgewiesen wurde. Batrachochytrium salamandrivorans (Bs) befällt nur Schwanzlurche und könnte eine Bedrohung für einheimische Arten werden. Der anscheinend aus Asien stammende Pilz verursachte starke Einbrüche der befallenen Feuersalamander-Populationen. Für Molche liegen keine verlässlichen Daten vor. Im Labor konnten jedoch Kamm- und Bergmolch infiziert werden, während der Fadenmolch anscheinend resistent ist (Martel et al. 2014).

The emerging infectious disease chytridiomycosis is one of the major factors triggering global amphibian declines. A recently discovered species of chytrid fungus, Batrachochytrium salamandrivorans( Bsal), likely originated in East Asia, has led to massive declines in populations of fire salamanders ( Salamandra salamandra) after its apparent introduction to the Netherlands and Belgium. Here, we report the first detection of this pathogen in Germany where it caused mass mortality of fire salamanders in a captive collection. Salamanders from this collection showed an almost 100% prevalence of infection with Bsal. Supposed Bsal-induced mortality occurred in multiple Salamandraspecies ( S. salamandra, S. algira, S. corsica, and S. infraimmaculata), while Bsalinfection was confirmed in nine subspecies of S. salamandraand in S. algira. Our study indicates that this pathogen can potentially infect all fire salamander species and subspecies. If Bsalspreads from captive collections to wild populations, then a similar devastating effect associated with high mortality should be expected.

The chytrid fungus Batrachochytrium salamandrivorans (Bsal) is a dangerous pathogen to salamanders and newts. Apparently native to Asia, it has recently been detected in Western Europe where it is expected to spread and to have dramatic effects on naïve hosts. Since 2010, Bsal has led to some catastrophic population declines of urodeles in the Netherlands and Belgium. More recently, it has been discovered in additional, more distant sites including sites in Germany. With the purpose to contribute to a better understanding of Bsal, we modelled its potential distribution in its invasive European range to gain insights about the factors driving this distribution. We computed Bsal Maxent models for two predictor sets, which represent different temporal resolutions, using three different background extents to account for different invasion stage scenarios. Beside `classical' bioclimate, we employed weather data, which allowed us to emphasize predictors in accordance with the known pathogen's biology. The most important predictors as well as spatial predictions varied between invasion scenarios and predictor sets. The most reasonable model was based on weather data and the scenario of a recent pathogen introduction. It identified temperature predictors, which represent optimal growing conditions and heat limiting conditions, as the most explaining drivers of the current distribution. This model also predicted large areas in the study region as suitable for Bsal. The other models predicted considerably less, but shared some areas which we interpreted as most likely high risk zones. Our results indicate that growth relevant temperatures measured under laboratory conditions might also be relevant on a macroecological scale, if predictors with a high temporal resolution and relevance are used. Additionally, the conditions in our study area support the possibility of a further Bsal spread, especially when considering that our models might tend to underestimate the potential distribution of Bsal.