Amphibian Biodiversity Research Articles

After the epizootic: Host–pathogen dynamics in montane tropical amphibian communities with high prevalence of chytridiomycosis

AbstractThe amphibian fungal disease chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd), poses a great threat to global amphibian biodiversity. In Peruvian cloud forests of the Kosñipata Valley of Manu National Park where chytrid infection is highly prevalent, we have monitored species‐rich amphibian communities since 1996. An epizootic of chytridiomycosis is thought to have caused the disappearance of 35% of species richness in the early 2000s. We investigated the post‐epizootic Bd prevalence and infection intensity within the remnant amphibian community from 2008 to 2015, and modeled Bd dynamics as a function of species, season, reproductive mode, life stage, and elevation. Prevalence was higher in 2012–2015 than in 2008–2009, but overall prevalence has remained fairly constant (~50%) post‐epizootic. We also found that while prevalence decreased with elevation during the wet season, it generally increased with elevation during the dry season, potentially due to seasonal changes in temperature and precipitation. In aquatic habitats, Bd is likely maintained through a single, stream‐breeding, putative reservoir species (which survived epizootics, in contrast to other aquatic‐breeding species). The now‐dominant terrestrial‐breeding species allow Bd to persist and spread in terrestrial habitats, possibly through individual dispersal into naïve areas. We conclude that Bd prevalence in the Kosñipata Valley has stabilized over time, suggesting that Bd is now enzootic. Long‐term monitoring of host infection is important because temporal changes in prevalence and infection intensity can cause changes in host species richness and abundance, which in turn may alter the trajectory of host–pathogen dynamics.Abstract in Spanish is available with online material.

Chytrid Pathogen (Batrachochytrium dendrobatidis) in African Amphibians: A Continental Analysis of Occurrences and Modeling of Its Potential Distribution

The fungal pathogen Batrachochytrium dendrobatidis (Bd) is implicated in global declines of amphibian populations and has been documented in African specimens originally collected as far back as the 1930s. Numerous recent surveys focusing on regional pathogen prevalence have greatly increased the number of known occurrences of Bd in African species, but few studies have focused on continental distribution patterns. We analyzed all known positive occurrences of Bd in African amphibians to date, including newly reported data from Cameroon, the Democratic Republic of the Congo, Gabon, Namibia, and the Republic of the Congo. Records from both Namibia and the Republic of the Congo reported herein represent first positive occurrences for these countries. With this most comprehensive sampling of the African continent to date we identified patterns of Bd-positive occurrences associated with (1) location (i.e., biogeographic region, country), (2) taxonomy, (3) life history, and (4) threat of extinction. We used fine-grained (30 arc seconds) environmental niche models (ENMs) to predict the continental distribution of Bd and identify hotspots for the pathogen, including areas not previously modeled to have high suitability for the fungus, and areas of high amphibian biodiversity from which Bd has not yet been documented. Our ENMs predicted that the environmentally suitable range of Bd encompasses vast areas of high amphibian biodiversity, including the Congo Basin and the Albertine Rift. Although our ENMs indicated that West Africa is environmentally suitable for Bd, the fungus has not been reported west of the Dahomey Gap. Likewise, the ENMs also identified regions across the Congo Basin and coastal Angola that are environmentally suitable for the pathogen but from which Bd has not yet been reported, underscoring a need for Bd surveys in these regions. Although amphibian declines in Africa have not been directly attributed to chytridiomycosis, Bd has been detected in over one fifth of the most-threatened African amphibians. Given the presence of the hypervirulent Bd global panzootic lineage (BdGPL) in Africa, we believe that the threat of Bd as a novel pathogen may be underestimated and that focused research is urgently needed to identify which species are susceptible to Bd-driven declines.

Monitoring the Seasonal Hydrology of Alpine Wetlands in Response to Snow Cover Dynamics and Summer Climate: A Novel Approach with Sentinel-2

Climate change in the European Alps during recent years has led to decreased snow cover duration as well as increases in the frequency and intensity of summer heat waves. The risk of drought for alpine wetlands and temporary pools, which rely on water from snowmelt and provide habitat for specialist plant and amphibian biodiversity, is largely unknown and understudied in this context. Here, we test and validate a novel application of Sentinel-2 imagery aimed at quantifying seasonal variation in water surface area in the context of 95 small (median surface area <100 m2) and shallow (median depth of 20 cm) alpine wetlands in the French Alps, using a linear spectral unmixing approach. For three study years (2016–2018), we used path-analysis to correlate mid-summer water surface area to annual metrics of snowpack (depth and duration) and spring and summer climate (temperature and precipitation). We further sought to evaluate potential biotic responses to drought for study years by monitoring the survival of common frog (Rana temporaria) tadpoles and wetland plant biomass production quantified using peak Normalized Difference Vegetation Index (NDVI). We found strong agreement between citizen science-based observations of water surface area and Sentinel-2 based estimates (R2 = 0.8–0.9). Mid-summer watershed snow cover duration and summer temperatures emerged as the most important factors regulating alpine wetland hydrology, while the effects of summer precipitation, and local and watershed snow melt-out timing were not significant. We found that a lack of summer snowfields in 2017 combined with a summer heat wave resulted in a significant decrease in mid-summer water surface area, and led to the drying up of certain wetlands as well as the observed mortality of tadpoles. We did not observe a negative effect of the 2017 summer on the biomass production of wetland vegetation, suggesting that wetlands that maintain soil moisture may act as favorable microhabitats for above treeline vegetation during dry years. Our work introduces a remote sensing-based protocol for monitoring the surface hydrology of alpine wetland habitats at the regional scale. Given that climate models predict continued reduction of snow cover in the Alps during the coming years, as well as particularly intense warming during the summer months, our conclusions underscore the vulnerability of alpine wetlands in the face of ongoing climate change.

Biodiversity of Amphibians in Pakistan, causes of their decline and their conservation

Objectives: The present study was conducted to review the biodiversity of Amphibians, their decline in population and conservation. Methods/Statistical analysis: This study was done by reviewing the previous papers on biodiversity of Amphibians and available literature on various search engines. Findings: Species of amphibians estimated worldwide reveals 7481 species consisting of three orders, Salientia (Anura), Urodela (Caudata) and Apoda (Gymnophiona). The Salientia contains 6577, Urodela (Caudata) entail 698 species of both land and aquatic inhabitants and Apoda (Gymnophiona) virtually blind and nonmotile animals include 206 species. However, the population of Amphibians is reduced in Pakistan because of dry conditions and is a prominent indicator of climatic change. In Pakistan, the dominating population of Amphibians is Salientia (Anura), consisting of 21 species, 12 genera, and 4 families. Due to anthropogenic activities like the use of pesticides and fertilizers, deforestation, pollution, fragmentation and urbanization affects the amphibians. For conservation and protection, serious initiatives may be mediated to manage the situation. Application/Improvements: The present study will be helpful to conserve the diversity of Amphibians in the region and present findings may be useful in future studies. Keywords: Amphibia; Pakistan; Decline; conservation; Population

Amphibian species diversity in the proposed extension of the Bukit Teraja Protection Forest, Brunei Darussalam

Amphibian species diversity was investigated within the lowland mixed-dipterocarp forest of the proposed extension of the Bukit Teraja Protection Forest (BTPF), Brunei Darussalam in north-west Borneo. A combination of both visual encounter and acoustic sampling techniques were conducted opportunistically as well as in six selected stream transects, each containing five 5x10m plots. A total of 39 species of frogs from seven families (Bufonidae, Ceratobatrachidae, Dicroglossidae, Megophryidae, Microhylidae, Ranidae, and Rhacophoridae) were identified from the BTPF. Most notably, four new records for Brunei were discovered: Hylarana nicobariensis, Kaloula baleata, Limnonectes malesianus, and Microhyla perparva. This brings the total number of amphibian species in Brunei Darussalam to 84. Canonical correspondence analysis showed that out of 13 measured environmental variables maximum stream depth and % soil/sand of ground cover were significantly correlated with anuran assemblage composition. Species overlap between the proposed extension of the Bukit Teraja Protection Forest and the Ulu Temburong National Park (UTNP) determined by the coefficient of biogeographic resemblance (CBR) showed low species complementarity between these two regions. This emphasizes the need to upgrade the proposed extension of the BTPF to a protection forest to ensure the conservation of regional amphibian biodiversity.

Amphibian responses to livestock use of wetlands: new empirical data and a global review.

Pastureland currently occupies 26% of Earth's ice-free land surface. As the global human population continues to increase and developing countries consume more protein-rich diets, the amount of land devoted to livestock grazing will only continue to rise. To mitigate the loss of global biodiversity as a consequence of the ever-expanding amount of land converted from native habitat into pastureland for livestock grazing, an understanding of how livestock impact wildlife is critical. While previous reviews have examined the impact of livestock on a wide variety of taxa, there have been no reviews examining how global livestock grazing affects amphibians. We conducted both an empirical study in south-central Florida examining the impact of cattle on amphibian communities and a quantitative literature review of similar studies on five continents. Our empirical study analyzed amphibian community responses to cattle as both a binary (presence/absence) variable, and as a continuous variable based on cow pie density. Across all analyses, we were unable to find any evidence that cattle affected the amphibian community at our study site. The literature review returned 46 papers that met our criteria for inclusion. Of these studies, 15 found positive effects of livestock on amphibians, 21 found neutral/mixed effects, and 10 found negative effects. Our quantitative analysis of these data indicates that amphibian species that historically occurred in closed-canopy habitats are generally negatively affected by livestock presence. In contrast, open-canopy amphibians are likely to experience positive effects from the presence of livestock, and these positive effects are most likely to occur in locations with cooler climates and/or greater precipitation seasonality. Collectively, our empirical work and literature review demonstrate that under the correct conditions well-managed rangelands are able to support diverse assemblages of amphibians. These rangeland ecosystems may play a critical role in protecting future amphibian biodiversity by serving as an "off-reserve" system to supplement the biodiversity conserved within traditional protected areas.

A highly invasive chimeric ranavirus can decimate tadpole populations rapidly through multiple transmission pathways

A consequence of genetic recombination can be the evolution of highly virulent pathogen strains. Virulence can manifest through various mechanisms of host–pathogen interaction that facilitate transmission. We discovered a highly virulent chimeric ranavirus in Georgia, USA, estimated transmission parameters using controlled experiments, and developed compartmental disease models to examine potential consequences on tadpoles of a susceptible host species (Lithobates sylvaticus). Our models included three transmission pathways: direct transmission via host contact, environmental transmission via shed virions in water, and transmission via necrophagy of morbid individuals. Unlike previous models, we categorized individuals into multiple stages of infection (susceptible, latency, and infectious), where the probability of disease-induced mortality increased throughout the duration of infection following a gamma distribution with an integer shape parameter. Our simulations showed that accounting for pathogen incubation improved model predictions when compared to survival data from controlled experiments. We found that transmission due to direct contact of tadpoles was the dominant transmission pathway; however, environmental transmission played a larger role as tadpole density increased and the epidemic progressed. Estimated R0 (basic reproduction number) values >570 for all transmission pathways indicate that targeting only one transmission pathway is unlikely to thwart invasion. Additionally, the high invasion potential and diseased-induced mortality associated with this chimeric ranavirus indicate that this pathogen is a substantial threat to amphibian biodiversity in the United States.

Epigenomic changes in the túngara frog (Physalaemus pustulosus): possible effects of introduced fungal pathogen and urbanization

Amphibian populations are being threatened by human related activities including the spread of the fungal pathogen, Batrachochytrium dendrobatidis (Bd) and urbanization. With growing losses in global amphibian biodiversity, it is essential to document how amphibian populations are responding to rapid environmental changes. While most evolutionary processes, e.g. changes in allelic frequencies, may be too slow to allow adequate response to environmental changes, epigenetic modifications can rapidly translate environmental changes into adaptive phenotypic responses. Epigenetic modifications come in multiple, non-exclusive forms, the most notable being DNA methylation. Here we sought to examine variation in the frequency of DNA methylation among four tungara frog populations distributed across Gamboa, Panama; which vary in both their level of fungal presence/prevalence and urbanization. DNA samples were collected from amplexed (male–female) pairs and frequency of DNA methylation was analyzed using a methylation-sensitive amplified fragment length polymorphism protocol. We found significant variation in DNA methylation among populations, and correlations between Bd infection status and methylation patterns. Urbanization, however, had no influences on the frequency of DNA methylation. These data suggest epigenetic modifications are substantially flexible across fine-scale, environmental gradients and there appears to be possible biologically relevant links between DNA methylation and Bd infection status. Our results provide a basis for future work investigating the causal role epigenetics have in mediating phenotypic response to human-induced, environmental changes.

Ecological correlates of extinction risk in Chinese amphibians

AbstractAimChina is one of the countries with the richest amphibian biodiversity in the world. Among the 408 Chinese amphibians, 174 species are considered threatened according to the China Biodiversity Red List in 2015. However, to date, which species traits or extrinsic factors are correlated with extinction risk in Chinese amphibians is rarely examined. The aims of this study were thus to identify the patterns and correlates of extinction risk in Chinese amphibians and to determine whether patterns and processes are similar between species with either small or large geographic distributions.LocationChina.MethodsWe obtained twelve species traits and four extrinsic factors that have been commonly linked to the extinction risk of amphibians. After phylogenetic correction, these factors were tested separately and in combination to identify their correlations with extinction risk in all Chinese amphibians, and in small‐ranged and large‐ranged species.ResultsGeographic range size and elevational range were the most important predictors of extinction risk in all Chinese amphibians. Although extinction risk in small‐ranged amphibians was predominantly determined by small elevational range, in large‐ranged amphibians it was driven by geographic and elevational ranges, body size, human exploitation index and adult microhabitat. Small‐ranged amphibians had a higher percentage of threatened species than large‐ranged species. However, the body size distributions were not statistically different between these two amphibian subgroups.Main conclusionsOur findings suggest that conservation priority should be given to species with small geographic and elevational ranges. Small‐ranged and large‐ranged amphibians should be conserved with different strategies because the factors influencing extinction risk differ between these two groups. In specific, the reduction of habitat loss should be a primary focus of management efforts because species with small geographic and elevational ranges are particually vulnerable to habitat loss. Conservation efforts should also focus on protecting large‐bodied species and preventing human overexploitation for the effective conservation of large‐ranged amphibians.

Lethal toxicity of the herbicides acetochlor, ametryn, glyphosate and metribuzin to tropical frog larvae.

Despite the high amphibian biodiversity and increasing pesticide use in tropical countries, knowledge on the sensitivity of tropical amphibians to pesticides remains limited. The aim of this study was to evaluate the acute toxicity of the active ingredients of four of the main herbicides used in Brazilian sugarcane production to tadpoles of two tropical frog species: Physalaemus cuvieri and Hypsiboas pardalis. The calculated 96 h-LC50 (median lethal concentration; in mg a.s./L) values for P. cuvieri and H. pardalis were 4.4 and 7.8 (acetochlor); 15 and <10 (ametryn); 115 and 106 (glyphosate); and 85 and 68 (metribuzin), respectively. These toxicity values demonstrated little interspecies variation and the toxicity of the herbicides appeared to be at least partly related with the respective octanol-water coefficient. Published acute toxicity data of fish and amphibians for herbicides were also compiled from the US-EPA ECOTOX database. These data indicated little difference in herbicide sensitivity between tropical amphibians and both non-tropical amphibians and fish. These findings indicate that temperate (fish and amphibian) herbicide toxicity data are also protective for tropical amphibians. Constraints in such extrapolations and indications for future research are discussed.

Sperm collection and storage for the sustainable management of amphibian biodiversity

Current rates of biodiversity loss pose an unprecedented challenge to the conservation community, particularly with amphibians and freshwater fish as the most threatened vertebrates. An increasing number of environmental challenges, including habitat loss, pathogens, and global warming, demand a global response toward the sustainable management of ecosystems and their biodiversity. Conservation Breeding Programs (CBPs) are needed for the sustainable management of amphibian species threatened with extinction. CBPs support species survival while increasing public awareness and political influence. Current CBPs only cater for 10% of the almost 500 amphibian species in need. However, the use of sperm storage to increase efficiency and reliability, along with an increased number of CBPs, offer the potential to significantly reduce species loss. The establishment and refinement of techniques over the last two decades, for the collection and storage of amphibian spermatozoa, gives confidence for their use in CBPs and other biotechnical applications. Cryopreserved spermatozoa has produced breeding pairs of frogs and salamanders and the stage is set for Lifecycle Proof of Concept Programs that use cryopreserved sperm in CBPs along with repopulation, supplementation, and translocation programs. The application of cryopreserved sperm in CBPs, is complimentary to but separate from archival gene banking and general cell and tissue storage. However, where appropriate amphibian sperm banking should be integrated into other global biobanking projects, especially those for fish, and those that include the use of cryopreserved material for genomics and other research. Research over a broader range of amphibian species, and more uniformity in experimental methodology, is needed to inform both theory and application. Genomics is revolutionising our understanding of biological processes and increasingly guiding species conservation through the identification of evolutionary significant units as the conservation focus, and through revealing the intimate relationship between evolutionary history and sperm physiology that ultimately affects the amenability of sperm to refrigerated or frozen storage. In the present review we provide a nascent phylogenetic framework for integration with other research lines to further the potential of amphibian sperm banking.

Unexpected spatial population ecology of a widespread terrestrial salamander near its southern range edge.

Under the current amphibian biodiversity crisis, common species provide an opportunity to measure population dynamics across a wide range of environmental conditions while examining the processes that determine abundance and structure geographical ranges. Studying species at their range limits also provides a window for understanding the dynamics expected in future environments under increasing climate change and human modification. We quantified patterns of seasonal activity, density and space use in the eastern red-backed salamander (Plethodon cinereus) near its southern range edge and compare the spatial ecology of this population to previous findings from the core of their range. This southern population shows the expected phenology of surface activity based on temperature limitations in warmer climates, yet maintains unexpectedly high densities and large home ranges during the active season. Our study suggests that ecological factors known to strongly affect amphibian populations (e.g. warm temperature and forest fragmentation) do not necessarily constrain this southern population. Our study highlights the utility of studying a common amphibian as a model system for investigating population processes in environments under strong selective pressure.

Growth Regulation in Amphibian Pathogenic Chytrid Fungi by the Quorum Sensing Metabolite Tryptophol.

Amphibians face many threats leading to declines and extinctions, but the chytrid fungal skin pathogens Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal) have been identified as the causative factors leading to one of the greatest disease-driven losses of amphibian biodiversity worldwide. Infection may lead to different clinical outcomes, and lethal infections are commonly associated with unrestricted, exponential fungal growth in the amphibian epidermis. Mechanisms underpinning Bd and Bsal growth in the amphibian host are poorly understood. Here, we describe a quorum sensing mechanism that allows cell-to-cell communication by Bd and Bsal in order to regulate fungal densities and infection strategies. Addition of chytrid culture supernatant to chytrid cultures resulted in a concentration-dependent growth reduction and using dialysis, small metabolites were shown to be the causative factor. U-HPLC-MS/MS and in vitro growth tests identified the aromatic alcohol tryptophol as a key metabolite in regulating fungal growth. We determined tryptophol kinetics in both Bd and Bsal and confirmed the autostimulatory mode of action of this quorum sensing metabolite. Finally, we linked expression of genes that might be involved in tryptophol production, with in vitro and in vivo chytrid growth. Our results show that Bd and Bsal fungi use tryptophol to act as multicellular entities in order to regulate their growth.

Occupancy modelling reveals a highly restricted and fragmented distribution in a threatened montane frog (Philoria kundagungan) in subtropical Australian rainforests

In the last several decades, habitat loss, overexploitation, invasive organisms, disease, pollution and, more recently, climate change have led to catastrophic declines in amphibian biodiversity. Montane amphibian species, particularly those with narrow distributions and specific habitat requirements are likely to be at particular risk under future climate change scenarios. Despite this, fundamental ecological data are lacking for most of these species. Philoria kundagungan is a poorly known representative of a range-restricted genus of montane amphibians from eastern Australia. Using an occupancy framework, we conducted repeated call playback surveys at 32 sites across the mountainous regions of south-east Queensland and north-eastern New South Wales, Australia, to investigate: (1) the current extent of this species’ geographic range, and (2) environmental predictors of this species’ presence. We found that P. kundagungan has a highly restricted and fragmented distribution, being limited to ~11 km2 of potentially suitable habitat, and that its presence is strongly associated with high elevation (&amp;gt;800 m). Our survey protocol resulted in a high probability of detection (&amp;gt;70%) at occupied sites from relatively few visits. From these baseline data, future studies will have the ability to determine changes in this species’ geographic range and occupancy rate in response to the ever-increasing threats faced by P. kundagungan, thereby supporting more effective conservation strategies and policy decisions.

The effects of water and bottom sediments from Lake Balkash (Central Asia) on early development of fish and amphibians

The effects of water and bottom sediments from Lake Balkash (Central Asia) on early development of fish and amphibians

Novel quantitative PCR assay specific for the emerging Perkinsea amphibian pathogen reveals seasonal infection dynamics.

Amphibians are suffering from large-scale population declines worldwide, and infectious diseases are a central driving force. Most pathogen-mediated declines are attributed to 2 pathogens, the fungus Batrachochytrium dendrobatidis and iridoviruses in the genus Ranavirus. However, another emerging pathogen within Perkinsea is associated with mass mortality events in anurans throughout the southeastern USA. Molecular resources for detecting amphibian Perkinsea have been limited to general protistan primers that amplify a range of organisms, not all of which are disease agents. Moreover, the only quantitative method available involves histopathology, which is labor intensive, requires destructive sampling, and lacks sensitivity. Here, we developed a novel quantitative (q)PCR assay that is sensitive and specific for amphibian Perkinsea, providing a resource for rapid and reliable pathogen diagnosis. We used histopathology to confirm that qPCR burdens track the severity of Perkinsea infections across multiple anuran tissues. We also sampled 3 natural amphibian communities in Florida, USA, to assess the prevalence and intensity of amphibian Perkinsea infections across species, seasons, tissues, and life stages. Anurans from 2 of 3 sampling locations were infected, totaling 25.1% of all individuals. Infection prevalence varied significantly among locations, seasons, species, and life stages. Infection intensity was significantly higher in larval tissues than adult tissues, and was significantly different across locations, seasons, and species. Understanding relationships between amphibian Perkinsea infection, other pathogens, and biotic and abiotic cofactors will allow us to assess what drives population declines, improving our ability to develop conservation strategies for susceptible species to reduce global amphibian biodiversity loss.

The Herpetofauna from Ilha Grande (Angra dos Reis, Rio de Janeiro, Brazil): updating species composition, richness, distribution and endemisms

Ilha Grande is a large continental island (total area of 19,300 ha) situated at the southern coast of the state of Rio de Janeiro, in southeast Brazil, within the Atlantic Forest Biome. Here we provide an update to the previous knowledge of the fauna of amphibians and reptiles occurring in Ilha Grande, based on primary data from our own fieldwork and on secondary data (from institutional collections and from the literature). We report the occurrence at Ilha Grande of a total of 74 species, being 34 amphibians (all of them anurans) and 40 reptiles (27 snakes, 11 lizards, one amphisbaenian and one crocodylian). Our survey added 14 species to the herpetofaunal list of Ilha Grande (three of amphibians and eleven of reptiles) and removed one species (the amphibian Cycloramphus fuliginosus) from the previous list. The data indicated that Ilha Grande houses a considerable portion of the Atlantic Forest amphibian and reptile diversity (ca. 6% and 19%, respectively, of the species occurring in this biome) together with high occurrence of species endemic to this biome plus a few amphibian species endemic to this island. Ilha Grande is thus an important reservoir of both biodiversity and endemism of amphibians and reptiles of the Atlantic Forest of Brazil, which highlights the importance of the conservation of the island and of its different habitats along the insular landscape.

Beyond the swab: ecosystem sampling to understand the persistence of an amphibian pathogen.

Understanding the ecosystem-level persistence of pathogens is essential for predicting and measuring host-pathogen dynamics. However, this process is often masked, in part due to a reliance on host-based pathogendetection methods. The amphibian pathogens Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal) are pathogens of global conservation concern. Despite having free-living life stages, little is known about the distribution and persistence of these pathogens outside of their amphibian hosts. We combine historic amphibian monitoring data with contemporary host- and environment-based pathogendetection data to obtain estimates of Bd occurrence independent of amphibian host distributions. We also evaluate differences in filter- and swab-based detection probability and assess inferential differences arising from using different decision criteria used to classify samples as positive or negative. Water filtration-based detection probabilities were lower than those from swabs but were > 10%, and swab-based detection probabilities varied seasonally, declining in the early fall. The decision criterion used to classify samples as positive or negative was important; using a more liberal criterion yielded higher estimates of Bd occurrence than when a conservative criterion was used. Different covariates were important when using the liberal or conservative criterion in modeling Bd detection. We found evidence of long-term Bd persistence for several years after an amphibian host species of conservation concern, the boreal toad (Anaxyrus boreas boreas), was last detected. Our work provides evidence of long-term Bd persistence in the ecosystem, and underscores the importance of environmental samples for understanding and mitigating disease-related threats to amphibian biodiversity.

A Review of the Factors That Determine Whether Stormwater Ponds Are Ecological Traps And/or High-Quality Breeding Sites for Amphibians

Stormwater ponds were originally constructed to control the quantity and quality of runoff on urban roads and highways before it was released to the environment. Often, stormwater ponds were designed in a technical feat of civil engineering, with no particular ecological or landscape objective in mind. Nevertheless, they are colonized spontaneously by diverse species, including amphibians. Through an initial review of the scientific literature, the objective of this study was to understand which factors determine that a pond can be considered as an ecological trap or a valuable breeding site fort amphibian. The first step was to question the role of the pond environment as a major factor in its colonization by amphibians, demonstrating that not all ponds are colonized by the same variety of species. The internal factors in the ponds that define them as ecological traps or sustainable breeding sites for amphibians was also considered. After confirming the functional and structural similarity between highway and urban stormwater ponds, 25 publications were compared, with study sites mostly located in Europe and North America, and concerning the colonization of stormwater ponds by amphibians in urban or highway areas. Several factors were identified that may affect the ecological viability of these basins: 1) the factors related to the shape of the ponds (inclination of the banks, materials used, etc.); 2) the biotic factors (aquatic vegetation, presence of predators, etc.); 3) the abiotic factors (luminosity, water level in the ponds, etc.); and 4) pollutants. The low number of publications on this subject, as well as the law variety in the location of study sites, only allows for cautious conclusions be drawn. In particular, stormwater ponds located in highly anthropogenic landscapes can be both ecological traps and suitable habitats for amphibian breeding. This depends on the species that colonize each pond, many internal factors, and the environmental context in which it is embedded. Additional research is therefore needed in other parts of the world - particularly in amphibian biodiversity hotspots - as well as other impact factors such as the effects of different maintenance practices.

The amphibians of the state of Rio de Janeiro, Brazil: an updated and commented list

The amphibian fauna of the state of Rio de Janeiro, in southeatern Brazil, is characterized by high species richness and rates of endemism, and is still insufficiently known. A first list of amphibian species with occurrence in the state was published in 2004 and reported 166 taxa, but since then many new records, descriptions of new taxa, and revalidations and synonymizations of species have consistently improved the knowledge about the state’s amphibian biodiversity. Thus, a review and update of that list was deemed necessary. We herein present an updated and commented list of amphibian species occurring in the state of Rio de Janeiro based on a survey of the literature. We recorded the occurrence of a total of 201 species of amphibians (197 anurans and four caecilians) in Rio de Janeiro, with 54 of them (ca. 27%) considered to be endemic of the state. Our study presents an increase in species richness of 21% since the publication of the previous list, indicating a consistent advance in knowledge of the composition of the amphibian fauna in the state. In spite of its relatively small territorial extension (total area ca. 43,800 km²), the state of Rio de Janeiro contains nearly 20% of the amphibian species known to occur in Brazil and around 40% of those occurring in the Atlantic Forest biome. Thus, that state constitutes an important reservoir of amphibian biodiversity in the Atlantic Forest biome and in Brazil, as a whole.