BIOTIC FACTORS IN AMPHIBIAN POPULATION DECLINES

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Amphibians evolved in, and continue to exist in, habitats that are replete with many other organisms. Some of these organisms serve as prey for amphibians and others interact with amphibians as predators, competitors, pathogens, or symbionts. Still other organisms in their enviro...

Status and trends of amphibian declines and extinctions worldwide.

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Stuart, Simon N; Chanson, Janice S; Cox, Neil A; Young, Bruce E; Rodrigues, Ana S L; Fischman, Debra L; Waller, Robert W

2004-12-03

The first global assessment of amphibians provides new context for the well-publicized phenomenon of amphibian declines. Amphibians are more threatened and are declining more rapidly than either birds or mammals. Although many declines are due to habitat loss and overutilization, other, unidentified processes threaten 48% of rapidly declining species and are driving species most quickly to extinction. Declines are nonrandom in terms of species' ecological preferences, geographic ranges, and taxonomic associations and are most prevalent among Neotropical montane, stream-associated species. The lack of conservation remedies for these poorly understood declines means that hundreds of amphibian species now face extinction.

Evaluation of episodic acidification and amphibian declines in the Rocky Mountains

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Frank A. Vertucci; Paul Stephen Corn

1996-01-01

We define criteria for documenting episodic acidification of amphibian breeding habitats and examine whether episodic acidification is responsible for observed declines of amphibian populations in the Rocky Mountains. Anthropogenic episodic acidification, caused by atmospheric deposition of sulfate and nitrate, occurs when the concentration of acid anions increases...

Citation rate and perceived subject bias in the amphibian-decline literature.

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Ohmer, Michel E; Bishop, Phillip J

2011-02-01

As a result of global declines in amphibian populations, interest in the conservation of amphibians has grown. This growth has been fueled partially by the recent discovery of other potential causes of declines, including chytridiomycosis (the amphibian chytrid, an infectious disease) and climate change. It has been proposed that researchers have shifted their focus to these novel stressors and that other threats to amphibians, such as habitat loss, are not being studied in proportion to their potential effects. We tested the validity of this proposal by reviewing the literature on amphibian declines, categorizing the primary topic of articles within this literature (e.g., habitat loss or UV-B radiation) and comparing citation rates among articles on these topics and impact factors of journals in which the articles were published. From 1990 to 2009, the proportion of papers on habitat loss remained fairly constant, and although the number of papers on chytridiomycosis increased after the disease was described in 1998, the number of published papers on amphibian declines also increased. Nevertheless, papers on chytridiomycosis were more highly cited than papers not on chytridiomycosis and were published in journals with higher impact factors on average, which may indicate this research topic is more popular in the literature. Our results were not consistent with a shift in the research agenda on amphibians. We believe the perception of such a shift has been supported by the higher citation rates of papers on chytridiomycosis. ©2010 Society for Conservation Biology.

Habitat split and the global decline of amphibians.

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Becker, Carlos Guilherme; Fonseca, Carlos Roberto; Haddad, Célio Fernando Baptista; Batista, Rômulo Fernandes; Prado, Paulo Inácio

2007-12-14

The worldwide decline in amphibians has been attributed to several causes, especially habitat loss and disease. We identified a further factor, namely "habitat split"-defined as human-induced disconnection between habitats used by different life history stages of a species-which forces forest-associated amphibians with aquatic larvae to make risky breeding migrations between suitable aquatic and terrestrial habitats. In the Brazilian Atlantic Forest, we found that habitat split negatively affects the richness of species with aquatic larvae but not the richness of species with terrestrial development (the latter can complete their life cycle inside forest remnants). This mechanism helps to explain why species with aquatic larvae have the highest incidence of population decline. These findings reinforce the need for the conservation and restoration of riparian vegetation.

Analysis of three amphibian populations with quarter-century long time-series.

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Meyer, A H; Schimidt, B R; Grossenbacher, K

1998-01-01

Amphibians are in decline in many parts of the world. Long tme-series of amphibian populations are necessary to distinguish declines from the often strong fluctuations observed in natural populations. Time-series may also help to understand the causes of these declines. We analysed 23-28-year long time-series of the frog Rana temporaria. Only one of the three studied populations showed a negative trend which was probably caused by the introduction of fish. Two populations appeared to be densi...

Count data, detection probabilities, and the demography, dynamics, distribution, and decline of amphibians.

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Schmidt, Benedikt R

2003-08-01

The evidence for amphibian population declines is based on count data that were not adjusted for detection probabilities. Such data are not reliable even when collected using standard methods. The formula C = Np (where C is a count, N the true parameter value, and p is a detection probability) relates count data to demography, population size, or distributions. With unadjusted count data, one assumes a linear relationship between C and N and that p is constant. These assumptions are unlikely to be met in studies of amphibian populations. Amphibian population data should be based on methods that account for detection probabilities.

Are snake populations in widespread decline?

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Reading, C J; Luiselli, L M; Akani, G C; Bonnet, X; Amori, G; Ballouard, J M; Filippi, E; Naulleau, G; Pearson, D; Rugiero, L

2010-12-23

Long-term studies have revealed population declines in fishes, amphibians, reptiles, birds and mammals. In birds, and particularly amphibians, these declines are a global phenomenon whose causes are often unclear. Among reptiles, snakes are top predators and therefore a decline in their numbers may have serious consequences for the functioning of many ecosystems. Our results show that, of 17 snake populations (eight species) from the UK, France, Italy, Nigeria and Australia, 11 have declined sharply over the same relatively short period of time with five remaining stable and one showing signs of a marginal increase. Although the causes of these declines are currently unknown, we suspect that they are multi-faceted (such as habitat quality deterioration, prey availability), and with a common cause, e.g. global climate change, at their root.

Amphibian decline and extinction: what we know and what we need to learn.

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Collins, James P

2010-11-01

For over 350 million yr, thousands of amphibian species have lived on Earth. Since the 1980s, amphibians have been disappearing at an alarming rate, in many cases quite suddenly. What is causing these declines and extinctions? In the modern era (post 1500) there are 6 leading causes of biodiversity loss in general, and all of these acting alone or together are responsible for modern amphibian declines: commercial use; introduced/exotic species that compete with, prey on, and parasitize native frogs and salamanders; land use change; contaminants; climate change; and infectious disease. The first 3 causes are historical in the sense that they have been operating for hundreds of years, although the rate of change due to each accelerated greatly after about the mid-20th century. Contaminants, climate change, and emerging infectious diseases are modern causes suspected of being responsible for the so-called 'enigmatic decline' of amphibians in protected areas. Introduced/exotic pathogens, land use change, and infectious disease are the 3 causes with a clear role in amphibian decline as well as extinction; thus far, the other 3 causes are only implicated in decline and not extinction. The present work is a review of the 6 causes with a focus on pathogens and suggested areas where new research is needed. Batrachochytrium dendrobatidis (Bd) is a chytrid fungus that is an emerging infectious disease causing amphibian population decline and species extinction. Historically, pathogens have not been seen as a major cause of extinction, but Bd is an exception, which is why it is such an interesting, important pathogen to understand. The late 20th and early 21st century global biodiversity loss is characterized as a sixth extinction event. Amphibians are a striking example of these losses as they disappear at a rate that greatly exceeds historical levels. Consequently, modern amphibian decline and extinction is a lens through which we can view the larger story of biodiversity

The cause of global amphibian declines: a developmental endocrinologist's perspective.

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Hayes, T B; Falso, P; Gallipeau, S; Stice, M

2010-03-15

Greater than 70% of the world's amphibian species are in decline. We propose that there is probably not a single cause for global amphibian declines and present a three-tiered hierarchical approach that addresses interactions among and between ultimate and proximate factors that contribute to amphibian declines. There are two immediate (proximate) causes of amphibian declines: death and decreased recruitment (reproductive failure). Although much attention has focused on death, few studies have addressed factors that contribute to declines as a result of failed recruitment. Further, a great deal of attention has focused on the role of pathogens in inducing diseases that cause death, but we suggest that pathogen success is profoundly affected by four other ultimate factors: atmospheric change, environmental pollutants, habitat modification and invasive species. Environmental pollutants arise as likely important factors in amphibian declines because they have realized potential to affect recruitment. Further, many studies have documented immunosuppressive effects of pesticides, suggesting a role for environmental contaminants in increased pathogen virulence and disease rates. Increased attention to recruitment and ultimate factors that interact with pathogens is important in addressing this global crisis.

Terrestrial pesticide exposure of amphibians: an underestimated cause of global decline?

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Brühl, Carsten A; Schmidt, Thomas; Pieper, Silvia; Alscher, Annika

2013-01-01

Amphibians, a class of animals in global decline, are present in agricultural landscapes characterized by agrochemical inputs. Effects of pesticides on terrestrial life stages of amphibians such as juvenile and adult frogs, toads and newts are little understood and a specific risk assessment for pesticide exposure, mandatory for other vertebrate groups, is currently not conducted. We studied the effects of seven pesticide products on juvenile European common frogs (Rana temporaria) in an agricultural overspray scenario. Mortality ranged from 100% after one hour to 40% after seven days at the recommended label rate of currently registered products. The demonstrated toxicity is alarming and a large-scale negative effect of terrestrial pesticide exposure on amphibian populations seems likely. Terrestrial pesticide exposure might be underestimated as a driver of their decline calling for more attention in conservation efforts and the risk assessment procedures in place do not protect this vanishing animal group.

Measuring the meltdown: drivers of global amphibian extinction and decline.

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Navjot S Sodhi

Full Text Available Habitat loss, climate change, over-exploitation, disease and other factors have been hypothesised in the global decline of amphibian biodiversity. However, the relative importance of and synergies among different drivers are still poorly understood. We present the largest global analysis of roughly 45% of known amphibians (2,583 species to quantify the influences of life history, climate, human density and habitat loss on declines and extinction risk. Multi-model Bayesian inference reveals that large amphibian species with small geographic range and pronounced seasonality in temperature and precipitation are most likely to be Red-Listed by IUCN. Elevated habitat loss and human densities are also correlated with high threat risk. Range size, habitat loss and more extreme seasonality in precipitation contributed to decline risk in the 2,454 species that declined between 1980 and 2004, compared to species that were stable (n = 1,545 or had increased (n = 28. These empirical results show that amphibian species with restricted ranges should be urgently targeted for conservation.

Measuring the meltdown: drivers of global amphibian extinction and decline.

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Sodhi, Navjot S; Bickford, David; Diesmos, Arvin C; Lee, Tien Ming; Koh, Lian Pin; Brook, Barry W; Sekercioglu, Cagan H; Bradshaw, Corey J A

2008-02-20

Habitat loss, climate change, over-exploitation, disease and other factors have been hypothesised in the global decline of amphibian biodiversity. However, the relative importance of and synergies among different drivers are still poorly understood. We present the largest global analysis of roughly 45% of known amphibians (2,583 species) to quantify the influences of life history, climate, human density and habitat loss on declines and extinction risk. Multi-model Bayesian inference reveals that large amphibian species with small geographic range and pronounced seasonality in temperature and precipitation are most likely to be Red-Listed by IUCN. Elevated habitat loss and human densities are also correlated with high threat risk. Range size, habitat loss and more extreme seasonality in precipitation contributed to decline risk in the 2,454 species that declined between 1980 and 2004, compared to species that were stable (n = 1,545) or had increased (n = 28). These empirical results show that amphibian species with restricted ranges should be urgently targeted for conservation.

Do pathogens become more virulent as they spread? Evidence from the amphibian declines in Central America.

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Phillips, Ben L; Puschendorf, Robert

2013-09-07

The virulence of a pathogen can vary strongly through time. While cyclical variation in virulence is regularly observed, directional shifts in virulence are less commonly observed and are typically associated with decreasing virulence of biological control agents through coevolution. It is increasingly appreciated, however, that spatial effects can lead to evolutionary trajectories that differ from standard expectations. One such possibility is that, as a pathogen spreads through a naive host population, its virulence increases on the invasion front. In Central America, there is compelling evidence for the recent spread of pathogenic Batrachochytrium dendrobatidis (Bd) and for its strong impact on amphibian populations. Here, we re-examine data on Bd prevalence and amphibian population decline across 13 sites from southern Mexico through Central America, and show that, in the initial phases of the Bd invasion, amphibian population decline lagged approximately 9 years behind the arrival of the pathogen, but that this lag diminished markedly over time. In total, our analysis suggests an increase in Bd virulence as it spread southwards, a pattern consistent with rapid evolution of increased virulence on Bd's invading front. The impact of Bd on amphibians might therefore be driven by rapid evolution in addition to more proximate environmental drivers.

Extinction debt as a driver of amphibian declines: An example with imperiled flatwoods salamanders

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Semiltsch, Raymond D; Walls, Susan; Barichivich, William J.; O'Donnell, Katherine

2017-01-01

A comprehensive view of population declines and their underlying causes is necessary to reverse species loss. Historically, in many cases, a narrow view may have allowed species declines to continue, virtually undetected, for long periods of time (perhaps even decades). We suggest that extinction debt is likely responsible for numerous (perhaps most) amphibian declines and that this perspective should be incorporated into the structure of amphibian research and management. Extinction debt, originally proposed to explain changes in species richness following environmental disturbance, also may refer to the proportion of populations of an individual species that is expected to eventually be lost because of habitat change. A conservation framework to address extinction debt focuses research on threats at the individual, population, and metapopulation levels. This approach will help enhance, restore, and protect specific processes and habitats at the proper scale by directing management to the most vulnerable level and stage of a species. We illustrate this approach using Flatwoods Salamanders, Ambystoma cingulatumand Ambystoma bishopi, which occurred historically throughout the Coastal Plain of the southeastern United States but have experienced a greater than 85% loss of populations in recent years. Reversal of these losses is possible only if conservation and recovery efforts encompass individual, population, and metapopulation levels. We illustrate our framework by outlining actions that could be taken at each of these levels to help guide conservation and management of amphibians with complex life cycles and provide options for how to prioritize conservation actions in the face of logistical and budgetary shortfalls.

Quantitative evidence for the effects of multiple drivers on continental-scale amphibian declines

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Grant, Evan H. Campbell; Miller, David A. W.; Schmidt, Benedikt R.; Adams, Michael J.; Amburgey, Staci M.; Chambert, Thierry A.; Cruickshank, Sam S.; Fisher, Robert N.; Green, David M.; Hossack, Blake R.; Johnson, Pieter T.J.; Joseph, Maxwell B.; Rittenhouse, Tracy A. G.; Ryan, Maureen E.; Waddle, J. Hardin; Walls, Susan C.; Bailey, Larissa L.; Fellers, Gary M.; Gorman, Thomas A.; Ray, Andrew M.; Pilliod, David S.; Price, Steven J.; Saenz, Daniel; Sadinski, Walt; Muths, Erin L.

2016-01-01

Since amphibian declines were first proposed as a global phenomenon over a quarter century ago, the conservation community has made little progress in halting or reversing these trends. The early search for a “smoking gun” was replaced with the expectation that declines are caused by multiple drivers. While field observations and experiments have identified factors leading to increased local extinction risk, evidence for effects of these drivers is lacking at large spatial scales. Here, we use observations of 389 time-series of 83 species and complexes from 61 study areas across North America to test the effects of 4 of the major hypothesized drivers of declines. While we find that local amphibian populations are being lost from metapopulations at an average rate of 3.79% per year, these declines are not related to any particular threat at the continental scale; likewise the effect of each stressor is variable at regional scales. This result - that exposure to threats varies spatially, and populations vary in their response - provides little generality in the development of conservation strategies. Greater emphasis on local solutions to this globally shared phenomenon is needed.

Impact of forestry practices at a landscape scale on the dynamics of amphibian populations.

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Harper, Elizabeth B; Patrick, David A; Gibbs, James P

2015-12-01

Forest loss is a primary cause of worldwide amphibian decline. Timber harvesting in the United States has caused dramatic changes in quality and extent of forest ecosystems, and intensive forest management still occurs. Although numerous studies have documented substantial reductions in amphibian densities related to timber harvest, subsequent extinctions are rare. To better understand the population dynamics that have allowed so many amphibian species to persist in the face of widespread forest disturbance, we developed spatially explicit metapopulation models for four forest-dependent amphibian species (Lithobates sylvaticus, Ambystoma opacum, A. talpoideum, and A. maculatum) that incorporated demographic and habitat selection data derived from experiments conducted as part of the Land Use Effects on Amphibian Populations Project (LEAP). We projected local and landscape-scale population persistence under 108 different forestry practice scenarios, varying treatment (partial cut, clear-cut with coarse woody debris [CWD] removed, and clearcut with CWD retained), cut patch size (1, 10, or 50 ha), total area cut (10, 20, or 30%), and initial amphibian population size (5, 50, or 500 adult females per local breeding population). Under these scenarios, landscape-scale extinction was highly unlikely, occurring in amphibian populations in the United States should focus not on questions of landscape-scale extinction but on the ecological consequences of dramatic reductions in amphibian biomass, including changes in trophic interactions, nutrient cycling, and energy transfer. Additionally, we conclude that amphibian declines and extinctions are far more likely to occur as a result of permanent habitat loss resulting from development than from the temporary degradation of habitat caused by current forestry practices.

First record of Saprolegnia sp. in an amphibian population in Colombia

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Luis Daniel Prada-Salcedo

2011-12-01

Full Text Available Most research related to the decline of amphibians has been focused on the detection of the pathogenic fungus Batrachochytriumdendrobatidis. This fungus is the main pathogen detected around the world. However, research has shown the presence of another fungus,Saprolegnia ferax, as a cause of mortality in amphibians in North America. Our study suggests a possible interspecific transmissioncaused by the presence of rainbow trout; thus, amphibian declines may not be attributable only to the presence of a single pathogen, butto other organisms and factors. Materials and methods. Our study revealed the presence of Saprolegnia sp. in the Andean frog Atelopusmittermeieri using the imprinting technique with lactophenol blue staining, which allowed the typical structures of this fungus to beobserved. Results. The importance of this discovery is the presence of two pathogenic fungi, B. dendrobatidis and Saprolegnia, whichaffecting simultaneously a population of amphibians. This finding brings attention to the eventual presence of other microorganismsthat might be involved individually or collectively in the decline of amphibian species. Conclusions. This record suggests a possibletransmission between rainbow trout (Oncorhynchus mykiss, an introduced species in the highlands of Colombia, which shares thesame habitats with different species of amphibians in the Sanctuary of Flora and Fauna Guanentá in the upper river Fonce in the midCordillera Oriental of Colombia.

The link between rapid enigmatic amphibian decline and the globally emerging chytrid fungus.

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Lötters, Stefan; Kielgast, Jos; Bielby, Jon; Schmidtlein, Sebastian; Bosch, Jaime; Veith, Michael; Walker, Susan F; Fisher, Matthew C; Rödder, Dennis

2009-09-01

Amphibians are globally declining and approximately one-third of all species are threatened with extinction. Some of the most severe declines have occurred suddenly and for unknown reasons in apparently pristine habitats. It has been hypothesized that these "rapid enigmatic declines" are the result of a panzootic of the disease chytridiomycosis caused by globally emerging amphibian chytrid fungus. In a Species Distribution Model, we identified the potential distribution of this pathogen. Areas and species from which rapid enigmatic decline are known significantly overlap with those of highest environmental suitability to the chytrid fungus. We confirm the plausibility of a link between rapid enigmatic decline in worldwide amphibian species and epizootic chytridiomycosis.

Cool temperatures reduce antifungal activity of symbiotic bacteria of threatened amphibians--implications for disease management and patterns of decline.

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Joshua H Daskin

Full Text Available Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd, is a widespread disease of amphibians responsible for population declines and extinctions. Some bacteria from amphibians' skins produce antimicrobial substances active against Bd. Supplementing populations of these cutaneous antifungal bacteria might help manage chytridiomycosis in wild amphibians. However, the activity of protective bacteria may depend upon environmental conditions. Biocontrol of Bd in nature thus requires knowledge of how environmental conditions affect their anti-Bd activity. For example, Bd-driven amphibian declines have often occurred at temperatures below Bd's optimum range. It is possible these declines occurred due to reduced anti-Bd activity of bacterial symbionts at cool temperatures. Better understanding of the effects of temperature on chytridiomycosis development could also improve risk evaluation for amphibian populations yet to encounter Bd. We characterized, at a range of temperatures approximating natural seasonal variation, the anti-Bd activity of bacterial symbionts from the skins of three species of rainforest tree frogs (Litoria nannotis, Litoria rheocola, and Litoria serrata. All three species declined during chytridiomycosis outbreaks in the late 1980s and early 1990s and have subsequently recovered to differing extents. We collected anti-Bd bacterial symbionts from frogs and cultured the bacteria at constant temperatures from 8 °C to 33 °C. Using a spectrophotometric assay, we monitored Bd growth in cell-free supernatants (CFSs from each temperature treatment. CFSs from 11 of 24 bacteria showed reduced anti-Bd activity in vitro when they were produced at cool temperatures similar to those encountered by the host species during population declines. Reduced anti-Bd activity of metabolites produced at low temperatures may, therefore, partially explain the association between Bd-driven declines and cool temperatures. We show that to

Cool temperatures reduce antifungal activity of symbiotic bacteria of threatened amphibians--implications for disease management and patterns of decline.

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Daskin, Joshua H; Bell, Sara C; Schwarzkopf, Lin; Alford, Ross A

2014-01-01

Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a widespread disease of amphibians responsible for population declines and extinctions. Some bacteria from amphibians' skins produce antimicrobial substances active against Bd. Supplementing populations of these cutaneous antifungal bacteria might help manage chytridiomycosis in wild amphibians. However, the activity of protective bacteria may depend upon environmental conditions. Biocontrol of Bd in nature thus requires knowledge of how environmental conditions affect their anti-Bd activity. For example, Bd-driven amphibian declines have often occurred at temperatures below Bd's optimum range. It is possible these declines occurred due to reduced anti-Bd activity of bacterial symbionts at cool temperatures. Better understanding of the effects of temperature on chytridiomycosis development could also improve risk evaluation for amphibian populations yet to encounter Bd. We characterized, at a range of temperatures approximating natural seasonal variation, the anti-Bd activity of bacterial symbionts from the skins of three species of rainforest tree frogs (Litoria nannotis, Litoria rheocola, and Litoria serrata). All three species declined during chytridiomycosis outbreaks in the late 1980s and early 1990s and have subsequently recovered to differing extents. We collected anti-Bd bacterial symbionts from frogs and cultured the bacteria at constant temperatures from 8 °C to 33 °C. Using a spectrophotometric assay, we monitored Bd growth in cell-free supernatants (CFSs) from each temperature treatment. CFSs from 11 of 24 bacteria showed reduced anti-Bd activity in vitro when they were produced at cool temperatures similar to those encountered by the host species during population declines. Reduced anti-Bd activity of metabolites produced at low temperatures may, therefore, partially explain the association between Bd-driven declines and cool temperatures. We show that to avoid

Hydroperiod and cattle use associated with lower recruitment in an r-selected amphibian with a declining population trend in the Klamath Mountains, California

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Esther M. Cole; Rosemary Hartman; Malcolm P. North

2016-01-01

Recent population declines in amphibians associated with mortality in early life stages highlight the need for a better understanding of the environmental factors related to successful survival to metamorphosis. In our study, we closely examine the relative importance of environmental factors to three stages of recruitment for Cascade frogs (Rana cascadae...

Agrochemicals increase trematode infections in a declining amphibian species.

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Rohr, Jason R; Schotthoefer, Anna M; Raffel, Thomas R; Carrick, Hunter J; Halstead, Neal; Hoverman, Jason T; Johnson, Catherine M; Johnson, Lucinda B; Lieske, Camilla; Piwoni, Marvin D; Schoff, Patrick K; Beasley, Val R

2008-10-30

Global amphibian declines have often been attributed to disease, but ignorance of the relative importance and mode of action of potential drivers of infection has made it difficult to develop effective remediation. In a field study, here we show that the widely used herbicide, atrazine, was the best predictor (out of more than 240 plausible candidates) of the abundance of larval trematodes (parasitic flatworms) in the declining northern leopard frog Rana pipiens. The effects of atrazine were consistent across trematode taxa. The combination of atrazine and phosphate--principal agrochemicals in global corn and sorghum production--accounted for 74% of the variation in the abundance of these often debilitating larval trematodes (atrazine alone accounted for 51%). Analysis of field data supported a causal mechanism whereby both agrochemicals increase exposure and susceptibility to larval trematodes by augmenting snail intermediate hosts and suppressing amphibian immunity. A mesocosm experiment demonstrated that, relative to control tanks, atrazine tanks had immunosuppressed tadpoles, had significantly more attached algae and snails, and had tadpoles with elevated trematode loads, further supporting a causal relationship between atrazine and elevated trematode infections in amphibians. These results raise concerns about the role of atrazine and phosphate in amphibian declines, and illustrate the value of quantifying the relative importance of several possible drivers of disease risk while determining the mechanisms by which they facilitate disease emergence.

Rapid increases and time-lagged declines in amphibian occupancy after wildfire.

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Hossack, Blake R; Lowe, Winsor H; Corn, Paul Stephen

2013-02-01

Climate change is expected to increase the frequency and severity of drought and wildfire. Aquatic and moisture-sensitive species, such as amphibians, may be particularly vulnerable to these modified disturbance regimes because large wildfires often occur during extended droughts and thus may compound environmental threats. However, understanding of the effects of wildfires on amphibians in forests with long fire-return intervals is limited. Numerous stand-replacing wildfires have occurred since 1988 in Glacier National Park (Montana, U.S.A.), where we have conducted long-term monitoring of amphibians. We measured responses of 3 amphibian species to fires of different sizes, severity, and age in a small geographic area with uniform management. We used data from wetlands associated with 6 wildfires that burned between 1988 and 2003 to evaluate whether burn extent and severity and interactions between wildfire and wetland isolation affected the distribution of breeding populations. We measured responses with models that accounted for imperfect detection to estimate occupancy during prefire (0-4 years) and different postfire recovery periods. For the long-toed salamander (Ambystoma macrodactylum) and Columbia spotted frog (Rana luteiventris), occupancy was not affected for 6 years after wildfire. But 7-21 years after wildfire, occupancy for both species decreased ≥ 25% in areas where >50% of the forest within 500 m of wetlands burned. In contrast, occupancy of the boreal toad (Anaxyrus boreas) tripled in the 3 years after low-elevation forests burned. This increase in occupancy was followed by a gradual decline. Our results show that accounting for magnitude of change and time lags is critical to understanding population dynamics of amphibians after large disturbances. Our results also inform understanding of the potential threat of increases in wildfire frequency or severity to amphibians in the region. ©2012 Society for Conservation Biology.

Amphibian Declines Are Not Uniquely High amongst the Vertebrates: Trend Determination and the British Perspective

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John Buckley

2009-09-01

Full Text Available Although amphibians have experienced major global declines and an increasing extinction rate, recent results indicate that they are not as uniquely disadvantaged as previously supposed. Acquisition of robust data is evidently crucial to the determination of both absolute and relative rates of biodiversity declines, and thus in prioritising conservation actions. In Britain there is arguably a longer history of recording, and attempting to conserve, a wide range of species groups than anywhere else in the world. This stems from the early activities of Victorian naturalists in the nineteenth century, the establishment of natural history societies and, since the mid-twentieth century, a range of national recording schemes and organisations actively involved in conservation. In this review we summarise comparative evidence for British amphibians and reptiles concerning historical abundance, population trends and their causes, and outline how they relate to the situation elsewhere in Europe (and possibly the World. We discuss possible reasons why the plight of ectothermic vertebrates (fish, amphibians and reptiles seems generally worse than that of endotherms (birds and mammals, as well as research priorities and factors likely to impact amphibians and reptile conservation in future.

Evaluating the links between climate, disease spread, and amphibian declines.

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Rohr, Jason R; Raffel, Thomas R; Romansic, John M; McCallum, Hamish; Hudson, Peter J

2008-11-11

Human alteration of the environment has arguably propelled the Earth into its sixth mass extinction event and amphibians, the most threatened of all vertebrate taxa, are at the forefront. Many of the worldwide amphibian declines have been caused by the chytrid fungus, Batrachochytrium dendrobatidis (Bd), and two contrasting hypotheses have been proposed to explain these declines. Positive correlations between global warming and Bd-related declines sparked the chytrid-thermal-optimum hypothesis, which proposes that global warming increased cloud cover in warm years that drove the convergence of daytime and nighttime temperatures toward the thermal optimum for Bd growth. In contrast, the spatiotemporal-spread hypothesis states that Bd-related declines are caused by the introduction and spread of Bd, independent of climate change. We provide a rigorous test of these hypotheses by evaluating (i) whether cloud cover, temperature convergence, and predicted temperature-dependent Bd growth are significant positive predictors of amphibian extinctions in the genus Atelopus and (ii) whether spatial structure in the timing of these extinctions can be detected without making assumptions about the location, timing, or number of Bd emergences. We show that there is spatial structure to the timing of Atelopus spp. extinctions but that the cause of this structure remains equivocal, emphasizing the need for further molecular characterization of Bd. We also show that the reported positive multi-decade correlation between Atelopus spp. extinctions and mean tropical air temperature in the previous year is indeed robust, but the evidence that it is causal is weak because numerous other variables, including regional banana and beer production, were better predictors of these extinctions. Finally, almost all of our findings were opposite to the predictions of the chytrid-thermal-optimum hypothesis. Although climate change is likely to play an important role in worldwide amphibian declines

A strategy for monitoring and managing declines in an amphibian community.

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Grant, Evan H Campbell; Zipkin, Elise F; Nichols, James D; Campbell, J Patrick

2013-12-01

Although many taxa have declined globally, conservation actions are inherently local. Ecosystems degrade even in protected areas, and maintaining natural systems in a desired condition may require active management. Implementing management decisions under uncertainty requires a logical and transparent process to identify objectives, develop management actions, formulate system models to link actions with objectives, monitor to reduce uncertainty and identify system state (i.e., resource condition), and determine an optimal management strategy. We applied one such structured decision-making approach that incorporates these critical elements to inform management of amphibian populations in a protected area managed by the U.S. National Park Service. Climate change is expected to affect amphibian occupancy of wetlands and to increase uncertainty in management decision making. We used the tools of structured decision making to identify short-term management solutions that incorporate our current understanding of the effect of climate change on amphibians, emphasizing how management can be undertaken even with incomplete information. Estrategia para Monitorear y Manejar Disminuciones en una Comunidad de Anfibios. © 2013 Society for Conservation Biology.

Pesticides and Population Declines of California Alpine Frogs

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Airborne pesticides from the Central Valley of California have been implicated as a cause for population declines of several amphibian species, with the strongest evidence for the mountain yellow-legged frog complex (Rana muscosa and R. sierrae) in the Sierra Nevada. We measured ...

Amphibian population genetics in agricultural landscapes: does viniculture drive the population structuring of the European common frog (Rana temporaria?

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Patrick P. Lenhardt

2017-07-01

Full Text Available Amphibian populations have been declining globally over the past decades. The intensification of agriculture, habitat loss, fragmentation of populations and toxic substances in the environment are considered as driving factors for this decline. Today, about 50% of the area of Germany is used for agriculture and is inhabited by a diverse variety of 20 amphibian species. Of these, 19 are exhibiting declining populations. Due to the protection status of native amphibian species, it is important to evaluate the effect of land use and associated stressors (such as road mortality and pesticide toxicity on the genetic population structure of amphibians in agricultural landscapes. We investigated the effects of viniculture on the genetic differentiation of European common frog (Rana temporaria populations in Southern Palatinate (Germany. We analyzed microsatellite data of ten loci from ten breeding pond populations located within viniculture landscape and in the adjacent forest block and compared these results with a previously developed landscape permeability model. We tested for significant correlation of genetic population differentiation and landscape elements, including land use as well as roads and their associated traffic intensity, to explain the genetic structure in the study area. Genetic differentiation among forest populations was significantly lower (median pairwise FST = 0.0041 at 5.39 km to 0.0159 at 9.40 km distance than between viniculture populations (median pairwise FST = 0.0215 at 2.34 km to 0.0987 at 2.39 km distance. Our analyses rejected isolation by distance based on roads and associated traffic intensity as the sole explanation of the genetic differentiation and suggest that the viniculture landscape has to be considered as a limiting barrier for R. temporaria migration, partially confirming the isolation of breeding ponds predicted by the landscape permeability model. Therefore, arable land may act as a sink habitat

The state of amphibians in the United States

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Muths, E.; Adams, M.J.; Grant, E.H.C.; Miller, D.; Corn, P.S.; Ball, L.C.

2012-01-01

More than 25 years ago, scientists began to identify unexplained declines in amphibian populations around the world. Much has been learned since then, but amphibian declines have not abated and the interactions among the various threats to amphibians are not clear. Amphibian decline is a problem of local, national, and international scope that can affect ecosystem function, biodiversity, and commerce. This fact sheet provides a snapshot of the state of the amphibians and introduces examples to illustrate the range of issues in the United States.

Emerging Ranaviral Infectious Diseases and Amphibian Decline

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Jacques Robert

2010-02-01

Full Text Available Infectious diseases caused by ranaviruses (RV, family Iridoviridae not only affect wild amphibian populations but also agriculture and international animal trade. Although, the prevalence of RV infections and die offs has markedly increased over the last decade, it is still unclear whether these viruses are direct causal agents of extinction or rather are the resulting (secondary consequences of weakened health of amphibian populations leading to increased susceptibility to viral pathogens. In either case, it is important to understand the critical role of host immune defense in controlling RV infections, pathogenicity, and transmission; this is the focus of this review.

Linking global climate and temperature variability to widespread amphibian declines putatively caused by disease.

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Rohr, Jason R; Raffel, Thomas R

2010-05-04

The role of global climate change in the decline of biodiversity and the emergence of infectious diseases remains controversial, and the effect of climatic variability, in particular, has largely been ignored. For instance, it was recently revealed that the proposed link between climate change and widespread amphibian declines, putatively caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), was tenuous because it was based on a temporally confounded correlation. Here we provide temporally unconfounded evidence that global El Niño climatic events drive widespread amphibian losses in genus Atelopus via increased regional temperature variability, which can reduce amphibian defenses against pathogens. Of 26 climate variables tested, only factors associated with temperature variability could account for the spatiotemporal patterns of declines thought to be associated with Bd. Climatic predictors of declines became significant only after controlling for a pattern consistent with epidemic spread (by temporally detrending the data). This presumed spread accounted for 59% of the temporal variation in amphibian losses, whereas El Niño accounted for 59% of the remaining variation. Hence, we could account for 83% of the variation in declines with these two variables alone. Given that global climate change seems to increase temperature variability, extreme climatic events, and the strength of Central Pacific El Niño episodes, climate change might exacerbate worldwide enigmatic declines of amphibians, presumably by increasing susceptibility to disease. These results suggest that changes to temperature variability associated with climate change might be as significant to biodiversity losses and disease emergence as changes to mean temperature.

The potential influence of environmental pollution on amphibian development and decline

Energy Technology Data Exchange (ETDEWEB)

Jung, R.E.

1996-12-31

Globally, amphibians are reportedly declining. Environmental pollution has been hypothesized to be associated with declines. Because of their aquatic development and permeable eggs, skin and gills, amphibians, like fishes, may be particularly susceptible to poor water quality or waterborne pollutants. This dissertation addresses effects of global pollutants such as pesticides, acid rain and associated metal toxicity, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and polychlorinated biphenyls (PCBs) on the development, behavior, and physiology of amphibian early life stages. This report contains only chapter six and conclusions. Chapter 6 reports on a field experiment in which green frogs from two clutches were exposed from egg to 107 days of age to water and sediments in enclosures along a PCB and metal contamination gradient in the Fox River and wetlands near Green Bay, Wisconsin. Green frogs showed lower hatching success and survival at sites with higher contaminant levels compared to cleaner wetland sites along Green Bay. Hatching success in the green frog was most significantly negatively correlated with sediment PCB levels. It can be concluded that environmental pollution and toxicants in aquatic environments can cause problems for amphibian early development. Sometimes the effects are subtle, and sometimes they are dramatic. In general, amphibian early life stages seem particularly sensitive to environmentally-realistic levels of low pH and metals, but appear more tolerant of TCDD and PCBs.

Relationship Between Landscape Character, UV Exposure, and Amphibian Decline

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O'Reilly, C. M.; Brooks, P. D.; Corn, P. S.; Muths, E.; Campbell, D. H.; Diamond, S.; Tonnessen, K.

2001-12-01

Widespread reports of amphibian declines have been considered a warning of large-scale environmental degradation, yet the reasons for these declines remain unclear. This study suggests that exposure to ultraviolet radiation may act as an environmental stressor that affects population breeding success or susceptibility to disease. Ultraviolet radiation is attenuated by dissolved and particulate compounds in water, which may be of either terrestrial or aquatic origin. UV attenuation by dissolved organic carbon (DOC) is primarily due to compounds in the fulvic acid fraction, which originate in soil environments. These terrestrially-derived fulvic acids are transported to during hydrologic flushing events such as snowmelt and episodic precipitation and play an important role in controlling UV exposure in surface waters. As part of a previously published project, amphibian surveys were conducted at seventeen sites in Rocky Mountain National Park both during, and subsequent to, a three-year drought (1988 - 1990). During this period, ten sites lost one amphibian species, while only one site gained a previously unreported species. One possible explanation for these localized species losses is increased exposure to UV radiation, mediated by reduced terrestrial DOC inputs during dry periods. Several subsequent years of water chemistry data showed that the sites with documented species losses were characterized by a range of DOC concentrations, but tended to have a greater proportion of terrestrial DOC than sites that did not undergo species loss. This suggests that terrestrial inputs exert a strong control on DOC concentrations that may influence species success. We used physical environmental factors to develop a classification scheme for these sites. There are many physical factors that can influence terrestrial DOC inputs, including landscape position, geomorphology, soil type, and watershed vegetation. In addition, we considered the possible effects on internal aquatic

A statistical assessment of population trends for data deficient Mexican amphibians

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Esther Quintero

2014-12-01

Full Text Available Background. Mexico has the world’s fifth largest population of amphibians and the second country with the highest quantity of threatened amphibian species. About 10% of Mexican amphibians lack enough data to be assigned to a risk category by the IUCN, so in this paper we want to test a statistical tool that, in the absence of specific demographic data, can assess a species’ risk of extinction, population trend, and to better understand which variables increase their vulnerability. Recent studies have demonstrated that the risk of species decline depends on extrinsic and intrinsic traits, thus including both of them for assessing extinction might render more accurate assessment of threats.Methods. We harvested data from the Encyclopedia of Life (EOL and the published literature for Mexican amphibians, and used these data to assess the population trend of some of the Mexican species that have been assigned to the Data Deficient category of the IUCN using Random Forests, a Machine Learning method that gives a prediction of complex processes and identifies the most important variables that account for the predictions.Results. Our results show that most of the data deficient Mexican amphibians that we used have decreasing population trends. We found that Random Forests is a solid way to identify species with decreasing population trends when no demographic data is available. Moreover, we point to the most important variables that make species more vulnerable for extinction. This exercise is a very valuable first step in assigning conservation priorities for poorly known species.

A statistical assessment of population trends for data deficient Mexican amphibians.

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Quintero, Esther; Thessen, Anne E; Arias-Caballero, Paulina; Ayala-Orozco, Bárbara

2014-01-01

Background. Mexico has the world's fifth largest population of amphibians and the second country with the highest quantity of threatened amphibian species. About 10% of Mexican amphibians lack enough data to be assigned to a risk category by the IUCN, so in this paper we want to test a statistical tool that, in the absence of specific demographic data, can assess a species' risk of extinction, population trend, and to better understand which variables increase their vulnerability. Recent studies have demonstrated that the risk of species decline depends on extrinsic and intrinsic traits, thus including both of them for assessing extinction might render more accurate assessment of threats. Methods. We harvested data from the Encyclopedia of Life (EOL) and the published literature for Mexican amphibians, and used these data to assess the population trend of some of the Mexican species that have been assigned to the Data Deficient category of the IUCN using Random Forests, a Machine Learning method that gives a prediction of complex processes and identifies the most important variables that account for the predictions. Results. Our results show that most of the data deficient Mexican amphibians that we used have decreasing population trends. We found that Random Forests is a solid way to identify species with decreasing population trends when no demographic data is available. Moreover, we point to the most important variables that make species more vulnerable for extinction. This exercise is a very valuable first step in assigning conservation priorities for poorly known species.

Evidence of disease-related amphibian decline in Colorado

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Muths, Erin; Corn, Paul Stephen; Pessier, Allan P.; Green, D. Earl

2003-01-01

The recent discovery of a pathogenic fungus (Batrachochytrium dendrobatidis) associated with declines of frogs in the American and Australian tropics, suggests that at least the proximate cause, may be known for many previously unexplained amphibian declines. We have monitored boreal toads in Colorado since 1991 at four sites using capturea??recapture of adults and counts of egg masses to examine the dynamics of this metapopulation. Numbers of male toads declined in 1996 and 1999 with annual survival rate averaging 78% from 1991 to 1994, 45% in 1995 and 3% between 1998 and 1999. Numbers of egg masses also declined. An etiological diagnosis of chytridiomycosis consistent with infections by the genus Batrachochytrium was made in six wild adult toads. Characteristic histomorphological features (i.e. intracellular location, shape of thalli, presence of discharge tubes and rhizoids) of chytrid organisms, and host tissue response (acanthosis and hyperkeratosis) were observed in individual toads. These characteristics were indistinguishable from previously reported mortality events associated with chytrid fungus. We also observed epizootiological features consistent with mortality events associated with chytrid fungus: an increase in the ratio of female:male toads captured, an apparent spread of mortalities within the metapopulation and mortalities restricted to post metamorphic animals. Eleven years of population data suggest that this metapopulation of toads is in danger of extinction, pathological and epizootiological evidence indicates that B. dendrobatidis has played a proximate role in this process

Pesticide Mixtures, Endocrine Disruption, and Amphibian Declines: Are We Underestimating the Impact?

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Hayes, Tyrone B.; Case, Paola; Chui, Sarah; Chung, Duc; Haeffele, Cathryn; Haston, Kelly; Lee, Melissa; Mai, Vien Phoung; Marjuoa, Youssra; Parker, John; Tsui, Mable

2006-01-01

Amphibian populations are declining globally at an alarming rate. Pesticides are among a number of proposed causes for these declines. Although a sizable database examining effects of pesticides on amphibians exists, the vast majority of these studies focus on toxicological effects (lethality, external malformations, etc.) at relatively high doses (parts per million). Very few studies focus on effects such as endocrine disruption at low concentrations. Further, most studies examine exposures to single chemicals only. The present study examined nine pesticides (four herbicides, two fungicides, and three insecticides) used on cornfields in the midwestern United States. Effects of each pesticide alone (0.1 ppb) or in combination were examined. In addition, we also examined atrazine and S-metolachlor combined (0.1 or 10 ppb each) and the commercial formulation Bicep II Magnum, which contains both of these herbicides. These two pesticides were examined in combination because they are persistent throughout the year in the wild. We examined larval growth and development, sex differentiation, and immune function in leopard frogs (Rana pipiens). In a follow-up study, we also examined the effects of the nine-compound mixture on plasma corticosterone levels in male African clawed frogs (Xenopus laevis). Although some of the pesticides individually inhibited larval growth and development, the pesticide mixtures had much greater effects. Larval growth and development were retarded, but most significantly, pesticide mixtures negated or reversed the typically positive correlation between time to metamorphosis and size at metamorphosis observed in controls: exposed larvae that took longer to metamorphose were smaller than their counterparts that metamorphosed earlier. The nine-pesticide mixture also induced damage to the thymus, resulting in immunosuppression and contraction of flavobacterial meningitis. The study in X. laevis revealed that these adverse effects may be due to an

Overview of chytrid emergence and impacts on amphibians

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2016-01-01

Chytridiomycosis is an emerging infectious disease of amphibians that affects over 700 species on all continents where amphibians occur. The amphibian–chytridiomycosis system is complex, and the response of any amphibian species to chytrid depends on many aspects of the ecology and evolutionary history of the amphibian, the genotype and phenotype of the fungus, and how the biological and physical environment can mediate that interaction. Impacts of chytridiomycosis on amphibians are varied; some species have been driven extinct, populations of others have declined severely, whereas still others have not obviously declined. Understanding patterns and mechanisms of amphibian responses to chytrids is critical for conservation and management. Robust estimates of population numbers are needed to identify species at risk, prioritize taxa for conservation actions, design management strategies for managing populations and species, and to develop effective measures to reduce impacts of chytrids on amphibians. This article is part of the themed issue ‘Tackling emerging fungal threats to animal health, food security and ecosystem resilience’. PMID:28080989

Differences in sensitivity to the fungal pathogen Batrachochytrium dendrobatidis among amphibian populations

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Paul W. Bradley; Stephanie S. Gervasi; Jessica Hua; Rickey D. Cothran; Rick A. Relyea; Deanna H. Olson; Andrew R. Blaustein

2015-01-01

Contributing to the worldwide biodiversity crisis are emerging infectious diseases, which can lead to extirpations and extinctions of hosts. For example, the infectious fungal pathogen Batrachochytrium dendrobatidis (Bd) is associated with worldwide amphibian population declines and extinctions. Sensitivity to Bd varies with species, season, and life stage. However,...

Evaluating Ultraviolet Radiation Exposures Determined from TOMS Satellite Data at Sites of Amphibian Declines in Central and South America

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Middleton, Elizabeth M.; Smith, David E. (Technical Monitor)

2000-01-01

Many amphibian species have experienced substantial population declines, or have disappeared altogether, during the last several decades at a number of amphibian census sites in Central and South America. This study addresses the use of satellite-derived trends in solar ultraviolet-B (UV-B; 280-320 nm) radiation exposures at these sites over the last two decades, and is intended to demonstrate a role for satellite observations in determining whether UV-B radiation is a contributing factor in amphibian declines. UV-B radiation levels at the Earth's surface were derived from the Total Ozone Mapping Spectrometer (TOMS) satellite data, typically acquired daily since 1979. These data were used to calculate the daily erythemal (sunburning) UV-B, or UV-B(sub ery), exposures at the latitude, longitude, and elevation of each of 20 census sites. The annually averaged UV-B(sub ery) dose, as well as the maximum values, have been increasing in both Central and South America, with higher levels received at the Central American sites. The annually averaged UV-B(sub ery) exposures increased significantly from 1979-1998 at all 11 Central American sites examined (r(exp 2) = 0.60 - 0.79; P= 6750 J/sq m*d) to the annual UV-B(sub ery) total has increased from approx. 5% to approx. 15% in Central America over the 19 year period, but actual daily exposures for each species are unknown. Synergy among UV-B radiation and other factors, especially those associated with alterations of water chemistry (e.g., acidification) in aqueous habitats is discussed. These findings justify further research concerning whether UV-B(sub ery) radiation plays a role in amphibian population declines and extinctions.

Perspectives from the Aldo Leopold Wilderness Research Institute: Amphibians and wilderness

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Corn, Paul Stephen

2001-01-01

The decline of amphibian species has emerged as a major global conservation issue in the last decade. Last year, the Department of the Interior (DOI) initiated a major national initiative to detect trends in amphibian populations and research the causes of declines. The program, conducted principally by the U.S. Geological Survey (USGS), emphasizes lands managed by DOI, but collaboration with the Forest Service is encouraged to increase the scope of inference about population trends. Although amphibians are not usually the first group of animals that comes to mind when one thinks of wilderness, conservation of amphibian populations is clearly a wilderness issue.

Assessing the links among environmental contaminants, endocrinology, and parasites to understand amphibian declines in montane regions of Costa Rica.

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Leary, Christopher J; Ralicki, Hannah F; Laurencio, David; Crocker-Buta, Sarah; Malone, John H

2018-01-01

Amphibians inhabiting montane riparian zones in the Neotropics are particularly vulnerable to decline, but the reasons are poorly understood. Because environmental contaminants, endocrine disruption, and pathogens often figure prominently in amphibian declines it is imperative that we understand how these factors are potentially interrelated to affect montane populations. One possibility is that increased precipitation associated with global warming promotes the deposition of contaminants in montane regions. Increased exposure to contaminants, in turn, potentially elicits chronic elevations in circulating stress hormones that could contribute to montane population declines by compromising resistance to pathogens and/or production of sex steroids regulating reproduction. Here, we test this hypothesis by examining contaminant levels, stress and sex steroid levels, and nematode abundances in male drab treefrogs, Smilisca sordida, from lowland and montane populations in Costa Rica. We found no evidence that montane populations were more likely to possess contaminants (i.e., organochlorine, organophosphate and carbamate pesticides or benzidine and chlorophenoxy herbicides) than lowland populations. We also found no evidence of elevational differences in circulating levels of the stress hormone corticosterone, estradiol or progesterone. However, montane populations possessed lower androgen levels, hosted more nematode species, and had higher nematode abundances than lowland populations. Although these results suggested that nematodes contributed to lower androgens in montane populations, we were unable to detect a significant inverse relationship between nematode abundance and androgen level. Our results suggest that montane populations of this species are not at greater risk of exposure to contaminants or chronic stress, but implicate nematodes and compromised sex steroid levels as potential threats to montane populations.

Assessing the links among environmental contaminants, endocrinology, and parasites to understand amphibian declines in montane regions of Costa Rica.

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Christopher J Leary

Full Text Available Amphibians inhabiting montane riparian zones in the Neotropics are particularly vulnerable to decline, but the reasons are poorly understood. Because environmental contaminants, endocrine disruption, and pathogens often figure prominently in amphibian declines it is imperative that we understand how these factors are potentially interrelated to affect montane populations. One possibility is that increased precipitation associated with global warming promotes the deposition of contaminants in montane regions. Increased exposure to contaminants, in turn, potentially elicits chronic elevations in circulating stress hormones that could contribute to montane population declines by compromising resistance to pathogens and/or production of sex steroids regulating reproduction. Here, we test this hypothesis by examining contaminant levels, stress and sex steroid levels, and nematode abundances in male drab treefrogs, Smilisca sordida, from lowland and montane populations in Costa Rica. We found no evidence that montane populations were more likely to possess contaminants (i.e., organochlorine, organophosphate and carbamate pesticides or benzidine and chlorophenoxy herbicides than lowland populations. We also found no evidence of elevational differences in circulating levels of the stress hormone corticosterone, estradiol or progesterone. However, montane populations possessed lower androgen levels, hosted more nematode species, and had higher nematode abundances than lowland populations. Although these results suggested that nematodes contributed to lower androgens in montane populations, we were unable to detect a significant inverse relationship between nematode abundance and androgen level. Our results suggest that montane populations of this species are not at greater risk of exposure to contaminants or chronic stress, but implicate nematodes and compromised sex steroid levels as potential threats to montane populations.

Amphibian decline: an integrated analysis of multiple stressor effects

Energy Technology Data Exchange (ETDEWEB)

Linder, G.; Krest, S.K.; Sparkling, D.W. (eds.)

2003-07-01

Environmental effects of stressors on amphibians have received increased attention but little is known about the effects of these stressors on amphibian populations. The workshop addressed this issue. The proceedings contain 15 chapters, two of which mention effects of coal combustion wastes. These are: Chapter 4: Chemical stressors, by J.H. Burkhart, J.R. Bidwell, D.J. Fort, S.R. Sheffield, and Chapter 8E: Anthropogenic activities producing sink habitats for amphibians in the local landscape: a case study of lethal and sublethal effects of coal combustion residues in the aquatic environment by C.L. Rose and W.A. Hopkins.

Trends in amphibian occupancy in the United States

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Adams, Michael J.; Miller, David A.W.; Muths, Erin; Corn, Paul Stephen; Grant, Evan H. Campbell; Bailey, Larissa L.; Fellers, Gary M.; Fisher, Robert N.; Sadinski, Walter J.; Waddle, Hardin; Walls, Susan C.

2013-01-01

Though a third of amphibian species worldwide are thought to be imperiled, existing assessments simply categorize extinction risk, providing little information on the rate of population losses. We conducted the first analysis of the rate of change in the probability that amphibians occupy ponds and other comparable habitat features across the United States. We found that overall occupancy by amphibians declined 3.7% annually from 2002 to 2011. Species that are Red-listed by the International Union for Conservation of Nature (IUCN) declined an average of 11.6% annually. All subsets of data examined had a declining trend including species in the IUCN Least Concern category. This analysis suggests that amphibian declines may be more widespread and severe than previously realized.

Trends in amphibian occupancy in the United States.

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Michael J Adams

Full Text Available Though a third of amphibian species worldwide are thought to be imperiled, existing assessments simply categorize extinction risk, providing little information on the rate of population losses. We conducted the first analysis of the rate of change in the probability that amphibians occupy ponds and other comparable habitat features across the United States. We found that overall occupancy by amphibians declined 3.7% annually from 2002 to 2011. Species that are Red-listed by the International Union for Conservation of Nature (IUCN declined an average of 11.6% annually. All subsets of data examined had a declining trend including species in the IUCN Least Concern category. This analysis suggests that amphibian declines may be more widespread and severe than previously realized.

Estimating Herd Immunity to Amphibian Chytridiomycosis in Madagascar Based on the Defensive Function of Amphibian Skin Bacteria

OpenAIRE

Bletz, Molly C.; Myers, Jillian; Woodhams, Douglas C.; Rabemananjara, Falitiana C. E.; Rakotonirina, Angela; Weldon, Che; Edmonds, Devin; Vences, Miguel; Harris, Reid N.

2017-01-01

For decades, Amphibians have been globally threatened by the still expanding infectious disease, chytridiomycosis. Madagascar is an amphibian biodiversity hotspot where Batrachochytrium dendrobatidis (Bd) has only recently been detected. While no Bd-associated population declines have been reported, the risk of declines is high when invasive virulent lineages become involved. Cutaneous bacteria contribute to host innate immunity by providing defense against pathogens for numerous animals, inc...

Evaluating Amphibian Declines with Site Revisits and Occupancy Models: Status of Montane Anurans in the Pacific Northwest USA

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Brome McCreary

2009-12-01

Full Text Available Amphibian declines have been reported in mountainous areas around the western USA. Few data quantify the extent of population losses in the Pacific Northwest, a region in which amphibian declines have received much attention. From 2001–2004, we resurveyed historical breeding sites of two species of conservation concern, the Western Toad (Bufo [=Anaxyrus] boreas and Cascades Frog (Rana cascadae. We detected B. boreas breeding at 75.9% and R. cascadae breeding at 66.6% of historical sites. When we analyzed the data using occupancy models that accounted for detection probability, we estimated the current use of historically occupied sites in our study area was 84.9% (SE = 4.9 for B. boreas and 72.4% (SE = 6.6 for R. cascadae. Our ability to detect B. boreas at sites where they were present was lower in the first year of surveys (a low snowpack year and higher at sites with introduced fish. Our ability to detect R. cascadae was lower at sites with fish. The probability that B. boreas still uses a historical site for breeding was related to the easting of the site (+ and the age of record (-. None of the variables we analyzed was strongly related to R. cascadae occupancy. Both species had increased odds of occupancy with higher latitude, but model support for this variable was modest. Our analysis suggests that while local losses are possible, these two amphibians have not experienced recent, broad population losses in the Oregon Cascades. Historical site revisitation studies such as ours cannot distinguish between population losses and site switching, and do not account for colonization of new habitats, so our analysis may overestimate declines in occupancy within our study area.

Climatic change and wetland desiccation cause amphibian decline in Yellowstone National Park.

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McMenamin, Sarah K; Hadly, Elizabeth A; Wright, Christopher K

2008-11-04

Amphibians are a bellwether for environmental degradation, even in natural ecosystems such as Yellowstone National Park in the western United States, where species have been actively protected longer than anywhere else on Earth. We document that recent climatic warming and resultant wetland desiccation are causing severe declines in 4 once-common amphibian species native to Yellowstone. Climate monitoring over 6 decades, remote sensing, and repeated surveys of 49 ponds indicate that decreasing annual precipitation and increasing temperatures during the warmest months of the year have significantly altered the landscape and the local biological communities. Drought is now more common and more severe than at any time in the past century. Compared with 16 years ago, the number of permanently dry ponds in northern Yellowstone has increased 4-fold. Of the ponds that remain, the proportion supporting amphibians has declined significantly, as has the number of species found in each location. Our results indicate that climatic warming already has disrupted one of the best-protected ecosystems on our planet and that current assessments of species' vulnerability do not adequately consider such impacts.

Population recovery following decline in an endangered stream-breeding frog (Mixophyes fleayi from subtropical Australia.

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David Alan Newell

Full Text Available Amphibians have undergone dramatic declines and extinctions worldwide. Prominent among these have been the stream-breeding frogs in the rainforests of eastern Australia. The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd has been postulated as the primary cause of these declines. We conducted a capture-mark-recapture study over a 7-year period on the endangered Fleay's barred frog (Mixophyes fleayi at two independent streams (30 km apart in order to assess the stability of these populations. This species had undergone a severe decline across its narrow geographic range. Mark-recapture modelling showed that the number of individuals increased 3-10 fold along stream transects over this period. Frog detection probabilities were frequently above 50% but declined as the populations increased. Adult survival was important to overall population persistence in light of low recruitment events, suggesting that longevity may be a key factor in this recovery. One male and female were present in the capture record for >6 years. This study provides an unambiguous example of population recovery in the presence of Bd.

Correlates of virulence in a frog-killing fungal pathogen: evidence from a California amphibian decline.

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Piovia-Scott, Jonah; Pope, Karen; Worth, S Joy; Rosenblum, Erica Bree; Poorten, Thomas; Refsnider, Jeanine; Rollins-Smith, Louise A; Reinert, Laura K; Wells, Heather L; Rejmanek, Dan; Lawler, Sharon; Foley, Janet

2015-07-01

The fungal pathogen Batrachochytrium dendrobatidis (Bd) has caused declines and extinctions in amphibians worldwide, and there is increasing evidence that some strains of this pathogen are more virulent than others. While a number of putative virulence factors have been identified, few studies link these factors to specific epizootic events. We documented a dramatic decline in juvenile frogs in a Bd-infected population of Cascades frogs (Rana cascadae) in the mountains of northern California and used a laboratory experiment to show that Bd isolated in the midst of this decline induced higher mortality than Bd isolated from a more stable population of the same species of frog. This highly virulent Bd isolate was more toxic to immune cells and attained higher density in liquid culture than comparable isolates. Genomic analyses revealed that this isolate is nested within the global panzootic lineage and exhibited unusual genomic patterns, including increased copy numbers of many chromosomal segments. This study integrates data from multiple sources to suggest specific phenotypic and genomic characteristics of the pathogen that may be linked to disease-related declines.

Batrachochytrium salamandrivorans sp. nov. causes lethal chytridiomycosis in amphibians.

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Martel, An; Spitzen-van der Sluijs, Annemarieke; Blooi, Mark; Bert, Wim; Ducatelle, Richard; Fisher, Matthew C; Woeltjes, Antonius; Bosman, Wilbert; Chiers, Koen; Bossuyt, Franky; Pasmans, Frank

2013-09-17

The current biodiversity crisis encompasses a sixth mass extinction event affecting the entire class of amphibians. The infectious disease chytridiomycosis is considered one of the major drivers of global amphibian population decline and extinction and is thought to be caused by a single species of aquatic fungus, Batrachochytrium dendrobatidis. However, several amphibian population declines remain unexplained, among them a steep decrease in fire salamander populations (Salamandra salamandra) that has brought this species to the edge of local extinction. Here we isolated and characterized a unique chytrid fungus, Batrachochytrium salamandrivorans sp. nov., from this salamander population. This chytrid causes erosive skin disease and rapid mortality in experimentally infected fire salamanders and was present in skin lesions of salamanders found dead during the decline event. Together with the closely related B. dendrobatidis, this taxon forms a well-supported chytridiomycete clade, adapted to vertebrate hosts and highly pathogenic to amphibians. However, the lower thermal growth preference of B. salamandrivorans, compared with B. dendrobatidis, and resistance of midwife toads (Alytes obstetricans) to experimental infection with B. salamandrivorans suggest differential niche occupation of the two chytrid fungi.

Unexpected metabolic disorders induced by endocrine disruptors in Xenopus tropicalis provide new lead for understanding amphibian decline.

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Regnault, Christophe; Usal, Marie; Veyrenc, Sylvie; Couturier, Karine; Batandier, Cécile; Bulteau, Anne-Laure; Lejon, David; Sapin, Alexandre; Combourieu, Bruno; Chetiveaux, Maud; Le May, Cédric; Lafond, Thomas; Raveton, Muriel; Reynaud, Stéphane

2018-05-08

Despite numerous studies suggesting that amphibians are highly sensitive to endocrine disruptors (EDs), both their role in the decline of populations and the underlying mechanisms remain unclear. This study showed that frogs exposed throughout their life cycle to ED concentrations low enough to be considered safe for drinking water, developed a prediabetes phenotype and, more commonly, a metabolic syndrome. Female Xenopus tropicalis exposed from tadpole stage to benzo( a )pyrene or triclosan at concentrations of 50 ng⋅L -1 displayed glucose intolerance syndrome, liver steatosis, liver mitochondrial dysfunction, liver transcriptomic signature, and pancreatic insulin hypersecretion, all typical of a prediabetes state. This metabolic syndrome led to progeny whose metamorphosis was delayed and occurred while the individuals were both smaller and lighter, all factors that have been linked to reduced adult recruitment and likelihood of reproduction. We found that F 1 animals did indeed have reduced reproductive success, demonstrating a lower fitness in ED-exposed Xenopus Moreover, after 1 year of depuration, Xenopus that had been exposed to benzo( a )pyrene still displayed hepatic disorders and a marked insulin secretory defect resulting in glucose intolerance. Our results demonstrate that amphibians are highly sensitive to EDs at concentrations well below the thresholds reported to induce stress in other vertebrates. This study introduces EDs as a possible key contributing factor to amphibian population decline through metabolism disruption. Overall, our results show that EDs cause metabolic disorders, which is in agreement with epidemiological studies suggesting that environmental EDs might be one of the principal causes of metabolic disease in humans.

Heterogeneous responses of temperate-zone amphibian populations to climate change complicates conservation planning

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Muths, Erin L.; Chambert, Thierry A.; Schmidt, B. R.; Miller, D. A. W.; Hossack, Blake R.; Joly, P.; Grolet, O.; Green, D. M.; Pilliod, David S.; Cheylan, M.; Fisher, Robert N.; McCaffery, R. M.; Adams, M. J.; Palen, W. J.; Arntzen, J. W.; Garwood, J.; Fellers, Gary M.; Thirion, J. M.; Grant, Evan H. Campbell; Besnard, A.

2017-01-01

The pervasive and unabated nature of global amphibian declines suggests common demographic responses to a given driver, and quantification of major drivers and responses could inform broad-scale conservation actions. We explored the influence of climate on demographic parameters (i.e., changes in the probabilities of survival and recruitment) using 31 datasets from temperate zone amphibian populations (North America and Europe) with more than a decade of observations each. There was evidence for an influence of climate on population demographic rates, but the direction and magnitude of responses to climate drivers was highly variable among taxa and among populations within taxa. These results reveal that climate drivers interact with variation in life-history traits and population-specific attributes resulting in a diversity of responses. This heterogeneity complicates the identification of conservation ‘rules of thumb’ for these taxa, and supports the notion of local focus as the most effective approach to overcome global-scale conservation challenges.

Differential host susceptibility to Batrachochytrium dendrobatidis, an emerging amphibian pathogen

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C.L. Searle; S.S. Gervasi; J. Hua; J.I. Hammond; R.A. Relyea; D.H. Olson; A.R. Blaustein

2011-01-01

The amphibian fungal pathogen Batrachochytrium dendrobatidis (Bd) has received considerable attention due to its role in amphibian population declines worldwide. Although many amphibian species appear to be affected by Bd, there is little information on species-specific differences in susceptibility to this pathogen. We used a comparative...

Climate change and amphibians

Science.gov (United States)

Corn, P.S.

2005-01-01

Amphibian life histories are exceedingly sensitive to temperature and precipitation, and there is good evidence that recent climate change has already resulted in a shift to breeding earlier in the year for some species. There are also suggestions that the recent increase in the occurrence of El Niño events has caused declines of anurans in Central America and is linked to elevated mortality of amphibian embryos in the northwestern United States. However, evidence linking amphibian declines in Central America to climate relies solely on correlations, and the mechanisms underlying the declines are not understood. Connections between embryo mortality and declines in abundance have not been demonstrated. Analyses of existing data have generally failed to find a link between climate and amphibian declines. It is likely, however, that future climate change will cause further declines of some amphibian species. Reduced soil moisture could reduce prey species and eliminate habitat. Reduced snowfall and increased summer evaporation could have dramatic effects on the duration or occurrence of seasonal wetlands, which are primary habitat for many species of amphibians. Climate change may be a relatively minor cause of current amphibian declines, but it may be the biggest future challenge to the persistence of many species

Climate change and amphibians

Directory of Open Access Journals (Sweden)

Corn, P. S.

2005-01-01

Full Text Available Amphibian life histories are exceedingly sensitive to temperature and precipitation, and there is good evidence that recent climate change has already resulted in a shift to breeding earlier in the year for some species. There are also suggestions that the recent increase in the occurrence of El Niño events has caused declines of anurans in Central America and is linked to elevated mortality of amphibian embryos in the northwestern United States. However, evidence linking amphibian declines in Central America to climate relies solely on correlations, and the mechanisms underlying the declines are not understood. Connections between embryo mortality and declines in abundance have not been demonstrated. Analyses of existing data have generally failed to find a link between climate and amphibian declines. It is likely, however, that future climate change will cause further declines of some amphibian species. Reduced soil moisture could reduce prey species and eliminate habitat. Reduced snowfall and increased summer evaporation could have dramatic effects on the duration or occurrence of seasonal wetlands, which are primary habitat for many species of amphibians. Climate change may be a relatively minor cause of current amphibian declines, but it may be the biggest future challenge to the persistence of many species

Synergism between UV-B radiation and pathogen magnifies amphibian embryo mortality in nature

International Nuclear Information System (INIS)

Kiesecker, J.M.; Blaustein, R.

1995-01-01

Previous research has shown that amphibians have differential sensitivity to ultraviolet-B (UV-B) radiation. In some species, ambient levels of UV-B radiation cause embryonic mortality in nature. The detrimental effects of UV-B alone or with other agents may ultimately affect amphibians at the population level. Here, we experimentally demonstrate a synergistic effect between UV-B radiation and a pathogenic fungus in the field that increases the mortality of amphibian embryos compared with either factor alone. Studies investigating single factors for causes of amphibian egg mortality or population declines may not reveal the complex factors involved in declines

Neotropical Amphibian Declines Affect Stream Ecosystem Properties

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Connelly, S.; Pringle, C. M.; Bixby, R. J.; Whiles, M. R.; Lips, K. R.; Brenes, R.; Colon-Gaud, J. C.; Kilham, S.; Hunte-Brown, M.

2005-05-01

Global declines of amphibians are well documented, yet effects of these dramatic losses on ecosystem structure and function are poorly understood. As part of a larger collaborative project, we compared two upland Panamanian streams. Both streams are biologically and geologically similar; however, one stream (Fortuna) has recently experienced almost complete extirpation of stream-dwelling frogs, while the other (Cope) still has intact populations. We experimentally excluded tadpoles from localized areas in each stream. We then compared chlorophyll a, algal community composition, ash-free dry mass (AFDM), inorganic matter, and insect assemblages in control and exclusion areas. Additionally, we sampled the natural substrate of both streams monthly for chlorophyll a, algal community composition, AFDM, and inorganic matter. At Cope, chlorophyll a, AFDM, and inorganic matter were greater in areas where tadpoles were excluded than in their presence. Numbers of dominant algal species (e.g., Nupela praecipua and Eunotia siolii) were greater in the exclusion versus control treatments. Monthly sampling of natural substrate indicated higher chlorophyll a and AFDM at Cope compared to Fortuna. Our data suggest that stream-dwelling anuran larvae have significant impacts on algal communities. These results also have implications for predicting the relevance of short-term experimental manipulations to long-term, whole-stream processes.

Mitigating amphibian chytridiomycosis in nature

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Garner, Trenton W. J.; Schmidt, Benedikt R.; Martel, An; Pasmans, Frank; Muths, Erin L.; Cunningham, Andrew A.; Weldon, Che; Fisher, Matthew C.; Bosch, Jaime

2016-01-01

Amphibians across the planet face the threat of population decline and extirpation caused by the disease chytridiomycosis. Despite consensus that the fungal pathogens responsible for the disease are conservation issues, strategies to mitigate their impacts in the natural world are, at best, nascent. Reducing risk associated with the movement of amphibians, non-amphibian vectors and other sources of infection remains the first line of defence and a primary objective when mitigating the threat of disease in wildlife. Amphibian-associated chytridiomycete fungi and chytridiomycosis are already widespread, though, and we therefore focus on discussing options for mitigating the threats once disease emergence has occurred in wild amphibian populations. All strategies have shortcomings that need to be overcome before implementation, including stronger efforts towards understanding and addressing ethical and legal considerations. Even if these issues can be dealt with, all currently available approaches, or those under discussion, are unlikely to yield the desired conservation outcome of disease mitigation. The decision process for establishing mitigation strategies requires integrated thinking that assesses disease mitigation options critically and embeds them within more comprehensive strategies for the conservation of amphibian populations, communities and ecosystems.

Quantitative evidence for the effects of multiple drivers on continental-scale amphibian declines

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Evan H. Campbell Grant; David A. W. Miller; Benedikt R. Schmidt; Michael J. Adams; Staci M. Amburgey; Thierry Chambert; Sam S. Cruickshank; Robert N. Fisher; David M. Green; Blake R. Hossack; Pieter T. J. Johnson; Maxwell B. Joseph; Tracy A. G. Rittenhouse; Maureen E. Ryan; J. Hardin Waddle; Susan C. Walls; Larissa L. Bailey; Gary M. Fellers; Thomas A. Gorman; Andrew M. Ray; David S. Pilliod; Steven J. Price; Daniel Saenz; Walt Sadinski; Erin Muths

2016-01-01

Since amphibian declines were first proposed as a global phenomenon over a quarter century ago, the conservation community has made little progress in halting or reversing these trends. The early search for a “smoking gun” was replaced with the expectation that declines are caused by multiple drivers. While field observations and experiments have identified factors...

Amphibian Population Sensitivity to Environmental and ...

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Anticipating chronic effects of contaminant exposure on amphibian species is complicated both by toxicological and ecological uncertainty. Data for both chemical exposures and amphibian vital rates, including altered growth, are sparse. Developmental plasticity in amphibians further complicates evaluation of chemical impacts as metamorphosis is also influenced by other biotic and abiotic stressors, such as temperature, hydroperiod, predation, and conspecific density. Determining the effect of delayed tadpole development on survival through metamorphosis and subsequent recruitment must include possible effects of pond drying accelerating metamorphosis near the end of the larval stage. This model considers the combined influence of delayed onset of metamorphosis in a cohort as well as accelerated metamorphosis toward the end of the hydroperiod and determines the net influence of counteracting forces on tadpole development and survival. Amphibian populations with greater initial density dependence have less capacity for developmental plasticity and are therefore more vulnerable to delayed development and reduced hydroperiod. The consequential reduction in larval survival has a relatively greater impact on species with a shorter lifespan, allowing for fewer breeding seasons during which to successfully produce offspring. In response to risk assessment approaches that consider only survival and reproductive endpoints in population evaluation, we calculate conta

Vulnerability of amphibians to climate change: implications for rangeland management

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Karen E. Bagne; Deborah M. Finch; Megan M. Friggens

2011-01-01

Many amphibian populations have declined drastically in recent years due to a large number of factors including the emerging threat of climate change (Wake 2007). Rangelands provide important habitat for amphibians. In addition to natural wetlands, stock tanks and other artificial water catchments provide habitat for many amphibian species (Euliss et al. 2004).

Correlated factors in amphibian decline: Exotic species and habitat change in western Washington

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Adams, Michael J.

1999-01-01

Amphibian declines may frequently be associated with multiple, correlated factors. In western North America, exotic species and hydrological changes are often correlated and are considered 2 of the greatest threats to freshwater systems. Bullfrog (Rana catesbeiana) introductions are frequently cited as a threat to lentic-breeding anurans native to western North America and are a suspected factor in the decline of red-legged frogs (Rana aurora) in California. Introduced fish and habitat change are cited less frequently but are equally viable hypotheses. I examined the relation among introduced species, habitat, and the distribution and abundance of red-legged frogs in western Washington. Red-legged frog occurrence in the Puget Lowlands was more closely associated with habitat structure and the presence of exotic fish than with the presence of bull-frogs. The spread of exotics is correlated with a shift toward greater permanence in wetland habitats regionally. Conservation of more ephemeral wetland habitats may have direct benefits for some native amphibians and may also reduce the threat of exotic fish and bullfrogs, both of which were associated with permanent wetlands. Research and conservation efforts for lowland anurans in the West should emphasize the complexities of multiple contributing factors to amphibian losses.

No evidence for effects of infection with the amphibian chytrid fungus on populations of yellow-bellied toads.

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Wagner, Norman; Neubeck, Claus; Guicking, Daniela; Finke, Lennart; Wittich, Martin; Weising, Kurt; Geske, Christian; Veith, Michael

2017-02-08

The parasitic chytrid fungus Batrachochytrium dendrobatidis (Bd) can cause the lethal disease chytridiomycosis in amphibians and therefore may play a role in population declines. The yellow-bellied toad Bombina variegata suffered strong declines throughout western and northwestern parts of its range and is therefore listed as highly endangered for Germany and the federal state of Hesse. Whether chytridiomycosis may play a role in the observed local declines of this strictly protected anuran species has never been tested. We investigated 19 Hessian yellow-bellied toad populations for Bd infection rates, conducted capture-mark-recapture studies in 4 of them over 2 to 3 yr, examined survival histories of recaptured infected individuals, and tested whether multi-locus heterozygosity of individuals as well as expected heterozygosity and different environmental variables of populations affect probabilities of Bd infection. Our results show high prevalence of Bd infection in Hessian yellow-bellied toad populations, but although significant decreases in 2 populations could be observed, no causative link to Bd as the reason for this can be established. Mass mortalities or obvious signs of disease in individuals were not observed. Conversely, we show that growth of Bd-infected populations is possible under favorable habitat conditions and that most infected individuals could be recaptured with improved body indices. Neither genetic diversity nor environmental variables appeared to affect Bd infection probabilities. Hence, genetically diverse amphibian specimens and populations may not automatically be less susceptible for Bd infection.

Effects of road mortality and mitigation measures on amphibian populations.

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Beebee, Trevor J C

2013-08-01

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.

Book review: The ecology and behavior of amphibians

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Walls, Susan C.

2008-01-01

This state‐of‐the‐art book has made its timely emergence amid a crisis of global magnitude: that of population declines, range reductions, and extinctions of numerous species of amphibians. A clear understanding of the fundamental concepts in amphibian biology is crucial to the success of any conservation effort. This volume compiles the information necessary to acquire that basic understanding. It is a comprehensive synthesis of both traditional and contemporary facets of amphibian biology, spanning a breadth of topics ranging from phylogeny, physiology, behavior, population and community ecology, and conservation. As such, it undoubtedly takes its place among contemporary volumes as the single, authoritative source for basic topics relevant to amphibian life.

Developmental responses of amphibians to solar and artificial UVB sources: a comparative study

International Nuclear Information System (INIS)

Hays, J.B.; Hoffman, P.D.; Pandelova, Iovanna; Coyle, Daniel

1996-01-01

Many amphibian species, in widely scattered locations, currently show population declines and/or reductions in range, but other amphibian species show no such declines. There is no known single cause for these declines. Differential sensitivity to UVB radiation among species might be one contributing factor. We have focused on amphibian eggs, potentially the most UVB-sensitive stage, and compared their resistance to UVB components of sunlight with their levels of photolyase, typically the most important enzyme for repair of the major UV photoproducts in DNA, cyclobutane pyrimidine dimers. (Author)

A new parameterization for integrated population models to document amphibian reintroductions.

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Duarte, Adam; Pearl, Christopher A; Adams, Michael J; Peterson, James T

2017-09-01

Managers are increasingly implementing reintroduction programs as part of a global effort to alleviate amphibian declines. Given uncertainty in factors affecting populations and a need to make recurring decisions to achieve objectives, adaptive management is a useful component of these efforts. A major impediment to the estimation of demographic rates often used to parameterize and refine decision-support models is that life-stage-specific monitoring data are frequently sparse for amphibians. We developed a new parameterization for integrated population models to match the ecology of amphibians and capitalize on relatively inexpensive monitoring data to document amphibian reintroductions. We evaluate the capability of this model by fitting it to Oregon spotted frog (Rana pretiosa) monitoring data collected from 2007 to 2014 following their reintroduction within the Klamath Basin, Oregon, USA. The number of egg masses encountered and the estimated adult and metamorph abundances generally increased following reintroduction. We found that survival probability from egg to metamorph ranged from 0.01 in 2008 to 0.09 in 2009 and was not related to minimum spring temperatures, metamorph survival probability ranged from 0.13 in 2010-2011 to 0.86 in 2012-2013 and was positively related to mean monthly temperatures (logit-scale slope = 2.37), adult survival probability was lower for founders (0.40) than individuals recruited after reintroduction (0.56), and the mean number of egg masses per adult female was 0.74. Our study is the first to test hypotheses concerning Oregon spotted frog egg-to-metamorph and metamorph-to-adult transition probabilities in the wild and document their response at multiple life stages following reintroduction. Furthermore, we provide an example to illustrate how the structure of our integrated population model serves as a useful foundation for amphibian decision-support models within adaptive management programs. The integration of multiple, but

Parallels in amphibian and bat declines from pathogenic fungi.

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Eskew, Evan A; Todd, Brian D

2013-03-01

Pathogenic fungi have substantial effects on global biodiversity, and 2 emerging pathogenic species-the chytridiomycete Batrachochytrium dendrobatidis, which causes chytridiomycosis in amphibians, and the ascomycete Geomyces destructans, which causes white-nose syndrome in hibernating bats-are implicated in the widespread decline of their vertebrate hosts. We synthesized current knowledge for chytridiomycosis and white-nose syndrome regarding disease emergence, environmental reservoirs, life history characteristics of the host, and host-pathogen interactions. We found striking similarities between these aspects of chytridiomycosis and white-nose syndrome, and the research that we review and propose should help guide management of future emerging fungal diseases.

Multiple stressors and amphibian declines: dual impacts of pesticides and fish on yellow-legged frogs.

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Davidson, Carlos; Knapp, Roland A

2007-03-01

More than 40% of Earth's 5700+ amphibian species have undergone recent declines. Despite the likely involvement of multiple factors in driving these declines, most studies continue to focus on single stressors. In California (USA), separate studies have implicated either introduced fish or pesticides as causal agents. To date, however, no study has simultaneously evaluated the respective roles of these two potential stressors nor attempted to assess their relative importance, information critical for the development of effective conservation efforts and environmental policies. We examined the role and relative effect of fish and pesticides on the mountain yellow-legged frog (Rana muscosa) using unusually detailed data sets for a large portion of R. muscosa's historic range in California's Sierra Nevada. Habitat characteristics and presence/absence of R. muscosa and fish were quantified at each of 6831 sites during field surveys. Pesticide use upwind of each site was calculated from pesticide application records and predominant wind directions. Using generalized additive models, we found that, after accounting for habitat effects, the probability of R. muscosa presence was significantly reduced by both fish and pesticides, with the landscape-scale effect of pesticides much stronger than that of fish. The degree to which a site was sheltered from the predominant wind (and associated pesticides) was also a significant predictor of R. muscosa presence. Taken together, these results represent the strongest evidence to date that windborne pesticides are contributing to amphibian declines in pristine locations. Our results suggest that amphibian declines may have complex multi-factorial causes, and caution that single-factor studies that demonstrate the importance of one factor should not be used as evidence against the importance of other factors.

Reservoir-host amplification of disease impact in an endangered amphibian.

Science.gov (United States)

Scheele, Ben C; Hunter, David A; Brannelly, Laura A; Skerratt, Lee F; Driscoll, Don A

2017-06-01

Emerging wildlife pathogens are an increasing threat to biodiversity. One of the most serious wildlife diseases is chytridiomycosis, caused by the fungal pathogen, Batrachochytrium dendrobatidis (Bd), which has been documented in over 500 amphibian species. Amphibians vary greatly in their susceptibility to Bd; some species tolerate infection, whereas others experience rapid mortality. Reservoir hosts-species that carry infection while maintaining high abundance but are rarely killed by disease-can increase extinction risk in highly susceptible, sympatric species. However, whether reservoir hosts amplify Bd in declining amphibian species has not been examined. We investigated the role of reservoir hosts in the decline of the threatened northern corroboree frog (Pseudophryne pengilleyi) in an amphibian community in southeastern Australia. In the laboratory, we characterized the response of a potential reservoir host, the (nondeclining) common eastern froglet (Crinia signifera), to Bd infection. In the field, we conducted frog abundance surveys and Bd sampling for both P. pengilleyi and C. signifera. We built multinomial logistic regression models to test whether Crinia signifera and environmental factors were associated with P. pengilleyi decline. C. signifera was a reservoir host for Bd. In the laboratory, many individuals maintained intense infections (>1000 zoospore equivalents) over 12 weeks without mortality, and 79% of individuals sampled in the wild also carried infections. The presence of C. signifera at a site was strongly associated with increased Bd prevalence in sympatric P. pengilleyi. Consistent with disease amplification by a reservoir host, P. pengilleyi declined at sites with high C. signifera abundance. Our results suggest that when reservoir hosts are present, population declines of susceptible species may continue long after the initial emergence of Bd, highlighting an urgent need to assess extinction risk in remnant populations of other declined

Reptiles and Amphibians of Fairchild Air Force Base, WA

Science.gov (United States)

2013-05-10

Reptiles and Amphibians of Fairchild Air Force Base, WA C on st ru ct io n E n gi n ee ri n g R es ea rc...online library at http://acwc.sdp.sirsi.net/client/default. ERDC/CERL TR-13-5 May 2013 Reptiles and Amphibians of Fairchild Air Force Base, WA...Washington, DC 20314-1000 ERDC/CERL TR-13-5 ii Abstract Many reptile and amphibian (collectively termed “herpetofauna”) populations are declining at

Modeling effects of conservation grassland losses on amphibian habitat

Science.gov (United States)

Mushet, David M.; Neau, Jordan L.; Euliss, Ned H.

2014-01-01

Amphibians provide many ecosystem services valued by society. However, populations have declined globally with most declines linked to habitat change. Wetlands and surrounding terrestrial grasslands form habitat for amphibians in the North American Prairie Pothole Region (PPR). Wetland drainage and grassland conversion have destroyed or degraded much amphibian habitat in the PPR. However, conservation grasslands can provide alternate habitat. In the United States, the Conservation Reserve Program (CRP) is the largest program maintaining grasslands on agricultural lands. We used an ecosystem services model (InVEST) parameterized for the PPR to quantify amphibian habitat over a six-year period (2007–2012). We then quantified changes in availability of amphibian habitat under various land-cover scenarios representing incremental losses (10%, 25%, 50%, 75%, and 100%) of CRP grasslands from 2012 levels. The area of optimal amphibian habitat in the four PPR ecoregions modeled (i.e., Northern Glaciated Plains, Northwestern Glaciated Plains, Lake Agassiz Plain, Des Moines Lobe) declined by approximately 22%, from 3.8 million ha in 2007 to 2.9 million ha in 2012. These losses were driven by the conversion of CRP grasslands to croplands, primarily for corn and soybean production. Our modeling identified an additional 0.8 million ha (26%) of optimal amphibian habitat that would be lost if remaining CRP lands are returned to crop production. An economic climate favoring commodity production over conservation has resulted in substantial losses of amphibian habitat across the PPR that will likely continue into the future. Other regions of the world face similar challenges to maintaining amphibian habitats.

Amphibians of the northern Great Plains

Science.gov (United States)

Larson, Diane L.; Euliss, Ned H.; Lannoo, Michael J.; Mushet, David M.; Mac, M.J.; Opler, P.A.; Puckett Haecker, C. E.; Doran, P.D.

1998-01-01

No cry of alarm has been sounded over the fate of amphibian populations in the northern grasslands of North America, yet huge percentages of prairie wetland habitat have been lost, and the destruction continues. Scarcely 30% of the original mixedgrass prairie remains in Nebraska, South Dakota, and North Dakota (See Table 1 in this chapter). If amphibian populations haven’t declined, why haven’t they? Or, have we simply failed to notice? Amphibians in the northern grasslands evolved in a boom-or-bust environment: species that were unable to survive droughts lasting for years died out long before humans were around to count them. Species we find today are expert at seizing the rare, wet moment to rebuild their populations in preparation for the next dry season. When numbers can change so rapidly, who can say if a species is rare or common? A lot depends on when you look.

Riding the wave: reconciling the roles of disease and climate change in amphibian declines.

Directory of Open Access Journals (Sweden)

Karen R Lips

2008-03-01

Full Text Available We review the evidence for the role of climate change in triggering disease outbreaks of chytridiomycosis, an emerging infectious disease of amphibians. Both climatic anomalies and disease-related extirpations are recent phenomena, and effects of both are especially noticeable at high elevations in tropical areas, making it difficult to determine whether they are operating separately or synergistically. We compiled reports of amphibian declines from Lower Central America and Andean South America to create maps and statistical models to test our hypothesis of spatiotemporal spread of the pathogen Batrachochytrium dendrobatidis (Bd, and to update the elevational patterns of decline in frogs belonging to the genus Atelopus. We evaluated claims of climate change influencing the spread of Bd by including error into estimates of the relationship between air temperature and last year observed. Available data support the hypothesis of multiple introductions of this invasive pathogen into South America and subsequent spread along the primary Andean cordilleras. Additional analyses found no evidence to support the hypothesis that climate change has been driving outbreaks of amphibian chytridiomycosis, as has been posited in the climate-linked epidemic hypothesis. Future studies should increase retrospective surveys of museum specimens from throughout the Andes and should study the landscape genetics of Bd to map fine-scale patterns of geographic spread to identify transmission routes and processes.

Riding the wave: reconciling the roles of disease and climate change in amphibian declines.

Science.gov (United States)

Lips, Karen R; Diffendorfer, Jay; Mendelson, Joseph R; Sears, Michael W

2008-03-25

We review the evidence for the role of climate change in triggering disease outbreaks of chytridiomycosis, an emerging infectious disease of amphibians. Both climatic anomalies and disease-related extirpations are recent phenomena, and effects of both are especially noticeable at high elevations in tropical areas, making it difficult to determine whether they are operating separately or synergistically. We compiled reports of amphibian declines from Lower Central America and Andean South America to create maps and statistical models to test our hypothesis of spatiotemporal spread of the pathogen Batrachochytrium dendrobatidis (Bd), and to update the elevational patterns of decline in frogs belonging to the genus Atelopus. We evaluated claims of climate change influencing the spread of Bd by including error into estimates of the relationship between air temperature and last year observed. Available data support the hypothesis of multiple introductions of this invasive pathogen into South America and subsequent spread along the primary Andean cordilleras. Additional analyses found no evidence to support the hypothesis that climate change has been driving outbreaks of amphibian chytridiomycosis, as has been posited in the climate-linked epidemic hypothesis. Future studies should increase retrospective surveys of museum specimens from throughout the Andes and should study the landscape genetics of Bd to map fine-scale patterns of geographic spread to identify transmission routes and processes.

Disease risk in temperate amphibian populations is higher at closed-canopy sites.

Directory of Open Access Journals (Sweden)

C Guilherme Becker

Full Text Available Habitat loss and chytridiomycosis (a disease caused by the chytrid fungus Batrachochytrium dendrobatidis - Bd are major drivers of amphibian declines worldwide. Habitat loss regulates host-pathogen interactions by altering biotic and abiotic factors directly linked to both host and pathogen fitness. Therefore, studies investigating the links between natural vegetation and chytridiomycosis require integrative approaches to control for the multitude of possible interactions of biological and environmental variables in spatial epidemiology. In this study, we quantified Bd infection dynamics across a gradient of natural vegetation and microclimates, looking for causal associations between vegetation cover, multiple microclimatic variables, and pathogen prevalence and infection intensity. To minimize the effects of host diversity in our analyses, we sampled amphibian populations in the Adirondack Mountains of New York State, a region with relatively high single-host dominance. We sampled permanent ponds for anurans, focusing on populations of the habitat generalist frog Lithobates clamitans, and recorded various biotic and abiotic factors that potentially affect host-pathogen interactions: natural vegetation, canopy density, water temperature, and host population and community attributes. We screened for important explanatory variables of Bd infections and used path analyses to statistically test for the strength of cascading effects linking vegetation cover, microclimate, and Bd parameters. We found that canopy density, natural vegetation, and daily average water temperature were the best predictors of Bd. High canopy density resulted in lower water temperature, which in turn predicted higher Bd prevalence and infection intensity. Our results confirm that microclimatic shifts arising from changes in natural vegetation play an important role in Bd spatial epidemiology, with areas of closed canopy favoring Bd. Given increasing rates of anthropogenic

Ecotoxicology of Amphibians and Reptiles

Science.gov (United States)

2000-01-01

For many years, ecological research on amphibians and reptiles has lagged behind that of other vertebrates such as fishes, birds, and mammals, despite the known importance of these animals in their environments. The lack of study has been particularly acute in the he area of ecotoxicology where the number of published scientific papers is a fraction of that found for the other vertebrate classes. Recently, scientists have become aware of severe crises among amphibian populations, including unexplained and sudden extinctions, worldwide declines, and hideous malformations. In many of these instances, contaminants have been listed as probable contributors. Data on the effects of contaminants on reptiles are so depauperate that even the most elementary interpretations are difficult. This state-of-the-science review and synthesis of amphibian and reptile ecotoxicology demonstrates the inter-relationships among distribution, ecology, physiology, and contaminant exposure, and interprets these topics as they pertain to comparative toxicity, population declines, malformations, and risk assessment . In this way, the book identifies and serves as a basis for the most pressing research needs in the coming years. The editors have invited 27 other internationally respected experts to examine the state of existing data in specific areas, interpret it in light of current problems, and identify research gaps and needs. Through its emphasis on recent research, extensive reviews and synthesis, Ecotoxicology of Amphibians and Reptiles will remain a definitive reference work well into the new century.

Airborne Pesticides as an Unlikely Cause for Population Declines of Alpine Frogs in the Sierra Nevada, California

Science.gov (United States)

Airborne pesticides from the Central Valley of California have been implicated as a cause for population declines of several amphibian species, with the strongest evidence for the mountain yellow-legged frog complex (Rana muscosa and R. sierrae) in the Sierra Nevada. We measured...

Climate change and amphibians

OpenAIRE

Corn, P. S.

2005-01-01

Amphibian life histories are exceedingly sensitive to temperature and precipitation, and there is good evidence that recent climate change has already resulted in a shift to breeding earlier in the year for some species. There are also suggestions that the recent increase in the occurrence of El Niño events has caused declines of anurans in Central America and is linked to elevated mortality of amphibian embryos in the northwestern United States. However, evidence linking amphibian declines i...

Amphibian monitoring in the Atchafalaya Basin

Science.gov (United States)

Waddle, Hardin

2011-01-01

Amphibians are a diverse group of animals that includes frogs, toads, and salamanders. They are adapted to living in a variety of habitats, but most require water for at least one life stage. Amphibians have recently become a worldwide conservation concern because of declines and extinctions even in remote protected areas previously thought to be safe from the pressures of habitat loss and degradation. Amphibians are an important part of ecosystem dynamics because they can be quite abundant and serve both as a predator of smaller organisms and as prey to a suite of vertebrate predators. Their permeable skin and aquatic life history also make them useful as indicators of ecosystem health. Since 2002, the U.S. Geological Survey has been studying the frog and toad species inhabiting the Atchafalaya Basin to monitor for population declines and to better understand how the species are potentially affected by disease, environmental contaminants, and climate change.

Batrachochytrium dendrobatidis infection patterns among Panamanian amphibian species, habitats and elevations during epizootic and enzootic stages.

Science.gov (United States)

Brem, Forrest M R; Lips, Karen R

2008-09-24

The pathogenic fungus Batrachochytrium dendrobatidis (Bd) has caused declines of many amphibian populations, yet the full course of the epizootic has rarely been observed in wild populations. We determined effects of elevation, habitat, and aquatic index (AI) on prevalence of infection among Panamanian amphibians sampled along 2 elevational transects. Amphibian populations on the Santa Fé transect (SFT) had declined in 2002, while those on the El Copé transect (ECT) were healthy until September 2004. In 2004 we sampled Bd along both transects, surveying the SFT 2 yr after decline, and surveying the ECT 4 mo prior to the arrival of Bd, during the epizootic, and 2 mo later. Overall prevalence of Bd along the ECT increased from 0.0 (95% CI 0.00-0.0003) to 0.51 (95% CI 0.48-0.55) over a 3 mo period, accompanied by significant decreases in amphibian abundance and species richness in all habitats. Prevalence of infection on the ECT was highest along riparian transects and at higher elevations, but not among levels of AI. Prevalence of infection on the SFT was highest in pool transects, and at higher elevations, but not among levels of AI. Riparian amphibian abundance and species richness also declined at SFT following detection of Bd in 2002. Variation among species, microenvironmental conditions, and the length of coexistence with Bd may contribute to observed differences in prevalence of Bd and in population response.

Effects of Roads on Amphibian Populations

DEFF Research Database (Denmark)

Hels, T.

is the result of my three year PhD study at the National Environmental Research Institute, Kalø, and University of Copenhagen. Funded by NERI, the Danish Research Academy, and the Danish Road Directorate, it has dealt mainly with the effects of traffic and roads on amphibian populations. The Spadefoot toad...... of Spadefoot toads (Pelobates fuscus Laur.) II The effect of road kills on amphibian populations III Simulating viability of a Spadefoot toad (P. fuscus) metapopulation in a landscape fragmented by a road The manuscripts are preceded by a synopsis which sums up the work and puts it into a broader perspective......, Johan Elmberg, Andreas Seiler, and Per Sjögren-Gulve, for sharing your knowledge and enthusiasm for science with me. Constructive ideas, different approaches, and elaborate discussions are crucial parts of any scientific process: I thank Lenore Fahrig for dedicated and original teaching and discussions...

Low prevalence of chytrid fungus (Batrachochytrium dendrobatidis) in amphibians of U.S

Science.gov (United States)

Blake R. Hossack; Michael J. Adams; Evan H. Campbell Grant; Christopher A. Pearl; James B. Bettaso; William J. Barichivich; Winsor H. Lowe; Kimberly True; Joy L. Ware; Paul Stephen Corn

2010-01-01

Many declines of amphibian populations have been associated with chytridiomycosis, a disease caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd). Despite the relatively high prevalence of chytridiomycosis in stream amphibians globally, most surveys in North America have focused primarily on wetland-associated species, which are frequently infected. To...

Overcoming challenges to the recovery of declining amphibian populations in the United States

Science.gov (United States)

Walls, Susan; Ball, Lianne C.; Barichivich, William J.; Dodd, Kenneth; Enge, Kevin M; Gorman, Thomas A.; O'Donnell, Katherine; Palis, John G; Semlitsch, Raymond D.

2016-01-01

The US Endangered Species Act of 1973 (ESA) affords many potential benefits to species threatened with extinction. However, most at-risk amphibians—one of the most imperiled vertebrate groups—remain unlisted under the provisions of the ESA, and many impediments to recovery exist for those species that have been listed. Of the 35 US amphibian species and distinct population segments (“taxa”) listed under the ESA, 40% currently lack a final (completed) recovery plan, 28.6% lack designated critical habitat, and 8.6% lack both. For taxa that have recovery plans, the time between their listing and the development of those plans was from 2 to 29 years, and the time between their listing and the designation of critical habitat ranged from 0 to 14 years. The underlying causes of such delays in protection are complex and constitute obstacles to recovery of imperiled species. We outline a series of strategic actions by which these challenges may be overcome.

OPTICAL CHARACTERISTICS OF NATURAL WATERS PROTECT AMPHIBIAN POPULATIONS FROM UV-B IN THE US PACIFIC NORTHWEST

Science.gov (United States)

Increased exposure to ultraviolet-B (UV-B) radiation has been proposed as a major environmental stressor leading to global amphibian declines. Prior experimental evidence from the US Pacific Northwest (PNW) indicating the acute embryonic sensitivity of at least 4 amphibian specie...

Correlates of virulence in a frog-killing fungal pathogen: evidence from a California amphibian decline

Science.gov (United States)

Jonah Piovia-Scott; Karen Pope; S. Joy Worth; Erica Bree Rosenblum; Dean Simon; Gordon Warburton; Louise A. Rollins-Smith; Laura K. Reinert; Heather L. Wells; Dan Rejmanek; Sharon Lawler; Janet Foley

2015-01-01

The fungal pathogen Batrachochytrium dendrobatidis (Bd) has caused declines and extinctions in amphibians worldwide, and there is increasing evidence that some strains of this pathogen are more virulent than others. While a number of putative virulence factors have been identified, few studies link these factors to specific epizootic events. We...

Spatial and temporal variation in population dynamics of Andean frogs: Effects of forest disturbance and evidence for declines

Directory of Open Access Journals (Sweden)

Esther M. Cole

2014-08-01

Full Text Available Biodiversity loss is a global phenomenon that can result in the collapse of food webs and critical ecosystem services. Amphibian population decline over the last century is a notable case of species loss because amphibians survived the last four major extinction events in global history, their current rate of extinction is unprecedented, and their rate of extinction is greater than that for most other taxonomic groups. Despite the severity of this conservation problem and its relevance to the study of global biodiversity loss, major knowledge gaps remain for many of the most threatened species and regions in the world. Rigorous estimates of population parameters are lacking for many amphibian species in the Neotropics. The goal of our study was to determine how the demography of seven species of the genus Pristimantis varied over time and space in two cloud forests in the Ecuadorian Andes. We completed a long term capture–mark–recapture study to estimate abundance, survival, and population growth rates in two cloud forests in the Ecuadorian Andes; from 2002 to 2009 at Yanayacu in the Eastern Cordillera and from 2002 to 2003 at Cashca Totoras in the Western Cordillera. Our results showed seasonal and annual variation in population parameters by species and sex. P. bicantus experienced significant reductions in abundance over the course of our study. Abundance, apparent survival, and population growth rates were lower in disturbed than in primary or mature secondary forest. The results of our study raise concerns for the population status of understudied amphibian groups and provide insights into the population dynamics of Neotropical amphibians.

Quantitative Proteomics of an Amphibian Pathogen, Batrachochytrium dendrobatidis, following Exposure to Thyroid Hormone

OpenAIRE

Thekkiniath, Jose; Zabet-Moghaddam, Masoud; Kottapalli, Kameswara Rao; Pasham, Mithun R.; San Francisco, Susan; San Francisco, Michael

2015-01-01

Batrachochytrium dendrobatidis (Bd), a chytrid fungus, has increasingly been implicated as a major factor in the worldwide decline of amphibian populations. The fungus causes chytridiomycosis in susceptible species leading to massive die-offs of adult amphibians. Although Bd infects the keratinized mouthparts of tadpoles and negatively affects foraging behavior, these infections are non-lethal. An important morphogen controlling amphibian metamorphosis is thyroid hormone (T3). Tadpoles may be...

Detecting the effects of environmentally relevant concentrations of thyroid hormone disrupting compounds on amphibian development

NARCIS (Netherlands)

Gutleb, A.C.

2006-01-01

Persistent organic pollutants such as PCBs have been hypothesized to contribute to the observed global decline of amphibian populations. Thyroid hormone (TH) disruption is one of the possible mechanisms for effects of xenobiotics on amphibian development. In addition to the important functions

HISTORY OF AMPHIBIAN DECLINE AND THE PAST, PRESENT AND FUTURE RESEARCH WITH UV LIGHT AND OTHER STRESSORS

Science.gov (United States)

This talk is an overview of the history of amphibian decline and the lab research and field monitoring results generated by MED and other agencies. Included are the general field observations leading up to our research initiation, UV-light exposures to the Northern Leopard Frog...

Dramatic Declines of Montane Frogs in a Central African Biodiversity Hotspot

Science.gov (United States)

Hirschfeld, Mareike; Blackburn, David C.; Doherty-Bone, Thomas M.; Gonwouo, LeGrand Nono; Ghose, Sonia; Rödel, Mark-Oliver

2016-01-01

Amphibian populations are vanishing worldwide. Declines and extinctions of many populations have been attributed to chytridiomycosis, a disease induced by the pathogenic fungus Batrachochytrium dendrobatidis (Bd). In Africa, however, changes in amphibian assemblages were typically attributed to habitat change. We conducted a retrospective study utilizing field surveys from 2004–2012 of the anuran faunas on two mountains in western Cameroon, a hotspot of African amphibian diversity. The number of species detected was negatively influenced by year, habitat degradation, and elevation, and we detected a decline of certain species. Because another study in this region revealed an emergence of Bd in 2008, we screened additional recent field-collected samples and also pre-decline preserved museum specimens for the presence of Bd supporting emergence before 2008. When comparing the years before and after Bd detection, we found significantly diminished frog species richness and abundance on both mountains after Bd emergence. Our analyses suggest that this may be the first disease-driven community-level decline in anuran biodiversity in Central Africa. The disappearance of several species known to tolerate habitat degradation, and a trend of stronger declines at higher elevations, are consistent with Bd-induced declines in other regions. Not all species decreased; populations of some species remained constant, and others increased after the emergence of Bd. This variation might be explained by species-specific differences in infection probability. Increased habitat protection and Bd-mitigation strategies are needed for sustaining diverse amphibian communities such as those on Mt. Manengouba, which contains nearly half of Cameroon’s frog diversity. PMID:27149624

Dramatic Declines of Montane Frogs in a Central African Biodiversity Hotspot.

Directory of Open Access Journals (Sweden)

Mareike Hirschfeld

Full Text Available Amphibian populations are vanishing worldwide. Declines and extinctions of many populations have been attributed to chytridiomycosis, a disease induced by the pathogenic fungus Batrachochytrium dendrobatidis (Bd. In Africa, however, changes in amphibian assemblages were typically attributed to habitat change. We conducted a retrospective study utilizing field surveys from 2004-2012 of the anuran faunas on two mountains in western Cameroon, a hotspot of African amphibian diversity. The number of species detected was negatively influenced by year, habitat degradation, and elevation, and we detected a decline of certain species. Because another study in this region revealed an emergence of Bd in 2008, we screened additional recent field-collected samples and also pre-decline preserved museum specimens for the presence of Bd supporting emergence before 2008. When comparing the years before and after Bd detection, we found significantly diminished frog species richness and abundance on both mountains after Bd emergence. Our analyses suggest that this may be the first disease-driven community-level decline in anuran biodiversity in Central Africa. The disappearance of several species known to tolerate habitat degradation, and a trend of stronger declines at higher elevations, are consistent with Bd-induced declines in other regions. Not all species decreased; populations of some species remained constant, and others increased after the emergence of Bd. This variation might be explained by species-specific differences in infection probability. Increased habitat protection and Bd-mitigation strategies are needed for sustaining diverse amphibian communities such as those on Mt. Manengouba, which contains nearly half of Cameroon's frog diversity.

Large-scale recovery of an endangered amphibian despite ongoing exposure to multiple stressors

Science.gov (United States)

Knapp, Roland A.; Fellers, Gary M.; Kleeman, Patrick M.; Miller, David A. W.; Vrendenburg, Vance T.; Rosenblum, Erica Bree; Briggs, Cheryl J.

2016-01-01

Amphibians are one of the most threatened animal groups, with 32% of species at risk for extinction. Given this imperiled status, is the disappearance of a large fraction of the Earth’s amphibians inevitable, or are some declining species more resilient than is generally assumed? We address this question in a species that is emblematic of many declining amphibians, the endangered Sierra Nevada yellow-legged frog (Rana sierrae). Based on >7,000 frog surveys conducted across Yosemite National Park over a 20-y period, we show that, after decades of decline and despite ongoing exposure to multiple stressors, including introduced fish, the recently emerged disease chytridiomycosis, and pesticides, R. sierrae abundance increased sevenfold during the study and at a rate of 11% per year. These increases occurred in hundreds of populations throughout Yosemite, providing a rare example of amphibian recovery at an ecologically relevant spatial scale. Results from a laboratory experiment indicate that these increases may be in part because of reduced frog susceptibility to chytridiomycosis. The disappearance of nonnative fish from numerous water bodies after cessation of stocking also contributed to the recovery. The large-scale increases in R. sierrae abundance that we document suggest that, when habitats are relatively intact and stressors are reduced in their importance by active management or species’ adaptive responses, declines of some amphibians may be partially reversible, at least at a regional scale. Other studies conducted over similarly large temporal and spatial scales are critically needed to provide insight and generality about the reversibility of amphibian declines at a global scale.

Do hormone-modulating chemicals impact on reproduction and development of wild amphibians?

Science.gov (United States)

Orton, Frances; Tyler, Charles R

2015-11-01

Globally, amphibians are undergoing a precipitous decline. At the last estimate in 2004, 32% of the approximately 6000 species were threatened with extinction and 43% were experiencing significant declines. These declines have been linked with a wide range of environmental pressures from habitat loss to climate change, disease and pollution. This review evaluates the evidence that endocrine-disrupting contaminants (EDCs) - pollutants that affect hormone systems - are impacting on wild amphibians and contributing to population declines. The review is limited to anurans (frogs and toads) as data for effects of EDCs on wild urodeles (salamanders, newts) or caecilians (limbless amphibians) are extremely limited. Evidence from laboratory studies has shown that a wide range of chemicals have the ability to alter hormone systems and affect reproductive development and function in anurans, but for the most part only at concentrations exceeding those normally found in natural environments. Exceptions can be found for exposures to the herbicide atrazine and polychlorinated biphenyls in leopard frogs (Rana pipiens) and perchlorate in African clawed frogs (Xenopus laevis). These contaminants induce feminising effects on the male gonads (including 'intersex' - oocytes within testes) at concentrations measured in some aquatic environments. The most extensive data for effects of an EDC in wild amphibian populations are for feminising effects of atrazine on male gonad development in regions across the USA. Even where strong evidence has been provided for feminising effects of EDCs, however, the possible impact of these effects on fertility and breeding outcome has not been established, making inference for effects on populations difficult. Laboratory studies have shown that various chemicals, including perchlorate, polychlorinated biphenyls and bromodiphenylethers, also act as endocrine disrupters through interfering with thyroid-dependent processes that are fundamental for

Amphibians and plant-protection products: what research and action is needed?

Science.gov (United States)

Aldrich, Annette; Junghans, Marion; Aeberli, Caroline; Brühl, Carsten A; Streissl, Franz; Schmidt, Benedikt R

2016-01-01

The majority of Swiss amphibians are threatened. There is a range of factors which have been discussed as possible causes for their decline, including plant protection products (PPPs). The influence of PPPs on amphibian populations has not yet been studied to any great extent, neither for active ingredients nor for the wetting agents, breakdown products or tank mixtures. A further topic of discussion was how to better protect amphibians by reducing their exposure to PPPs in agricultural fields. Experts at a workshop concluded that further research is needed.

Differences in sensitivity to the fungal pathogen Batrachochytrium dendrobatidis among amphibian populations.

Science.gov (United States)

Bradley, Paul W; Gervasi, Stephanie S; Hua, Jessica; Cothran, Rickey D; Relyea, Rick A; Olson, Deanna H; Blaustein, Andrew R

2015-10-01

Contributing to the worldwide biodiversity crisis are emerging infectious diseases, which can lead to extirpations and extinctions of hosts. For example, the infectious fungal pathogen Batrachochytrium dendrobatidis (Bd) is associated with worldwide amphibian population declines and extinctions. Sensitivity to Bd varies with species, season, and life stage. However, there is little information on whether sensitivity to Bd differs among populations, which is essential for understanding Bd-infection dynamics and for formulating conservation strategies. We experimentally investigated intraspecific differences in host sensitivity to Bd across 10 populations of wood frogs (Lithobates sylvaticus) raised from eggs to metamorphosis. We exposed the post-metamorphic wood frogs to Bd and monitored survival for 30 days under controlled laboratory conditions. Populations differed in overall survival and mortality rate. Infection load also differed among populations but was not correlated with population differences in risk of mortality. Such population-level variation in sensitivity to Bd may result in reservoir populations that may be a source for the transmission of Bd to other sensitive populations or species. Alternatively, remnant populations that are less sensitive to Bd could serve as sources for recolonization after epidemic events. © 2015 Society for Conservation Biology.

Restored agricultural wetlands in Central Iowa: habitat quality and amphibian response

Science.gov (United States)

Reeves, Rebecca A.; Pierce, Clay; Smalling, Kelly L.; Klaver, Robert W.; Vandever, Mark W.; Battaglin, William A.; Muths, Erin L.

2016-01-01

Amphibians are declining throughout the United States and worldwide due, partly, to habitat loss. Conservation practices on the landscape restore wetlands to denitrify tile drainage effluent and restore ecosystem services. Understanding how water quality, hydroperiod, predation, and disease affect amphibians in restored wetlands is central to maintaining healthy amphibian populations in the region. We examined the quality of amphibian habitat in restored wetlands relative to reference wetlands by comparing species richness, developmental stress, and adult leopard frog (Lithobates pipiens) survival probabilities to a suite of environmental metrics. Although measured habitat variables differed between restored and reference wetlands, differences appeared to have sub-lethal rather than lethal effects on resident amphibian populations. There were few differences in amphibian species richness and no difference in estimated survival probabilities between wetland types. Restored wetlands had more nitrate and alkaline pH, longer hydroperiods, and were deeper, whereas reference wetlands had more amphibian chytrid fungus zoospores in water samples and resident amphibians exhibited increased developmental stress. Restored and reference wetlands are both important components of the landscape in central Iowa and maintaining a complex of fish-free wetlands with a variety of hydroperiods will likely contribute to the persistence of amphibians in this landscape.

Epidemic disease decimates amphibian abundance, species diversity, and evolutionary history in the highlands of central Panama.

Science.gov (United States)

Crawford, Andrew J; Lips, Karen R; Bermingham, Eldredge

2010-08-03

Amphibian populations around the world are experiencing unprecedented declines attributed to a chytrid fungal pathogen, Batrachochytrium dendrobatidis. Despite the severity of the crisis, quantitative analyses of the effects of the epidemic on amphibian abundance and diversity have been unavailable as a result of the lack of equivalent data collected before and following disease outbreak. We present a community-level assessment combining long-term field surveys and DNA barcode data describing changes in abundance and evolutionary diversity within the amphibian community of El Copé, Panama, following a disease epidemic and mass-mortality event. The epidemic reduced taxonomic, lineage, and phylogenetic diversity similarly. We discovered that 30 species were lost, including five undescribed species, representing 41% of total amphibian lineage diversity in El Copé. These extirpations represented 33% of the evolutionary history of amphibians within the community, and variation in the degree of population loss and decline among species was random with respect to the community phylogeny. Our approach provides a fast, economical, and informative analysis of loss in a community whether measured by species or phylogenetic diversity.

Effects of amphibian chytrid fungus on individual survival probability in wild boreal toads

Science.gov (United States)

Pilliod, D.S.; Muths, E.; Scherer, R. D.; Bartelt, P.E.; Corn, P.S.; Hossack, B.R.; Lambert, B.A.; Mccaffery, R.; Gaughan, C.

2010-01-01

Chytridiomycosis is linked to the worldwide decline of amphibians, yet little is known about the demographic effects of the disease. We collected capture-recapture data on three populations of boreal toads (Bufo boreas [Bufo = Anaxyrus]) in the Rocky Mountains (U.S.A.). Two of the populations were infected with chytridiomycosis and one was not. We examined the effect of the presence of amphibian chytrid fungus (Batrachochytrium dendrobatidis [Bd]; the agent of chytridiomycosis) on survival probability and population growth rate. Toads that were infected with Bd had lower average annual survival probability than uninfected individuals at sites where Bd was detected, which suggests chytridiomycosis may reduce survival by 31-42% in wild boreal toads. Toads that were negative for Bd at infected sites had survival probabilities comparable to toads at the uninfected site. Evidence that environmental covariates (particularly cold temperatures during the breeding season) influenced toad survival was weak. The number of individuals in diseased populations declined by 5-7%/year over the 6 years of the study, whereas the uninfected population had comparatively stable population growth. Our data suggest that the presence of Bd in these toad populations is not causing rapid population declines. Rather, chytridiomycosis appears to be functioning as a low-level, chronic disease whereby some infected individuals survive but the overall population effects are still negative. Our results show that some amphibian populations may be coexisting with Bd and highlight the importance of quantitative assessments of survival in diseased animal populations. Journal compilation. ?? 2010 Society for Conservation Biology. No claim to original US government works.

Questions concerning the potential impact of glyphosate-based herbicides on amphibians.

Science.gov (United States)

Wagner, Norman; Reichenbecher, Wolfram; Teichmann, Hanka; Tappeser, Beatrix; Lötters, Stefan

2013-08-01

Use of glyphosate-based herbicides is increasing worldwide. The authors review the available data related to potential impacts of these herbicides on amphibians and conduct a qualitative meta-analysis. Because little is known about environmental concentrations of glyphosate in amphibian habitats and virtually nothing is known about environmental concentrations of the substances added to the herbicide formulations that mainly contribute to adverse effects, glyphosate levels can only be seen as approximations for contamination with glyphosate-based herbicides. The impact on amphibians depends on the herbicide formulation, with different sensitivity of taxa and life stages. Effects on development of larvae apparently are the most sensitive endpoints to study. As with other contaminants, costressors mainly increase adverse effects. If and how glyphosate-based herbicides and other pesticides contribute to amphibian decline is not answerable yet due to missing data on how natural populations are affected. Amphibian risk assessment can only be conducted case-specifically, with consideration of the particular herbicide formulation. The authors recommend better monitoring of both amphibian populations and contamination of habitats with glyphosate-based herbicides, not just glyphosate, and suggest including amphibians in standardized test batteries to study at least dermal administration. Copyright © 2013 SETAC.

Batrachochytrium salamandrivorans and the risk of a second amphibian pandemic

Science.gov (United States)

Yap, Tiffany A.; Nguyen, Natalie T.; Serr, Megan; Shepak, Alex; Vredenburg, Vance

2017-01-01

Amphibians are experiencing devastating population declines globally. A major driver is chytridiomycosis, an emerging infectious disease caused by the fungal pathogens Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal). Bdwas described in 1999 and has been linked with declines since the 1970s, while Bsal is a more recently discovered pathogen that was described in 2013. It is hypothesized that Bsaloriginated in Asia and spread via international trade to Europe, where it has been linked to salamander die-offs. Trade in live amphibians thus represents a significant threat to global biodiversity in amphibians. We review the current state of knowledge regarding Bsal and describe the risk of Bsal spread. We discuss regional responses to Bsal and barriers that impede a rapid, coordinated global effort. The discovery of a second deadly emerging chytrid fungal pathogen in amphibians poses an opportunity for scientists, conservationists, and governments to improve global biosecurity and further protect humans and wildlife from a growing number of emerging infectious diseases.

An alternative framework for responding to the amphibian crisis

Science.gov (United States)

Muths, Erin L.; Fisher, Robert N.

2017-01-01

Volumes of data illustrate the severity of the crisis affecting amphibians, where > 32% of amphibians worldwide are threatened with declining populations. Although there have been isolated victories, the current approach to the issue is unsuccessful. We suggest that a radically different approach, something akin to human emergency response management (i.e. the Incident Command System), is one alternative to addressing the inertia and lack of cohesion in responding to amphibian issues. We acknowledge existing efforts and the useful research that has been conducted, but we suggest that a change is warranted and that the identification of a new amphibian chytrid provides the impetus for such a change. Our goal is to recognize that without a centralized effort we (collectively) are likely to fail in responding to this challenge.

Histological evidence of chytridiomycete fungal infection in a free-ranging amphibian, Afrana fuscigula (Anura: Ranidae), in South Africa : short communication

OpenAIRE

E.P. Lane; C. Weldon; J. Bingham

2003-01-01

The 1st recorded histological evidence of chytridiomycete fungal infection in a free-ranging ranid amphibian in South Africa is presented. Literature on causes of a worldwide decline in amphibian populations is briefly reviewed.

Histological evidence of chytridiomycete fungal infection in a free-ranging amphibian, Afrana fuscigula (Anura: Ranidae, in South Africa : short communication

Directory of Open Access Journals (Sweden)

E.P. Lane

2003-06-01

Full Text Available The 1st recorded histological evidence of chytridiomycete fungal infection in a free-ranging ranid amphibian in South Africa is presented. Literature on causes of a worldwide decline in amphibian populations is briefly reviewed.

Analysis of a Mathematical Model of Emerging Infectious Disease Leading to Amphibian Decline

OpenAIRE

Dur-e-Ahmad, Muhammad; Imran, Mudassar; Khan, Adnan

2014-01-01

We formulate a three-dimensional deterministic model of amphibian larvae population to investigate the cause of extinction due to the infectious disease. The larvae population of the model is subdivided into two classes, exposed and unexposed, depending on their vulnerability to disease. Reproduction ratio ${\\scr R}_{0}$ has been calculated and we have shown that if ${\\scr R}_{0}1$ , we discussed different scenarios under which an infected population can survive or be eliminated using stabili...

Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Wild Amphibian Populations in Madagascar

Science.gov (United States)

Kolby, Jonathan E.; Smith, Kristine M.; Ramirez, Sara D.; Rabemananjara, Falitiana; Pessier, Allan P.; Brunner, Jesse L.; Goldberg, Caren S.; Berger, Lee; Skerratt, Lee F.

2015-01-01

. Standardized population monitoring of key amphibian and reptile species should be established with urgency to enable early detection of potential impacts of disease emergence in this global biodiversity hotspot. PMID:26083349

Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis and Ranavirus in Wild Amphibian Populations in Madagascar.

Directory of Open Access Journals (Sweden)

Jonathan E Kolby

disease. Standardized population monitoring of key amphibian and reptile species should be established with urgency to enable early detection of potential impacts of disease emergence in this global biodiversity hotspot.

Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Wild Amphibian Populations in Madagascar.

Science.gov (United States)

Kolby, Jonathan E; Smith, Kristine M; Ramirez, Sara D; Rabemananjara, Falitiana; Pessier, Allan P; Brunner, Jesse L; Goldberg, Caren S; Berger, Lee; Skerratt, Lee F

2015-01-01

. Standardized population monitoring of key amphibian and reptile species should be established with urgency to enable early detection of potential impacts of disease emergence in this global biodiversity hotspot.

Species-level correlates of susceptibility to the pathogenic amphibian fungus Batrachochytrium dendrobatidis in the United States

Science.gov (United States)

Betsy A. Bancroft; Barbara A. Han; Catherine L. Searle; Lindsay M. Biga; Deanna H. Olson; Lee B. Kats; Joshua J. Lawler; Andrew R. Blaustein

2011-01-01

Disease is often implicated as a factor in population declines of wildlife and plants. Understanding the characteristics that may predispose a species to infection by a particular pathogen can help direct conservation efforts. Recent declines in amphibian populations world-wide are a major conservation issue and may be caused in part by a fungal pathogen, ...

Amphibians at risk? Susceptibility of terrestrial amphibian life stages to pesticides.

Science.gov (United States)

Brühl, Carsten A; Pieper, Silvia; Weber, Brigitte

2011-11-01

Current pesticide risk assessment does not specifically consider amphibians. Amphibians in the aquatic environment (aquatic life stages or postmetamorphic aquatic amphibians) and terrestrial living juvenile or adult amphibians are assumed to be covered by the risk assessment for aquatic invertebrates and fish, or mammals and birds, respectively. This procedure has been evaluated as being sufficiently protective regarding the acute risk posed by a number of pesticides to aquatic amphibian life stages (eggs, larvae). However, it is unknown whether the exposure and sensitivity of terrestrial living amphibians are comparable to mammalian and avian exposure and sensitivity. We reviewed the literature on dermal pesticide absorption and toxicity studies for terrestrial life stages of amphibians, focusing on the dermal exposure pathway, that is, through treated soil or direct overspray. In vitro studies demonstrated that cutaneous absorption of chemicals is significant and that chemical percutaneous passage, P (cm/h), is higher in amphibians than in mammals. In vivo, the rapid and substantial uptake of the herbicide atrazine from treated soil by toads (Bufo americanus) has been described. Severe toxic effects on various amphibian species have been reported for field-relevant application rates of different pesticides. In general, exposure and toxicity studies for terrestrial amphibian life stages are scarce, and the reported data indicate the need for further research, especially in light of the global amphibian decline. Copyright © 2011 SETAC.

Looking for attitudes related to amphibian species decline: how are peer-reviewed publications of education activities compared to ecological research?

Science.gov (United States)

Mormul, Roger P; Mormul, Tayla D S; Santos, Gustavo M B; Santana, Ana R A

2017-05-01

Biodiversity decline has been the focus of discussions in the last decade, especially on the amphibian species decline. After a scientometric analysis using international databases, we found that the number of peer-reviewed articles considering education practices related to the theme increased along with the number of ecological researches. However, the increase in ecological researches is much higher than the increase in publications of education practices. Studies suggest that conservation attitudes are important and that education practices are an important tool for improving human perceptions on this subject. In this sense, increase the publication of projects and programs results related to local education practices in international journals could help the dissemination of efficient methods for conservation, as well as facilitating access to information internationally, since species decline, especially for amphibians, is a global concern. Then, we suggest that educational practices, at least when related to conservation, should follow a more standardized protocol, and be published in international journals, as the efficiency of such practices should be evaluated and methods once published could help other nations to improve their ecological literacy.

Estimating Herd Immunity to Amphibian Chytridiomycosis in Madagascar Based on the Defensive Function of Amphibian Skin Bacteria

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Molly C. Bletz

2017-09-01

Full Text Available For decades, Amphibians have been globally threatened by the still expanding infectious disease, chytridiomycosis. Madagascar is an amphibian biodiversity hotspot where Batrachochytrium dendrobatidis (Bd has only recently been detected. While no Bd-associated population declines have been reported, the risk of declines is high when invasive virulent lineages become involved. Cutaneous bacteria contribute to host innate immunity by providing defense against pathogens for numerous animals, including amphibians. Little is known, however, about the cutaneous bacterial residents of Malagasy amphibians and the functional capacity they have against Bd. We cultured 3179 skin bacterial isolates from over 90 frog species across Madagascar, identified them via Sanger sequencing of approximately 700 bp of the 16S rRNA gene, and characterized their functional capacity against Bd. A subset of isolates was also tested against multiple Bd genotypes. In addition, we applied the concept of herd immunity to estimate Bd-associated risk for amphibian communities across Madagascar based on bacterial antifungal activity. We found that multiple bacterial isolates (39% of all isolates cultured from the skin of Malagasy frogs were able to inhibit Bd. Mean inhibition was weakly correlated with bacterial phylogeny, and certain taxonomic groups appear to have a high proportion of inhibitory isolates, such as the Enterobacteriaceae, Pseudomonadaceae, and Xanthamonadaceae (84, 80, and 75% respectively. Functional capacity of bacteria against Bd varied among Bd genotypes; however, there were some bacteria that showed broad spectrum inhibition against all tested Bd genotypes, suggesting that these bacteria would be good candidates for probiotic therapies. We estimated Bd-associated risk for sampled amphibian communities based on the concept of herd immunity. Multiple amphibian communities, including those in the amphibian diversity hotspots, Andasibe and Ranomafana, were

Estimating Herd Immunity to Amphibian Chytridiomycosis in Madagascar Based on the Defensive Function of Amphibian Skin Bacteria.

Science.gov (United States)

Bletz, Molly C; Myers, Jillian; Woodhams, Douglas C; Rabemananjara, Falitiana C E; Rakotonirina, Angela; Weldon, Che; Edmonds, Devin; Vences, Miguel; Harris, Reid N

2017-01-01

For decades, Amphibians have been globally threatened by the still expanding infectious disease, chytridiomycosis. Madagascar is an amphibian biodiversity hotspot where Batrachochytrium dendrobatidis ( Bd ) has only recently been detected. While no Bd -associated population declines have been reported, the risk of declines is high when invasive virulent lineages become involved. Cutaneous bacteria contribute to host innate immunity by providing defense against pathogens for numerous animals, including amphibians. Little is known, however, about the cutaneous bacterial residents of Malagasy amphibians and the functional capacity they have against Bd . We cultured 3179 skin bacterial isolates from over 90 frog species across Madagascar, identified them via Sanger sequencing of approximately 700 bp of the 16S rRNA gene, and characterized their functional capacity against Bd . A subset of isolates was also tested against multiple Bd genotypes. In addition, we applied the concept of herd immunity to estimate Bd -associated risk for amphibian communities across Madagascar based on bacterial antifungal activity. We found that multiple bacterial isolates (39% of all isolates) cultured from the skin of Malagasy frogs were able to inhibit Bd . Mean inhibition was weakly correlated with bacterial phylogeny, and certain taxonomic groups appear to have a high proportion of inhibitory isolates, such as the Enterobacteriaceae, Pseudomonadaceae, and Xanthamonadaceae (84, 80, and 75% respectively). Functional capacity of bacteria against Bd varied among Bd genotypes; however, there were some bacteria that showed broad spectrum inhibition against all tested Bd genotypes, suggesting that these bacteria would be good candidates for probiotic therapies. We estimated Bd -associated risk for sampled amphibian communities based on the concept of herd immunity. Multiple amphibian communities, including those in the amphibian diversity hotspots, Andasibe and Ranomafana, were estimated to be

Sex Reversal in Amphibians.

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Flament, Stéphane

2016-01-01

Amphibians have been widely used to study developmental biology due to the fact that embryo development takes place independently of the maternal organism and that observations and experimental approaches are easy. Some amphibians like Xenopus became model organisms in this field. In the first part of this article, the differentiation of the gonads in amphibians and the mechanisms governing this process are reviewed. In the second part, the state of the art about sex reversal, which can be induced by steroid hormones in general and by temperature in some species, is presented. Also information about pollutants found in the environment that could interfere with the development of the amphibian reproductive apparatus or with their reproductive physiology is given. Such compounds could play a part in the amphibian decline, since in the wild, many amphibians are endangered species. © 2016 S. Karger AG, Basel.

Toward immunogenetic studies of amphibian chytridiomycosis: Linking innate and acquired immunity

Science.gov (United States)

Richmond, J.Q.; Savage, Anna E.; Zamudio, Kelly R.; Rosenblum, E.B.

2009-01-01

Recent declines in amphibian diversity and abundance have contributed significantly to the global loss of biodiversity. The fungal disease chytridiomycosis is widely considered to be a primary cause of these declines, yet the critical question of why amphibian species differ in susceptibility remains unanswered. Considerable evidence links environmental conditions and interspecific variability of the innate immune system to differential infection responses, but other sources of individual, population, or species-typical variation may also be important. In this article we review the preliminary evidence supporting a role for acquired immune defenses against chytridiomycosis, and advocate for targeted investigation of genes controlling acquired responses, as well as those that functionally bridge the innate and acquired immune systems. Immunogenetic data promise to answer key questions about chytridiomycosis susceptibility and host-pathogen coevolution, and will draw much needed attention to the importance of considering evolutionary processes in amphibian conservation management and practice. ?? 2009 by American Institute of Biological Sciences.

Additive threats from pathogens, climate and land-use change for global amphibian diversity

DEFF Research Database (Denmark)

Hof, Christian; Bastos Araujo, Miguel; Jetz, Walter

2011-01-01

Amphibian population declines far exceed those of other vertebrate groups, with 30% of all species listed as threatened by the International Union for Conservation of Nature. The causes of these declines are a matter of continued research, but probably include climate change, land-use change...... to be found in Africa, parts of northern South America and the Andes. Regions with the highest projected impact of land-use and climate change coincide, but there is little spatial overlap with regions highly threatened by the fungal disease. Overall, the areas harbouring the richest amphibian faunas...... and spread of the pathogenic fungal disease chytridiomycosis. Here we assess the spatial distribution and interactions of these primary threats in relation to the global distribution of amphibian species. We show that the greatest proportions of species negatively affected by climate change are projected...

Use of multiple dispersal pathways facilitates amphibian persistence in stream networks

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Campbell, Grant E.H.; Nichols, J.D.; Lowe, W.H.; Fagan, W.F.

2010-01-01

Although populations of amphibians are declining worldwide, there is no evidence that salamanders occupying small streams are experiencing enigmatic declines, and populations of these species seem stable. Theory predicts that dispersal through multiple pathways can stabilize populations, preventing extinction in habitat networks. However, empirical data to support this prediction are absent for most species, especially those at risk of decline. Our mark-recapture study of stream salamanders reveals both a strong upstream bias in dispersal and a surprisingly high rate of overland dispersal to adjacent headwater streams. This evidence of route-dependent variation in dispersal rates suggests a spatial mechanism for population stability in headwater-stream salamanders. Our results link the movement behavior of stream salamanders to network topology, and they underscore the importance of identifying and protecting critical dispersal pathways when addressing region-wide population declines.

Use of multiple dispersal pathways facilitates amphibian persistence in stream networks.

Science.gov (United States)

Campbell Grant, Evan H; Nichols, James D; Lowe, Winsor H; Fagan, William F

2010-04-13

Although populations of amphibians are declining worldwide, there is no evidence that salamanders occupying small streams are experiencing enigmatic declines, and populations of these species seem stable. Theory predicts that dispersal through multiple pathways can stabilize populations, preventing extinction in habitat networks. However, empirical data to support this prediction are absent for most species, especially those at risk of decline. Our mark-recapture study of stream salamanders reveals both a strong upstream bias in dispersal and a surprisingly high rate of overland dispersal to adjacent headwater streams. This evidence of route-dependent variation in dispersal rates suggests a spatial mechanism for population stability in headwater-stream salamanders. Our results link the movement behavior of stream salamanders to network topology, and they underscore the importance of identifying and protecting critical dispersal pathways when addressing region-wide population declines.

Analysis of a Mathematical Model of Emerging Infectious Disease Leading to Amphibian Decline

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Muhammad Dur-e-Ahmad

2014-01-01

Full Text Available We formulate a three-dimensional deterministic model of amphibian larvae population to investigate the cause of extinction due to the infectious disease. The larvae population of the model is subdivided into two classes, exposed and unexposed, depending on their vulnerability to disease. Reproduction ratio ℛ0 has been calculated and we have shown that if ℛ01, we discussed different scenarios under which an infected population can survive or be eliminated using stability and persistence analysis. Finally, we also used Hopf bifurcation analysis to study the stability of periodic solutions.

The Maryland Amphibian and Reptile Atlas: A Volunteer-Based Distributional Survey

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Heather R. Cunningham

2012-01-01

Full Text Available Declines of amphibian and reptile populations are well documented. Yet a lack of understanding of their distribution may hinder conservation planning for these species. The Maryland Amphibian and Reptile Atlas project (MARA was launched in 2010. This five-year, citizen science project will document the distribution of the 93 amphibian and reptile species in Maryland. During the 2010 and 2011 field seasons, 488 registered MARA volunteers collected 13,919 occurrence records that document 85 of Maryland's amphibian and reptile species, including 19 frog, 20 salamander, five lizard, 25 snake, and 16 turtle species. Thirteen of these species are of conservation concern in Maryland. The MARA will establish a baseline by which future changes in the distribution of populations of native herpetofauna can be assessed as well as provide information for immediate management actions for rare and threatened species. As a citizen science project it has the added benefit of educating citizens about native amphibian and reptile diversity and its ecological benefits—an important step in creating an informed society that actively participates in the long-term conservation of Maryland's nature heritage.

Reproduction, Embryonic Development, and Maternal Transfer of Contaminants in the Amphibian Gastrophryne carolinensis

OpenAIRE

Hopkins, William Alexander; DuRant, Sarah Elizabeth; Staub, Brandon Patrick; Rowe, Christopher Lee; Jackson, Brian Phillip

2005-01-01

Although many amphibian populations around the world are declining at alarming rates, the cause of most declines remains unknown. Environmental contamination is one of several factors implicated in declines and may have particularly important effects on sensitive developmental stages. Despite the severe effects of maternal transfer of contaminants on early development in other vertebrate lineages, no studies have examined the effects of maternal transfer of contaminants on reproduction or dev...

Looking for attitudes related to amphibian species decline: how are peer-reviewed publications of education activities compared to ecological research?

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ROGER P. MORMUL

Full Text Available ABSTRACT Biodiversity decline has been the focus of discussions in the last decade, especially on the amphibian species decline. After a scientometric analysis using international databases, we found that the number of peer-reviewed articles considering education practices related to the theme increased along with the number of ecological researches. However, the increase in ecological researches is much higher than the increase in publications of education practices. Studies suggest that conservation attitudes are important and that education practices are an important tool for improving human perceptions on this subject. In this sense, increase the publication of projects and programs results related to local education practices in international journals could help the dissemination of efficient methods for conservation, as well as facilitating access to information internationally, since species decline, especially for amphibians, is a global concern. Then, we suggest that educational practices, at least when related to conservation, should follow a more standardized protocol, and be published in international journals, as the efficiency of such practices should be evaluated and methods once published could help other nations to improve their ecological literacy.

DNA barcoding applied to ex situ tropical amphibian conservation programme reveals cryptic diversity in captive populations.

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Crawford, Andrew J; Cruz, Catalina; Griffith, Edgardo; Ross, Heidi; Ibáñez, Roberto; Lips, Karen R; Driskell, Amy C; Bermingham, Eldredge; Crump, Paul

2013-11-01

Amphibians constitute a diverse yet still incompletely characterized clade of vertebrates, in which new species are still being discovered and described at a high rate. Amphibians are also increasingly endangered, due in part to disease-driven threats of extinctions. As an emergency response, conservationists have begun ex situ assurance colonies for priority species. The abundance of cryptic amphibian diversity, however, may cause problems for ex situ conservation. In this study we used a DNA barcoding approach to survey mitochondrial DNA (mtDNA) variation in captive populations of 10 species of Neotropical amphibians maintained in an ex situ assurance programme at El Valle Amphibian Conservation Center (EVACC) in the Republic of Panama. We combined these mtDNA sequences with genetic data from presumably conspecific wild populations sampled from across Panama, and applied genetic distance-based and character-based analyses to identify cryptic lineages. We found that three of ten species harboured substantial cryptic genetic diversity within EVACC, and an additional three species harboured cryptic diversity among wild populations, but not in captivity. Ex situ conservation efforts focused on amphibians are therefore vulnerable to an incomplete taxonomy leading to misidentification among cryptic species. DNA barcoding may therefore provide a simple, standardized protocol to identify cryptic diversity readily applicable to any amphibian community. © 2012 John Wiley & Sons Ltd.

Using occupancy models to understand the distribution of an amphibian pathogen, Batrachochytrium dendrobatidis

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Adams, Michael J.; Chelgren, Nathan; Reinitz, David M.; Cole, Rebecca A.; Rachowicz, L.J.; Galvan, Stephanie; Mccreary, Brome; Pearl, Christopher A.; Bailey, Larissa L.; Bettaso, Jamie B.; Bull, Evelyn L.; Leu, Matthias

2010-01-01

Batrachochytrium dendrobatidis is a fungal pathogen that is receiving attention around the world for its role in amphibian declines. Study of its occurrence patterns is hampered by false negatives: the failure to detect the pathogen when it is present. Occupancy models are a useful but currently underutilized tool for analyzing detection data when the probability of detecting a species is population, was related to amphibian development stage, day of the year, elevation, and human activities. Batrachochytrium dendrobatidis was found throughout our study area but was only estimated to occur in 53.4% of 78 populations of native amphibians and 66.4% of 40 populations of nonnative Rana catesbeiana tested. We found little evidence to support any spatial hypotheses concerning the probability that the pathogen occurs in a population, but did find evidence of some taxonomic variation. We discuss the interpretation of occupancy model parameters, when, unlike a conventional occupancy application, the number of potential samples or observations is finite.

Dynamics and genetics of a disease-driven species decline to near extinction: lessons for conservation.

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Hudson, M A; Young, R P; D'Urban Jackson, J; Orozco-terWengel, P; Martin, L; James, A; Sulton, M; Garcia, G; Griffiths, R A; Thomas, R; Magin, C; Bruford, M W; Cunningham, A A

2016-08-03

Amphibian chytridiomycosis has caused precipitous declines in hundreds of species worldwide. By tracking mountain chicken (Leptodactylus fallax) populations before, during and after the emergence of chytridiomycosis, we quantified the real-time species level impacts of this disease. We report a range-wide species decline amongst the fastest ever recorded, with a loss of over 85% of the population in fewer than 18 months on Dominica and near extinction on Montserrat. Genetic diversity declined in the wild, but emergency measures to establish a captive assurance population captured a representative sample of genetic diversity from Montserrat. If the Convention on Biological Diversity's targets are to be met, it is important to evaluate the reasons why they appear consistently unattainable. The emergence of chytridiomycosis in the mountain chicken was predictable, but the decline could not be prevented. There is an urgent need to build mitigation capacity where amphibians are at risk from chytridiomycosis.

Annual Report: 2014: Partners in Amphibian and Reptile Conservation (PARC)

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Weir, Linda A.; Nanjappa, P.; Apodaca, J.J.; Williams, J.

2015-01-01

Partners in Amphibian and Reptile Conservation (PARC) was established in 1999 to address the widespread declines, extinctions, and range reductions of amphibians and reptiles, with a focus on conservation of taxa and habitats in North America. Amphibians and reptiles are affected by a broad range of human activities, both as incidental effects of habitat alteration and direct effects from overexploitation; these animals are also burdened by humans attitudes – that amphibians and reptiles are either dangerous or of little environmental or economic value. However, PARC members understand these taxa are important parts of our natural and cultural heritage and they serve important roles in ecosystems throughout the world. With many amphibians and reptiles classified as threatened with extinction, conservation to ensure healthy populations of these animals has never been more important. As you will see herein, PARC’s 15th anniversary has been marked with major accomplishments and an ever-increasing momentum. With your help, PARC can continue to build on its successes and protect these vital species.

Climate warming and the decline of amphibians and reptiles in Europe

DEFF Research Database (Denmark)

Araújo, Miguel B.; Thuiller, W.; Pearson, R. G.

2006-01-01

deleterious than previously postulated; indeed, climate cooling would be more deleterious for the persistence of amphibian and reptile species than warming. The ability of species to cope with climate warming may, however, be offset by projected decreases in the availability of water. This should......-east are projected to gain suitable climate. This is because dry conditions in the south-west are projected to increase, approaching the levels found in North Africa, where few amphibian species are able to persist. Main conclusions The impact of increasing temperatures on amphibian and reptile species may be less...

Acute toxicity tests and meta-analysis identify gaps in tropical ecotoxicology for amphibians.

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Ghose, Sonia L; Donnelly, Maureen A; Kerby, Jacob; Whitfield, Steven M

2014-09-01

Amphibian populations are declining worldwide, particularly in tropical regions where amphibian diversity is highest. Pollutants, including agricultural pesticides, have been identified as a potential contributor to decline, yet toxicological studies of tropical amphibians are very rare. The present study assesses toxic effects on amphibians of 10 commonly used commercial pesticides in tropical agriculture using 2 approaches. First, the authors conducted 8-d toxicity assays with formulations of each pesticide using individually reared red-eyed tree frog (Agalychnis callidryas) tadpoles. Second, they conducted a review of available data for the lethal concentration to kill 50% of test animals from the US Environmental Protection Agency's ECOTOX database to allow comparison with their findings. Lethal concentration estimates from the assays ranged over several orders of magnitude. The nematicides terbufos and ethoprophos and the fungicide chlorothalonil were very highly toxic, with evident effects within an order of magnitude of environmental concentrations. Acute toxicity assays and meta-analysis show that nematicides and fungicides are generally more toxic than herbicides yet receive far less research attention than less toxic herbicides. Given that the tropics have a high diversity of amphibians, the findings emphasize the need for research into the effects of commonly used pesticides in tropical countries and should help guide future ecotoxicological research in tropical regions. © 2014 SETAC.

Coincident mass extirpation of neotropical amphibians with the emergence of the infectious fungal pathogen Batrachochytrium dendrobatidis.

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Cheng, Tina L; Rovito, Sean M; Wake, David B; Vredenburg, Vance T

2011-06-07

Amphibians highlight the global biodiversity crisis because ∼40% of all amphibian species are currently in decline. Species have disappeared even in protected habitats (e.g., the enigmatic extinction of the golden toad, Bufo periglenes, from Costa Rica). The emergence of a fungal pathogen, Batrachochytrium dendrobatidis (Bd), has been implicated in a number of declines that have occurred in the last decade, but few studies have been able to test retroactively whether Bd emergence was linked to earlier declines and extinctions. We describe a noninvasive PCR sampling technique that detects Bd in formalin-preserved museum specimens. We detected Bd by PCR in 83-90% (n = 38) of samples that were identified as positive by histology. We examined specimens collected before, during, and after major amphibian decline events at established study sites in southern Mexico, Guatemala, and Costa Rica. A pattern of Bd emergence coincident with decline at these localities is revealed-the absence of Bd over multiple years at all localities followed by the concurrent emergence of Bd in various species at each locality during a period of population decline. The geographical and chronological emergence of Bd at these localities also indicates a southbound spread from southern Mexico in the early 1970s to western Guatemala in the 1980s/1990s and to Monteverde, Costa Rica by 1987. We find evidence of a historical "Bd epidemic wave" that began in Mexico and subsequently spread to Central America. We describe a technique that can be used to screen museum specimens from other amphibian decline sites around the world.

Epidemic disease decimates amphibian abundance, species diversity, and evolutionary history in the highlands of central Panama

OpenAIRE

Crawford, Andrew J.; Lips, Karen R.; Bermingham, Eldredge

2010-01-01

Amphibian populations around the world are experiencing unprecedented declines attributed to a chytrid fungal pathogen, Batrachochytrium dendrobatidis. Despite the severity of the crisis, quantitative analyses of the effects of the epidemic on amphibian abundance and diversity have been unavailable as a result of the lack of equivalent data collected before and following disease outbreak. We present a community-level assessment combining long-term field surveys and DNA barcode data describing...

Amphibians Testing Negative for Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans on the Qinghai-Tibetan Plateau, China

Institute of Scientific and Technical Information of China (English)

Supen WANG; Wei ZHU; Liqing FAN; Jiaqi LI; Yiming LI

2017-01-01

A disease caused by the fungi Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal) is responsible for recent worldwide declines and extinctions of amphibian populations.The Qinghai-Tibetan Plateau (QTP) is aglobal biodiversity hotspot,yet little is known about the prevalence of Bd and Bsal in this region.In this study,we collected 336 non-invasive skin swabs from wild amphibians (including an exotic amphibian species) on the QTP.In addition,to assess the historical prevalence of Bd and Bsal on the QTP,we collected 117 non-invasive skin swabs from museum-archived amphibian samples (from 1964-1982) originating from the QTP.Our results showed all samples to be negative for Bd and Bsal.The government should ban the potentially harmful introduction of non-native amphibian species to the QTP and educate the public about the impacts of releasing exotic amphibians from chytrid-infected areas into native environments of the QTP.

Batrachochytrium dendrobatidis prevalence and haplotypes in domestic and imported pet amphibians in Japan.

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Tamukai, Kenichi; Une, Yumi; Tominaga, Atsushi; Suzuki, Kazutaka; Goka, Koichi

2014-05-13

The international trade in amphibians is believed to have increased the spread of Batrachochytrium dendrobatidis (Bd), the fungal pathogen responsible for chytridiomycosis, which has caused a rapid decline in amphibian populations worldwide. We surveyed amphibians imported into Japan and those held in captivity for a long period or bred in Japan to clarify the Bd infection status. Samples were taken from 820 individuals of 109 amphibian species between 2008 and 2011 and were analyzed by a nested-PCR assay. Bd prevalence in imported amphibians was 10.3% (58/561), while it was 6.9% (18/259) in those in private collections and commercially bred amphibians in Japan. We identified the genotypes of this fungus using partial DNA sequences of the internal transcribed spacer (ITS) region. Sequencing of PCR products of all 76 Bd-positive samples revealed 11 haplotypes of the Bd ITS region. Haplotype A (DNA Data Bank of Japan accession number AB435211) was found in 90% (52/58) of imported amphibians. The results show that Bd is currently entering Japan via the international trade in exotic amphibians as pets, suggesting that the trade has indeed played a major role in the spread of Bd.

DISTRIBUTION PATTERNS OF LENTIC-BREEDING AMPHIBIANS IN RELATION OF ULTRAVIOLET RADIATION EXPOSURE IN WESTERN NORTH AMERICA

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An increase in ultraviolet (UV-B) radiation has been posited to be a potential factor in the decline of some amphibian population...Much more work is still needed to determine whether UV-B, either alone or in concert with other factors, is causing widespread population losses in ...

Applied reproductive technologies and genetic resource banking for amphibian conservation.

Science.gov (United States)

Kouba, Andrew J; Vance, Carrie K

2009-01-01

As amphibian populations continue to decline, both government and non-government organisations are establishing captive assurance colonies to secure populations deemed at risk of extinction if left in the wild. For the most part, little is known about the nutritional ecology, reproductive biology or husbandry needs of the animals placed into captive breeding programs. Because of this lack of knowledge, conservation biologists are currently facing the difficult task of maintaining and reproducing these species. Academic and zoo scientists are beginning to examine different technologies for maintaining the genetic diversity of founder populations brought out of the wild before the animals become extinct from rapidly spreading epizootic diseases. One such technology is genetic resource banking and applied reproductive technologies for species that are difficult to reproduce reliably in captivity. Significant advances have been made in the last decade for amphibian assisted reproduction including the use of exogenous hormones for induction of spermiation and ovulation, in vitro fertilisation, short-term cold storage of gametes and long-term cryopreservation of spermatozoa. These scientific breakthroughs for a select few species will no doubt serve as models for future assisted breeding protocols and the increasing number of amphibians requiring conservation intervention. However, the development of specialised assisted breeding protocols that can be applied to many different families of amphibians will likely require species-specific modifications considering their wide range of reproductive modes. The purpose of this review is to summarise the current state of knowledge in the area of assisted reproduction technologies and gene banking for the conservation of amphibians.

Ranking ecological risks of multiple chemical stressors on amphibians.

Science.gov (United States)

Fedorenkova, Anastasia; Vonk, J Arie; Lenders, H J Rob; Creemers, Raymond C M; Breure, Anton M; Hendriks, A Jan

2012-06-01

Populations of amphibians have been declining worldwide since the late 1960s. Despite global concern, no studies have quantitatively assessed the major causes of this decline. In the present study, species sensitivity distributions (SSDs) were developed to analyze the sensitivity of anurans for ammonium, nitrate, heavy metals (cadmium, copper), pesticides (18 compounds), and acidification (pH) based on laboratory toxicity data. Ecological risk (ER) was calculated as the probability that a measured environmental concentration of a particular stressor in habitats where anurans were observed would exceed the toxic effect concentrations derived from the species sensitivity distributions. The assessment of ER was used to rank the stressors according to their potential risk to anurans based on a case study of Dutch freshwater bodies. The derived ERs revealed that threats to populations of anurans decreased in the sequence of pH, copper, diazinon, ammonium, and endosulfan. Other stressors studied were of minor importance. The method of deriving ER by combining field observation data and laboratory data provides insight into potential threats to species in their habitats and can be used to prioritize stressors, which is necessary to achieve effective management in amphibian conservation. Copyright © 2012 SETAC.

Species-specific chitin-binding module 18 expansion in the amphibian pathogen Batrachochytrium dendrobatidis.

Science.gov (United States)

Abramyan, John; Stajich, Jason E

2012-01-01

Batrachochytrium dendrobatidis is the causative agent of chytridiomycosis, which is considered one of the driving forces behind the worldwide decline in populations of amphibians. As a member of the phylum Chytridiomycota, B. dendrobatidis has diverged significantly to emerge as the only pathogen of adult vertebrates. Such shifts in lifestyle are generally accompanied by various degrees of genomic modifications, yet neither its mode of pathogenicity nor any factors associated with it have ever been identified. Presented here is the identification and characterization of a unique expansion of the carbohydrate-binding module family 18 (CBM18), specific to B. dendrobatidis. CBM (chitin-binding module) expansions have been likened to the evolution of pathogenicity in a variety of fungus species, making this expanded group a prime candidate for the identification of potential pathogenicity factors. Furthermore, the CBM18 expansions are confined to three categories of genes, each having been previously implicated in host-pathogen interactions. These correlations highlight this specific domain expansion as a potential key player in the mode of pathogenicity in this unique fungus. The expansion of CBM18 in B. dendrobatidis is exceptional in its size and diversity compared to other pathogenic species of fungi, making this genomic feature unique in an evolutionary context as well as in pathogenicity. Amphibian populations are declining worldwide at an unprecedented rate. Although various factors are thought to contribute to this phenomenon, chytridiomycosis has been identified as one of the leading causes. This deadly fungal disease is cause by Batrachochytrium dendrobatidis, a chytrid fungus species unique in its pathogenicity and, furthermore, its specificity to amphibians. Despite more than two decades of research, the biology of this fungus species and its deadly interaction with amphibians had been notoriously difficult to unravel. Due to the alarming rate of worldwide

Can myxosporean parasites compromise fish and amphibian reproduction?

Science.gov (United States)

Sitjà-Bobadilla, Ariadna

2009-08-22

Research into fish and amphibian reproduction has increased exponentially in recent years owing to the expansion of the aquaculture industry, the need to recover fishery populations, the impact of endocrine disruptors on the aquatic environment and the global decline of amphibian populations. This review focuses on a group of parasites, the Myxozoa, that affect fish and amphibian reproduction. Lists of the myxosporeans that specifically infect gonads are provided. Most of these are parasitic of freshwater hosts, and most amphibian cases are reported from testes. Sex specificity and sex reversal are discussed in relation to gonadal parasitism. The immune response of the fish to the infection is described, and the contribution of the immunoprivilege of gonads to host invasion is emphasized. The pathological effect of these parasites can be significant, especially in aquacultured broodstocks, on some occasions, leading to parasitic castration. Although myxosporean parasites are currently not very frequent in gonads, their impact could increase in the future owing to the transactions in the global market. Their easy release into the aquatic environment with spawning could make their spreading even more feasible. In the absence of commercial drugs or vaccines to treat and prevent these infections, there is an urgent need to develop specific, rapid and reliable diagnostic tools to control and manage animal movements. In addition, much effort is still to be made on deciphering the life cycle of these organisms, their invasion strategies and their immune evasion mechanisms.

Acid precipitation studies in Colorado and Wyoming: interim report of surveys of montane amphibians and water chemistry

Science.gov (United States)

Corn, Paul Stephen; Stolzenburg, William; Bury, R. Bruce

1989-01-01

Acid deposition may be detrimental or stressful to native populations of wildlife. Because many species of amphibians breed in shallow ponds created by spring rains or melting snow, they may be particularly vulnerable to the effects of acidification. From 1986 to 1988, we surveyed 105 locations in the central Rocky Mountains where amphibians had been recorded previously, and we found that two species of amphibians had experiences major losses. We found the northern leopard frog (Rana pipiens) at only 4 of 33 (12%) historically known localities, and the boreal toad (Bufo boreas) was present at 10 of 59 (17%) known localities. Three other species have not suffered region-wide declines. Tiger salamanders (Ambystoma tigrinum) and wood frogs (Rana sylvatica) were present at 45% and 69% of known localities respectively, and were observed at several localities were they had not been recorded previously. Chorus frogs (Pseudacris triseriata) suffered a catastrophic decline in population size in one population monitored since 1961, but regionally, this species was observed in 36 of 56 (64%) known localities and in another 19 localities where there were no previous records. Complete water chemistry was recorded for 41 localities, and pH was measured at 110 sites in total. Acid neutralizing capacity, pH, specific conductivity, and cation concentrations were negatively correlated with elevation. However, in mountain ponds and lakes, pH was rarely less than 6.0 during the amphibian breeding season. We tested the tolerance of embryos of the four species of frogs to low pH. The LC50 pH was 4.8 for chorus frogs, 4.4-4.7 for leopard frogs, 4.4-4.5 for boreal toads, and 4.2-4.3 for wood frogs. Survival of wood frog embryos declined when exposed to aluminum concentrations of 100 µg/L or greater, but boreal toad embryos survived exposure to aluminum concentrations of 400 µg/L. Acid deposition does not appear to be a major factor in the decline of leopard frogs and boreal toads

Who fears and who welcomes population decline?

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Hendrik P. Van Dalen

2011-08-01

Full Text Available European countries are experiencing population decline and the tacit assumption in most analyses is that the decline may have detrimental welfare effects. In this paper we use a survey among the population in the Netherlands to discover whether population decline is always met with fear. A number of results stand out: population size preferences differ by geographic proximity: at a global level the majority of respondents favors a (global population decline, but closer to home one supports a stationary population. Population decline is clearly not always met with fear: 31 percent would like the population to decline at the national level and they generally perceive decline to be accompanied by immaterial welfare gains (improvement environment as well as material welfare losses (tax increases, economic stagnation. In addition to these driving forces it appears that the attitude towards immigrants is a very strong determinant at all geographical levels: immigrants seem to be a stronger fear factor than population decline.

Do effects of mercury in larval amphibians persist after metamorphosis?

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Todd, Brian D; Willson, John D; Bergeron, Christine M; Hopkins, William A

2012-01-01

Despite widespread concern about the role of environmental contaminants in global amphibian declines, and evidence that post-metamorphic life stages contribute disproportionately to amphibian population dynamics, most studies in amphibian ecotoxicology focus on larval life stages. Studies that focus solely on early life stages may miss important effects of contaminant exposure, such as latent effects that manifest some time after previous exposure. Moreover, it is often assumed that effects observed in amphibian larvae will persist to affect survival or reproduction later in life. We used terrestrial enclosures to determine whether exposure to mercury (Hg) through maternal transfer and/or larval diet had any adverse effects in post-metamorphic American toads (Bufo americanus). We found a 5% difference in size at metamorphosis that was attributed to maternal Hg exposure persisted for 1 year in the terrestrial environment, resulting in a 7% difference at the conclusion of the study. Although patterns of survival differed among treatments through time, we found no overall difference in survival after 1 year. We also found no evidence of emergent latent effects in the terrestrial toads that could be attributed to earlier exposure. Our results indicate that adverse effects of maternal Hg exposure that were observed in larval amphibians may persist to affect later terrestrial life stages but that no novel adverse effects developed when animals were raised in a semi-natural environment. Moreover, we found no evidence of persistent effects of dietary Hg exposure in larvae, highlighting a need for greater focus on maternal effects in amphibian ecotoxicology. Finally, we suggest an increase in the use of longitudinal studies to better understand contaminant impacts to amphibian populations via effects in both aquatic and terrestrial life stages.

The hypothalamus-pituitary-thyroid axis in teleosts and amphibians: Endocrine disruption and its consequences to natural populations

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Carr, J.A.; Patino, R.

2011-01-01

Teleosts and pond-breeding amphibians may be exposed to a wide variety of anthropogenic, waterborne contaminants that affect the hypothalamus-pituitary-thyroid (HPT) axis. Because thyroid hormone is required for their normal development and reproduction, the potential impact of HPT-disrupting contaminants on natural teleost and amphibian populations raises special concern. There is laboratory evidence indicating that persistent organic pollutants, heavy metals, pharmaceutical and personal care products, agricultural chemicals, and aerospace products may alter HPT activity, development, and reproduction in teleosts and amphibians. However, at present there is no evidence to clearly link contaminant-induced HPT alterations to impairments in teleost or amphibian population health in the field. Also, with the exception of perchlorate for which laboratory studies have shown a direct link between HPT disruption and adverse impacts on development and reproductive physiology, little is known about if or how other HPT-disrupting contaminants affect organismal performance. Future field studies should focus on establishing temporal associations between the presence of HPT-disrupting chemicals, the occurrence of HPT alterations, and adverse effects on development and reproduction in natural populations; as well as determining how complex mixtures of HPT contaminants affect organismal and population health. ?? 2010 Elsevier Inc.

The hypothalamus–pituitary–thyroid axis in teleosts and amphibians: Endocrine disruption and its consequences to natural populations

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Carr, J.A.; Patino, Reynaldo

2011-01-01

Teleosts and pond-breeding amphibians may be exposed to a wide variety of anthropogenic, waterborne contaminants that affect the hypothalamus-pituitary-thyroid (HPT) axis. Because thyroid hormone is required for their normal development and reproduction, the potential impact of HPT-disrupting contaminants on natural teleost and amphibian populations raises special concern. There is laboratory evidence indicating that persistent organic pollutants, heavy metals, pharmaceutical and personal care products, agricultural chemicals, and aerospace products may alter HPT activity, development, and reproduction in teleosts and amphibians. However, at present there is no evidence to clearly link contaminant-induced HPT alterations to impairments in teleost or amphibian population health in the field. Also, with the exception of perchlorate for which laboratory studies have shown a direct link between HPT disruption and adverse impacts on development and reproductive physiology, little is known about if or how other HPT-disrupting contaminants affect organismal performance. Future field studies should focus on establishing temporal associations between the presence of HPT-disrupting chemicals, the occurrence of HPT alterations, and adverse effects on development and reproduction in natural populations; as well as determining how complex mixtures of HPT contaminants affect organismal and population health.

Presence of the amphibian chytrid fungus Batrachochytrium dendrobatidis in native amphibians exported from Madagascar.

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Jonathan E Kolby

Full Text Available The emerging infectious disease chytridiomycosis is driven by the spread of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd, a highly virulent pathogen threatening global amphibian biodiversity. Although pandemic in distribution, previous intensive field surveys have failed to detect Bd in Madagascar, a biodiversity hotspot home to hundreds of endemic amphibian species. Due to the presence of Bd in nearby continental Africa and the ecological crisis that can be expected following establishment in Madagascar, enhanced surveillance is imperative. I sampled 565 amphibians commercially exported from Madagascar for the presence of Bd upon importation to the USA, both to assist early detection efforts and demonstrate the conservation potential of wildlife trade disease surveillance. Bd was detected in three animals via quantitative PCR: a single Heterixalus alboguttatus, Heterixalus betsileo, and Scaphiophryne spinosa. This is the first time Bd has been confirmed in amphibians from Madagascar and presents an urgent call to action. Our early identification of pathogen presence prior to widespread infection provides the necessary tools and encouragement to catalyze a swift, targeted response to isolate and eradicate Bd from Madagascar. If implemented before establishment occurs, an otherwise likely catastrophic decline in amphibian biodiversity may be prevented.

Presence of the amphibian chytrid fungus Batrachochytrium dendrobatidis in native amphibians exported from Madagascar.

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Kolby, Jonathan E

2014-01-01

The emerging infectious disease chytridiomycosis is driven by the spread of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd), a highly virulent pathogen threatening global amphibian biodiversity. Although pandemic in distribution, previous intensive field surveys have failed to detect Bd in Madagascar, a biodiversity hotspot home to hundreds of endemic amphibian species. Due to the presence of Bd in nearby continental Africa and the ecological crisis that can be expected following establishment in Madagascar, enhanced surveillance is imperative. I sampled 565 amphibians commercially exported from Madagascar for the presence of Bd upon importation to the USA, both to assist early detection efforts and demonstrate the conservation potential of wildlife trade disease surveillance. Bd was detected in three animals via quantitative PCR: a single Heterixalus alboguttatus, Heterixalus betsileo, and Scaphiophryne spinosa. This is the first time Bd has been confirmed in amphibians from Madagascar and presents an urgent call to action. Our early identification of pathogen presence prior to widespread infection provides the necessary tools and encouragement to catalyze a swift, targeted response to isolate and eradicate Bd from Madagascar. If implemented before establishment occurs, an otherwise likely catastrophic decline in amphibian biodiversity may be prevented.

Modeling habitat split: landscape and life history traits determine amphibian extinction thresholds.

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Carlos Roberto Fonseca

Full Text Available Habitat split is a major force behind the worldwide decline of amphibian populations, causing community change in richness and species composition. In fragmented landscapes, natural remnants, the terrestrial habitat of the adults, are frequently separated from streams, the aquatic habitat of the larvae. An important question is how this landscape configuration affects population levels and if it can drive species to extinction locally. Here, we put forward the first theoretical model on habitat split which is particularly concerned on how split distance - the distance between the two required habitats - affects population size and persistence in isolated fragments. Our diffusive model shows that habitat split alone is able to generate extinction thresholds. Fragments occurring between the aquatic habitat and a given critical split distance are expected to hold viable populations, while fragments located farther away are expected to be unoccupied. Species with higher reproductive success and higher diffusion rate of post-metamorphic youngs are expected to have farther critical split distances. Furthermore, the model indicates that negative effects of habitat split are poorly compensated by positive effects of fragment size. The habitat split model improves our understanding about spatially structured populations and has relevant implications for landscape design for conservation. It puts on a firm theoretical basis the relation between habitat split and the decline of amphibian populations.

Modeling habitat split: landscape and life history traits determine amphibian extinction thresholds.

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Fonseca, Carlos Roberto; Coutinho, Renato M; Azevedo, Franciane; Berbert, Juliana M; Corso, Gilberto; Kraenkel, Roberto A

2013-01-01

Habitat split is a major force behind the worldwide decline of amphibian populations, causing community change in richness and species composition. In fragmented landscapes, natural remnants, the terrestrial habitat of the adults, are frequently separated from streams, the aquatic habitat of the larvae. An important question is how this landscape configuration affects population levels and if it can drive species to extinction locally. Here, we put forward the first theoretical model on habitat split which is particularly concerned on how split distance - the distance between the two required habitats - affects population size and persistence in isolated fragments. Our diffusive model shows that habitat split alone is able to generate extinction thresholds. Fragments occurring between the aquatic habitat and a given critical split distance are expected to hold viable populations, while fragments located farther away are expected to be unoccupied. Species with higher reproductive success and higher diffusion rate of post-metamorphic youngs are expected to have farther critical split distances. Furthermore, the model indicates that negative effects of habitat split are poorly compensated by positive effects of fragment size. The habitat split model improves our understanding about spatially structured populations and has relevant implications for landscape design for conservation. It puts on a firm theoretical basis the relation between habitat split and the decline of amphibian populations.

Amphibian Chytrid Fungus in Madagascar neither Shows Widespread Presence nor Signs of Certain Establishment.

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Kolby, Jonathan E; Skerratt, Lee F

2015-01-01

The global spread of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) is associated with amphibian mass mortality, population decline, and extinction. Over the past decade, concern has been expressed for the potential introduction of Bd to Madagascar, a global hotspot of amphibian biodiversity. Following years without detection, widespread Bd presence in Madagascar has now been reported (Bletz et al. 2015a), raising international conservation concern. Before reacting to this finding with a significant management response, the accuracy and context of the data warrant cautious review. Re-examination of a 10-year dataset together with results from more recent surveillance (Kolby et al. 2015) does not yet demonstrate widespread Bd presence. Detection of Bd at "positive" locations in Madagascar has been inconsistent for unknown reasons. Whether Bd is established in Madagascar (i.e. populations are self-sustaining) or instead requires continued introduction to persist also remains uncertain. The deployment of emergency conservation rescue initiatives is expected to target areas where the distribution of Bd and the risk of chytridiomycosis endangering amphibians is believed to overlap. Thus, erroneous description of Bd presence would misdirect limited conservation resources. Standardized surveillance and confirmatory surveys are now imperative to reliably characterize the distribution, potential spread, virulence and overall risk of Bd to amphibians in Madagascar.

Amphibian Chytrid Fungus in Madagascar neither Shows Widespread Presence nor Signs of Certain Establishment.

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Jonathan E Kolby

Full Text Available The global spread of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd is associated with amphibian mass mortality, population decline, and extinction. Over the past decade, concern has been expressed for the potential introduction of Bd to Madagascar, a global hotspot of amphibian biodiversity. Following years without detection, widespread Bd presence in Madagascar has now been reported (Bletz et al. 2015a, raising international conservation concern. Before reacting to this finding with a significant management response, the accuracy and context of the data warrant cautious review. Re-examination of a 10-year dataset together with results from more recent surveillance (Kolby et al. 2015 does not yet demonstrate widespread Bd presence. Detection of Bd at "positive" locations in Madagascar has been inconsistent for unknown reasons. Whether Bd is established in Madagascar (i.e. populations are self-sustaining or instead requires continued introduction to persist also remains uncertain. The deployment of emergency conservation rescue initiatives is expected to target areas where the distribution of Bd and the risk of chytridiomycosis endangering amphibians is believed to overlap. Thus, erroneous description of Bd presence would misdirect limited conservation resources. Standardized surveillance and confirmatory surveys are now imperative to reliably characterize the distribution, potential spread, virulence and overall risk of Bd to amphibians in Madagascar.

DEMOGRAPHY AND SPATIAL POPULATION STRUCTURE IN CALIFORNIA TIGER SALAMANDER

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Although the causes of many amphibian declines remain mysterious, there is general agreement that human habitat alteration represents the greatest threat to amphibian populations. In January 2000 the US Fish and Wildlife Service proposed listing Santa Barbara County California Ti...

Photo-identification in amphibian studies: a test of I3S Pattern

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Marco Sannolo

2016-06-01

Full Text Available Photo-identification is used for individual recognition of several animal species. It gives the possibility to take photos of large species from a distance or to avoid invasive marking techniques in small animals. For amphibians, the use of non-invasive marking methods is even more relevant in the light of their global decline. Here we use the photo-identification data from a population of Triturus carnifex to validate the photo-identification software I3S Pattern. This recently developed utility has never been applied to amphibians. The software proved to be efficient and accurate for individual recognition for this species. Contrarily to the previous releases of the I3S family, I3S Pattern is particularly suitable for amphibians characterized by a complex individual pattern of large blotches or irregular spots, which are not readily identified by eye.

Effect of road deicing salt on the susceptibility of amphibian embryos to infection by water molds.

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Karraker, Nancy E; Ruthig, Gregory R

2009-01-01

Some causative agents of amphibian declines act synergistically to impact individual amphibians and their populations. In particular, pathogenic water molds (aquatic oomycetes) interact with environmental stressors and increase mortality in amphibian embryos. We documented colonization of eggs of three amphibian species, the wood frog (Rana sylvatica), the green frog (Rana clamitans), and the spotted salamander (Ambystoma maculatum), by water molds in the field and examined the interactive effects of road deicing salt and water molds, two known sources of mortality for amphibian embryos, on two species, R. clamitans and A. maculatum in the laboratory. We found that exposure to water molds did not affect embryonic survivorship in either A. maculatum or R. clamitans, regardless of the concentration of road salt to which their eggs were exposed. Road salt decreased survivorship of A. maculatum, but not R. clamitans, and frequency of malformations increased significantly in both species at the highest salinity concentration. The lack of an effect of water molds on survival of embryos and no interaction between road salt and water molds indicates that observations of colonization of these eggs by water molds in the field probably represent a secondary invasion of unfertilized eggs or of embryos that had died of other causes. Given increasing salinization of freshwater habitats on several continents and the global distribution of water molds, our results suggest that some amphibian species may not be susceptible to the combined effects of these factors, permitting amphibian decline researchers to devote their attention to other potential causes.

Amphibian responses to wildfire in the western united states: Emerging patterns from short-term studies

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Hossack, B.R.; Pilliod, D.S.

2011-01-01

The increased frequency and severity of large wildfires in the western United States is an important ecological and management issue with direct relevance to amphibian conservation. Although the knowledge of fire effects on amphibians in the region is still limited relative to most other vertebrate species, we reviewed the current literature to determine if there are evident patterns that might be informative for conservation or management strategies. Of the seven studies that compared pre- and post-wildfire data on a variety of metrics, ranging from amphibian occupancy to body condition, two reported positive responses and five detected negative responses by at least one species. Another seven studies used a retrospective approach to compare effects of wildfire on populations: two studies reported positive effects, three reported negative effects from wildfire, and two reported no effects. All four studies that included plethodontid salamanders reported negative effects on populations or individuals; these effects were greater in forests where fire had been suppressed and in areas that burned with high severity. Species that breed in streams are also vulnerable to post-wildfire changes in habitat, especially in the Southwest. Wildfire is also important for maintaining suitable habitat for diverse amphibian communities, although those results may not be evident immediately after an area burns. We expect that wildfire will extirpate few healthy amphibian populations, but it is still unclear how populations will respond to wildfire in the context of land management (including pre- and post-fire timber harvest) and fragmentation. Wildfire may also increase the risk of decline or extirpation for small, isolated, or stressed (e.g., from drought or disease) populations. Improved understanding of how these effects vary according to changes in fire frequency and severity are critical to form more effective conservation strategies for amphibians in the western United States.

Chytridiomycosis: a global threat to amphibians.

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Pereira, P L L; Torres, A M C; Soares, D F M; Hijosa-Valsero, M; Bécares, E

2013-12-01

Chytridiomycosis, which is caused by Batrachochytrium dendrobatidis, is an emerging infectious disease of amphibians. The disease is one of the main causes of the global decline in amphibians. The aetiological agent is ubiquitous, with worldwide distribution, and affects a large number of amphibian species in several biomes. In the last decade, scientific research has substantially increased knowledge of the aetiological agent and the associated infection. However, important epidemiological aspects of the environment-mediated interactions between the aetiological agent and the host are not yet clear. The objective of the present review is to describe chytridiomycosis with regard to the major features of the aetiological agent, the host and the environment.

Evidence for the persistence of food web structure after amphibian extirpation in a Neotropical stream.

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Barnum, Thomas R; Drake, John M; Colón-Gaud, Checo; Rugenski, Amanda T; Frauendorf, Therese C; Connelly, Scott; Kilham, Susan S; Whiles, Matt R; Lips, Karen R; Pringle, Catherine M

2015-08-01

Species losses are predicted to simplify food web structure, and disease-driven amphibian declines in Central America offer an opportunity to test this prediction. Assessment of insect community composition, combined with gut content analyses, was used to generate periphyton-insect food webs for a Panamanian stream, both pre- and post-amphibian decline. We then used network analysis to assess the effects of amphibian declines on food web structure. Although 48% of consumer taxa, including many insect taxa, were lost between pre- and post-amphibian decline sampling dates, connectance declined by less than 3%. We then quantified the resilience of food web structure by calculating the number of expected cascading extirpations from the loss of tadpoles. This analysis showed the expected effects of species loss on connectance and linkage density to be more than 60% and 40%, respectively, than were actually observed. Instead, new trophic linkages in the post-decline food web reorganized the food web topology, changing the identity of "hub" taxa, and consequently reducing the effects of amphibian declines on many food web attributes. Resilience of food web attributes was driven by a combination of changes in consumer diets, particularly those of insect predators, as well as the appearance of generalist insect consumers, suggesting that food web structure is maintained by factors independent of the original trophic linkages.

Invasive reptiles and amphibians.

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Moutou, F; Pastoret, P P

2010-08-01

Although they are frequently lumped together, reptiles and amphibians belong to two very different zoological groups. Nevertheless, one fact is clear: while numerous reptile and amphibian species on Earth are in decline, others have taken advantage of trade or human movements to become established in new lands, adopting different, and sometimes unusual, strategies. The authors have taken a few examples from these two zoological groups that illustrate the majority of cases. A brief analysis of the causes and effects of their introductions into new areas reveals connections with economic interests, trade in companion animals, medical research and public health.

Field evidence for leech-borne transmission of amphibian Ichthyophonus sp.

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Raffel, Thomas R; Dillard, James R; Hudson, Peter J

2006-12-01

Parasites have been implicated in mass mortality events and population declines of amphibians around the world. One pathogen associated with mortality events in North America is an Ichthyophonus sp.-like organism that affects red-spotted newts (Notophthalmus viridescens) and several frog species, yet little is known about the distribution of this pathogen in wild populations or the mechanism of transmission. In an effort to identify factors influencing the distribution and abundance of this pathogen, we measured Ichthyophonus sp. prevalence and a series of factors that could contribute to transmission in 16 newt populations during spring 2004. In contrast to our initial hypotheses of trophic transmission, several lines of evidence suggested a role for the amphibian leech (Placobdella picta) in Ichthyophonus sp. transmission. We propose the mechanistic hypothesis that a leech acquires Ichthyophonus sp. infection when inserting its proboscis into the muscles beneath the skin of infected newts and transmits the infection to other newts in subsequent feeding bouts. We also found effects of host sex, body mass, and breeding condition on Ichthyophonus sp. prevalence and the number of attached leeches. The number of leeches attached to newts was strongly related to the proportion of newt habitat containing emergent vegetation, suggesting that anthropogenic eutrophication might lead to more frequent or severe outbreaks of Ichthyophonus sp. infection in amphibians.

Monitoring strategy for eight amphibian species in French Guiana, South America.

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Elodie A Courtois

Full Text Available Although dramatic amphibian declines have been documented worldwide, only few of such events have been quantitatively documented for the tropical forests of South America. This is due partly to the fact that tropical amphibians are patchily distributed and difficult to detect. We tested three methods often used to monitor population trends in amphibian species in a remote lowland tropical forest of French Guiana. These methods are capture-mark-recapture (CMR, estimation of the number of calling males with repeated counts data and distance sampling, and rates of occupancy inferred by presence/absence data. We monitored eight diurnal, terrestrial amphibian species including five Dendrobatidae and three Bufonidae. We found that CMR, the most precise way of estimating population size, can be used only with two species in high density patches where the recapture rate is high enough. Only for one of the species (Dendrobates tinctorius, a low coefficient of variation (CV = 0.19 can be achieved with 15 to 20 capture events. For dendrobatid species with day-calling males, audio surveys yield a better probability of detection with only 8 audio surveys needed; quantitative estimates can be achieved by computing the number of calling males inferred from audio counts or distance sampling analysis. We therefore suggest that an efficient monitoring protocol for Neotropical amphibian species should include a combination of sighting and audio techniques, and we discuss the need of implementing a large-scale monitoring in order to provide a baseline for comparison with future changes.

Using occupancy models to understand the distribution of an amphibian pathogen, Batrachochytrium dendrobatidis

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Adams, Michael J.; Chelgren, Nathan; Reinitz, David M.; Cole, Rebecca A.; Rachowicz, L.J.; Galvan, Stephanie; Mccreary, Brome; Pearl, Christopher A.; Bailey, Larissa L.; Bettaso, Jamie B.; Bull, Evelyn L.; Leu, Matthias

2010-01-01

Batrachochytrium dendrobatidis is a fungal pathogen that is receiving attention around the world for its role in amphibian declines. Study of its occurrence patterns is hampered by false negatives: the failure to detect the pathogen when it is present. Occupancy models are a useful but currently underutilized tool for analyzing detection data when the probability of detecting a species is <1. We use occupancy models to evaluate hypotheses concerning the occurrence and prevalence of B. dendrobatidis and discuss how this application differs from a conventional occupancy approach. We found that the probability of detecting the pathogen, conditional on presence of the pathogen in the anuran population, was related to amphibian development stage, day of the year, elevation, and human activities. Batrachochytrium dendrobatidis was found throughout our study area but was only estimated to occur in 53.4% of 78 populations of native amphibians and 66.4% of 40 populations of nonnative Rana catesbeiana tested. We found little evidence to support any spatial hypotheses concerning the probability that the pathogen occurs in a population, but did find evidence of some taxonomic variation. We discuss the interpretation of occupancy model parameters, when, unlike a conventional occupancy application, the number of potential samples or observations is finite.

Estrogens can disrupt amphibian mating behavior.

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Frauke Hoffmann

Full Text Available The main component of classical contraceptives, 17α-ethinylestradiol (EE2, has high estrogenic activity even at environmentally relevant concentrations. Although estrogenic endocrine disrupting compounds are assumed to contribute to the worldwide decline of amphibian populations by adverse effects on sexual differentiation, evidence for EE2 affecting amphibian mating behaviour is lacking. In this study, we demonstrate that EE2 exposure at five different concentrations (0.296 ng/L, 2.96 ng/L, 29.64 ng/L, 2.96 µg/L and 296.4 µg/L can disrupt the mating behavior of adult male Xenopus laevis. EE2 exposure at all concentrations lowered male sexual arousal, indicated by decreased proportions of advertisement calls and increased proportions of the call type rasping, which characterizes a sexually unaroused state of a male. Additionally, EE2 at all tested concentrations affected temporal and spectral parameters of the advertisement calls, respectively. The classical and highly sensitive biomarker vitellogenin, on the other hand, was only induced at concentrations equal or higher than 2.96 µg/L. If kept under control conditions after a 96 h EE2 exposure (2.96 µg/L, alterations of male advertisement calls vanish gradually within 6 weeks and result in a lower sexual attractiveness of EE2 exposed males toward females as demonstrated by female choice experiments. These findings indicate that exposure to environmentally relevant EE2 concentrations can directly disrupt male mate calling behavior of X. laevis and can indirectly affect the mating behavior of females. The results suggest the possibility that EE2 exposure could reduce the reproductive success of EE2 exposed animals and these effects might contribute to the global problem of amphibian decline.

A Place to Call Home: Amphibian Use of Created and Restored Wetlands

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Brown, Donald J.; Street, Garrett M.; Nairn, Robert W.; Forstner, Michael R. J.

2012-01-01

Loss and degradation of wetland habitats are major contributing factors to the global decline of amphibians. Creation and restoration of wetlands could be a valuable tool for increasing local amphibian species richness and abundance. We synthesized the peer-reviewed literature addressing amphibian use of created and restored wetlands, focusing on aquatic habitat, upland habitat, and wetland connectivity and configuration. Amphibian species richness or abundance at created and restored wetland...

Interventions for reducing extinction risk in chytridiomycosis-threatened amphibians.

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Scheele, Ben C; Hunter, David A; Grogan, Laura F; Berger, Lee; Kolby, Jon E; McFadden, Michael S; Marantelli, Gerry; Skerratt, Lee F; Driscoll, Don A

2014-10-01

Wildlife diseases pose an increasing threat to biodiversity and are a major management challenge. A striking example of this threat is the emergence of chytridiomycosis. Despite diagnosis of chytridiomycosis as an important driver of global amphibian declines 15 years ago, researchers have yet to devise effective large-scale management responses other than biosecurity measures to mitigate disease spread and the establishment of disease-free captive assurance colonies prior to or during disease outbreaks. We examined the development of management actions that can be implemented after an epidemic in surviving populations. We developed a conceptual framework with clear interventions to guide experimental management and applied research so that further extinctions of amphibian species threatened by chytridiomycosis might be prevented. Within our framework, there are 2 management approaches: reducing Batrachochytrium dendrobatidis (the fungus that causes chytridiomycosis) in the environment or on amphibians and increasing the capacity of populations to persist despite increased mortality from disease. The latter approach emphasizes that mitigation does not necessarily need to focus on reducing disease-associated mortality. We propose promising management actions that can be implemented and tested based on current knowledge and that include habitat manipulation, antifungal treatments, animal translocation, bioaugmentation, head starting, and selection for resistance. Case studies where these strategies are being implemented will demonstrate their potential to save critically endangered species. © 2014 Society for Conservation Biology.

Low levels of chemical anthropogenic pollution may threaten amphibians by impairing predator recognition.

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Polo-Cavia, Nuria; Burraco, Pablo; Gomez-Mestre, Ivan

2016-03-01

Recent studies suggest that direct mortality and physiological effects caused by pollutants are major contributing factors to global amphibian decline. However, even sublethal concentrations of pollutants could be harmful if they combined with other factors to cause high mortality in amphibians. Here we show that sublethal concentrations of pollutants can disrupt the ability of amphibian larvae to recognize predators, hence increasing their risk of predation. This effect is indeed much more important since very low amounts of pollutants are ubiquitous, and environmental efforts are mostly directed towards preventing lethal spills. We analyzed the effects of two common contaminants (humic acid and ammonium nitrate) on the ability of tadpoles of the western spadefoot toad (Pelobates cultripes) to recognize chemical cues from a common predator, nymphs of the dragonfly Anax imperator. We compared the swimming activity of tadpoles in the presence and absence of water-borne chemical cues from dragonflies at different concentrations of humic acid and ammonium nitrate. Tadpoles reduced swimming activity in response to predator cues in the absence of pollutants, whereas they remained unresponsive to these cues when either humic acid or ammonium nitrate was added to the water, even at low concentrations. Moreover, changes in tadpole activity associated with the pollutants themselves were non-significant, indicating no toxic effect. Alteration of the natural chemical environment of aquatic systems by pollutants may be an important contributing cause for declines in amphibian populations, even at sublethal concentrations. Copyright © 2016 Elsevier B.V. All rights reserved.

Partners in amphibian and reptile conservation 2013 annual report

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Conrad, Paulette M.; Weir, Linda A.; Nanjappa, Priya

2014-01-01

Partners in Amphibian and Reptile Conservation (PARC) was established in 1999 to address the widespread declines, extinctions, and range reductions of amphibians and reptiles, with a focus on conservation of taxa and habitats in North America. Amphibians and reptiles are affected by a broad range of human activities, both as incidental effects of habitat alteration and direct effect from overexploitation; these animals are also challenged by the perception that amphibians and reptiles are either dangerous or of little environmental or economic value. However, PARC members understand these taxa are important parts of our natural an cultural heritage and they serve important roles in ecosystems throughout the world. With many amphibians and reptiles classified as threatened with extinction, conservation of these animals has never been more important.

Reproduction, embryonic development, and maternal transfer of contaminants in the amphibian Gastrophryne carolinensis.

Science.gov (United States)

Hopkins, William Alexander; DuRant, Sarah Elizabeth; Staub, Brandon Patrick; Rowe, Christopher Lee; Jackson, Brian Phillip

2006-05-01

Although many amphibian populations around the world are declining at alarming rates, the cause of most declines remains unknown. Environmental contamination is one of several factors implicated in declines and may have particularly important effects on sensitive developmental stages. Despite the severe effects of maternal transfer of contaminants on early development in other vertebrate lineages, no studies have examined the effects of maternal transfer of contaminants on reproduction or development in amphibians. We examined maternal transfer of contaminants in eastern narrow-mouth toads (Gastrophryne carolinensis) collected from a reference site and near a coal-burning power plant. Adult toads inhabiting the industrial area transferred significant quantities of selenium and strontium to their eggs, but Se concentrations were most notable (up to 100 microg/g dry mass). Compared with the reference site, hatching success was reduced by 11% in clutches from the contaminated site. In surviving larvae, the frequency of developmental abnormalities and abnormal swimming was 55-58% higher in the contaminated site relative to the reference site. Craniofacial abnormalities were nearly an order of magnitude more prevalent in hatchlings from the contaminated site. When all developmental criteria were considered collectively, offspring from the contaminated site experienced 19% lower viability. Although there was no statistical relationship between the concentration of Se or Sr transferred to eggs and any measure of offspring viability, our study demonstrates that maternal transfer may be an important route of contaminant exposure in amphibians that has been overlooked.

Drought, deluge and declines: the impact of precipitation extremes on amphibians in a changing climate

Science.gov (United States)

Walls, Susan C.; Barichivich, William J.; Brown, Mary E.

2013-01-01

The Class Amphibia is one of the most severely impacted taxa in an on-going global biodiversity crisis. Because amphibian reproduction is tightly associated with the presence of water, climatic changes that affect water availability pose a particularly menacing threat to both aquatic and terrestrial-breeding amphibians. We explore the impacts that one facet of climate change—that of extreme variation in precipitation—may have on amphibians. This variation is manifested principally as increases in the incidence and severity of both drought and major storm events. We stress the need to consider not only total precipitation amounts but also the pattern and timing of rainfall events. Such rainfall “pulses” are likely to become increasingly more influential on amphibians, especially in relation to seasonal reproduction. Changes in reproductive phenology can strongly influence the outcome of competitive and predatory interactions, thus potentially altering community dynamics in assemblages of co-existing species. We present a conceptual model to illustrate possible landscape and metapopulation consequences of alternative climate change scenarios for pond-breeding amphibians, using the Mole Salamander, Ambystoma talpoideum, as an example. Although amphibians have evolved a variety of life history strategies that enable them to cope with environmental uncertainty, it is unclear whether adaptations can keep pace with the escalating rate of climate change. Climate change, especially in combination with other stressors, is a daunting challenge for the persistence of amphibians and, thus, the conservation of global biodiversity.

Selecting for extinction: nonrandom disease-associated extinction homogenizes amphibian biotas.

Science.gov (United States)

Smith, Kevin G; Lips, Karen R; Chase, Jonathan M

2009-10-01

Studying the patterns in which local extinctions occur is critical to understanding how extinctions affect biodiversity at local, regional and global spatial scales. To understand the importance of patterns of extinction at a regional spatial scale, we use data from extirpations associated with a widespread pathogenic agent of amphibian decline, Batrachochytrium dendrobatidis (Bd) as a model system. We apply novel null model analyses to these data to determine whether recent extirpations associated with Bd have resulted in selective extinction and homogenization of diverse tropical American amphibian biotas. We find that Bd-associated extinctions in this region were nonrandom and disproportionately, but not exclusively, affected low-occupancy and endemic species, resulting in homogenization of the remnant amphibian fauna. The pattern of extirpations also resulted in phylogenetic homogenization at the family level and ecological homogenization of reproductive mode and habitat association. Additionally, many more species were extirpated from the region than would be expected if extirpations occurred randomly. Our results indicate that amphibian declines in this region are an extinction filter, reducing regional amphibian biodiversity to highly similar relict assemblages and ultimately causing amplified biodiversity loss at regional and global scales.

Predatory leeches (Hirudinida) may contribute to amphibian declines in the Lassen, California.

Science.gov (United States)

Stead Jonathan; Karen Pope

2010-01-01

Researchers have documented precipitous declines in Cascades Frog (Rana cascadae) populations in the southern portion of the species' range, in the Lassen region of California. Reasons for the declines, however, have not been elucidated. In addition to common, widespread causes, an understanding of local community interactions may be necessary...

Anthropogenic and ecological drivers of amphibian disease (ranavirosis.

Directory of Open Access Journals (Sweden)

Alexandra C North

Full Text Available Ranaviruses are causing mass amphibian die-offs in North America, Europe and Asia, and have been implicated in the decline of common frog (Rana temporaria populations in the UK. Despite this, we have very little understanding of the environmental drivers of disease occurrence and prevalence. Using a long term (1992-2000 dataset of public reports of amphibian mortalities, we assess a set of potential predictors of the occurrence and prevalence of Ranavirus-consistent common frog mortality events in Britain. We reveal the influence of biotic and abiotic drivers of this disease, with many of these abiotic characteristics being anthropogenic. Whilst controlling for the geographic distribution of mortality events, disease prevalence increases with increasing frog population density, presence of fish and wild newts, increasing pond depth and the use of garden chemicals. The presence of an alternative host reduces prevalence, potentially indicating a dilution effect. Ranavirosis occurrence is associated with the presence of toads, an urban setting and the use of fish care products, providing insight into the causes of emergence of disease. Links between occurrence, prevalence, pond characteristics and garden management practices provides useful management implications for reducing the impacts of Ranavirus in the wild.

NIDI scenario. Strong population decline in China

OpenAIRE

de Beer, J.A.A.

2016-01-01

United Nations projections assume that by the end of this century one third of the world population will live in India, China or Nigeria. While population growth in India will slow down and the population size of China will decline, population growth in Nigeria will accelerate. A new NIDI scenario projects less population growth in Nigeria and sharp population decline in China.

Improving the design of amphibian surveys using soil data: A case study in two wilderness areas

Science.gov (United States)

Bowen, K.D.; Beever, E.A.; Gafvert, U.B.

2009-01-01

Amphibian populations are known, or thought to be, declining worldwide. Although protected natural areas may act as reservoirs of biological integrity and serve as benchmarks for comparison with unprotected areas, they are not immune from population declines and extinctions and should be monitored. Unfortunately, identifying survey sites and performing long-term fieldwork within such (often remote) areas involves a special set of problems. We used the USDA Natural Resource Conservation Service Soil Survey Geographic (SSURGO) Database to identify, a priori, potential habitat for aquatic-breeding amphibians on North and South Manitou Islands, Sleeping Bear Dunes National Lakeshore, Michigan, and compared the results to those obtained using National Wetland Inventory (NWI) data. The SSURGO approach identified more target sites for surveys than the NWI approach, and it identified more small and ephemeral wetlands. Field surveys used a combination of daytime call surveys, night-time call surveys, and perimeter surveys. We found that sites that would not have been identified with NWI data often contained amphibians and, in one case, contained wetland-breeding species that would not have been found using NWI data. Our technique allows for easy a priori identification of numerous survey sites that might not be identified using other sources of spatial information. We recognize, however, that the most effective site identification and survey techniques will likely use a combination of methods in addition to those described here.

Hydrologic variability governs population dynamics of a vulnerable amphibian in an arid environment.

Directory of Open Access Journals (Sweden)

Erin R Zylstra

Full Text Available Dynamics of many amphibian populations are governed by the distribution and availability of water. Therefore, understanding the hydrological mechanisms that explain spatial and temporal variation in occupancy and abundance will improve our ability to conserve and recover populations of vulnerable amphibians. We used 16 years of survey data from intermittent mountain streams in the Sonoran Desert to evaluate how availability of surface water affected survival and adult recruitment of a threatened amphibian, the lowland leopard frog (Lithobates yavapaiensis. Across the entire study period, monthly survival of adults ranged from 0.72 to 0.99 during summer and 0.59 to 0.94 during winter and increased with availability of surface water (Z = 7.66; P < 0.01. Recruitment of frogs into the adult age class occurred primarily during winter and ranged from 1.9 to 3.8 individuals/season/pool; like survival, recruitment increased with availability of surface water (Z = 3.67; P < 0.01. Although abundance of frogs varied across seasons and years, we found no evidence of a systematic trend during the 16-year study period. Given the strong influence of surface water on population dynamics of leopard frogs, conservation of many riparian obligates in this and similar arid regions likely depends critically on minimizing threats to structures and ecosystem processes that maintain surface waters. Understanding the influence of surface-water availability on riparian organisms is particularly important because climate change is likely to decrease precipitation and increase ambient temperatures in desert riparian systems, both of which have the potential to alter fundamentally the hydrology of these systems.

Climate Variability, Dissolved Organic Carbon, UV Exposure, and Amphibian Decline

Science.gov (United States)

Brooks, P. D.; O'Reilly, C. M.; Diamond, S.; Corn, S.; Muths, E.; Tonnessen, K.; Campbell, D. H.

2001-12-01

Increasing levels of UV radiation represent a potential threat to aquatic organisms in a wide range of environments, yet controls on in situ variability on UV exposure are relatively unknown. The primary control on the penetration of UV radiation in surface water environments is the amount of photoreactive dissolved organic carbon (DOC). Consequently, biogeochemical processes that control the cycling of DOC also affect the exposure of aquatic organisms to UV radiation. Three years of monitoring UV extinction and DOC composition in Rocky Mountain, Glacier, Sequoia/ Kings Canyon, and Olympic National Parks demonstrate that the amount of fulvic acid DOC is much more important than the total DOC pool in controlling UV attenuation. This photoreactive component of DOC originates primarily in soil, and is subject both to biogeochemical controls (e.g. temperature, moisture, vegetation, soil type) on production, and hydrologic controls on transport to surface water and consequently UV exposure to aquatic organisms. Both of these controls are positively related to precipitation with greater production and transport associated with higher precipitation amounts. For example, an approximately 20 percent reduction in precipitation from 1999 to 2000 resulted in a 27% - 59% reduction in the amount of photoreactive DOC at three sites in Rocky Mountain National Park. These differences in the amount of hydrophobic DOC result in an increase in UV exposure in the aquatic environment by a factor of 2 or more. Implications of these findings for observed patterns of amphibian decline will be discussed.

Amphibian chytridiomycosis: a review with focus on fungus-host interactions.

Science.gov (United States)

Van Rooij, Pascale; Martel, An; Haesebrouck, Freddy; Pasmans, Frank

2015-11-25

Amphibian declines and extinctions are emblematic for the current sixth mass extinction event. Infectious drivers of these declines include the recently emerged fungal pathogens Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans (Chytridiomycota). The skin disease caused by these fungi is named chytridiomycosis and affects the vital function of amphibian skin. Not all amphibians respond equally to infection and host responses might range from resistant, over tolerant to susceptible. The clinical outcome of infection is highly dependent on the amphibian host, the fungal virulence and environmental determinants. B. dendrobatidis infects the skin of a large range of anurans, urodeles and caecilians, whereas to date the host range of B. salamandrivorans seems limited to urodeles. So far, the epidemic of B. dendrobatidis is mainly limited to Australian, neotropical, South European and West American amphibians, while for B. salamandrivorans it is limited to European salamanders. Other striking differences between both fungi include gross pathology and thermal preferences. With this review we aim to provide the reader with a state-of-the art of host-pathogen interactions for both fungi, in which new data pertaining to the interaction of B. dendrobatidis and B. salamandrivorans with the host's skin are integrated. Furthermore, we pinpoint areas in which more detailed studies are necessary or which have not received the attention they merit.

Amphibian recovery after a decrease in acidic precipitation.

Science.gov (United States)

Dolmen, Dag; Finstad, Anders Gravbrøt; Skei, Jon Kristian

2018-04-01

We here report the first sign of amphibian recovery after a strong decline due to acidic precipitation over many decades and peaking around 1980-90. In 2010, the pH level of ponds and small lakes in two heavily acidified areas in southwestern Scandinavia (Aust-Agder and Østfold in Norway) had risen significantly at an (arithmetic) average of 0.14 since 1988-89. Parallel with the general rise in pH, amphibians (Rana temporaria, R. arvalis, Bufo bufo, Lissotriton vulgaris, and Triturus cristatus) had become significantly more common: the frequency of amphibian localities rose from 33% to 49% (n = 115), and the average number of amphibian species per locality had risen from 0.51 to 0.88. In two other (reference) areas, one with better buffering capacity (Telemark, n = 21) and the other with much less input of acidic precipitation (Nord-Trøndelag, n = 106), there were no significant changes in pH or amphibians.

Effectiveness of amphibians as biodiversity surrogates in pond conservation.

Science.gov (United States)

Ilg, Christiane; Oertli, Beat

2017-04-01

Amphibian decline has led to worldwide conservation efforts, including the identification and designation of sites for their protection. These sites could also play an important role in the conservation of other freshwater taxa. In 89 ponds in Switzerland, we assessed the effectiveness of amphibians as a surrogate for 4 taxonomic groups that occur in the same freshwater ecosystems as amphibians: dragonflies, aquatic beetles, aquatic gastropods, and aquatic plants. The ponds were all of high value for amphibian conservation. Cross-taxon correlations were tested for species richness and conservation value, and Mantel tests were used to investigate community congruence. Species richness, conservation value, and community composition of amphibians were weakly congruent with these measures for the other taxonomic groups. Paired comparisons for the 5 groups considered showed that for each metric, amphibians had the lowest degree of congruence. Our results imply that site designation for amphibian conservation will not necessarily provide protection for freshwater biodiversity as a whole. To provide adequate protection for freshwater species, we recommend other taxonomic groups be considered in addition to amphibians in the prioritization and site designation process. © 2016 Society for Conservation Biology.

[Economic growth with zero population growth and with declining population].

Science.gov (United States)

Kurz, R

1982-05-01

The effects of both zero population growth and a declining population on economic growth are considered. Although the neoclassical theory of economic growth leads to optimistic results in such cases, the author suggests that this theory cannot be used as a basis for political action. The need for further research into the economic effects of a stationary or declining population is stressed. (summary in ENG)

Occurrence of the amphibian pathogen Batrachochytrium dendrobatidis in the Pacific Northwest.

Science.gov (United States)

C.A. Pearl; E.L. Bull; D.E. Green; J. Bowerman; M.J. Adams; A. Hyatt; W.H. Wente

2007-01-01

Chytridiomycosis (infection by the fungus Batrachochytrium dendrobatidis) is an emerging pathogen of amphibians that is associated with declines in at least four continents. We report results of disease screens from 271 field-sampled amphibians from Oregon and Washington. Chytridiomycosis was detected on 5 of 7 species and from 31 percent of all...

Comment on "Habitat split and the global decline of amphibians".

Science.gov (United States)

Cannatella, David C

2008-05-16

Becker et al. (Reports, 14 December 2007, p. 1775) reported that forest amphibians with terrestrial development are less susceptible to the effects of habitat degradation than those with aquatic larvae. However, analysis with more appropriate statistical methods suggests there is no evidence for a difference between aquatic-reproducing and terrestrial-reproducing species.

Reproduction, embryonic development, and maternal transfer of contaminants in the amphibian Gastrophryne carolinensis

Energy Technology Data Exchange (ETDEWEB)

Hopkins, W.A.; DuRant, S.E.; Staub, B.P.; Rowe, C.L.; Jackson, B.P. [Virginia Polytechnic Institute & State University, Blacksburg, VA (United States). Dept. of Fisheries & Wildlife Science

2006-05-15

Although many amphibian populations around the world are declining at alarming rates, the cause of most declines remains unknown. Environmental contamination is one of several factors implicated in declines and may have particularly important effects on sensitive developmental stages. We examined maternal transfer of contaminants in eastern narrow-mouth toads (Gastrophryne carolinensis) collected from a reference site and near a coal-burning power plant. Adult toads inhabiting the industrial area transferred significant quantities of selenium and strontium to their eggs, but Se concentrations were most notable (up to 100 {mu} g/g dry mass). Compared with the reference site, hatching success was reduced by 11% in clutches from the contaminated site. In surviving larvae, the frequency of developmental abnormalities and abnormal swimming was 55-58% higher in the contaminated site relative to the reference site. Craniofacial abnormalities were nearly an order of magnitude more prevalent in hatchlings from the contaminated site. When all developmental criteria were considered collectively, offspring from the contaminated site experienced 19% lower viability. Although there was no statistical relationship between the concentration of Se or Sr transferred to eggs and any measure of offspring viability, our study demonstrates that maternal transfer may be an important route of contaminant exposure in amphibians that has been overlooked.

Seasonal differences in extinction and colonization drive occupancy dynamics of an imperilled amphibian.

Directory of Open Access Journals (Sweden)

Lea A Randall

Full Text Available A detailed understanding of the population dynamics of many amphibian species is lacking despite concerns about declining amphibian biodiversity and abundance. This paper explores temporal patterns of occupancy and underlying extinction and colonization dynamics in a regionally imperiled amphibian species, the Northern leopard frog (Lithobates pipiens in Alberta. Our study contributes to elucidating regional occupancy dynamics at northern latitudes, where climate extremes likely have a profound effect on seasonal occupancy. The primary advantage of our study is its wide geographic scale (60,000 km2 and the use of repeat visual surveys each spring and summer from 2009-2013. We find that occupancy varied more dramatically between seasons than years, with low spring and higher summer occupancy. Between spring and summer, colonization was high and extinction low; inversely, colonization was low and extinction high over the winter. The dynamics of extinction and colonization are complex, making conservation management challenging. Our results reveal that Northern leopard frog occupancy was constant over the last five years and thus there is no evidence of decline or recovery within our study area. Changes to equilibrium occupancy are most sensitive to increasing colonization in the spring or declining extinction in the summer. Therefore, conservation and management efforts should target actions that are likely to increase spring colonization; this could be achieved through translocations or improving the quality or access to breeding habitat. Because summer occupancy is already high, it may be difficult to improve further. Nevertheless, summer extinction could be reduced by predator control, increasing water quality or hydroperiod of wetlands, or increasing the quality or quantity of summer habitat.

Seasonal differences in extinction and colonization drive occupancy dynamics of an imperilled amphibian.

Science.gov (United States)

Randall, Lea A; Smith, Des H V; Jones, Breana L; Prescott, David R C; Moehrenschlager, Axel

2015-01-01

A detailed understanding of the population dynamics of many amphibian species is lacking despite concerns about declining amphibian biodiversity and abundance. This paper explores temporal patterns of occupancy and underlying extinction and colonization dynamics in a regionally imperiled amphibian species, the Northern leopard frog (Lithobates pipiens) in Alberta. Our study contributes to elucidating regional occupancy dynamics at northern latitudes, where climate extremes likely have a profound effect on seasonal occupancy. The primary advantage of our study is its wide geographic scale (60,000 km2) and the use of repeat visual surveys each spring and summer from 2009-2013. We find that occupancy varied more dramatically between seasons than years, with low spring and higher summer occupancy. Between spring and summer, colonization was high and extinction low; inversely, colonization was low and extinction high over the winter. The dynamics of extinction and colonization are complex, making conservation management challenging. Our results reveal that Northern leopard frog occupancy was constant over the last five years and thus there is no evidence of decline or recovery within our study area. Changes to equilibrium occupancy are most sensitive to increasing colonization in the spring or declining extinction in the summer. Therefore, conservation and management efforts should target actions that are likely to increase spring colonization; this could be achieved through translocations or improving the quality or access to breeding habitat. Because summer occupancy is already high, it may be difficult to improve further. Nevertheless, summer extinction could be reduced by predator control, increasing water quality or hydroperiod of wetlands, or increasing the quality or quantity of summer habitat.

Trends in Rocky Mountain amphibians and the role of beaver as a keystone species

Science.gov (United States)

Hossack, Blake R.; Gould, William R.; Patla, Debra A.; Muths, Erin L.; Daley, Rob; Legg, Kristin; Corn, P. Stephen

2015-01-01

Despite prevalent awareness of global amphibian declines, there is still little information on trends for many widespread species. To inform land managers of trends on protected landscapes and identify potential conservation strategies, we collected occurrence data for five wetland-breeding amphibian species in four national parks in the U.S. Rocky Mountains during 2002–2011. We used explicit dynamics models to estimate variation in annual occupancy, extinction, and colonization of wetlands according to summer drought and several biophysical characteristics (e.g., wetland size, elevation), including the influence of North American beaver (Castor canadensis). We found more declines in occupancy than increases, especially in Yellowstone and Grand Teton national parks (NP), where three of four species declined since 2002. However, most species in Rocky Mountain NP were too rare to include in our analysis, which likely reflects significant historical declines. Although beaver were uncommon, their creation or modification of wetlands was associated with higher colonization rates for 4 of 5 amphibian species, producing a 34% increase in occupancy in beaver-influenced wetlands compared to wetlands without beaver influence. Also, colonization rates and occupancy of boreal toads (Anaxyrus boreas) and Columbia spotted frogs (Rana luteiventris) were ⩾2 times higher in beaver-influenced wetlands. These strong relationships suggest management for beaver that fosters amphibian recovery could counter declines in some areas. Our data reinforce reports of widespread declines of formerly and currently common species, even in areas assumed to be protected from most forms of human disturbance, and demonstrate the close ecological association between beaver and wetland-dependent species.

Death in the clouds: ranavirus associated mortality in assemblage of cloud forest amphibians in Nicaragua

NARCIS (Netherlands)

Stark, T.; Laurijssens, C.; Weterings, M.J.A.; Spitzen-van der Sluis, A.; Martel, A.; Pasmans, F.

2014-01-01

Amphibian diseases are acknowledged as significant contributors to the decline and extinction of amphibian species. The main culprits currently considered are chytridiomycosis and Ranavirus. In Central America, highly endemic and geographical restricted terrestrial species may be at risk from these

High Sierra Ecosystems: The Role of Fish Stocking in Amphibian Declines

Science.gov (United States)

Kathleen Matthews

2003-01-01

With a rich diversity of aquatic habitats, including deep lakes, shallow ponds, and rushing streams, Dusy Basinin Sequoia-Kings Canyon National Parks typifies the high Sierra ecosystem where mountain yellow-legged frogs usually thrive. Yet throughout the Sierra, aquatic ecologist Kathleen Matthews found entire water basins empty of these amphibians. Comprehensive...

Detrimental effect of temperature increase on the fitness of an amphibian ( Lissotriton helveticus)

Science.gov (United States)

Galloy, Valérie; Denoël, Mathieu

2010-03-01

Increases of global temperatures have resulted in measurable shifts in the distribution, phenology and survival of some plant and animal species. However, the mechanisms showing links between global warming and biodiversity declines remain unclear. The aim of this study was to examine whether a key parameter of fitness, i.e. offspring number, could be affected by a temperature increase. To this end, we compared egg-laying traits at naturally occurring temperatures (14 °C, 18 °C and 22 °C) in palmate newts, Lissotriton helveticus. Our study suggests that water temperature increase has a negative effect on the fecundity of female newts. Females lay half as many eggs at high temperatures as they do at low temperatures, which results in a lower number of hatchlings. This study shows that global warming would affect amphibian populations. It complements other studies in pointing out that changes in phenology may not be driven only by warmer earlier temperatures but also by counter-selection during late-breeding, particularly in long-term breeders such as newts. More experimental studies should be carried out to understand the complex consequences of global warming and the proximate mechanisms of amphibian decline.

Saprolegniaceae identified on amphibian eggs throughout the Pacific Northwest, USA, by internal transcribed spacer sequences and phylogenetic analysis.

Science.gov (United States)

Petrisko, Jill E; Pearl, Christopher A; Pilliod, David S; Sheridan, Peter P; Williams, Charles F; Peterson, Charles R; Bury, R Bruce

2008-01-01

We assessed the diversity and phylogeny of Saprolegniaceae on amphibian eggs from the Pacific Northwest, with particular focus on Saprolegnia ferax, a species implicated in high egg mortality. We identified isolates from eggs of six amphibians with the internal transcribed spacer (ITS) and 5.8S gene regions and BLAST of the GenBank database. We identified 68 sequences as Saprolegniaceae and 43 sequences as true fungi from at least nine genera. Our phylogenetic analysis of the Saprolegniaceae included isolates within the genera Saprolegnia, Achlya and Leptolegnia. Our phylogeny grouped S. semihypogyna with Achlya rather than with the Saprolegnia reference sequences. We found only one isolate that grouped closely with S. ferax, and this came from a hatchery-raised salmon (Idaho) that we sampled opportunistically. We had representatives of 7-12 species and three genera of Saprolegniaceae on our amphibian eggs. Further work on the ecological roles of different species of Saprolegniaceae is needed to clarify their potential importance in amphibian egg mortality and potential links to population declines.

Reptiles as potential vectors and hosts of the amphibian pathogen Batrachochytrium dendrobatidis in Panama.

Science.gov (United States)

Kilburn, Vanessa L; Ibáñez, Roberto; Green, David M

2011-12-06

Chytridiomycosis, the disease caused by Batrachochytrium dendrobatidis, is considered to be a disease exclusively of amphibians. However, B. dendrobatidis may also be capable of persisting in the environment, and non-amphibian vectors or hosts may contribute to disease transmission. Reptiles living in close proximity to amphibians and sharing similar ecological traits could serve as vectors or reservoir hosts for B. dendrobatidis, harbouring the organism on their skin without succumbing to disease. We surveyed for the presence of B. dendrobatidis DNA among 211 lizards and 8 snakes at 8 sites at varying elevations in Panama where the syntopic amphibians were at pre-epizootic, epizootic or post-epizootic stages of chytridiomycosis. Detection of B. dendrobatidis DNA was done using qPCR analysis. Evidence of the amphibian pathogen was present at varying intensities in 29 of 79 examined Anolis humilis lizards (32%) and 9 of 101 A. lionotus lizards (9%), and in one individual each of the snakes Pliocercus euryzonus, Imantodes cenchoa, and Nothopsis rugosus. In general, B. dendrobatidis DNA prevalence among reptiles was positively correlated with the infection prevalence among co-occurring anuran amphibians at any particular site (r = 0.88, p = 0.004). These reptiles, therefore, may likely be vectors or reservoir hosts for B. dendrobatidis and could serve as disease transmission agents. Although there is no evidence of B. dendrobatidis disease-induced declines in reptiles, cases of coincidence of reptile and amphibian declines suggest this potentiality. Our study is the first to provide evidence of non-amphibian carriers for B. dendrobatidis in a natural Neotropical environment.

Unlocking the story in the swab: A new genotyping assay for the amphibian chytrid fungus Batrachochytrium dendrobatidis.

Science.gov (United States)

Byrne, Allison Q; Rothstein, Andrew P; Poorten, Thomas J; Erens, Jesse; Settles, Matthew L; Rosenblum, Erica Bree

2017-11-01

One of the most devastating emerging pathogens of wildlife is the chytrid fungus, Batrachochytrium dendrobatidis (Bd), which affects hundreds of amphibian species around the world. Genomic data from pure Bd cultures have advanced our understanding of Bd phylogenetics, genomic architecture and mechanisms of virulence. However, pure cultures are laborious to obtain and whole-genome sequencing is comparatively expensive, so relatively few isolates have been genetically characterized. Thus, we still know little about the genetic diversity of Bd in natural systems. The most common noninvasive method of sampling Bd from natural populations is to swab amphibian skin. Hundreds of thousands of swabs have been collected from amphibians around the world, but Bd DNA collected via swabs is often low in quality and/or quantity. In this study, we developed a custom Bd genotyping assay using the Fluidigm Access Array platform to amplify 192 carefully selected regions of the Bd genome. We obtained robust sequence data for pure Bd cultures and field-collected skin swabs. This new assay has the power to accurately discriminate among the major Bd clades, recovering the basic tree topology previously revealed using whole-genome data. Additionally, we established a critical value for initial Bd load for swab samples (150 Bd genomic equivalents) above which our assay performs well. By leveraging advances in microfluidic multiplex PCR technology and the globally distributed resource of amphibian swab samples, noninvasive skin swabs can now be used to address critical spatial and temporal questions about Bd and its effects on declining amphibian populations. © 2017 John Wiley & Sons Ltd.

Impending conservation crisis for Southeast Asian amphibians.

Science.gov (United States)

Rowley, Jodi; Brown, Rafe; Bain, Raoul; Kusrini, Mirza; Inger, Robert; Stuart, Bryan; Wogan, Guin; Thy, Neang; Chan-Ard, Tanya; Trung, Cao Tien; Diesmos, Arvin; Iskandar, Djoko T; Lau, Michael; Ming, Leong Tzi; Makchai, Sunchai; Truong, Nguyen Quang; Phimmachak, Somphouthone

2010-06-23

With an understudied amphibian fauna, the highest deforestation rate on the planet and high harvesting pressures, Southeast Asian amphibians are facing a conservation crisis. Owing to the overriding threat of habitat loss, the most critical conservation action required is the identification and strict protection of habitat assessed as having high amphibian species diversity and/or representing distinctive regional amphibian faunas. Long-term population monitoring, enhanced survey efforts, collection of basic biological and ecological information, continued taxonomic research and evaluation of the impact of commercial trade for food, medicine and pets are also needed. Strong involvement of regional stakeholders, students and professionals is essential to accomplish these actions.

Low prevalence of chytrid fungus (Batrachochytrium dendrobatidis) in amphibians of U.S. headwater streams

Science.gov (United States)

Hossack, Blake R.; Adams, Michael J.; Campbell Grant, Evan H.; Pearl, Chistopher A.; Bettaso, James B.; Barichivich, William J.; Lowe, Winsor H.; True, Kimberly; Ware, Joy L.; Corn, Paul Stephen

2010-01-01

Many declines of amphibian populations have been associated with chytridiomycosis, a disease caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd). Despite the relatively high prevalence of chytridiomycosis in stream amphibians globally, most surveys in North America have focused primarily on wetland-associated species, which are frequently infected. To better understand the distribution and prevalence of Bd in headwater amphibian communities, we sampled 452 tailed frogs (Ascaphus truei and Ascaphus montanus) and 304 stream salamanders (seven species in the Dicamptodontidae and Plethodontidae) for Bd in 38, first- to third-order streams in five montane areas across the United States. We tested for presence of Bd by using PCR on skin swabs from salamanders and metamorphosed tailed frogs or the oral disc of frog larvae. We detected Bd on only seven individuals (0.93%) in four streams. Based on our study and results from five other studies that have sampled headwater- or seep-associated amphibians in the United States, Bd has been detected on only 3% of 1,322 individuals from 21 species. These results differ strongly from surveys in Central America and Australia, where Bd is more prevalent on stream-breeding species, as well as results from wetland-associated anurans in the same regions of the United States that we sampled. Differences in the prevalence of Bd between stream- and wetland-associated amphibians in the United States may be related to species-specific variation in susceptibility to chytridiomycosis or habitat differences.

The Amphibian Research and Monitoring Initiative (ARMI): 5-year report

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Muths, Erin; Gallant, Alisa L.; Campbell Grant, Evan H.; Battaglin, William A.; Green, David E.; Staiger, Jennifer S.; Walls, Susan C.; Gunzburger, Margaret S.; Kearney, Rick F.

2006-01-01

The Amphibian Research and Monitoring Initiative (ARMI) is an innovative, multidisciplinary program that began in 2000 in response to a congressional directive for the Department of the Interior to address the issue of amphibian declines in the United States. ARMI’s formulation was cross-disciplinary, integrating U.S. Geological Survey scientists from Biology, Water, and Geography to develop a course of action (Corn and others, 2005a). The result has been an effective program with diverse, yet complementary, expertise.

Carotenoids and amphibians: effects on life history and susceptibility to the infectious pathogen, Batrachochytrium dendrobatidis.

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Cothran, Rickey D; Gervasi, Stephanie S; Murray, Cindy; French, Beverly J; Bradley, Paul W; Urbina, Jenny; Blaustein, Andrew R; Relyea, Rick A

2015-01-01

Carotenoids are considered beneficial nutrients because they provide increased immune capacity. Although carotenoid research has been conducted in many vertebrates, little research has been done in amphibians, a group that is experiencing global population declines from numerous causes, including disease. We raised two amphibian species through metamorphosis on three carotenoid diets to quantify the effects on life-history traits and post-metamorphic susceptibility to a fungal pathogen (Batrachochytrium dendrobatidis; Bd). Increased carotenoids had no effect on survival to metamorphosis in gray treefrogs (Hyla versicolor) but caused lower survival to metamorphosis in wood frogs [Lithobates sylvaticus (Rana sylvatica)]. Increased carotenoids caused both species to experience slower development and growth. When exposed to Bd after metamorphosis, wood frogs experienced high mortality, and the carotenoid diets had no mitigating effects. Gray treefrogs were less susceptible to Bd, which prevented an assessment of whether carotenoids could mitigate the effects of Bd. Moreover, carotenoids had no effect on pathogen load. As one of only a few studies examining the effects of carotenoids on amphibians and the first to examine potential interactions with Bd, our results suggest that carotenoids do not always serve amphibians in the many positive ways that have become the paradigm in other vertebrates.

From tails to toes: developing nonlethal tissue indicators of mercury exposure in five amphibian species.

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Pfleeger, Adam Z; Eagles-Smith, Collin A; Kowalski, Brandon M; Herring, Garth; Willacker, James J; Jackson, Allyson K; Pierce, John R

2016-04-01

Exposure to environmental contaminants has been implicated as a factor in global amphibian decline. Mercury (Hg) is a particularly widespread contaminant that biomagnifies in amphibians and can cause a suite of deleterious effects. However, monitoring contaminant exposure in amphibian tissues may conflict with conservation goals if lethal take is required. Thus, there is a need to develop non-lethal tissue sampling techniques to quantify contaminant exposure in amphibians. Some minimally invasive sampling techniques, such as toe-clipping, are common in population-genetic research, but it is unclear if these methods can adequately characterize contaminant exposure. We examined the relationships between mercury (Hg) concentrations in non-lethally sampled tissues and paired whole-bodies in five amphibian species. Specifically, we examined the utility of three different tail-clip sections from four salamander species and toe-clips from one anuran species. Both tail and toe-clips accurately predicted whole-body THg concentrations, but the relationships differed among species and the specific tail-clip section or toe that was used. Tail-clips comprised of the distal 0-2 cm segment performed the best across all salamander species, explaining between 82 and 92% of the variation in paired whole-body THg concentrations. Toe-clips were less effective predictors of frog THg concentrations, but THg concentrations in outer rear toes accounted for up to 79% of the variability in frog whole-body THg concentrations. These findings suggest non-lethal sampling of tails and toes has potential applications for monitoring contaminant exposure and risk in amphibians, but care must be taken to ensure consistent collection and interpretation of samples.

Effects of the amphibian chytrid fungus and four insecticides on Pacific treefrogs (Pseudacris regilla)

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Kleinhez, Peter; Boone, Michelle D.; Fellers, Gary

2012-01-01

Chemical contamination may influence host-pathogen interactions, which has implications for amphibian population declines. We examined the effects of four insecticides alone or as a mixture on development and metamorphosis of Pacific Treefrogs (Pseudacris regilla) in the presence or absence of the amphibian chytrid fungus (Batrachochytrium dendrobatidis [Bd]). Bd exposure had a negative impact on tadpole activity, survival to metamorphosis, time to metamorphosis, and time of tail absorption (with a marginally negative effect on mass at metamorphosis); however, no individuals tested positive for Bd at metamorphosis. The presence of sublethal concentrations of insecticides alone or in a mixture did not impact Pacific Treefrog activity as tadpoles, survival to metamorphosis, or time and size to metamorphosis. Insecticide exposure did not influence the effect of Bd exposure. Our study did not support our prediction that effects of Bd would be greater in the presence of expected environmental concentrations of insecticide(s), but it did show that Bd had negative effects on responses at metamorphosis that could reduce the quality of juveniles recruited into the population.

A Place to Call Home: Amphibian Use of Created and Restored Wetlands

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Donald J. Brown

2012-01-01

Full Text Available Loss and degradation of wetland habitats are major contributing factors to the global decline of amphibians. Creation and restoration of wetlands could be a valuable tool for increasing local amphibian species richness and abundance. We synthesized the peer-reviewed literature addressing amphibian use of created and restored wetlands, focusing on aquatic habitat, upland habitat, and wetland connectivity and configuration. Amphibian species richness or abundance at created and restored wetlands was either similar to or greater than reference wetlands in 89% of studies. Use of created and restored wetlands by individual species was driven by aquatic and terrestrial habitat preferences, as well as ability to disperse from source wetlands. We conclude that creating and restoring wetlands can be valuable tools for amphibian conservation. However, the ecological needs and preferences of target species must be considered to maximize the potential for successful colonization and long-term persistence.

Microevolution due to pollution in amphibians: A review on the genetic erosion hypothesis

International Nuclear Information System (INIS)

Fasola, E.; Ribeiro, R.; Lopes, I.

2015-01-01

The loss of genetic diversity, due to exposure to chemical contamination (genetic erosion), is a major threat to population viability. Genetic erosion is the loss of genetic variation: the loss of alleles determining the value of a specific trait or set of traits. Almost a third of the known amphibian species is considered to be endangered and a decrease of genetic variability can push them to the verge of extinction. This review indicates that loss of genetic variation due to chemical contamination has effects on: 1) fitness, 2) environmental plasticity, 3) co-tolerance mechanisms, 4) trade-off mechanisms, and 5) tolerance to pathogens in amphibian populations. - Highlights: • Effects of environmental stressors on the genetic diversity of natural populations of amphibians have usually been underestimated. • Environmental pollution may reduce the genetic diversity of exposed amphibian populations. • Genetic erosion can lead to reduced fitness and lack of adaptability to a changing environment. - Contaminant-driven genetic erosion is a major threat to population viability in amphibians

Practitioner and scientist perceptions of successful amphibian conservation.

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Meredith, Helen M R; St John, Freya A V; Collen, Ben; Black, Simon A; Griffiths, Richard A

2018-04-01

Conservation requires successful outcomes. However, success is perceived in many different ways depending on the desired outcome. Through a questionnaire survey, we examined perceptions of success among 355 scientists and practitioners working on amphibian conservation from over 150 organizations in more than 50 countries. We also sought to identify how different types of conservation actions and respondent experience and background influenced perceptions. Respondents identified 4 types of success: species and habitat improvements (84% of respondents); effective program management (36%); outreach initiatives such as education and public engagement (25%); and the application of science-based conservation (15%). The most significant factor influencing overall perceived success was reducing threats. Capacity building was rated least important. Perceptions were influenced by experience, professional affiliation, involvement in conservation practice, and country of residence. More experienced practitioners associated success with improvements to species and habitats and less so with education and engagement initiatives. Although science-based conservation was rated as important, this factor declined in importance as the number of programs a respondent participated in increased, particularly among those from less economically developed countries. The ultimate measure of conservation success-population recovery-may be difficult to measure in many amphibians; difficult to relate to the conservation actions intended to drive it; and difficult to achieve within conventional funding time frames. The relaunched Amphibian Conservation Action Plan provides a framework for capturing lower level processes and outcomes, identifying gaps, and measuring progress. © 2017 The Authors. Conservation Biology published by Wiley Periodicals, Inc. on behalf of Society for Conservation Biology.

NIDI scenario. Strong population decline in China

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de Beer, J.A.A.

2016-01-01

United Nations projections assume that by the end of this century one third of the world population will live in India, China or Nigeria. While population growth in India will slow down and the population size of China will decline, population growth in Nigeria will accelerate. A new NIDI scenario

Endemic infection of the amphibian chytrid fungus in a frog community post-decline.

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Richard W R Retallick

2004-11-01

Full Text Available The chytrid fungus Batrachochytrium dendrobatidis has been implicated in the decline and extinction of numerous frog species worldwide. In Queensland, Australia, it has been proposed as the cause of the decline or apparent extinction of at least 14 high-elevation rainforest frog species. One of these, Taudactylus eungellensis, disappeared from rainforest streams in Eungella National Park in 1985-1986, but a few remnant populations were subsequently discovered. Here, we report the analysis of B. dendrobatidis infections in toe tips of T. eungellensis and sympatric species collected in a mark-recapture study between 1994 and 1998. This longitudinal study of the fungus in individually marked frogs sheds new light on the effect of this threatening infectious process in field, as distinct from laboratory, conditions. We found a seasonal peak of infection in the cooler months, with no evidence of interannual variation. The overall prevalence of infection was 18% in T. eungellensis and 28% in Litoria wilcoxii/jungguy, a sympatric frog that appeared not to decline in 1985-1986. No infection was found in any of the other sympatric species. Most importantly, we found no consistent evidence of lower survival in T. eungellensis that were infected at the time of first capture, compared with uninfected individuals. These results refute the hypothesis that remnant populations of T. eungellensis recovered after a B. dendrobatidis epidemic because the pathogen had disappeared. They show that populations of T. eungellensis now persist with stable, endemic infections of B. dendrobatidis.

Endemic infection of the amphibian chytrid fungus in a frog community post-decline.

Science.gov (United States)

Retallick, Richard W R; McCallum, Hamish; Speare, Rick

2004-11-01

The chytrid fungus Batrachochytrium dendrobatidis has been implicated in the decline and extinction of numerous frog species worldwide. In Queensland, Australia, it has been proposed as the cause of the decline or apparent extinction of at least 14 high-elevation rainforest frog species. One of these, Taudactylus eungellensis, disappeared from rainforest streams in Eungella National Park in 1985-1986, but a few remnant populations were subsequently discovered. Here, we report the analysis of B. dendrobatidis infections in toe tips of T. eungellensis and sympatric species collected in a mark-recapture study between 1994 and 1998. This longitudinal study of the fungus in individually marked frogs sheds new light on the effect of this threatening infectious process in field, as distinct from laboratory, conditions. We found a seasonal peak of infection in the cooler months, with no evidence of interannual variation. The overall prevalence of infection was 18% in T. eungellensis and 28% in Litoria wilcoxii/jungguy, a sympatric frog that appeared not to decline in 1985-1986. No infection was found in any of the other sympatric species. Most importantly, we found no consistent evidence of lower survival in T. eungellensis that were infected at the time of first capture, compared with uninfected individuals. These results refute the hypothesis that remnant populations of T. eungellensis recovered after a B. dendrobatidis epidemic because the pathogen had disappeared. They show that populations of T. eungellensis now persist with stable, endemic infections of B. dendrobatidis.

The metamorphosis of amphibian toxicogenomics

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Caren eHelbing

2012-03-01

Full Text Available Amphibians are important vertebrates in toxicology often representing both aquatic and terrestrial forms within the life history of the same species. Of the thousands of species, only two have substantial genomics resources: the recently published genome of the Pipid, Xenopus (Silurana tropicalis, and transcript information (and ongoing genome sequencing project of Xenopus laevis. However, many more species representative of regional ecological niches and life strategies are used in toxicology worldwide. Since Xenopus species diverged from the most populous frog family, the Ranidae, ~200 million years ago, there are notable differences between them and the even more distant Caudates (salamanders and Caecilians. These differences include genome size, gene composition, and extent of polyploidization. Application of toxicogenomics to amphibians requires the mobilization of resources and expertise to develop de novo sequence assemblies and analysis strategies for a broader range of amphibian species. The present mini-review will present the advances in toxicogenomics as pertains to amphibians with particular emphasis upon the development and use of genomic techniques (inclusive of transcriptomics, proteomics, and metabolomics and the challenges inherent therein.

Regional decline of an iconic amphibian associated with elevation, land-use change, and invasive species.

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Johnson, Pieter T J; McKenzie, Valerie J; Peterson, Anna C; Kerby, Jacob L; Brown, Jennifer; Blaustein, Andrew R; Jackson, Tina

2011-06-01

Ecological theory predicts that species with restricted geographic ranges will have the highest probability of extinction, but species with extensive distributions and high population densities can also exhibit widespread population losses. In the western United States populations of northern leopard frogs (Lithobates pipiens)-historically one of the most widespread frogs in North America-have declined dramatically in abundance and geographic distribution. To assess the status of leopard frogs in Colorado and evaluate causes of decline, we coupled statewide surveys of 196 historically occupied sites with intensive sampling of 274 wetlands stratified by land use. We used an information-theoretic approach to evaluate the contributions of factors at multiple spatial extents in explaining the contemporary distribution of leopard frogs. Our results indicate leopard frogs have declined in Colorado, but this decline was regionally variable. The lowest proportion of occupied wetlands occurred in eastern Colorado (2-28%), coincident with urban development and colonization by non-native bullfrogs (Lithobates catesbeianus). Variables at several spatial extents explained observed leopard frog distributional patterns. In low-elevation wetlands introduced fishes, bullfrogs, and urbanization or suburbanization associated negatively with leopard frog occurrence, whereas wetland area was positively associated with occurrence. Leopard frogs were more abundant and widespread west of the Continental Divide, where urban development and bullfrog abundance were low. Although the pathogenic chytrid Batrachochytrium dendrobatidis (Bd) was not selected in our best-supported models, the nearly complete extirpation of leopard frogs from montane wetlands could reflect the individual or interactive effects of Bd and climate patterns. Our results highlight the importance of considering multiple, competing hypotheses to explain species declines, particularly when implicated factors operate at

Individualistic population responses of five frog species in two changing tropical environments over time.

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Mason J Ryan

Full Text Available Roughly 40% of amphibian species are in decline with habitat loss, disease, and climate change being the most cited threats. Heterogeneity of extrinsic (e.g. climate and intrinsic (e.g. local adaptations factors across a species' range should influence population response to climate change and other threats. Here we examine relative detectability changes for five direct-developing leaf litter frogs between 42-year sampling periods at one Lowland Tropical Forest site (51 m.a.s.l. and one Premontane Wet Forest site (1100 m.a.s.l. in southwest Costa Rica. We identify individualistic changes in relative detectability among populations between sampling periods at different elevations. Both common and rare species showed site-specific declines, and no species exhibited significant declines at both sites. Detection changes are correlated with changes in temperature, dry season rainfall, and leaf litter depth since 1969. Our study species share Least Concern conservation status, life history traits, and close phylogenetic relationship, yet their populations changed individualistically both within and among species. These results counter current views of the uniformity or predictability of amphibian decline response and suggest additional complexity for conservation decisions.

Genetic evidence for a high diversity and wide distribution of endemic strains of the pathogenic chytrid fungus Batrachochytrium dendrobatidis in wild Asian amphibians.

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Bataille, Arnaud; Fong, Jonathan J; Cha, Moonsuk; Wogan, Guinevere O U; Baek, Hae Jun; Lee, Hang; Min, Mi-Sook; Waldman, Bruce

2013-08-01

Population declines and extinctions of amphibians have been attributed to the chytrid fungus Batrachochytrium dendrobatidis (Bd), especially one globally emerging recombinant lineage ('Bd-GPL'). We used PCR assays that target the ribosomal internal transcribed spacer region (ITS) of Bd to determine the prevalence and genetic diversity of Bd in South Korea, where Bd is widely distributed but is not known to cause morbidity or mortality in wild populations. We isolated Korean Bd strains from native amphibians with low infection loads and compared them to known worldwide Bd strains using 19 polymorphic SNP and microsatellite loci. Bd prevalence ranged between 12.5 and 48.0%, in 11 of 17 native Korean species, and 24.7% in the introduced bullfrog Lithobates catesbeianus. Based on ITS sequence variation, 47 of the 50 identified Korean haplotypes formed a group closely associated with a native Brazilian Bd lineage, separated from the Bd-GPL lineage. However, multilocus genotyping of three Korean Bd isolates revealed strong divergence from both Bd-GPL and the native Brazilian Bd lineages. Thus, the ITS region resolves genotypes that diverge from Bd-GPL but otherwise generates ambiguous phylogenies. Our results point to the presence of highly diversified endemic strains of Bd across Asian amphibian species. The rarity of Bd-GPL-associated haplotypes suggests that either this lineage was introduced into Korea only recently or Bd-GPL has been outcompeted by native Bd strains. Our results highlight the need to consider possible complex interactions among native Bd lineages, Bd-GPL and their associated amphibian hosts when assessing the spread and impact of Bd-GPL on worldwide amphibian populations. © 2013 John Wiley & Sons Ltd.

Amphibian molecular ecology and how it has informed conservation.

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McCartney-Melstad, Evan; Shaffer, H Bradley

2015-10-01

Molecular ecology has become one of the key tools in the modern conservationist's kit. Here we review three areas where molecular ecology has been applied to amphibian conservation: genes on landscapes, within-population processes, and genes that matter. We summarize relevant analytical methods, recent important studies from the amphibian literature, and conservation implications for each section. Finally, we include five in-depth examples of how molecular ecology has been successfully applied to specific amphibian systems. © 2015 John Wiley & Sons Ltd.

Quantitative Proteomics of an Amphibian Pathogen, Batrachochytrium dendrobatidis, following Exposure to Thyroid Hormone.

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Thekkiniath, Jose; Zabet-Moghaddam, Masoud; Kottapalli, Kameswara Rao; Pasham, Mithun R; San Francisco, Susan; San Francisco, Michael

2015-01-01

Batrachochytrium dendrobatidis (Bd), a chytrid fungus, has increasingly been implicated as a major factor in the worldwide decline of amphibian populations. The fungus causes chytridiomycosis in susceptible species leading to massive die-offs of adult amphibians. Although Bd infects the keratinized mouthparts of tadpoles and negatively affects foraging behavior, these infections are non-lethal. An important morphogen controlling amphibian metamorphosis is thyroid hormone (T3). Tadpoles may be infected with Bd and the fungus may be exposed to T3 during metamorphosis. We hypothesize that exposure of Bd to T3 may induce the expression of factors associated with host colonization and pathogenicity. We utilized a proteomics approach to better understand the dynamics of the Bd-T3 interaction. Using liquid chromatography-mass spectrometry (LC-MS), we generated a data set of a large number of cytoplasmic and membrane proteins following exposure of Bd to T3. From these data, we identified a total of 263 proteins whose expression was significantly changed following T3 exposure. We provide evidence for expression of an array of proteins that may play key roles in both genomic and non-genomic actions of T3 in Bd. Additionally, our proteomics study shows an increase in several proteins including proteases and a class of uncommon crinkler and crinkler-like effector proteins suggesting their importance in Bd pathogenicity as well as those involved in metabolism and energy transfer, protein fate, transport and stress responses. This approach provides insights into the mechanistic basis of the Bd-amphibian interaction following T3 exposure.

Quantitative Proteomics of an Amphibian Pathogen, Batrachochytrium dendrobatidis, following Exposure to Thyroid Hormone.

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Jose Thekkiniath

Full Text Available Batrachochytrium dendrobatidis (Bd, a chytrid fungus, has increasingly been implicated as a major factor in the worldwide decline of amphibian populations. The fungus causes chytridiomycosis in susceptible species leading to massive die-offs of adult amphibians. Although Bd infects the keratinized mouthparts of tadpoles and negatively affects foraging behavior, these infections are non-lethal. An important morphogen controlling amphibian metamorphosis is thyroid hormone (T3. Tadpoles may be infected with Bd and the fungus may be exposed to T3 during metamorphosis. We hypothesize that exposure of Bd to T3 may induce the expression of factors associated with host colonization and pathogenicity. We utilized a proteomics approach to better understand the dynamics of the Bd-T3 interaction. Using liquid chromatography-mass spectrometry (LC-MS, we generated a data set of a large number of cytoplasmic and membrane proteins following exposure of Bd to T3. From these data, we identified a total of 263 proteins whose expression was significantly changed following T3 exposure. We provide evidence for expression of an array of proteins that may play key roles in both genomic and non-genomic actions of T3 in Bd. Additionally, our proteomics study shows an increase in several proteins including proteases and a class of uncommon crinkler and crinkler-like effector proteins suggesting their importance in Bd pathogenicity as well as those involved in metabolism and energy transfer, protein fate, transport and stress responses. This approach provides insights into the mechanistic basis of the Bd-amphibian interaction following T3 exposure.

Female sexual arousal in amphibians.

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Wilczynski, Walter; Lynch, Kathleen S

2011-05-01

Rather than being a static, species specific trait, reproductive behavior in female amphibians is variable within an individual during the breeding season when females are capable of reproductive activity. Changes in receptivity coincide with changes in circulating estrogen. Estrogen is highest at the point when females are ready to choose a male and lay eggs. At this time female receptivity (her probability of responding to a male vocal signal) is highest and her selectivity among conspecific calls (measured by her probability of responding to a degraded or otherwise usually unattractive male signal) is lowest. These changes occur even though females retain the ability to discriminate different acoustic characteristics of various conspecific calls. After releasing her eggs, female amphibians quickly become less receptive and more choosy in terms of their responses to male sexual advertisement signals. Male vocal signals stimulate both behavior and estrogen changes in amphibian females making mating more probable. The changes in female reproductive behavior are the same as those generally accepted as indicative of a change in female sexual arousal leading to copulation. They are situationally triggered, gated by interactions with males, and decline with the consummation of sexual reproduction with a chosen male. The changes can be triggered by either internal physiological state or by the presence of stimuli presented by males, and the same stimuli change both behavior and physiological (endocrine) state in such a way as to make acceptance of a male more likely. Thus amphibian females demonstrate many of the same general characteristics of changing female sexual state that in mammals indicate sexual arousal. Copyright © 2010 Elsevier Inc. All rights reserved.

Developments in amphibian captive breeding and reintroduction programs.

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Harding, Gemma; Griffiths, Richard A; Pavajeau, Lissette

2016-04-01

Captive breeding and reintroduction remain high profile but controversial conservation interventions. It is important to understand how such programs develop and respond to strategic conservation initiatives. We analyzed the contribution to conservation made by amphibian captive breeding and reintroduction since the launch of the International Union for Conservation of Nature (IUCN) Amphibian Conservation Action Plan (ACAP) in 2007. We assembled data on amphibian captive breeding and reintroduction from a variety of sources including the Amphibian Ark database and the IUCN Red List. We also carried out systematic searches of Web of Science, JSTOR, and Google Scholar for relevant literature. Relative to data collected from 1966 to 2006, the number of species involved in captive breeding and reintroduction projects increased by 57% in the 7 years since release of the ACAP. However, there have been relatively few new reintroductions over this period; most programs have focused on securing captive-assurance populations (i.e., species taken into captivity as a precaution against extinctions in the wild) and conservation-related research. There has been a shift to a broader representation of frogs, salamanders, and caecilians within programs and an increasing emphasis on threatened species. There has been a relative increase of species in programs from Central and South America and the Caribbean, where amphibian biodiversity is high. About half of the programs involve zoos and aquaria with a similar proportion represented in specialist facilities run by governmental or nongovernmental agencies. Despite successful reintroduction often being regarded as the ultimate milestone for such programs, the irreversibility of many current threats to amphibians may make this an impractical goal. Instead, research on captive assurance populations may be needed to develop imaginative solutions to enable amphibians to survive alongside current, emerging, and future threats. © 2015

Whether the weather drives patterns of endemic amphibian chytridiomycosis: a pathogen proliferation approach.

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Kris A Murray

Full Text Available The pandemic amphibian disease chytridiomycosis often exhibits strong seasonality in both prevalence and disease-associated mortality once it becomes endemic. One hypothesis that could explain this temporal pattern is that simple weather-driven pathogen proliferation (population growth is a major driver of chytridiomycosis disease dynamics. Despite various elaborations of this hypothesis in the literature for explaining amphibian declines (e.g., the chytrid thermal-optimum hypothesis it has not been formally tested on infection patterns in the wild. In this study we developed a simple process-based model to simulate the growth of the pathogen Batrachochytrium dendrobatidis (Bd under varying weather conditions to provide an a priori test of a weather-linked pathogen proliferation hypothesis for endemic chytridiomycosis. We found strong support for several predictions of the proliferation hypothesis when applied to our model species, Litoria pearsoniana, sampled across multiple sites and years: the weather-driven simulations of pathogen growth potential (represented as a growth index in the 30 days prior to sampling; GI30 were positively related to both the prevalence and intensity of Bd infections, which were themselves strongly and positively correlated. In addition, a machine-learning classifier achieved ~72% success in classifying positive qPCR results when utilising just three informative predictors 1 GI30, 2 frog body size and 3 rain on the day of sampling. Hence, while intrinsic traits of the individuals sampled (species, size, sex and nuisance sampling variables (rainfall when sampling influenced infection patterns obtained when sampling via qPCR, our results also strongly suggest that weather-linked pathogen proliferation plays a key role in the infection dynamics of endemic chytridiomycosis in our study system. Predictive applications of the model include surveillance design, outbreak preparedness and response, climate change scenario

Whether the weather drives patterns of endemic amphibian chytridiomycosis: a pathogen proliferation approach.

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Murray, Kris A; Skerratt, Lee F; Garland, Stephen; Kriticos, Darren; McCallum, Hamish

2013-01-01

The pandemic amphibian disease chytridiomycosis often exhibits strong seasonality in both prevalence and disease-associated mortality once it becomes endemic. One hypothesis that could explain this temporal pattern is that simple weather-driven pathogen proliferation (population growth) is a major driver of chytridiomycosis disease dynamics. Despite various elaborations of this hypothesis in the literature for explaining amphibian declines (e.g., the chytrid thermal-optimum hypothesis) it has not been formally tested on infection patterns in the wild. In this study we developed a simple process-based model to simulate the growth of the pathogen Batrachochytrium dendrobatidis (Bd) under varying weather conditions to provide an a priori test of a weather-linked pathogen proliferation hypothesis for endemic chytridiomycosis. We found strong support for several predictions of the proliferation hypothesis when applied to our model species, Litoria pearsoniana, sampled across multiple sites and years: the weather-driven simulations of pathogen growth potential (represented as a growth index in the 30 days prior to sampling; GI30) were positively related to both the prevalence and intensity of Bd infections, which were themselves strongly and positively correlated. In addition, a machine-learning classifier achieved ~72% success in classifying positive qPCR results when utilising just three informative predictors 1) GI30, 2) frog body size and 3) rain on the day of sampling. Hence, while intrinsic traits of the individuals sampled (species, size, sex) and nuisance sampling variables (rainfall when sampling) influenced infection patterns obtained when sampling via qPCR, our results also strongly suggest that weather-linked pathogen proliferation plays a key role in the infection dynamics of endemic chytridiomycosis in our study system. Predictive applications of the model include surveillance design, outbreak preparedness and response, climate change scenario modelling and

Cryopreservation and other assisted reproductive technologies for the conservation of threatened amphibians and reptiles: bringing the ARTs up to speed.

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Clulow, John; Clulow, Simon

2016-06-01

Amphibians and reptiles are experiencing serious declines, with the number of threatened species and extinctions growing rapidly as the modern biodiversity crisis unfolds. For amphibians, the panzootic of chytridiomycosis is a major driver. For reptiles, habitat loss and harvesting from the wild are key threats. Cryopreservation and other assisted reproductive technologies (ARTs) could play a role in slowing the loss of amphibian and reptile biodiversity and managing threatened populations through genome storage and the production of live animals from stored material. These vertebrate classes are at different stages of development in cryopreservation and other ARTs, and each class faces different technical challenges arising from the separate evolutionary end-points of their reproductive biology. For amphibians, the generation of live offspring from cryopreserved spermatozoa has been achieved, but the cryopreservation of oocytes and embryos remains elusive. With reptiles, spermatozoa have been cryopreserved in a few species, but no offspring from cryopreserved spermatozoa have been reported, and the generation of live young from AI has only occurred in a small number of species. Cryopreservation and ARTs are more developed and advanced for amphibians than reptiles. Future work on both groups needs to concentrate on achieving proof of concept examples that demonstrate the use of genome storage and ARTs in successfully recovering threatened species to increase awareness and support for this approach to conservation.

Optimizing protection efforts for amphibian conservation in Mediterranean landscapes

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García-Muñoz, Enrique; Ceacero, Francisco; Carretero, Miguel A.; Pedrajas-Pulido, Luis; Parra, Gema; Guerrero, Francisco

2013-05-01

Amphibians epitomize the modern biodiversity crisis, and attract great attention from the scientific community since a complex puzzle of factors has influence on their disappearance. However, these factors are multiple and spatially variable, and declining in each locality is due to a particular combination of causes. This study shows a suitable statistical procedure to determine threats to amphibian species in medium size administrative areas. For our study case, ten biological and ecological variables feasible to affect the survival of 15 amphibian species were categorized and reduced through Principal Component Analysis. The principal components extracted were related to ecological plasticity, reproductive potential, and specificity of breeding habitats. Finally, the factor scores of species were joined in a presence-absence matrix that gives us information to identify where and why conservation management are requires. In summary, this methodology provides the necessary information to maximize benefits of conservation measures in small areas by identifying which ecological factors need management efforts and where should we focus them on.

cytogenetic effects in populations of amphibians Rana arvalis living on the radio-contaminated area

Energy Technology Data Exchange (ETDEWEB)

Yushkova, E.; Bodnar, I.; Zainullin, V. [Institute of Biology of Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences (Russian Federation)

2014-07-01

of all types of DNA damages in blood cells of amphibians exposed to radioactive impact environment was noted. Thus the reaction of natural populations of amphibians conditional increased levels of cytogenetic damages in their cells is determined the long-term of action by factors of radioactive contamination of the environment. This work was supported by Integration project of the Ural Branch of the Russian Academy of Sciences (No. 12-I-4-2006). Document available in abstract form only. (authors)

Roles of patch characteristics, drought frequency, and restoration in long-term trends of a widespread amphibian

Science.gov (United States)

Hossack, Blake R.; Adams, Michael J.; Pearl, Christopher A.; Pilliod, David S.; Corn, P. Stephen; , KRISTINE W. WILSON; , EVELYN L. BULL; , KRISTIN LOHR; , DEBRA PATLA; , JASON JONES

2013-01-01

Despite the high profile of amphibian declines and the increasing threat of drought and fragmentation to aquatic ecosystems, few studies have examined long-term rates of change for a single species across a large geographic area. We analyzed growth in annual egg-mass counts of the Columbia spotted frog (Rana luteiventris) across the northwestern United States, an area encompassing 3 genetic clades. On the basis of data collected by multiple partners from 98 water bodies between 1991 and 2011, we used state-space and linear-regression models to measure effects of patch characteristics, frequency of summer drought, and wetland restoration on population growth. Abundance increased in the 2 clades with greatest decline history, but declined where populations are considered most secure. Population growth was negatively associated with temporary hydroperiods and landscape modification (measured by the human footprint index), but was similar in modified and natural water bodies. The effect of drought was mediated by the size of the water body: populations in large water bodies maintained positive growth despite drought, whereas drought magnified declines in small water bodies. Rapid growth in restored wetlands in areas of historical population declines provided strong evidence of successful management. Our results highlight the importance of maintaining large areas of habitat and underscore the greater vulnerability of small areas of habitat to environmental stochasticity. Similar long-term growth rates in modified and natural water bodies and rapid, positive responses to restoration suggest pond construction and other forms of management can effectively increase population growth. These tools are likely to become increasingly important to mitigate effects of increased drought expected from global climate change.

Amphibian commerce as a likely source of pathogen pollution.

Science.gov (United States)

Picco, Angela M; Collins, James P

2008-12-01

The commercial trade of wildlife occurs on a global scale. In addition to removing animals from their native populations, this trade may lead to the release and subsequent introduction of nonindigenous species and the pathogens they carry. Emerging infectious diseases, such as chytridiomycosis caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), and ranaviral disease have spread with global trade in amphibians and are linked to amphibian declines and die-offs worldwide, which suggests that the commercial trade in amphibians may be a source of pathogen pollution. We screened tiger salamanders involved in the bait trade in the western United States for both ranaviruses and Bd with polymerase chain reaction and used oral reports from bait shops and ranavirus DNA sequences from infected bait salamanders to determine how these animals and their pathogens are moved geographically by commerce. In addition, we conducted 2 surveys of anglers to determine how often tiger salamanders are used as bait and how often they are released into fishing waters by anglers, and organized bait-shop surveys to determine whether tiger salamanders are released back into the wild after being housed in bait shops. Ranaviruses were detected in the tiger salamander bait trade in Arizona, Colorado, and New Mexico, and Bd was detected in Arizona bait shops. Ranaviruses were spread geographically through the bait trade. All tiger salamanders in the bait trade were collected from the wild, and in general they moved east to west and north to south, bringing with them their multiple ranavirus strains. Finally, 26-73% of anglers used tiger salamanders as fishing bait, 26-67% of anglers released tiger salamanders bought as bait into fishing waters, and 4% of bait shops released tiger salamanders back into the wild after they were housed in shops with infected animals. The tiger salamander bait trade in the western United States is a useful model for understanding the consequences of the

The Current and Historical Distribution of Special Status Amphibians at the Livermore Site and Site 300

Energy Technology Data Exchange (ETDEWEB)

Hattem, M V; Paterson, L; Woollett, J

2008-08-20

65 surveys were completed in 2002 to assess the current distribution of special status amphibians at the Lawrence Livermore National Laboratory's (LLNL) Livermore Site and Site 300. Combined with historical information from previous years, the information presented herein illustrates the dynamic and probable risk that amphibian populations face at both sites. The Livermore Site is developed and in stark contrast to the mostly undeveloped Site 300. Yet both sites have significant issues threatening the long-term sustainability of their respective amphibian populations. Livermore Site amphibians are presented with a suite of challenges inherent of urban interfaces, most predictably the bullfrog (Rana catesbeiana), while Site 300's erosion issues and periodic feral pig (Sus scrofa) infestations reduce and threaten populations. The long-term sustainability of LLNL's special status amphibians will require active management and resource commitment to maintain and restore amphibian habitat at both sites.

High dispersal in a frog species suggests that it is vulnerable to habitat fragmentation

OpenAIRE

Funk, W. Chris; Greene, Allison E; Corn, Paul Stephen; Allendorf, Fred W

2005-01-01

Global losses of amphibian populations are a major conservation concern and their causes have generated substantial debate. Habitat fragmentation is considered one important cause of amphibian decline. However, if fragmentation is to be invoked as a mechanism of amphibian decline, it must first be established that dispersal is prevalent among contiguous amphibian populations using formal movement estimators. In contrast, if dispersal is naturally low in amphibians, fragmentation can be disreg...

Effects of experimental canopy manipulation on amphibian egg deposition

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Zachary I. Felix; Yong Wang; Callie J. Schweitzer

2010-01-01

Although effects of forest management on amphibians are relatively well studied, few studies have examined how these practices affect egg deposition by adults, which can impact population recruitment. We quantified the effects of 4 canopy tree-retention treatments on amphibian oviposition patterns in clusters of 60-L aquatic mesocosms located in each treatment. We also...

Patterns and biases in climate change research on amphibians and reptiles: a systematic review.

Science.gov (United States)

Winter, Maiken; Fiedler, Wolfgang; Hochachka, Wesley M; Koehncke, Arnulf; Meiri, Shai; De la Riva, Ignacio

2016-09-01

Climate change probably has severe impacts on animal populations, but demonstrating a causal link can be difficult because of potential influences by additional factors. Assessing global impacts of climate change effects may also be hampered by narrow taxonomic and geographical research foci. We review studies on the effects of climate change on populations of amphibians and reptiles to assess climate change effects and potential biases associated with the body of work that has been conducted within the last decade. We use data from 104 studies regarding the effect of climate on 313 species, from 464 species-study combinations. Climate change effects were reported in 65% of studies. Climate change was identified as causing population declines or range restrictions in half of the cases. The probability of identifying an effect of climate change varied among regions, taxa and research methods. Climatic effects were equally prevalent in studies exclusively investigating climate factors (more than 50% of studies) and in studies including additional factors, thus bolstering confidence in the results of studies exclusively examining effects of climate change. Our analyses reveal biases with respect to geography, taxonomy and research question, making global conclusions impossible. Additional research should focus on under-represented regions, taxa and questions. Conservation and climate policy should consider the documented harm climate change causes reptiles and amphibians.

Combined exposure to ambient UVB radiation and nitrite negatively affects survival of amphibian early life stages

International Nuclear Information System (INIS)

Macias, Guadalupe; Marco, Adolfo; Blaustein, Andrew R.

2007-01-01

Many aquatic species are sensitive to ambient levels of ultraviolet-B radiation (UVB) and chemical fertilizers. However, recent studies indicate that the interaction among multiple stressors acting simultaneously could be contributing to the population declines of some animal species. Therefore, we tested the potential synergistic effects between ambient levels of UVB and a contaminant, sodium nitrite in the larvae of two amphibian species, the common European toad Bufo bufo and the Iberian green frog Rana perezi. We studied R. perezi from both mountain and coastal populations to examine if populations of the same species varied in their response to stressors in different habitats. Both species were sensitive to the two stressors acting alone, but the interaction between the two stressors caused a multiplicative impact on tadpole survival. For B. bufo, the combination of UVB and nitrite was up to seven times more lethal than mortality for each stressor alone. In a coastal wetland, the combination of UVB and nitrite was four times more toxic for R. perezi than the sum of the effect on mortality for each stressor alone. One mg/L of nitrite killed half the population of R. perezi at Gredos Mountains at day 10 in the absence of UVB. In the presence of UVB, 50% of the tadpoles from the same experiment died at day 7. Similar toxic response were found for R. perezi in two highly contrasted environments suggesting this synergistic interaction can be a widespread phenomenon. The interaction of excess chemical fertilizers and manure with ambient UVB radiation could be contributing to the global decline of some amphibian species. We suggest that potential exposure to UVB radiation be accounted for when assessing water quality criteria regarding nitrite pollution

Combined exposure to ambient UVB radiation and nitrite negatively affects survival of amphibian early life stages

Energy Technology Data Exchange (ETDEWEB)

Macias, Guadalupe [Donana Biological Station, CSIC, Spanish Council for Scientific Research. P.O. Box 1056, Sevilla 41013 (Spain); Marco, Adolfo [Donana Biological Station, CSIC, Spanish Council for Scientific Research. P.O. Box 1056, Sevilla 41013 (Spain)], E-mail: amarco@ebd.csic.es; Blaustein, Andrew R. [Department of Zoology, Oregon State University, Corvallis, Oregon, 97331 (United States)

2007-10-15

Many aquatic species are sensitive to ambient levels of ultraviolet-B radiation (UVB) and chemical fertilizers. However, recent studies indicate that the interaction among multiple stressors acting simultaneously could be contributing to the population declines of some animal species. Therefore, we tested the potential synergistic effects between ambient levels of UVB and a contaminant, sodium nitrite in the larvae of two amphibian species, the common European toad Bufo bufo and the Iberian green frog Rana perezi. We studied R. perezi from both mountain and coastal populations to examine if populations of the same species varied in their response to stressors in different habitats. Both species were sensitive to the two stressors acting alone, but the interaction between the two stressors caused a multiplicative impact on tadpole survival. For B. bufo, the combination of UVB and nitrite was up to seven times more lethal than mortality for each stressor alone. In a coastal wetland, the combination of UVB and nitrite was four times more toxic for R. perezi than the sum of the effect on mortality for each stressor alone. One mg/L of nitrite killed half the population of R. perezi at Gredos Mountains at day 10 in the absence of UVB. In the presence of UVB, 50% of the tadpoles from the same experiment died at day 7. Similar toxic response were found for R. perezi in two highly contrasted environments suggesting this synergistic interaction can be a widespread phenomenon. The interaction of excess chemical fertilizers and manure with ambient UVB radiation could be contributing to the global decline of some amphibian species. We suggest that potential exposure to UVB radiation be accounted for when assessing water quality criteria regarding nitrite pollution.

Human Population Decline in North America during the Younger Dryas

Science.gov (United States)

Anderson, D. G.; Goodyear, A. C.; Stafford, T. W., Jr.; Kennett, J.; West, A.

2009-12-01

There is ongoing debate about a possible human population decline or contraction at the onset of the Younger Dryas (YD) at 12.9 ka. We used two methods to test whether the YD affected human population levels: (1) frequency analyses of Paleoindian projectile points, and (2) summed probability analyses of radiocarbon (14C) dates. The results suggest that a significant decline or reorganization of human populations occurred at 12.9 ka, continued through the initial centuries of the YD chronozone, then rebounded by the end of the YD. FREQUENCY ANALYSES: This method employed projectile point data from the Paleoindian Database of the Americas (PIDBA, http://pidba.utk.edu). We tallied diagnostic projectile points and obtained larger totals for Clovis points than for immediately post-Clovis points, which share an instrument-assisted fluting technique, typically using pressure or indirect percussion. Gainey, Vail, Debert, Redstone, and Cumberland point-styles utilized this method and are comparable to the Folsom style. For the SE U.S., the ratio of Clovis points (n=1993) to post-Clovis points (n=947) reveals a point decline of 52%. For the Great Plains, a comparison of Clovis and fluted points (n=4020) to Folsom points (n=2527) shows a point decline of 37%, which may translate into a population contraction of similar magnitude. In addition, eight major Clovis lithic quarry sites in the SE U.S. exhibit little to no evidence for immediate post-Clovis occupations, implying a major population decline. SUMMED PROBABILITIES: This method involved calibrating relevant 14C dates and combining the probabilities, after which major peaks and troughs in the trends are assumed to reflect changes in human demographics. Using 14C dates from Buchanan et al. (2008), we analyzed multiple regions, including the Southeast and Great Plains. Contrary to Buchanan et al., we found an abrupt, statistically significant decline at 12.9 ka, followed 200 to 900 years later by a rebound in the number of

Reptiles and amphibians

Science.gov (United States)

Lovich, Jeffrey E.; Ennen, Joshua R.; Perrow, Martin

2017-01-01

Summary – We reviewed all the peer-reviewed scientific publications we could find on the known and potential effects of wind farm development, operation, maintenance, and decommissioning on reptiles and amphibians (collectively herpetofauna) worldwide. Both groups are declining globally due to a multitude of threats including energy development. Effect studies were limited to the long-term research by the authors on Agassiz’s Desert Tortoise ecology and behavior at single operational wind farm in California, US and an analysis of the effects of wind farm installation on species richness of vertebrates including reptiles and amphibians in northwestern Portugal. Research on Agassiz’s Desert Tortoise found few demonstrable differences in biological parameters between populations in the wind farm and those in more natural habitats. High reproductive output is due to the regional climate and not to the presence or operation of the wind farm. Site operations have resulted in death and injury to a small number of adult tortoises and over the long-term tortoises now appear to avoid the areas of greatest turbine concentration. Research in Portugal using models and simulations based on empirical data show that vertebrate species richness (including herpetofauna) decreased by almost 20% after the installation of only two large monopole turbines per 250 x 250 m plot. Knowledge of the known responses of herpetofauna to various disturbances allows identification of potential impacts from construction material acquisition in offsite areas, mortality and stress due to impacts of roads and related infrastructure, destruction and modification of habitat, habitat fragmentation and barriers to gene flow, noise, vibration, electromagnetic field generation, heat from buried high voltage transmission lines, alteration of local and regional climate, predator attraction, and increased risk of fire. Research on herpetofauna lags far behind what is needed and, in particular, before

Predicting breeding habitat for amphibians: a spatiotemporal analysis across Yellowstone National Park.

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Bartelt, Paul E; Gallant, Alisa L; Klaver, Robert W; Wright, Chris K; Patla, Debra A; Peterson, Charles R

2011-10-01

The ability to predict amphibian breeding across landscapes is important for informing land management decisions and helping biologists better understand and remediate factors contributing to declines in amphibian populations. We built geospatial models of likely breeding habitats for each of four amphibian species that breed in Yellowstone National Park (YNP). We used field data collected in 2000-2002 from 497 sites among 16 basins and predictor variables from geospatial models produced from remotely sensed data (e.g., digital elevation model, complex topographic index, landform data, wetland probability, and vegetative cover). Except for 31 sites in one basin that were surveyed in both 2000 and 2002, all sites were surveyed once. We used polytomous regression to build statistical models for each species of amphibian from (1) field survey site data only, (2) field data combined with data from geospatial models, and (3) data from geospatial models only. Based on measures of receiver operating characteristic (ROC) scores, models of the second type best explained likely breeding habitat because they contained the most information (ROC values ranged from 0.70 to 0.88). However, models of the third type could be applied to the entire YNP landscape and produced maps that could be verified with reserve field data. Accuracy rates for models built for single years were highly variable, ranging from 0.30 to 0.78. Accuracy rates for models built with data combined from multiple years were higher and less variable, ranging from 0.60 to 0.80. Combining results from the geospatial multiyear models yielded maps of "core" breeding areas (areas with high probability values for all three years) surrounded by areas that scored high for only one or two years, providing an estimate of variability among years. Such information can highlight landscape options for amphibian conservation. For example, our models identify alternative areas that could be protected for each species

Phylogenetically-informed priorities for amphibian conservation.

Science.gov (United States)

Isaac, Nick J B; Redding, David W; Meredith, Helen M; Safi, Kamran

2012-01-01

The amphibian decline and extinction crisis demands urgent action to prevent further large numbers of species extinctions. Lists of priority species for conservation, based on a combination of species' threat status and unique contribution to phylogenetic diversity, are one tool for the direction and catalyzation of conservation action. We describe the construction of a near-complete species-level phylogeny of 5713 amphibian species, which we use to create a list of evolutionarily distinct and globally endangered species (EDGE list) for the entire class Amphibia. We present sensitivity analyses to test the robustness of our priority list to uncertainty in species' phylogenetic position and threat status. We find that both sources of uncertainty have only minor impacts on our 'top 100' list of priority species, indicating the robustness of the approach. By contrast, our analyses suggest that a large number of Data Deficient species are likely to be high priorities for conservation action from the perspective of their contribution to the evolutionary history.

Phylogenetically-informed priorities for amphibian conservation.

Directory of Open Access Journals (Sweden)

Nick J B Isaac

Full Text Available The amphibian decline and extinction crisis demands urgent action to prevent further large numbers of species extinctions. Lists of priority species for conservation, based on a combination of species' threat status and unique contribution to phylogenetic diversity, are one tool for the direction and catalyzation of conservation action. We describe the construction of a near-complete species-level phylogeny of 5713 amphibian species, which we use to create a list of evolutionarily distinct and globally endangered species (EDGE list for the entire class Amphibia. We present sensitivity analyses to test the robustness of our priority list to uncertainty in species' phylogenetic position and threat status. We find that both sources of uncertainty have only minor impacts on our 'top 100' list of priority species, indicating the robustness of the approach. By contrast, our analyses suggest that a large number of Data Deficient species are likely to be high priorities for conservation action from the perspective of their contribution to the evolutionary history.

The Emerging Amphibian Fungal Disease, Chytridiomycosis: A Key Example of the Global Phenomenon of Wildlife Emerging Infectious Diseases.

Science.gov (United States)

Kolby, Jonathan E; Daszak, Peter

2016-06-01

The spread of amphibian chytrid fungus, Batrachochytrium dendrobatidis, is associated with the emerging infectious wildlife disease chytridiomycosis. This fungus poses an overwhelming threat to global amphibian biodiversity and is contributing toward population declines and extinctions worldwide. Extremely low host-species specificity potentially threatens thousands of the 7,000+ amphibian species with infection, and hosts in additional classes of organisms have now also been identified, including crayfish and nematode worms.Soon after the discovery of B. dendrobatidis in 1999, it became apparent that this pathogen was already pandemic; dozens of countries and hundreds of amphibian species had already been exposed. The timeline of B. dendrobatidis's global emergence still remains a mystery, as does its point of origin. The reason why B. dendrobatidis seems to have only recently increased in virulence to catalyze this global disease event remains unknown, and despite 15 years of investigation, this wildlife pandemic continues primarily uncontrolled. Some disease treatments are effective on animals held in captivity, but there is currently no proven method to eradicate B. dendrobatidis from an affected habitat, nor have we been able to protect new regions from exposure despite knowledge of an approaching "wave" of B. dendrobatidis and ensuing disease.International spread of B. dendrobatidis is largely facilitated by the commercial trade in live amphibians. Chytridiomycosis was recently listed as a globally notifiable disease by the World Organization for Animal Health, but few countries, if any, have formally adopted recommended measures to control its spread. Wildlife diseases continue to emerge as a consequence of globalization, and greater effort is urgently needed to protect global health.

Vast underestimation of Madagascar's biodiversity evidenced by an integrative amphibian inventory.

Science.gov (United States)

Vieites, David R; Wollenberg, Katharina C; Andreone, Franco; Köhler, Jörn; Glaw, Frank; Vences, Miguel

2009-05-19

Amphibians are in decline worldwide. However, their patterns of diversity, especially in the tropics, are not well understood, mainly because of incomplete information on taxonomy and distribution. We assess morphological, bioacoustic, and genetic variation of Madagascar's amphibians, one of the first near-complete taxon samplings from a biodiversity hotspot. Based on DNA sequences of 2,850 specimens sampled from over 170 localities, our analyses reveal an extreme proportion of amphibian diversity, projecting an almost 2-fold increase in species numbers from the currently described 244 species to a minimum of 373 and up to 465. This diversity is widespread geographically and across most major phylogenetic lineages except in a few previously well-studied genera, and is not restricted to morphologically cryptic clades. We classify the genealogical lineages in confirmed and unconfirmed candidate species or deeply divergent conspecific lineages based on concordance of genetic divergences with other characters. This integrative approach may be widely applicable to improve estimates of organismal diversity. Our results suggest that in Madagascar the spatial pattern of amphibian richness and endemism must be revisited, and current habitat destruction may be affecting more species than previously thought, in amphibians as well as in other animal groups. This case study suggests that worldwide tropical amphibian diversity is probably underestimated at an unprecedented level and stresses the need for integrated taxonomic surveys as a basis for prioritizing conservation efforts within biodiversity hotspots.

Dropping dead: causes and consequences of vulture population declines worldwide.

Science.gov (United States)

Ogada, Darcy L; Keesing, Felicia; Virani, Munir Z

2012-02-01

Vultures are nature's most successful scavengers, and they provide an array of ecological, economic, and cultural services. As the only known obligate scavengers, vultures are uniquely adapted to a scavenging lifestyle. Vultures' unique adaptations include soaring flight, keen eyesight, and extremely low pH levels in their stomachs. Presently, 14 of 23 (61%) vulture species worldwide are threatened with extinction, and the most rapid declines have occurred in the vulture-rich regions of Asia and Africa. The reasons for the population declines are varied, but poisoning or human persecution, or both, feature in the list of nearly every declining species. Deliberate poisoning of carnivores is likely the most widespread cause of vulture poisoning. In Asia, Gyps vultures have declined by >95% due to poisoning by the veterinary drug diclofenac, which was banned by regional governments in 2006. Human persecution of vultures has occurred for centuries, and shooting and deliberate poisoning are the most widely practiced activities. Ecological consequences of vulture declines include changes in community composition of scavengers at carcasses and an increased potential for disease transmission between mammalian scavengers at carcasses. There have been cultural and economic costs of vulture declines as well, particularly in Asia. In the wake of catastrophic vulture declines in Asia, regional governments, the international scientific and donor communities, and the media have given the crisis substantial attention. Even though the Asian vulture crisis focused attention on the plight of vultures worldwide, the situation for African vultures has received relatively little attention especially given the similar levels of population decline. While the Asian crisis has been largely linked to poisoning by diclofenac, vulture population declines in Africa have numerous causes, which have made conserving existing populations more difficult. And in Africa there has been little

Ecopathology of Ranaviruses Infecting Amphibians

Directory of Open Access Journals (Sweden)

Andrew Storfer

2011-11-01

Full Text Available Ranaviruses are capable of infecting amphibians from at least 14 families and over 70 individual species. Ranaviruses infect multiple cell types, often culminating in organ necrosis and massive hemorrhaging. Subclinical infections have been documented, although their role in ranavirus persistence and emergence remains unclear. Water is an effective transmission medium for ranaviruses, and survival outside the host may be for significant duration. In aquatic communities, amphibians, reptiles and fish may serve as reservoirs. Controlled studies have shown that susceptibility to ranavirus infection and disease varies among amphibian species and developmental stages, and likely is impacted by host-pathogen coevolution, as well as, exogenous environmental factors. Field studies have demonstrated that the likelihood of epizootics is increased in areas of cattle grazing, where aquatic vegetation is sparse and water quality is poor. Translocation of infected amphibians through commercial trade (e.g., food, fish bait, pet industry contributes to the spread of ranaviruses. Such introductions may be of particular concern, as several studies report that ranaviruses isolated from ranaculture, aquaculture, and bait facilities have greater virulence (i.e., ability to cause disease than wild-type isolates. Future investigations should focus on the genetic basis for pathogen virulence and host susceptibility, ecological and anthropogenic mechanisms contributing to emergence, and vaccine development for use in captive populations and species reintroduction programs.

Culture Media and Individual Hosts Affect the Recovery of Culturable Bacterial Diversity from Amphibian Skin.

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Medina, Daniel; Walke, Jenifer B; Gajewski, Zachary; Becker, Matthew H; Swartwout, Meredith C; Belden, Lisa K

2017-01-01

One current challenge in microbial ecology is elucidating the functional roles of the large diversity of free-living and host-associated bacteria identified by culture-independent molecular methods. Importantly, the characterization of this immense bacterial diversity will likely require merging data from culture-independent approaches with work on bacterial isolates in culture. Amphibian skin bacterial communities have become a recent focus of work in host-associated microbial systems due to the potential role of these skin bacteria in host defense against the pathogenic fungus Batrachochytrium dendrobatidis (Bd), which is associated with global amphibian population declines and extinctions. As there is evidence that some skin bacteria may inhibit growth of Bd and prevent infection in some cases, there is interest in using these bacteria as probiotic therapy for conservation of at-risk amphibians. In this study, we used skin swabs from American toads ( Anaxyrus americanus ) to: (1) assess the diversity and community structure of culturable amphibian skin bacteria grown on high and low nutrient culture media, (2) determine which culture media recover the highest proportion of the total skin bacterial community of individual toads relative to culture-independent data, and (3) assess whether the plated communities from the distinct media types vary in their ability to inhibit Bd growth in in-vitro assays. Overall, we found that culture media with low nutrient concentrations facilitated the growth of more diverse bacterial taxa and grew distinct communities relative to media with higher nutrient concentrations. Use of low nutrient media also resulted in culturing proportionally more of the bacterial diversity on individual toads relative to the overall community defined using culture-independent methods. However, while there were differences in diversity among media types, the variation among individual hosts was greater than variation among media types, suggesting

The effects of declining population growth on the demand for housing.

Science.gov (United States)

Thomas C. Marcin

1974-01-01

Declining population growth and unprecedented changes in the age structure of the population in the next several decades will profoundly affect housing demand in the next 50 years. A decline in housing demand and substantial change in the type of housing in demand are likely to occur by 1990.

Impacts of road deicing salt on the demography of vernal pool-breeding amphibians.

Science.gov (United States)

Karraker, Nancy E; Gibbs, James P; Vonesh, James R

2008-04-01

Deicing agents, primarily road salt, are applied to roads in 26 states in the United States and in a number of European countries, yet the scale of impacts of road salt on aquatic organisms remains largely under-studied. The issue is germane to amphibian conservation because both adult and larval amphibians are known to be particularly sensitive to changes in their osmolar environments. In this study, we combined survey, experimental, and demographic modeling approaches to evaluate the possible effects of road salt on two common vernal-pond-breeding amphibian species, the spotted salamander (Ambystoma maculatum) and the wood frog (Rana sylvatica). We found that in the Adirondack Mountain Region of New York (USA), road salt traveled up to 172 m from the highway into wetlands. Surveys showed that egg mass densities of spotted salamanders (A. maculatum) and wood frogs (R. sylvatica) were two times higher in forest pools than roadside pools, but this pattern was better explained by road proximity than by increased salinity. Experiments demonstrated that embryonic and larval survival were reduced at moderate (500 muS) and high conductivities (3000 muS) in A. maculatum and at high conductivities in R. sylvatica. Demographic models suggest that such egg and larval stage effects of salt may have important impacts on populations near roads, particularly in the case of A. maculatum, for which salt exposure may lead to local extinction. For both species, the effect of road salt was dependent upon the strength of larval density dependence and declined rapidly with distance from the roadside, with the greatest negative effects being limited to within 50 m. Based on this evidence, we argue that efforts to protect local populations of A. maculatum and R. sylvatica in roadside wetlands should, in part, be aimed at reducing application of road salt near wetlands with high conductivity levels.

Effects of Terrestrial Buffer Zones on Amphibians on Golf Courses

Science.gov (United States)

Puglis, Holly J.; Boone, Michelle D.

2012-01-01

A major cause of amphibian declines worldwide is habitat destruction or alteration. Public green spaces, such as golf courses and parks, could serve as safe havens to curb the effects of habitat loss if managed in ways to bolster local amphibian communities. We reared larval Blanchard's cricket frogs (Acris blanchardi) and green frogs (Rana clamitans) in golf course ponds with and without 1 m terrestrial buffer zones, and released marked cricket frog metamorphs at the golf course ponds they were reared in. Larval survival of both species was affected by the presence of a buffer zone, with increased survival for cricket frogs and decreased survival for green frogs when reared in ponds with buffer zones. No marked cricket frog juveniles were recovered at any golf course pond in the following year, suggesting that most animals died or migrated. In a separate study, we released cricket frogs in a terrestrial pen and allowed them to choose between mown and unmown grass. Cricket frogs had a greater probability of using unmown versus mown grass. Our results suggest that incorporating buffer zones around ponds can offer suitable habitat for some amphibian species and can improve the quality of the aquatic environment for some sensitive local amphibians. PMID:22761833

Factors related to the distribution and prevalence of the fungal pathogen Batrachochytrium dentrobatidis in Rana cascadae and other amphibians in the Klamath Mountains

Science.gov (United States)

Jonah Piovia-Scott; Karen L. Pope; Sharon P. Lawler; Esther M. Cole; Janet E. Foley

2011-01-01

The fungal pathogen Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis, has been associated with declines and extinctions of montane amphibians worldwide. To gain insight into factors affecting its distribution and prevalence we focus on the amphibian community of the Klamath Mountains in northwest...

Monarch butterfly population decline in North America: identifying the threatening processes

Science.gov (United States)

Thogmartin, Wayne E.; Wiederholt, Ruscena; Oberhauser, Karen; Drum, Ryan G.; Diffendorfer, Jay E.; Altizer, Sonia; Taylor, Orley R.; Pleasants, John M.; Semmens, Darius J.; Semmens, Brice X.; Erickson, Richard A.; Libby, Kaitlin; Lopez-Hoffman, Laura

2017-01-01

The monarch butterfly (Danaus plexippus) population in North America has sharply declined over the last two decades. Despite rising concern over the monarch butterfly's status, no comprehensive study of the factors driving this decline has been conducted. Using partial least-squares regressions and time-series analysis, we investigated climatic and habitat-related factors influencing monarch population size from 1993 to 2014. Potential threats included climatic factors, habitat loss (milkweed and overwinter forest), disease and agricultural insecticide use (neonicotinoids). While climatic factors, principally breeding season temperature, were important determinants of annual variation in abundance, our results indicated strong negative relationships between population size and habitat loss variables, principally glyphosate use, but also weaker negative effects from the loss of overwinter forest and breeding season use of neonicotinoids. Further declines in population size because of glyphosate application are not expected. Thus, if remaining threats to habitat are mitigated we expect climate-induced stochastic variation of the eastern migratory population of monarch butterfly around a relatively stationary population size.

Toxicity of a glufosinate- and several glyphosate-based herbicides to juvenile amphibians from the Southern High Plains, USA.

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Dinehart, Simon K; Smith, Loren M; McMurry, Scott T; Anderson, Todd A; Smith, Philip N; Haukos, David A

2009-01-15

Pesticide toxicity is often proposed as a contributing factor to the world-wide decline of amphibian populations. We assessed acute toxicity (48 h) of a glufosinate-based herbicide (Ignite 280 SL) and several glyphosate-based herbicide formulations (Roundup WeatherMAX, Roundup Weed and Grass Killer Super Concentrate, Roundup Weed and Grass Killer Ready-To-Use Plus on two species of amphibians housed on soil or moist paper towels. Survival of juvenile Great Plains toads (Bufo cognatus) and New Mexico spadefoots (Spea multiplicata) was reduced by exposure to Roundup Weed and Grass Killer Ready-To-Use Plus on both substrates. Great Plains toad survival was also reduced by exposure to Roundup Weed and Grass Killer Super Concentrate on paper towels. New Mexico spadefoot and Great Plains toad survival was not affected by exposure to the two agricultural herbicides (Roundup WeatherMAX and Ignite 280 SL) on either substrate, suggesting that these herbicides likely do not pose an immediate risk to these species under field conditions.

Diversity and dynamics of amphibians in floodplain ecosystems of the Samara river

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O. V. Zhukov

2015-04-01

Full Text Available High emphasis is placed on amphibian importance as a buffer system, which has inhibiting effect on technogenic transformation of biogeocoenoses. Issues of the animals’ use in biological restoration, ecological rehabilitation of technogenic landscapes and in bioindication of environmental conditions are covered. Сhange in any component of the ecosystem leads to changing of the whole ecosystem. Anuran amphibians are extremely vulnerable to harmful effects of many factors of natural and anthropogenic origin. That is why, the destruction of forests, draining of wetlands, global climate change, global and local environmental pollution lead to complete disappearance or drastic decrease in numbers of many species of amphibians, reduction and fragmentation of their habitats, increased diversity and overall proportion of morphological anomalies in the natural populations of this group of animals. Recent studies of morphological changes in amphibians are increasingly being used to assess the state of the natural state of their populations and quality of their environment. In the biogeocenoses which are in the conditions of transformation amphibians have a number of advantages relative to their activity, the rate of reproduction, and euribiont character. Practical recommendations on protection and enrichment of the regional herpetofauna are given. The impact of the number and species diversity of amphibians on forest ecosystems of the steppe Dnieperin various conditions is assessed. Parametric entropy factors, the coefficient of biodiversity helped to identify the dominant species of amphibians. Taking into account the influence of predictors, there is the possibility to determine the number and species diversity of amphibians in the conditions of floodplain lime-ash forest. As a result of recording, the following species were caught: Pelobates fuscus (Laurenti, 1768, Rana arvalis Nilsson, 1842, Bufo bufo (Linnaeus, 1758, Bombina bombina (Linnaeus, 1758

Understanding of the impact of chemicals on amphibians: a meta-analytic review.

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Egea-Serrano, Andrés; Relyea, Rick A; Tejedo, Miguel; Torralva, Mar

2012-07-01

Many studies have assessed the impact of different pollutants on amphibians across a variety of experimental venues (laboratory, mesocosm, and enclosure conditions). Past reviews, using vote-counting methods, have described pollution as one of the major threats faced by amphibians. However, vote-counting methods lack strong statistical power, do not permit one to determine the magnitudes of effects, and do not compare responses among predefined groups. To address these challenges, we conducted a meta-analysis of experimental studies that measured the effects of different chemical pollutants (nitrogenous and phosphorous compounds, pesticides, road deicers, heavy metals, and other wastewater contaminants) at environmentally relevant concentrations on amphibian survival, mass, time to hatching, time to metamorphosis, and frequency of abnormalities. The overall effect size of pollutant exposure was a medium decrease in amphibian survival and mass and a large increase in abnormality frequency. This translates to a 14.3% decrease in survival, a 7.5% decrease in mass, and a 535% increase in abnormality frequency across all studies. In contrast, we found no overall effect of pollutants on time to hatching and time to metamorphosis. We also found that effect sizes differed among experimental venues and among types of pollutants, but we only detected weak differences among amphibian families. These results suggest that variation in sensitivity to contaminants is generally independent of phylogeny. Some publication bias (i.e., selective reporting) was detected, but only for mass and the interaction effect size among stressors. We conclude that the overall impact of pollution on amphibians is moderately to largely negative. This implies that pollutants at environmentally relevant concentrations pose an important threat to amphibians and may play a role in their present global decline.

Towards gene banking amphibian maternal germ lines: short-term incubation, cryoprotectant tolerance and cryopreservation of embryonic cells of the frog, Limnodynastes peronii.

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Lawson, Bianca; Clulow, Simon; Mahony, Michael J; Clulow, John

2013-01-01

Gene banking is arguably the best method available to prevent the loss of genetic diversity caused by declines in wild populations, when the causes of decline cannot be halted or reversed. For one of the most impacted vertebrate groups, the amphibians, gene banking technologies have advanced considerably, and gametes from the male line can be banked successfully for many species. However, cryopreserving the female germ line remains challenging, with attempts at cryopreserving oocytes unsuccessful due to their large size and yolk content. One possible solution is to target cryopreservation of early embryos that contain the maternal germ line, but consist of smaller cells. Here, we investigate the short term incubation, cryoprotectant tolerance, and cryopreservation of dissociated early embryonic cells from gastrulae and neurulae of the Striped Marsh Frog, Limnodynastes peronii. Embryos were dissociated and cells were incubated for up to 24 hours in various media. Viability of both gastrula and neurula cells remained high (means up to 40-60%) over 24 hours of incubation in all media, although viability was maintained at a higher level in Ca(2+)-free Simplified Amphibian Ringer; low speed centrifugation did not reduce cell viability. Tolerance of dissociated embryonic cells was tested for two cryoprotectants, glycerol and dimethyl sulphoxide; dissociated cells of both gastrulae and neurulae were highly tolerant to both-indeed, cell viability over 24 hours was higher in media containing low-to-medium concentrations than in equivalent cryoprotectant-free media. Viability over 24 hours was lower in concentrations of cryoprotectant higher than 10%. Live cells were recovered following cryopreservation of both gastrula and neurula cells, but only at low rates. Optimal cryodiluents were identified for gastrula and neurula cells. This is the first report of a slow cooling protocol for cryopreservation of amphibian embryonic cells, and sets future research directions for

Towards gene banking amphibian maternal germ lines: short-term incubation, cryoprotectant tolerance and cryopreservation of embryonic cells of the frog, Limnodynastes peronii.

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Bianca Lawson

Full Text Available Gene banking is arguably the best method available to prevent the loss of genetic diversity caused by declines in wild populations, when the causes of decline cannot be halted or reversed. For one of the most impacted vertebrate groups, the amphibians, gene banking technologies have advanced considerably, and gametes from the male line can be banked successfully for many species. However, cryopreserving the female germ line remains challenging, with attempts at cryopreserving oocytes unsuccessful due to their large size and yolk content. One possible solution is to target cryopreservation of early embryos that contain the maternal germ line, but consist of smaller cells. Here, we investigate the short term incubation, cryoprotectant tolerance, and cryopreservation of dissociated early embryonic cells from gastrulae and neurulae of the Striped Marsh Frog, Limnodynastes peronii. Embryos were dissociated and cells were incubated for up to 24 hours in various media. Viability of both gastrula and neurula cells remained high (means up to 40-60% over 24 hours of incubation in all media, although viability was maintained at a higher level in Ca(2+-free Simplified Amphibian Ringer; low speed centrifugation did not reduce cell viability. Tolerance of dissociated embryonic cells was tested for two cryoprotectants, glycerol and dimethyl sulphoxide; dissociated cells of both gastrulae and neurulae were highly tolerant to both-indeed, cell viability over 24 hours was higher in media containing low-to-medium concentrations than in equivalent cryoprotectant-free media. Viability over 24 hours was lower in concentrations of cryoprotectant higher than 10%. Live cells were recovered following cryopreservation of both gastrula and neurula cells, but only at low rates. Optimal cryodiluents were identified for gastrula and neurula cells. This is the first report of a slow cooling protocol for cryopreservation of amphibian embryonic cells, and sets future research

Identifying species conservation strategies to reduce disease-associated declines

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Gerber, Brian D.; Converse, Sarah J.; Muths, Erin L.; Crockett, Harry J.; Mosher, Brittany A.; Bailey, Larissa L.

2018-01-01

Emerging infectious diseases (EIDs) are a salient threat to many animal taxa, causing local and global extinctions, altering communities and ecosystem function. The EID chytridiomycosis is a prominent driver of amphibian declines, which is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). To guide conservation policy, we developed a predictive decision-analytic model that combines empirical knowledge of host-pathogen metapopulation dynamics with expert judgment regarding effects of management actions, to select from potential conservation strategies. We apply our approach to a boreal toad (Anaxyrus boreas boreas) and Bd system, identifying optimal strategies that balance tradeoffs in maximizing toad population persistence and landscape-level distribution, while considering costs. The most robust strategy is expected to reduce the decline of toad breeding sites from 53% to 21% over 50 years. Our findings are incorporated into management policy to guide conservation planning. Our online modeling application provides a template for managers of other systems challenged by EIDs.

Joint effects of pesticides and ultraviolet-B radiation on amphibian larvae

International Nuclear Information System (INIS)

Yu, Shuangying; Wages, Mike; Willming, Morgan; Cobb, George P.; Maul, Jonathan D.

2015-01-01

A combination of multiple stressors may be linked to global amphibian declines. Of these, pesticides and UVB radiation co-exposures were examined on the African clawed frog (Xenopus laevis) to provide information that may be useful for amphibian conservation. The independent action model and inferential statistics were used to examine interactions between pesticides (malathion, endosulfan, α-cypermethrin, or chlorothalonil) and environmentally relevant UVB exposures. UVB radiation alone caused 35–68% mortality and nearly 100% of malformations. Pesticides and UVB had additive effects on larval mortality; however, several non-additive effects (antagonistic and synergistic interactions) were observed for total body length. Insecticides mainly affected axial development, whereas UVB radiation caused high incidence of edema, gut malformations, and abnormal tail tips. These results suggest that sublethal developmental endpoints were more sensitive for detecting joint effects. This work has implications for amphibian risk assessments for ecosystems where pesticides and high UVB radiation may co-occur. - Highlights: • Interactive effects of UVB radiation-pesticide co-exposures were examined in frogs. • UVB radiation alone caused 35–68% mortality and nearly 100% of malformations. • Pesticides and UVB had additive effects on larval mortality. • Several non-additive effects were observed for total body length. • Amphibian risk assessments should consider UVB radiation exposure as a co-stressor. - Possible interactions between pesticides and UVB radiation support the idea that amphibian risk assessments should consider these co-stressors when high UVB radiation exposure is high.

Investigating Rates of Hunting and Survival in Declining European Lapwing Populations.

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Guillaume Souchay

Full Text Available Understanding effects of harvest on population dynamics is of major interest, especially for declining species. European lapwing Vanellus vanellus populations increased from the 1960s until the 1980s and declined strongly thereafter. About 400,000 lapwings are harvested annually and it is thus of high conservation relevance to assess whether hunting was a main cause for the observed changes in lapwing population trends. We developed a multi-event cause-specific mortality model which we applied to a long-term ring-recovery data set (1960-2010 of > 360,000 records to estimate survival and cause-specific mortalities. We found no temporal change in survival over the last 50 years for first-year (FY and older birds (after first-year; AFY originating from different ringing areas. Mean survival was high, around 0.60 and 0.80 for FY and AFY individuals, respectively. The proportion of total mortality due to hunting was <0.10 over the study period and the estimated proportion of harvested individuals (kill rate was <0.05 in each year. Our result of constant survival indicates that demographic processes other than survival were responsible for the pronounced change in lapwing population trends in the 1980s. Our findings lend support to the hypothesis that hunting was not a significant contributor to the large-scale decline of lapwing populations. To halt the ongoing decline of European lapwing populations management should focus on life history stages other than survival (e.g. productivity. Further analyses are required to investigate the contribution of other demographic rates to the decline of lapwings and to identify the most efficient conservation actions.

Acute oral toxicity of chemicals in terrestrial life stages of amphibians: Comparisons to birds and mammals.

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Crane, Mark; Finnegan, Meaghean; Weltje, Lennart; Kosmala-Grzechnik, Sylwia; Gross, Melanie; Wheeler, James R

2016-10-01

Amphibians are currently the most threatened and rapidly declining group of vertebrates and this has raised concerns about their potential sensitivity and exposure to plant protection products and other chemicals. Current environmental risk assessment procedures rely on surrogate species (e.g. fish and birds) to cover the risk to aquatic and terrestrial life stages of amphibians, respectively. Whilst a recent meta-analysis has shown that in most cases amphibian aquatic life stages are less sensitive to chemicals than fish, little research has been conducted on the comparative sensitivity of terrestrial amphibian life stages. Therefore, in this paper we address the questions "What is the relative sensitivity of terrestrial amphibian life stages to acute chemical oral exposure when compared with mammals and birds?" and "Are there correlations between oral toxicity data for amphibians and data for mammals or birds?" Identifying a relationship between these data may help to avoid additional vertebrate testing. Acute oral amphibian toxicity data collected from the scientific literature and ecotoxicological databases were compared with toxicity data for mammals and birds. Toxicity data for terrestrial amphibian life stages are generally sparse, as noted in previous reviews. Single-dose oral toxicity data for terrestrial amphibian life stages were available for 26 chemicals and these were positively correlated with LD50 values for mammals, while no correlation was found for birds. Further, the data suggest that oral toxicity to terrestrial amphibian life stages is similar to or lower than that for mammals and birds, with a few exceptions. Thus, mammals or birds are considered adequate toxicity surrogates for use in the assessment of the oral exposure route in amphibians. However, there is a need for further data on a wider range of chemicals to explore the wider applicability of the current analyses and recommendations. Copyright © 2016 Elsevier Inc. All rights reserved.

Roles of patch characteristics, drought frequency, and restoration in long-term trends of a widespread amphibian.

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Hossack, Blake R; Adams, Michael J; Pearl, Christopher A; Wilson, Kristine W; Bull, Evelyn L; Lohr, Kristin; Patla, Debra; Pilliod, David S; Jones, Jason M; Wheeler, Kevin K; McKay, Samuel P; Corn, Paul Stephen

2013-12-01

Despite the high profile of amphibian declines and the increasing threat of drought and fragmentation to aquatic ecosystems, few studies have examined long-term rates of change for a single species across a large geographic area. We analyzed growth in annual egg-mass counts of the Columbia spotted frog (Rana luteiventris) across the northwestern United States, an area encompassing 3 genetic clades. On the basis of data collected by multiple partners from 98 water bodies between 1991 and 2011, we used state-space and linear-regression models to measure effects of patch characteristics, frequency of summer drought, and wetland restoration on population growth. Abundance increased in the 2 clades with greatest decline history, but declined where populations are considered most secure. Population growth was negatively associated with temporary hydroperiods and landscape modification (measured by the human footprint index), but was similar in modified and natural water bodies. The effect of drought was mediated by the size of the water body: populations in large water bodies maintained positive growth despite drought, whereas drought magnified declines in small water bodies. Rapid growth in restored wetlands in areas of historical population declines provided strong evidence of successful management. Our results highlight the importance of maintaining large areas of habitat and underscore the greater vulnerability of small areas of habitat to environmental stochasticity. Similar long-term growth rates in modified and natural water bodies and rapid, positive responses to restoration suggest pond construction and other forms of management can effectively increase population growth. These tools are likely to become increasingly important to mitigate effects of increased drought expected from global climate change. Papeles de las Características del Fragmento, Frecuencia de Sequía y Restauración en las Tendencias a Largo Plazo de un Anfibio Ampliamente Distribuido

Efficacy of SYBR 14/propidium iodide viability stain for the amphibian chytrid fungus Batrachochytrium dendrobatidis.

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Stockwell, M P; Clulow, J; Mahony, M J

2010-01-25

The amphibian chytrid fungus Batrachochytrium dendrobatidis is a recently described pathogen that has been implicated as a causal agent in the global decline in amphibians. Research into its biology and epidemiology has frequently involved in vitro experimentation. However, this research is currently limited by the inability to differentiate between viable and inviable zoospores. Stains are frequently used to determine cell viability, and this study tested a 2-colour fluorescence assay for the detection and quantification of viable B. dendrobatidis zoospores. The results show that the nucleic acid stains SYBR 14 and propidium iodide are effective in distinguishing live from dead zoospores, and a protocol has been optimized for their use. This viability assay provides an efficient and reliable tool that will have applications in B. dendrobatidis challenge and amphibian exposure experiments.

Physical habitat and its alteration: A common ground for exposure of amphibians to environmental stressors

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Bishop, Christine A.; Cunnington, David C.; Fellers, Gary M.; Gibbs, James P.; Pauli, Bruce D.; Rothermel, Betsie B.; Linder, Greg L.; Krest, Sherry K.; Sparling, Donald W.

2003-01-01

Amphibians as a class of vertebrates have persisted for hundreds of millions of years (Stebbins and Cohen 1995), but they are currently threatened by a variety of stressors, many resulting from human-related alterations of the environment. Most species of amphibians live closely associated with moist environments throughout their life and have evolved specialized adaptations that conserve water and reduce desiccation (Stebbins and Cohen 1995; Henry 2000; Chapter 2A). Amphibians are ectotherms, so their body temperatures fluctuate with the local environment. Latitude, elevation, and habitat affect environmental temperature and have a strong influence on amphibian distributions. Despite these physiological and habitat constraints, the 4750 species of amphibians in the world today have exploited a wide variety of habitats that range from dry deserts to tropical rain forests and from sea level to elevations above 4000 m (McDairmid and Mitchell 2000).The direct loss of suitable habitat has had a profound effect on amphibian populations (Johnson 1992), as it has on nearly all species of wildlife. In the U.S., 53% of wetlands have been lost to human development in the last 200 years (Dahl 1990). Similar loss of wetlands has occurred throughout much of the world, especially in developing countries (Miller 1993). In many regions, deforestation has reduced or eliminated suitable terrestrial habitats, and this may prove to be the largest global threat to amphibian populations (Johnson 1992). Eight thousand years ago, forests covered approximately 40% of the world’s land (6 billion hectares), but by 1997, the world’s forests had been reduced to 3.5 billion hectares, a 42% loss worldwide (CIDA 2001). The effect of habitat loss is generally both obvious and predictable; with increasing restriction of suitable habitat, amphibian populations will probably not survive. The anthropogenic effects on the quality of the habitat that remains are often less obvious.

Amphibians of Olympic National Park

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,

2000-01-01

Amphibians evolved from fishes about 360 million years ago and were the first vertebrates adapted to life on land. The word amphibian means "double life." It refers to the life history of many amphibians, which spend part of their life in water and part on land. There are three major groups of amphibians: salamanders, frogs, and toads, and caecilians. Salamanders, frogs, and toads can be found in Olympic National Park (ONP), but caecilians live only in tropical regions. Many amphibians are generalist predators, eating almost any prey they can fit into their mouths.

Declines in low-elevation subalpine tree populations outpace growth in high-elevation populations with warming

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Conlisk, Erin; Castanha, Cristina; Germino, Matthew J.; Veblen, Thomas T; Smith, Jeremy M.; Kueppers, Lara M.

2017-01-01

Species distribution shifts in response to climate change require that recruitment increase beyond current range boundaries. For trees with long life spans, the importance of climate-sensitive seedling establishment to the pace of range shifts has not been demonstrated quantitatively.Using spatially explicit, stochastic population models combined with data from long-term forest surveys, we explored whether the climate-sensitivity of recruitment observed in climate manipulation experiments was sufficient to alter populations and elevation ranges of two widely distributed, high-elevation North American conifers.Empirically observed, warming-driven declines in recruitment led to rapid modelled population declines at the low-elevation, ‘warm edge’ of subalpine forest and slow emergence of populations beyond the high-elevation, ‘cool edge’. Because population declines in the forest occurred much faster than population emergence in the alpine, we observed range contraction for both species. For Engelmann spruce, this contraction was permanent over the modelled time horizon, even in the presence of increased moisture. For limber pine, lower sensitivity to warming may facilitate persistence at low elevations – especially in the presence of increased moisture – and rapid establishment above tree line, and, ultimately, expansion into the alpine.Synthesis. Assuming 21st century warming and no additional moisture, population dynamics in high-elevation forests led to transient range contractions for limber pine and potentially permanent range contractions for Engelmann spruce. Thus, limitations to seedling recruitment with warming can constrain the pace of subalpine tree range shifts.

Effects of road salt on larval amphibian susceptibility to parasitism through behavior and immunocompetence.

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Milotic, Dino; Milotic, Marin; Koprivnikar, Janet

2017-08-01

Large quantities of road salts are used for de-icing in temperate climates but often leach into aquatic ecosystems where they can cause harm to inhabitants, including reduced growth and survival. However, the implications of road salt exposure for aquatic animal susceptibility to pathogens and parasites have not yet been examined even though infectious diseases can significantly contribute to wildlife population declines. Through a field survey, we found a range of NaCl concentrations (50-560mg/L) in ponds known to contain larval amphibians, with lower levels found in sites close to gravel- rather than hard-surfaced roads. We then investigated how chronic exposure to environmentally-realistic levels of road salt (up to 1140mg/L) affected susceptibility to infection by trematode parasites (helminths) in larval stages of two amphibian species (Lithobates sylvaticus - wood frogs, and L. pipiens - northern leopard frogs) by considering effects on host anti-parasite behavior and white blood cell profiles. Wood frogs exposed to road salt had higher parasite loads, and also exhibited reduced anti-parasite behavior in these conditions. In contrast, infection intensity in northern leopard frogs had a non-monotonic response to road salts even though lymphocytes were only elevated at the highest concentration. Our results indicate the potential for chronic road salt exposure to affect larval amphibian susceptibility to pathogenic parasites through alterations of behavior and immunocompetence, with further studies needed at higher concentrations, as well as that of road salts on free-living parasite infectious stages. Copyright © 2017 Elsevier B.V. All rights reserved.

Reduced itraconazole concentration and durations are successful in treating Batrachochytrium dendrobatidis infection in amphibians.

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Brannelly, Laura A

2014-03-14

Amphibians are experiencing the greatest decline of any vertebrate class and a leading cause of these declines is a fungal pathogen, Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis. Captive assurance colonies are important worldwide for threatened amphibian species and may be the only lifeline for those in critical threat of extinction. Maintaining disease free colonies is a priority of captive managers, yet safe and effective treatments for all species and across life stages have not been identified. The most widely used chemotherapeutic treatment is itraconazole, although the dosage commonly used can be harmful to some individuals and species. We performed a clinical treatment trial to assess whether a lower and safer but effective dose of itraconazole could be found to cure Bd infections. We found that by reducing the treatment concentration from 0.01-0.0025% and reducing the treatment duration from 11-6 days of 5 min baths, frogs could be cured of Bd infection with fewer side effects and less treatment-associated mortality.

Amphibians of the Simbruini Mountains (Latium, Central Italy

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Pierangelo Crucitti

2010-07-01

Full Text Available Little attention has been paid to the herpetological fauna of the Simbruini Mountains Regional Park, Latium (Central Italy. In this study, we surveyed 50 sites in the course of about ten years of field research, especially during the period 2005-2008. Nine amphibian species, four Caudata and five Anura, 60.0% out of the 15 amphibian species so far observed in Latium, were discovered in the protected area: Salamandra salamandra, Salamandrina perspicillata, Lissotriton vulgaris, Triturus carnifex, Bombina pachypus, Bufo balearicus, Bufo bufo, Rana dalmatina, Rana italica. Physiography of sites has been detailed together with potential threatening patterns. For each species the following topics have been discussed; ecology of sites, altitudinal distribution, phenology, sintopy. Salamandra salamandra and Bombina pachypus are at higher risk. The importance of the maintenance of artificial/natural water bodies for the conservation management of amphibian population of this territory is discussed.

There is no evidence for a temporal link between pathogen arrival and frog extinctions in north-eastern Australia.

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Ben L Phillips

Full Text Available Pathogen spread can cause population declines and even species extinctions. Nonetheless, in the absence of tailored monitoring schemes, documenting pathogen spread can be difficult. In the case of worldwide amphibian declines the best present understanding is that the chytrid fungus Batrachochytrium dendrobatidis (Bd has recently spread, causing amphibian declines and extinction in the process. However, good evidence demonstrating pathogen arrival followed by amphibian decline is rare, and analysis of putative evidence is often inadequate. Here we attempt to examine the relationship between Bd arrival and amphibian decline across north-eastern Australia, using sites where a wave-like pattern of amphibian decline was first noticed and at which intensive research has since been conducted. We develop an analytical framework that allows rigorous estimation of pathogen arrival date, which can then be used to test for a correlation between the time of pathogen arrival and amphibian decline across sites. Our results show that, with the current dataset, the earliest possible arrival date of Bd in north-eastern Australia is completely unresolved; Bd could have arrived immediately before sampling commenced or may have arrived thousands of years earlier, the present data simply cannot say. The currently available data are thus insufficient to assess the link between timing of pathogen arrival and population decline in this part of the world. This data insufficiency is surprising given that there have been decades of research on chytridiomycosis in Australia and that there is a general belief that the link between Bd arrival and population decline is well resolved in this region. The lack of data on Bd arrival currently acts as a major impediment to determining the role of environmental factors in driving the global amphibian declines, and should be a major focus of future research.

Death in the clouds: ranavirus associated mortality in assemblage of cloud forest amphibians in Nicaragua

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Tariq Stark

2014-06-01

Full Text Available Amphibian diseases are acknowledged as significant contributors to the decline and extinction of amphibian species. The main culprits currently considered are chytridiomycosis and Ranavirus. In Central America, highly endemic and geographical restricted terrestrial species may be at risk from these diseases. We collected 49 Agalychnis callidryas larvae, one Lithobates forrei and five unidentified larvae on the Nicaraguan Island Ometepe, all deceased, and skin samples were taken. The presence of Ranavirus was determined using PCR. Ranavirus was found involved in 41 of 55 tadpoles. Forty-one Agalychnis callidryas, one Lithobates forrei and another five unidentified anuran tadpoles.

Effects of an invasive plant on population dynamics in toads.

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Greenberg, Daniel A; Green, David M

2013-10-01

When populations decline in response to unfavorable environmental change, the dynamics of their population growth shift. In populations that normally exhibit high levels of variation in recruitment and abundance, as do many amphibians, declines may be difficult to identify from natural fluctuations in abundance. However, the onset of declines may be evident from changes in population growth rate in sufficiently long time series of population data. With data from 23 years of study of a population of Fowler's toad (Anaxyrus [ = Bufo] fowleri) at Long Point, Ontario (1989-2011), we sought to identify such a shift in dynamics. We tested for trends in abundance to detect a change point in population dynamics and then tested among competing population models to identify associated intrinsic and extrinsic factors. The most informative models of population growth included terms for toad abundance and the extent of an invasive marsh plant, the common reed (Phragmites australis), throughout the toads' marshland breeding areas. Our results showed density-dependent growth in the toad population from 1989 through 2002. After 2002, however, we found progressive population decline in the toads associated with the spread of common reeds and consequent loss of toad breeding habitat. This resulted in reduced recruitment and population growth despite the lack of significant loss of adult habitat. Our results underscore the value of using long-term time series to identify shifts in population dynamics coincident with the advent of population decline. © 2013 Society for Conservation Biology.

Population Genetic Aspects of Pollinator Decline

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Laurence Packer

2001-06-01

Full Text Available We reviewed the theory of conservation genetics, with special emphasis on the influence of haplodiploidy and other aspects of bee biology upon conservation genetic parameters. We then investigated the possibility that pollinator decline can be addressed in this way, using two meta-analytical approaches on genetic data from the Hymenoptera and the Lepidoptera. First, we compared levels of heterozygosity between the orders. As has been found previously, the haplodiploid Hymenoptera had markedly lower levels of genetic variation than the Lepidoptera. Bees had even lower levels, and bumble bees, in particular, often seemed almost monomorphic genetically. However, the statistically confounding effects of phylogeny render detailed interpretation of such data difficult. Second, we investigated patterns of gene flow among populations of these insects. Hymenoptera were far more likely to show genetic effects of population fragmentation than are Lepidoptera, even at similar geographic distances between populations. The reduced effective population sizes resulting from haplodiploidy probably contributed to this result. The proportion of species with low levels of gene flow did not vary among the different taxonomic groups within the Hymenoptera.

Changes in land use as a possible factor in Mourning Dove population decline in Central Utah

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Ostrand, William D.; Meyers, P.M.; Bissonette, J.A.; Conover, M.R.

1998-01-01

Mourning Dove (Zenaida macroura) population indices for the western United States have declined significantly since 1966. Based on data collected in 1951-1952, in Fillmore, Utah, we examined whether there had been a local decline in the dove population index since the original data were collected. We then determined whether habitat had been altered, identified which foraging habitats doves preferred, and assessed whether changes in land use could be responsible, in part, for a decline in the local population index. We found that dove population indices declined 72% and 82% from 1952-1992 and 1952-1993, respectively. The most dramatic change in habitat was an 82% decline in land devoted to dry land winter wheat production and a decline in livestock feed pens. Doves foraged primarily in harvested wheat fields, feed pens, and weedy patches. We hypothesize that a decrease in wheat availability during the spring and the consolidation of the livestock industry have contributed to a population decline of Mourning Doves in central Utah.

A conceptual model to facilitate amphibian conservation in the northern Great Plains

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Mushnet, David M.; Euliss, Ned H.; Stockwell, Craig A.

2012-01-01

As pressures on agricultural landscapes to meet worldwide resource needs increase, amphibian populations face numerous threats including habitat destruction, chemical contaminants, disease outbreaks, wetland sedimentation, and synergistic effects of these perturbations. To facilitate conservation planning, we developed a conceptual model depicting elements critical for amphibian conservation in the northern Great Plains. First, we linked upland, wetland, and landscape features to specific ecological attributes. Ecological attributes included adult survival; reproduction and survival to metamorphosis; and successful dispersal and recolonization. Second, we linked ecosystem drivers, ecosystem stressors, and ecological effects of the region to each ecological attribute. Lastly, we summarized information on these ecological attributes and the drivers, stressors, and effects that work in concert to influence the maintenance of viable and genetically diverse amphibian populations in the northern Great Plains. While our focus was on the northern Great Plains, our conceptual model can be tailored to other geographic regions and taxa.

Causes of mortality in California sea otters during periods of population growth and decline

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Estes, J.A.; Hatfield, B.B.; Ralls, K.; Ames, J.

2003-01-01

Elevated mortality appears to be the main reason for both sluggish growth and periods of decline in the threatened California sea otter population. We assessed causes of mortality from salvage records of 3,105 beach-cast carcasses recovered from 1968 through 1999, contrasting two periods of growth with two periods of decline. Overall, an estimated 40%-60% of the deaths were not recovered and 70% of the recovered carcasses died from unknown causes. Nonetheless, several common patterns were evident in the salvage records during the periods of population decline. These included greater percentages of (1) prime age animals (3-10 yr), (2) carcasses killed by great white shark attacks, (3) carcasses recovered in spring and summer, and (4) carcasses for which the cause of death was unknown. Neither sex composition nor the proportion of carcasses dying of infectious disease varied consistently between periods of population increase and decline. The population decline from 1976 to 1984 was likely due to incidental mortality in a set-net fishery, and the decline from 1995 to 1999 may be related to a developing live-fish fishery. Long-term trends unrelated to periods of growth and decline included a decrease in per capita pup production and mass/length ratios of adult carcasses over the 31-yr study. The generally high proportion of deaths from infectious disease suggests that this factor has contributed to the chronically sluggish growth rate of the California sea otter population.

Conserving Prairie Pothole Region wetlands and surrounding grasslands: evaluating effects on amphibians

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Mushet, David M.; Neau, Jordan L.

2014-01-01

The maintenance of viable and genetically diverse populations of amphibians in the Prairie Pothole Region of the United States depends on upland as well as wetland over-wintering and landscape level habitat features.Prairie pothole wetlands provide important amphibian breeding habitat while grasslands surrounding these wetlands provide foraging habitat for adults, overwintering habitat for some species, and important connectivity among breeding wetlands.Grasslands surrounding wetlands were found to be especially important for wood frogs and northern leopard frogs, while croplands dominated habitat utilized by Great Plains toads and Woodhouse’s toads.Habitat suitability mapping highlighted (1) the influence of deep-water overwintering wetlands on suitable habitat for four of five anuran species encountered; (2) the lack of overlap between areas of core habitat for both the northern leopard frog and wood frog compared to the core habitat for both toad species; and (3) the importance of conservation programs in providing grassland components of northern leopard frog and wood frog habitat.Currently, there are approximately 7.2 million acres (2.9 million hectares, ha) of habitat in the PPR identified as suitable for amphibians. WRP and CRP wetland and grassland habitats accounted for approximately 1.9 million acres (0.75 million ha) or 26 percent of this total area.Continued loss of amphibian habitat resulting from an ongoing trend of returning PPR conservation lands to crop production, will likely have significant negative effects on the region’s ability to maintain amphibian biodiversity. Conversely, increases in conservation wetlands and surrounding grasslands on the PPR landscape have great potential to positively influence the region’s amphibian populations.

Effects of atrazine on embryos, larvae, and adults of anuran amphibians.

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Allran, J W; Karasov, W H

2001-04-01

We examined the effects of atrazine (0-20 mg/L) on embryos, larvae, and adult anuran amphibian species in the laboratory. Atrazine treatments did not affect hatchability of embryos or 96-h posthatch mortality of larvae of Rana pipiens, Rana sylvatica, or Bufo americanus. Furthermore, atrazine had no effect on swimming speed (measured for R. pipiens only). However, there was a dose-dependent increase in deformed larvae of all three species with increasing atrazine concentration. In adult R. pipiens, atrazine increased buccal and thoracic ventilation, indicating respiratory distress. However, because atrazine had no affect on hemoglobin, this respiratory distress was probably not indicative of reduced oxygen-carrying capacity of the blood. Frogs exposed to the highest atrazine concentration stopped eating immediately after treatment began and did not eat during the 14-d experiment. However, no decreases in mass were measured even for frogs that were not eating, probably because of compensatory fluid gain from edema. Atrazine concentrations found to be deleterious to amphibian embryos and adults are considerably higher than concentrations currently found in surface waters in North America. Therefore, direct toxicity of atrazine is probably not a significant factor in recent amphibian declines.

Cardiac biomarkers as sensitive tools to evaluate the impact of xenobiotics on amphibians: the effects of anionic surfactant linear alkylbenzene sulfonate (LAS).

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Jones-Costa, Monica; Franco-Belussi, Lilian; Vidal, Felipe Augusto Pinto; Gongora, Nathália Penteado; Castanho, Luciano Mendes; Dos Santos Carvalho, Cleoni; Silva-Zacarin, Elaine Cristina Mathias; Abdalla, Fabio Camargo; Duarte, Iolanda Cristina Silveira; Oliveira, Classius De; de Oliveira, Cristiane Ronchi; Salla, Raquel Fernanda

2018-04-30

Amphibian populations have been experiencing a drastic decline worldwide. Aquatic contaminants are among the main factors responsible for this decline, especially in the aquatic environment. The linear alkylbenzene sulfonate (LAS) is of particular concern, since it represents 84% of the anionic surfactants' trade. In Brazil, the maximal LAS concentration allowed in fresh waters is 0.5mgL -1 , but its potential harmful effects in amphibians remain unknown. Therefore, this study aimed to analyze the effects of a sublethal concentration of LAS (0.5mgL -1 ) for 96h on sensitive cardiac biomarkers of bullfrog tadpoles, Lithobates catesbeianus (Shaw, 1802). For this, we measured the activity level (AL - % of animals), in situ heart rate (f H - bpm), relative ventricular mass (RVM - % of body mass), in vitro myocardial contractility and cardiac histology of the ventricles. Tadpoles' AL and f H decreased in LAS group. In contrast, the RVM increased, as a result of a hypertrophy of the myocardium, which was corroborated by the enlargement of the nuclear measures and the increase of myocytes' diameters. These cellular effects resulted in an elevation of the in vitro contractile force of ventricle strips. Acceleration in the contraction (TPT - ms) also occurred, although no alterations in the time to relaxation (THR -ms) were observed. Therefore, it can be concluded that even when exposed to an environmentally safe concentration, this surfactant promotes several alterations in the cardiac function of bullfrog tadpoles that can impair their development, making them more susceptible to predators and less competitive in terms of reproduction success. Thus, LAS concentrations that are considered safe by Brazilian by regulatory agencies must be revised in order to minimize a drastic impact over amphibian populations. This study demonstrates the relevance of employing cardiac biomarkers at different levels (e.g., morphological, physiological and cellular) to evaluate effects of

Life history tactics shape amphibians' demographic responses to the North Atlantic Oscillation.

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Cayuela, Hugo; Joly, Pierre; Schmidt, Benedikt R; Pichenot, Julian; Bonnaire, Eric; Priol, Pauline; Peyronel, Olivier; Laville, Mathias; Besnard, Aurélien

2017-11-01

Over the last three decades, climate abnormalities have been reported to be involved in biodiversity decline by affecting population dynamics. A growing number of studies have shown that the North Atlantic Oscillation (NAO) influences the demographic parameters of a wide range of plant and animal taxa in different ways. Life history theory could help to understand these different demographic responses to the NAO. Indeed, theory states that the impact of weather variation on a species' demographic traits should depend on its position along the fast-slow continuum. In particular, it is expected that NAO would have a higher impact on recruitment than on adult survival in slow species, while the opposite pattern is expected occur in fast species. To test these predictions, we used long-term capture-recapture datasets (more than 15,000 individuals marked from 1965 to 2015) on different surveyed populations of three amphibian species in Western Europe: Triturus cristatus, Bombina variegata, and Salamandra salamandra. Despite substantial intraspecific variation, our study revealed that these three species differ in their position on a slow-fast gradient of pace of life. Our results also suggest that the differences in life history tactics influence amphibian responses to NAO fluctuations: Adult survival was most affected by the NAO in the species with the fastest pace of life (T. cristatus), whereas recruitment was most impacted in species with a slower pace of life (B. variegata and S. salamandra). In the context of climate change, our findings suggest that the capacity of organisms to deal with future changes in NAO values could be closely linked to their position on the fast-slow continuum. © 2017 John Wiley & Sons Ltd.

Climate change and pollution speed declines in zebrafish populations.

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Brown, A Ross; Owen, Stewart F; Peters, James; Zhang, Yong; Soffker, Marta; Paull, Gregory C; Hosken, David J; Wahab, M Abdul; Tyler, Charles R

2015-03-17

Endocrine disrupting chemicals (EDCs) are potent environmental contaminants, and their effects on wildlife populations could be exacerbated by climate change, especially in species with environmental sex determination. Endangered species may be particularly at risk because inbreeding depression and stochastic fluctuations in male and female numbers are often observed in the small populations that typify these taxa. Here, we assessed the interactive effects of water temperature and EDC exposure on sexual development and population viability of inbred and outbred zebrafish (Danio rerio). Water temperatures adopted were 28 °C (current ambient mean spawning temperature) and 33 °C (projected for the year 2100). The EDC selected was clotrimazole (at 2 μg/L and 10 μg/L), a widely used antifungal chemical that inhibits a key steroidogenic enzyme [cytochrome P450(CYP19) aromatase] required for estrogen synthesis in vertebrates. Elevated water temperature and clotrimazole exposure independently induced male-skewed sex ratios, and the effects of clotrimazole were greater at the higher temperature. Male sex ratio skews also occurred for the lower clotrimazole exposure concentration at the higher water temperature in inbred fish but not in outbred fish. Population viability analysis showed that population growth rates declined sharply in response to male skews and declines for inbred populations occurred at lower male skews than for outbred populations. These results indicate that elevated temperature associated with climate change can amplify the effects of EDCs and these effects are likely to be most acute in small, inbred populations exhibiting environmental sex determination and/or differentiation.

Cryptic invasion of Northern Leopard Frogs (Rana pipiens) across phylogeographic boundaries and a dilemma for conservation of a declining amphibian

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O'Donnell, Ryan P.; Drost, Charles A.; Mock, Karen E.

2017-01-01

Anthropogenic introduction of species is a major contributor to loss of biodiversity. Translocations within the range of a species are less frequently recognized, but have the potential for negative effects as well. Genetic mixing may lead to loss of local adaptations or further decline through outbreeding depression. These cryptic invasions may be quite difficult to recognize, but genetic tools can be used to recognize and monitor such intraspecific introductions. Conversely, translocations within species can be an important conservation tool to reduce inbreeding depression and replace lost genetic diversity. Thus, cryptic invasions can be either an aid or a hindrance to conservation efforts. We tested for the presence of non-native genotypes and assessed the extent and nature of introgression in populations of Northern Leopard Frog (Rana pipiens) in the southwestern US, where populations have declined to a few remnant populations. The most abundant and diverse complex of populations in the region contained a mitochondrial haplotype that was not native to the western US, probably resulting from the introduction of released pets, laboratory animals, or release during fish stocking. These non-native haplotypes were well integrated into a large complex of ponds and lakes, contributing to high genetic diversity in this area. Logistically, the geographic extent of non-native genetic influence within this population precludes eliminating or controlling the non-native component of this population. We recommend assessing the progress and fate of the introgression over time—along with population fitness parameters—to determine whether this introduction is beneficial or detrimental to population persistence. Meanwhile, translocations from nearby locations with similar environmental conditions have the best prospects for avoiding problems with outbreeding depression in other declining populations and will also most effectively preserve regional genetic diversity.

Endemic chronic wasting disease causes mule deer population decline in Wyoming.

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Melia T DeVivo

Full Text Available Chronic wasting disease (CWD is a fatal transmissible spongiform encephalopathy affecting white-tailed deer (Odocoileus virginianus, mule deer (Odocoileus hemionus, Rocky Mountain elk (Cervus elaphus nelsoni, and moose (Alces alces shirasi in North America. In southeastern Wyoming average annual CWD prevalence in mule deer exceeds 20% and appears to contribute to regional population declines. We determined the effect of CWD on mule deer demography using age-specific, female-only, CWD transition matrix models to estimate the population growth rate (λ. Mule deer were captured from 2010-2014 in southern Converse County Wyoming, USA. Captured adult (≥ 1.5 years old deer were tested ante-mortem for CWD using tonsil biopsies and monitored using radio telemetry. Mean annual survival rates of CWD-negative and CWD-positive deer were 0.76 and 0.32, respectively. Pregnancy and fawn recruitment were not observed to be influenced by CWD. We estimated λ = 0.79, indicating an annual population decline of 21% under current CWD prevalence levels. A model derived from the demography of only CWD-negative individuals yielded; λ = 1.00, indicating a stable population if CWD were absent. These findings support CWD as a significant contributor to mule deer population decline. Chronic wasting disease is difficult or impossible to eradicate with current tools, given significant environmental contamination, and at present our best recommendation for control of this disease is to minimize spread to new areas and naïve cervid populations.

Endemic chronic wasting disease causes mule deer population decline in Wyoming

Science.gov (United States)

DeVivo, Melia T.; Edmunds, David R.; Kauffman, Matthew J.; Schumaker, Brant A.; Binfet, Justin; Kreeger, Terry J.; Richards, Bryan J.; Schatzl, Hermann M.; Cornish, Todd

2017-01-01

Chronic wasting disease (CWD) is a fatal transmissible spongiform encephalopathy affecting white-tailed deer (Odocoileus virginianus), mule deer (Odocoileus hemionus), Rocky Mountain elk (Cervus elaphus nelsoni), and moose (Alces alces shirasi) in North America. In southeastern Wyoming average annual CWD prevalence in mule deer exceeds 20% and appears to contribute to regional population declines. We determined the effect of CWD on mule deer demography using age-specific, female-only, CWD transition matrix models to estimate the population growth rate (λ). Mule deer were captured from 2010–2014 in southern Converse County Wyoming, USA. Captured adult (≥ 1.5 years old) deer were tested ante-mortem for CWD using tonsil biopsies and monitored using radio telemetry. Mean annual survival rates of CWD-negative and CWD-positive deer were 0.76 and 0.32, respectively. Pregnancy and fawn recruitment were not observed to be influenced by CWD. We estimated λ= 0.79, indicating an annual population decline of 21% under current CWD prevalence levels. A model derived from the demography of only CWD-negative individuals yielded; λ = 1.00, indicating a stable population if CWD were absent. These findings support CWD as a significant contributor to mule deer population decline. Chronic wasting disease is difficult or impossible to eradicate with current tools, given significant environmental contamination, and at present our best recommendation for control of this disease is to minimize spread to new areas and naïve cervid populations.

Trapped in the extinction vortex? Strong genetic effects in a declining vertebrate population

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Larsson Mikael

2010-02-01

Full Text Available Abstract Background Inbreeding and loss of genetic diversity are expected to increase the extinction risk of small populations, but detailed tests in natural populations are scarce. We combine long-term population and fitness data with those from two types of molecular markers to examine the role of genetic effects in a declining metapopulation of southern dunlins Calidris alpina schinzii, an endangered shorebird. Results The decline is associated with increased pairings between related individuals, including close inbreeding (as revealed by both field observations of parentage and molecular markers. Furthermore, reduced genetic diversity seems to affect individual fitness at several life stages. Higher genetic similarity between mates correlates negatively with the pair's hatching success. Moreover, offspring produced by related parents are more homozygous and suffer from increased mortality during embryonic development and possibly also after hatching. Conclusions Our results demonstrate strong genetic effects in a rapidly declining population, emphasizing the importance of genetic factors for the persistence of small populations.

Chemosignals, hormones, and amphibian reproduction.

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Woodley, Sarah

2015-02-01

This article is part of a Special Issue "Chemosignals and Reproduction". Amphibians are often thought of as relatively simple animals especially when compared to mammals. Yet the chemosignaling systems used by amphibians are varied and complex. Amphibian chemosignals are particularly important in reproduction, in both aquatic and terrestrial environments. Chemosignaling is most evident in salamanders and newts, but increasing evidence indicates that chemical communication facilitates reproduction in frogs and toads as well. Reproductive hormones shape the production, dissemination, detection, and responsiveness to chemosignals. A large variety of chemosignals have been identified, ranging from simple, invariant chemosignals to complex, variable blends of chemosignals. Although some chemosignals elicit straightforward responses, others have relatively subtle effects. Review of amphibian chemosignaling reveals a number of issues to be resolved, including: 1) the significance of the complex, individually variable blends of courtship chemosignals found in some salamanders, 2) the behavioral and/or physiological functions of chemosignals found in anuran "breeding glands", 3) the ligands for amphibian V2Rs, especially V2Rs expressed in the main olfactory epithelium, and 4) the mechanism whereby transdermal delivery of chemosignals influences behavior. To date, only a handful of the more than 7000 species of amphibians has been examined. Further study of amphibians should provide additional insight to the role of chemosignals in reproduction. Copyright © 2014 Elsevier Inc. All rights reserved.

A novel copro-diagnostic molecular method for qualitative detection and identification of parasitic nematodes in amphibians and reptiles.

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Lucas G Huggins

Full Text Available Anthropogenic disturbance via resource acquisition, habitat fragmentation and climate change, amongst other factors, has led to catastrophic global biodiversity losses and species extinctions at an accelerating rate. Amphibians are currently one of the worst affected classes with at least a third of species categorised as being threatened with extinction. At the same time, they are also critically important for many habitats and provide man with a powerful proxy for ecosystem health by acting as a bioindicator group. Whilst the causes of synchronised amphibian losses are varied recent research has begun to highlight a growing role that macroparasites are playing in amphibian declines. However, diagnosing parasite infection in the field can be problematic, principally relying on collection and euthanasia of hosts, followed by necropsy and morphological identification of parasites in situ. The current study developed a non-invasive PCR-based methodology for sensitive detection and identification of parasitic nematode DNA released in the faeces of infected amphibians as egg or tissue fragments (environmental DNA. A DNA extraction protocol optimised for liberation of DNA from resilient parasite eggs was developed alongside the design of a novel, nematode universal, degenerate primer pair, thus avoiding the difficulties of using species specific primers in situations where common parasite species are unknown. Used in conjunction this protocol and primer pair was tested on a wide range of faecal samples from captive and wild amphibians. The primers and protocol were validated and detected infections, including a Railletnema nematode infection in poison dart frogs from ZSL London Zoo and Mantella cowani frogs in the wild. Furthermore, we demonstrate the efficacy of our PCR-based protocol for detecting nematode infection in other hosts, such as the presence of pinworm (Aspiculuris in two tortoise species and whipworm (Trichuris muris in mice. Our

A novel copro-diagnostic molecular method for qualitative detection and identification of parasitic nematodes in amphibians and reptiles.

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Huggins, Lucas G; Michaels, Christopher J; Cruickshank, Sheena M; Preziosi, Richard F; Else, Kathryn J

2017-01-01

Anthropogenic disturbance via resource acquisition, habitat fragmentation and climate change, amongst other factors, has led to catastrophic global biodiversity losses and species extinctions at an accelerating rate. Amphibians are currently one of the worst affected classes with at least a third of species categorised as being threatened with extinction. At the same time, they are also critically important for many habitats and provide man with a powerful proxy for ecosystem health by acting as a bioindicator group. Whilst the causes of synchronised amphibian losses are varied recent research has begun to highlight a growing role that macroparasites are playing in amphibian declines. However, diagnosing parasite infection in the field can be problematic, principally relying on collection and euthanasia of hosts, followed by necropsy and morphological identification of parasites in situ. The current study developed a non-invasive PCR-based methodology for sensitive detection and identification of parasitic nematode DNA released in the faeces of infected amphibians as egg or tissue fragments (environmental DNA). A DNA extraction protocol optimised for liberation of DNA from resilient parasite eggs was developed alongside the design of a novel, nematode universal, degenerate primer pair, thus avoiding the difficulties of using species specific primers in situations where common parasite species are unknown. Used in conjunction this protocol and primer pair was tested on a wide range of faecal samples from captive and wild amphibians. The primers and protocol were validated and detected infections, including a Railletnema nematode infection in poison dart frogs from ZSL London Zoo and Mantella cowani frogs in the wild. Furthermore, we demonstrate the efficacy of our PCR-based protocol for detecting nematode infection in other hosts, such as the presence of pinworm (Aspiculuris) in two tortoise species and whipworm (Trichuris muris) in mice. Our environmental DNA

ASSESSMENT OF THE RISK OF SOLAR ULTRAVIOLET RADIATION TO AMPHIBIANS: III. PREDICTION OF IMPACTS IN SELECTED NORTHERN MIDWESTERN WETLANDS

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The deleterious effects of solar ultraviolet radiation, especially the UV-B portion of sunlight, have been hypothesized to reduce survival, increase the frequency of malformations, and contribute to the apparent worldwide decline of many amphibian species.

Population size, survival, growth, and movements of Rana sierrae

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Fellers, Gary M.; Kleeman, Patrick M.; Miller, David A. W.; Halstead, Brian J.; Link, William

2013-01-01

Based on 2431 captures of 757 individual frogs over a 9-yr period, we found that the population of R. sierrae in one meadow–stream complex in Yosemite National Park ranged from an estimated 45 to 115 adult frogs. Rana sierrae at our relatively low elevation site (2200 m) grew at a fast rate (K = 0.73–0.78), had high overwintering survival rates (44.6–95%), lived a long time (up to 16 yr), and tended to be fairly sedentary during the summer (100% minimum convex polygon annual home ranges of 139 m2) but had low year-to-year site fidelity. Even though the amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) has been present in the population for at least 13 yr, there was no clear downward trend as might be expected from reports of R. sierrae population declines associated with Bd or from reports of widespread population decline of R. sierrae throughout its range.

Assessing the Threat of Amphibian Chytrid Fungus in the Albertine Rift: Past, Present and Future

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Seimon, Tracie A.; Ayebare, Samuel; Sekisambu, Robert; Muhindo, Emmanuel; Mitamba, Guillain; Greenbaum, Eli; Menegon, Michele; Pupin, Fabio; McAloose, Denise; Ammazzalorso, Alyssa; Meirte, Danny; Lukwago, Wilbur; Behangana, Mathias; Seimon, Anton; Plumptre, Andrew J.

2015-01-01

Batrachochytrium dendrobatidis (Bd), the cause of chytridiomycosis, is a pathogenic fungus that is found worldwide and is a major contributor to amphibian declines and extinctions. We report results of a comprehensive effort to assess the distribution and threat of Bd in one of the Earth’s most important biodiversity hotspots, the Albertine Rift in central Africa. In herpetological surveys conducted between 2010 and 2014, 1018 skin swabs from 17 amphibian genera in 39 sites across the Albertine Rift were tested for Bd by PCR. Overall, 19.5% of amphibians tested positive from all sites combined. Skin tissue samples from 163 amphibians were examined histologically; of these two had superficial epidermal intracorneal fungal colonization and lesions consistent with the disease chytridiomycosis. One amphibian was found dead during the surveys, and all others encountered appeared healthy. We found no evidence for Bd-induced mortality events, a finding consistent with other studies. To gain a historical perspective about Bd in the Albertine Rift, skin swabs from 232 museum-archived amphibians collected as voucher specimens from 1925–1994 were tested for Bd. Of these, one sample was positive; an Itombwe River frog (Phrynobatrachus asper) collected in 1950 in the Itombwe highlands. This finding represents the earliest record of Bd in the Democratic Republic of Congo. We modeled the distribution of Bd in the Albertine Rift using MaxEnt software, and trained our model for improved predictability. Our model predicts that Bd is currently widespread across the Albertine Rift, with moderate habitat suitability extending into the lowlands. Under climatic modeling scenarios our model predicts that optimal habitat suitability of Bd will decrease causing a major range contraction of the fungus by 2080. Our baseline data and modeling predictions are important for comparative studies, especially if significant changes in amphibian health status or climactic conditions are

DNA barcoding amphibians and reptiles.

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Vences, Miguel; Nagy, Zoltán T; Sonet, Gontran; Verheyen, Erik

2012-01-01

Only a few major research programs are currently targeting COI barcoding of amphibians and reptiles (including chelonians and crocodiles), two major groups of tetrapods. Amphibian and reptile species are typically old, strongly divergent, and contain deep conspecific lineages which might lead to problems in species assignment with incomplete reference databases. As far as known, there is no single pair of COI primers that will guarantee a sufficient rate of success across all amphibian and reptile taxa, or within major subclades of amphibians and reptiles, which means that the PCR amplification strategy needs to be adjusted depending on the specific research question. In general, many more amphibian and reptile taxa have been sequenced for 16S rDNA, which for some purposes may be a suitable complementary marker, at least until a more comprehensive COI reference database becomes available. DNA barcoding has successfully been used to identify amphibian larval stages (tadpoles) in species-rich tropical assemblages. Tissue sampling, DNA extraction, and amplification of COI is straightforward in amphibians and reptiles. Single primer pairs are likely to have a failure rate between 5 and 50% if taxa of a wide taxonomic range are targeted; in such cases the use of primer cocktails or subsequent hierarchical usage of different primer pairs is necessary. If the target group is taxonomically limited, many studies have followed a strategy of designing specific primers which then allow an easy and reliable amplification of all samples.

Effects of uncertainty and variability on population declines and IUCN Red List classifications.

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Rueda-Cediel, Pamela; Anderson, Kurt E; Regan, Tracey J; Regan, Helen M

2018-01-22

The International Union for Conservation of Nature (IUCN) Red List Categories and Criteria is a quantitative framework for classifying species according to extinction risk. Population models may be used to estimate extinction risk or population declines. Uncertainty and variability arise in threat classifications through measurement and process error in empirical data and uncertainty in the models used to estimate extinction risk and population declines. Furthermore, species traits are known to affect extinction risk. We investigated the effects of measurement and process error, model type, population growth rate, and age at first reproduction on the reliability of risk classifications based on projected population declines on IUCN Red List classifications. We used an age-structured population model to simulate true population trajectories with different growth rates, reproductive ages and levels of variation, and subjected them to measurement error. We evaluated the ability of scalar and matrix models parameterized with these simulated time series to accurately capture the IUCN Red List classification generated with true population declines. Under all levels of measurement error tested and low process error, classifications were reasonably accurate; scalar and matrix models yielded roughly the same rate of misclassifications, but the distribution of errors differed; matrix models led to greater overestimation of extinction risk than underestimations; process error tended to contribute to misclassifications to a greater extent than measurement error; and more misclassifications occurred for fast, rather than slow, life histories. These results indicate that classifications of highly threatened taxa (i.e., taxa with low growth rates) under criterion A are more likely to be reliable than for less threatened taxa when assessed with population models. Greater scrutiny needs to be placed on data used to parameterize population models for species with high growth rates

Fight Fungi with Fungi: Antifungal Properties of the Amphibian Mycobiome

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Patrick J. Kearns

2017-12-01

Full Text Available Emerging infectious diseases caused by fungal taxa are increasing and are placing a substantial burden on economies and ecosystems worldwide. Of the emerging fungal diseases, chytridomycosis caused by the fungus Batrachochytrium dendrobatidis (hereafter Bd is linked to global amphibian declines. Amphibians have innate immunity, as well as additional resistance through cutaneous microbial communities. Despite the targeting of bacteria as potential probiotics, the role of fungi in the protection against Bd infection in unknown. We used a four-part approach, including high-throughput sequencing of bacterial and fungal communities, cultivation of fungi, Bd challenge assays, and experimental additions of probiotic to Midwife Toads (Altyes obstetricans, to examine the overlapping roles of bacterial and fungal microbiota in pathogen defense in captive bred poison arrow frogs (Dendrobates sp.. Our results revealed that cutaneous fungal taxa differed from environmental microbiota across three species and a subspecies of Dendrobates spp. frogs. Cultivation of host-associated and environmental fungi realved numerous taxa with the ability to inhibit or facilitate the growth of Bd. The abundance of cutaneous fungi contributed more to Bd defense (~45% of the fungal community, than did bacteria (~10% and frog species harbored distinct inhibitory communities that were distinct from the environment. Further, we demonstrated that a fungal probiotic therapy did not induce an endocrine-immune reaction, in contrast to bacterial probiotics that stressed amphibian hosts and suppressed antimicrobial peptide responses, limiting their long-term colonization potential. Our results suggest that probiotic strategies against amphibian fungal pathogens should, in addition to bacterial probiotics, focus on host-associated and environmental fungi such as Penicillium and members of the families Chaetomiaceae and Lasiosphaeriaceae.

Fitness decline under osmotic stress in Caenorhabditis elegans populations subjected to spontaneous mutation accumulation at varying population sizes.

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Katju, Vaishali; Packard, Lucille B; Keightley, Peter D

2018-04-01

The consequences of mutations for population fitness depends on their individual selection coefficients and the effective population size. An earlier study of Caenorhabditis elegans spontaneous mutation accumulation lines evolved for 409 generations at three population sizes found that N e   = 1 populations declined significantly in fitness whereas the fitness of larger populations (N e   = 5, 50) was indistinguishable from the ancestral control under benign conditions. To test if larger MA populations harbor a load of cryptic deleterious mutations that are obscured under benign laboratory conditions, we measured fitness under osmotic stress via exposure to hypersaline conditions. The fitness of N e   = 1 lines exhibited a further decline under osmotic stress compared to benign conditions. However, the fitness of larger populations remained indistinguishable from that of the ancestral control. The average effects of deleterious mutations in N e   = 1 lines were estimated to be 22% for productivity and 14% for survivorship, exceeding values previously detected under benign conditions. Our results suggest that fitness decline is due to large effect mutations that are rapidly removed via selection even in small populations, with implications for conservation practices. Genetic stochasticity may not be as potent and immediate a threat to the persistence of small populations as other demographic and environmental stochastic factors. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

Identifying causes for population decline of the brown hare in agricultural landscapes in Denmark

DEFF Research Database (Denmark)

Jensen, Trine-Lee Wincentz

In recent decades the brown hare (Lepus europaeus) population in Denmark has undergone a substantial decline, but proximate causes are unknown and little is known about actual densities. In this thesis, hare populations are investigated with respect to age composition and reproductive parameters...... proportions in game bags have dropped significantly since the 1950ies. Simple matrix population models with variable juvenile recruitment predict the similar population growth rates as actually observed in the annual bag records. The model substantiates the supposition that declines in the Danish hare...

Interactive effects of wildfire, forest management, and isolation on amphibian and parasite abundance

Science.gov (United States)

Hossack, Blake R.; Corn, P. Stephen; Winsor H. Lowe,; R. Kenneth Honeycutt,; Sean A. Parks,

2013-01-01

Projected increases in wildfire and other climate-driven disturbances will affect populations and communities worldwide, including host–parasite relationships. Research in temperate forests has shown that wildfire can negatively affect amphibians, but this research has occurred primarily outside of managed landscapes where interactions with human disturbances could result in additive or synergistic effects. Furthermore, parasites represent a large component of biodiversity and can affect host fitness and population dynamics, yet they are rarely included in studies of how vertebrate hosts respond to disturbance. To determine how wildfire affects amphibians and their parasites, and whether effects differ between protected and managed landscapes, we compared abundance of two amphibians and two nematodes relative to wildfire extent and severity around wetlands in neighboring protected and managed forests (Montana, USA). Population sizes of adult, male long-toed salamanders (Ambystoma macrodactylum) decreased with increased burn severity, with stronger negative effects on isolated populations and in managed forests. In contrast, breeding population sizes of Columbia spotted frogs (Rana luteiventris) increased with burn extent in both protected and managed protected forests. Path analysis showed that the effects of wildfire on the two species of nematodes were consistent with differences in their life history and transmission strategies and the responses of their hosts. Burn severity indirectly reduced abundance of soil-transmitted Cosmocercoides variabilis through reductions in salamander abundance. Burn severity also directly reduced C. variabilis abundance, possibly though changes in soil conditions. For the aquatically transmitted nematode Gyrinicola batrachiensis, the positive effect of burn extent on density of Columbia spotted frog larvae indirectly increased parasite abundance. Our results show that effects of wildfire on amphibians depend upon burn extent

Widespread presence of the pathogenic fungus Batrachochytrium dendrobatidis in wild amphibian communities in Madagascar

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Bletz, Molly C.; Rosa, Gonçalo M.; Andreone, Franco; Courtois, Elodie A.; Schmeller, Dirk S.; Rabibisoa, Nirhy H. C.; Rabemananjara, Falitiana C. E.; Raharivololoniaina, Liliane; Vences, Miguel; Weldon, Ché; Edmonds, Devin; Raxworthy, Christopher J.; Harris, Reid N.; Fisher, Matthew C.; Crottini, Angelica

2015-01-01

Amphibian chytridiomycosis, an emerging infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd), has been a significant driver of amphibian declines. While globally widespread, Bd had not yet been reported from within Madagascar. We document surveys conducted across the country between 2005 and 2014, showing Bd's first record in 2010. Subsequently, Bd was detected in multiple areas, with prevalence reaching up to 100%. Detection of Bd appears to be associated with mid to high elevation sites and to have a seasonal pattern, with greater detectability during the dry season. Lineage-based PCR was performed on a subset of samples. While some did not amplify with any lineage probe, when a positive signal was observed, samples were most similar to the Global Panzootic Lineage (BdGPL). These results may suggest that Bd arrived recently, but do not exclude the existence of a previously undetected endemic Bd genotype. Representatives of all native anuran families have tested Bd-positive, and exposure trials confirm infection by Bd is possible. Bd's presence could pose significant threats to Madagascar's unique “megadiverse” amphibians. PMID:25719857

Ovarian control and monitoring in amphibians.

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Calatayud, N E; Stoops, M; Durrant, B S

2018-03-15

Amphibian evolution spans over 350 million years, consequently this taxonomic group displays a wide, complex array of physiological adaptations and their diverse modes of reproduction are a prime example. Reproduction can be affected by taxonomy, geographic and altitudinal distribution, and environmental factors. With some exceptions, amphibians can be categorized into discontinuous (strictly seasonal) and continuous breeders. Temperature and its close association with other proximate and genetic factors control reproduction via a tight relationship with circadian rhythms which drive genetic and hormonal responses to the environment. In recent times, the relationship of proximate factors and reproduction has directly or indirectly lead to the decline of this taxonomic group. Conservationists are tackling the rapid loss of species through a wide range of approaches including captive rescue. However, there is still much to be learned about the mechanisms of reproductive control and its requirements in order to fabricate species-appropriate captive environments that address a variety of reproductive strategies. As with other taxonomic groups, assisted reproductive technologies and other reproductive monitoring tools such as ultrasound, hormone analysis and body condition indices can assist conservationists in optimizing captive husbandry and breeding. In this review we discuss some of the mechanisms of ovarian control and the different tools being used to monitor female reproduction. Copyright © 2018 Elsevier Inc. All rights reserved.

Sixty years of anthropogenic pressure: a spatio-temporal genetic analysis of brown trout populations subject to stocking and population declines

DEFF Research Database (Denmark)

Hansen, Michael Møller; Fraser, Dylan J.; Meier, Kristian

2009-01-01

Analyses of historical samples can provide invaluable information on changes to the genetic composition of natural populations resulting from human activities. Here, we analyse 21 microsatellite loci in historical (archived scales from 1927 to 1956) and contemporary samples of brown trout (Salmo...... trutta) from six neighbouring rivers in Denmark, to compare the genetic structure of wild populations before and after population declines and stocking with nonlocal strains of hatchery trout. We show that all populations have been strongly affected by stocking, with admixture proportions ranging from 14...... differences among populations in hatchery trout admixture proportions. Despite significant changes to the genetic composition within populations over time, dispersal rates among populations were roughly similar before and after stocking. We also assessed whether population declines or introgression...

Detection of the emerging amphibian pathogens Batrachochytrium dendrobatidis and ranavirus in Russia

Science.gov (United States)

Reshetnikov, Andrey N.; Chestnut, Tara E.; Brunner, Jesse L.; Charles, Kaylene M.; Nebergall, Emily E.; Olson, Deanna H.

2014-01-01

In a population of the European common toad Bufo bufo from a rural pond in the region of Lake Glubokoe Regional Reserve in Moscow province, Russia, unexplained mass mortality events involving larvae and metamorphs have been observed over a monitoring period of >20 yr. We tested toads from this and a nearby site for the emerging amphibian pathogens Batrachochytrium dendrobatidis (Bd) and ranavirus (Rv). Both pathogens were detected, and at the rural pond site, with the above-noted losses and decline in toad breeding success, 40% of B. bufo metamorphs were Bd positive, 46% were Rv positive and 20% were co-infected with both pathogens. Toad metamorphs from a neighbouring water body were also Bd and Rv positive (25 and 55%, respectively). This is the first confirmation of these pathogens in Russia. Questions remain as to the origins of these pathogens in Russia and their roles in documented mass mortality events.

Cadmium pollution and amphibians--Studies in tadpoles of Rana limnocharis.

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Patar, Arabinda; Giri, Anirudha; Boro, Freeman; Bhuyan, Krishna; Singha, Utsab; Giri, Sarbani

2016-02-01

Cadmium is released into the environment in increasing amounts from different natural and anthropogenic activities contaminating the aquatic habitats. Amphibian tadpoles develop in water and hence are likely to be adversely affected by cadmium present in the aquatic environment. We have studied the toxic and genotoxic effects of CdCl2 on the tadpoles of Rana limnocharis. CdCl2 in the concentration range between 0.1 and 0.4 mg/L induced significant mortality in R. limnocharis tadpoles in a dose and time dependent manner. The 10-day LC50 which has more ecological relevance was far less than the 24-h LC50. Tadpoles exposed to CdCl2 metamorphosed at an early age possibly as a survival strategy to move out of the stressful environment. The body weight of the CdCl2 exposed animals at metamorphosis was lower compared to the control individuals which may affect survival and reproductive fitness in adult life. Besides, the average body length of the metamorphosed individuals in the CdCl2 exposed group was higher than the control group. CdCl2 was found to be genotoxic in micronucleus test and comet assay. The ambient concentration of Cd could reach up to 60 μg/L or more. Exposure to 18.5 μg/L of CdCl2 (1% of 24-h LC50) induced significant increase in DNA strand breaks as compared to the control. The present findings demonstrate that presence of cadmium in the aquatic environment can significantly alter the life history traits and cause DNA damage in amphibians and hence, could contribute towards their population decline. Copyright © 2015 Elsevier Ltd. All rights reserved.

Marginal Bayesian nonparametric model for time to disease arrival of threatened amphibian populations.

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Zhou, Haiming; Hanson, Timothy; Knapp, Roland

2015-12-01

The global emergence of Batrachochytrium dendrobatidis (Bd) has caused the extinction of hundreds of amphibian species worldwide. It has become increasingly important to be able to precisely predict time to Bd arrival in a population. The data analyzed herein present a unique challenge in terms of modeling because there is a strong spatial component to Bd arrival time and the traditional proportional hazards assumption is grossly violated. To address these concerns, we develop a novel marginal Bayesian nonparametric survival model for spatially correlated right-censored data. This class of models assumes that the logarithm of survival times marginally follow a mixture of normal densities with a linear-dependent Dirichlet process prior as the random mixing measure, and their joint distribution is induced by a Gaussian copula model with a spatial correlation structure. To invert high-dimensional spatial correlation matrices, we adopt a full-scale approximation that can capture both large- and small-scale spatial dependence. An efficient Markov chain Monte Carlo algorithm with delayed rejection is proposed for posterior computation, and an R package spBayesSurv is provided to fit the model. This approach is first evaluated through simulations, then applied to threatened frog populations in Sequoia-Kings Canyon National Park. © 2015, The International Biometric Society.

Chytrid fungus acts as a generalist pathogen infecting species-rich amphibian families in Brazilian rainforests.

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Valencia-Aguilar, Anyelet; Ruano-Fajardo, Gustavo; Lambertini, Carolina; da Silva Leite, Domingos; Toledo, Luís Felipe; Mott, Tamí

2015-05-11

The fungus Batrachochytrium dendrobatidis (Bd) is among the main causes of declines in amphibian populations. This fungus is considered a generalist pathogen because it infects several species and spreads rapidly in the wild. To date, Bd has been detected in more than 100 anuran species in Brazil, mostly in the southern portion of the Atlantic forest. Here, we report survey data from some poorly explored regions; these data considerably extend current information on the distribution of Bd in the northern Atlantic forest region. In addition, we tested the hypothesis that Bd is a generalist pathogen in this biome. We also report the first positive record for Bd in an anuran caught in the wild in Amazonia. In total, we screened 90 individuals (from 27 species), of which 39 individuals (from 22 species) were Bd-positive. All samples collected in Bahia (2 individuals), Pernambuco (3 individuals), Pará (1 individual), and Minas Gerais (1 individual) showed positive results for Bd. We found a positive correlation between anuran richness per family and the number of infected species in the Atlantic forest, supporting previous observations that Bd lacks strong host specificity; of 38% of the anuran species in the Atlantic forest that were tested for Bd infection, 25% showed positive results. The results of our study exemplify the pandemic and widespread nature of Bd infection in amphibians.

A frog's-eye view of the landscape : quantifying connectivity for fragmented amphibian populations

NARCIS (Netherlands)

Vos, C.C.

1999-01-01

The spatial habitat requirements are studied for two amphibian species: the tree frog ( Hyla arborea ) and the moor frog ( Rana arvalis ). Fragmentation, the destruction of suitable habitat, results in small fragments that are separated by

Future potential distribution of the emerging amphibian chytrid fungus under anthropogenic climate change.

Science.gov (United States)

Rödder, Dennis; Kielgast, Jos; Lötters, Stefan

2010-11-01

Anthropogenic climate change poses a major threat to global biodiversity with a potential to alter biological interactions at all spatial scales. Amphibians are the most threatened vertebrates and have been subject to increasing conservation attention over the past decade. A particular concern is the pandemic emergence of the parasitic chytrid fungus Batrachochytrium dendrobatidis, which has been identified as the cause of extremely rapid large-scale declines and species extinctions. Experimental and observational studies have demonstrated that the host-pathogen system is strongly influenced by climatic parameters and thereby potentially affected by climate change. Herein we project a species distribution model of the pathogen onto future climatic scenarios generated by the IPCC to examine their potential implications on the pandemic. Results suggest that predicted anthropogenic climate change may reduce the geographic range of B. dendrobatidis and its potential influence on amphibian biodiversity.

Diversity, natural history and conservation of amphibians and reptiles from the San Vito Region, southwestern Costa Rica.

Science.gov (United States)

Santos-Barrera, Georgina; Pacheco, Jesus; Mendoza-Quijano, Fernando; Bolaños, Federico; Cháves, Gerardo; Daily, Gretchen C; Ehrlich, Paul R; Ceballos, Gerardo

2008-06-01

We present an inventory of the amphibians and reptiles of the San Vito de Coto Brus region, including the Las Cruces Biological Station, in southern Costa Rica, which is the result of a survey of the herpetofauna occurring in mountain forest fragments, pastures, coffee plantations, and other disturbed areas. We found 67 species, included 26 species of amphibians and of 41 of reptiles. We describe the distribution patterns of the community on the basis of the life zones, elevation, fragmentation, and degree of anthropogenic impact. We also provide some nouvelle data on the systematics of some select taxa, their geographical ranges, microhabitats, activity, and other relevant ecological and natural history features. Finally, we comment on the present conservation status of the herpetofauna in the region. Previous literature and collection records indicate a higher number of species occurring in this area, which suggests that some declines have occurred, especially of amphibians, in last decades.

Is Declining malaria vector population in Africa a result of intervention Measures or sampling tools inefficiency?

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Eliningaya Kweka

2013-01-01

Full Text Available Recent entomological surveys have shown a declining trend of malaria vector population in sub-Saharan Africa and the observation have beenassociated with the scale-up and intensive use of malaria intervention measures such as insecticides treated nets and insecticide residual sprays.However, little is known on the contribution of the mosquito sampling tools inefficiency on the declining trends of malaria vector population. Inthis commentary paper, we explore the possibility of contribution of mosquito sampling tools’ inefficiency to the observed declining trends ofmalaria vector population in Africa.

Emerging contaminants and their potential effects on amphibians and reptiles

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Serious threats to the health and sustainability of global amphibian populations have been well documented over the last few decades. Encroachment upon and destruction of primary habitat is the most critical threat, but some species have disappeared while their habitat remains. Additional stressor...

Compensatory effects of recruitment and survival when amphibian populations are perturbed by disease

Science.gov (United States)

Muths, E.; Scherer, R. D.; Pilliod, D.S.

2011-01-01

The need to increase our understanding of factors that regulate animal population dynamics has been catalysed by recent, observed declines in wildlife populations worldwide. Reliable estimates of demographic parameters are critical for addressing basic and applied ecological questions and understanding the response of parameters to perturbations (e.g. disease, habitat loss, climate change). However, to fully assess the impact of perturbation on population dynamics, all parameters contributing to the response of the target population must be estimated. We applied the reverse-time model of Pradel in Program mark to 6years of capture-recapture data from two populations of Anaxyrus boreas (boreal toad) populations, one with disease and one without. We then assessed a priori hypotheses about differences in survival and recruitment relative to local environmental conditions and the presence of disease. We further explored the relative contribution of survival probability and recruitment rate to population growth and investigated how shifts in these parameters can alter population dynamics when a population is perturbed. High recruitment rates (0??41) are probably compensating for low survival probability (range 0??51-0??54) in the population challenged by an emerging pathogen, resulting in a relatively slow rate of decline. In contrast, the population with no evidence of disease had high survival probability (range 0??75-0??78) but lower recruitment rates (0??25). Synthesis and applications.We suggest that the relationship between survival and recruitment may be compensatory, providing evidence that populations challenged with disease are not necessarily doomed to extinction. A better understanding of these interactions may help to explain, and be used to predict, population regulation and persistence for wildlife threatened with disease. Further, reliable estimates of population parameters such as recruitment and survival can guide the formulation and implementation of

Amphibians and reptiles of South Ossetia

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Boris S. Tuniyev

2017-05-01

Full Text Available For the first time we have summarised the results of the study of batraho- and herpetofauna of the Republic of South Ossetia. We present an Annotated List of species as authentically living in the region, as well as ever mentioned for it in literature, field notebooks, museum collections and our own expeditions in South Ossetia. The batrachofauna of the Republic of South Ossetia counts nine species and the herpetofauna 19 species. It provides a complete inventory of all finds (65 localities. A number of confirmed species have been assigned for the first time in scientific literature for the territory of South Ossetia: Emys orbicularis, Darevskia mixta, Natrix megalocephala, Hierophis schmidti, Pelias dinniki, P. kaznakovi. We detected the morphological specificity of the South Ossetia' populations of Darevskia praticola, D. brauneri and D. caucasica. The Assessment of conservation status has been evaluated for all forms of amphibians and reptiles in the region. According to its results, five amphibian species and ten reptile species are recommended for inclusion into the Red Data Book of the Republic of South Ossetia. The central problem of environmental activities in the Region is the lack of a network of different rank protected areas covering all natural zones and altitudinal belts. The South Ossetian State Nature Reserve is the single protected area of South Ossetia, which provides protection only for three endangered species of amphibians and three species of reptiles.

Can we enhance amphibians' habitat restoration in the post-mining areas?

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Klimaszewski, Krzysztof; Pacholik, Ewa; Snopek, Adam

2016-09-01

The study was aimed to evaluate the selected improvements of nature restoration in a depleted gravel pit. The study site consisted of four water reservoirs of different shapes and sizes, flooded after the gravel extraction ended. Ecological succession monitoring, conducted by the Warsaw University of Life Sciences students associated in the Student Scientific Association of Animal Sciences Faculty since the completion of mining, have focused on amphibians. A twofold approach upheld amphibian species population dynamics, as well as selected habitat elements. The restoration practices dedicated to habitat conditions enhancing have been proved to be definitely effective and useful for similar sites.

Dealing with China's future population decline: a proposal for replacing low birth rates with sustainable rates.

Science.gov (United States)

Cao, Shixiong; Wang, Xiuqing

2009-09-01

Decreasing population levels due to declining birth rates are becoming a potentially serious social problem in developed and rapidly developing countries. China urgently needed to reduce birth rates so that its population would decline to a sustainable level, and the family planning policy designed to achieve this goal has largely succeeded. However, continuing to pursue this policy is leading to serious, unanticipated problems such as a shift in the country's population distribution towards the elderly and increasing difficulty supporting that elderly population. Social and political changes that promoted low birth rates and the lack of effective policies to encourage higher birth rates suggest that mitigating the consequences of the predicted population decline will depend on a revised approach based on achieving sustainable birth rates.

Amphibian Engineers in the Southwest Pacific

Science.gov (United States)

2017-03-08

too dangerous. The 1st Engineer Amphibian Brigade was relegated to truck duty in England instead of preparing for the cross-channel invasion.21 Before...and dumps through the swamp.93 91 Office of the Chief Engineer , Amphibian Engineer ...inland, whereas the DUKW (and LVT) could drive direct from ship to dump site. 116 Office of the Chief Engineer , Amphibian Engineer Operations, 320-21

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Indian Academy of Sciences (India)

Unknown

population of amphibians, especially of frogs and salamanders, over the past 40 years: “The most serious population decline may have occurred long before scientists noticed and sounded the alarm”. Their analysis concluded that the world's amphibian population has decreased by more than 50% since the 1950s.

Glutathione S-transferase genotypes modify lung function decline in the general population: SAPALDIA cohort study

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Ackermann-Liebrich Ursula

2007-01-01

Full Text Available Abstract Background Understanding the environmental and genetic risk factors of accelerated lung function decline in the general population is a first step in a prevention strategy against the worldwide increasing respiratory pathology of chronic obstructive pulmonary disease (COPD. Deficiency in antioxidative and detoxifying Glutathione S-transferase (GST gene has been associated with poorer lung function in children, smokers and patients with respiratory diseases. In the present study, we assessed whether low activity variants in GST genes are also associated with accelerated lung function decline in the general adult population. Methods We examined with multiple regression analysis the association of polymorphisms in GSTM1, GSTT1 and GSTP1 genes with annual decline in FEV1, FVC, and FEF25–75 during 11 years of follow-up in 4686 subjects of the prospective SAPALDIA cohort representative of the Swiss general population. Effect modification by smoking, gender, bronchial hyperresponisveness and age was studied. Results The associations of GST genotypes with FEV1, FVC, and FEF25–75 were comparable in direction, but most consistent for FEV1. GSTT1 homozygous gene deletion alone or in combination with GSTM1 homozygous gene deletion was associated with excess decline in FEV1 in men, but not women, irrespective of smoking status. The additional mean annual decline in FEV1 in men with GSTT1 and concurrent GSTM1 gene deletion was -8.3 ml/yr (95% confidence interval: -12.6 to -3.9 relative to men without these gene deletions. The GSTT1 effect on the FEV1 decline comparable to the observed difference in FEV1 decline between never and persistent smoking men. Effect modification by gender was statistically significant. Conclusion Our results suggest that genetic GSTT1 deficiency is a prevalent and strong determinant of accelerated lung function decline in the male general population.

Population decline in the Delta caribou herd with reference to other Alaskan herds

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Patrick Valkenburg et al.

1996-01-01

Full Text Available After growing continuously for nearly 15 years, the Delta caribou herd began to decline in 1989. Most other Interior Alaskan herds also began declining. In the Delta herd, and in other herds, the declines were caused primarily by high summer mortality of calves and increased natural mortality of adult females. Other minor causes included increased winter mortality of calves, and reduced parturition rates of 3-year-old and older females. The decline in the Delta herd also coincided with increased wolf (Canis lupus numbers, winters with deeper than normal snow, and warm summers. Mean body weight of annual samples of 10-month-old female calves was consistently low during the decline. Except in some of the smallest Interior Alaskan herds, we conclude that evidence for population regulation in Alaskan caribou is weak, and that herds are likely to fluctuate within a wide range of densities due to complex interactions of predation and weather. Unless wolf numbers are influenced by man, the size of a caribou herd in a given year is likely to be largely a function of its size during the previous population low and the number of years of favorable weather in the interim.

Presence of amphibian chytrid fungus (Batrachochytrium dendrobatidis) in rainwater suggests aerial dispersal is possible

Science.gov (United States)

Kolby, Jonathan E.; Sara D. Ramirez,; Lee Berger,; Griffin, Dale W.; Merlijn Jocque,; Lee F. Skerratt,

2015-01-01

Abstract Global spread of the pathogenic amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) may involve dispersal mechanisms not previously explored. Weather systems accompanied by strong wind and rainfall have been known to assist the dispersal of microbes pathogenic to plants and animals, and we considered a similar phenomenon might occur with Bd. We investigated this concept by sampling rainwater from 20 precipitation events for the presence of Bd in Cusuco National Park, Honduras: a site where high Bd prevalence was previously detected in stream-associated amphibians. Quantitative PCR analysis confirmed the presence of Bd in rainwater in one (5 %) of the weather events sampled, although viability cannot be ascertained from molecular presence alone. The source of the Bd and distance that the contaminated rainwater traveled could not be determined; however, this collection site was located approximately 600 m from the nearest observed perennial river by straight-line aerial distance. Although our results suggest atmospheric Bd dispersal is uncommon and unpredictable, even occasional short-distance aerial transport could considerably expand the taxonomic diversity of amphibians vulnerable to exposure and at risk of decline, including terrestrial and arboreal species that are not associated with permanent water bodies.

Adaptive responses to salinity stress across multiple life stages in anuran amphibians.

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Albecker, Molly A; McCoy, Michael W

2017-01-01

In many regions, freshwater wetlands are increasing in salinity at rates exceeding historic levels. Some freshwater organisms, like amphibians, may be able to adapt and persist in salt-contaminated wetlands by developing salt tolerance. Yet adaptive responses may be more challenging for organisms with complex life histories, because the same environmental stressor can require responses across different ontogenetic stages. Here we investigated responses to salinity in anuran amphibians: a common, freshwater taxon with a complex life cycle. We conducted a meta-analysis to define how the lethality of saltwater exposure changes across multiple life stages, surveyed wetlands in a coastal region experiencing progressive salinization for the presence of anurans, and used common garden experiments to investigate whether chronic salt exposure alters responses in three sequential life stages (reproductive, egg, and tadpole life stages) in Hyla cinerea , a species repeatedly observed in saline wetlands. Meta-analysis revealed differential vulnerability to salt stress across life stages with the egg stage as the most salt-sensitive. Field surveys revealed that 25% of the species known to occur in the focal region were detected in salt-intruded habitats. Remarkably, Hyla cinerea was found in large abundances in multiple wetlands with salinity concentrations 450% higher than the tadpole-stage LC 50 . Common garden experiments showed that coastal (chronically salt exposed) populations of H. cinerea lay more eggs, have higher hatching success, and greater tadpole survival in higher salinities compared to inland (salt naïve) populations. Collectively, our data suggest that some species of anuran amphibians have divergent and adaptive responses to salt exposure across populations and across different life stages. We propose that anuran amphibians may be a novel and amenable natural model system for empirical explorations of adaptive responses to environmental change.

The use of population viability analysis to identify possible factors contributing to the decline of a rare ungulate population in south-eastern Zimbabwe

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Simon D. Capon

2013-02-01

Full Text Available Populations that are vulnerable to decline are of particular concern to wildlife managers and uncovering the mechanisms responsible for downward trends is a crucial step towards developing future viable populations. The aims of this study were to better understand the mechanisms behind the historic decline of the sable antelope, Hippotragus niger, population at the Malilangwe Wildlife Reserve (MWR, to assess its future viability and to use this analysis to determine key areas of breakdown in population growth and link these to potential limiting factors. VORTEX, a population viability model was used to assess the future viability of the sable antelope population and a sensitivity analysis was applied to identify the key areas of breakdown in growth. The sable population is currently viable, but remains highly vulnerable to changes in adult female survival, a factor which had the greatest influence on overall population fitness. Lion predation, impacting on the adult segment of the population, appeared to be the main factor responsible for the historic decline at the MWR.Conservation implications: Sable generally occur at low densities in the lowveld region of Zimbabwe and, as such, populations are vulnerable to increases in mortality rates. The role of lions in driving the decline at the MWR suggests a need to control their numbers and develop prey refuges through improved management of artificial water.

Effects of an infectious fungus, Batrachochytrium dendrobatidis, on amphibian predator-prey interactions.

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Barbara A Han

2011-02-01

Full Text Available The effects of parasites and pathogens on host behaviors may be particularly important in predator-prey contexts, since few animal behaviors are more crucial for ensuring immediate survival than the avoidance of lethal predators in nature. We examined the effects of an emerging fungal pathogen of amphibians, Batrachochytrium dendrobatidis, on anti-predator behaviors of tadpoles of four frog species. We also investigated whether amphibian predators consumed infected prey, and whether B. dendrobatidis caused differences in predation rates among prey in laboratory feeding trials. We found differences in anti-predator behaviors among larvae of four amphibian species, and show that infected tadpoles of one species (Anaxyrus boreas were more active and sought refuge more frequently when exposed to predator chemical cues. Salamander predators consumed infected and uninfected tadpoles of three other prey species at similar rates in feeding trials, and predation risk among prey was unaffected by B. dendrobatidis. Collectively, our results show that even sub-lethal exposure to B. dendrobatidis can alter fundamental anti-predator behaviors in some amphibian prey species, and suggest the unexplored possibility that indiscriminate predation between infected and uninfected prey (i.e., non-selective predation could increase the prevalence of this widely distributed pathogen in amphibian populations. Because one of the most prominent types of predators in many amphibian systems is salamanders, and because salamanders are susceptible to B. dendrobatidis, our work suggests the importance of considering host susceptibility and behavioral changes that could arise from infection in both predators and prey.

New species of Cryptosporidium Tyzzer, 1907 (Apicomplexa) from amphibian host: morphology, biology and phylogeny

Czech Academy of Sciences Publication Activity Database

Jirků, Miloslav; Valigurová, A.; Koudela, Břetislav; Křížek, Jaroslav; Modrý, David; Šlapeta, J.

2008-01-01

Roč. 55, č. 2 (2008), s. 81-94 ISSN 0015-5683 R&D Projects: GA ČR GD524/03/H133; GA ČR GA524/05/0992; GA MŠk LC522 Institutional research plan: CEZ:AV0Z60220518 Keywords : Cryptosporidium fragile * new species * Duttaphrynus melanostictus * Host specificity * ultrastructure * global amphibian decline * hylogeny * quarantine Subject RIV: EG - Zoology Impact factor: 1.307, year: 2008

Global climate change, war, and population decline in recent human history.

Science.gov (United States)

Zhang, David D; Brecke, Peter; Lee, Harry F; He, Yuan-Qing; Zhang, Jane

2007-12-04

Although scientists have warned of possible social perils resulting from climate change, the impacts of long-term climate change on social unrest and population collapse have not been quantitatively investigated. In this study, high-resolution paleo-climatic data have been used to explore at a macroscale the effects of climate change on the outbreak of war and population decline in the preindustrial era. We show that long-term fluctuations of war frequency and population changes followed the cycles of temperature change. Further analyses show that cooling impeded agricultural production, which brought about a series of serious social problems, including price inflation, then successively war outbreak, famine, and population decline successively. The findings suggest that worldwide and synchronistic war-peace, population, and price cycles in recent centuries have been driven mainly by long-term climate change. The findings also imply that social mechanisms that might mitigate the impact of climate change were not significantly effective during the study period. Climate change may thus have played a more important role and imposed a wider ranging effect on human civilization than has so far been suggested. Findings of this research may lend an additional dimension to the classic concepts of Malthusianism and Darwinism.

The Role of Responses to Experiences of Rural Population Decline in the Social Capital of Families

NARCIS (Netherlands)

Elshof, Hans; Bailey, Ajay

2015-01-01

Population decline in rural areas has an impact on rural villages. This research investigates to what extent families with children in rural villages experience consequences of population decline, in which ways they respond to these experiences, and how that plays a role in their individual social

Conservation genetics of extremely isolated urban populations of the northern dusky salamander (Desmognathus fuscus in New York City

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Jason Munshi-South

2013-04-01

Full Text Available Urbanization is a major cause of amphibian decline. Stream-dwelling plethodontid salamanders are particularly susceptible to urbanization due to declining water quality and hydrological changes, but few studies have examined these taxa in cities. The northern dusky salamander (Desmognathus fuscus was once common in the New York City metropolitan area, but has substantially declined throughout the region in recent decades. We used five tetranucleotide microsatellite loci to examine population differentiation, genetic variation, and bottlenecks among five remnant urban populations of dusky salamanders in NYC. These genetic measures provide information on isolation, prevalence of inbreeding, long-term prospects for population persistence, and potential for evolutionary responses to future environmental change. All populations were genetically differentiated from each other, and the most isolated populations in Manhattan have maintained very little genetic variation (i.e. <20% heterozygosity. A majority of the populations also exhibited evidence of genetic bottlenecks. These findings contrast with published estimates of high genetic variation within and lack of structure between populations of other desmognathine salamanders sampled over similar or larger spatial scales. Declines in genetic variation likely resulted from population extirpations and the degradation of stream and terrestrial paths for dispersal in NYC. Loss of genetic variability in populations isolated by human development may be an underappreciated cause and/or consequence of the decline of this species in urbanized areas of the northeast USA.

Lion (Panthera leo) populations are declining rapidly across Africa, except in intensively managed areas.

Science.gov (United States)

Bauer, Hans; Chapron, Guillaume; Nowell, Kristin; Henschel, Philipp; Funston, Paul; Hunter, Luke T B; Macdonald, David W; Packer, Craig

2015-12-01

We compiled all credible repeated lion surveys and present time series data for 47 lion (Panthera leo) populations. We used a Bayesian state space model to estimate growth rate-λ for each population and summed these into three regional sets to provide conservation-relevant estimates of trends since 1990. We found a striking geographical pattern: African lion populations are declining everywhere, except in four southern countries (Botswana, Namibia, South Africa, and Zimbabwe). Population models indicate a 67% chance that lions in West and Central Africa decline by one-half, while estimating a 37% chance that lions in East Africa also decline by one-half over two decades. We recommend separate regional assessments of the lion in the World Conservation Union (IUCN) Red List of Threatened Species: already recognized as critically endangered in West Africa, our analysis supports listing as regionally endangered in Central and East Africa and least concern in southern Africa. Almost all lion populations that historically exceeded ∼ 500 individuals are declining, but lion conservation is successful in southern Africa, in part because of the proliferation of reintroduced lions in small, fenced, intensively managed, and funded reserves. If management budgets for wild lands cannot keep pace with mounting levels of threat, the species may rely increasingly on these southern African areas and may no longer be a flagship species of the once vast natural ecosystems across the rest of the continent.

Chironomidae bloodworms larvae as aquatic amphibian food.

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Fard, Mojdeh Sharifian; Pasmans, Frank; Adriaensen, Connie; Laing, Gijs Du; Janssens, Geert Paul Jules; Martel, An

2014-01-01

Different species of chironomids larvae (Diptera: Chironomidae) so-called bloodworms are widely distributed in the sediments of all types of freshwater habitats and considered as an important food source for amphibians. In our study, three species of Chironomidae (Baeotendipes noctivagus, Benthalia dissidens, and Chironomus riparius) were identified in 23 samples of larvae from Belgium, Poland, Russia, and Ukraine provided by a distributor in Belgium. We evaluated the suitability of these samples as amphibian food based on four different aspects: the likelihood of amphibian pathogens spreading, risk of heavy metal accumulation in amphibians, nutritive value, and risk of spreading of zoonotic bacteria (Salmonella, Campylobacter, and ESBL producing Enterobacteriaceae). We found neither zoonotic bacteria nor the amphibian pathogens Ranavirus and Batrachochytrium dendrobatidis in these samples. Our data showed that among the five heavy metals tested (Hg, Cu, Cd, Pb, and Zn), the excess level of Pb in two samples and low content of Zn in four samples implicated potential risk of Pb accumulation and Zn inadequacy. Proximate nutritional analysis revealed that, chironomidae larvae are consistently high in protein but more variable in lipid content. Accordingly, variations in the lipid: protein ratio can affect the amount and pathway of energy supply to the amphibians. Our study indicated although environmentally-collected chironomids larvae may not be vectors of specific pathogens, they can be associated with nutritional imbalances and may also result in Pb bioaccumulation and Zn inadequacy in amphibians. Chironomidae larvae may thus not be recommended as single diet item for amphibians. © 2014 Wiley Periodicals, Inc.

Suitability of amphibians and reptiles for translocation.

Science.gov (United States)

Germano, Jennifer M; Bishop, Phillip J

2009-02-01

Translocations are important tools in the field of conservation. Despite increased use over the last few decades, the appropriateness of translocations for amphibians and reptiles has been debated widely over the past 20 years. To provide a comprehensive evaluation of the suitability of amphibians and reptiles for translocation, we reviewed the results of amphibian and reptile translocation projects published between 1991 and 2006. The success rate of amphibian and reptile translocations reported over this period was twice that reported in an earlier review in 1991. Success and failure rates were independent of the taxonomic class (Amphibia or Reptilia) released. Reptile translocations driven by human-wildlife conflict mitigation had a higher failure rate than those motivated by conservation, and more recent projects of reptile translocations had unknown outcomes. The outcomes of amphibian translocations were significantly related to the number of animals released, with projects releasing over 1000 individuals being most successful. The most common reported causes of translocation failure were homing and migration of introduced individuals out of release sites and poor habitat. The increased success of amphibian and reptile translocations reviewed in this study compared with the 1991 review is encouraging for future conservation projects. Nevertheless, more preparation, monitoring, reporting of results, and experimental testing of techniques and reintroduction questions need to occur to improve translocations of amphibians and reptiles as a whole.

Genetic structure and evidence for recent population decline in Eurasian otter populations in the Czech and Slovak Republics: implications for conservation

DEFF Research Database (Denmark)

Hájková, P.; Pertoldi, C.; Ukendt, Zemanová

2007-01-01

Over the latter part of the 20th century, Eurasian otter Lutra lutra populations suffered dramatic declines, resulting in extinction or fragmentation of populations in many western and central European countries. Part of the Czech otter population became totally isolated while the Slovak populati...... that they remain a strongly protected species in both countries. The spreading and re-connection of otter populations observed recently is essential for the future health of the populations, and should be supported through habitat conservation......., suggesting that the strongest decline probably occurred between the 1970s and the mid-1990s. The results of this study confirm that otter populations remain vulnerable to any violent demographic change and, despite the claims of fish-farmers and anglers for legal culls, it is highly desirable...

Climate change, multiple stressors, and the decline of ectotherms.

Science.gov (United States)

Rohr, Jason R; Palmer, Brent D

2013-08-01

and may facilitate population declines of amphibians and perhaps other ectothermic vertebrates. © 2013 Society for Conservation Biology.

Inter-annual variability and long-term trends in breeding success in a declining population of migratory swans.

NARCIS (Netherlands)

Wood, K.A.; Newth, J.L.; Hilton, G.M.; Nolet, B.A.; Rees, E.C.

2016-01-01

Population declines among migratory Arctic-breeding birds are a growing concern for conservationists. To inform the conservation of these declining populations, we need to understand how demographic rates such as breeding success are influenced by combinations of extrinsic and intrinsic factors. In

Seasonal Variation in Population Abundance and Chytrid Infection in Stream-Dwelling Frogs of the Brazilian Atlantic Forest.

Directory of Open Access Journals (Sweden)

Joice Ruggeri

Full Text Available Enigmatic amphibian declines were first reported in southern and southeastern Brazil in the late 1980s and included several species of stream-dwelling anurans (families Hylodidae and Cycloramphidae. At that time, we were unaware of the amphibian-killing fungus Batrachochytrium dendrobatidis (Bd; therefore, pollution, habitat loss, fragmentation and unusual climatic events were hypothesized as primary causes of these declines. We now know that multiple lineages of Bd have infected amphibians of the Brazilian Atlantic forest for over a century, yet declines have not been associated specifically with Bd outbreaks. Because stream-dwelling anurans occupy an environmental hotspot ideal for disease transmission, we investigated temporal variation in population and infection dynamics of three stream-adapted species (Hylodes asper, H. phyllodes, and Cycloramphus boraceiensis on the northern coast of São Paulo state, Brazil. We surveyed standardized transects along streams for four years, and show that fluctuations in the number of frogs correlate with specific climatic variables that also increase the likelihood of Bd infections. In addition, we found that Bd infection probability in C. boraceiensis, a nocturnal species, was significantly higher than in Hylodes spp., which are diurnal, suggesting that the nocturnal activity may either facilitate Bd zoospore transmission or increase susceptibility of hosts. Our findings indicate that, despite long-term persistence of Bd in Brazil, some hosts persist with seasonally variable infections, and thus future persistence in the face of climate change will depend on the relative effect of those changes on frog recruitment and pathogen proliferation.

EU protected area network did not prevent a country wide population decline in a threatened grassland bird

Directory of Open Access Journals (Sweden)

João P. Silva

2018-01-01

Full Text Available Background Few studies have assessed the effectiveness of the Protected Area networks on the conservation status of target species. Here, we assess the effectiveness of the Portuguese Natura 2000 (the European Union network of protected areas in maintaining a species included in the Annex I of the Bird Directive, namely the population of a priority farmland bird, the little bustard Tetrax tetrax. Methods We measured the effectiveness of the Natura 2000 by comparing population trends across time (2003–2006 and 2016 in 51 areas, 21 of which within 12 Special Protection Areas (SPA that were mostly designated for farmland bird conservation and another 30 areas without EU protection. Results Overall, the national population is estimated to have declined 49% over the last 10–14 years. This loss was found to be proportionally larger outside SPA (64% decline compared to losses within SPA (25% decline. However, the absolute male density decline was significantly larger within SPA . Discussion In spite of holding higher population densities and having prevented habitat loss, we conclude that Natura 2000 was not effective in buffering against the overall bustard population decline. Results show that the mere designation of SPA in farmland is not enough to secure species populations and has to be combined with agricultural policies and investment to maintain not only habitat availability but also habitat quality.

EU protected area network did not prevent a country wide population decline in a threatened grassland bird.

Science.gov (United States)

Silva, João P; Correia, Ricardo; Alonso, Hany; Martins, Ricardo C; D'Amico, Marcello; Delgado, Ana; Sampaio, Hugo; Godinho, Carlos; Moreira, Francisco

2018-01-01

Few studies have assessed the effectiveness of the Protected Area networks on the conservation status of target species. Here, we assess the effectiveness of the Portuguese Natura 2000 (the European Union network of protected areas) in maintaining a species included in the Annex I of the Bird Directive, namely the population of a priority farmland bird, the little bustard Tetrax tetrax . We measured the effectiveness of the Natura 2000 by comparing population trends across time (2003-2006 and 2016) in 51 areas, 21 of which within 12 Special Protection Areas (SPA) that were mostly designated for farmland bird conservation and another 30 areas without EU protection. Overall, the national population is estimated to have declined 49% over the last 10-14 years. This loss was found to be proportionally larger outside SPA (64% decline) compared to losses within SPA (25% decline). However, the absolute male density decline was significantly larger within SPA . In spite of holding higher population densities and having prevented habitat loss, we conclude that Natura 2000 was not effective in buffering against the overall bustard population decline. Results show that the mere designation of SPA in farmland is not enough to secure species populations and has to be combined with agricultural policies and investment to maintain not only habitat availability but also habitat quality.

[Jaws of amphibians and reptiles].

Science.gov (United States)

Tanimoto, Masahiro

2005-04-01

Big jaws of amphibians and reptiles are mainly treated in this article. In amphibians enlarged skulls are for the big jaw in contrast with human's skulls for the brain. For example, famous fossils of Homo diluvii testis are ones of salamanders in fact. In reptiles, mosasaur jaws and teeth and their ecology are introduced for instance.

Biodiversity and Ecology of Amphibians and Reptiles of the Kennedy Space Center: 1998 Close-Out Report to NASA

Science.gov (United States)

Sigel, Richard A.

1999-01-01

Since 1992, there have been researchers have been studying the population ecology and conservation biology of the amphibians and reptiles of the Kennedy Space Center (KSC) This research is an outgrowth of my Master's work in the late 1970's under Lew Ehrhart at UCF. The primary emphasis of our studies are (1) examination of long-term changes in the abundance of amphibians and reptile populations, (2) occurrence and effects of Upper Respiratory Tract Disease (URTD) in gopher tortoises (Gopherus polyphemus), and (3) ecological studies of selected species.

Amphibians and Reptiles of the state of Nuevo León, Mexico.

Science.gov (United States)

Lemos-Espinal, Julio A; Smith, Geoffrey R; Cruz, Alexander

2016-01-01

We compiled a check list of the herpetofauna of Nuevo León. We documented 132 species (23 amphibians, 109 reptiles), representing 30 families (11 amphibians, 19 reptiles) and 73 genera (17 amphibians, 56 reptiles). Only two species are endemic to Nuevo León. Nuevo León contains a relatively high richness of lizards in the genus Sceloporus. Overlap in the herpetofauna of Nuevo León and states it borders is fairly extensive. Of 130 native species, 102 are considered species of Least Concern in the IUCN red list, four are listed as Vulnerable, five are listed as Near Threatened, and four are listed as Endangered. According to SEMARNAT, 78 species are not of conservation concern, 25 are subject to Special Protection, 27 are Threatened, and none are listed as in Danger of Extinction. Given current threats to the herpetofauna, additional efforts to understand the ecology and status of populations in Nuevo León are needed.

The North American Amphibian Monitoring Program. [abstract

Science.gov (United States)

Griffin, J.

1998-01-01

The North American Amphibian Monitoring Program has been under development for the past three years. The monitoring strategy for NAAMP has five main prongs: terrestrial salamander surveys, calling surveys, aquatic surveys, western surveys, and atlassing. Of these five, calling surveys were selected as one of the first implementation priorities due to their friendliness to volunteers of varying knowledge levels, relative low cost, and the fact that several groups had already pioneered the techniques involved. While some states and provinces had implemented calling surveys prior to NAAMP, like WI and IL, most states and provinces had little or no history of state/provincewide amphibian monitoring. Thus, the majority of calling survey programs were initiated in the past two years. To assess the progress of this pilot phase, a program review was conducted on the status of the NAAMP calling survey program, and the results of that review will be presented at the meeting. Topics to be discussed include: who is doing what where, extent of route coverage, the continuing random route discussions, quality assurance, strengths and weaknesses of calling surveys, reliability of data, and directions for the future. In addition, a brief overview of the DISPro project will be included. DISPro is a new amphibian monitoring program in National Parks, funded by the Demonstration of Intensive Sites Program (DISPro) through the EPA and NPS. It will begin this year at Big Bend and Shenandoah National Parks. The purpose of the DISPro Amphibian Project will be to investigate relationships between environmental factors and stressors and the distribution, abundance, and health of amphibians in these National Parks. At each Park, amphibian long-term monitoring protocols will be tested, distributions and abundance of amphibians will be mapped, and field research experiments will be conducted to examine stressor effects on amphibians (e.g., ultraviolet radiation, contaminants, acidification).

Validity of fish, birds and mammals as surrogates for amphibians and reptiles in pesticide toxicity assessment.

Science.gov (United States)

Ortiz-Santaliestra, Manuel E; Maia, Joao P; Egea-Serrano, Andrés; Lopes, Isabel

2018-02-28

Amphibians and reptiles are the two most endangered groups of vertebrates. Environmental pollution by pesticides is recognised as one of the major factors threatening populations of these groups. However, the effects of pesticides on amphibians and reptiles have been studied for few substances, which is partly related to the fact that these animals are not included in the mandatory toxicity testing conducted as part of environmental risk assessments of pesticides. Whether risks of pesticides to amphibians and reptiles are addressed by surrogate taxa used in risk assessment is currently under debate. In order to develop a scientifically sound and robust risk assessment scheme, information needs to be gathered to examine whether fish, birds and mammals are valid surrogates for amphibians and reptiles. We updated a systematic review of scientific literature that was recently published compiling toxicity data on amphibians and reptiles. The outcome of this review was analysed with the purposes to (1) compare endpoints from amphibians and reptiles with the available information from fish, birds and mammals, and (2) develop species sensitivity distributions (SSDs) for those substances tested in at least six amphibian species (no substances were found tested in at least six reptile species) to identify a candidate amphibian model species to be used as surrogate in risk assessment. A positive correlation was found between toxicity recorded on fish and amphibians, the former revealing, in general, to be more sensitive than the latter to waterborne pollutants. In the terrestrial environment, although birds and mammals were more sensitive than amphibians and reptiles to at least 60% of tested substances, just a few weak significant correlations were observed. As a general rule, homoeothermic vertebrates are not good surrogates for reptiles and terrestrial amphibians in pesticide risk assessment. However, some chemical-dependent trends were detected, with pyrethroids and

Assessing DNA Barcodes for Species Identification in North American Reptiles and Amphibians in Natural History Collections.

Science.gov (United States)

Chambers, E Anne; Hebert, Paul D N

2016-01-01

High rates of species discovery and loss have led to the urgent need for more rapid assessment of species diversity in the herpetofauna. DNA barcoding allows for the preliminary identification of species based on sequence divergence. Prior DNA barcoding work on reptiles and amphibians has revealed higher biodiversity counts than previously estimated due to cases of cryptic and undiscovered species. Past studies have provided DNA barcodes for just 14% of the North American herpetofauna, revealing the need for expanded coverage. This study extends the DNA barcode reference library for North American herpetofauna, assesses the utility of this approach in aiding species delimitation, and examines the correspondence between current species boundaries and sequence clusters designated by the BIN system. Sequences were obtained from 730 specimens, representing 274 species (43%) from the North American herpetofauna. Mean intraspecific divergences were 1% and 3%, while average congeneric sequence divergences were 16% and 14% in amphibians and reptiles, respectively. BIN assignments corresponded with current species boundaries in 79% of amphibians, 100% of turtles, and 60% of squamates. Deep divergences (>2%) were noted in 35% of squamate and 16% of amphibian species, and low divergences (reptiles and 23% of amphibians, patterns reflected in BIN assignments. Sequence recovery declined with specimen age, and variation in recovery success was noted among collections. Within collections, barcodes effectively flagged seven mislabeled tissues, and barcode fragments were recovered from five formalin-fixed specimens. This study demonstrates that DNA barcodes can effectively flag errors in museum collections, while BIN splits and merges reveal taxa belonging to deeply diverged or hybridizing lineages. This study is the first effort to compile a reference library of DNA barcodes for herpetofauna on a continental scale.

Effects of an invasive plant, Chinese tallow (Triadica sebifera), on development and survival of anuran larvae

Science.gov (United States)

Taylor B. Cotten; Matthew A. Kwiatkowski; Daniel Saenz; Michael Collyer

2012-01-01

Amphibians are considered one of the most threatened vertebrate groups. Although numerous studies have addressed the many causes of amphibian population decline, little is known about effects of invasive plants. Chinese tallow (Triadica sebifera) is an exotic deciduous tree that has invaded the southeastern United States. Amphibian larvae in environments invaded by T....

Colloquium paper: are we in the midst of the sixth mass extinction? A view from the world of amphibians.

Science.gov (United States)

Wake, David B; Vredenburg, Vance T

2008-08-12

Many scientists argue that we are either entering or in the midst of the sixth great mass extinction. Intense human pressure, both direct and indirect, is having profound effects on natural environments. The amphibians--frogs, salamanders, and caecilians--may be the only major group currently at risk globally. A detailed worldwide assessment and subsequent updates show that one-third or more of the 6,300 species are threatened with extinction. This trend is likely to accelerate because most amphibians occur in the tropics and have small geographic ranges that make them susceptible to extinction. The increasing pressure from habitat destruction and climate change is likely to have major impacts on narrowly adapted and distributed species. We show that salamanders on tropical mountains are particularly at risk. A new and significant threat to amphibians is a virulent, emerging infectious disease, chytridiomycosis, which appears to be globally distributed, and its effects may be exacerbated by global warming. This disease, which is caused by a fungal pathogen and implicated in serious declines and extinctions of >200 species of amphibians, poses the greatest threat to biodiversity of any known disease. Our data for frogs in the Sierra Nevada of California show that the fungus is having a devastating impact on native species, already weakened by the effects of pollution and introduced predators. A general message from amphibians is that we may have little time to stave off a potential mass extinction.

Conservation genetics and genomics of amphibians and reptiles.

Science.gov (United States)

Shaffer, H Bradley; Gidiş, Müge; McCartney-Melstad, Evan; Neal, Kevin M; Oyamaguchi, Hilton M; Tellez, Marisa; Toffelmier, Erin M

2015-01-01

Amphibians and reptiles as a group are often secretive, reach their greatest diversity often in remote tropical regions, and contain some of the most endangered groups of organisms on earth. Particularly in the past decade, genetics and genomics have been instrumental in the conservation biology of these cryptic vertebrates, enabling work ranging from the identification of populations subject to trade and exploitation, to the identification of cryptic lineages harboring critical genetic variation, to the analysis of genes controlling key life history traits. In this review, we highlight some of the most important ways that genetic analyses have brought new insights to the conservation of amphibians and reptiles. Although genomics has only recently emerged as part of this conservation tool kit, several large-scale data sources, including full genomes, expressed sequence tags, and transcriptomes, are providing new opportunities to identify key genes, quantify landscape effects, and manage captive breeding stocks of at-risk species.

Nothing a hot bath won't cure: infection rates of amphibian chytrid fungus correlate negatively with water temperature under natural field settings.

Science.gov (United States)

Forrest, Matthew J; Schlaepfer, Martin A

2011-01-01

Dramatic declines and extinctions of amphibian populations throughout the world have been associated with chytridiomycosis, an infectious disease caused by the pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd). Previous studies indicated that Bd prevalence correlates with cooler temperatures in the field, and laboratory experiments have demonstrated that Bd ceases growth at temperatures above 28°C. Here we investigate how small-scale variations in water temperature correlate with Bd prevalence in the wild. We sampled 221 amphibians, including 201 lowland leopard frogs (Rana [Lithobates] yavapaiensis), from 12 sites in Arizona, USA, and tested them for Bd. Amphibians were encountered in microhabitats that exhibited a wide range of water temperatures (10-50°C), including several geothermal water sources. There was a strong inverse correlation between the water temperature in which lowland leopard frogs were captured and Bd prevalence, even after taking into account the influence of year, season, and host size. In locations where Bd was known to be present, the prevalence of Bd infections dropped from 75-100% in water 30°C. A strong inverse correlation between Bd infection status and water temperature was also observed within sites. Our findings suggest that microhabitats where water temperatures exceed 30°C provide lowland leopard frogs with significant protection from Bd, which could have important implications for disease dynamics, as well as management applications.There must be quite a few things a hot bath won't cure, but I don't know many of them--Sylvia Plath, "The Bell Jar" (1963).

Nothing a hot bath won't cure: infection rates of amphibian chytrid fungus correlate negatively with water temperature under natural field settings.

Directory of Open Access Journals (Sweden)

Matthew J Forrest

Full Text Available Dramatic declines and extinctions of amphibian populations throughout the world have been associated with chytridiomycosis, an infectious disease caused by the pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd. Previous studies indicated that Bd prevalence correlates with cooler temperatures in the field, and laboratory experiments have demonstrated that Bd ceases growth at temperatures above 28°C. Here we investigate how small-scale variations in water temperature correlate with Bd prevalence in the wild. We sampled 221 amphibians, including 201 lowland leopard frogs (Rana [Lithobates] yavapaiensis, from 12 sites in Arizona, USA, and tested them for Bd. Amphibians were encountered in microhabitats that exhibited a wide range of water temperatures (10-50°C, including several geothermal water sources. There was a strong inverse correlation between the water temperature in which lowland leopard frogs were captured and Bd prevalence, even after taking into account the influence of year, season, and host size. In locations where Bd was known to be present, the prevalence of Bd infections dropped from 75-100% in water 30°C. A strong inverse correlation between Bd infection status and water temperature was also observed within sites. Our findings suggest that microhabitats where water temperatures exceed 30°C provide lowland leopard frogs with significant protection from Bd, which could have important implications for disease dynamics, as well as management applications.There must be quite a few things a hot bath won't cure, but I don't know many of them--Sylvia Plath, "The Bell Jar" (1963.

Louisiana ESI: REPTILES (Reptile and Amphibian Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for reptiles and amphibians in coastal Louisiana. Vector polygons represent reptile and amphibian habitats,...

Development and characterization of a model system to study amphibian immune responses to iridoviruses

International Nuclear Information System (INIS)

Gantress, Jennifer; Maniero, Gregory D.; Cohen, Nicholas; Robert, Jacques

2003-01-01

The recent realization that viruses within the family Iridoviridae may contribute to the worldwide decline in amphibians makes it urgent to understand amphibian antiviral immune defenses. We present evidence that establishes the frog Xenopus laevis as an important model with which to study anti-iridovirus immunity. Adults resist high doses of FV3 infection, showing only transitory signs of pathology. By contrast, naturally MHC class-I-deficient tadpoles are highly susceptible to FV3 infection. Monitoring of viral DNA by PCR indicates a preferential localization of FV3 DNA in the kidney, with the inbred MHC homozygous J strain appearing to be more susceptible. Clearance of virus as measured by detection of FV3 DNA and also the disappearance of pathological and behavioral symptoms of infection, acceleration of viral clearance, and detection of IgY anti-FV3 antibodies after a second injection of FV3 are all consistent with the involvement of both cellular and humoral adaptive antiviral immune responses

Epizootic to enzootic transition of a fungal disease in tropical Andean frogs: Are surviving species still susceptible?

Directory of Open Access Journals (Sweden)

Alessandro Catenazzi

Full Text Available The fungal pathogen Batrachochytrium dendrobatidis (Bd, which causes the disease chytridiomycosis, has been linked to catastrophic amphibian declines throughout the world. Amphibians differ in their vulnerability to chytridiomycosis; some species experience epizootics followed by collapse while others exhibit stable host/pathogen dynamics where most amphibian hosts survive in the presence of Bd (e.g., in the enzootic state. Little is known about the factors that drive the transition between the two disease states within a community, or whether populations of species that survived the initial epizootic are stable, yet this information is essential for conservation and theory. Our study focuses on a diverse Peruvian amphibian community that experienced a Bd-caused collapse. We explore host/Bd dynamics of eight surviving species a decade after the mass extinction by using population level disease metrics and Bd-susceptibility trials. We found that three of the eight species continue to be susceptible to Bd, and that their populations are declining. Only one species is growing in numbers and it was non-susceptible in our trials. Our study suggests that some species remain vulnerable to Bd and exhibit ongoing population declines in enzootic systems where Bd-host dynamics are assumed to be stable.

Amphibians and reptiles of the state of Hidalgo, Mexico

OpenAIRE

Lemos-Espinal, Julio; Smith, Geoffrey

2015-01-01

We compiled a checklist of the amphibians and reptiles of the state of Hidalgo, Mexico. The herpetofauna of Hidalgo consists of a total of 175 species: 54 amphibians (14 salamanders and 40 anurans); and 121 reptiles (one crocodile, five turtles, 36 lizards, 79 snakes). These taxa represent 32 families (12 amphibian families, 20 reptile families) and 87 genera (24 amphibian genera, 63 reptile genera). Two of these species are non-native species (Hemidactylus frenatus Duméril and Bibron, 1836 a...

Interactions of an insecticide, herbicide, and natural stressors in amphibian community mesocosms

Science.gov (United States)

Boone, M.D.; James, S.M.

2003-01-01

Amphibians developing in wetlands embedded within or near agricultural lands may frequently encounter chemical mixtures. The objectives of our study were to determine the effects that post-application concentrations of an insecticide (carbaryl) and an herbicide (atrazine) have on body mass, development, and survival of two anuran species (southern leopard frog, Rana sphenocephala; American toad, Bufo americanus) and two caudate species (spotted salamander, Ambystoma maculatum; small-mouthed salamander, A. texanum) reared in outdoor cattle tank mesocosms. In one experiment, we manipulated tadpole density (low or high), carbaryl exposure (0, 3.5, 7.0 mg/L), and atrazine exposure (0 or 200 μg/L) to test for effects on development, mass, and survival of larvae. In a second experiment, we manipulated pond hydroperiod (constant or drying), carbaryl exposure (0 or 5 mg/L), and atrazine exposure (0 or 200 μg/L) to test for effects on mass, time, and survival to metamorphosis. Salamanders were virtually eliminated in carbaryl treatments, indicating that at realistic levels, this insecticide could cause population declines for salamanders in contaminated habitats. Carbaryl also had negative effects on toad survival. Exposure to atrazine had negative effects on body size, development, and time to metamorphosis in anuran species, which were associated with reduced chlorophyll levels. Both chemicals interacted significantly with density or hydroperiod, indicating that the environmental conditions could influence the impact of a contaminant. A significant atrazine-by-carbaryl interaction resulted in smaller and less developed spotted salamander larvae than in control ponds. Atrazine exposure, however, appeared to moderate negative effects of carbaryl for spotted salamanders. Our research suggests that important changes in the community's food web result from chemical exposure, which influence the susceptibility of amphibian species to contaminants.

Phylogenetic analysis of algal symbionts associated with four North American amphibian egg masses.

Science.gov (United States)

Kim, Eunsoo; Lin, Yuan; Kerney, Ryan; Blumenberg, Lili; Bishop, Cory

2014-01-01

Egg masses of the yellow-spotted salamander Ambystoma maculatum form an association with the green alga "Oophila amblystomatis" (Lambert ex Wille), which, in addition to growing within individual egg capsules, has recently been reported to invade embryonic tissues and cells. The binomial O. amblystomatis refers to the algae that occur in A. maculatum egg capsules, but it is unknown whether this population of symbionts constitutes one or several different algal taxa. Moreover, it is unknown whether egg masses across the geographic range of A. maculatum, or other amphibians, associate with one or multiple algal taxa. To address these questions, we conducted a phylogeographic study of algae sampled from egg capsules of A. maculatum, its allopatric congener A. gracile, and two frogs: Lithobates sylvatica and L. aurora. All of these North American amphibians form associations with algae in their egg capsules. We sampled algae from egg capsules of these four amphibians from localities across North America, established representative algal cultures, and amplified and sequenced a region of 18S rDNA for phylogenetic analysis. Our combined analysis shows that symbiotic algae found in egg masses of four North American amphibians are closely related to each other, and form a well-supported clade that also contains three strains of free-living chlamydomonads. We designate this group as the 'Oophila' clade, within which the symbiotic algae are further divided into four distinct subclades. Phylogenies of the host amphibians and their algal symbionts are only partially congruent, suggesting that host-switching and co-speciation both play roles in their associations. We also established conditions for isolating and rearing algal symbionts from amphibian egg capsules, which should facilitate further study of these egg mass specialist algae.

Phylogenetic analysis of algal symbionts associated with four North American amphibian egg masses.

Directory of Open Access Journals (Sweden)

Eunsoo Kim

Full Text Available Egg masses of the yellow-spotted salamander Ambystoma maculatum form an association with the green alga "Oophila amblystomatis" (Lambert ex Wille, which, in addition to growing within individual egg capsules, has recently been reported to invade embryonic tissues and cells. The binomial O. amblystomatis refers to the algae that occur in A. maculatum egg capsules, but it is unknown whether this population of symbionts constitutes one or several different algal taxa. Moreover, it is unknown whether egg masses across the geographic range of A. maculatum, or other amphibians, associate with one or multiple algal taxa. To address these questions, we conducted a phylogeographic study of algae sampled from egg capsules of A. maculatum, its allopatric congener A. gracile, and two frogs: Lithobates sylvatica and L. aurora. All of these North American amphibians form associations with algae in their egg capsules. We sampled algae from egg capsules of these four amphibians from localities across North America, established representative algal cultures, and amplified and sequenced a region of 18S rDNA for phylogenetic analysis. Our combined analysis shows that symbiotic algae found in egg masses of four North American amphibians are closely related to each other, and form a well-supported clade that also contains three strains of free-living chlamydomonads. We designate this group as the 'Oophila' clade, within which the symbiotic algae are further divided into four distinct subclades. Phylogenies of the host amphibians and their algal symbionts are only partially congruent, suggesting that host-switching and co-speciation both play roles in their associations. We also established conditions for isolating and rearing algal symbionts from amphibian egg capsules, which should facilitate further study of these egg mass specialist algae.

Countryside biogeography of Neotropical reptiles and amphibians.

Science.gov (United States)

Mendenhall, Chase D; Frishkoff, Luke O; Santos-Barrera, Georgina; Pacheco, Jesús; Mesfun, Eyobed; Mendoza Quijano, Fernando; Ehrlich, Paul R; Ceballos, Gerardo; Daily, Gretchen C; Pringle, Robert M

2014-04-01

The future of biodiversity and ecosystem services depends largely on the capacity of human-dominated ecosystems to support them, yet this capacity remains largely unknown. Using the framework of countryside biogeography, and working in the Las Cruces system of Coto Brus, Costa Rica, we assessed reptile and amphibian assemblages within four habitats that typify much of the Neotropics: sun coffee plantations (12 sites), pasture (12 sites), remnant forest elements (12 sites), and a larger, contiguous protected forest (3 sites in one forest). Through analysis of 1678 captures of 67 species, we draw four primary conclusions. First, we found that the majority of reptile (60%) and amphibian (70%) species in this study used an array of habitat types, including coffee plantations and actively grazed pastures. Second, we found that coffee plantations and pastures hosted rich, albeit different and less dense, reptile and amphibian biodiversity relative to the 326-ha Las Cruces Forest Reserve and neighboring forest elements. Third, we found that the small ribbons of "countryside forest elements" weaving through farmland collectively increased the effective size of a 326-ha local forest reserve 16-fold for reptiles and 14-fold for amphibians within our 236-km2 study area. Therefore, countryside forest elements, often too small for most remote sensing techniques to identify, are contributing -95% of the available habitat for forest-dependent reptiles and amphibians in our largely human-dominated study region. Fourth, we found large and pond-reproducing amphibians to prefer human-made habitats, whereas small, stream-reproducing, and directly developing species are more dependent on forest elements. Our investigation demonstrates that tropical farming landscapes can support substantial reptile and amphibian biodiversity. Our approach provides a framework for estimating the conservation value of the complex working landscapes that constitute roughly half of the global land surface

Pentastomiasis and other parasitic zoonoses from reptiles and amphibians.

Science.gov (United States)

Pantchev, Nikola; Tappe, Dennis

2011-01-01

Reptiles are growing in popularity as pets.The colonization of reptiles and amphibians by parasites and the resulting disease conditions are the most common problems seen in captive animals.This review focuses on pentastomiasis and sparganosis, important parasitic zoonoses of reptiles and amphibians, respectively, and free living-amoebae. Humans are suitable accidental hosts for some pentastomid species (particularly Armillifer and Porocephalus). In geographical areas with special ethnics, such as in West and Central Africa, and East Asia, 8-45% of the human population can be affected. Usually the larvae are coincidentally found during abdominal surgeries. However, fatalities have been described. Extreme caution is necessary when handling infected reptiles. Ocular or cerebral sparganosis is not uncommonly found in humans in East Asia. This disease is caused by spargana, tapeworm larvae (plerocercoids) of Spirometra sp. The infection occurs when uncooked meat from reptiles or amphibians is applied to wounds or eyes and the parasites migrate directly to human tissue, or by consumption of contaminated food or water. As a consequence of the reptile's predatory behaviour, the full spectrum of endo- and ectoparasites from potential prey animals can be found as transiting parasites in the intestinal tract, e. g. Hymenolepis nana, Cryptosporidium (C.) muris, C parvum or Capillaria hepatica. Occasionally, free-living amoebae are also found in reptile faeces (Acanthamoeba, Naegleria, Hartmanella, Vahlkampfia or Echinamoeba sp.).

Are we in the midst of the sixth mass extinction? A view from the world of amphibians

Science.gov (United States)

Wake, David B.; Vredenburg, Vance T.

2008-01-01

Many scientists argue that we are either entering or in the midst of the sixth great mass extinction. Intense human pressure, both direct and indirect, is having profound effects on natural environments. The amphibians—frogs, salamanders, and caecilians—may be the only major group currently at risk globally. A detailed worldwide assessment and subsequent updates show that one-third or more of the 6,300 species are threatened with extinction. This trend is likely to accelerate because most amphibians occur in the tropics and have small geographic ranges that make them susceptible to extinction. The increasing pressure from habitat destruction and climate change is likely to have major impacts on narrowly adapted and distributed species. We show that salamanders on tropical mountains are particularly at risk. A new and significant threat to amphibians is a virulent, emerging infectious disease, chytridiomycosis, which appears to be globally distributed, and its effects may be exacerbated by global warming. This disease, which is caused by a fungal pathogen and implicated in serious declines and extinctions of >200 species of amphibians, poses the greatest threat to biodiversity of any known disease. Our data for frogs in the Sierra Nevada of California show that the fungus is having a devastating impact on native species, already weakened by the effects of pollution and introduced predators. A general message from amphibians is that we may have little time to stave off a potential mass extinction. PMID:18695221

Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline.

Science.gov (United States)

Bromaghin, Jeffrey F; Mcdonald, Trent L; Stirling, Ian; Derocher, Andrew E; Richardson, Evan S; Regehr, Eric V; Douglas, David C; Durner, George M; Atwood, Todd; Amstrup, Steven C

2015-04-01

In the southern Beaufort Sea of the United States and Canada, prior investigations have linked declines in summer sea ice to reduced physical condition, growth, and survival of polar bears (Ursus maritimus). Combined with projections of population decline due to continued climate warming and the ensuing loss of sea ice habitat, those findings contributed to the 2008 decision to list the species as threatened under the U.S. Endangered Species Act. Here, we used mark-recapture models to investigate the population dynamics of polar bears in the southern Beaufort Sea from 2001 to 2010, years during which the spatial and temporal extent of summer sea ice generally declined. Low survival from 2004 through 2006 led to a 25-50% decline in abundance. We hypothesize that low survival during this period resulted from (1) unfavorable ice conditions that limited access to prey during multiple seasons; and possibly, (2) low prey abundance. For reasons that are not clear, survival of adults and cubs began to improve in 2007 and abundance was comparatively stable from 2008 to 2010, with ~900 bears in 2010 (90% CI 606-1212). However, survival of subadult bears declined throughout the entire period. Reduced spatial and temporal availability of sea ice is expected to increasingly force population dynamics of polar bears as the climate continues to warm. However, in the short term, our findings suggest that factors other than sea ice can influence survival. A refined understanding of the ecological mechanisms underlying polar bear population dynamics is necessary to improve projections of their future status and facilitate development of management strategies.

Effects of pesticide exposure and the amphibian chytrid fungus on gray treefrog (Hyla chrysoscelis) metamorphosis.

Science.gov (United States)

Gaietto, Kristina M; Rumschlag, Samantha L; Boone, Michelle D

2014-10-01

Pesticides are detectable in most aquatic habitats and have the potential to alter host-pathogen interactions. The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), has been associated with amphibian declines around the world. However, Bd-associated declines are more prominent in some areas, despite nearly global distribution of Bd, suggesting other factors contribute to disease outbreaks. In a laboratory study, the authors examined the effects of 6 different isolates of Bd in the presence or absence of a pesticide (the insecticide carbaryl or the fungicide copper sulfate) to recently hatched Cope's gray treefrog (Hyla chrysoscelis) tadpoles reared through metamorphosis. The authors found the presence or absence of pesticides differentially altered the mass at metamorphosis of tadpoles exposed to different Bd isolates, suggesting that isolate could influence metamorphosis but not in ways expected based on origin of the isolate. Pesticide exposure had the strongest impact on metamorphosis of all treatment combinations. Whereas copper sulfate exposure reduced the length of the larval period, carbaryl exposure had apparent positive effects by increasing mass at metamorphosis and lengthening larval period, which adds to evidence that carbaryl can stimulate development in counterintuitive ways. The present study provides limited support to the hypothesis that pesticides can alter the response of tadpoles to isolates of Bd and that the insecticide carbaryl can alter developmental decisions. © 2014 SETAC.

Amphibian haematology: Metamorphosis-related changes in blood cells

DEFF Research Database (Denmark)

Rosenkilde, Per; Sørensen, Inger; Ussing, Anne Phaff

1995-01-01

Zoofysiologi, Amphibian metamorphosis, Haematology, Immunosuppression, Immunological Tolerance, Protozoan Infection, metamorfose, springpadder, ontogenese, halepadder.......Zoofysiologi, Amphibian metamorphosis, Haematology, Immunosuppression, Immunological Tolerance, Protozoan Infection, metamorfose, springpadder, ontogenese, halepadder....

Population and life-stage-specific effects of two herbicide formulations on the aquatic development of European common frogs (Rana temporaria).

Science.gov (United States)

Wagner, Norman; Veith, Michael; Lötters, Stefan; Viertel, Bruno

2017-01-01

Environmental contamination is suggested to contribute to amphibian population declines. However, the effects of a contaminant on a particular amphibian species can differ among populations. The authors investigated the toxic effects of 2 herbicide formulations on different populations and on representative developmental stages of the European common frog (Rana temporaria). Larvae from forest populations were more sensitive to a commonly used glyphosate-based herbicide compared with individuals from agrarian land. Median lethal concentrations correlated with measured glyphosate levels in the breeding ponds, which may be a sign of evolved tolerances. The reverse result was observed for a less commonly used cycloxydim-based herbicide. Effects of the glyphosate-based herbicide were stronger for earlier larval stages compared with later larval stages. Hence, applications in early spring (when early larvae are present in breeding ponds) pose greater risk concerning acute toxic effects on R. temporaria. With regard to late larval stages, short exposure (96 h) of prometamorphic larvae prolonged time to metamorphosis, but only at the highest test concentration that did not significantly induce mortality. This could be due to impairment of the thyroid axis. Notably, nearly all test concentrations of the 2 herbicides provoked growth retardation. Further research on how evolved or induced tolerances are acquired, actual contamination levels of amphibian habitats, and potential endocrine effects of glyphosate-based herbicides is necessary. Environ Toxicol Chem 2017;36:190-200. © 2016 SETAC. © 2016 SETAC.

Diseases of amphibian eggs and embryos

Science.gov (United States)

Green, D.E.; Converse, K.A.; Majumdar, S.K.; Huffman, J.E.; Brenner, F.J.; Panah, A.I.

2005-01-01

Amphibians generally are prolific egg producers. In tropical and semi-tropical regions, deposition of eggs may occur year-round or may coincide with rainy seasons, while in temperate regions, deposition of eggs usually occurs immediately after emergence from hibernation. Numbers of eggs produced by each species may vary from a few dozen to thousands. Accordingly, some eggs may be infertile and wastage of embryos is to be expected. Fertility, viability and decomposition of eggs and embryos must be considered before it is assumed that diseases are present. An important consideration in the evaluation of egg masses is the fact that some will contain infertile and non-viable eggs. These infertile and nonviable eggs will undergo decomposition and they may appear similar to eggs that are infected by a pathogen. Evaluation of egg masses and embryos for the presence of disease may require repeated observations in a given breeding season as well as continued monitoring of egg masses during their growth and development and over successive breeding seasons. Amphibian eggs rarely are subjected to a comprehensive health (diagnostic) examination; hence, there is scant literature on the diseases of this life stage. Indeed, the eggs of some North American amphibians have yet to be described. Much basic physiology and normal biomedical baseline data on amphibian eggs is lacking. For example, it is known that the aquatic eggs of some species of shrimp quickly are coated by a protective and commensal bacterium that effectively impedes invasion of the eggs by other environmental organisms and potential pathogens. In the absence of this bacterium, shrimp eggs are rapidly killed by other bacteria and fungi (Green, 2001). The possibility that amphibian eggs also have important symbiotic or commensal bacteria needs to be investigated. Furthermore, the quantity and types of chemicals in the normal gelatinous capsules of amphibian eggs have scarcely been examined. Abnormalities of the

Population growth and the decline of natural Southern yellow pine forests

Science.gov (United States)

David B. South; Edward R. Buckner

2004-01-01

Population growth has created social and economic pressures that affect the sustainability of naturally regenerated southern yellow pine forests. Major causes of this decline include (1) a shift in public attitudes regarding woods burning (from one favoring it to one that favors fire suppression) and (2) an increase in land values (especially near urban centers). The...

The demography of Atelopus decline: Harlequin frog survival and abundance in central Panama prior to and during a disease outbreak

Directory of Open Access Journals (Sweden)

Rebecca McCaffery

2015-07-01

Full Text Available Harlequin frogs (Bufonidae: Atelopus are a species-rich genus of Neotropical toads that have experienced disproportionately severe population declines and extinctions caused by the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd. The genus Atelopus is of high conservation concern, but relatively little is known about the population dynamics and life history of the majority of species. We examined the demography of one population of Atelopus zeteki and two populations of A. varius in central Panama using three to six years of mark-recapture data collected prior to and during an outbreak of Bd. We estimated male survival probabilities prior to the arrival of Bd and sex-specific population sizes for these three populations using state-space Bayesian population models. Prior to the arrival of Bd, monthly apparent survival probabilities were higher for A. varius males than for A. zeteki males, and recaptures among years were low in both species. Abundance of both species varied over time and declined rapidly after the arrival of Bd. Male densities were generally greater than female densities, though female densities were higher or equivalent to males after the arrival of Bd. Estimates of survival and abundance over time may be explained by differences in the use of stream habitat by the two sexes and three populations, both during and between breeding seasons. These estimates provide key baseline population information that can be used to inform reintroductions from captive assurance colonies and studies of extant Atelopus populations as part of conservation and management programs.

Predation of Ladybird Beetles (Coleoptera: Coccinellidae) by Amphibians.

Science.gov (United States)

Sloggett, John J

2012-07-18

Studies of predation of ladybird beetles (Coccinellidae) have focused on a limited number of predator taxa, such as birds and ants, while other potential predators have received limited attention. I here consider amphibians as predators of ladybirds. Published amphibian gut analyses show that ladybirds are quite often eaten by frogs and toads (Anura), with recorded frequencies reaching up to 15% of dietary items. Salamanders (Caudata) eat ladybirds less frequently, probably as their habits less often bring them into contact with the beetles. Amphibians do not appear to be deleteriously affected by the potentially toxic alkaloids that ladybirds possess. Amphibians, especially frogs and toads, use primarily prey movement as a release cue to attack their food; it is thus likely that their ability to discriminate against ladybirds and other chemically defended prey is limited. Because of this poor discriminatory power, amphibians have apparently evolved non-specific resistance to prey defensive chemicals, including ladybird alkaloids. Although amphibian-related ladybird mortality is limited, in certain habitats it could outweigh mortality from more frequently studied predators, notably birds. The gut analyses from the herpetological literature used in this study, suggest that in studying predation of insects, entomologists should consider specialized literature on other animal groups.

amphibian_biomarker_data

Data.gov (United States)

U.S. Environmental Protection Agency — Amphibian metabolite data used in Snyder, M.N., Henderson, W.M., Glinski, D.G., Purucker, S. T., 2017. Biomarker analysis of american toad (Anaxyrus americanus) and...

Using latent selection difference to model persistence in a declining population.

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Mara E Erickson

Full Text Available Population persistence is a direct measure of the viability of a population. Monitoring the distribution of declining populations or subpopulations over time can yield estimates of persistence, which we show can be modeled as a latent selection difference (LSD contrasting attributes of sites where populations have persisted versus those that have not. Predicted persistence can be modeled with predictor covariates to identify factors correlated with species persistence. We demonstrate how to model persistence based on changes in occupancy that can include adjustments for detection probability. Using a known historical distribution of the western grebe (Aechmophorus occidentalis, we adapted methods originally developed for occupancy modeling to evaluate how environmental covariates including emergent vegetation and human developments have affected western grebe persistence in Alberta. The relative probability of persistence was correlated with the extent of shoreline bulrush (Scirpus lacustris, which is important vegetation for nesting cover. We also documented that western grebe populations were less likely to persist on lakes in the boreal forest, primarily located on the northern boundary of the species' range. Factors influencing occupancy were different than those determining persistence by western grebes; persistence and occupancy were not correlated. Persistence was more likely on lakes with recreational development, reflecting reliance by grebes on the larger, fish-bearing waterbodies that also are attractive for lakeshore development. Unfortunately, the correlation with recreational development on Alberta's lakes puts grebes at risk for loss of brood-rearing habitats--primary threats to altricial birds--if steps are not taken to prevent disturbance to bulrush stands. Identifying factors related to the persistence of a species--especially one in decline--is a fundamental step in conservation management.

Sodium chloride inhibits the growth and infective capacity of the amphibian chytrid fungus and increases host survival rates.

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Michelle Pirrie Stockwell

Full Text Available The amphibian chytrid fungus Batrachochytrium dendrobatidis is a recently emerged pathogen that causes the infectious disease chytridiomycosis and has been implicated as a contributing factor in the global amphibian decline. Since its discovery, research has been focused on developing various methods of mitigating the impact of chytridiomycosis on amphibian hosts but little attention has been given to the role of antifungal agents that could be added to the host's environment. Sodium chloride is a known antifungal agent used routinely in the aquaculture industry and this study investigates its potential for use as a disease management tool in amphibian conservation. The effect of 0-5 ppt NaCl on the growth, motility and survival of the chytrid fungus when grown in culture media and its effect on the growth, infection load and survivorship of infected Peron's tree frogs (Litoria peronii in captivity, was investigated. The results reveal that these concentrations do not negatively affect the survival of the host or the pathogen. However, concentrations greater than 3 ppt significantly reduced the growth and motility of the chytrid fungus compared to 0 ppt. Concentrations of 1-4 ppt NaCl were also associated with significantly lower host infection loads while infected hosts exposed to 3 and 4 ppt NaCl were found to have significantly higher survival rates. These results support the potential for NaCl to be used as an environmentally distributed antifungal agent for the prevention of chytridiomycosis in susceptible amphibian hosts. However, further research is required to identify any negative effects of salt exposure on both target and non-target organisms prior to implementation.

Grassland Fire and Cattle Grazing Regulate Reptile and Amphibian Assembly Among Patches

Science.gov (United States)

Larson, Danelle M.

2014-12-01

Fire and grazing are common management schemes of grasslands globally and are potential drivers of reptilian and amphibian (herpetofauna) metacommunity dynamics. Few studies have assessed the impacts of fire and cattle grazing on herpetofauna assemblages in grasslands. A patch-burn grazing study at Osage Prairie, MO, USA in 2011-2012 created landscape patches with treatments of grazing, fire, and such legacies. Response variables were measured before and after the application of treatments, and I used robust-design occupancy modeling to estimate patch occupancy and detection rate within patches, and recolonization and extinction (i.e., dispersal) across patches. I conducted redundancy analysis and a permuted multivariate analysis of variance to determine if patch type and the associated environmental factors explained herpetofauna assemblage. Estimates for reptiles indicate that occupancy was seasonally constant in Control patches ( ψ ~ 0.5), but declined to ψ ~ 0.15 in patches following the applications of fire and grazing. Local extinctions for reptiles were higher in patches with fire or light grazing ( ɛ ~ 0.7) compared to the controls. For the riparian herpetofaunal community, patch type and grass height were important predictors of abundance; further, the turtles, lizards, snakes, and adult amphibians used different patch types. The aquatic amphibian community was predicted by watershed and in-stream characteristics, irrespective of fire or grazing. The varying responses from taxonomic groups demonstrate habitat partitioning across multiple patch types undergoing fire, cattle grazing, and legacy effects. Prairies will need an array of patch types to accommodate multiple herpetofauna species.

Short-term exposure to warm microhabitats could explain amphibian persistence with Batrachochytrium dendrobatidis.

Science.gov (United States)

Daskin, Joshua H; Alford, Ross A; Puschendorf, Robert

2011-01-01

Environmental conditions can alter the outcomes of symbiotic interactions. Many amphibian species have declined due to chytridiomycosis, caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd), but many others persist despite high Bd infection prevalence. This indicates that Bd's virulence is lower, or it may even be a commensal, in some hosts. In the Australian Wet Tropics, chytridiomycosis extirpated Litoria nannotis from high-elevation rain forests in the early 1990 s. Although the species is recolonizing many sites, no population has fully recovered. Litoria lorica disappeared from all known sites in the early 1990 s and was thought globally extinct, but a new population was discovered in 2008, in an upland dry forest habitat it shares with L. nannotis. All frogs of both species observed during three population censuses were apparently healthy, but most carried Bd. Frogs perch on sun-warmed rocks in dry forest streams, possibly keeping Bd infections below the lethal threshold attained in cooler rain forests. We tested whether short-term elevated temperatures can hamper Bd growth in vitro over one generation (four days). Simulating the temperatures available to frogs on strongly and moderately warmed rocks in dry forests, by incubating cultures at 33°C for one hour daily, reduced Bd growth below that of Bd held at 15°C constantly (representing rain forest habitats). Even small decreases in the exponential growth rate of Bd on hosts may contribute to the survival of frogs in dry forests.

Short-term exposure to warm microhabitats could explain amphibian persistence with Batrachochytrium dendrobatidis.

Directory of Open Access Journals (Sweden)

Joshua H Daskin

Full Text Available Environmental conditions can alter the outcomes of symbiotic interactions. Many amphibian species have declined due to chytridiomycosis, caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd, but many others persist despite high Bd infection prevalence. This indicates that Bd's virulence is lower, or it may even be a commensal, in some hosts. In the Australian Wet Tropics, chytridiomycosis extirpated Litoria nannotis from high-elevation rain forests in the early 1990 s. Although the species is recolonizing many sites, no population has fully recovered. Litoria lorica disappeared from all known sites in the early 1990 s and was thought globally extinct, but a new population was discovered in 2008, in an upland dry forest habitat it shares with L. nannotis. All frogs of both species observed during three population censuses were apparently healthy, but most carried Bd. Frogs perch on sun-warmed rocks in dry forest streams, possibly keeping Bd infections below the lethal threshold attained in cooler rain forests. We tested whether short-term elevated temperatures can hamper Bd growth in vitro over one generation (four days. Simulating the temperatures available to frogs on strongly and moderately warmed rocks in dry forests, by incubating cultures at 33°C for one hour daily, reduced Bd growth below that of Bd held at 15°C constantly (representing rain forest habitats. Even small decreases in the exponential growth rate of Bd on hosts may contribute to the survival of frogs in dry forests.

Global patterns of amphibian phylogenetic diversity

DEFF Research Database (Denmark)

Fritz, Susanne; Rahbek, Carsten

2012-01-01

Aim  Phylogenetic diversity can provide insight into how evolutionary processes may have shaped contemporary patterns of species richness. Here, we aim to test for the influence of phylogenetic history on global patterns of amphibian species richness, and to identify areas where macroevolutionary...... processes such as diversification and dispersal have left strong signatures on contemporary species richness. Location  Global; equal-area grid cells of approximately 10,000 km2. Methods  We generated an amphibian global supertree (6111 species) and repeated analyses with the largest available molecular...... phylogeny (2792 species). We combined each tree with global species distributions to map four indices of phylogenetic diversity. To investigate congruence between global spatial patterns of amphibian species richness and phylogenetic diversity, we selected Faith’s phylogenetic diversity (PD) index...

Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline

Science.gov (United States)

Bromaghin, Jeffrey F.; McDonald, Trent L.; Stirling, Ian; Derocher, Andrew E.; Richardson, Evan S.; Regehr, Eric V.; Douglas, David C.; Durner, George M.; Atwood, Todd C.; Amstrup, Steven C.

2015-01-01

In the southern Beaufort Sea of the United States and Canada, prior investigations have linked declines in summer sea ice to reduced physical condition, growth, and survival of polar bears (Ursus maritimus). Combined with projections of population decline due to continued climate warming and the ensuing loss of sea ice habitat, those findings contributed to the 2008 decision to list the species as threatened under the U.S. Endangered Species Act. Here, we used mark–recapture models to investigate the population dynamics of polar bears in the southern Beaufort Sea from 2001 to 2010, years during which the spatial and temporal extent of summer sea ice generally declined. Low survival from 2004 through 2006 led to a 25–50% decline in abundance. We hypothesize that low survival during this period resulted from (1) unfavorable ice conditions that limited access to prey during multiple seasons; and possibly, (2) low prey abundance. For reasons that are not clear, survival of adults and cubs began to improve in 2007 and abundance was comparatively stable from 2008 to 2010, with ~900 bears in 2010 (90% CI 606–1212). However, survival of subadult bears declined throughout the entire period. Reduced spatial and temporal availability of sea ice is expected to increasingly force population dynamics of polar bears as the climate continues to warm. However, in the short term, our findings suggest that factors other than sea ice can influence survival. A refined understanding of the ecological mechanisms underlying polar bear population dynamics is necessary to improve projections of their future status and facilitate development of management strategies.

[Historic record of Gastrotheca ovifera (Anura: Hemiphractidae): decline evidence in Venezuelan coastal cloud forests].

Science.gov (United States)

Valera-Leal, Javier; Acevedo, Aldemar; Pérez-Sánchez, Antonio; Vega, Jorge; Manzanilla, Jesús

2011-03-01

G. ovifera is a marsupial frog of the cloud and riparian forest from Western and Litoral sections of the Venezuelan Cordillera de la Costa (820-2 000m). This amphibian is considered as an endangered species by the IUCN Species Red List, due to its population decline in pristine and well preserved environments. This conservation status is based on anecdotic interpretations. We collected disperse data from museum records (national and international) and explored the possible association between collection records and precipitation data available for the Henri Pittier National Park (PNHP). Likewise, we carried out a systematic population monitoring of G. ovifera in historic and additional localities among the cloud forest of Rancho Grande, PNHP. We found 106 individuals in 11 zoological collections deposited during 1929-2007. After an effort of 646 hours/person we did not detect G. ovifera individuals in the evaluated localities; as well as no statistical significant associations between the annual precipitation average and the historic records of the species during 1941-1997 period (r = -0.054, p = 0.820, n = 19). We discussed the distribution, fluctuation and population changes of this species, analyzing it conservation status.

A fungal pathogen of amphibians, Batrachochytrium dendrobatidis, attenuates in pathogenicity with in vitro passages.

Science.gov (United States)

Langhammer, Penny F; Lips, Karen R; Burrowes, Patricia A; Tunstall, Tate; Palmer, Crystal M; Collins, James P

2013-01-01

Laboratory investigations into the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), have accelerated recently, given the pathogen's role in causing the global decline and extinction of amphibians. Studies in which host animals were exposed to Bd have largely assumed that lab-maintained pathogen cultures retained the infective and pathogenic properties of wild isolates. Attenuated pathogenicity is common in artificially maintained cultures of other pathogenic fungi, but to date, it is unknown whether, and to what degree, Bd might change in culture. We compared zoospore production over time in two samples of a single Bd isolate having different passage histories: one maintained in artificial media for more than six years (JEL427-P39), and one recently thawed from cryopreserved stock (JEL427-P9). In a common garden experiment, we then exposed two different amphibian species, Eleutherodactylus coqui and Atelopus zeteki, to both cultures to test whether Bd attenuates in pathogenicity with in vitro passages. The culture with the shorter passage history, JEL427-P9, had significantly greater zoospore densities over time compared to JEL427-P39. This difference in zoospore production was associated with a difference in pathogenicity for a susceptible amphibian species, indicating that fecundity may be an important virulence factor for Bd. In the 130-day experiment, Atelopus zeteki frogs exposed to the JEL427-P9 culture experienced higher average infection intensity and 100% mortality, compared with 60% mortality for frogs exposed to JEL427-P39. This effect was not observed with Eleutherodactylus coqui, which was able to clear infection. We hypothesize that the differences in phenotypic performance observed with Atelopus zeteki are rooted in changes of the Bd genome. Future investigations enabled by this study will focus on the underlying mechanisms of Bd pathogenicity.

A fungal pathogen of amphibians, Batrachochytrium dendrobatidis, attenuates in pathogenicity with in vitro passages.

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Penny F Langhammer

Full Text Available Laboratory investigations into the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd, have accelerated recently, given the pathogen's role in causing the global decline and extinction of amphibians. Studies in which host animals were exposed to Bd have largely assumed that lab-maintained pathogen cultures retained the infective and pathogenic properties of wild isolates. Attenuated pathogenicity is common in artificially maintained cultures of other pathogenic fungi, but to date, it is unknown whether, and to what degree, Bd might change in culture. We compared zoospore production over time in two samples of a single Bd isolate having different passage histories: one maintained in artificial media for more than six years (JEL427-P39, and one recently thawed from cryopreserved stock (JEL427-P9. In a common garden experiment, we then exposed two different amphibian species, Eleutherodactylus coqui and Atelopus zeteki, to both cultures to test whether Bd attenuates in pathogenicity with in vitro passages. The culture with the shorter passage history, JEL427-P9, had significantly greater zoospore densities over time compared to JEL427-P39. This difference in zoospore production was associated with a difference in pathogenicity for a susceptible amphibian species, indicating that fecundity may be an important virulence factor for Bd. In the 130-day experiment, Atelopus zeteki frogs exposed to the JEL427-P9 culture experienced higher average infection intensity and 100% mortality, compared with 60% mortality for frogs exposed to JEL427-P39. This effect was not observed with Eleutherodactylus coqui, which was able to clear infection. We hypothesize that the differences in phenotypic performance observed with Atelopus zeteki are rooted in changes of the Bd genome. Future investigations enabled by this study will focus on the underlying mechanisms of Bd pathogenicity.

Dry creek long-term watershed study: buffer zone performance as viable amphibian habitat

Science.gov (United States)

Brooke L. Talley; Thomas L. Crisman

2006-01-01

As bioindicators, amphibians typically require both terrestrial and aquatic habitats to complete their life cycles. Pre- timber-harvest monitoring (December 2002 through September 2003) of salamander and frog (Hylidae) populations was conducted in four watersheds of Decatur County, GA. Post- timber-harvest monitoring (December 2003 through September...

[The decline in population growth, income distribution, and economic recession].

Science.gov (United States)

Banguero, H

1983-05-01

This work uses Keynesian principles and an analysis of the Colombian population in the 1970s to argue that the Colombian policy of slowing population growth, which was adopted with the aim of improving the general welfare of the population, has had shortterm negative effects on effective demand and thus on the level of employment and welfare. These negative effects were caused by the inflexibility of income distribution, which prevented expansion of the internal market, complicated by the stagnant condition of the external sector and the budget deficit. The results of the Colombian case study demonstrate how the deceleration of population growth beginning in the 1960s had a significant impact on the levels of consumption and savings and on the patterns of consumption, leading to low levels of investment and little dynamism. Although the current Colombian economic recession is aggravated by contextual factors such as the world economic recession, the high cost of capital, the industrial recession, and declining food production among others, at the core of the crisis are longer term structural determinants such as the decline in the rate of population growth and the highly unequal distribution of income and wealth, which have contributed to a shrinking of the internal market for some types of goods. Given the unlikelihood of renewed rapid population growth, the Keynesian model suggests that the only alternative for increasing aggregate demand is state intervention through public spending and investment and reorientation of the financial system to achieve a dynamic redistribution of income. Based on these findings and on proposals of other analysts, a stragegy for revitalization is proposed which would imply a gradual income redistribution to allow increased consumption of mass produced goods by the low income groups. Direct consumption subsidies would be avoided because of their inflationary and import-expanding tendencies; rather, incentives and support would be

Red List of amphibians and reptiles of the Wadden Sea area

Science.gov (United States)

Fog, K.; Podloucky, R.; Dierking, U.; Stumpel, A. H. P.

1996-10-01

In the Wadden Sea, in total, 8 species of amphibians and 4 species of reptiles are threatened in at least one subregion. Of these, 7 species of amphibians and all 4 species of reptiles are threatened in the entire area and are therefore placed on the trilateral Red List. 1 species of the listed reptiles is (probably) extinct in the entire Wadden Sea area. The status of 1 species of amphibians is endangered, the status of (probably) 4 species of amphibians and 3 species of reptiles are vulnerable and of 2 species of amphibians susceptible.

Invasive and introduced reptiles and amphibians: Chapter 28

Science.gov (United States)

Reed, Robert N.; Krysko, Kenneth L.; Mader, Douglas R.; Divers, Stephen J.

2014-01-01

Why is there a section on introduced amphibians and reptiles in this volume, and why should veterinarians care about this issue? Globally, invasive species are a major threat to the stability of native ecosystems,1,2 and amphibians and reptiles are attracting increased attention as potential invaders. Some introduced amphibians and reptiles have had a major impact (e.g., Brown Tree Snakes [Boiga irregularis] wiping out the native birds of Guam3 or Cane Toads [Rhinella marina] poisoning native Australian predators).4 For the vast majority of species, however, the ecological, economic, and sociopolitical effects of introduced amphibians and reptiles are generally poorly quantified, largely because of a lack of focused research effort rather than because such effects are nonexistent. This trend is alarming given that rates of introduction have increased exponentially in recent decades.

Lion (Panthera leo) populations are declining rapidly across Africa, except in intensively managed areas

OpenAIRE

Bauer, Hans; Chapron, Guillaume; Nowell, Kristin; Henschel, Philipp; Funston, Paul; Hunter, Luke T. B.; Macdonald, David W.; Packer, Craig

2015-01-01

At a regional scale, lion populations in West, Central, and East Africa are likely to suffer a projected 50% decline over the next two decades, whereas lion populations are only increasing in southern Africa. Many lion populations are either now gone or expected to disappear within the next few decades to the extent that the intensively managed populations in southern Africa may soon supersede the iconic savannah landscapes in East Africa as the most successful sites for lion conservation. Th...

Effects of amphibian phylogeny, climate and human impact on the occurrence of the amphibian-killing chytrid fungus.

Science.gov (United States)

Bacigalupe, Leonardo D; Soto-Azat, Claudio; García-Vera, Cristobal; Barría-Oyarzo, Ismael; Rezende, Enrico L

2017-09-01

Chytridiomycosis, due to the fungus Batrachochytrium dendrobatidis (Bd), has been associated with the alarming decline and extinction crisis of amphibians worldwide. Because conservation programs are implemented locally, it is essential to understand how the complex interactions among host species, climate and human activities contribute to Bd occurrence at regional scales. Using weighted phylogenetic regressions and model selection, we investigated geographic patterns of Bd occurrence along a latitudinal gradient of 1500 km within a biodiversity hot spot in Chile (1845 individuals sampled from 253 sites and representing 24 species), and its association with climatic, socio-demographic and economic variables. Analyses show that Bd prevalence decreases with latitude although it has increased by almost 10% between 2008 and 2013, possibly reflecting an ongoing spread of Bd following the introduction of Xenopus laevis. Occurrence of Bd was higher in regions with high gross domestic product (particularly near developed centers) and with a high variability in rainfall regimes, whereas models including other bioclimatic or geographic variables, including temperature, exhibited substantially lower fit and virtually no support based on Akaike weights. In addition, Bd prevalence exhibited a strong phylogenetic signal, with five species having high numbers of infected individuals and higher prevalence than the average of 13.3% across all species. Taken together, our results highlight that Bd in Chile might still be spreading south, facilitated by a subset of species that seem to play an important epidemiological role maintaining this pathogen in the communities, in combination with climatic and human factors affecting the availability and quality of amphibian breeding sites. This information may be employed to design conservation strategies and mitigate the impacts of Bd in the biodiversity hot spot of southern Chile, and similar studies may prove useful to disentangle the

Diversity of Andean amphibians of the Tamá National Natural Park in Colombia: a survey for the presence of Batrachochytrium dendrobatidis

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Acevedo, A.A.; Franco, R.; Carrero, D.A.

2016-07-01

Changes in diversity and possible decreases in populations of amphibians have not yet been determined in many areas in the Andes. This study aimed to develop an inventory of the biodiversity of amphibians in the Andean areas of the Tamá National Natural Park (Tamá NNP) and to evaluate the patterns of infection by Batrachochytrium dendrobatidis (Bd) in preserved and degraded areas. We performed samplings focused on three habitats (forest, open areas and streams) in four localities from 2,000 to 3,200 m in altitude. Fourteen species were recorded, 12 of which were positive for Bd. A total of 541 individuals were diagnosed and 100 were positive. Our analyses showed that preserved areas play an important role in keeping many individuals Bd–free as compared to those in degraded areas. This was the first study to evaluate diversity and infection by Bd in the northeast region of Colombia. Our findings may help improve our knowledge of the diversity of amphibian species in the area and facilitate the implementation of action plans to mitigate the causes associated with the decrease in amphibian populations. (Author)

Evaluation of microorganisms cultured from injured and repressed tissue regeneration sites in endangered giant aquatic Ozark Hellbender salamanders.

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Cheryl A Nickerson

Full Text Available Investigation into the causes underlying the rapid, global amphibian decline provides critical insight into the effects of changing ecosystems. Hypothesized and confirmed links between amphibian declines, disease, and environmental changes are increasingly represented in published literature. However, there are few long-term amphibian studies that include data on population size, abnormality/injury rates, disease, and habitat variables to adequately assess changes through time. We cultured and identified microorganisms isolated from abnormal/injured and repressed tissue regeneration sites of the endangered Ozark Hellbender, Cryptobranchus alleganiensis bishopi, to discover potential causative agents responsible for their significant decline in health and population. This organism and our study site were chosen because the population and habitat of C. a. bishopi have been intensively studied from 1969-2009, and the abnormality/injury rate and apparent lack of regeneration were established. Although many bacterial and fungal isolates recovered were common environmental organisms, several opportunistic pathogens were identified in association with only the injured tissues of C.a. bishopi. Bacterial isolates included Aeromonas hydrophila, a known amphibian pathogen, Granulicetella adiacens, Gordonai terrae, Stenotrophomonas maltophilia, Aerococcus viridans, Streptococcus pneumoniae and a variety of Pseudomonads, including Pseudomonas aeruginosa, P. stutzeri, and P. alcaligenes. Fungal isolates included species in the genera Penicillium, Acremonium, Cladosporium, Curvularia, Fusarium, Streptomycetes, and the Class Hyphomycetes. Many of the opportunistic pathogens identified are known to form biofilms. Lack of isolation of the same organism from all wounds suggests that the etiological agent responsible for the damage to C. a. bishopi may not be a single organism. To our knowledge, this is the first study to profile the external microbial consortia

Long-term monitoring of an amphibian community after a climate change- and infectious disease-driven species extirpation.

Science.gov (United States)

Bosch, Jaime; Fernández-Beaskoetxea, Saioa; Garner, Trenton W J; Carrascal, Luis María

2018-02-15

Infectious disease and climate change are considered major threats to biodiversity and act as drivers behind the global amphibian decline. This is, to a large extent, based on short-term studies that are designed to detect the immediate and strongest biodiversity responses to a threatening process. What few long-term studies are available, although typically focused on single species, report outcomes that often diverge significantly from the short-term species responses. Here, we report the results of an 18-year survey of an amphibian community exposed to both climate warming and the emergence of lethal chytridiomycosis. Our study shows that the impacts of infectious disease are ongoing but restricted to two out of nine species that form the community, despite the fact all species can become infected with the fungus. Climate warming appears to be affecting four out of the nine species, but the response of three of these is an increase in abundance. Our study supports a decreasing role of infectious disease on the community, and an increasing and currently positive effect of climate warming. We caution that if the warming trends continue, the net positive effect will turn negative as amphibian breeding habitat becomes unavailable as water bodies dry, a pattern that already may be underway. © 2018 John Wiley & Sons Ltd.

Waist Circumference, Not Body Mass Index, Is Associated with Renal Function Decline in Korean Population: Hallym Aging Study

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Oh, Hyunju; Quan, Shan Ai; Jeong, Jin-Young; Jang, Soong-Nang; Lee, Jung Eun; Kim, Dong-Hyun

2013-01-01

Background Prospective investigation of obesity and renal function decline in Asia is sparse. We examined the associations of body mass index (BMI) and waist circumference (WC) with renal function decline in a prospective study of Korean population. Methods A total of 454 participants who had baseline estimated glomerular filtration rate (eGFR) levels of more than 60 mL/min/1.73 m2 in Hallym Aging Study (HAS) were included and followed for 6 years. Renal function decline was defined as follows: (1) an eGFR decline ≥3 mL/min/1.73 m2/year (n = 82 cases); (2) an eGFR decrease of 20% or greater (n = 87 cases) at follow-up; (3) an eGFR decrease of 20% greater at follow-up or eGFR decline ≥3 mL/min/1.73 m2/year (n = 91 cases); and (4) an eGFR 95 cm in men or >90 cm in women with ≤90 cm in men or ≤85 cm in women, ORs (95% CIs) ranged from 2.31 (1.14–4.69) to 2.78 (1.19–6.50) for the 4 definitions of renal function decline (all p-values for trend Korean population. Our results provide important evidence that simple measurement of central fat deposition rather than BMI could predict decline in renal function in Korean population. PMID:23536858

Non-native fish introductions and the decline of the mountain yellow-legged frog from within protected areas

Science.gov (United States)

R.A. Knapp; K.R. Matthews

2000-01-01

Abstract: One of the most puzzling aspects of the worldwide decline of amphibians is their disappearance from within protected areas. Because these areas are ostensibly undisturbed, habitat alterations are generally perceived as unlikely causes. The introduction of non-native fishes into protected areas, however, is a common practice throughout the world and may exert...

Swabbing often fails to detect amphibian Chytridiomycosis under conditions of low infection load.

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Jaehyub Shin

Full Text Available The pathogenic chytrid fungus, Batrachochytrium dendrobatidis (denoted Bd, causes large-scale epizootics in naïve amphibian populations. Intervention strategies to rapidly respond to Bd incursions require sensitive and accurate diagnostic methods. Chytridiomycosis usually is assessed by quantitative polymerase chain reaction (qPCR amplification of amphibian skin swabs. Results based on this method, however, sometimes yield inconsistent results on infection status and inaccurate scores of infection intensity. In Asia and other regions where amphibians typically bear low Bd loads, swab results are least reliable. We developed a Bd-sampling method that collects zoospores released by infected subjects into an aquatic medium. Bd DNA is extracted by filters and amplified by nested PCR. Using laboratory colonies and field populations of Bombina orientalis, we compare results with those obtained on the same subjects by qPCR of DNA extracted from swabs. Many subjects, despite being diagnosed as Bd-negative by conventional methods, released Bd zoospores into collection containers and thus must be considered infected. Infection loads determined from filtered water were at least 1000 times higher than those estimated from swabs. Subjects significantly varied in infection load, as they intermittently released zoospores, over a 5-day period. Thus, the method might be used to compare the infectivity of individuals and study the periodicity of zoospore release. Sampling methods based on water filtration can dramatically increase the capacity to accurately diagnose chytridiomycosis and contribute to a better understanding of the interactions between Bd and its hosts.

Thyroid Antibodies, Autoimmunity and Cognitive Decline: Is There a Population-Based Link

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Kate Napthali

2014-05-01

Full Text Available Background: Autoimmunity is considered an uncommon but under-recognised cause of cognitive decline. Methods: Serum samples from 3,253 randomly selected subjects enrolled in the Hunter Community Study, aged 55-85 years, were assayed for thyrotropin stimulatory hormone, anti-thyroid peroxidase antibodies (TPO-Ab, anti-nuclear antibodies (ANA and extractable nuclear antigens (ENA. Cognitive function was assessed using the Audio Recorded Cognitive Screen (ARCS tool. Results: TPO-Ab were found in 8.4% and ANA in 27.9% of the study population, of whom 3% had positive ENA findings. No relationship was found between the ARCS score and either TPO-Ab (coefficient = 0.133; 95% CI -0.20, 0.82, p = 0.616, ANA at a low (coefficient = 1.01; 95% CI -2.58, 0.55, p = 0.203 or a high titre (coefficient = -0.65; 95% CI -2.59, 1.28, p = 0.508, or ENA antibodies (coefficient = 5.12; 95% CI -0.53, 10.77; p = 0.076. Conclusions: Autoantibody findings are common in an aging population and are not associated with cognitive decline.

Attributing mortality among drivers of population decline in Acropora palmata in the Florida Keys (USA)

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Williams, D. E.; Miller, M. W.

2012-06-01

Acropora palmata populations have experienced steep declines over the past 30 years. Although numerous culprits are recognized, their relative contributions to the decline are poorly quantified, making it difficult to prioritize effective conservation measures. In 2004, a demographic monitoring program was implemented in the Florida Keys (USA), aimed at determining the relative importance of various stressors affecting A. palmata. A subset of randomly selected A. palmata colonies within 15 fore-reef plots was tagged and surveyed three to four times per year over 7 years. Colony size, live tissue, prevalence of disease, snail ( Coralliophila abbreviata) predation, physical damage and other conditions were assessed at each survey. The estimated effect of each condition causing recent mortality was ranked, and together, these parameters were used to attribute the population-level tissue loss associated with each condition. In addition, all new colonies in the study plots were counted and assessed annually in order to track trends in total colony count and live tissue abundance. Between 2004 and 2010, the study population has shown more than 50% decline in live area from three main conditions: fragmentation, disease and snail predation. Approximately half of this decline occurred during the catastrophic 2005 hurricane season from which recovery has been minimal. Meanwhile, colony abundance has shown gradual decline throughout the study. Snail predation was the most prevalent condition. However, it ranked third in attributed tissue loss, behind breakage that occurred during the 2005 hurricane season, and disease. Thermal bleaching of A. palmata was not observed during this study. Because mortality continues to outpace recruitment and growth, intervention to ameliorate losses to the more manageable threats including predation and breakage could result in substantial conservation of live tissue, buying time for the abatement of less tractable threats to A. palmata

Breeding season food limitation drives population decline of the Little Owl Athene noctua in Denmark

DEFF Research Database (Denmark)

Thorup, Kasper; Sunde, Peter; Jacobsen, Lars B.

2010-01-01

landscape, has declined over most of northwestern Europe, including Denmark. We investigated the likely reasons for the population decline in Denmark by identifying patterns of local extinction (scale, 5 x 5 km2) and estimating demographic parameters affecting local survival, focusing on changes over time...

Possibilties of using amphibians and reptiles to indicate environmental pollution

Energy Technology Data Exchange (ETDEWEB)

Petrov, V.S.; Sharygin, S.A.

1981-01-01

Data on the presence of certain toxic elements in organisms of amphibians and reptiles are reported. Differences in chemical composition of organisms of amphibians and reptiles living in wild biotopes and in settlements are shown. Analysis of microelement concentration in organisms of amphibians and reptiles can be used to detect pollution in urban areas.

Sperm motility of externally fertilizing fish and amphibians.

Science.gov (United States)

Browne, R K; Kaurova, S A; Uteshev, V K; Shishova, N V; McGinnity, D; Figiel, C R; Mansour, N; Agney, D; Wu, M; Gakhova, E N; Dzyuba, B; Cosson, J

2015-01-01

We review the phylogeny, sperm competition, morphology, physiology, and fertilization environments of the sperm of externally fertilizing fish and amphibians. Increased sperm competition in both fish and anurans generally increases sperm numbers, sperm length, and energy reserves. The difference between the internal osmolarity and iconicity of sperm cells and those of the aquatic medium control the activation, longevity, and velocity of sperm motility. Hypo-osmolarity of the aquatic medium activates the motility of freshwater fish and amphibian sperm and hyperosmolarity activates the motility of marine fish sperm. The average longevity of the motility of marine fish sperm (~550 seconds) was significantly (P amphibian sperm in general and anurans reversion from internal to external fertilization. Our findings provide a greater understanding of the reproductive biology of externally fertilizing fish and amphibians, and a biological foundation for the further development of reproduction technologies for their sustainable management.

Clear-cutting affects habitat connectivity for a forest amphibian by decreasing permeability to juvenile movements.

Science.gov (United States)

Popescu, Viorel D; Hunter, Malcolm L

2011-06-01

Conservation of forest amphibians is dependent on finding the right balance between management for timber production and meeting species' habitat requirements. For many pond-breeding amphibians, successful dispersal of the juvenile stage is essential for long-term population persistence. We investigated the influence of timber-harvesting practices on the movements of juvenile wood frogs (Lithobates sylvaticus). We used a chronosequence of stands produced by clear-cutting to evaluate how stand age affects habitat permeability to movements. We conducted experimental releases of juveniles in 2008 (n = 350) and 2009 (n = 528) in unidirectional runways in four treatments: mature forest, recent clearcut, 11-year-old, and 20-year-old regeneration. The runways were 50 x 2.5-m enclosures extending into each treatment, perpendicular to a distinct edge, with four tracking stations at 10, 20, 30, and 40 m from the edge. We recorded the number of animals reaching each tracking station, and the proportion of animals changing their direction of movement at each distance. We found that the mature forest was 3.1 and 3.7 times more permeable than the 11-year-old regeneration and the recent clearcut, respectively. Animals actively avoided open-canopy habitats and sharp edges; significantly more animals returned toward the closed-canopy forest at 0 m and 10 m in the less permeable treatments. There were no significant differences in habitat permeability between the mature forest and the 20-year-old regeneration. Our study is the first to directly assess habitat permeability to juvenile amphibian movement in relation to various forestry practices. We argue that habitat permeability at this scale is largely driven by the behavior of animals in relation to habitat disturbance and that caution needs to be used when using spatial modeling and expert-derived permeability values to assess connectivity of amphibian populations. The effects of clear-cutting on the migratory success of juvenile

Despite Buffers, Experimental Forest Clearcuts Impact Amphibian Body Size and Biomass.

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Veysey Powell, Jessica S; Babbitt, Kimberly J

2015-01-01

Forest buffers are a primary tool used to protect wetland-dependent wildlife. Though implemented widely, buffer efficacy is untested for most amphibian species. Consequently, it remains unclear whether buffers are sufficient for maintaining amphibian populations and if so, how wide buffers should be. We present evidence from a six-year, landscape-scale experiment testing the impacts of clearcutting, buffer width, and hydroperiod on body size and condition and biomass of breeding adults for two amphibian species at 11 vernal pools in the northeastern United States. We randomly assigned treatments (i.e., reference, 100m buffer, 30m buffer) across pools, clearcut to create buffers, and captured all spotted salamanders and wood frogs. Clearcuts strongly and negatively impacted size, condition, and biomass, but wider buffers mitigated effect magnitude and duration. Among recaptured individuals, for example, 30m-treatment salamanders were predicted to be about 9.5 mm shorter than, while 100m-treatment salamanders did not differ in length from, reference-treatment salamanders. Similarly, among recaptured frogs, mean length in the 30m treatment was predicted to decrease by about 1 mm/year, while in the 100m and reference treatments, length was time-invariant. Some, but not all, metrics recovered with time. For example, female new-captured and recaptured salamanders were predicted, respectively and on average, to weigh 4.5 and 7 g less in the 30m versus reference treatment right after the cut. While recaptured-female mass was predicted to recover by 9.5 years post-cut, new-captured-female mass did not recover. Hydroperiod was an important mediator: in the 100m treatment, cutting predominately affected pools that were stressed hydrologically. Overall, salamanders and female frogs were impacted more than male frogs. Our results highlight the importance of individualized metrics like body size, which can reveal sublethal effects and illuminate mechanisms by which habitat

Despite Buffers, Experimental Forest Clearcuts Impact Amphibian Body Size and Biomass.

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Jessica S Veysey Powell

Full Text Available Forest buffers are a primary tool used to protect wetland-dependent wildlife. Though implemented widely, buffer efficacy is untested for most amphibian species. Consequently, it remains unclear whether buffers are sufficient for maintaining amphibian populations and if so, how wide buffers should be. We present evidence from a six-year, landscape-scale experiment testing the impacts of clearcutting, buffer width, and hydroperiod on body size and condition and biomass of breeding adults for two amphibian species at 11 vernal pools in the northeastern United States. We randomly assigned treatments (i.e., reference, 100m buffer, 30m buffer across pools, clearcut to create buffers, and captured all spotted salamanders and wood frogs. Clearcuts strongly and negatively impacted size, condition, and biomass, but wider buffers mitigated effect magnitude and duration. Among recaptured individuals, for example, 30m-treatment salamanders were predicted to be about 9.5 mm shorter than, while 100m-treatment salamanders did not differ in length from, reference-treatment salamanders. Similarly, among recaptured frogs, mean length in the 30m treatment was predicted to decrease by about 1 mm/year, while in the 100m and reference treatments, length was time-invariant. Some, but not all, metrics recovered with time. For example, female new-captured and recaptured salamanders were predicted, respectively and on average, to weigh 4.5 and 7 g less in the 30m versus reference treatment right after the cut. While recaptured-female mass was predicted to recover by 9.5 years post-cut, new-captured-female mass did not recover. Hydroperiod was an important mediator: in the 100m treatment, cutting predominately affected pools that were stressed hydrologically. Overall, salamanders and female frogs were impacted more than male frogs. Our results highlight the importance of individualized metrics like body size, which can reveal sublethal effects and illuminate mechanisms by

Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines.

Science.gov (United States)

Ceballos, Gerardo; Ehrlich, Paul R; Dirzo, Rodolfo

2017-07-25

The population extinction pulse we describe here shows, from a quantitative viewpoint, that Earth's sixth mass extinction is more severe than perceived when looking exclusively at species extinctions. Therefore, humanity needs to address anthropogenic population extirpation and decimation immediately. That conclusion is based on analyses of the numbers and degrees of range contraction (indicative of population shrinkage and/or population extinctions according to the International Union for Conservation of Nature) using a sample of 27,600 vertebrate species, and on a more detailed analysis documenting the population extinctions between 1900 and 2015 in 177 mammal species. We find that the rate of population loss in terrestrial vertebrates is extremely high-even in "species of low concern." In our sample, comprising nearly half of known vertebrate species, 32% (8,851/27,600) are decreasing; that is, they have decreased in population size and range. In the 177 mammals for which we have detailed data, all have lost 30% or more of their geographic ranges and more than 40% of the species have experienced severe population declines (>80% range shrinkage). Our data indicate that beyond global species extinctions Earth is experiencing a huge episode of population declines and extirpations, which will have negative cascading consequences on ecosystem functioning and services vital to sustaining civilization. We describe this as a "biological annihilation" to highlight the current magnitude of Earth's ongoing sixth major extinction event.

Gridded Species Distribution, Version 1: Global Amphibians Presence Grids

Data.gov (United States)

National Aeronautics and Space Administration — The Global Amphibians Presence Grids of the Gridded Species Distribution, Version 1 is a reclassified version of the original grids of amphibian species distribution...

Achieving population-level violence declines: implications of the international crime drop for prevention programming.

Science.gov (United States)

Eisner, Manuel; Nivette, Amy; Murray, Aja Louise; Krisch, Maria

2016-09-01

The Sustainable Development Goals (SDGs) adopted by the United Nations for the period 2016-2030 aim to achieve a substantial reduction of interpersonal violence. An increasing body of evidence of what works, emerging from randomized controlled trials, can inform public health policy decisions. However, there is very limited evidence on the kinds of mechanisms that lead to sustained declines in interpersonal violence at the population level. We discuss the implications of what is known about recent major declines in violence to guide violence-reduction policies.

Predicting the effects of copper on local population decline of 2 marine organisms, cobia fish and whiteleg shrimp, based on avoidance response.

Science.gov (United States)

Araújo, Cristiano V M; Cedeño-Macías, Luís A; Vera-Vera, Victoria C; Salvatierra, David; Rodríguez, Elizabeth N V; Zambrano, Ufredo; Kuri, Samir

2016-02-01

The present study focuses on avoidance response to predict population decline of the marine fish Rachycentron canadum (cobia) and larvae of the estuarine shrimp Litopenaeus vannamei (whiteleg shrimp). Avoidance of approximately 60% was recorded for the cobia fry exposed to 1.0 mg Cu/L, 1.60 mg Cu/L, and 1.80 mg Cu/L. For the shrimp larvae, avoidance was approximately 80% for all Cu concentrations. The population decline of cobia fry was conditioned by avoidance in lower concentrations. However, in higher concentrations mortality begins to play an important role. The displacement toward uncontaminated habitats might determine shrimp population decline. A Cu-contaminated environment can determine the habitat selection of both species and, therefore, their local population decline. © 2015 SETAC.

Factors associated with the catastrophic decline of a cloudforest frog fauna in Guatemala

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J.R Mendelson III

2004-12-01

Full Text Available Comparison of recent and historical surveys of frog populations in cloudforest habitat in Sierra de las Minas,Guatemala,indicated population declines and local extirpation of several species.Pathological exams of diseased tadpoles indicated infection by amphibian chytridiomycosis. The local habitat has been severely altered by recent establishment of large-scale leatherleaf fern production.Analysis of water chemistry at our study site suggested increased nitrogenation associated with the leatherleaf industry.Rev.Biol.Trop.52(4:991-1000. Epub 2005 Jun 24.Una comparación entre un inventario anterior y otro reciente de poblaciones de ranas de bosque nublado en la Sierra de Las Minas de Guatemala demostró disminuciones poblacionales y ausencia localizada de varias especies.El examen patológico de un renacuajo muerto indicó infección por un hongo quítrido propio de los anfibios.El hábitat local ha sido gravemente alterado por el establecimiento reciente de producción a gran escala de helechos ornamentales.El análisis químico del agua en el área de estudio señaló un aumento en nitrogenación asociado al cultivo de helechos.

Evaluación del estado de conservación de los anfibios en Chile Assessment of the conservation status of amphibians in Chile

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HELEN DÍAZ-PÁEZ

2003-09-01

Full Text Available Los anfibios son uno de los grupos con mayores problemas de conservación en la actualidad. La declinación que se produce en numerosas poblaciones a nivel mundial ha llevado a los herpetólogos a reconocer la urgencia de abordar temas relacionados a la biología y estado de conservación de este grupo. En Chile existen numerosas propuestas para categorizar en estados de conservación, tanto a flora como fauna. De allí, que el estado de conservación de la fauna de anfibios haya sido evaluado a nivel nacional y regional. Sin embargo, la revisión de estos trabajos denota el uso reiterado de análisis cualitativos que carecen de datos cuantificables, estando sujetas a observaciones de campo y a la experiencia de los investigadores. Se hace necesario aplicar un método más cuantificable en la categorización de anfibios de manera que sea posible detectar y reconocer los factores que podrían incidir en la disminución de las poblaciones. El presente trabajo recopila la información disponible para los diversos taxa de anfibios chilenos, y evalúa el estado de conservación de la fauna de anfibios que habita en Chile por medio de la adición del índice SUMIN elaborado por Reca et al. (1994 y la propuesta por la Unión Internacional para la Conservación de la Naturaleza (IUCN 2001. Se comparan los resultados de la aplicación de estas metodologías con las evaluaciones previas.At present, amphibians are one of the groups with the most from conservation problems. The decline that is taking place in numerous amphibian populations around the world has led herpetologists to recognize the urgency of studying topics related to the biology and conservation status of this group. In Chile, numerous proposals exist to categorize the conservation status of flora as well as fauna at both national and regional levels. However, most of these works have used qualitative analysis. Because quantifiable data is not available, proposals of conservation status are

Climate change and amphibian diversity patterns in Mexico

DEFF Research Database (Denmark)

Ochoa-Ochoa, Leticia M.; Rodríguez, Pilar; Mora, Franz

2012-01-01

The aim of this article is to characterize at fine scale alpha and beta diversity patterns for Mexican amphibians and analyze how these patterns might change under a moderate climate-change scenario, highlighting the overall consequences for amphibian diversity at the country level. We used a geo...

Influence of demography and environment on persistence in toad populations

Science.gov (United States)

Lambert, Brad A.; Schorr, Robert A.; Schneider, Scott C.; Muths, Erin L.

2016-01-01

Effective conservation of rare species requires an understanding of how potential threats affect population dynamics. Unfortunately, information about population demographics prior to threats (i.e., baseline data) is lacking for many species. Perturbations, caused by climate change, disease, or other stressors can lead to population declines and heightened conservation concerns. Boreal toads (Anaxyrus boreas boreas) have undergone rangewide declines due mostly to the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), with only a few sizable populations remaining in the southern Rocky Mountains, USA, that are disease-free. Despite the apparent region-wide occurrence of Bd, our focal populations in central Colorado were disease free over a 14-year capture-mark-recapture study until the recent discovery of Bd at one of the sites. We used recapture data and the Pradel reverse-time model to assess the influence of environmental and site-specific conditions on survival and recruitment. We then forecast changes in the toad populations with 2 growth models; one using an average lambda value to initiate the projection, and one using the most recent value to capture potential effects of the incursion of disease into the system. Adult survival was consistently high at the 3 sites, whereas recruitment was more variable and markedly low at 1 site. We found that active season moisture, active season length, and breeding shallows were important factors in estimating recruitment. Population growth models indicated a slight increase at 1 site but decreasing trends at the 2 other sites, possibly influenced by low recruitment. Insight into declining species management can be gained from information on survival and recruitment and how site-specific environmental factors influence these demographic parameters. Our data are particularly useful because they provide baseline data on demographics in populations before a disease outbreak and enhance our ability to detect changes