Landscape epidemiology of <i>Batrachochytrium dendrobatidis</i> in central California

Padgett-Flohr, Gretchen E.; Hopkins, Robert L.

doi:10.1111/j.1600-0587.2009.05994.x

Cited by 22 publications

(14 citation statements)

References 55 publications

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“…Our observations of relatively high Bd loads and lesions consistent with severe chytridiomycosis coinciding with a mass mortality event make this the first published report of lethal chytridiomycosis in R. boylii in the field. Although Bd has been detected many miles upstream of the current study site in a tributary of Arroyo Hondo over the last decade (Padgett‐Flohr and Hopkins ), these were the first indications of negative effects of Bd infection among lotic‐breeding frogs in the watershed. Bd has been documented in the watershed from museum specimens collected in 1966, and in live animals as recently as 2007 (Padgett‐Flohr and Hopkins , ), approximately 5 miles upstream of the closest sampling location used in this study, but it is possible that the 2013 outbreak may have been the result of an introduction of a novel genotype of Bd to the watershed.…”

Section: Discussionmentioning

confidence: 82%

Extreme drought, host density, sex, and bullfrogs influence fungal pathogen infection in a declining lotic amphibian

et al. 2017

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Briggs. 2017. Extreme drought, host density, sex, and bullfrogs influence fungal pathogen infection in a declining lotic amphibian. Ecosphere 8(3):e01740. 10. 1002/ecs2.1740 Abstract. Freshwater biodiversity is imperiled across the globe, and multiple stressors such as habitat alteration, non-native species invasion, disease, and climate change can act in concert to threaten vulnerable taxa. The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis, is one of the causative factors of severe amphibian declines. The foothill yellow-legged frog (Rana boylii) is a stream-breeding anuran endemic to California and Oregon (USA) that has declined precipitously in recent decades, yet there is little information on its susceptibility to Bd. In the fall of 2013, we observed dead and dying juvenile R. boylii in a San Francisco Bay Area watershed where annual amphibian breeding censuses have been conducted since 1997 in a free-flowing reach and since 2003 in an anthropogenically modified stream reach. High pathogen loads on R. boylii and histologic lesions observed on a dead R. boylii metamorph collected from the site were consistent with lethal chytridiomycosis. The outbreak coincided with extremely low stream flows in autumn that concentrated frogs in drying pools and the absence of high peak flows in winter that allowed non-native American bullfrogs (Rana catesbeiana) to expand their spatial distribution in the stream network. Following the outbreak, we surveyed R. boylii and sympatric anurans at the site for the next two years to determine Bd trends within the population. Using mixed-effects models, we found that bullfrog presence was a positive predictor of both Bd prevalence and Bd load in R. boylii. Prevalence was also influenced by sex and life stage: Adult males were more likely to be infected than either females or juveniles. Moreover, we found that stream flow volume was negatively associated with Bd load. These results indicate that disease, drought, and flow regulation may interact synergistically to impact amphibians in ways not previously recognized, informing stream flow management strategies for native aquatic taxa.

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Section: Discussionmentioning

confidence: 82%

Extreme drought, host density, sex, and bullfrogs influence fungal pathogen infection in a declining lotic amphibian

et al. 2017

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“…Bd has now been documented in at least 14 species of amphibians in California, nearly all the species that have been examined carefully. However, the prevalence of Bd in wild populations in California is largely unknown except for R. muscosa (Southern Mountain Yellow-legged Frog), R. sierrae (formerly part of R. muscosa; Vredenburg et al 2007) in the Sierra Nevada (Briggs et al 2005;Vredenburg et al 2010), and in all six species of local amphibians in a set of ponds in Santa Clara County (Padgett-Flohr and Hopkins 2010).…”

Section: Introductionmentioning

confidence: 99%

Comparing the Status of Two Sympatric Amphibians in the Sierra Nevada, California: Insights on Ecological Risk and Monitoring Common Species

Brown¹,

Wilkinson²,

Kiehl³

2014

Journal of Herpetology

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Abstract.-We found amphibian chytrid fungus (Bd = Batrachochytrium dendrobatidis) to be widespread within a coastal watershed at Point Reyes National Seashore, California and within two high elevation watersheds at Yosemite National Park, California. Bd was associated with all six species that we sampled (Bufo boreas, B. canorus, Pseudacris regilla, Rana draytonii, R. sierrae, and Lithobates catesbeianus). For those species sampled at 10 or more sites within a watershed, the percentage of Bd-positive sites varied from a low of 20.7% for P. regilla at one Yosemite watershed to a high of 79.6% for P. regilla at the Olema watershed at Point Reyes. At Olema, the percent of Bd-positive water bodies declined each year of our study (2005)(2006)(2007). Because P. regilla was the only species found in all watersheds, we used that species to evaluate habitat variables related to the sites where P. regilla was Bd-positive. At Olema, significant variables were year, length of shoreline (perimeter), percentage cover of rooted vegetation, and water depth. At the two Yosemite watersheds, water depth, water temperature, and silt/mud were the most important covariates, though the importance of these three factors differed between the two watersheds. The presence of Bd in species that are not declining suggests that some of the amphibians in our study were innately resistant to Bd, or had developed resistance after Bd became established.

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“…, 2005). Padgett‐Flohr & Hopkins (2009, 2010) suggest that P. regilla may be a resistant carrier of Bd, effectively vectoring it to ephemeral habitats where it may infect more susceptible species.…”

Section: Introductionmentioning

confidence: 99%

The effects of multiple stressors on wetland communities: pesticides, pathogens and competing amphibians

et al. 2011

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1. Anthropogenic effects have propelled us into what many have described as the sixth mass extinction, and amphibians are among the most affected groups. The causes of global amphibian population declines and extinctions are varied, complex and context-dependent and may involve multiple stressors. However, experimental studies examining multiple factors contributing to amphibian population declines are rare. 2. Using outdoor mesocosms containing zooplankton, phytoplankton, periphyton and tadpoles, we conducted a 2 · 2 · 3 factorial experiment that examined the separate and combined effects of an insecticide and the fungal pathogen Batrachochytrium dendrobatidis (Bd) on three different assemblages of larval pacific treefrogs (Pseudacris regilla) and Cascades frogs (Rana cascadae). 3. Larval amphibian growth and development were affected by carbaryl and the amphibian assemblage treatment, but only minimally by Bd. Carbaryl delayed metamorphosis in both amphibian species and increased the growth rate of P. regilla. Carbaryl also reduced cladoceran abundance, which, in turn, had positive effects on phytoplankton abundance but no effect on periphyton biomass. Substituting 20 intraspecific competitors with 20 interspecific competitors decreased the larval period but not the growth rate of P. regilla. In contrast, substituting 20 intraspecific competitors with 20 interspecific competitors had no effect on R. cascadae. Results of real-time quantitative polymerase chain reaction (qPCR) analysis confirmed infection of Bd-exposed animals, but exposure to Bd had no effects on either species in univariate analyses, although it had significant or nearly significant effects in several multivariate analyses. In short, we found no interactive effects among the treatments on amphibian growth and development. 4. We encourage future research on the interactive effects of pesticides and pathogens on amphibian communities.

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Landscape epidemiology of Batrachochytrium dendrobatidis in central California

Cited by 22 publications

References 55 publications

Extreme drought, host density, sex, and bullfrogs influence fungal pathogen infection in a declining lotic amphibian

Extreme drought, host density, sex, and bullfrogs influence fungal pathogen infection in a declining lotic amphibian

Comparing the Status of Two Sympatric Amphibians in the Sierra Nevada, California: Insights on Ecological Risk and Monitoring Common Species

The effects of multiple stressors on wetland communities: pesticides, pathogens and competing amphibians

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