The U.S. Geological Survey Amphibian Research Monitoring Initiative (ARMI) is using a combination of swabbing, non-lethal tissue sampling, soil and water sampling, and collection of a variety of other environmental variables to determine the relationships between the prevalence and pathogen load of Bd infection and environmental stressors on green treefrog survival.
The Science Issue and Relevance: Batrachochytrium dendrobatidis (Bd) is a species of chytrid fungus and the causative agent of the infectious disease chytridiomycosis. In the last three decades, Bd has caused the catastrophic decline or extinction of more than 200 species of frogs. The fungus is prevalent in aquatic habitats in which many frogs breed, spreading via flagellated aquatic zoospores. The primary clinical sign of infection is thickening of the outermost layer of skin leading to a reduced capacity for osmotic regulation. The resulting ion disruption often leads to cardiac arrest and death. It is hypothesized that environmental stressors such as salinity, water temperature, pH, and bioavailable mercury (extent to which mercury is absorbed by the body) levels can exacerbate the effects of Bd. We are investigating how frog survival rates are impacted by the interaction of environmental stressors and Bd.
Methodology for Addressing the Issue: The U.S. Geological Survey Amphibian Research Monitoring Initiative (ARMI) began a nationwide study implementing capture-mark-recapture techniques in 2018. The study uses a combination of swabbing, non-lethal tissue sampling, soil and water sampling, and collection of a variety of other environmental variables to determine the relationships between the prevalence and pathogen load of Bd infection and environmental stressors. For three nights in a two-week span twice a year, we capture green frogs (Lithobates clamitans) at a small pond in Sherburne Wildlife Management Area in South-Central Louisiana. We note sex in adults, measure snout-vent length, swab the skin for the presence of Bd, and take toe clips for mercury analysis from all captured individuals. Lastly, we uniquely mark each individual by inserting a passive integrated transponder (PIT) tag into the body before release back into the pond. Recapturing PIT-tagged individuals allows us to estimate survival as a function of pathogen load and examine the effect of environmental stressors across time.
Future Steps: We will continue the current sampling protocol twice a year. Beginning in spring 2020, we will collect dragonfly and damselfly larvae at the study site to better understand the relationships among mercury levels in the environment, food items, and amphibians.
Below are other science projects associated with this project.
Below are publications associated with this project.
Prevalence of Batrachochytrium dendrobatidis and B. salamandrivorans in the Gulf Coast Waterdog, Necturus beyeri, from Southeast Louisiana, USA
Quantitative evidence for the effects of multiple drivers on continental-scale amphibian declines
- Overview
The U.S. Geological Survey Amphibian Research Monitoring Initiative (ARMI) is using a combination of swabbing, non-lethal tissue sampling, soil and water sampling, and collection of a variety of other environmental variables to determine the relationships between the prevalence and pathogen load of Bd infection and environmental stressors on green treefrog survival.
The Science Issue and Relevance: Batrachochytrium dendrobatidis (Bd) is a species of chytrid fungus and the causative agent of the infectious disease chytridiomycosis. In the last three decades, Bd has caused the catastrophic decline or extinction of more than 200 species of frogs. The fungus is prevalent in aquatic habitats in which many frogs breed, spreading via flagellated aquatic zoospores. The primary clinical sign of infection is thickening of the outermost layer of skin leading to a reduced capacity for osmotic regulation. The resulting ion disruption often leads to cardiac arrest and death. It is hypothesized that environmental stressors such as salinity, water temperature, pH, and bioavailable mercury (extent to which mercury is absorbed by the body) levels can exacerbate the effects of Bd. We are investigating how frog survival rates are impacted by the interaction of environmental stressors and Bd.
Green frog (Photo by Brad Glorioso) Methodology for Addressing the Issue: The U.S. Geological Survey Amphibian Research Monitoring Initiative (ARMI) began a nationwide study implementing capture-mark-recapture techniques in 2018. The study uses a combination of swabbing, non-lethal tissue sampling, soil and water sampling, and collection of a variety of other environmental variables to determine the relationships between the prevalence and pathogen load of Bd infection and environmental stressors. For three nights in a two-week span twice a year, we capture green frogs (Lithobates clamitans) at a small pond in Sherburne Wildlife Management Area in South-Central Louisiana. We note sex in adults, measure snout-vent length, swab the skin for the presence of Bd, and take toe clips for mercury analysis from all captured individuals. Lastly, we uniquely mark each individual by inserting a passive integrated transponder (PIT) tag into the body before release back into the pond. Recapturing PIT-tagged individuals allows us to estimate survival as a function of pathogen load and examine the effect of environmental stressors across time.
The study pond in Sherburne Wildlife Management Area in the Atchafalaya Basin, Louisiana (Photo by Brad M. Glorioso) Future Steps: We will continue the current sampling protocol twice a year. Beginning in spring 2020, we will collect dragonfly and damselfly larvae at the study site to better understand the relationships among mercury levels in the environment, food items, and amphibians.
- Science
Below are other science projects associated with this project.
- Publications
Below are publications associated with this project.
Prevalence of Batrachochytrium dendrobatidis and B. salamandrivorans in the Gulf Coast Waterdog, Necturus beyeri, from Southeast Louisiana, USA
The globally widespread amphibian fungal pathogen Batrachochytrium dendrobatidis (Bd) has been linked to amphibian declines worldwide (Lips et al. 2006; Skerratt et al. 2007). In Louisiana, USA, Bd has been found in several amphibian species (Chatfield et al. 2012; Rothermel et al. 2008), but to our knowledge no population-level die-offs have been observed. Published literature on Bd prevalence inAuthorsBrad M. Glorioso, J. Hardin Waddle, Corinne L. Richards-ZawackiQuantitative evidence for the effects of multiple drivers on continental-scale amphibian declines
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 extinAuthorsEvan H. Campbell Grant, David A. W. Miller, Benedikt R. Schmidt, M. J. Adams, Staci M. Amburgey, Thierry A. 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 L. Muths