Recent Products

ARMI biologists are always engaging in different amphibian studies across the country. Here is a list of their most recently published products.

Papers & Reports From eDNA to decisions using a multi-method approach to restoration planning in streams
Authors: Andrea J Adams; Colleen Kamoroff; Rob L Grasso; Brian J Halstead; Patrick M Kleeman; Katherine Powelson; Travis Seaborn; Claudia Mengelt; Caren S Goldberg; Ninette R Daniele
Date: 2024-06-21 | Outlet: Scientific Reports
Reintroduction efforts are increasingly used to mitigate biodiversity losses, but are frequently challenged by inadequate planning and uncertainty. High quality information about population status and threats can be used to prioritize reintroduction and restoration efforts and can transform ad hoc approaches into opportunities for improving conservation outcomes at a landscape scale. We conducted comprehensive environmental DNA (eDNA) and visual encounter surveys to determine the distribution of native and non?native aquatic species in two high?priority watersheds to address key uncertainties—such as the distribution of threats and the status of existing populations—inherent in restoration planning. We then used these occurrence data to develop a menu of potential conservation actions and a decision framework to benefit an endangered vertebrate (foothill yellow?legged frog, Rana boylii) in dynamic stream systems. Our framework combines the strengths of multiple methods, allowing managers and conservation scientists to incorporate conservation science and site?specific knowledge into the planning process to increase the likelihood of achieving conservation goals.
Papers & Reports Effects of harmful algal blooms on amphibians and reptiles are underreported and underrepresented
Authors: Brian J Tornabene; Kelly L Smalling; Blake R Hossack
Date: 2024-07-05 | Outlet: Environmental Toxicology & Chemistry
Harmful algal blooms (HABs) are a persistent and increasing problem globally, yet we still have a limited knowledge about how they affect many wildlife. Although semi-aquatic and aquatic amphibians and reptiles have experienced large declines and occupy environments where HABs are increasingly problematic, their vulnerability to HABs remains unclear. To inform monitoring, management, and future studies, we conducted a literature review and synthesized studies and reported mortality events describing effects of cyanotoxins from HABs on freshwater herpetofauna. Our review identified 37 unique studies and 71 endpoints (no-observed-effect and lowest-observed-effect concentrations) involving 11 amphibian and three reptile species worldwide. Responses varied widely among studies, species, and concentrations used in experiments. Concentrations causing lethal and sublethal effects in experiments were generally 1–100 µg/L, which is near the mean value of reported events but 70times less than the maximum cyanotoxin concentrations reported in the environment. However, one species of amphibian was tolerant to concentrations of 10,000 µg/L, demonstrating potentially immense differences in sensitivities. Most studies focused on microcystin-LR (MC-LR), which can increase systemic inflammation and harm the digestive system, reproductive organs, liver and kidneys, and development. The few studies on other cyanotoxins illustrated that effects resembled those of MC-LR at similar concentrations, but more research is needed to describe effects. All experimental studies were on larval and adult amphibians; there were no such studies on reptiles. Experimental work with reptiles and adult amphibians is needed to clarify thresholds of tolerance. Only nine mortality events were reported, mostly for reptiles. Given that amphibians likely decay faster than reptiles, which have tissues that resists decomposition, mass amphibian mortality events from HABs have likely been underreported. We propose seven major areas to focus future efforts to enhance our understanding of effects and monitoring of HABs on herpetofauna that fill important roles in freshwater and terrestrial environments.
Papers & Reports Decision analysis and adaptive management: strategies to overcome challenges of uncertainty and inaction.
Authors: Katherine M O'Donnell; Evan HC Grant
Outlet: Society for the Study of Amphibians and Reptiles Herpetological Conservation Series
A book chapter highlighting uncertainty and inaction in conservation, decision analysis steps and challenges and decision analysis for amphibians and reptiles
Papers & Reports Of toads and tolerance: Quantifying intraspecific variation in host resistance and tolerance to a lethal pathogen
Authors: Bennett Hardy; Erin Muths; W C Funk; Larissa L Bailey
Date: 2024-05-30 | Outlet: Journal of Animal Ecology
Due to the ubiquity of disease in natural systems, hosts have evolved strategies of disease resistance and tolerance to defend themselves from further harm once infected. Resistance strategies directly limit pathogen growth, typically leading to lower infection burdens in the host. A tolerance approach limits the fitness consequences caused by the pathogen but does not directly inhibit pathogen growth. Testing for intraspecific variation in wild host populations is important for informing conservation decisions about captive breeding, translocation, and disease treatment. Here, we test for the relative importance of tolerance and resistance in multiple populations of boreal toads (Anaxyrus boreas boreas) against Batrachochytrium dendrobatidis (Bd), the amphibian fungal pathogen responsible for the greatest host biodiversity loss due to disease. Boreal toads have severely declined in Colorado (CO) due to Bd, but toad populations challenged with Bd in western Wyoming (WY) appear to be less affected. We used a common garden infection experiment to expose post-metamorphic toads sourced from four populations (2 in CO and 2 in WY) to Bd and monitored changes in mass, pathogen burden, and survival for eight weeks. We used a multi-state modeling approach to estimate weekly survival and transition probabilities between infected and cleared states, reflecting a dynamic infection process that traditional approaches fail to capture. We found that WY boreal toads are highly tolerant to Bd infection with higher survival probabilities than those in CO when infected with identical pathogen burdens. WY toads also had higher probabilities of clearing infections and took an average of five days longer to reach peak infection burdens. Our results demonstrate strong intraspecific differences in tolerance and resistance that explain why population declines vary regionally across the species. We used a robust, multi-state framework to gain inference on typically hidden disease processes when testing for host tolerance or resistance and demonstrated that describing an entire species as ‘tolerant’ or ‘resistant’ is unwise without testing for intraspecific variation in host defenses.
Papers & Reports Matching decision support modeling frameworks to disease emergence stages
Authors: Evan HC Grant; Brittany A Mosher; Riley F Bernard; Alexander D Wright; Robin E Russell
Wildlife disease management decisions often require rapid responses to situations that are fraught with uncertainty. By recognizing that management is implemented to achieve specific objectives (whether defined explicitly or not), resource managers and science partners can identify an analysis technique and develop a plan to collect necessary data that will allow for the evaluation of management actions.
Papers & Reports Preparing for a Bsal invasion into North America has improved multi-sector readiness
Authors: Deanna H Olson; Evan HC Grant; Molly Bletz; Jonah Piovia-Scott; Jacob L Kerby; Michael J Adams; Florencia M Breitman; Michelle R Christman; María J Forzán; Matthew J Gray; Aubree J Hill; M S Koo; David Lesbarrères; Olga Milenkaya; Eria A Rebollar; Louise A Rollins-Smith; Megan Serr; Alex Shepak; Lenny Shirose; L Sprague; Jenifer Walke; Alexa R Warwick; Brittany A Mosher
Western palearctic salamander susceptibility to the skin disease caused by the amphibian chytrid fungus Batrachochytrium salamandrivorans (Bsal) was recognized in 2014, eliciting concerns for a potential novel wave of amphibian declines following the B. dendrobatidis (Bd) chytridiomycosis global pandemic. Although Bsal had not been detected in North America, initial experimental trials supported the heightened susceptibility of caudate amphibians to Bsal chytridiomycosis.
Papers & Reports Contrasting demographic responses under future climate at multiple life stages for two populations of a montane amphibian
Authors: Amanda M Kissel; Wendy J Palen; Michael J Adams; Justin Garwood
Date: 2024-01-03 | Outlet: Climate Change Ecology
For species with complex life histories, climate change can have contrasting effects for different life stages within locally adapted populations and may result in responses counter to general climate change predictions. Using data from two, 14-year demographic studies for a North American montane amphibian, Cascades frog (Rana cascadae), we quantified how aspects of current climate influenced annual survival of larvae and adult stages and modeled the stochastic population growth rate (?s) of each population for current (1980-2006) and future periods (2080s). Climate drivers of survival for the populations were similar for larvae (i.e. decreases in precipitation lead to pond drying and mortality), but diverged for terrestrial stages where decreases in winter length and summer precipitation had opposite effects. By the 2080s, we predict one population will be in sharp decline (?s = 0.90),while the other population will remain nearly stable (?s = 0.99) in the absence of other stressors, such as mortality due to disease. Our case study demonstrates a result counter to many climate envelope predictions in that stage-specific responses to local climate and hydrology result in a higher extinction risk for the more northern population.
Papers & Reports Terrestrial Movement Patterns of the Common Toad (Bufo bufo) in Central Spain Reveal Habitat of Conservation Importance
Authors: David R Daversa; Erin Muths; Jaime Bosch
Date: 2012 | Outlet: Journal of Herpetology, 46(4):658-664
Journal of Herpetology, 46(4):658-664
Papers & Reports Native amphibian toxin reduces invasive crayfish feeding with potential benefits to stream biodiversity
Authors: Gary Bucciarelli; Sierra J. Smith; Justin J. Choe; Phoebe D. Shin; Robert N Fisher; Lee B Kats
Date: 2023-09-13 | Outlet: BMC Ecology and Evolution 23, 51
Biodiversity is generally reduced when non-native species invade an ecosystem. Invasive crayfish, Procambarus clarkii, populate California freshwater streams, and in the Santa Monica Mountains (Los Angeles, USA), their introduction has led to trophic cascades due to omnivorous feeding behavior and a rapid rate of population growth. The native California newt, Taricha torosa, possesses a neurotoxin, tetrodotoxin (TTX), that affects freshwater animal behavior. Given P. clarkii has a limited evolutionary history with TTX, we hypothesized that TTX may affect crayfish feeding behaviors. To determine if TTX affects P. clarkii behavior, we measured cumulative movement and various feeding behaviors of P. clarkii exposed to (i) waterborne, ecologically realistic concentrations of TTX (~?3.0?×?10??8 moles/L), (ii) an anuran chemical cue to account for intraguild cues, or (iii) a T. torosa chemical cue with quantitated TTX in it (~?6.2?×?10??8 moles/L).

We found that the presence of TTX in any form significantly reduced crayfish movement and decreased the amount of food consumed over time. Crayfish responses to the anuran treatment did not significantly differ from controls.

Our laboratory results show that naturally occurring neurotoxin from native California newts limits invasive crayfish foraging and feeding rates, which may play a role in preserving local stream ecosystems by limiting invasive crayfish behaviors that are detrimental to biodiversity.
Papers & Reports BioLake: A first assessment of lake temperature-derived bioclimatic predictors for aquatic invasive species
Authors: Ryan C Burner; Wesley M. Daniel; Peder S. Engelstad; Christopher J. Churchill; Richard E Erickson
Date: 2023-07-10 | Outlet: Ecosphere 14(7):e4616
Aquatic invasive species (AIS) present major ecological and economic challenges globally, endangering ecosystems and human livelihoods. Managers and policy makers thus need tools to predict invasion risk and prioritize species and areas of concern, and they often use native range climate matching to determine whether a species could persist in a new location. However, climate matching for AIS often relies on air temperature rather than water temperature due to a lack of global water temperature data layers, and predictive power of models is seldom evaluated. We developed 12 global lake (water) temperature-derived “BioLake” bioclimatic layers for distribution modeling of aquatic species and compared “climatch” climate matching predictions (from climatchR package) from BioLake with those based on BioClim temperature layers and with a null model. We did this for 73 established AIS in the United States, training the models on their ranges outside of the United States and Canada. Models using either set of climate layers outperformed the null expectation by a similar (but modest) amount on average, but some species were occasionally found in locations with low climatch scores. Mean US climatch scores were higher for most species when using air temperature. Including additional climate layers in models reduced mean climatch scores, indicating that commonly used climatch score thresholds are not absolute but can be context specific and may require calibration based upon climate data used. Although finer resolution global lake temperature data would likely improve predictions, our BioLake layers provide a starting point for aquatic species distribution modeling. Climate matching was most effective for some species that originated at low latitudes or had small ranges. Climatch scores remain useful but limited for predicting AIS risk, perhaps because current ranges seldom fully reflect climatic tolerances (fundamental niches). Managers could consider climate matching as one of a suite of tools that can be used in AIS prioritization.

* USGS neither sponsors nor endorses non-USGS web sites; per requirement "3.4.1 Prohibition of Commercial Endorsement."
* PDF documents require Adobe Reader or Google Chrome Browser for viewing.