Quantitative evidence for the effects of multiple drivers on continental-scale amphibian declines
Authors: Grant EHC, Miller DAW, Schmidt BR, Adams MJ, Amburgey SM, Chambert TC, Cruickshank SS, Fisher RN, Green DM, Hossack BR, Johnson PTJ, Joseph MB, Rittenhouse T, Ryan M, Waddle JH, Walls SC, Bailey LL, Fellers GM, Gorman TA, Ray AM, Pilliod DS, Price SJ, Saenz D, Muths E | Outlet: Scientific Reports xx:xxx-xxx
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.
Estimating abundance in the presence of species uncertainty
Authors: Chambert T, Hossack BR, Fishback L, Davenport JM | Outlet: Methods in Ecology and Evolution
Uncertainty in biological monitoring: a framework fordata collection and analysis to account for multiplesources of sampling bias
Authors: Ruiz-Gutierrez V, Hooten MB, Grant EHC | Outlet: Methods in Ecology and Evolution doi/10.1111/2041-210X.12542
eSummary(1) Biological monitoring programs are increasingly relying upon large volumes of citizenscience data to improve the scope and spatial coverage of information, ch a l l en g i n g thescienti&#64257;c commun i ty to develop design and model - b ase d approaches to improve inference.(2) Recent statistical models in ecology have be en develope d to accommodate false-negativeerrors, although recent work points to false positive errors as equally important sources ofbias. This is of particular concern for the success of any m o n i t or i n g program given rates assmall as 3% could lead to th e overestimation of the occurrence of rare events by as much as50%, and even small false positive r a t es can severely b i as estimates of occurrence dynamics.(3) We present an int eg ra t ed , comput at i o n al l y e&#64259;cient Bayesian hierar chical model tocorrect for fal se positi ve and negative error s in detection/no n -d et ec ti o n data. Our modelcombines ind ependent, a u x i l i ar y data sources with &#64257;eld observations to i m p r ove t h eestimation of false positive rate s, when a subset of &#64257;eld observatio n s cannot be validated aposteriori or assumed as per fe ct . We evaluated the performance of the model across arange of occurren ce rates, false positive and negative errors, and quantity of auxil i ar y data.(4) Th e mode l perfor m ed well under all simulated scenario s, and we were able t o identifycritical auxiliary data characteristics which resul t ed in improved infer en ce. We applied ourfalse positive m odel to a large-scale, citizen -sci e n ce monitor i n g program for anurans in theNortheastern U.S., using auxiliary data from an experiment d esi g n ed to estimate falsepositive er r o r rates. Not correcting for false positive ra t es resulted in biased estimates ofoccupancy in 4 of the 10 anu r a n species we an a l y zed , leadin g to an overestima t i on of theaverage number of occupi ed survey routes by as much as 70%.Conclusions. The framework we present for da ta collecti o n and analysis is able toe&#64259;ciently pr ovide reliable inference for occurrence patterns using data from acitizen-science monitorin g program . However, our approach is ap p l i ca b le to data generatedby any type of research and monit or i n g program , independent of skill level or scale, when e&#64256;ort i s placed on obtaining independent info rma t i on on false positive rates
Spatial variation in risk and consequence of Batrachochytrium salamanderivorans introduction in the United States
Authors: Richgels K, Russell R, Adams M, Grant E | Date: 2016-02-17 | Outlet: Royal Society Open Science 3:150616 | Format: .PDF
A newly identified fungal pathogen, <i>Batrachochytrium salamandrivorans</i> (<i>Bsal</i>), is responsible for mass mortality events and severe population declines in European salamanders. The eastern USA has the highest diversity of salamanders in the world and the introduction of this pathogen is likely to be devastating. Although data is inevitably limited for new pathogens, disease risk assessments utilize best available data to inform management decisions. Using characteristics of <i>Bsal</i> ecology, spatial data on imports and pet trade establishments, and salamander species diversity, we identify high risk areas with both a high likelihood of introduction and severe consequences for local salamanders. We predict that the Pacific coast, southern Appalachian Mountains, and mid-Atlantic regions will have the highest relative risk from <i>Bsal</i>. Management of invasive pathogens becomes difficult once they are established in wildlife populations; therefore, import restrictions to limit pathogen introduction and early detection through surveillance of high risk areas are priorities for preventing the next crisis for North American salamanders
Integrating biology, field logistics, and simulations to optimize parameter estimation for imperiled species
Authors: Lanier WE, Bailey LL, Muths E | Date: 2016 | Outlet: Ecological Modeling | Format: .PDF
Conservation of imperiled species often requires knowledge of vital rates and population dynamics. However, these can be difficult to estimate for rare species and small populations. This problem is further exacerbated when individuals are not available for detection during some surveys due to limited access, delaying surveys and creating mismatches between the breeding behavior and survey timing. Here we use simulations to explore the impacts of this issue using four separate boreal toad (Anaxyrus boreas boreas) populations, representing combinations of logistical access (accessible, inaccessible) and breeding behavior (synchronous, asynchronous). We examine the bias and precision of survival and breeding probability estimates generated by survey designs that differ in effort and timing for these populations.
A Model to Inform Management Actions as a Response to Chytridiomycosis-Associated Decline
Authors: Converse SJ, Bailey LL, Mosher BA, Funk WC, Gerber BD, Muths E | Date: 2016-02-15 | Outlet: Ecohealth | Format: .PDF
Decision-analytic models provide forecasts of how systems of interest will respond to management. These models can be parameterized using empirical data, but sometimes require information elicited from experts. When evaluating the effects of disease in species translocation programs, expert judgment is likely to play a role because complete empirical information will rarely be available. We illustrate development of a decision-analytic model built to inform decision-making regarding translocations and other management actions for the boreal toad (Anaxyrus boreas boreas), a species with declines linked to chytridiomycosis caused by Batrachochytrium dendrobatidis (Bd).
Non-native and native organisms moving into high elevation and high latitude ecosystems in an era of climate change: new challenges for ecology and conservation
Authors: Albihn A, Alexander J, Burgess T, Daehler C, Englund G, Essl F, Evengård B, Greenwood G, Haider S, Lenoir J, McDougall K, Muths E, Nuñez M, Olofsson J, Pellissier L, Rabitsch W, Rew L, Robertson M, Sanders N, Kueffer C, Milbau A, Pauchard A | Date: 2016 | Outlet: Biological Invasions | Format: .PDF
Cold environments at high elevation and high latitude are often viewed as resistant to biological invasions. However, climate warming, land use change and associated increased connectivity all increase the risk of biological invasions in these environments. Here we present a summary of the key discussions of the workshop ‘Biosecurity in Mountains and Northern Ecosystems: Current Status and Future Challenges’ (Flen, Sweden, 1-3 June 2015). The aims of the workshop were to (i) increase awareness about the growing importance of species expansion – both non-native and native – at high elevation and high latitude with climate change, (ii) review existing knowledge about invasion risks in these areas, and (iii) encourage more research on how species will move and interact in cold environments, and the consequences for animal and human health and wellbeing. The diversity of potential and actual invaders reported at the workshop and the likely interactions between them create major challenges for managers of cold environments. However, since these cold environments have experienced fewer invasions when compared with many warmer, more populated environments, prevention has a real chance of success, especially if it is coupled with prioritisation schemes for targeting invaders likely to have greatest impact. Communication and co-operation between cold environment regions will facilitate rapid response and maximise use of limited research and management resources.
Amphibian mortality events and ranavirus outbreaks in the Greater Yellowstone Ecosystem
Authors: Patla D, St-Hilaire S, Ray A, Hossack B R, Peteron C R | Date: 2016 | Outlet: Herptetological Review 47:50-54 | Format: .PDF
Mortality events in wild amphibians go largely undocumented, and where events are detected, the numbers of dead amphibians observed are probably a small fraction of actual mortality. Incidental observations from field surveys can, despite limitations, provide valuable information on the presence, host species, and spatial distribution of diseases. Here we summarize amphibian mortality events and diagnoses recorded from 2000 to 2014 in four management areas: Yellowstone National Park; Grand Teton National Park; the John D. Rockefeller, Jr. Memorial Parkway; and the National Elk Refuge, which together span a large portion of protected areas within the Greater Yellowstone Ecosystem.
Restored agricultural wetlands in central Iowa: habitat quality and amphibian response
Authors: Reeves RA, Pierce CL, Smalling KL, Klaver RW, Vandever MW, Battaglin WA, Muths E | Date: 2016-02 | Outlet: Wetlands | Format: .PDF
Amphibians are declining throughout the United States and worldwide due, partly, to habitat loss. The Iowa Conservation Reserve Enhancement Program (CREP) strategically restores wetlands to denitrify tile drainage effluent and restore ecosystem services. Understanding how eutrophication , 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 CREP 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 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 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.
An alternative framework for responding to the amphibian crisis
Authors: Muths E, Fisher RN | Outlet: Oryx | Format: .PDF
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 lack of cohesion and inertia in responding to amphibian issues. While we acknowledge existing efforts and the prodigious amount of useful research, we suggest that a change is warranted and that the identification of a new amphibian chytrid provides the impetus for such a change.