Risk Factors and Declines in Northern Cricket Frogs (Acris crepitans)

Beasley, Val R.; Faeh, Sandra A.; Wikoff, Brigit; Staehle, Craig; Eisold, Joyce; Nichols, Donald K.; Cole, Rebecca A.; Schotthoefer, Anna M.; Greenwell, M.; Brown, Lauren E.

doi:10.1525/california/9780520235922.003.0013

Cited by 25 publications

(18 citation statements)

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“…Quality of wetland-specific measurements and ease of interpretability of the numerous landscape metrics obtained from the FRAGSTATS analysis were also considered in retaining variables for further evaluation. In addition, we chose to retain wetland variables that were expected to be important based on basic knowledge of parasite life cycles and predictions made in the amphibian health literature (e.g., that anthropogenic chemicals and nutrients should influence parasitism, e.g., Kiesecker 2002, Beasley et al 2005, Johnson et al 2007). We also retained specific landscape variables to explore not only the potential influence of landscape composition (percent cover of land use types, LD), but also the influence of landscape structure, measured as patch density (PD), largest patch index (LPI), mean patch size (MPS), and mean nearest neighbor patch distances (MNN) for particular land use types; specifically, AG, FOR, WW, PEW, and OW.…”

Section: Data Analysesmentioning

confidence: 99%

Effects of wetland vs. landscape variables on parasite communities ofRana pipiens: links to anthropogenic factors

Schotthoefer

Rohr

Cole

et al. 2011

Ecological Applications

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The emergence of several diseases affecting amphibian populations worldwide has prompted investigations into determinants of the occurrence and abundance of parasites in frogs. To understand the spatial scales and identify specific environmental factors that determine risks of parasitism in frogs, helminth communities in metamorphic frogs of the northern leopard frog (Rana pipiens) were examined in relation to wetland and landscape factors at local (1 km) and regional (10 km) spatial extents in an agricultural region of Minnesota (USA) using regression analyses, ordination, and variance partitioning techniques. Greater amounts of forested and woody wetland habitats, shorter distances between woody wetlands, and smaller-sized open water patches in surrounding landscapes were the most consistently positive correlates with the abundances, richness, and diversity of helminths found in the frogs. Wetland and local landscape variables were suggested as most important for larval trematode abundances, whereas local and regional landscape variables appeared most important for adult helminths. As previously reported, the sum concentration of atrazine and its metabolite desethylatrazine, was the strongest predictor of larval trematode communities. In this report, we highlight the additional influences of landscape factors. In particular, our data suggest that anthropogenic activities that have resulted in the loss of the availability and connectivity of suitable habitats in the surrounding landscapes of wetlands are associated with declines in helminth richness and abundance, but that alteration of wetland water quality through eutrophication or pesticide contamination may facilitate the transmission of certain parasite taxa when they are present at wetlands. Although additional research is needed to quantify the negative effects of parasitism on frog populations, efforts to reduce inputs of agrochemicals into wetlands to limit larval trematode infections may be warranted, given the current high rates of amphibian declines and extinction events.

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Section: Data Analysesmentioning

confidence: 99%

Effects of wetland vs. landscape variables on parasite communities ofRana pipiens: links to anthropogenic factors

Schotthoefer

Rohr

Cole

et al. 2011

Ecological Applications

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“…The species is estimated to have suffered extreme range contractions, and there is interest in identifying features of habitats that allow successful persistence of this species (Beasley et al . ) and could be used to develop conservation and management strategies. Therefore, the use of our false‐positive model is advised, considering that the standard model overestimated the number of occupied routes by 67%.…”

Section: Discussionmentioning

confidence: 99%

“…Similarly, the range for A. crepitans is restricted to the south-east of the Appalachian Mountains, and the posterior mean for occupancy was similarly estimated to be low (w = 0Á11) in our study. The species is estimated to have suffered extreme range contractions, and there is interest in identifying features of habitats that allow successful persistence of this species (Beasley et al 2005) and could be used to develop conservation and management strategies. Therefore, the use of our false-positive model is advised, considering that the standard model overestimated the number of occupied routes by 67%.…”

Section: Discussionmentioning

confidence: 99%

Uncertainty in biological monitoring: a framework for data collection and analysis to account for multiple sources of sampling bias

2016

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Summary Biological monitoring programmes are increasingly relying upon large volumes of citizen‐science data to improve the scope and spatial coverage of information, challenging the scientific community to develop design and model‐based approaches to improve inference. Recent statistical models in ecology have been developed to accommodate false‐negative errors, although current work points to false‐positive errors as equally important sources of bias. This is of particular concern for the success of any monitoring programme given that rates as small as 3% could lead to the overestimation of the occurrence of rare events by as much as 50%, and even small false‐positive rates can severely bias estimates of occurrence dynamics. We present an integrated, computationally efficient Bayesian hierarchical model to correct for false‐positive and false‐negative errors in detection/non‐detection data. Our model combines independent, auxiliary data sources with field observations to improve the estimation of false‐positive rates, when a subset of field observations cannot be validated a posteriori or assumed as perfect. We evaluated the performance of the model across a range of occurrence rates, false‐positive and false‐negative errors, and quantity of auxiliary data. The model performed well under all simulated scenarios, and we were able to identify critical auxiliary data characteristics which resulted in improved inference. We applied our false‐positive model to a large‐scale, citizen‐science monitoring programme for anurans in the north‐eastern United States, using auxiliary data from an experiment designed to estimate false‐positive error rates. Not correcting for false‐positive rates resulted in biased estimates of occupancy in 4 of the 10 anuran species we analysed, leading to an overestimation of the average number of occupied survey routes by as much as 70%. The framework we present for data collection and analysis is able to efficiently provide reliable inference for occurrence patterns using data from a citizen‐science monitoring programme. However, our approach is applicable to data generated by any type of research and monitoring programme, independent of skill level or scale, when effort is placed on obtaining auxiliary information on false‐positive rates.

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“…One exception, however, is the Blanchard's cricket frog ( Acris blanchardi ), whose range coincides with areas of heavy pesticide use in the United States Midwest. Reports suggest that cricket frogs are experiencing a range constriction as well as population losses throughout portions of their range (Lannoo et al ; Lannoo ; Gray and Brown ; Beasley et al ; Lehtinen and Skinner ; Burdick and Swanson ). Although a slew of hypotheses have been suggested to explain this species’ decline, including changes in terrestrial and aquatic habitats, parasites and disease, and contamination (Lannoo ; Beasley et al ; Steiner and Lehtinen ; Lehtinen and Skinner ), there is not a clear causal factor for widespread cricket frog declines, despite a number of studies exploring this question (e.g., Lehtinen and Skinner ; McCallum ; Youngquist et al ).…”

Section: Introductionmentioning

confidence: 99%

“…Reports suggest that cricket frogs are experiencing a range constriction as well as population losses throughout portions of their range (Lannoo et al ; Lannoo ; Gray and Brown ; Beasley et al ; Lehtinen and Skinner ; Burdick and Swanson ). Although a slew of hypotheses have been suggested to explain this species’ decline, including changes in terrestrial and aquatic habitats, parasites and disease, and contamination (Lannoo ; Beasley et al ; Steiner and Lehtinen ; Lehtinen and Skinner ), there is not a clear causal factor for widespread cricket frog declines, despite a number of studies exploring this question (e.g., Lehtinen and Skinner ; McCallum ; Youngquist et al ). However, experimental field studies have suggested that cricket frogs may be sensitive to contaminants, with unexpected strong negative effects on survival or juvenile recruitment in some cases (Ade and Boone ; Puglis and Boone ; Hoskins and Boone , 2018), although at concentrations generally above expected environmental concentrations.…”

Section: Introductionmentioning

confidence: 99%

An amphibian with a contracting range is not more vulnerable to pesticides in outdoor experimental communities than common species

Boone

2018

Enviro Toxic and Chemistry

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In areas with heavy pesticide use, it is easy to attribute population declines to environmental contamination. The Blanchard's cricket frogs (Acris blanchardi) is an amphibian experiencing declines and range contractions across its distribution in the Midwest Corn Belt (USA). Experimental studies suggest that cricket frogs are sensitive to pesticides, but there are few studies examining this species' susceptibility to contaminants in realistic environments or comparing relative impacts with other anuran species. I reared 3 summer breeding anurans in outdoor mesocosms posthatching through metamorphosis to examine the effects of 2 insecticides (imidacloprid and carbaryl) and 1 herbicide (glyphosate with polyoxyethylene tallow amine) on larval development and metamorphosis. Cricket frogs were positively affected by insecticide exposure, likely a result of changes in the food web that increased food abundance. However, metamorphosis of green frogs (Lithobates clamitans) and gray tree frogs (Hyla chrysoscelis) appeared unaffected by pesticide exposure. The results of the present study suggest that the impacts of pesticides alone are unlikely to have population-level impacts for the anurans examined. Environ Toxicol Chem 2018;37:2699-2704. © 2018 SETAC.

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Risk Factors and Declines in Northern Cricket Frogs (Acris crepitans)

Cited by 25 publications

References 0 publications

Effects of wetland vs. landscape variables on parasite communities ofRana pipiens: links to anthropogenic factors

Effects of wetland vs. landscape variables on parasite communities ofRana pipiens: links to anthropogenic factors

Uncertainty in biological monitoring: a framework for data collection and analysis to account for multiple sources of sampling bias

An amphibian with a contracting range is not more vulnerable to pesticides in outdoor experimental communities than common species

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