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1292 record(s) found.

Papers & Reports In situ effects of pesticides on amphibians in the Sierra Nevada

Authors: D W Sparling; John Bickham; D Cowman; Gary M Fellers; L Lacher; C W Matson; L L McConnell

Date: 2015-03 | Outlet: Ecotoxicology 24:262-278

For more than 20 years, conservationists have agreed that amphibian populations around the world are declining. Results obtained through laboratory or mesocosm studies and measurement of contaminant concentrations in areas experiencing declines have supported a role of contaminants in these declines. The current study examines the effects of contaminant exposure to amphibians in situ in areas actually experiencing declines. Early larval Pseudacris regilla were translocated among Lassen Volcanic, Yosemite and Sequoia National Parks, California, USA and caged in wetlands in 2001 and 2002 until metamorphosis. Twenty contaminants were identified in tadpoles with an average of 1.3–5.9 (maximum = 10) contaminants per animal. Sequoia National Park, which had the greatest variety and concentrations of contaminants in 2001, also had tadpoles that experienced the greatest mortality, slowest developmental rates and lowest cholinesterase activities. Yosemite and Sequoia tadpoles and metamorphs had greater genotoxicity than those in Lassen during 2001, as determined by flow cytometry. In 2001 tadpoles at Yosemite had a significantly higher rate of malformations, characterized as hemimelia (shortened femurs), than those at the other two parks but no significant differences were observed in 2002. Fewer differences in contaminant types and concentrations existed among parks during 2002 compared to 2001. In 2002 Sequoia tadpoles had higher mortality and slower developmental rates but there was no difference among parks in cholinesterase activities. Although concentrations of most contaminants were below known lethal concentrations, simultaneous exposure to multiple chemicals and other stressors may have resulted in lethal and sublethal effects.

Papers & Reports Movement and habitat selection of the western spadefoot (Spea hammondii) in southern California

Authors: Katherine L Baumberger; M . Eitzel; M Kirby; M Horn

Date: 2019-10-03 | Outlet: PLoS ONE 14(10): e0222532.

Agricultural activity, urban development and habitat alteration have caused the disappearance of the western spadefoot (Spea hammondii) from 80% of its range in southern California. Despite the western spadefoot’s continuing decline, little research has been conducted on its natural history. The home range of adult spadefoot is unknown, and their use of upland habitat is poorly understood. Both of these factors are important for the long-term conservation of the species because adult spadefoot spend the majority of their lives away from breeding pools. During the course of this study, radio transmitters were surgically implanted in 15 spadefoot and their movements and habitat use recorded for an average of 272 days. During that time, rain was the only significant predictor of spadefoot movement. The overall mean distance moved between burrow sites was https://17.56 m (SD ± https://23.96 m, N = 184). The mean distance moved away from the breeding pools was https://40.04 m (SD ± https://37.42, N = 200). The maximum distance moved away from the breeding pools was https://261.99 m. The amount of clay was the only predictor of spadefoot burrow locations, with spadefoot burrowing in friable soil with significantly less clay than random non-spadefoot sites. This study enhances our understanding of a little-studied species and will assist land managers in the formation of effective management plans for the spadefoot.

Papers & Reports Performance of occupancy estimators when basic assumptions are not met: a test with field data where truth is known.

Authors: David AW Miller; Larissa L Bailey; Evan HC Grant; Brett T McClintock; L A Wier; T R Simons

Outlet: Methods in Ecology and Evolution xx:xxx-xxx

Populations are rarely censused. Instead observations are affected by incomplete detection, misclassification, and detection heterogeneity that results from human and environmental constraints. Though numerous methods have been developed to deal with observational uncertainty, validation under field conditions are rare because truth is rarely known. We present the most comprehensive test of occupancy methods to date, using more than 33,000 auditory call observations collected under standard field conditions but where the true occupancy status of sites was known. Basic occupancy estimation approaches were biased when two key assumptions were not met: that no false positives occur and that no unexplained heterogeneity in detection parameters occurs. The greatest bias occurred for dynamic parameters (i.e., local colonization and extinction) and in many cases the degree of inaccuracy would render results largely useless. We examined three approaches to increase adherence or relax these assumptions: modifying the sampling design, employing estimators that account for false positive detections, and using covariates to account for site-level heterogeneity in both false negative and false positive detection probabilities. We demonstrate that bias can be substantially reduced by modifications to sampling methods and by using estimators that simultaneously account for false positive detections and site-level covariates to explain heterogeneity. Our results demonstrate that even small probabilities of misidentification and among-site detection heterogeneity can have severe effects on estimator reliability if ignored. We challenge researchers to place greater attention to both heterogeneity and false positives when designing and analyzing occupancy studies and provide 9 specific guidelines for design, implementation, and analysis of occupancy studies to meet this challenge.

News & Stories 2015 ARMI annual meeting

Authors: Erin Muths

December 10, 2014

This year the annual ARMI meeting was a no-host event held outside of Denver in early December. This short meeting focused on in-depth discussions about management questions, basic science, and cross-discipline, integrative research to address amphibian declines. Topics included disease, methodologies, web-site and data management advances, and outreach.

Papers & Reports Monitoring Yellowstone’s wetlands: can long-term monitoring help us understand their future?

Authors: Andrew M Ray; A Sepulveda; Blake R Hossack; Debra A Patla; D Thoma; Robert Al-Chokhachy

Date: 2015 | Outlet: Yellowstone Science 23:44-53

Papers & Reports Population genetic structure and disease in montane boreal toads: Why does chytridiomycosis infection increase with heterozygosity?

Authors: Brett R Addis; W H Lowe; Blake R Hossack; Fred W Allendorf

Date: 2015 | Outlet: Conservation Genetics DOI: 10.1007/s10592-015-0704-6.

Papers & Reports Environmental DNA: Can it improve our understanding of biodiversity on NPS lands?

Authors: Andrew M Ray; A Sepulveda; Blake R Hossack; Debra A Patla; K Legg

Date: 2014 | Outlet: Park Science 31:118

Papers & Reports Using occupancy models to accommodate uncertainty in the interpretation of aerial photograph data: status of beaver in central Oregon, USA

Authors: Christopher A Pearl; Michael J Adams; P K Haggerty; L Urban

Date: 2015-02-27 | Outlet: Wildlife Society Bulletin 39:1944-1963

Beavers (Castor canadensis) influence habitat for many species and pose challenges in developed landscapes. They are increasingly viewed as a cost?efficient means of riparian habitat restoration and water storage. Still, information on their status is rare, particularly in western North America. We used aerial photography to evaluate changes in beaver occupancy between 1942–1968 and 2009 in upper portions of 2 large watersheds in Oregon, USA. We used multiple observers and occupancy modeling to account for bias related to photo quality, observers, and imperfect detection of beaver impoundments. Our analysis suggested a slightly higher rate of beaver occupancy in the upper Deschutes than the upper Klamath basin. We found weak evidence for beaver increases in the west and declines in eastern parts of the study area. Our study presents a method for dealing with observer variation in photo interpretation and provides the first assessment of the extent of beaver influence in 2 basins with major water?use challenges. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Papers & Reports The Source, Discharge, and Chemical Characteristics of Selected Springs, and the Abundance and Health of Associated Endemic Anuran Species in the Mojave Network of Parks

Authors: P Martin; R Schroeder; G Smith; A Flint; Elizabeth A Gallegos; Robert N Fisher

Date: 2015-05-08 | Outlet: USGS Scientific Investigations Report 2015-5027

Hydrological and biological investigations were done during 2005 and 2006 in cooperation with the U.S. National Park Service to investigate the source, discharge, and chemical characteristics of selected springs and the abundance and health of endemic anuran (frog and toad) species at Darwin Falls in Death Valley National Park, Piute Spring in Mojave National Preserve, and Fortynine Palms Oasis in Joshua Tree National Park. Discharge from the springs at these sites sustains isolated riparian habitats in the normally dry Mojave Desert. Data were collected on water quantity (discharge) and quality, air and water temperature, and abundance and health of endemic anuran species. In addition, a single survey of the abundance and health of endemic anuran species was completed at Rattlesnake Canyon in Joshua Tree National Park. Results from this study were compared to limited historical data, where they exist, and can provide a baseline for future hydrological and biological investigations to evaluate the health and sustainability of the resource and its response to changing climate and increasing human use.

Radiocarbon dating of the water yielded estimated ages of about 7,000 years at Piute Spring and about 3,000 years at Darwin Spring, and tritium-helium-3 dating indicated an age of less than 2 years at Fortynine Palms Oasis. Stable hydrogen-isotope ratios were used to interpret an average altitude of recharge of 2,348 meters for Darwin Spring (about 1,415 meters higher than the altitude of Darwin Spring), 1,668 meters for Piute Spring (about 766 meters higher than the altitude of Piute Spring), and 1,400 meters for the Upper Pool at Fortynine Palms Oasis (about 543 meters higher than the altitude of the Upper Pool). Water-quality data collected for this study did not appear to be sensitive to trends in precipitation or seasonality in the Darwin Falls and Piute Spring study areas; however, it was sensitive to trends in Fortynine Palms Oasis where salinity increased by more than 10 percent during the 2 years of this study. Such a rapid response is consistent with the comparatively short travel time of less than 2 years from recharge to discharge at Fortynine Palms Oasis. Of the 14 trace elements analyzed, only concentrations of uranium at Fortynine Palms Oasis and arsenic at Darwin Spring were above drinking water standards; both constituents are derived from natural sources in the drainage basin and, therefore, are likely to have accumulated as a result of natural processes.

Endemic anuran species were surveyed at Darwin Falls for the western toad [Anaxyrus boreas] and the red-spotted toad [Anaxyrus punctatus], at Piute Spring for the red-spotted toad, and at Fortynine Palms Oasis for the red-spotted toad and California treefrog [Pseudacris cadaverina]. Historically, red-spotted toads were at the edge of their range at Darwin Falls, but they were not detected during this study and have not been detected since the early 1980s. The 2006 western toad population at Darwin Falls was estimated at 381 adults (95-percent confidence interval [CI] of 314–482). The population of red-spotted toads at Piute Spring was estimated at 1,153 adults (95-percent CI of 935–1,503). However, an elevated rate of abnormalities (approximately 5 percent) was recorded in red-spotted toads as well as the presence of the chytrid fungus,[Bactrochochytrium dendrobatidis], at Piute Spring. In Joshua Tree National Park, the California treefrog now occupies only three of the seven historically occupied drainages. Populations of California treefrogs at Fortynine Palms Oasis have declined more than 50 percent from 288 in 1969–71 to 109 in 2006. A similar decline was observed in the populations of red-spotted toads at Fortynine Palms Oasis from 300 adults in 1969–71 to 155 adults (95-percent CI of 90–139) in 2006. The red-spotted toads at Fortynine Palms Oasis also exhibited the presence of [Bactrochochytrium dendrobatidis].

Papers & Reports Modeling false positive detections in species occurrence data under different study designs

Authors: Thierry C Chambert; David AW Miller; J D Nichols

Outlet: Ecology

The occurrence of false positive detections in presence-absence data, even when they occur infrequently, can lead to severe bias when estimating species occupancy patterns. Building upon previous efforts to account for this source of observational error (Royle & Link 2006; Miller et al. 2011, 2013), we establish a general framework to model false positives in occupancy studies and extend existing modeling approaches to encompass a broader range of sampling designs. Specifically, we identified three common sampling designs that are likely to cover most scenarios encountered by researchers. The different designs all include ambiguous detections, as well as some known-truth data, but their modeling differs in the level of the model hierarchy at which the known-truth information is incorporated (site-level or observation-level). For each model, we provide the likelihood, as well as R and BUGS code needed for implementation. We also establish a clear terminology and provide guidance to help choosing the most appropriate design and modeling approach.

Papers & Reports Glyphosate and its degradation product AMPA occur frequently and widely in U.S. soils, surface water, groundwater, and precipitation

Authors: William A Battaglin; M Meyer; Kathryn M Kuivila; J Dietze

Date: 2014 | Outlet: Journal of the American Water Resources Association 50(2): 275-290.

Glyphosate use in the US increased from less than 5,000 to more than 80,000 metric tons per year between 1987 and 2007. Glyphosate is popular due to its ease of use on soybean, cotton and corn crops that are genetically modified to tolerate it, utility in no-till farming practices, utility in urban areas, and the perception that it has low toxicity and little mobility in the environment. This compilation is the largest and most comprehensive assessment of the environmental occurrence of glyphosate and AMPA in the US conducted to date, summarizing the results of 3,732 water and sediment and 1,018 quality-assurance samples collected between 2001 and 2010 from 38 States. Results indicate that glyphosate and AMPA are usually detected together, mobile, and occur widely in the environment. Glyphosate was detected without AMPA in only 2.3% of samples, whereas AMPA was detected without glyphosate in 17.9% of samples. Glyphosate and AMPA were detected frequently in soils and sediment, ditches and drains, precipitation, rivers, and streams; and less frequently in lakes, ponds, and wetlands; soil water; and groundwater. Concentrations of glyphosate were below levels of concern for humans or wildlife; however, pesticides are often detected in mixtures. Ecosystem effects of chronic low-level exposures to pesticide mixtures are uncertain. The environmental health risk of low-level detections of glyphosate, AMPA, and associated adjuvants and mixtures remain to be determined.

News & Stories ARMI research on amphibian chytrid fungus occupancy and detection in wetlands featured in the Environmental Monitor

Authors: T Chestnut

November 03, 2014

The amphibian chytrid fungus is an aquatic fungus implicated as a contributor to amphibian declines worldwide. Most research has focused on the dynamics of the pathogen in its amphibian hosts, with little emphasis on the ecology of the fungus in the environment. Therefore, we investigated patterns of amphibian chytrid fungus occupancy and density in amphibian habitats using occupancy models, powerful tools for estimating site occupancy and detection probability. This study provided evidence that the fungus occurs in the environment year-round, and its density varies seasonally. We detected the amphibian chytrid fungus in 47% of sites sampled, but estimated that it occupied 61% of sites, highlighting the importance of accounting for imperfect detection. When the amphibian chytrid fungus was present, there was a 95% chance of detecting it with four samples of 600 ml of water or five samples of 60 mL. Our findings provide important baseline information to advance the study of Bd disease ecology, and advance our understanding of amphibian exposure to free-living Bd in aquatic habitats over time.

For more coverage from Environmental Monitor, follow the jump: http://www.fondriest.com/news/new-amphibian-chytrid-fungus-tests-ease-search-wide-ranging-frog-disease.htm

News & Stories ARMI recognized!

Authors: Michael J Adams

October 31, 2014

The 2014 Special Recognition Award from The Wildlife Society's Biometrics Working Group was presented to the Amphibian Research and Monitoring Initiative. The award is meant to recognize a group or an individual that has made an outstanding contribution to the development and application of quantitative methods to the fields of wildlife science and management. This year the award is presented to the Amphibian Research and Monitoring Initiative (ARMI) implemented by the U.S. Geological Survey and the U.S. Fish and Wildlife Service. ARMI has shown a deep appreciation for biometrical methods and their importance for drawing inferences about biological populations and communities. Most significantly ARMI propelled forward the development of a class of models (occupancy) that is now used worldwide by ecologists and conservation biologists. This funding support was largely responsible for dozens of papers on the development of occupancy modeling and for the 2006 book (MacKenzie et al. 2006, Academic Press; see Acknowledgements in this book) summarizing developments to that time. This development has not only been useful to ARMI projects, but has also benefited the worldwide community of animal ecologists, wildlife managers, and the field of biometrics.

News & Stories ARMI recognized!

Authors: Michael J Adams

October 31, 2014

Papers & Reports The effects of hydropattern and predator communities on amphibian occupancy

Authors: Staci M Amburgey; Larissa L Bailey; M Murphy; Erin Muths; W C Funk

Date: 2014-09-23 | Outlet: Canadian Journal of Zoology

Complex, interactive ecological constraints regulate species distributions, and understanding these factors is crucial for predicting species persistence. We used occupancy analysis, which corrects for imperfect detection, to test the importance of abiotic and biotic habitat and landscape factors on probability of occupancy by boreal chorus frog (Pseudacris maculata; Agassiz 1850) tadpoles. We hypothesized that hydropattern and predators are primarily important as they affect desiccation and predation risk and can interact in ways difficult to predict. We surveyed 62 wetland sites across an elevational gradient in Colorado, USA and modeled patterns in P. maculata occupancy. Tadpoles were most frequently present in intermediate hydropattern systems with lower desiccation risk and no predatory fish due to occasional drying. P. maculata occupancy had a strong negative relationship with fish presence while tadpoles, odonate larvae and tiger salamanders (Ambystoma mavortium; Baird 1850) frequently co-occurred. Dry seasonal conditions will likely result in fewer intermediate hydropattern ponds available for amphibian breeding. We hypothesize that this will force P. maculata to breed in habitats with fish. As habitats shrink, predators that co-occur with P. maculata are expected to concentrate in the remaining habitat and increase predation risk for developing tadpoles (assuming predators are similarly constricted in their habitat use as amphibians are).

Papers & Reports Potential reduction in terrestrial salamander ranges associated with Marcellus shale development

Authors: Adrianne B Brand; A mb Wiewel; Evan HC Grant

Outlet: Biological Conservation

Natural gas production from the Marcellus shale is rapidly increasing in the northeastern United States. Most of the endemic terrestrial salamander species in the region are classified as ‘globally secure’ by the IUCN, primarily because much of their ranges include state- and federally protected lands, which have been presumed to be free from habitat loss. However, the proposed and ongoing development of the Marcellus gas resources may result in significant range restrictions for these and other terrestrial forest salamanders. To begin to address the gaps in our knowledge of the direct impacts of shale gas development, we developed occurrence models for five species of terrestrial plethodontid salamanders found largely within the Marcellus shale play. We predicted future Marcellus shale development under several scenarios. Under scenarios of 10000, 20000, and 50000 new gas wells, we predict 4%, 8%, and 20% forest loss, respectively, within the play. Predictions of habitat loss vary among species, but in general, Plethodon electromorphus and P. wehrlei are predicted to lose the greatest proportion of forested habitat within their ranges if future Marcellus predictions are based on characteristics of the shale play. If predictions are based on current well locations, P. richmondi is predicted to lose the greatest proportion of habitat. Models showed high uncertainty in species’ ranges and emphasize the need for distribution data collected by widespread and repeated, randomized surveys.

Papers & Reports Short-term occupancy and abundance dynamics of the Oregon Spotted Frog (Rana pretiosa) across its core range

Authors: Michael J Adams; Christopher A Pearl; Brome McCreary; Stephanie K Galvan

Date: 2014-11-03 | Outlet: U.S. Geological Survey Open-File Report 2014-1230

The Oregon spotted frog (Rana pretiosa) occupies only a fraction of its original range and is listed as Threatened under the Endangered Species Act. We surveyed 93 sites in a rotating panel frame design (2010–13) in the Klamath and Deschutes Basins, Oregon, which encompass most of the species’ core extant range. Oregon spotted frogs are decreasing in probability of both site occupancy and abundance. We did not find an association between the probability that Oregon spotted frogs disappear from a site (local extinction) and any of the variables hypothesized to affect Oregon spotted frog occupancy. This 4-year study provides baseline data, but the 4-year period was too short to draw firm conclusions about current (2014) trends. Further study is essential to understand how habitat changes and management practices relate to the status and trends of this species.

Papers & Reports Using monitoring data to map amphibian breeding hotspots and describe wetland vulnerability in Yellowstone and Grand Teton National Parks

Authors: Andrew M Ray; A Sepulveda; Blake R Hossack; Debra A Patla; K Legg

Date: 2014 | Outlet: Park Science 31:112-119

Amphibians have been selected as a “vital sign” by several
National Park Service (NPS) Inventory and Monitoring (I&M)
networks. An eight-year amphibian monitoring data set provided
opportunities to examine spatial and temporal patterns in
amphibian breeding richness and wetland desiccation across
Yellowstone and Grand Teton National Parks. Amphibian
breeding richness was variable across both parks, and only 4 of
31 permanent monitoring catchments contained all four widely
distributed species. Annual breeding richness was also variable
through time and fl uctuated by as much as 75% in some years and
catchments. Wetland desiccation was also documented across the
region, but alone did not explain variations in amphibian richness.
High annual variability across the region emphasizes the need for
multiple years of monitoring to accurately describe amphibian
richness and wetland desiccation dynamics.

Papers & Reports Reproductive strategy and carry-over effects for species with complex life histories.

Authors: Adam W Green; Larissa L Bailey

Outlet: Population Ecology

Papers & Reports Indicators of the Statuses of Amphibian Populations and Their Potential for Exposure to Atrazine in Four Midwestern U.S. Conservation Areas

Authors: Walt J Sadinski; Mark F Roth; T Hayes; P M Jones; A L Gallant

Date: 2014-09-12 | Outlet: PLoS ONE 9(9): e107018. doi:10.1371/journal.pone.0107018

Extensive corn production in the midwestern United States has physically eliminated or fragmented vast areas of historical amphibian habitat. Midwestern corn farmers also apply large quantities of fertilizers and herbicides, which can cause direct and indirect effects on amphibians. Limited field research regarding the statuses of midwestern amphibian populations near areas of corn production has left resource managers, conservation planners, and other stakeholders needing more information to improve conservation strategies and management plans. We repeatedly sampled amphibians in wetlands in four conservation areas along a gradient of proximity to corn production in Illinois, Iowa, Minnesota, and Wisconsin from 2002 to 2005 and estimated site occupancy. We measured frequencies of gross physical deformities in recent metamorphs and triazine concentrations in the water at breeding sites. We also measured trematode infection rates in kidneys of recently metamorphosed Lithobates pipiens collected from nine wetlands in 2003 and 2004. We detected all possible amphibian species in each study area. The amount of nearby row crops was limited in importance as a covariate for estimating site occupancy. We observed deformities in <5% of metamorphs sampled and proportions were not associated with triazine concentrations. Trematode infections were high in metamorphs from all sites we sampled, but not associated with site triazine concentrations, except perhaps for a subset of sites sampled in both years. We detected triazines more often and in higher concentrations in breeding wetlands closer to corn production. Triazine concentrations increased in floodplain wetlands as water levels rose after rainfall and were similar among lotic and lentic sites. Overall, our results suggest amphibian populations were not faring differently among these four conservation areas, regardless of their proximity to corn production, and that the ecological dynamics of atrazine exposure were complex.