Interactions between Eastern Newts and Wood Frogs in an anthropogenically altered wetland system in eastern Kentucky

A key characteristic of the ridge-top ecosystem in eastern Kentucky is the presence of ephemeral wetlands. Ephemeral wetlands of the ridge-top ecosystem support an amphibian community assemblage characterized by species with short larval periods (e.g., Wood Frogs [Lithobates sylvaticus] and Marbled Salamanders [Ambystoma opacum]). Over the last 25 years, hundreds of wetlands have been constructed within the ridge-top ecosystem as permanent water sources for wildlife (i.e., game species). Consequently, the modified ridge-top ecosystem contains hundreds of constructed wetlands interspersed among natural, ephemeral wetlands. The altered ecosystem has been colonized by several amphibian species with larval periods that require a long hydroperiod (e.g., Eastern Newts [Notophthalmus viridescens], American Bullfrogs [L. catesbeianus], and Green Frogs [L. clamitans]). The new members of the amphibian community assemblage are top predators known to consume various amphibian life stages. Some ephemeral wetland species will breed in constructed wetlands; thus, the recent species additions could have negative impacts on the amphibian species historically associated with the ridge-top ecosystem. My study objectives were to: (1) determine if species of the ephemeral wetland and constructed wetland amphibian communities interact, and (2) evaluate the direction of species interactions (i.e., positive or negative impacts) within the communities. I selected Eastern Newts and Wood Frogs as representatives of the constructed and natural amphibian communities, respectively. I sampled six constructed and six ephemeral wetlands throughout 2013 and 2014. I counted Wood Frog egg masses and estimated survival bi-weekly throughout the breeding season (February-May) at each wetland in each year. I sampled Eastern Newt populations once per month in May, July, September, and November 2013 and January-May 2014. I measured (i.e., SVL, Mass, and sex) newt captures to determine body condition. Data were analyzed using Wilcoxon Mann-Whitney U-tests and stepwise regression models. Eastern Newts and Wood Frogs interact within constructed wetlands. Wood Frog reproductive success was negatively impacted when eggs were laid in constructed wetlands: eggs were consumed (15% - 70%) a higher number of Wood Frog larvae were found in natural wetlands than in constructed wetlands (W = 186.00, p = 0.039). Eastern Newts benefited from Wood Frog presence: newts in constructed wetlands with Wood Frog eggs had higher body condition (W = 402,474.00, p \u3c 0.001). The creation of permanent constructed wetlands has allowed for colonization by amphibians that require long hydroperiods and are top predators. Wetland construction techniques need to be altered to have a more ephemeral hydroperiod, which can limit predation pressure and allow for use by ephemeral breeders. Understanding the impacts of how amphibian species interact as habitat loss and modification increase will continue to be critical for amphibian conservation

Characterizing the Online Learning Landscape: {W}hat and How People Learn Online

Hundreds of millions of people learn something new online every day. Simultaneously, the study of online education has blossomed within the human computer interaction community, with new systems, experiments, and observations creating and exploring previously undiscovered online learning environments. In this study we endeavor to characterize this entire landscape of online learning experiences using a national survey of 2260 US adults who are balanced to match the demographics of the U.S. We examine the online learning resources that they consult, and we analyze the subjects that they pursue using those resources. Furthermore, we compare both formal and informal online learning experiences on a larger scale than has ever been done before, to our knowledge, to better understand which subjects people are seeking for intensive study. We find that there is a core set of online learning experiences that are central to other experiences and these are shared among the majority of people who learn online. We conclude by showing how looking outside of these core online learning experiences can reveal opportunities for innovation in online education

Species Interactions in Constructed Wetlands Result in Population Sinks for Wood Frogs (Lithobates sylvaticus) while Benefitting Eastern Newts (Notophthalmus viridescens)

Wetland construction has been used as a tool to mitigate wetland loss, but constructed wetlands might not provide the same functions as natural wetlands. Hundreds of long-hydroperiod wetlands have been constructed within the Daniel Boone National Forest, Kentucky, in a ridge-top ecosystem where natural wetlands dry annually (i.e., have short hydroperiods). The constructed wetlands have been colonized by several amphibian species not historically associated with this ecosystem and that could have negative impacts on native amphibian species. We compared wood frog (Lithobates sylvaticus) reproductive success at constructed and natural wetlands and benefits of wood frog presence in constructed wetlands to eastern newts (Notophthalmus viridescens). Wood frog reproductive success was zero when eggs were laid in constructed wetlands: 7–70 % of eggs were consumed and no wood frog larvae were found. Eastern newts, present at all constructed wetlands, benefited from wood frog presence, i.e., newts in constructed wetlands with wood frog eggs had higher body condition than newts in natural wetlands. Wetland construction techniques should be altered so their hydrology mimics that of natural wetlands to support historically occurring species. Understanding the influence of species interactions, as habitat loss and modification increase, will continue to be critical for amphibian conservation. Keywords Ephemeral wet

System analysis approach to deriving design criteria (loads) for Space Shuttle and its payloads. Volume 1: General statement of approach

Space shuttle, the most complex transportation system designed to date, illustrates the requirement for an analysis approach that considers all major disciplines simultaneously. Its unique cross coupling and high sensitivity to aerodynamic uncertainties and high performance requirements dictated a less conservative approach than those taken in programs. Analyses performed for the space shuttle and certain payloads, Space Telescope and Spacelab, are used a examples. These illustrate the requirements for system analysis approaches and criteria, including dynamic modeling requirements, test requirements control requirements and the resulting design verification approaches. A survey of the problem, potential approaches available as solutions, implications for future systems, and projected technology development areas are addressed

System analysis approach to deriving design criteria (Loads) for Space Shuttle and its payloads. Volume 2: Typical examples

The achievement of an optimized design from the system standpoint under the low cost, high risk constraints of the present day environment was analyzed. Space Shuttle illustrates the requirement for an analysis approach that considers all major disciplines (coupling between structures control, propulsion, thermal, aeroelastic, and performance), simultaneously. The Space Shuttle and certain payloads, Space Telescope and Spacelab, are examined. The requirements for system analysis approaches and criteria, including dynamic modeling requirements, test requirements, control requirements, and the resulting design verification approaches are illustrated. A survey of the problem, potential approaches available as solutions, implications for future systems, and projected technology development areas are addressed

Upland Habitat Quality and Historic Landscape Composition Influence Genetic Variation of a Pond-Breeding Salamander

Understanding the temporal and spatial scale at which habitat alteration impacts populations is important for conservation and management. Amphibians have declined more than other vertebrates, and pond-breeding species are particularly susceptible to habitat loss and fragmentation because they have terrestrial and aquatic life stages. One approach to management of pond-breeding species is protection of core upland habitat surrounding the breeding pond. We used genetic variation as an indicator of population status in a common amphibian species, spotted salamanders (Ambystoma maculatum), to determine how amount of suitable upland habitat relates to population status in the greater Charlotte, North Carolina, USA metropolitan area. We developed candidate models to evaluate the relative influence of historical and contemporary forested habitat availability on population genetic variation at two spatial scales of upland area (164 m and 2000 m) at four time intervals over the past seven decades (1938, 1978, 1993, 2005). We found that historical land cover best predicted contemporary allelic richness. Inbreeding coefficient and observed heterozygosity were not effectively predicted by forest cover at either spatial or temporal scales. Allelic richness was best predicted at the smaller spatial scale in the 1993 time interval. Predicting and understanding how future landscape configuration affects genetic variation of common and rare species is imperative for the conservation of amphibian and other wildlife populations

Residential radon-222 exposure and lung cancer: exposure assessment methodology

Although occupational epidemiological studies and animal experimentation provide strong evidence that radon-222 (222Rn) progeny exposure causes lung cancer, residential epidemiological studies have not confirmed this association. Past residential epidemiological studies have yielded contradictory findings. Exposure misclassification has seriously compromised the ability of these studies to detect whether an association exists between 222Rn exposure and lung cancer. Misclassification of 222Rn exposure has arisen primarily from: 1) detector measurement error; 2) failure to consider temporal and spatial 222Rn variations within a home; 3) missing data from previously occupied homes that currently are inaccessible; 4) failure to link 222Rn concentrations with subject mobility; and 5) measuring 222Rn gas concentration as a surrogate for 222Rn progeny exposure. This paper examines these methodological dosimetry problems and addresses how we are accounting for them in an ongoing, population-based, case-control study of 222Rn and lung cancer in Iowa