Artificial shelters show great promise as novel, non-invasive tools for studying hellbenders, but their use thus far has faced several challenges. During initial trials in multiple river networks, artificial shelters routinely became blocked by sediment and dislodged during high stream discharge events, and were rarely used by hellbenders. We sought to determine whether these complications could be overcome via alternative shelter design, placement, and maintenance. Between 2013 and 2018, we deployed 438 artificial shelters of two different designs across ten stream reaches and three rivers in the upper Tennessee River Basin. We assessed evidence for several hypotheses, postulating broadly that the availability, stability, and use of artificial shelters by hellbenders would depend on how shelters were constructed, deployed, and/or maintained. We found that maintaining shelters at least once every 40 days limited sediment blockage, and building ~ 40 kg shelters with 3-4 cm thick walls and recessed lids improved their stability during high discharge events. Additionally, we found that hellbenders most frequently occupied and nested in artificial shelters when they were deployed in deeper (~50+ cm) portions of reaches with high adult hellbender densities. Our results suggest that artificial shelters can serve as effective tools for studying hellbenders when designed, deployed, and maintained with these advancements, but also highlight some limitations of their use. / Master of Science / Hellbenders are large, fully-aquatic salamanders that live primarily in cool, rocky, swift-flowing streams in portions of Appalachia and the lower Midwest. They are imperiled across most of their native range due to human-caused habitat degradation, but their declines, conservation needs, and population status have historically been difficult to study due to the fact that they spend the majority of their lives beneath large, often inaccessible boulders. While these boulders are sometimes possible to lift, doing so can disturb critical hellbender habitat. Therefore, alternate, less invasive hellbender sampling methods are necessary in order to improve knowledge about their conservation status and needs. Artificial shelters, which are large, hollow, concrete structures that mimic natural boulder crevices and feature removable lids, show promise as a novel, innovative tool for non-invasively studying hellbenders. However, initial trials of these shelters have yielded mixed results, with shelters often becoming swept away and destroyed during floods, becoming blocked by sand and sediment and thus inaccessible to hellbenders, or simply not being used by hellbenders when accessible. We sought to determine whether these complications could be overcome by optimizing the way that shelters were constructed, deployed, and maintained in streams inhabited by hellbenders. Between 2013 and 2018, we deployed 438 artificial shelters of two different designs across ten stream reaches and three rivers in the upper Tennessee River Basin. Using multiple analyses, we tested one broad overall hypothesis: that the efficacy of using artificial shelters to study hellbenders would depend on how they were constructed, how frequently they were maintained, and where they were placed in the stream. We found that maintaining shelters at least once every 40 days limited sediment blockage, and building ~ 40 kg shelters with 3-4 cm thick walls and recessed lids improved their stability during flood events. Additionally, we found that hellbenders most frequently occupied and nested in artificial shelters when they were deployed in deeper (~50+ cm) portions of reaches with high adult hellbender densities. Our results suggest that artificial shelters are effective tools for studying hellbenders when designed optimally, maintained frequently enough, and placed in appropriate locations. However, exceptions to these findings may exist in certain heavily degraded stream reaches.

Diversos aspectos metabólicos e comportamentais possuem uma estreita relação com as condições do ambiente, havendo um compromisso entre as condições naturais e a dinâmica de modificações sobre os organismos. Devido ao grande índice de degradação ambiental proveniente da atividade humana nos últimos tempos, populações de anfíbios têm sido particularmente mais afetadas devido a sua alta sensibilidade a alterações ambientais. Em uma paisagem fragmentada, a manutenção de metapopulações viáveis é um importante fator a persistência das populações. Dentro deste contexto, este estudo propõe investigar as relações entre a fragmentação florestal e habilidade das algumas espécies de anuros para se deslocar entre os fragmentos, ou entre estes e corpos d\'água. Assim, realizamos comparações, fisiológicas e comportamentais intra e interespecífica de espécies de anuros residentes em paisagens contínuas e fragmentadas em duas localidades da Floresta Atlântica, com base em suas características morfológicas. De acordo com nossos resultados, as diferenças ambientais entre as paisagens estão relacionadas com as diferenças morfofisiológicas entre as espécies. / In the last few decades, human activity has changed environmental condition, resulting in amphibian populations decline all around the world. In this study we analyze the relationships between forest fragmentation and the ability of some frog species to move between forest fragments or between fragments and breeding sites. Our study focus relies on anuran locomotor performance and supporting physiology, and the relationship between these traits and resistance to forest fragmentation. We compare morphological, physiological and behavioral traits between populations of anurans species living in different landscapes (continuous or fragmented) of two sites in the Atlantic Forest. According to our data, differences in environmental conditions of landscape are related to morpho-physiological traits. This relationship, however, depends on the site of the Atlantic Forest and also varies between species.

Amphibians are declining worldwide in response to pressures that are too numerous, difficult and rapid to ameliorate in the wild before some taxa become extinct. Ex situ conservation, whereby animals are maintained in captivity until threats in the wild have been resolved, is the only means of saving up to five hundred amphibian species. Amongst political, financial and practical hurdles, the most fundamental problem for these programmes is lack of knowledge about how to maintain species successfully in captivity. Captive populations have failed to survive or reproduce and, furthermore, captive husbandry may produce animals unsuitable for reintroduction through intra or inter-generational changes. These problems entirely undermine initiatives and if ex situ programs are to succeed, evidence based captive husbandry is needed to support captive breeding programs. In this thesis, I quantify our ignorance of amphibian requirements in captivity. Furthermore, I present investigations into fundamental areas ofamphibian husbandry, about which we currently know very little. I investigate the relationship between amphibians and Ultraviolet B (UVB) radiation and examine the relationship between UVB provision and calcium provision and evaluate routes of dietary calcium supplementation. I also present data on the effects of enrichment and rearing environment on the growth, fitness, behaviour and dermal bacterial communities of captive amphibians. These results, from a range of areas of amphibian husbandry, together demonstrate the power of the captive environment to influence the phenotype and therefore the fitness of amphibians, even within single generations. Additionally, I provide some of the first data addressing key areas of amphibian husbandry that until now have been led mostly or entirely by anecdote and hearsay.

Diversos aspectos metabólicos e comportamentais possuem uma estreita relação com as condições do ambiente, havendo um compromisso entre as condições naturais e a dinâmica de modificações sobre os organismos. Devido ao grande índice de degradação ambiental proveniente da atividade humana nos últimos tempos, populações de anfíbios têm sido particularmente mais afetadas devido a sua alta sensibilidade a alterações ambientais. Em uma paisagem fragmentada, a manutenção de metapopulações viáveis é um importante fator a persistência das populações. Dentro deste contexto, este estudo propõe investigar as relações entre a fragmentação florestal e habilidade das algumas espécies de anuros para se deslocar entre os fragmentos, ou entre estes e corpos d\'água. Assim, realizamos comparações, fisiológicas e comportamentais intra e interespecífica de espécies de anuros residentes em paisagens contínuas e fragmentadas em duas localidades da Floresta Atlântica, com base em suas características morfológicas. De acordo com nossos resultados, as diferenças ambientais entre as paisagens estão relacionadas com as diferenças morfofisiológicas entre as espécies. / In the last few decades, human activity has changed environmental condition, resulting in amphibian populations decline all around the world. In this study we analyze the relationships between forest fragmentation and the ability of some frog species to move between forest fragments or between fragments and breeding sites. Our study focus relies on anuran locomotor performance and supporting physiology, and the relationship between these traits and resistance to forest fragmentation. We compare morphological, physiological and behavioral traits between populations of anurans species living in different landscapes (continuous or fragmented) of two sites in the Atlantic Forest. According to our data, differences in environmental conditions of landscape are related to morpho-physiological traits. This relationship, however, depends on the site of the Atlantic Forest and also varies between species.

Riparian deforestation is a significant threat to freshwater riverine ecosystems and sensitive fauna that depend on clean water. Sensitive aquatic species are vulnerable to the destruction of riparian forest cover which diminishes protection from pollutants, sedimentation, and solar radiation, while also depleting dissolved oxygen. In this thesis, I explore the influence of degraded riparian forest cover and its effect on dissolved oxygen on the embryonic viability of a sensitive freshwater habitat specialist, the Eastern hellbender. Hellbenders are a large-bodied, long-lived amphibian that inhabits fast flowing, cold mountain streams in the eastern United States. Over the last several decades, hellbender populations have experienced declines that are associated with low riparian forest cover, a geriatric population age structure, and high rates of nest failure. Adult male hellbenders normally provide extensive paternal care to embryos and larvae over an 8-month period. However, researchers have recently discovered that in degraded populations, hellbender nests are failing due to whole-clutch filial cannibalism by adult males. The underlying mechanism that triggers males to eat their young remains unknown, but one possibility is that eggs are not developing properly and as a result the attending male ceases to provide care. However, the embryonic viability of clutches developing in habitats with low riparian forest cover is unknown. Given the limited research on hellbender embryonic viability, I first sought to examine whether embryo viability is associated with a forest cover gradient. To accomplish this, I inherited two years of laboratory and field data, and I conducted a final third year of data collection for the study. Over these three years of data collection, I simultaneously evaluated embryo viability in a controlled captive rearing system while classifying nest failure due to whole-clutch cannibalism of sibling embryos in the field. I found significantly lower hellbender embryo viability, faster hatching times, and higher rates of underdeveloped hatchlings in hellbender populations with degraded riparian forest cover. However, I found no relationship between embryonic viability and whole-clutch filial cannibalism. I concluded that elevated specific conductance of water (i.e., dissolved ions) associated with loss of forest cover may affect the embryonic development of hellbenders, but this hypothesis has yet to be tested. To further explore the impact of degraded riparian forest cover on hellbender embryonic viability, I designed a study to evaluate the influence of depleted dissolved oxygen on embryonic development. To accomplish this, I designed and implemented a dissolved oxygen manipulation system to rear sibling embryos in high, medium, and low dissolved oxygen concentrations. I found that hellbender embryos are vulnerable to relatively modest reductions in dissolved oxygen (i.e., 5 mg/L), comparable to those found to affect embryos of some of the most sensitive species examined to date. Nests reared in low dissolved oxygen had a lower percentage of viable hatchlings, lower hatching success, higher rates of underdeveloped hatchlings, and smaller morphometrics compared to those reared at higher dissolved oxygen concentrations. I concluded that hellbenders may be particularly susceptible to reductions in dissolved oxygen because of their high degree of specialization for well oxygenated streams, and I suggest prioritizing additional research on dissolved oxygen to advance hellbender conservation. Taken together, my research established a foundation of knowledge on the sensitivities of hellbender embryos to degraded water quality caused by low riparian forest cover. Further, my work underscored the importance of riparian forest conservation for hellbender populations and for other freshwater biodiversity. Protection of riparian forest will also be critical to build resilience in streams against the existential threat of climate change. / Master of Science / Deforestation along rivers is a significant threat to freshwater systems and sensitive animals that depend on clean water. Sensitive river species are vulnerable to the destruction of forest cover which removes protection from pollutants, run off, sun light, and exposes them to low dissolved oxygen—the amount of oxygen in the water, which is necessary for the survival of aquatic animals. In this thesis, I explore how low forest cover may impact egg quality of a sensitive freshwater animal, the eastern hellbender salamander. Hellbenders are a large-bodied, long-lived amphibian that lives in fast-moving, cold mountain streams in the eastern United States. Over the last several decades, hellbender numbers have rapidly declined. These declines are associated with low forest cover along streams, elderly populations, and unsuccessful nests. Adult male hellbenders normally provide care to their eggs and hatchlings for about eight months after the eggs are laid. Researchers have recently found that in streams where hellbender numbers are declining, hellbender nests are not successful because adult males are eating their eggs before the eggs can hatch. Researchers know that low forest cover triggers hellbender fathers to cannibalize their eggs, but the mechanism by which forest cover causes this trigger is unknown. Unsuccessful nests due to cannibalistic fathers in declining populations suggest that hellbender eggs might be unhealthy, making it more profitable to eat them than to care for them. However, the health of eggs in water from low forest cover is unknown and an important knowledge gap to fill to uncover what is triggering cannibalism in low forest cover populations. Given the limited research on hellbender egg health, I first sought to examine whether egg health is associated with changes in forest cover. To do this, I received two years of laboratory and field data, and I conducted a final third year of data collection for the project. Over these three years of data collection, I determined egg health by raising eggs in their own site water in the lab and simultaneously determined whether siblings in the field were eaten by their dads. I found lower hellbender egg health, shorter time to hatch, and more premature hatchlings in hellbender populations with low forest cover. However, I found no relationship between egg health and whether hellbender dads ate their eggs. I concluded that poor water quality associated with loss of forest cover may affect the health of hellbender eggs, but this has not been tested yet. To further explore the impact of low forest cover on hellbender egg health, I designed a study to determine the influence of low dissolved oxygen on egg health and growth. To do this, I designed and implemented a dissolved oxygen experiment to raise sibling eggs in high, medium, and low dissolved oxygen levels. I found that hellbender eggs are vulnerable to relatively moderate levels of reduced oxygen (i.e., 5 mg/l), which is comparable to how other highly sensitive species react. Nests raised in low dissolved oxygen had a lower number of healthy hatchlings, lower number of eggs that hatched, higher numbers of premature hatchlings, and smaller sizes compared to those raised in higher dissolved oxygen levels. I concluded that hellbenders may be particularly vulnerable to low dissolved oxygen because they have adapted to live in well oxygenated streams, and I emphasize the importance of studying dissolved oxygen to inform hellbender conservation. Taken together, my research created a foundation of knowledge on the vulnerabilities of hellbender eggs to poor water quality because of low forest cover. Filling these knowledge gaps is important, because it informs policy makers and managers on how to best protect hellbenders and other stream animals from declining. Further, my work emphasized the importance of forest conservation for hellbenders and for other sensitive freshwater animals. Forested streams will also be important to build protection against other human disturbances, such as climate change.

We tested the adequacy of standard 30 m riparian buffers for semi-aquatic vertebrate species, using the boreal toad (Bufo boreas boreas) as an example. We monitored toad populations in south-central Utah using radio telemetry during the summers of 2003 and 2004. We found 30 m buffers inadequate for protecting boreal toads and suggest this is likely true for other species as well. Managers must consider several factors when constructing buffers: (1) Buffer requirements may vary by time of year. While we located toads most often in wet habitats, toads commonly utilized upland habitats in late summer, occasionally at distances greater than 100 m from water. (2) A single year's observation may not be sufficient to establish adequate buffers. Toads moved into upland habitats more often and at greater distances from water (> or = 30 m) during the wetter, cooler weather conditions of 2004 than in 2003. (3) Buffer requirements may differ by sex. Male toads appeared to have stronger selection for wetland habitats than females. Females moved greater distances from water than males, often outside of buffer areas. (4) Buffer requirements may differ by location. 30 m buffers contained 82.4% of all observations, though results varied between 50.0 and 97.2%, depending on breeding location. Finally (5) All habitat requirements should be considered when establishing buffers. Many small, unmapped streams and seeps utilized by toads for hibernation were located outside buffer zones. After ground truthing and extending 30 m buffers around these habitats, the percentage of all observations within 30 m buffers increased to 92.4%. Managers need to be aware of the accuracy of digital and other mapping sources used in creating buffers and to incorporated all critical habitats in conservation buffers. Our boreal toad example suggests that ground truthing may be the most important factor in establishing effective buffer zones.

No description available.

The conservation of aquatic-breeding amphibian populations and their habitats is increasingly challenged by urban and rural development, which is occurring more intensively and more rapidly than ever before. Some species are now impacted by development throughout their range. This has forced a re-evaluation of the potential of developed landscapes for providing habitat and contributing to regional conservation strategies. For many amphibians, little is known about the criteria necessary for persistence in a developed landscape. Considerable variation in the physiology, habitat requirements, and movement behaviour of amphibians suggests that responses to habitat loss, alteration, and fragmentation are species-specific. In this thesis, I investigate species-habitat relationships for the northern red-legged frog (Rana aurora) and the Pacific chorus frog (Pseudacris regilla) in a mixed urban-rural landscape in southwestern British Columbia to evaluate the potential for species persistence despite urban and rural development throughout their range. I used repeat auditory surveys of the species’ breeding chorus to determine presence or absence at potential breeding wetlands. I then related species occurrence and abundance to characteristics of the aquatic and terrestrial environment measured at multiple spatial scales. Both species were found to use rural and urban wetlands, though R. aurora were rarely detected while P. regilla were common. Occurrence was best explained by characteristics of the terrestrial environment, rather than within-wetland characteristics, though influential terrestrial characteristics and their scale of impact differed between species. Within the context of the developed landscape, I identify species-specific positive and negative habitat associations and suggest the spatial scales at which management of these habitat characteristics will be most effective. These criteria may help to explain the species’ current distribution, prioritize management strategies, predict the effectiveness of habitat conservation and restoration projects, and inform development in municipalities seeking to maintain or enhance amphibian diversity. / Graduate / 2019-09-11

Amphibian populations are declining globally due to a litany of factors including pollution, disease, climate change, and most importantly, habitat destruction. As most amphibian life histories involve their populations being recruitment limited, focusing on the mechanism behind breeding habitat selection will reveal useful cues that managers may use to increase abundance and breeding success. Though there are many theoretical models that describe the distribution of animals in response to a resource, the ideal free distribution (IFD) theory has not yet been applied to amphibian settling decisions. Through this application of the IFD, I have found that a population of wood frogs (Lithobates sylvaticus) in Patuxent National Wildlife Refuge select vernal pools that are large, deep, and hold water into the summer months to breed from 2010-2015. This information will provide managers with the ability to predict sites where wood frogs will breed in the future, as well as describe the cues that wood frogs are cueing in on so we can protect, alter, or create ideal breeding habitat.

No description available.