Download or read book Using Ecological Stoichiometry to Explain the Effects of Spatial Subsidies on Larval Amphibian Development and Disease written by and published by . This book was released on 2015 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cross-ecosystem transfer of matter is vital to the productivity of many ecosystems. Most prior studies have focuses on the total energy (biomass) of these spatial subsidies, but the quality (i.e., nutritional content) of subsidies can be equally important. Ecological Stoichiometry (ES) provides a theoretical framework to predict effects of subsidy quality, based on the elemental composition of the subsidy itself relative to the composition of the recipient system. In this dissertation I use ES theory to predict effects of a spatial subsidy (leaf litter) on the performance of a secondary aquatic consumer (wood frog Lithobates sylvaticus tadpoles). First, I show that ES can predict a priori the growth rates of wood frog tadpoles feeding on a leaf litter quality (nitrogen) gradient. Second, I show that the fitness benefits of maternal provisioning, a life history strategy to improve offspring competitive performance, are greater when leaf litter quality (nitrogen) is low. Third, I show that tadpole resource limitation changes as a function of ontogeny, due to shifts in tissue stoichiometry during periods of bone ossification. Finally, I show that rates of parasitism can increase in tadpoles when resource quality is low, mediated by bottom-up and top-down effects on exposure and susceptibility. Taken together, the results of this dissertation highlight the relevance of ES theory to spatial subsidy theory and to anuran biology in general.
Download or read book Effects of Spatial Subsidies and Canopy Cover on Pond Communities and Multiple Life Stages in Amphibians written by Julia E. Earl and published by . This book was released on 2012 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spatial subsidies are resources that move from one ecosystem to another. In aquatic systems, canopy cover determines both light availability and subsidy input in the form of senescing leaves. This phenomenon has been well studied in streams, and general patterns of ecosystem production, community structure, and the reciprocal export of animals have been discovered. I was interested in whether these patterns also occurred in ponds. I examined these patterns using experimental pond mesocosms and supported the results using an observational study of natural ponds. For the pond mesocosm experiment, I placed mesocosms along a canopy cover gradient and manipulated spatial subsidy input. I found a shift from net heterotrophy in closed canopy mesocosms to a balance between heterotrophy and autotrophy in open canopy mesocosms. The macroinvertebrate community structure responded to both canopy cover and subsidy input in mesocosms. The biomass of collectors (detritivores) was highest in mesocosms with litter input and increased with canopy cover, a pattern also present in natural ponds. Finally, I found that litter input increased the reciprocal export of amphibian biomass compared to no input. Amphibian biomass also decreased with increases in primary productivity. This research highlights the importance of spatial subsidies that connect different ecosystem types. Conserving these ecosystem connections will help maintain biodiversity and ecosystem function.
Download or read book Ecological Effects of Climate Change on Amphibians written by Hilary Byrne Rollins and published by . This book was released on 2019 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: With climate change, global average temperatures are increasing and becoming more variable. As a result, reproductive phenology is shifting earlier, body size is decreasing in ectotherms, and snow cover is decreasing. I examined how these effects of climate change affected amphibians and their ecological interactions across life stages. In Chapter 1, I investigated whether an early shift in phenology could alter subsequent life history events, if the organisms were able to compensate, and if compensation was costly. Despite a seven day difference in hatch date, frogs from the delayed egg phenology treatment accelerated growth and development to metamorphose at the same time as the early egg phenology treatment. Frogs that accelerated development metamorphosed at the same size as frogs that did not accelerate development but had the same food availability, indicating that there was no size cost of compensation. In Chapter 2, to understand how climate change-induced shifts in phenotype could affect important interspecific interactions, I examined how a shift in wood frog larval phenology, and body size altered post-metamorphic competition with American toads. The interaction of wood frog metamorphic size and phenology affected toad body condition such that wood frogs that metamorphosed earlier and smaller, as expected under climate change, led to toads with higher body condition.Finally, in Chapter 3, I tested whether the effects of climate change on wood frogs were altered by early ecological interactions. I examined how predation during larval development affected how wood frogs would tolerate a reduced snow cover winter. Exposure to predators during larval development increased mass at metamorphosis, time to metamorphosis, and larval growth rate. Snow removal increased frog mortality. The interaction of larval exposure to predators and reduced snow cover caused a steeper relationship between mass and body length in animals that experienced both. I found that the ecological effects of climate change shifted larval development and juvenile growth, reduced the ability to compete against interspecific competitors, increased winter mortality, and altered spring body condition. These effects may scale up to affect population dynamics and fitness, and demonstrate the importance of considering ecological effects of climate change.
Download or read book Ecotoxicology of Amphibians and Reptiles written by Donald W. Sparling and published by CRC Press. This book was released on 2010-06-02 with total page 946 pages. Available in PDF, EPUB and Kindle. Book excerpt: Building on the success of its popular predecessor, the second edition of Ecotoxicology of Amphibians and Reptiles presents newly available findings on the species that are important environmental indicators. This new edition covers nearly twice as many topics as the first, including recent developments in the ecotoxicology of amphibians and reptil
Download or read book The Effects of Mineral Nitrogen on Embryonic and Larval Amphibians written by Kerry L. Griffis-Kyle and published by . This book was released on 2005 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: Overall, my research demonstrates that mineral N can increase amphibian mortality and slow growth and development in embryonic and larval stages and is important to consider when managing amphibian populations, especially in amphibians that breed in ephemeral pools where mineral N concentrations can be elevated into the summer and delays in development can lead to catastrophic failures in reproduction.
Download or read book Ecological and Physiological Effects of Environmental Stressors Across Life stages in Amphibians written by Kacey Lynn Dananay and published by . This book was released on 2018 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the effects of environmental stressors includes identifying how stressors affect individual physiology and ecological communities. Considering carry-over effects, effects from one life-stage persisting into later life-stages, can further reduce the chances of under- or over-estimating the effects of environmental stressors. I investigated the effects of two environmental stressors on amphibian physiology across life-stages including direct and indirect effects. I first investigated road salt. Road salt, a de-icing agent used on highways, can spread up to 1km in wetlands during snowmelt. It may be particularly important for early breeding amphibians like wood frogs (Rana sylvatica). Road salt significantly increased larval frog growth and algal biomass which was likely due to an indirect effect of salt decreasing zooplankton abundance, an algal competitor of frogs. A second experiment found despite increased larval growth, exposure to road salt caused juvenile frogs to have higher mortality in low-density terrestrial environments. The second stressor I investigated was Artificial Light At Night (ALAN). ALAN reduced metamorphic duration of American toads (Anaxyrus americanus) and periphyton biomass but did not affect the colonization of toad predators. These results suggested the effects of ALAN are mediated through direct rather than indirect effects. Extending this experiment found juvenile growth was reduced by juvenile-stage exposure to ALAN. Increased juvenile activity, specifically the lack of suppressed nocturnal activity, likely reduced juvenile growth of individuals housed with ALAN. Furthermore, carry-over effects were also present; larval-stage ALAN marginally increased juvenile activity. In the final experiment, I added an additional stressor: predation. Predators reduced toad survival and mass, regardless of ALAN. This suggests ALAN did not increase predator consumption of toads. Neither predators nor ALAN affected corticosterone production in the tadpole or metamorph life-stages but larval-stage ALAN increased corticosterone production in juvenile toads. These experiments demonstrated environmental stressors can have direct and indirect effects. Furthermore, larval stage stressors can carry-over and affect later life-stages even if that stressor is no longer present. Future environmental stressor studies should investigate direct and indirect effects together and extend experiments beyond a single life-stage. As demonstrated here, failure to do so may under-estimated the effects of these environmental stressors.
Download or read book The Effect of Ontogeny on Interspecific Interactions in Larval Amphibians written by Michael J. Sredl and published by . This book was released on 1991 with total page 2239 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of an Insecticide on Amphibian Communities written by Michelle Dawn Boone and published by . This book was released on 2000 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rachel Carson's Silent Spring raised public awareness that there were ecological consequences to widespread pesticide use. Yet many of the pesticides used today are benign in comparison with the early synthetic pesticides. However, the effects of these chemicals are typically not tested on living communities. The effects of pesticides on natural community dynamics may be especially noteworthy for amphibians in light of recent concerns about amphibian declines. The main objective of my research was to determine how realistic, sublethal levels of the short-lived insecticide carbaryl may influence amphibian species that are experiencing stresses known to be important in the natural environment (e.g., competition, predation, pond drying). This research was conducted in artificial ponds (i.e., cattle tanks) and in small farm ponds to test the effects of carbaryl on amphibians. Carbaryl may serve as a model chemical for other contaminants with the same mode of action (acetyl cholinesterase inhibition: carbamates and organophosphates). I measured endpoints at metamorphosis (survival, mass, and age) to determine if exposure to carbaryl had lasting effects on tadpole development and survival. Studies in cattle tank indicated that the effects of carbaryl varied depending on the predator environment and initial larval density for some species. Interactions of carbaryl with predator and density may result in an indirect effect of carbaryl causing increased food resources through the elimination of zooplankton populations that may compete for similar resources as tadpoles; this resulted in greater survival and greater mass at metamorphosis for some species relative to individuals in control ponds. In an experiment where multiple exposures to carbaryl were applied, exposure led to higher rates of metamorphosis with the majority of metamorphs coming from high-density ponds dosed three times. This interaction suggests that exposure to carbaryl later in the larval period may have stimulated metamorphosis in high-density conditions. Because natural environments include a large range of factors typically excluded in experimental studies, we cannot assume contaminant levels that are safe in the laboratory or in mesocosms are protective of populations in the natural environment. A study in farm ponds, however, suggested that even a short-lived contaminant like carbaryl can affect amphibian species in field conditions. Carbaryl exposure positively influenced survival with approximately twice as many individuals leaving carbaryl treated ponds than control ponds. Our results indicate that differences in biotic conditions influenced the potency of carbaryl and that even low concentrations induce changes that may alter community dynamics in ways not predicted from single-factor, laboratory-based studies. Additionally, our results suggest that even in realistic conditions where predatory and competitive conditions may be strong, contaminants can still alter population dynamics.
Download or read book Effect of Agricultural Pesticides and Land Use Intensification on Amphibian Larval Development written by Claudia Patricia Camacho Rozo and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increase in human population had to increase the demand for vital resources, including food, generating intensive and extractive exploitation, and impacting natural ecosystems and biodiversity. Land degradation of ecosystems is a serious and widespread problem in the world. The expansion of the agricultural frontier is by direct or indirect human-induced processes, expressed as long-term reduction or loss of biodiversity. The expansion and industrialization of agriculture had been negatively affected by soil fertility, the climate, biogeochemical cycles, bodies of water, and loss of biodiversity on different spatiotemporal scales. Intensive agriculture, in the form of monocultures, is subjected to strict pest controls for the use of highly toxic agrochemicals. Pesticides are used in monocultures by spraying aqueous dilutions. Knowing the toxic effect of pesticides and agrochemicals on amphibians is very important. These animals have special ecophysiological conditions because they have biphasic life cycles composed of an embryonic and larval aquatic development stage and the adult stage in humid terrestrial environments. For these reasons, the amphibians have been observed with increased mortality rates, reduced prey availability, and affected growth rates.
Download or read book Dietary Effects on the Stoichiometry of Growth Regulation and Wastes of Ozark Stream Insect Detritivores written by Halvor Matthew Halvorson and published by . This book was released on 2016 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: A widespread stressor, anthropogenic nitrogen (N) and phosphorus (P) pollution can increase resource nutrient content and alter animal community composition in freshwater ecosystems. In this dissertation, I used ecological stoichiometry theory to examine effects of diet nutrient content and leaf litter type on growth, regulation, and wastes of aquatic invertebrate detritivores. I tested effects of leaf litter diet carbon:phosphorus (C:P) on growth and stoichiometric regulation of the detritivorous caddisfly Pycnopsyche lepida and used results to determine a threshold elemental ratio of oak litter C:P=1620 that confers peak growth of this species. This empirical, growth-based approach provided a more accurate estimate of the threshold elemental ratio compared to current bioenergetics models. Subsequent experiments used 33P and 14C as microbial tracers to examine effects of diet leaf type and nutrient content, as well as taxonomic identity, on incorporation efficiency of microbial C and P by the detritivorous caddisflies Pycnopsyche lepida, Lepidostoma sp., and Ironoquia sp. Results showed no effects of leaf type on incorporation efficiencies, however elevated litter P content reduced caddisfly incorporation efficiency of microbial P, and there were inverse relationships between caddisfly body C:P content and incorporation efficiencies of microbial C and P, suggesting stoichiometric links of detritivore growth rates and P requirements to reliance on litter microbial nutrients. Given the stoichiometry of growth and regulation can vary across diets and taxa to affect production and composition of animal wastes, I also examined effects of litter type and nutrient content on the stoichiometry of particulate wastes from the detritivores Pycnopsyche lepida, Lepidostoma sp., and Tipula abdominalis. Higher litter N and P content increased N and P content of particulate wastes, but the strength of effects often differed between maple and oak litter and Tipula abdominalis produced N- and P-deplete wastes compared to Pycnopsyche lepida and Lepidostoma, indicating potential taxonomically variable effects of animals on the stoichiometry of fine particulates in streams. Finally, I conducted a long-term study of C, N, and P dynamics of decomposing egesta from the detritivorous taxa Tipula sp., Lirceus sp., and Allocapnia sp. fed low- or high-P litter. Egesta from Allocapnia and Tipula decomposed faster than egesta from Lirceus, and elevated P content of egesta increased total uptake of dissolved N by egesta during decomposition. Together, my findings provide evidence that, by increasing litter nutrient content, anthropogenic nutrient pollution alters multiple species-specific functional roles of detritivorous animals in aquatic ecosystems.
Download or read book Effects of Chronic Pesticide Exposure on Larval Amphibians written by Shannon E. Julian and published by . This book was released on 2000 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effects of a Chemical Stressor on Amphibian Larvae written by Christine Marie Bridges and published by . This book was released on 1999 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are an increasing number of studies are now focusing on the effects that xenobiotics have on amphibians, an interest likely stimulated by widespread reports of amphibian declines. Chemical contamination may be partially to blame for these declines, by disrupting amphibian growth, reproduction, and behavior. However, evidence that xenobiotics, are directly to blame for these population declines is sparse, because environmental xenobiotic concentrations typically are not great enough to generate direct or immediate mortality. I, therefore, examined the effects of exposure of tadpoles to sublethal levels of contaminants because they may lead to the subtle changes that are ultimately contributing to population declines. Tadpoles acutely exposed to sublethal carbaryl concentrations decreased spontaneous swimming activity and swimming performance (i.e., sprint distance). When tadpoles were chronically exposed to sublethal carbaryl levels, there was an increase in mortality as well as the incidence of deformities. Furthermore, tadpoles exposed to carbaryl as eggs were smaller at metamorphosis than their corresponding controls. Consequently, it is possible that chemicals (e.g., carbaryl) in the environment are responsible for causing some amphibian declines by altering tadpole behavior, growth, and development, which ultimately may affect population dynamics. Using two assays (one lethal, one sublethal), I observed a significant degree of variation in tolerance to carbaryl at three of the hierarchical levels I examined: among nine ranid species, among ten populations of a single species, Rana sphenocephala, and within several populations of R, sphenocephala, and among full- and half-sibling families. Although it may be predicted that species in decline are more sensitive to environmental stressors (e.g., chemicals), two of the three species that are currently in decline were the most tolerant to carbaryl. Significant variation among R. sphenocephala populations and among families within these populations suggests that caution should be taken when making inferences to other populations or families, respectively. When examining differences among paternal half-sibling families, I found no significant variation in tolerance to carbaryl, indicating that little variation is available for adaptation to environmental stressors within this population. Determining the degree of variation in responses within and among amphibian species is important to amphibian conservation, because only when variation is present will amphibians have the ability to adapt and persist in changing environments.
Download or read book Persistence of the Larval Environment on Post metamorphic Performance and Population Dynamics in Amphibians written by Julie Charbonnier and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Organisms with complex life cycles may experience diverse stressors during their development. Stressors experienced in early life stages may influence the quantity and quality of individuals in later life stages. However, it is unclear if these effects persist later in life and how they may influence population dynamics. This dissertation uses two amphibian species, the Western spadefoot toad (Pelobates cultripes) and the spotted salamander (Ambystoma maculatum) to explore how biotic and abiotic factors experienced in aquatic and terrestrial environments influence phenotype and survival. We use a combination of field mesoscosm studies, laboratory studies and modeling to explore how early life history stressors persist in diverse environmental contexts. In Chapter 1, pond drying and larval density negatively influence multiple aspects of phenotype in the Western spadefoot toad. In Chapter 2, reduced body size due to larval stressors persisted in the first year of life in spotted salamanders in both high and low terrestrial resource environments. Additionally, there was no relationship between size at metamorphosis and post-metamorphic terrestrial survival. In Chapter 3, low terrestrial moisture levels reduced post-metamorphic growth rates by reducing food intake in juvenile spotted salamanders from both high and low larval density treatments. In Chapter 4, we scale up the effects of reduced body size in the Western spadefoot toad to explore how reduced body size due to pond drying may influence population densities using a stage specific matrix model. Reduced body size, by delaying maturity, may reduce adult densities in the Western spadefoot toad. This dissertation suggests that life stages are highly interconnected, as stressors experienced early in life stage may persist through their effects on phenotype in the absence of compensatory mechanisms. Variation in later life stages may also influence phenotype, but may not completely erase effects of early environments. Stressors experienced early in life may also translate to population level consequences, especially when organisms experience multiple stressors across life stages.
Download or read book Lethal and Sublethal Effects of Nutrient Pollution on Amphibian Larvae written by Julia Elizabeth Earl and published by . This book was released on 2007 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents results of three experiments which were performed to further develop developmental stability for use in the conservation of amphibian species and to examine the toxicity of nutrients.
Download or read book The Spatial Ecology of Climate Influences Species Distributions written by Gabrielle L. Rimok and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Species distributions are largely determined by three main drivers: abiotic environmental conditions, dispersal, and biotic interactions. Because abiotic environmental conditions determine habitat suitability, they also have direct implications on the capacity of species to disperse and how species interact with one another in space. However, it is specifically the variability in abiotic environmental conditions (i.e., environmental heterogeneity) and how they are spatially structured (i.e., environmental spatial autocorrelation - ESA) that determines whether or not a habitat, or even a landscape, is environmentally suitable for species establishment. Environmental heterogeneity itself is spatially structured; where environmental conditions/features that are closer together in space tend to be more similar than those farther apart. As such, the spatial structure of environmental features (i.e., ESA) mimics dispersal networks because spatial patterns in environmental heterogeneity affect the strategies and energetic costs (and their associated fitness consequences) involved in movement and dispersal among patches. At broad spatial scales, species distributions are shaped by environmental conditions, namely, those of climate. Climatic conditions thus also impose important physiological and life history constraints on species and in accordance with environmental features, are also often heterogeneous and spatially structured. Yet, how they affect and contribute to species distributions remains unknown. Here, we use species distribution models (SDMs) in a novel framework in which we demonstrate for the first time, the influence of climate heterogeneity (within and between patches) and climate spatial structure on species distributions. We evaluated six different SDMs testing both the individual and combined effects of climate variables (i.e., between and within-patch climate heterogeneity and climate spatial structure) on species distributions, using 301 North American amphibian species as a case study. Our results demonstrate that a model using climate spatial structure as a predictor alone explained species distributions better than any other model in the majority of species. Although a model including both climate heterogeneity (within and between-patch) and climate spatial structure as predictors was only the best model for a handful of species, we provide critical evidence that there is added value in considering climate spatial structure when fitting different SDMs for the same species. Most importantly, we demonstrate that climate spatial structure and heterogeneity are important mechanisms driving species distributions in North America.
Download or read book The Culinary Herpetologist written by and published by Bibliomania. This book was released on 2005 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a compilation of nearly 1000 recipes for amphibians and reptiles. Although all of these recipes have been used by people at one time or another this book is meant primarily to document these recipes. A unique and unusual collection of culinary history.
Download or read book Trophic Ecology written by Torrance C. Hanley and published by Cambridge University Press. This book was released on 2015-05-07 with total page 427 pages. Available in PDF, EPUB and Kindle. Book excerpt: As researchers try to predict the effects of human modification at all trophic levels and mediate the impact of rapid environmental change, it has become clear it is no longer a matter of agreeing that both bottom-up and top-down forces play important roles in diverse ecosystems. Rather, the question is: how do these forces interact across aquatic and terrestrial systems? Written by leading experts in the field, this book presents a unique synthesis of trophic relationships within and across ecosystems that is a valuable foundation for the development of cross-system, multidisciplinary research. It also provides new insights into population biology and community ecology and examines the interactive effects of bottom-up and top-down forces on biodiversity at each trophic level. A one-stop resource for learning about bottom-up and top-down interactions, this book encourages discussion and collaboration among researchers to identify similarities and differences in trophic interactions across aquatic and terrestrial systems.
