<p dir="ltr">Physical traits and the hydrologic setting of lake and wetland environments strongly affect the biogeochemical signature of aquatic ecosystems and their structure and function in the landscape. Natural freshwater ecosystems have a high propensity for carbon capture and storage through aerobic production, sedimentation, and sequestration, yet differing physical characteristics including water depth, lake surface area, and watershed size likely influence the extent to which these processes occur. Anthropogenically modified ecosystems also demonstrate complex function regarding carbon cycles, where the influence of human disturbance heightens nutrients and carbon loads into aquatic systems and leads to unique biochemical regimes. Across Indiana, agricultural practices currently affect around 65 percent of the state’s landscape, while urban development and population growth are expected to expand throughout the state. This trend is modeled throughout the midwestern United States, where the impacts of urban development on aquatic environments is further heightened by expected changes in climate, as storm intensity strengthens, and rainfall increases during certain times of the year. While understudied, there is good reason to believe that Indiana’s lakes and wetlands have incredible variability in carbon processing and carbon quality within and between systems. This variation is influenced by the wide variety of drivers including hydrology, geomorphology, water chemistry, metabolic processes, and redox conditions. The interactive influence of each of these drivers, however, is poorly understood across wide scale gradients. Predicting ecosystem productivity and its relationship with carbon dynamics is therefore an important tool for understanding freshwater ecosystems’ contributions to global fluxes of carbon. The variability within and across midwestern ecosystems creates a challenging, yet critical paradigm to understand the complexities of carbon dynamics in aquatic ecosystems, emphasizing the importance for direct data collection across a stratified gradient of ecosystems. This research shows that 1) human-assigned classifications of system type, including lake, reservoir, and wetland, are useful tools in classifying the metabolic and nutrient regimes of lentic systems, and 2) morphological features including lake depth and watershed area influence the structure of carbon quality throughout the water column. Findings provide valuable information to watershed and lake managers on the importance of different physical drivers in determining water quality across a range of lentic systems.</p>

Long-Term Socio-Ecological Research (LTSER) is an inter- and transdisciplinary research field addressing socio-ecological change over time at various spatial and temporal scales. In the Austrian Eisenwurzen region, an LTSER platform was founded in 2004. It has fostered and documented research projects aiming at advancing LTSER scientifically and at providing regional stakeholders with relevant information for sustainable regional development. Since its establishment, a broad range of research activities has been pursued in the region, integrating information from long-term ecological monitoring sites with approaches from social sciences and the humanities, and in cooperation with regional stakeholders. Based on the experiences gained in the Eisenwurzen LTSER platform, this article presents current activities in the heterogeneous field of LTSER, identifying specific (inter-)disciplinary contributions of three research strands of LTSER: long-term ecological research, socio-ecological basic research, and transdisciplinary research. Given the broad array of diverse contributions to LTSER, we argue that the platform has become a relevant "boundary organization", linking research to its regional non-academic context, and ensuring interdisciplinary exchange among the variety of disciplines. We consider the diversity of LTSER approaches an important resource for future research. Major success criteria of LTSER face specific challenges: (1) existing loose, yet stable networks need to be maintained and extended; (2) continuous generation of and access to relevant data needs to be secured and more data need to be included; and (3) consecutive research projects that have allowed for capacity building in the past may be threatened in the future if national Austrian research funders cease to provide resources.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 2016. / Stable isotope analyses have been used to infer diets of organisms, define trophic partitioning, and infer geographic origins of species. It has further been applied to forensic ecology to infer the origins of deceased humans and illegally traded animal (elephant ivory and rhinoceros horn) and plant (cycads, coca, and cannabis) material. However, no research has focused on the isotope analysis of avian material in forensic ecology. African grey parrots Psittacus erithacus are one of the most traded species in the world, with the trade often being illegal, and the origins of confiscated or deceased specimens being unknown. The aim of this study was to determine if stable isotopes (δ 13C, δ 15N, and δ 2H) in African grey parrot feathers could be used to determine the wild or captive origins of birds. African grey parrot feathers (primary, body, and tail) differed isotopically so standardising isotope values of African grey parrot feathers to a single feather type was recommended, to maintain consistent sampling and allow for comparisons to be drawn between different feather types. African grey parrot feathers from unknown origins can be identified as wild or captive using δ 13C and δ 2H values, but not δ 15N values. Known wild and captive feathers possibly differ isotopically from one another because of dietary and location differences. Wild African grey parrots inhabit and feed in isotopically depleted C3 forests compared to captive African grey parrots which are usually fed C4 based foods with more positive isotope values. Wild African grey parrot δ 2H isotope values were the most negative in the central region of their native distribution. The ability to differentiate wild from captive African grey parrots, as well as infer basic origins (East from West Africa) may improve the monitoring of the illegal trade as well as help in tracing illegally traded parrots. / LG2017

Thesis (MTech (Nature Conservation))--Cape Peninsula University of Technology, 2017. / Stable isotope analysis (SIA) of whiskers has been used to identify temporal feeding habits, intra-population diet variation, as well as individual dietary specialisation of marine and terrestrial carnivores. However, the potential of the method to disclose such dietary information for large wild felids has been little explored. The accurate interpretation of stable isotope ratios along serially sampled whiskers is hampered by lack of information on species-specific whisker growth rates, whisker growth patterns and whisker-diet trophic discrimination factors (TDFs). Whisker growth rate and growth pattern informs on the time period encapsulated in the analysed segment of a whisker, while whisker-diet TDFs are required to make correct deductions of the prey species consumed by a predator. The aim of this study was to develop and evaluate the technique of using stable carbon and nitrogen isotope analysis of felid whiskers to quantify the diet of wild felids and in particular, to identify diet variation among individuals. To achieve this, lion Panthera leo and leopard Panthera pardus whisker growth rate and growth pattern, and lion whisker-diet TDFs were measured, using captive individuals held at the National Zoological Gardens, Pretoria. The viability and applicability of the technique was then explored on six free-ranging leopards in Phinda Private Game Reserve (hereafter Phinda), northern KwaZulu-Natal (KZN) whose diets have been intensively studied using traditional methods. Whisker growth rates and growth patterns were measured for four lions (three sub-adult females and one adult male) and an adult male leopard over 185 days using giraffe Giraffa camelopardalis meat as an endogenous biomarker to consecutively mark whiskers as they grew. The 13C-depleted, C3-derived giraffe meat with its characteristic isotopic signature could be discerned from the 13C-enriched diet of C4 grain-fed beef and chicken the felids were sustained on. Two whiskers were removed from each felid at the beginning of the experiment, and felids were fed the giraffe meat at four predetermined periods to mark the whiskers replacing the removed ones. The periods with low δ13C values, identified following serial sectioning of the regrown whiskers at 1 mm intervals (and stable isotope analysis of these sections), were then correlated to specific giraffe meat feeding bouts and hence growth periods. Knowledge of the duration between giraffe meat feeding bouts enabled the calculation of whisker growth rate and determination of growth pattern. δ13C and δ15N whisker-diet TDFs were estimated for five lions whose diet remained consistent over multiple years. Whiskers removed from four lions at the beginning of the whisker growth experiment, a whisker removed from a female lion as part of a pilot study a year before the experiment and the diet (chicken and beef) samples collected during the experiment were analysed for their isotopic ratios. These were used to calculate isotopic differences between lion whiskers and diet.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references (leaves 118-121).

Thesis (Ph.D.)--University of Central Florida, 2008. / Adviser: Graham A. J. Worthy. Includes bibliographical references.

Stable isotope analyses are powerful tools for reconstructing ancient ecologies and ecosystems, as they are independent of morphology and directly reflect dietary ecology. The application of stable isotope analyses, however, is not without limitations, as determination of food web dynamics using these methods often relies on poorly tested assumptions. The guiding thread of this thesis is the testing of foundational cornerstones on which these methods rely, in order to validate the suitability of applying these techniques to different mammalian clades, and to more reliably and confidently interpret the isotopic signals preserved in extinct organisms. The first chapter of this thesis tests the validity of an important assumption behind the interpretation of stable carbon isotope analyses for understanding diet in terrestrial mammalian herbivores: if, as assumed for almost two decades, mammalian bioapatite δ¹³C is enriched by 14‰ relative to dietary δ¹³C. By analyzing new isotopic data from a never before assessed herbivorous group spanning a broad range of body masses—sloths (Xenarthra, Mammalia)— and other mammals with experimentally controlled or observationally known diets, I discovered considerable variation in diet–bioapatite δ¹³C enrichment among mammals. Statistical tests (ordinary least squares, quantile, robust regressions, Akaike information criterion model tests) documented independence from phylogeny, and a previously unrecognized strong and significant correlation of δ¹³C enrichment with body mass for all mammalian herbivores. A single-factor body mass model outperformed all other single-factor or more complex combinatorial models evaluated, including for physiological variables (metabolic rate and body temperature proxies), and indicated that body mass alone predicts δ¹³C enrichment. These analyses, spanning more than 5 orders of magnitude of body sizes, yield a size-dependent prediction of isotopic enrichment across Mammalia and for distinct digestive physiologies, permitting reconstruction of foregut versus hindgut fermentation physiologies for fossils and refined mean annual paleoprecipitation estimates based on δ¹³C of mammalian bioapatite. Second, I sought to evaluate the existing paradigm governing identification of closed canopy rainforests in the fossil record using mammalian δ¹³C data: the presence of mammals with dietary δ¹³C <-31‰, which has only been observed in closed canopy rainforests in Equatorial Africa, the only other tropical ecosystem sampled extensively. This chapter provides a characterization of δ¹³Cbioapatite, δ¹³Chair and δ¹⁵Nhair of a modern mammalian community in western Amazonia, in Peru, to test if the isotopic structure of mammals in this Neotropical ecosystem is similar to those in African tropical rainforests. The results indicate that despite their marked geographical and taxonomic differences, median δ¹³Cdiet values from closed canopy rainforests in Amazonia (-27.4‰) and equatorial Africa (-26.9‰) are not significantly different. Amazonian mammals, however, seem to exploit a narrower spectrum of dietary resources than equatorial African mammals, as depicted by the absence of highly negative δ¹³Cdiet values previously proposed as indicative of rainforests (<-31‰). I hypothesize that differential effects of late Pleistocene extinction may be responsible for the ecological disparities among the two rainforests, by significantly reducing evolutionary time and dietary breadth reflected in the modern Amazonian mammalian community. Finally, the third chapter of this dissertation evaluates assumptions behind δ¹⁵N amino acid compound specific analyses in order to test the controversial hypothesis of carnivory and consumption of proteins of animal origin in fossil sloths. This analytical technique relies on three main assumptions. First, that the offset between the δ¹⁵N of glutamic acid (δ¹⁵NGlx) and phenylalanine (d15NPhe) in the organism under study will increase with increasing trophic level. Second, that the offset between δ¹⁵NGlx and δ¹⁵NPhe at the base of the food chain is relatively constant and has a value of -8.4‰ for C3 ecosystems. Third, that the trophic discrimination factor in all ecosystems (the difference in δ¹⁵NGlx relative to δ¹⁵NPhe with increasing trophic level) is 7.6‰. The results of my experiments conducted on extant xenarthrans (sloths and anteaters) with controlled diets document that only the first assumption holds true. Rather than relying on an equation with constants introducing uncertainties and that are not applicable to organisms feeding on a combination of items of different origin (e.g., C3 + C4 plants), δ¹⁵NGlx and δ¹⁵NPhe values by themselves can accurately reconstruct the trophic position of organisms. Indeed, the results on δ¹⁵NGlx and δ¹⁵NPhe herein obtained for five xenarthran species in controlled feeding experiments, combined with mammalian data available from the literature, show strong and significant correlations between these two AAs and with trophic positions. Both the TP equation and the regression analyses of δ¹⁵NGlx and δ¹⁵NPhe suggest that the Pleistocene fossil ground sloths 𝘔𝘺𝘭𝘰𝘥𝘰𝘯 𝘥𝘢𝘳𝘸𝘪𝘯𝘪𝘪 and 𝘕𝘰𝘵𝘩𝘳𝘰𝘵𝘩𝘦𝘳𝘪𝘰𝘱𝘴 𝘴𝘩𝘢𝘴𝘵𝘦𝘯𝘴𝘪𝘴 were not pure herbivores as commonly presumed, but rather that they were both mixed feeders/omnivores, incorporating items of animal origin in their diets.

No description available.

Thesis (Ph.D. (Zoology & Entomology)) - Rhodes University, 2008.

Thesis (M.S.)--Marshall University, 2002. / Title from document title page. Document formatted into pages; contains vi, 62 p. illustrated with photos and maps. Includes bibliographical references (p. 26-31).