Dissertations / Theses on the topic 'Stable isotope analysis (SIA)'

The deep-sea is the largest habitat on earth, containing over 90 percent of the world’s oceans and home to over 20,000 species. Deep-sea ecosystems are increasingly impacted by human activities including fishing and oil extraction. To understand potential impacts on deep-sea food webs, it is crucial to gather baseline data in these systems. I quantified the trophic interactions of three groups of deep-water animals across a range of trophic levels living in the northern and eastern Gulf of Mexico using stable isotope analysis. First, I propose methods for correcting δ15N values for the presence of nitrogenous metabolic waste products (e.g., urea) in muscle tissue using chemical extractions and/or species-specific mathematical normalizations. Significant differences in δ15N, %N, and C:N values as a result of extractions were observed in eight of ten shark and all three hagfish species. The δ15N values increased, but shifts in %N and C:N values were not unidirectional. Mathematical normalizations for δ15N values were successfully created for four shark and two hagfish species. I then describe the trophic interactions of three consumer assemblages. Carbon isotopic values indicate a heavy reliance on allochthonous nutrient inputs from surface waters. Nitrogen isotopic values reveal somewhat atypical taxa as top predators in the deep sea. Shark, teleost, and invertebrate species across a wide range of body sizes are feeding at a similar trophic level. This apparent lack of size structuring could be the result of a high degree of opportunistic scavenging or perhaps feeding at many trophic levels simultaneously in an oligotrophic system. There was a high degree of isotopic niche overlap among species within each consumer assemblage, perhaps the result of limited nutrient resources in the deep-sea. In general, individuals from the northern sampling stations displayed higher δ13C and δ15N values than those from the eastern sites. With the exception of a few species, there were no strong relationships between body size and isotopic values. The present study is among the first characterizations of the trophic structure of deep-sea organisms in the Gulf of Mexico and establishes system baselines for future studies describing deep-water systems and investigating anthropogenic impacts.

Thesis (B. Sc.(Hons.))--University of Adelaide, Dept. of Geology and Geophysics. 1992.
One folded map and one folded chart in pocket inside back cover. "National grid references Marree SH-54-5 (1:250,000) Parachilna SH-54-13 (1:250,000)." Includes bibliographical references (p. [2-7]).

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous, toxic contaminants that are released to the environment from various petrogenic and pyrogenic sources. In an effort to more clearly identify and trace sources of PAHs in the environment, purification and compound specific isotope analysis methods were developed to accurately measure the stable carbon isotope ratio of individual PAHs. Development of the method included improving accuracy and precision of the isotopic measurement by producing highly pure extracts using various chromatographic techniques. The method was refined by improving compound separations using purification techniques and high resolution chromatographic columns. The purification method consists of alumina/silica gel column chromatography, gel permeation chromatography and thin layer chromatography. The mean recovery of PAHs after the purification procedure was approximately 80 %. Sample purities after purification were verified by GC/FID and full scan mass spectrometry. To better resolve peaks and provide more accurate stable carbon isotope measurements, various gas chromatographic conditions were evaluated. The precision of the method ranged between 0.08 and 0.43 . The analytical protocols were evaluated to confirm compositional and stable isotopic integrity during purification and stable isotopic analysis. To confirm the utility of the purification and isotope analysis methods, various environmental samples from marine, land and lacustrine environments were analyzed. The isolates were analyzed for the composition and the stable carbon isotope ratios of PAHs. The stable carbon isotope ratio was measured by GC/IRMS and the results, along with quantitative compound compositions, were used to characterize and identify the contaminant sources. The sources of the PAHs in the study areas were differentiated by PAH molecular ratios and confirmed by stable carbon isotope ratios. This study confirms that compound specific isotope analysis of pollutants by GC/IRMS can be used to identify PAH sources in environmental samples. The study also confirms that the purification and stable carbon isotope analysis methods that were developed can be used to accurately measure the stable carbon isotope ratios of PAHs in environmental samples for the purpose of source identification. GC/IRMS measurement of stable isotopic compositions can be an effective fingerprinting method when used in conjunction with traditional molecular composition methods.

This thesis explores the use of carbon, nitrogen and sulphur stable isotope analysis of modern and archaeological human hair as an indicator of human diets. The thesis is focused around three distinct research projects, two on modern, living humans and one on an archaeological population. The first project focuses on dietary variation among different populations in modern Ethiopia that share the same resource base but follow different economic and subsistence patterns. This research shows that economic and cultural patterns can cause very distinct and significant differences in diet among populations with access to the same resources. The second project uses data from modern Nicaraguan villagers to explore variability in isotopic signatures among demographic groups within one population. The data reveal significant differences among demographic groups, but the absolute differences are quite small, indicating that it is necessary to have a large sample size to determine isotopic differences within a population. The third project is an archaeological case study presenting the first serial isotopic analysis of human hair from the Basketmaker II (BMII) midden at the site of Turkey Pen Ruins on Cedar Mesa, in south-eastern Utah. These data show potential seasonality of diet at the site, with variations in the amount of C₄ protein being contributed to the diet. Together these projects contribute to our understanding of how different scales of dietary variation can be interpreted and approached through isotopic analysis of human hair. The studies also show the applicability of both intra-individual and inter-individual isotopic analysis of human hair to our understanding of modern and ancient diets.
Arts, Faculty of
Anthropology, Department of
Graduate

Stable isotope analysis (SIA) is a valuable tool in ecotoxicology because δ13C and δ15N may provide insights into the trophic transfer of contaminants in a food web. The relationship between a species’ trophic position (TP, determined from δ15N) and internal concentration of biomagnifying contaminants can be established and used for regulatory purposes. However, the exposure of organisms to xenobiotics incurs physiological costs, and the stable isotope signature of a consumer reflects not only diet but also a physiological state. The latter raises questions regarding the interpretation of stable isotope signatures in contaminated areas. Therefore, the aim of this Thesis was to evaluate the behaviour of consumers’ stable isotope signatures in stressed systems, with a primary focus on the effects of environmental contaminants. In paper I, the physiological costs of chemical exposure were found to alter incorporation rates of dietary nitrogen and carbon in a consumer by influencing both growth and metabolic turnover, with resulting changes in isotope signatures relative to a control system. In paper II, the diet-consumer discrimination factors for 15N and 13C were confirmed to increase under chemical exposure mediated via increased metabolic costs. However, the physiological response was low and translated into only minor shifts in the δ13C and δ15N. The predictability of exposure effects on the stable isotope signature was demonstrated in paper III, in which animals exposed to a chemical with a known mode of action presented expected effects on elemental composition, body size, biomarkers of oxidative stress and the stable isotope signatures. Moreover, consumers’ oxidative balance was found to be related to their δ15N values, thus providing evidence of the kinetic isotope effect on the oxidative status. However, despite the alterations in stable isotope signatures observed in laboratory settings (papers I-III), the effect of xenobiotics on the TP estimates was nil or minor in the field-collected animals. Moreover, the TP values were not significantly different between the animals in the contaminated and the reference habitats because of the high overall uncertainties in the TP estimates (paper IV). Also, the TP estimates based on δ15N in bulk material were more similar between the contaminated and the reference systems than TP estimates based on δ15N values in amino acids. Therefore, the latter method appears more sensitive towards xenobiotics (and, possibly, other environmental stressors) and thus less suitable for TP assessment in contaminated areas. This Thesis improved the overall understanding of the applicability of SIA in stressed systems by establishing relationships between various exposure regimes, physiological responses and the stable isotope signatures in consumers. In model species at low trophic levels, the exposure to xenobiotics was found to significantly affect δ13C and δ15N values, which can be expected whenever physiological responses are detected. However, because of the overall high uncertainty in TP estimates, no significant differences between contaminated and control systems were detected, although the estimated TP were consistently higher in the contaminated systems. Future research should focus on higher trophic levels, in which effects of a greater magnitude can be expected. Moreover, the effects in entire food webs should be addressed rather than single prey–consumer relationships as well as other environmental variables that may contribute to the stable isotope variability in and among systems under various environmental pressures.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Yes
Objectives: We compared δ15N and δ13C values from bone and dentine collagen profiles of individuals interred in famine‐related and attritional burials to evaluate whether individuals in medieval London who experienced nutritional stress exhibit enriched nitrogen in bone and tooth tissue. Dentine profiles were evaluated to identify patterns that may be indicative of famine during childhood and were compared with the age of enamel hypoplasia (EH) formation to assess whether isotopic patterns of undernutrition coincide with the timing of physiological stress. Materials and Methods: δ15N and δ13C isotope ratios of bone collagen were obtained from individuals (n = 128) interred in attritional and famine burials from a medieval London cemetery (c. 1120–1539). Temporal sequences of δ15N and δ13C isotope profiles for incrementally forming dentine collagen were obtained from a subset of these individuals (n = 21). Results: Results indicate that individuals from attritional graves exhibit significantly higher δ15N values but no significant differences were found between burial types for the sexes. Analyses of dentine profiles reveal that a lower proportion of famine burials exhibit stable dentine profiles and that several exhibit a pattern of opposing covariance between δ15N and δ13C. EH were also observed to have formed during or after the opposing covariance pattern for some individuals. Conclusions: The results of this study may reflect differences in diet between burial types rather than nutritional stress. Though nutritional stress could not be definitively identified using bone and dentine collagen, the results from dentine analysis support previous observations of biochemical patterns associated with nutritional stress during childhood.
Division of Behavioral and Cognitive Sciences. Grant Numbers: BCS‐1261682, BCS‐1540208. Office of the Vice President for Research, University of South Carolina. Grant Number: SPARC Fellowship Grant

Southeast Florida’s continual urban expansion will potentially increase anthropogenic pollution in adjacent coastal marine systems. Furthermore, increased nutrient loads could have detrimental effects on the already threatened Florida Reef Tract. The present study uses a stable isotopic approach to determine the sources and the impact of nutrients on the Florida Reef Tract. δ13C and δ15N analysis of macroalgae, sponges, and sediment were analyzed in order to determine nutrient inputs in this region. While δ13C data did not display any significant trends spatially, δ15N values of the majority of biota exhibited a strong East to West gradient with more enriched values close to shore. Relative enrichment in δ15N values were measured for sediments sampled along the Florida Reef Tract in comparison to a pristine Marquesas Keys sediment core. The δ15N data also implies that shoreline anthropogenic nutrients have more nutrient loading implications on reefs than major point sources.

Cotton is the most abundant natural fiber in the world. Many countries are involved in the growing, importation, exportation and production of this commodity. Paper documentation claiming geographic origin is the current method employed at U.S. ports for identifying cotton sources and enforcing tariffs. Because customs documentation can be easily falsified, it is necessary to develop a robust method for authenticating or refuting the source of the cotton commodities. This work presents, for the first time, a comprehensive approach to the chemical characterization of unprocessed cotton in order to provide an independent tool to establish geographic origin. Elemental and stable isotope ratio analysis of unprocessed cotton provides a means to increase the ability to distinguish cotton in addition to any physical and morphological examinations that could be, and are currently performed. Elemental analysis has been conducted using LA-ICP-MS, LA-ICP-OES and LIBS in order to offer a direct comparison of the analytical performance of each technique and determine the utility of each technique for this purpose. Multivariate predictive modeling approaches are used to determine the potential of elemental and stable isotopic information to aide in the geographic provenancing of unprocessed cotton of both domestic and foreign origin. These approaches assess the stability of the profiles to temporal and spatial variation to determine the feasibility of this application. This dissertation also evaluates plasma conditions and ablation processes so as to improve the quality of analytical measurements made using atomic emission spectroscopy techniques. These interactions, in LIBS particularly, are assessed to determine any potential simplification of the instrumental design and method development phases. This is accomplished through the analysis of several matrices representing different physical substrates to determine the potential of adopting universal LIBS parameters for 532 nm and 1064 nm LIBS for some important operating parameters. A novel approach to evaluate both ablation processes and plasma conditions using a single measurement was developed and utilized to determine the “useful ablation efficiency” for different materials. The work presented here demonstrates the potential for an a priori prediction of some probable laser parameters important in analytical LIBS measurement.

Parrotfish are a critical component of the herbivore functional group on tropical coral reefs around the world because they mediate competition that occurs between algae and scleractinian corals. Also, because of their feeding technique, which consists of rasping at the substratum with their beak-like teeth, they play an important role in carbonate turnover and the clearing of reef surface area for the settlement of new sessile organisms. Because of these roles, parrotfishes are an important structuring component of coral reef communities. However, individual species can play different roles depending on their physiology, behaviour and ecology. Despite the possible ecological differences that may exist amongst species, specific roles of the fishes remain unclear as the group is most often studied at higher community levels. This thesis applied stable isotope analysis to differing levels of organisation within a parrotfish community to help elucidate their trophic ecology on coral reefs in Zanzibar. Firstly, blood and muscle tissues were compared to identify differences in their isotope signatures. In other organisms, blood turns over faster than muscle tissue so that muscle tissue represents the diet as integrated over a longer period of time. In most species of parrotfish the blood and muscle δ¹³C signatures were not found to be significantly different, but the δ¹⁵N signatures were significantly different between tissues. This indicated that the δ¹³C signature of both tissues would reveal similar dietary information. Conversely, differences in the δ¹⁵N signature indicated that the nitrogen relationship between tissues was more complicated. Secondly, spatial variability in parrotfish, coral, detritus and macroalgae isotope signatures was assessed at different scales. In macroalgae and coral tissues (zooxanthellae and polyp treated separately), the δ¹³C signatures were shown to differ with depth, presumably because of changes in photosynthetic processes related to depth-associated changes in light. While δ¹⁵N signatures were not affected by depth, all organisms showed enrichment at the Nyange reef, the closest reef to the capital of Zanzibar, Stone Town, presumably reflecting the effects of sewage outfall. These results show that processes that impact the δ¹⁵N signatures of primary producers (macroalgae and zooxanthellae) can be traced to higher trophic levels (coral polyps and fish). Lastly, δ¹³C and δ¹⁵N signatures were used to identify ontogenetic dietary changes in multiple species of parrotfish. Four of the species showed stages that varied from the diets that are normally assumed on the basis of their dentition and feeding technique. This indicates that functional roles based on taxonomy or morphology may fail to include possible ontogenetic dietary changes, and may also fail to elucidate the full impact a species could have on coral reef communities. The conclusions from these studies indicate that the species-specific ecological role of parrotfish in coral reef communities can be complex within and between species, and may differ amongst reefs. In light of the natural and anthropogenic pressures that affect coral reef systems, management decisions based on a more complete understanding of the role of these fish in coral reef communities will help decisions that maintain resilience in these fragile systems.

The analysis of both the digestive gland and the muscle tissue of Lolliguncula brevis showed that fatty acid and stable isotope signatures of the predator changed with time to reflect the signatures found for prey species fed in the experiment. Both short-term (digestive gland) and long-term effects (muscle) of the diet could be established through the analysis of these metabolically different tissues and the present study proved that these methods are viable for the use in reconstructing diets of squid species in the wild. Using this combination of techniques it was possible to identify seasonal and regional differences in the diet of L. forbesi. Ontogenetic differences in feeding could be established with bigger squid taking more varied prey and switching from a predominantly benthic to more pelagic diet. It was furthermore possible to distinguish between squid feeding in coastal and offshore waters respectively. Through the application of either fatty acid or stable isotope analysis to tissues of Todarodes sagittatus, Illex coindetii and Illex argentinus it was possible to determine short-term and long-term trends in the diet and formulate hypotheses as to which ecosystem mainly contributed to the diet. The diet of T. sagittatus was influenced by both benthic and pelagic prey species. Fatty acid profiles indicated a shift from small planktonic prey taken by small squid to a more piscivorous feeding in bigger squid. Similarities found for fatty acid signatures of deepwater fish and T. sagittatus suggest that this species spends part of its life cycle in deeper waters. Fatty acid signatures of I. coindetii indicated an omnivorous diet for this species determined by prey availability in two regions subject to different hydrographical conditions. Stable isotope signatures of I. argentinus indicated a diurnal feeding rhythm and regional differences in feeding in this highly migratory species point towards differences in migration routes from spawning to feeding grounds.

The Middle Iron Age on Öland (around 200-550 AD) is often regarded as a prosperous period witha wealth based on animal husbandry. In this study charred cereals from several Iron Age sites atÖland are studied to answer questions about prehistoric diet and agricultural practices. Themethod used is stable isotope analysis of carbon and nitrogen in the cereals, and one further aim ofthe study is to evaluate this method. The results suggest that there is little need for pre-treatment ofcereals before isotope analysis. Most of the grains analyzed were hulled barley and in all sites thereare indications of intensive manuring, as would be expected in permanent field agriculture. Thering forts of the period may here have been places where an agricultural surplus was gathered.Concerning human diet, the isotope values indicate cereals may have been an important part.Crops may also have been used to feed the livestock, possibly with secondary products like straws,and likely to a different extent in different animal species. Finally, the sites from the Middle IronAge all appears to have been abandoned. Heavy dependence on animal manure may havedecreased the resilience of agriculture, making it more vulnerable to unexpected changes, forexample the climate downturn after 536 AD.
Sandby Borg

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996.
Includes bibliographical references (leaves 46-53).
by Susan Elizabeth Alderman.
M.S.

There are numerous problems associated with the analysis of samples from mass produced goods if the resulting data are intended for use in court. Currently, many methods do not provide a definitive answer to the question if two chemically identical samples share the same provenance, so new techniques are being tested to overcome this problem. Isotope Ratio Mass Spectrometry (IRMS) measures stable isotope abundance, a compound characteristic that can provide information as to the provenance of natural and synthetic substances. The potential use of IRMS to determine both source and origin of natural substances has been tested with some success identifying for example geographical origin of drugs such as heroin and cocaine (Ehleringer et al. 1999). The aim of this thesis was to study the application of stable isotope analytical techniques to two representatives of mass produced goods, namely architectural white paint and wooden safety matches. Existing analytical techniques are not sufficient for the forensic examination of architectural paint. The proposed solution was stable isotope profiling using IRMS. Background studies were carried out to determine potential intra and inter-batch variability of paint samples. This was followed by studies of 51 architectural white paints, which showed the considerable potential of stable isotope profiling when combined with likelihood ratios as a forensic statistical tool. The results from IRMS were compared to other analytical methods. Wooden matches are items commonly encountered at a variety of crime scenes. However prior to this thesis, no established comparative method of forensic analysis existed for this. type of sample. Wooden matches were analysed by IRMS and the results compared to microscopy and X-ray diffraction. Each of the techniques produced complimentary data and allowed the differentiation of two sets of matches seized in an actual criminal investigation. The analysis of burnt wooden matches by IRMS showed considerable potential for even when samoles were burnt. Supplied by The British Library - 'The world's knowledge'

The multi-faith society of medieval Iberia, where Muslims, Christians and Jews co-existed under changing religious political rule, provides a novel setting for the study of diet. This thesis employs carbon (δ13C) and nitrogen (δ15N) isotope analysis to explore variability in diet and resource exploitation between faiths, localities and through time under Muslim and later Christian rule and places the isotopic data in the context of other historical and archaeological evidence. Isotope analysis was performed on bone collagen from 126 animals and 210 humans representing Muslims and Christians, sampled from sites in Jaca, Zaragoza, Albarracín, Valencia, Gandía and Benipeixcar (c.11th -16th centuries AD) that follow a geographical transect from the Pyrenees to the Mediterranean coast, through Aragón and Valencia. Results indicate humans from all locations consumed a diet based on terrestrial plant and animal protein, with a possible input of aquatic resources at Zaragoza, Valencia and Gandía. There were no consistent differences in diet between faiths, however differences were present between contemporaneous populations of Muslims and Christians in Benipeixcar and Gandía and successive populations of Muslims and Christians in Valencia. A north-south, inland-coastal trend was revealed in the exploitation of C4 plants (millet, sorghum, possibly sugarcane for cattle fodder) which made a significant contribution to the diets of some animals and humans, particularly in the south. Social status and the rural/urban nature of settlements influenced the extent of this exploitation. Dietary diversity was observed in Valencia, particularly in the Islamic period and the presence of immigrants among the populations of this city and Jaca is hypothesised. Sex-based differences in diet were present at some, but not all sites. Variable isotope ratios for animals at almost all sites demonstrates the variety of animal husbandry practices and ecological niches that were exploited during the medieval period in Spain.

Stable isotope (SI) ratios of carbon (δ13C) and nitrogen (δ15N) are now widely used as biomarkers in ecological studies to provide information about food web structuring. However, understanding trophic relationships using SI analysis requires not only knowledge of SI values of predator and prey, but also accurate discrimination factors (DFs), which can differ among species and by physiological state. This thesis examined three questions using captive birds from the South African Foundation for the Conservation of Coastal Birds (SANCCOB). First, the effects of ontogeny on δ13C and δ15N ratios of African penguins (Spheniscus demersus) were assessed. Blood samples were collected from penguins in four age classes (P3 chicks, blues, juveniles and adults) concurrently with their diet (sardine (Sardinops sagax) and formula). Second, to assess the influence of breeding physiology on SI ratios, the blood of ten breeding pairs of penguins was sampled over a five-month period from June to October 2016. Following laying, each pair was categorised into one of three (four for whole blood) egg production phases (initial yolk deposition, rapid yolk deposition and post-laying) and their influences on SI ratios were tested. Third, species differences in DFs were evaluated for African penguins, kelp and Hartlaub’s gulls (Larus dominicanus and L. hartlaubii), greater crested terns (Thalasseus bergii) and Cape cormorants (Phalacrocorax capensis). Flying birds were mostly fed sardine with a small but unknown amount of sardinella (Sardinella aurita), DFs were therefore estimated for a 50:50 sardine:sardinella diet, a 75:25 sardine:sardinella diet and a 100% sardine diet for each flying bird species. The DFs were assessed for the whole blood (WB), red blood cells (RBC), plasma (PL) and delipidated plasma of the penguins, and only WB for the flying birds as well as flesh, whole fish, delipidated flesh and delipidated whole fish for fish species, and for formula. Results indicated that age influenced both the δ13C and δ15N of WB, only the δ15N of RBC and the δ13C of delipidated PL. The assessment of breeding physiology yielded a significant interaction between the effects of egg production phase and sex on the δ13C of WB; females had significantly lower δ13C in the rapid yolk deposition phase than the other two phases and all males. The δ13C of PL was affected only by sex, with females having a significantly lower δ13C value than males. Neither physiological state nor sex influenced the other blood components. Differences were found among the three DFs in the non-penguin species, but not for all consumer – prey tissue combinations. There were also significant differences among species with a DF calculated from a diet with the most probable prey proportions eaten. Depending on the combination of consumer and prey tissue used to calculate the DF, a different conclusion regarding trophic information can be reached. A literature review updated with the present data showed that no general pattern or grouping of similar species with regards to DF values could be drawn, highlighting the importance of determining species- and tissue-specific DFs. Thus age, egg production, tissue and species all influenced the SI values of bird blood and therefore their DFs. Not all physiological conditions affect all blood components in the same way, making different components more or less sensitive to physiological influences. Though their influence is at a small enough scale that it is unlikely to hamper correct conclusion in ecological studies, it is crucial that these factors are considered when using SI analysis (SIA). When uncertainties exist for some coefficients in wild studies, SIA should therefore be combined to other dietary techniques to determine the food web structure as best as possible.

The black bear (Ursus americanus) is an iconic species with cultural, economic and ecological importance in Vermont, USA. Bears exhibit a highly variable diet, and few studies have described bear diet in the state. Information on diet may provide insight into foraging behavior, thus allowing managers to better assess patterns of human-bear conflict. My objectives were to estimate the relative contribution of food items to bear diet and how factors including sex, habitat, food availability, and nuisance status describe patterns of consumption. I collected samples from bears and major food groups including C3 plants, white-tailed deer (Odocoileus virginianus), corn (Zea mays), and human foods, then quantified diet using stable isotope analysis. Samples were collected from 71 bears, 547 plants, and 38 deer throughout Vermont. I also collected 12 corn samples, and 20 human hair samples to represent anthropogenic foods. I determined δ13C and δ15N isotope values for all samples, then used Bayesian mixing models to estimate the contribution of foods and effect of each factor on proportional contribution estimates. Nuisance status best described patterns of diet over other factors. Median percent contributions for non-nuisance bears were 73.2% C3 plants, 23.8% corn, 1.9% human foods, and 0.5% deer. Median percent contributions for nuisance bears were 64.6% C3 plants, 28.9% corn, 3.2% human foods, and 0.7% deer. Factors such as sex, habitat, and food availability exerted less effect on diet than expected. Proportional contribution of meat was lower than in some other parts of North America, suggesting bears forage differently in Vermont. Results provide the first statewide estimate of bear diet and indicate corn may represent a much larger component of diet than previously thought. In particular, bears labeled as nuisance animals may forage on greater proportions of corn throughout the year.

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Ephemeral ponds are vulnerable aquatic habitats which are difficult to protect given their dynamic nature and sensitivity to degradation during dry periods. Little information is available on these habitats in austral regions, with almost no information on food-web structure and complexity. The study aimed to assess trophic interactions among dominant organisms in an ephemeral pond food web, and investigate the importance of autochthonous and allochthonous carbon, using 13C and 15N isotopes. Results of the investigation suggest that the food web comprised four trophic levels, with the top predators being Notonectids (Notonecta sp.) and diving beetles (Cybister tripunctatus (Olivier)). Intermediary trophic levels comprised zooplankton (daphniids and copepodids), macroinvertebrates (e.g. micronectids and molluscs) and tadpoles. Generalist feeders dominated the higher trophic levels (>3) with specialists comprising the lower trophic levels (≤3). The consumers preferred autochthonous fine particulate organic matter, epiphyton and submerged macrophyte organic matter sources over allochthonous sources. Autochthonous organic matter was transferred to the food web via zooplankton and select macroinvertebrates including Micronecta sp. and Physa sp. The food-web structure within the pond appeared to reflect the secondary stage of trophic structural complexity in the evolution of ephemeral ponds over the course of their hydro-period.

The Antarctic Peninsula is one of the fastest warming regions on the planet. In the past 50 years, the temperature has increased by more than 2⁰C, leading to the retreat of large areas of the ice shelves fringing the Antarctic Peninsula. Recent environmental changes in the Antarctic Peninsula are well documented by meteorological and remote sensing data, but the behavior of the Holocene atmosphere-ocean-cryosphere system is not well understood. In this study foraminifera are used as a proxy for Holocene oceanographic conditions in the Gerlache Strait, western Antarctic Peninsula. The most abundant foraminifera identified in this study include the agglutinated taxa Miliammina arenacea and Paratrochammina lepida, which are associated with cold, saline water masses and periods of high sea-ice production. The most abundant calcareous species identified is the opportunistic Fursenkoina spp., which is associated with ice-proximal conditions and fresh water input due to glacial melting. Deglaciation of the Gerlache following the Last Glacial Maximum is indicated by the appearance of foraminifera and diatoms at ~7700 years BP. The Post-Deglaciation period is characterized by high frequency variation in foraminiferal assemblages between abundant agglutinated and calcareous taxa, indicating unstable glacial conditions. The beginning of the Mid-Holocene Climactic Optimum (MHCO) is indicated by a substantial decrease in sedimentation rates and a shift to more stable foraminiferal assemblages. A decline in diatom abundance and the absence of calcareous foraminifera indicates a glacial readvance at 6030 years BP. At 4470 years BP the calcareous taxa including Fursenkoina spp. become dominant, indicating glacial retreat and input of fresh water into the water column. After 3240 years BP agglutinated taxa are once again dominant and calcareous taxa absent. This marks the beginning of the Neoglacial period and the presence of colder, more saline shelf waters in the Gerlache Strait. Stratification of the water column is apparent during the Post-Deglaciation period and the latter part of the MCHO. A difference in δ18O values of >0.5 per mille between benthic and planktonic foraminifera indicates the presence of a less saline surface water layer which may be the result of freshwater input due to glacial melting and an estuarine circulation regime.

Stable isotope, stratigraphic and micropalaeontological studies provide an insight into the preservation of Tertiary global cooling episodes in shelf carbonate rocks from the Mandamus-Pahau District in North Canterbury. Local shelf carbonate isotope analysis (δ13C and δ18O) shows these shelf rocks have not retained the original sea-water isotopic signature but have been altered during burial diagenesis. The Palaeocene to Late Eocene Coal Creek Formation from this district is a glauconite-rich, inner shelf unit transitioning to a mid-outer shelf environment. Separation of this unit from the Mid-Late Oligocene Cookson Volcanic Group is marked by a ~3-4 Ma hiatus representative of the Marshall Paraconformity. The Marshall Paraconformity is inferred throughout the district due to a distinct break in style and sedimentation from the Late Eocene until the Mid-Late Oligocene. Cookson Volcanic Group tuffaceous beds and pillow basalts represent localised intra-plate volcanism that occurred prior to the deposition of the Late Oligocene Flaxdown Limestone. This Oligocene limestone represents a mid shelf, bryozoan and algal-rich grainstone. Widespread development of this carbonate unit illustrates the absence of tectonically derived sediments prior to the deposition of the Pahau Siltstone Member. The Early Miocene marks the initiation of a new tectonic regime in New Zealand, with the deposition of the inner shelf, quartz-rich Pahau Siltstone Member due to tectonic associated uplift and erosion. These shelf sediments proved inadequate as a record of global climate excursions, with grainsize and the dominance of burial diagenesis limiting their use in global isotope records. Shelf sediments seen in this study mostly consist of grainstones or sandstones with the coarse grainsize of these units allowing a high flow of pore fluids through sediments. These pore fluids occurred out of equilibrium with bioclasts within these Tertiary units, increasing the alteration potential of bioclasts. This thesis provides strong evidence for problematic global isotopic signatures in local shelf sediments due to grainsize and diagenesis, yet other studies have proved it is possible to reconstruct the global isotope curve from shelf sediment records. Accurate shelf records depend on proxies less prone to diagenetic alteration that act as a reliable gauge of local and global environmental change.

Medieval Portugal, tucked between a Christian north and an Islamic south, and at a crossroad between Africa and Europe, saw the birth and development of a multi-faith and multi-cultural society. Muslims and Christians co-existed in this region, shaping a unique pluralistic society, first under Islamic political control and later under Christian rule following the Christian conquest of the 12th century. This thesis applies carbon (δ13C) and nitrogen (δ15N) isotope analysis to characterises early and late medieval diet under Islamic (8th-12th) and Christian rule (12th-15th), exploring the impact of a shifting political system, status and faith onto economy, food availability and consumption. Analysis of stable isotopes of carbon (δ13C) and nitrogen (δ15N) was performed on bone collagen from 176 animals and 251 humans including Muslims and Christians sampled from sites covering a north-south trajectory (Laranjal, Coimbra, Lisbon, Setubal, Beja, Silves and Loulé) with a date range between the 8th and 15th centuries. Results indicate that a faith-related difference in diet exists but is also related to chronology and geographical location. Early medieval Muslim diet is based on animal protein and C3 plants with possible inputs of low trophic level fish in Setubal and Loulé; while bigger proportions of marine fish appear in the diet of late medieval Muslims in Lisbon. Early medieval Christian diet is based on terrestrial resources with a reliance on C4 plants in Coimbra; while late medieval Christian sites in southern Portugal show a reliance on marine resources. Results show a difference in diet between early and late medieval sites with a clear change in economy possibly brought about by the Christian conquest. Multi-faith sites (Lisbon, Beja and Silves) show an increment of at least 11% in the quantity of marine protein included in the human diet of Muslims and Christians from the early to the late medieval period.

Parasitism is accepted as being an essential driver in the organization of biological communities. However, although there are estimated to be more parasitic than free-living organisms, parasites have been largely neglected from ecological studies and we have a relatively limited understanding of their trophic ecology. Hence, in order to incorporate parasites into food-web models and ecological studies, basic trophic interactions between parasites and their hosts need to be assessed. Here, I investigated host-parasite interactions using stable isotope analyses on a broad range of marine fish hosts and their associated copepod and monogenean gill parasites. The study also provides insight into the gill parasite diversity of a number of host species from South African marine waters. Seventeen species of fish hosts, ranging from lower to upper trophic levels, were collected from South African waters in 2015 and 2016 during surveys conducted by the Department of Agriculture, Forestry and Fisheries from South African waters. These host species were; Thunnus albacares, Thunnus maccoyii, Thunnus alalunga, Thunnus obesus, Isurus oxyrinchus, Prionace glauca, Xiphius gladius, Brama brama, Thyrsites atun, Seriola lalandi, Sarda sarda, Genypterus capensis, Merluccius paradoxus, Merluccius capensis, Lampanyctodes hectoris, Sardinops sagax and Trachurus capensis. The head region, gills and operculae from a total of 1513 fish were examined and any ectoparasites removed, identified down to the lowest taxonomic level possible, and counted. A total of 32 parasite taxa, comprising 20 copepods and 12 monogenean species, were recorded. Two new host records and 15 new geographic records for South Africa were catalogued. The new host records are Mazocraes sp. infecting T. atun, and Caligus dakari infecting T. capensis. The new locality records consist of Euryphorus brachypterus recovered from T. alalunga and T. obesus, Pseudocycnus appendiculatus recovered from T. albacares, T. alalunga and T. obesus, Hexostoma sp. recovered from T. albacares and T. obesus, Nasicola klawei recovered from T. albacares and T. obesus, Tristoma adcoccineum recovered from X. gladius, Eobrachiella elegans and two species from the genus Parabrachiella recovered from S. lalandi and Anthocotyle merlucci recovered from M. paradoxus and M. capensis. These new records have substantially contributed to the known parasite biodiversity within the South African marine environment. Host-parasite interactions between 15 species of fish host and their copepod and monogenean gill parasites were investigated by means of stable isotope analysis. Host white muscle tissue, host gill tissue and parasite samples were analysed for their carbon and nitrogen isotopic signatures. Results indicated that δ¹⁵N is tissue-specific, with host white muscle tissue showing significantly greater enrichment in ¹⁵N compared to host gill tissue (n =60; Z=5.66843; p<0.00001), and as gill tissue is what the parasites are presumably feeding on, host gill tissue was therefore selected as the most appropriate proxy.

This project investigates the relationship between health and diet in medieval Portugal by combining data on the occurrence of osteoporosis with information on past diet derived from stable isotope ratios. The aim of this project is to identify whether different sources of protein influenced the prevalence of osteoporosis in three populations. Individuals from three different regions of Portugal were previously evaluated for bone mineral density at the University of Coimbra, Portugal, and bone samples from 91 of these individuals underwent stable isotope analysis at the University of Alaska Fairbanks. Collagen suitable for isotopic analysis was extracted from all individuals and indicated a negative correlation between bone mineral density (BMD) and carbon and nitrogen isotope values for females at one site and a positive correlation for males at another site. These results, combined with the lack of a clear relationship between BMD and nitrogen isotope values for the other subgroups, suggest a complicated relationship between dietary protein source and the occurrence of osteoporosis. While samples sizes are small, the data indicate that future analysis is warranted, particularly considering the high incidence of osteoporosis and the economic and individual strain of the disease.

La gestion et la conservation des pêcheries sont problématiques pour la plupart des chondrichthiens; cela tient principalement au manque de données scientifiques causé par les défis logistiques impliqués par les prélèvements par grandes profondeurs. De plus, plusieurs les techniques analytiques, à l’exemple du contenu stomacal et des mesures morphologiques, demandent des quantités d’échantillons importantes difficilement obtenues. De nouvelles techniques exigent moins d'échantillons, en particulier celles mettant en oeuvre la biochimie qui sont de plus en plus utilisées pour résoudre des questions écologiques et biologiques complexes au niveau individuel et démographique des populations. Cette thèse a testé plusieurs techniques biochimiques (analyses de lipide, mercure, et isotope de carbone et azote) pour mieux comprendre les aspects de la reproduction, de l'écologie trophique, de l'amplification du mercure et de la physiologie de chondrichthiens des profondeurs. La plupart des espèces font partie de l'Ordre des Squaliformes. D'autres espèces appartiennent à différentes Familles: Chimaeridae, Rhinochimaeridae, Scyliorhinidae et Hexanchidae. Tous les échantillons ont été capturés dans les filets de pêcheurs dans les eaux du plateau continental et des marges du sud-est de l'Australie. L’analyse de la composition en lipides de différents tissus révèlent que le foie des chondrichthiens est riche en lipides (38 à 70% de la masse des tissus humides), en majeure partie des lipides neutres et des acides gras mono-saturés. Le foie est un tissu multifonctionnel, qui joue un rôle essentiel dans la distribution de la biosynthèse lipidique, le stockage de l’énergie et la régulation de la flottaison. A l’inverse, le tissu musculaire est un organe structurel, à faible concentration en lipide (<2 %) qui se compose essentiellement de lipides polaires. La composition des lipides rénaux et pancréatiques montre que leur fonctionnement métabolique est complexe. L'analyse des lipides des organes reproducteurs a révélé que l’énergie utile à la gestation chez les adultes chondrichthiens en pré-ovulation nécessite un pourcentage important de lipide (follicule ovarien 18 à 34 %). Les variations de triacylglycérols (8 à 48 %), des éthers diacylglycéryls (0,2 à 28 %) et des cires (0,5 à 20 %) ont été observées dans tous les échantillons. Ces variations impliquent l'utilisation de classes lipidiques multiples pour favoriser le développement embryonnaire. Les réserves maternelles sont différentes entre espèces ovipares et vivipares et entre les élasmobranches et les holocéphales. L’allocation la plus important de lipides est trouvée chez les requins vivant dans les environnements les plus profonds. Cette observation suggère que leur fécondité est plus faible et que leur vulnérabilité face à la pêche est plus importante. Le régime alimentaire des requins a été déterminé par des techniques complémentaires: traceurs lipidiques et analyses du contenu stomacal. 41 taxons de proie ont été identifiés. Ils étaient surtout composés de poissons et de céphalopodes du domaine demersal. En utilisant les profils des acides gras, la variabilité de la composition de nourriture a été établie pour chaque espèce en associant la signature de ces profils dans les tissus des chondrichthiens aux profils de plusieurs proies. Les deux techniques ont montré que les chondrichthiens sont des prédateurs opportunistes qui consomment une large gamme de proie. Les concentrations en mercure et sa distribution des tissus ont été examinés pour accéder à sa bioamplification dans ce type d’organisme et de déterminer des niveaux de contamination pour la consommation publique. Le mercure total (THg : toutes formes chimiques confondues) et le méthylmercure (MeHg : la forme la plus toxique et bioaccumulable) ont été dosées. Pour la plupart des espèces, les niveaux de THg étaient supérieurs au seuil maximal recommandé par les législations en vigueur dans plusieurs pays dont l’Australie (>0,1 mg kg-1 pois humide, ph) et une concentration aussi forte que 6,6 mg kg-1 (ph) a été enregistrée. L'
Analyse de spéciation a montré que le mercure est présent à plus de 91 % sous forme de MeHg, et même avec des taux supérieurs à 95 % chez les espèces des environnements les plus profonds. Les concentrations maximales en THg ont été trouvés dans les tissus musculaires (59 à 82 % de charge corporelle). Les reins et le foie possèdent aussi des taux élevés, respectivement de 0,3 à 4,2 et 0,5 à 1,5 mg kg-1 (ph), tandis que la peau enregistre les concentrations les plus faibles (> 0,3 mg kg-1, ph). Cette étude de l’organotropisme permet de conclure que les reins et le foie sont associés au métabolisme du métal, à l'élimination et au stockage à court terme, alors que le muscle est le sites le plus important du stockage du mercure à long terme. Les isotopes stables de carbone et d’azote ont été utilisés pour évaluer l'influence de la position trophique (d15N) et de la source de carbone (d13C) sur l'accumulation du THg chez les chondrichthiens. Le d15N varie entre 12,4 à 16,6 ‰ démontrant la large gamme de positions trophiques occupées par ces espèces. La variation interspécifique du d13C est quant à elle minimale (–18,7 à –17,1 ‰). Les concentrations en mercure notées chez la plupart des requins augmentent en fonction de la taille, de la position trophique (d15N) et du stade de maturité de l’animal. Dans la communauté des chondrichthiens des profondeurs on observe des taux modérés de bioamplification du mercure, ceci est révélé par la faible pente de la relation, log (THg mg kg-1 ww) = 0,2 (d15N) – 2,4 (R2 = 0,35 ; P <0,05). Le THg et les acides gras de 61 espèces appartenant aux niveaux trophiques intermédiaires ont été analysés dans le but d’étudier les régimes alimentaires des proies et la bioaccumulation de ce métal à travers la chaîne alimentaire démersale. L'utilisation intégrée de ces techniques biochimiques a fourni des données fondamentales sur la reproduction, l'accumulation en mercure et l'écologie trophique des chondrichthiens des profondeurs. La compréhension de ces fonctions est impérative non seulement pour la mise en place d’une gestion durable des pêcheries, mais aussi pour la protection des habitats des chondrichthiens et leurs écosystèmes associés
For most deepwater chondrichthyans, fisheries and conservation management is problematic, largely due to the lack of scientific data resulting from inherent logistical challenges working within deep-sea environments. Furthermore, many conventional analytical techniques (stomach content analysis and morphometrics) require large sample sizes and are often quantitatively inadequate. Thus, new and more robust methods requiring fewer specimens are needed. Biochemical ‘tracer’ techniques are increasingly being used to resolve complex ecological and biological questions at individual species and population levels. This research explored the integrated use of multiple biochemical techniques (lipid and fatty acid profiling, stable nitrogen and carbon isotope and mercury analysis) to understand aspects of the reproduction, feeding ecology, metal accumulation and physiology of deepwater chondrichthyans. Most were from the Order Squaliformes. Other species include those from the Families: Chimaeridae, Rhinochimaeridae, Scyliorhinidae and Hexanchidae. All specimens were caught as fisheries bycatch from the continental slope waters off southeast Australia. The examination of lipid composition and partitioning revealed that deepwater chondrichthyans have large, lipid rich (38–70 % wet weight, ww) livers high in neutral lipids and monounsaturated fatty acids. Liver is a multifunctional tissue, playing a vital role in lipid distribution and biosynthesis, buoyancy regulation and storage. In contrast, muscle is a structural organ, low in lipid (<2 %) and consisting primarily of polar lipids. Lipid composition of kidney and pancreas show that they, too, have complex roles in lipid metabolism and storage. Lipid analysis of reproductive tissues revealed high maternal investment in deepwater chondrichthyans as indicated by high lipid content in mature pre-ovulated ovarian follicles (18–34 %). Variable levels of triacylglycerols (8–48 %), diacylglyceryl ethers (0.2–28 %) and wax esters (0.5–20 %) were observed in all specimens, demonstrating the use of multiple lipid classes to fuel embryonic development. The maternal provisions differed between oviparous and viviparous species and between elasmobranchs and holocephalans. Greater lipid investment was displayed by sharks living in deeper environments, suggesting lower fecundity and increased vulnerability to fishing. Diet was examined by complementary lipid biomarker and traditional stomach content techniques. A total of 41 prey taxa were identified using stomach content analysis and consisted mainly of bathyal-demersal fish and cephalopods. Using multidimensional scaling analysis, the extent of variability in composition within each species was determined by grouping the signature fatty acid profiles of shark tissues with profiles for demersal fish, squid and crustaceans. Both techniques showed that deepwater chondrichthyans are opportunistic predators, and that there is some degree of specialisation and overlap between them. Total (THg) and inorganic (monomethyl, MeHg) mercury concentrations and tissue distribution were examined to determine the extent of biomagnification and evaluate levels for human consumption. Mean THg levels for most species were above the regulatory threshold (>0.1 mg kg-1 ww) and levels as high as 6.6 mg kg-1 ww were recorded. Speciation analysis demonstrated that 91% mercury was bound as MeHg with higher percentages (>95%) observed in species occupying deeper environments. Higher levels of THg were stored in muscle which accounted for between 59–82% of the total body burden of mercury. High levels were also found in kidney (0.3–4.2 mg kg-1 ww) and liver (0.5–1.5) with lower levels observed in skin (>0.3). Both the kidney and liver are likely to be associated in metal metabolism, short term storage and elimination procedures, while the muscle is the major site for long term storage. Stable isotopes were used as natural dietary tracers, to further evaluate dietary relationships and to assess the influence of trophic position (d15N) and carbon sources (d13C) on THg accumu
lation. Isotopic nitrogen (d15N) values ranged from 12.4 to 16.6 ‰ demonstrating a broad range of trophic positions. Minor variation in carbon (d13C) enrichment was observed between species (–18.7 to –17.1‰). In most shark species, mercury concentrations increased with size, trophic position (d15N), and maturity stage, but not between location or collection period. As a community, deepwater sharks demonstrated moderate rates of THg biomagnification, as indicated by the regression slope (log (THg) = 0.2 d15N – 2.4, R2 = 0·35, P < 0·05). THg and fatty acid analyses of 61 mid-trophic species were measured for their usage in studies of diet in high-order predators and mercury bioaccumulation in the extended demersal food chain. The integrated use of these biochemical techniques has provided fundamental data on the reproduction, metal accumulation and trophic ecology of deepwater chondrichthyans. Understanding these parameters is imperative not only for the implementation of sustainable management but for habitat protection of deepwater chondrichthyans and their associated ecosystems

The Laramide Rocky Mountains in western U.S.A is an important topographic feature in the continental interior, yet its formation and evolution are poorly constrained. This study uses the oxygen and strontium isotope geochemistry of freshwater bivalve fossils from six Laramide basins in order to reconstruct the spatial evolution of the paleotopography and Precambrian basement erosion in late Cretaceous-early Eocene. In addition it uses the sedimentology, detrital zircon U-Pb geochronology, and isotope paleoaltimetry of early Eocene sedimentary strata to constrain the tectonic setting, paleogeography and paleoclimate of the Wind River basin. Annual and seasonal variation in ancient riverwater δ¹⁸O reconstructed from shell fossils shows that the Canadian Rocky Mountains was 4.5±1.0 km high in late Cretaceous-early Paleocene, and the Laramide ranges in eastern Wyoming reached 4.5±1.3 km high, while the ranges in western Wyoming were 1-2 km high in late Paleocene. The ⁸⁷Sr/⁸⁶Sr ratios of riverwaters reconstructed from the same fossils show that Proterozoic metamorphic carbonates in the Belt-Purcell Supergroup were not exposed in the Canadian Rocky Mountains during Late Cretaceous-early Paleocene, but that Precambrian silicate basement rock was exposed and eroded in the Laramide ranges during late Paleocene-early Eocene. The sedimentary environment of the early Eocene Wind River basin changed from gravelly fluvial and/or stream-dominated alluvial fan to low-sinuosity fluvial systems. Tectonic uplift of the Washakie and Wind River Range in early Eocene formed the modern paleodrainage system, although the elevation of the basin floor was only ~500 m high at that time, and early Eocene paleoclimate is more humid than modern climate.

This thesis investigates continuity and change of human diet in York from the Roman to the Post-Medieval period through the analysis of stable isotope ratios of carbon (813C) and nitrogen (815N ) in the collagen of archaeologicalh uman and animal bones,. The human sample comprises 311 individuals from the Roman cemeteries of Trentholme Drive and Blossom Street, the Anglian site of Belle Vue House, the Earlier and Later Medieval phases of St. Andrew, Fishergate as well as Later and Post- Medieval burials ftom the church of All Saints, Pavement. In addition 145 samples of mammals, fish and birds from the sites of Tanner Row and Fishergate were analysed. The isotope data indicate that the diet in all periods was based predominantly on terrestrial plant and herbivore protein, but with additional minor input from probably several different 15N enriched sources, such as pork, poultry and eggs as well as aquatic (freshwater and marine) protein. In most cases, the complex dietary signals could not be completely resolved by carbon and nitrogen stable isotope analysis. The results nevertheless suggest dietary variation between all archaeological periods. The most significant change in diet, however, was the addition of significant quantities of marine fish which is evident for the first time in a group of young males from the Earlier Medieval cemetery at Fishergate. In the Later Medieval priory phase of the same site, marine foods were almost universally consumed, although in greatly varying proportions. They still remain prominent in the diet of several of the 18'h century burials from All Saints. The isotopic data-set from York suggest several interesting trends of dietary variation within single populations. Notably, it provides further evidence that marine foods played a prominent role in the diet of the social elite in Roman Britain. For the Later Medieval period, isotope analysis can identify dietary variation between males and females as well as differences between individuals buried in various locations on the grounds of the Fishergate priory. The diets of monastic and high-status lay individuals, however, do not appear to be sufficiently different to be distinguished by isotopic data. in conclusion, this thesis establishes that stable isotope can contribute significant new information to research in the early historic periods. It also demonstrates the vast potential of diachronic investigations for stable isotope applications in archaeology.

Understanding the effect of food abundance on feeding behavior can benefit conservation efforts in many ways, such as to determine whether impacted environments need food supplementation, whether different locations of threatened species contain different food abundances, or whether reintroduction sites are missing key components of a species' diet. I studied the relationship between feeding behavior and food abundance in the Lower Keys marsh rabbit (Sylvilagus palustris hefneri), an endangered subspecies endemic to the lower Florida Keys. Specifically, my study set out to measure the relative abundance of the primary plants within the natural habitat of the Lower Keys marsh rabbit and estimate the proportion of each of these plants within the rabbit's diet. With this information, I tested the following hypotheses: first, the Lower Keys marsh rabbit selectively feeds on specific plants; second, that diet does not differ among sites; and third, that diet is not affected by food abundance. Using stable isotope analysis, I determined that two plants were prominent in the rabbit's diet: a shrub, Borrichia frutescens, and a grass, Spartina spartinae. These two species were prominent in the rabbit's diet in most patches, even where they were relatively rare, suggesting the rabbits are indeed selectively feeding on these species. In addition, although diet did differ among patches, selective feeding was apparent in all cases. Overall, this study determined that certain food types are important food sources for the federally endangered Lower Keys marsh rabbit and that these rabbits do not feed on plants based on plant abundance. This knowledge can be directly applied to reintroduction and restoration efforts for the Lower Keys marsh rabbit. More generally, the methods used in this study can be applied to other species of concern in order to address questions associated with diet requirements and foraging behavior.
ID: 030423084; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2010.; Includes bibliographical references (p. 33-39).
M.S.
Masters
Department of Biology
Sciences

Release of different nitrogen compounds can cause eutrophication in lakes and rivers whichcan lead to oxygen-free environments in bottom water and in the sediment and can in turnlead to fish-deaths. Ammonium can be toxic to biota and nitrate can in high concentrationeven be toxic to humans. WHO has released a limit for nitrate concentration in drinking waterof 10mg/l. The LKAB mine in Kiruna is the largest underground iron mine in the world and isprospecting, mining and refining iron ore, with an annual production of around 28 milliontons. Release of different nitrogen compounds as a result of the explosives used during themining operations has been a known problem for some time; however the processes affectingnitrogen during the water transport have never been fully investigated. The main objective of this MSc thesis is to determine if changes in nitrogen and oxygenisotope composition can be used as a tracer for nitrogen transformation processes in the minewater at LKABs underground mine in Kiruna. Water samples were collected at key points in the water transport system and were analyzedfor isotopic composition. Isotopic and chemical data revealed two different sources of nitrateand ammonium, undetonated explosives and leachate from waste rocks. Three differentnitrogen changing processes affecting concentration of nitrate and ammonium were found:ammonium volatilization, nitrification and sorption. It was not possible to quantify theseprocesses individually. No processes which decrease the nitrate concentration were found.

Blooms of nitrogen fixing cyanobacteria (NFC) occur in many freshwater and marine systems, including the Baltic Sea. By fixing dissolved nitrogen, they circumvent general summer nitrogen limitation, while also generating a supply of novel bioavailable nitrogen for non-diazotrophic primary producers and ultimately supporting secondary production. Elucidating trophic links between primary consumers and NFC is essential for understanding role of these blooms for secondary production. However, until recently, there was no reliable method to quantify individual prey species for zooplankter feeding in situ. The development of PCR-based methods to detect prey-specific DNA in the diet of consumers, including microscopic animals, allows identification and quantification of trophic linkages in the field. Using molecular diet analysis in combination with egg production measurements, biochemical markers of growth and condition; and stable isotope approach, we explored a possibility to determine (1) whether cyanobacteria are grazed and assimilated by mesozooplankters (Papers I and II), (2) which species/groups are particularly efficient consumers of cyanobacteria (Papers II and III), and (3) how feeding on cyanobacteria affects zooplankton growth and development (Paper I and III). Taken together, these laboratory and field observations, provided evidence that NFC contribute to feeding and reproduction of zooplankton during summer and create a favorable growth environment for the copepod nauplii (Paper I). The favorable growth conditions for juvenile copepods observed during NFC blooms were hypothesized to be mediated by picoplankton that take up bioavailable nitrogen exuded from cyanobacterial cells. This hypothesis found support in Paper II that provided quantitative estimates for the direct picocyanobacteria → mesozooplankton pathway, with highest weight-specific consumption observed in nauplii. Further, using field observations on zooplankton and phytoplankton development during a growth season in the northern Baltic proper, we found that NFC nitrogen is assimilated and transferred to zooplankton via both direct grazing and indirectly through grazing on small-sized phyto- and bacterioplankton (Paper III). Finally, these and other findings emphasizing the importance of NFC for Baltic Sea secondary production during growth season were synthesized to show that diazotrophic nitrogen enters food webs already at bloom initiation (Paper III) and is transferred via multiple pathways to pelagic and benthic food webs and, ultimately, to fish (Paper IV).

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Accepted.

Food web structure is of underlying importance to ecological functions and processes. Whilst it is understood that a range of biotic and abiotic factors affect structure, relatively little is known of the role of biodiversity per se in structuring food webs. In this thesis I utilise novel multi-dimensional estimates of food web structure based on stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) to quantify structural responses to changing community diversity. I additionally investigate methodological aspects of sample preparation and stable isotope quantifications of food chains. Using an arthropod prey-predator system, in chapter 2 I demonstrate that tissue selection and lipid extraction are important methodological procedures for deriving accurate δ15N and δ13C signatures. In chapter 3 I test the utility of δ15N to quantify food chain length, and δ13C to trace primary energy sources through to end consumers. Bayesian resampling of variance in sample means for plant and arthropod food chains produces robust isotopic estimates that match known food chain length well despite some error variance, and estimates of δ13C-range that trace trophic transfers. Chapter 4 represents a change in system from lab to field as I determine δ15N and δ13C signatures for plant and invertebrate species within three grassland communities representing a gradient of biodiversity. Quantifications of community bivariate isotopic space using isotopic metrics revealed that greater taxonomic richness increased both diversity of resource space exploited and overlap in resource space. These results therefore suggest that loss of diversity affected structure through altering relative patterns of niche partitioning in resource exploitation amongst community members. In chapter 5, I additionally find evidence that grassland management mediated changes in food web compartmental structure that were associated with differences in generalist invertebrate predator feeding habits. Taken together, these findings develop and demonstrate the utility of isotopic approaches to quantifying food web structure, and provide evidence of important mechanisms by which biodiversity affects food web structure. I conclude that the preservation of natural food web structure and trophic dynamics are further reasons for halting loss of biodiversity.

This thesis deals with a medieval material from Rounala in Karesuando parish, Norrbotten county, Lapland. The aim is to reconstruct the diet and mobility patterns. It is through carbon, nitrogen and sulphur stable isotopes and radiocarbon that both pastoralist traits and whether which part Christianity played in the burial traditions of these human remains is being studied. Another aim is to discuss the repatriation issue as these remains are subjected to. The results mainly show that all individuals had a mixed diet and no pastoral way of living has been established. Furthermore, individual 3 is suffering from pathological changes. With radiocarbon dates ranging from 1300 to 1720 AD, two groups can be distinguished as to whom had been buried before and after the construction of the church. And repatriation is being discussed as an issue to who have ownership over ancient remains.

Den här uppsatsen behandlar ett antal individer begravda mellan 800 e.Kr. och 1150 e.Kr i ett tidigt kristet gravfält kring ruinen av Varnhems gårdskyrka. Av speciellt intresse är den placeringen som gravarna har i förhållande till kyrkomurarna och vad dessa placeringar innebär statusmässigt. Analys av stabila isotoper har därför utförts på de manliga individerna  så att deras diet kan faställas och agera som en markör för vad som känneteckas som hög och lågstatus bland de begravda männen i Varnhem.