Effective population management of green sea turtles (Chelonia mydas) necessitates understanding the temporal variation in foraging grounds used in ontogenetic stages, and the effect that the assimilated diet within those habitats has on nutritional gain, growth and eventual reproductive output. Texas coastal waters provide foraging grounds critical to meeting the nutritional needs of green turtles during early life history. To characterize temporal shifts in foraging strategy stomach contents combined with stable carbon (delta13C) and nitrogen (delta15N) isotopes of scute tissue were examined across size classes of stranded juvenile green turtles from the middle and lower Texas coast during 2007-2010. Findings from dietary analysis generally corroborated those from stable isotopes in scute samples. Results indicate green sea turtles exhibit multiple shifts in diet and habitat along the Texas coast. Although isotope values in the tissues of some <25 cm SCL turtles signified recent recruitment to jetty habitat, most in this size class exhibited depleted delta13C and enriched delta15N values indicative of oceanic life. Reinforcing oceanic occupancy from stable isotope results was forage material dominated by oceanic items such as Sargassum spp., Scyphozoa spp., and plastic debris. Diet analysis of 25-34.9 cm SCL turtles implied regional differences existed in macroalgae and seagrass consumption. Enriched delta13C and delta15N values in newest scute suggest most turtles inhabited the jetty environment, where macroalgae is the most available forage. A definitive shift by >35 cm SCL turtles to inshore seagrass habitat was revealed by a diet of seagrasses and tissue enriched in delta13C and depleted in delta15N. This is the first study to integrate stomach contents of several green turtle size classes with tissue analysis of stable isotopes. The combination of these techniques provided an assessment of the effectiveness of stable isotope analyses in documenting diet and habitat shifts. Stomach content examination determined the most recent diet consumed within the habitat occupied, whereas stable isotope analysis provided a time-integrated synopsis of diet and habitat shifts. Findings indicate integration of stomach content and stable isotope analysis is highly effective for characterizing habitat use and foraging strategy of ontogenetic-stage green sea turtles.

Freshwater mussels are the most imperiled group of freshwater invertebrates globally. Recent research suggests a better understanding of mussel feeding ecology may facilitate and improve conservation efforts. The use of stable isotopes is becoming an increasingly common method to study aquatic food webs. Carbon (C) and nitrogen (N) are two of the most frequently employed elements in food web studies. Differences in natural abundance of 13C/12C can indicate which food sources are the basal sources of carbon incorporated into a consumer’s tissue, while the ratio of 15N /14N provides a method of assessing trophic position within a food web. Attached macroalgae, including the genus Cladophora, may be the dominant primary producers in running water systems. Cladophora, however, has not yet been indicated as a prominent assimilated food source for freshwater mussels. The overall purpose of this study was to assess if the diet of two common Green River mussel species, Amblema plicata (Say) and Elliptio dilatata (Rafinesque) were influenced by the seasonal change in availability of Cladophora during a summer-autumn rapid growth period. Two specific questions were asked: 1) Are the assimilated diets different between control and treatment areas, and 2) are the assimilated diets influenced by differing Cladophora levels across the study period? A mesocosm approach was employed in order to manipulate Cladophora levels within a treatment area. Seventy-two mussels, 36 each species, were sampled across four months,twice between control (= reach-scale, heavy Cladophora cover) and treatment (= localscale removal of Cladophora) areas. The freeware program, IsoSource, a concentration weighted linear mixing model, was used to determine the potential contribution of potential food sources to the diet of both mussel species. IsoSource revealed that Cladophora was the primary assimilated food source for both species across the study period. Although assimilated diets were not different between control and treatment areas, diets were, however, influenced by Cladophora availability across time. The results of this study indicate that, during bloom conditions, Cladophora is the primary carbon source for both A. plicata and E. dilatata and may form the base of food webs in the upper Green River.

Food webs are structured by intricate nodes of species interactions which govern the flow of organic matter in natural systems. Despite being long recognized as a key component in ecology, estimation of food web functioning is still challenging due to the difficulty in accurately measuring species interactions within a food web. Novel tracing methods that estimate species diet uptake and trophic position are therefore needed for assessing food web dynamics. The focus of this thesis is the use of compound specific nitrogen and carbon stable isotopes and molecular techniques for assessing predator-prey interactions and energy flow in natural aquatic ecosystems, with a particular focus on the species links between phytoplankton and zooplankton. The use of δ15N amino acid values to predict organism trophic position are evaluated through a meta-analysis of available literature which included measurements from 359 marine species (article I). Through a controlled feeding study isotope incorporation in aquatic organisms, across both plant-animal and animal-animal species linkages is further assessed (article II). These studies showed that δ15N amino acid values are useful tools for categorizing animal trophic position. Organism feeding ecology influenced nitrogen trophic discrimination (difference in isotope ratio between consumer and diet), with higher discrimination in herbivores compared to omnivores and carnivores (article I). Nitrogen isotope trophic discrimination also varied among feeding treatments in the laboratory study (article II). The combined findings from articles I &amp; II suggest that researchers should consider using group specific nitrogen trophic discrimination values to improve accuracy in species trophic position predictions.  Another key finding in the controlled laboratory study (article II) was consistently low carbon isotope discrimination in essential amino acids across all species linkages, confirming that these compounds are reliable dietary tracers. The δ13C ratios of essential amino acids were applied to study seasonal dynamics in zooplankton resource use in the Baltic Sea (article III). Data from this study indicated that zooplankton assimilate variable resources throughout the growing season. Molecular diet analysis (article IV) showed that marine copepod and cladoceran species ingested both autotrophic and heterotrophic resources. Evidence from both articles III &amp; IV also revealed that zooplankton feed on a relatively broad range of diet items but not opportunistically on all available food sources. Mesozooplankton feeding patterns suggested that energy and nutritional flows were channelled through an omnivorous zooplankton food web including microzooplankton prey items. Overall the results of this thesis highlight that stable isotope ratios in specific compounds and molecular techniques are useful tracing approaches that improve our understanding of food web functioning. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 4: Manuscript.</p><p> </p>

East Africa is central to many aspects of human evolution and diversification. At the same time, diet is a key aspect of the ecology of any population. Therefore, one is often interested in the diets of past populations. To assess human diet in the past, stable isotope ratio and dental microwear analyses are often perceived as the only semi-quantitative and objective techniques. However, there are still many unknowns on how isotopic and microwear signals change in response to dietary variation, because few controlled studies have been carried out in modern populations. To investigate this issue, this study targeted living humans from African ethnic groups (El Molo, Turkana, Luhya, and Luo, from Kenya, and Baka, from Cameroon) that practise a wide range of traditional subsistence strategies (pastoralism, fishing, and agriculture), with the objective of building a framework in which to consider past diet in an East African context. This study analysed human hair (n = 143), nail (n = 83), and breath (n = 186) for δ$^{13}$C and δ$^{15}$N from the six different communities, and dental moulds (n = 150) from five of those communities (no moulds were collected from the Baka), and related the findings to dietary information. Dental microwear analyses had a low success rate because microwear features were obscured by the biofilm produced by mouth bacteria. Nevertheless, a visual analysis of the results suggested that the El Molo have the hardest and the toughest diet among all the groups studied, possibly through the inclusion of abrasives in the diet during food processing. In turn, the isotopic analyses revealed the ways in which agriculturalists and hunter gatherers differ from pastoralists and fishers in their isotopic values, although the variation in δ$^{13}$C and δ$^{15}$N did not distinguish between pastoralists and fishers. The results emphasise recent changes in the diet of these groups, the importance of local factors in isotope values, and the variable sensitivity of isotopes to dietary practices. In conclusion, although each technique could provide complementary data that would contribute to a more inclusive view of diet, dental microwear analyses are not easily applied to modern human groups, due to the difficulty in acquiring comparative in vivo data, and in distinguishing between patterns caused by food items, or food processing techniques.

abstract: This dissertation focuses on the diversity inherent to the process of social community construction. Building upon previous archaeological and bioarchaeological studies of community identities, the current project emphasizes the need for consideration of the impact of diversity on community identity formation in the past and illustrates the utility of a bioarchaeological approach for undertaking this task. Three specific aspects of community formation are addressed: (1) the relationship between symbolic community boundaries and geographic space, (2) the influence of diverse discourses of intra-community sub-groups on community formation, and (3) the negotiation of community boundaries by outsiders. To investigate these aspects of community construction in the past, dietary practices and mortuary rituals of the Late Intermediate Period (c. AD 900-1470) Ychsma society of the central Peruvian coast are examined as a case study. Previous anthropological and sociological studies demonstrate that diet and burial customs are common mechanisms used in processes of group identification around the world, including the Andes. In the current study, analyses of materials from Armatambo and Rinconada Alta in the Rimac Valley are used to examine the ways in which isotopic and dental indicators of diet and archaeological contextual indicators of mortuary rituals correspond with or crosscut spatial burial patterns and additional groups based on sex, age at death, and biogeochemically reconstructed residential origins. Observed patterns are interpreted using a theoretical framework that incorporates sociocultural theory of identity with pre-Columbian Andean ideology of the body, self, and social environment. Results reveal differences in large-scale trends in diet and mortuary practices associated with burial at each site that are interpreted as evidence of symbolic community boundaries between sites. Complexities within larger trends reveal evidence of internal diversity as well as fluidity across community boundaries. Specifically, evidence is presented for intra-community dietary differences, intra-community differences associated with age and sex, and finally evidence of external relationships. This consideration of diversity in community identity construction is concluded to profoundly refine current understandings of Ychsma social interactions. Consequently, this study demonstrates empirical investigation of social diversity is necessary for understanding the complex nature of the social construction of communities in the past. / Dissertation/Thesis / Doctoral Dissertation Anthropology 2015

Fish can have complex life histories and use multiple habitats and resources throughout their life span. Consequently, their life histories are often poorly understood. The Atlantic Tarpon, Megalops atlanticus, is a large, typically migratory, elopomorph fish that is both ecologically and economically important. Atlantic Tarpon are under threat due to regional exploitation, loss of natal and juvenile habitat, poor water management, and offshore impacts. In addition, little is known about its lifelong habitat and resource use. In Chapter 1, I used stable isotope analysis of eye lens δ13C and δ15N values to explore patterns in trophic history and habitat use of 16 Atlantic Tarpon from West-Central Florida and Louisiana. The stable isotope chronologies showed 100% use of backcountry habitats during the early life history and an ontogenetic habitat shift to coastal waters at approximately 10 years of age and 140 cm total length. During the coastal phase Atlantic Tarpon displayed among-individual variability and within-individual consistency in basal resource use. In Chapter 2, mark-recapture data from a multi-year genetic tagging program were used to investigate survival and growth rates, ontogenetic habitat use, and migration of juvenile Atlantic Tarpon in Florida. The study found that juvenile Atlantic Tarpon take approximately 10 years to reach the length associated with maturity, and appear to have a high survival rate (~80%), possibly due to effective use of habitats with reduced competition and predation. Atlantic Tarpon underwent several ontogenetic habitat shifts throughout the juvenile phase. In addition, juvenile Atlantic Tarpon did not migrate long distances but instead showed fidelity to systems wherein only short movements were needed to shift habitat types. This work serves to fill critical gaps in our knowledge of Atlantic Tarpon life history and may aid in better management and conservation of the species.

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.

No description available.

Bats are important components of biodiversity within forested ecosystems. This research addressed habitat characteristics that influence species occupancy and stable isotopes and wing morphology to assess community structure within the Sam D. Hamilton Noxubee National Wildlife Refuge. To meet these objectives, I deployed echolocation recorders, mist-nets and conducted roost checks to capture bat acoustics; fur samples were also collected to measure ratios of carbon (C13/12) and nitrogen (N15/14). Relationships between occupancy, habitat class and features were not apparent for most species. However, Lasiurus and Mytois spp. showed positive relationships with proximity to roads, Lasiurus, positive with stem density and Perimyotis subflavus, negative with basal area. Stable isotope analysis revealed some distinction of trophic niches while wing morphometrics indicated bats of similar wing shape and size show greater trophic overlap. Collectively, these results suggest that habitat management, as current within the study area, will have limited influence on local bat distributions.

In 2001, 3269 unidentified individuals were found in a mass grave on the Northern part of Vilnius, Lithuania. Artifactual context indicates that these individuals were likely soldiers that were a part of Napoleon’s Grand Army. Stable oxygen isotope analysis was performed on bone apatite from 9 femoral bone samples to determine whether or not these individuals were Lithuanian locals and to test ratio variation. If individuals were foreigners, then geographical origins were approximated utilizing percentages of C4 plants from Holder (2013) and δ18O values that were extracted from bone apatite. The carbonate oxygen isotope compositions (δ18Ocarbonate) of bone apatite from the femoral samples (-4.4‰ to -6.2‰) indicate that these individuals were from central and western Europe (-4.0‰ to -6.9‰). It is significant that none of the individuals have values consistent with the area around Lithuania (-10.0‰ to -11.9‰), because it means that they all were non-local. It is also indicative that the Lithuanians were not burying their citizens in the grave and therefore strongly support that these individuals were Napoleonic soldiers. Additionally, although C4 percentages in the diet ranged from 17.8% to 31.7%, which overlaps with eastern European consumption patterns (approximately 15% to 25% of C4 plants) (Reitsema et al., 2010), the slight shift towards a higher C4 percentage is more representative of a central and western European diet. These results are significant because they provide stable isotopic evidence that these individuals were Napoleon’s soldiers whom participated in the Russian campaign of 1812.