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Beaudry, Frédéric. "Road Mortality Risk for Spotted and Blanding's Turtle Populations." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/BeaudryF2007.pdf.
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Saumure, Raymond A. "Growth, mutilation, and age structure of two populations of wood turtles, Clemmys insculpta, in southern Québec." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq29779.pdf.
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Marx, Melanie [Verfasser]. "Population connectivity of European Turtle Doves (Streptopelia turtur) : threats affecting European populations and modelling of species-habitat relationships at German breeding grounds / Melanie Marx." Gießen : Universitätsbibliothek, 2019. http://d-nb.info/1180979249/34.
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Wright, Lucy Isabel. "Insights into the mating systems of green turtle populations from molecular parentage analyses." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/3695.
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Gaining a good understanding of marine turtle mating systems is fundamental for their effective conservation, yet there are distinct gaps in our knowledge of their breeding ecology and life history, owing largely to the difficulty in observing these highly mobile animals at sea. Whilst multiple mating by females, or polyandry, has been documented in all marine turtle species, the fitness consequences of this behaviour have not been fully investigated. Furthermore, male mating patterns, operational sex ratios and the number of males contributing to breeding populations are poorly understood, impeding accurate assessments of population viability. In this thesis, I use molecular-based parentage analysis to study, in detail, the genetic mating system of two green turtle (Chelonia mydas) populations. In the focal population in northern Cyprus, I show that, despite exhibiting a strongly female-biased hatchling sex ratio and contrary to our expectations, there are at least 1.3 breeding males to every nesting female. I go on to assess the breeding frequency of male turtles in the population and determine that males do not breed annually at this site, demonstrating that the observed relatively equal sex ratio of breeders is not the result of a few males mating every year, but that the number of breeding males in the population is greater than expected. I show that 24% of nesting females in the population produce clutches with multiple paternity, but do not detect any fitness benefits to polyandrous females, and discuss the potential role of sexual conflict in influencing female mating decisions. Finally, I reveal a high frequency of multiple paternity in green turtle clutches on Ascension Island, one of the largest green turtle rookeries in the world, and discuss possible causes of variation in the level of polyandry among marine turtle populations. The results presented here shed new light on aspects of marine turtle mating systems that are challenging to study, and illustrate the value of molecular data, not only in describing mating patterns, but in elucidating aspects of life history and behaviour that would otherwise be very difficult to ascertain.
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Trembath, Dane F., and n/a. "The comparative ecology of Krefft's River Turtle Eydura krefftii in Tropical North Queensland." University of Canberra. Resource, Environmental & Heritage Sciences, 2005. http://erl.canberra.edu.au./public/adt-AUC20060711.113815.
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An ecological study was undertaken on four populations of Krefft�s River Turtle
Emydura krefftii inhabiting the Townsville Area of Tropical North Queensland. Two sites
were located in the Ross River, which runs through the urban areas of Townsville, and two
sites were in rural areas at Alligator Creek and Stuart Creek (known as the Townsville
Creeks). Earlier studies of the populations in Ross River had determined that the turtles
existed at an exceptionally high density, that is, they were superabundant, and so the
Townsville Creek sites were chosen as low abundance sites for comparison.
The first aim of this study was to determine if there had been any demographic
consequences caused by the abundance of turtle populations of the Ross River. Secondly, the
project aimed to determine if the impoundments in the Ross River had affected the freshwater
turtle fauna. Specifically this study aimed to determine if there were any difference between
the growth, size at maturity, sexual dimorphism, size distribution, and diet of Emydura krefftii
inhabiting two very different populations.
A mark-recapture program estimated the turtle population sizes at between 490 and
5350 turtles per hectare. Most populations exhibited a predominant female sex-bias over the
sampling period. Growth rates were rapid in juveniles but slowed once sexual maturity was
attained; in males, growth basically stopped at maturity, but in females, growth continued
post-maturity, although at a slower rate. Sexual maturity was at 6-7 years of age for males,
which corresponded to a carapace length of 150-160 mm, and 8-10 years of age for females,
which corresponded to a carapace length of 185-240 mm. The turtles were omnivorous,
although in the Ross River they ate more submerged vegetation (by percent amount and
occurrence) than those of the Townsville Creeks. Turtles in Townsville Creeks ingested more
windfall fruit and terrestrial insects.
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Trocini, Sabrina. "Health assessment and hatching success of two Western Australian loggerhead turtle (Caretta caretta) populations." Thesis, Trocini, Sabrina (2013) Health assessment and hatching success of two Western Australian loggerhead turtle (Caretta caretta) populations. PhD thesis, Murdoch University, 2013. https://researchrepository.murdoch.edu.au/id/eprint/18114/.
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Most of the existing sea turtle populations worldwide are in decline, and loggerhead turtles (Caretta caretta), in particular, are listed as Endangered. The loggerhead nesting population in Western Australia is the largest nesting population in Australia and one of the largest in the Indian Ocean and the world.
This research project investigated hatching success and health, two critical aspects for loggerhead turtle conservation and management, on two important nesting sites in Western Australia: Turtle Bay on Dirk Hartog Island and Bungelup Beach in Cape Range National Park. This project undertook an inter-disciplinary approach encompassing the disciplines of conservation medicine, ecology and epidemiology to investigate questions about sea turtle conservation that could not be addressed by any of these disciplines alone.
Morphological and reproductive measurements were collected during two nesting seasons, between 2006 and 2008, obtaining important baseline reproductive data about the Western Australian population. It was found that the presence of deformed and yolkless eggs was associated with smaller clutch size. At the same time several biotic and abiotic factors were assessed in relation to embryonic and hatchling mortality. Hatching success was significantly reduced by high temperatures during the pre-emergent period, the presence of roots in the nest and nest location along the beach. Results suggest that bacterial contamination of sand on the high nesting density beach sectors may, in part, be responsible for the differences in hatching success along the beach. High nest temperature during the pre-emergent period also significantly reduced emergence success and influenced emergence patterns and duration. Prolonged emergence duration, associated with increased nest temperatures, may further reduce hatchling survival due to diminished energy reserves and increased risk of predation.
On the mainland nesting site, Bungelup Beach, predation of eggs and hatchlings severely limited reproductive success with over 80% of the monitored nests showing signs of partial or complete predation. In contrast with that reported in the literature, ghost crabs (Ocypode spp) were the main predator at this site and the first among the identified predators to dig into nests. Perentie (Varanus giganteus) and introduced foxes (Vulpes vulpes) also predated on eggs and hatchlings, making the level of predation recorded unlikely to be sustainable in the long term.
Health monitoring of the nesting populations enabled the determination of baseline blood health parameters and toxin levels in blood. Two cases of fibropapillomatosis were confirmed for the first time in Western Australian loggerhead turtles. Changes in the leukogram and some biochemical parameters were detected in association with the presence of barnacles, in particular burrowing barnacles. In order to establish the connection between the nesting turtles’ health and reproductive success, maternal health indices were compared to hatching success and reproductive output. Several blood health parameters, including alpha and gamma proteins, iron, zinc and vitamin E levels, were correlated with hatching success or clutch size, suggesting that these parameters influence reproduction in loggerhead turtles. Additionally, sea turtles with reproductive abnormalities, such as soft-shelled or deformed eggs, had higher blood mercury levels than turtles without any egg or clutch abnormalities. This finding raises important questions about the toxic effect of mercury, at low blood concentrations, on sea turtle reproduction.
During the health assessment, a novel intraerythrocytic protozoal parasite species, similar to a malaria parasite (Haemoproteus and Plasmodium spp), was identified for the first time in sea turtles and was described through the use of light microscopy and diagnostic molecular techniques. The phylogenetic analysis indicated that this new parasite is closely related to other haemosporidia isolated from chelonians, but is well separated from malaria parasites isolated from other hosts (e.g. mammals, birds and other reptiles). This parasite appears to be largely benign. Although parasitaemia was low in all infected individuals, further studies are required to assess the potential impact of this haemoparasite on sea turtle fitness.
In conclusion, this study provided further understanding of factors affecting reproductive success, identified threats to the Western Australian nesting population whilst at the same time enabling assessment of the general health of nesting loggerhead turtles in Western Australia.
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Hatase, Hideo. "Studies on migration, dynamics, and genetic variation in Japanese loggerhead turtle (Caretta caretta) nesting populations." Kyoto University, 2002. http://hdl.handle.net/2433/149503.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第9778号
農博第1290号
新制||農||852(附属図書館)
学位論文||H14||N3709(農学部図書室)
UT51-2002-M156
京都大学大学院農学研究科応用生物科学専攻
(主査)教授 坂本 亘, 教授 田中 克, 教授 林 勇夫
学位規則第4条第1項該当
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Belleau, Pascale. "Habitat selection, movement patterns, and demography of common musk turtles (Sternotherus odoratus) in southwestern Québec." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112379.
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I studied the common musk turtle (Sternotherus odoratus) at the northern limit of its range at Norway Bay, Quebec, from April to October 2006. Common musk turtles are habitat specialists and are selective of their habitats at the study-area and home-range scales. Beaver ( Castor canadensis) lodges were preferred at the study-area scale. Common musk turtles also preferred beaver lodges, emergent wetlands, aquatic beds with floating and submerged vegetation as well as rocky shores at the home-range scale. At the location scale, common musk turtles chose shallower and cooler sites that contained more logs and submerged vegetation than the sites available at random. There was no significant effect of sex on habitat use at the location scale. There was no significant difference in mean daily movements between the sexes during the active season. However, sex and month probably interact together to influence the mean distance traveled daily by common musk turtles in Norway Bay. Males appeared to move more than females in May, July, and October. Females appeared to move more daily than males in August and September. Neither sex appeared to move more daily in June. However, our small sample size did not allow us to conduct a conclusive analysis. The mean home-range area was 23.9 ha and was not different between sexes. I estimated a density of 4.1 turtles/ha and a sex ratio of 1.7M: 1F. The population includes 59.6% males, 35.8% females, and 4.6% juveniles. Adults ranged from 77 mm to 133 mm in carapace length.
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Salvarani, Patricia Ishisaki. "Impact of contaminants in natural populations of marine turtles (Campeche, Mexico)." Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/23764.
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Doutoramento em BiologiaAs tartarugas marinhas sofrem um forte impacto populacional devido às atividades antropogênicas, como as causadas pelo aumento da exploração comercial e industrial nas áreas costeiras, alteração do habitat, ingestão de resíduos sólidos, captura acidental nas atividades pesqueiras e a contaminação de poluentes químicos. Das sete espécies de tartarugas marinhas existentes distribuídas por quase todos os oceanos (Caretta caretta, Chelonia mydas, Dermochelys coriacea, Eretmochelys imbricata, Lepidochelys olivacea, Natator depressus e Lepidochelys kempii), exceto o Natator depressus, todos os outros seis são listados como vulneráveis, em perigo ou criticamente ameaçado na lista da IUCN. Os contaminantes ambientais de origem química, como metais pesados, pesticidas, hidrocarbonetos, PCB, organoclorados e dioxinas estão causando um forte impacto na saúde de animais marinhos, incluindo tartarugas marinhas, e a bioacumulação desses poluentes em tecidos e órgãos influenciam o crescimento e desenvolvimento de populações naturais de tartarugas marinhas em todo o mundo, podendo causar mortalidade em vários estágios de seu desenvolvimento. Uma vez que estão em perigo é extremamente importante para a compreensão das respostas às medidas de impacto e conservação à longo prazo nas populações de tartarugas marinhas. Este trabalho é uma visão geral dos estudos sobre a quantificação de contaminantes em ovos e sangue de tartarugas marinhas, buscando relações entre o tamanho da carapaça e a atividade de enzimas antioxidantes usando técnicas não-letais. A concentração de pesticidas organoclorados (OCPs) no plasma das fêmeas adultas e os ovos das tartarugas de pente (Eretmochelys imbricata) e tartaruga verde (Chelonia mydas) que desovam na área costeira de Campeche serão analisados. O objetivo principal desta tese é avaliar o potencial das populações naturais como bioindicadores de contaminação química. Para tal, foram analisados os valores hematológicos, contaminação de OCPs no plasma e ovos de duas espécies de tartarugas marinhas com hábitos alimentares diferentes e uma possível transferência materna na espécie de tartaruga de pente. Por fim, a atividade de biomarcadores enzimáticos foram correlacionadas com a contaminação por OCPs. Os resultados mostraram que foram encontrados OCPs em todos os ovos analisados, mostrando maiores concentrações de ΣHCH e ΣDrines nas duas espécies selecionadas, sendo encontradas diferenças significativas entre as espécies e os anos analisados. Foram encontras diferenças significativas entre as concentrações de OCPs (ΣHCHs, ΣDrines e ΣChlordanes) em relação ao sangue e ovos, indicaram que esses contaminantes químicos estão sendo transferidos maternalmente. Nenhuma enzima antioxidante teve relação significativa com os OCPs mais encontrados no sangue (ΣDDTs, ΣHCHs e ΣDrines).
Sea turtles have been suffering strong population impact due to anthropogenic activities, such as those caused by the increase in commercial and industrial exploitation of coastal areas, habitat alteration, ingestion of solid waste, incidental capture in fishing activities and contamination of chemical pollutants. Of the seven species of marine turtles existing distributed by almost all oceans (Caretta caretta, Chelonia mydas, Dermochelys coriacea, Eretmochelys imbricata, Lepidochelys olivacea, Natator depressus and Lepidochelys kempii), except the Natator depressus, all other six are listed as vulnerable, endangered or critically endangered on the IUCN list. Environmental contaminants of chemical origin such as heavy metals, pesticides, hydrocarbons, PCBs, organochlorine, and dioxins are causing major health impacts of marine animals, including sea turtles, and bioaccumulation of these pollutants in tissues and organs influence the growth and development of natural populations of sea turtles worldwide, may cause mortality in various stages of development. Because they are endangered is extremely important to the understanding of responses to impact and conservation measures in the long term in the populations of sea turtles in developing. This work is an overview of studies on the quantification of contaminants in blood and sea turtle eggs, searching for relationships between, carapace size and the activity of antioxidant enzymes using non-lethal techniques. The concentration of organochlorine pesticides (OCPs) in plasma of adult females and eggs of hawksbill turtles (Eretmochelys imbricata) and green turtle (Chelonia mydas) that nest in the coastal area of Campeche will be analysed. The main objective of this thesis is to evaluate the potential of natural populations as bioindicators of chemical contamination. For this, the hematological values, contamination of OCPs in the plasma and eggs of two species of sea turtles with different feeding habits and a possible maternal transfer in the hawksbill turtles were analysed. Finally, the activity of enzymatic biomarkers was correlated with the contamination by OCPs. The results showed that OCPs were found in all analysed eggs, showing higher concentrations of ΣHCH and ΣDrines in the two species selected, being found significant differences between the species and the studied years. We find significant differences between the concentrations of OCPs (ΣHCHs, ΣDrines and ΣChlordanes) of blood to eggs showed that these chemical contaminants being transferred maternally. No antioxidant enzyme had significant relationship with COPs main found in the blood (ΣDDTs, ΣHCHs and ΣDrines).
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Hagood, Susan. "Genetic differentiation of selected Eastern box turtle (Terrapene carolina) populations in fragmented habitats, and a comparison of road-based mortality rates to population size." College Park, Md. : University of Maryland, 2009. http://hdl.handle.net/1903/9995.
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Thesis (Ph.D.) -- University of Maryland, College Park, 2009.Thesis research directed by: Marine, Estuarine, Environmental Sciences Graduate Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Portelinha, Thiago Costa Gonçalves. "Estrutura populacional e alometria reprodutiva de Podocnemis expansa (Testudines, Podocnemididae) no entorno do Parque Nacional do Araguaia, Tocantins." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/91/91131/tde-21062010-081308/.
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Dentre os répteis que ocorrem na Amazônia, os quelônios se destacam pela sua diversidade e importância econômica. Podocnemis expansa, conhecida popularmente como tartaruga-da-amazônia, é considerada o maior quelônio de água doce da América do Sul e tem sido explorada intensamente, por séculos, por inúmeras comunidades indígenas e ribeirinhas. O presente estudo teve como objetivo ampliar os conhecimentos acerca da ecologia populacional e da biologia reprodutiva de P. expansa no rio Javaés, Estado do Tocantins, no entorno do Parque Nacional do Araguaia (Ilha do Bananal). No primeiro capítulo desta dissertação foram investigados alguns aspectos da ecologia populacional. Os trabalhos em campo foram realizados entre os anos de 2004 e 2009 e os animais foram capturados pelos métodos de mergulho e arrasto de rede. Com os resultados obtidos, foi observado que a estrutura etária (baseada no comprimento da carapaça) dos indivíduos apresentou um padrão unimodal para os machos e um padrão não definido para as fêmeas. A população estudada era constituída basicamente por fêmeas jovens e machos adultos, apresentando uma razão sexual desviada para as fêmeas de 1:1,4 (:). A abundância relativa variou entre 0,4 e 8,6 animais/hora, dependendo do método de captura empregado, e a maioria dos animais (73,7%) encontrava-se concentrada em apenas um ponto específico do rio. No segundo capítulo, foram estudadas as relações alométricas entre o tamanho corpóreo da fêmea, seus rastros, as variáveis da ninhada e a forma dos ninhos em ambiente natural. O trabalho de campo foi realizado em uma praia de desova da área estudada, entre os meses de setembro e dezembro de 2008. Os resultados mostraram que o tamanho corpóreo da fêmea de P. expansa pode ser estimado em função do seu rastro, que fêmeas maiores deixam rastros maiores na areia, além de produzirem mais ovos (tamanho da ninhada) e com maior massa (massa da ninhada) do que fêmeas menores e que as variáveis largura da carapaça e massa da fêmea podem ser consideradas como confiáveis para estabelecer relações nos estudos de alometria com P. expansa.Among the reptiles found in the Amazon, the turtles stand out because of its diversity and economic importance. Podocnemis expansa, popularly known as Amazon river turtle, is considered the largest freshwater turtle in South America and has been heavily exploited for centuries by many indigenous and riverine communities. This study aimed to expand the knowledge about the population ecology and the reproductive biology of P. expansa in the Javaés River, Tocantins State, around the Parque Nacional do Araguaia (Iha do Bananal). In the first chapter of this dissertation some aspects of population ecology were investigated. Fieldwork was carried out between 2004 and 2009, and the animals were captured by diving and trawling net. The age structure (based on carapace length) of the animals showed a unimodal pattern for males and not a standard defined for females. The population consisted mainly of young females and adult males, with a sex ratio of 1:1.4 (:), biased to females. The relative abundance varied between 0.4 and 8.6 animals per hour depending on the method of capture employed, and most animals (73.7%) was concentrated in a single specific point of the river. In the second chapter, the allometric relationships between female body size, their tracks, the clutch variables and nest form in natural environment were investigated. Fieldwork was carried out on a nest beach of the study area, between September and December 2008. Results indicated that P. expansa female body size can be estimated based on her track. Larger females leave larger foot tracks in the sand and produce more eggs (clutch size) with greater mass (clutch mass) than smaller females. Female carapace width and female body mass can be regarded as reliable to establish relationships in studies of allometry with P. expansa.
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Le, Gal Anne-Sophie. "Réponses individuelles et démographiques de l'Emyde lépreuse (Mauremys leprosa) aux perturbations environnementales." Electronic Thesis or Diss., Perpignan, 2023. http://www.theses.fr/2023PERP0046.
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Les derniers rapports du Groupe d'experts intergouvernemental sur l'évolution du climat (GIEC) et de la Plateforme intergouvernementale scientifique et politique sur la biodiversité et les services écosystémiques (IPBES) alertent sur le déclin mondial de la biodiversité. Ce déclin est directement lié aux activités anthropiques, et en particulier à la destruction et aux pollutions des environnements terrestres et aquatiques. Les zones humides font partie des écosystèmes les plus menacés, avec une perte de 35% de leurs surfaces observée depuis 1970, et plus d'un quart des espèces résidentes menacées d'extinction. L'anthropisation contribue à la disparition de ces milieux, et à leur pollution chimique, notamment via les eaux usées, les rejets industriels, et le ruissellement agricole. Au sein de ces milieux, les espèces sentinelles peuvent être utilisées pour mesurer les effets des perturbations environnementales sur la biodiversité. Ces espèces sont résidentes du milieu étudié, longévives, et ont une réponse mesurable dans l'espace et dans le temps aux changements environnementaux. C'est le cas de l'Emyde lépreuse (Mauremys leprosa), une tortue dulçaquicole endémique des zones humides Méditerranéennes. De précédentes recherches ont montré que cette espèce bioaccumule des polluants et présente des réponses physiologiques contrastées en fonction du niveau de pollution de son habitat aquatique. L'objectif principal de cette thèse était d'identifier les réponses individuelles et démographiques de M. leprosa aux perturbations environnementales saisonnières et/ou induites par les pollutions anthropiques. Une approche intégrative combinant l'écotoxicologie, l'écologie des populations et l'écologie comportementale a été proposée pour répondre à cet objectif. La thèse pollemyde a permis de caractériser le fonctionnement des principales populations de M. leprosa en France, et de révéler les réponses de l'espèce aux perturbations environnementales. Les connaissances générées permettront d'adapter les mesures de conservation de l'espèce, dans le cadre du Plan National d'Actions actuellement en vigueur en FranceThe latest reports from the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) warn of the global decline in biodiversity. This decline is directly attributable to human activities, and in particular to the destruction and pollution of terrestrial and aquatic environments. Wetlands are among the most threatened ecosystems, with a 35% loss in surface area since 1970, and more than a quarter of resident species threatened with extinction. Anthropization contributes to the loss of these environments, and to their increasing chemical pollution, most notably from wastewater, industrial effluent, and agricultural runoff. Within these habitats, sentinel species can be used to assess the effects of environmental disturbances on biodiversity. Such species are resident, long-lived and exhibit measurable spatial and temporal response to environmental change. One example is the Mediterranean Pond Turtle (Mauremys leprosa), endemic of Mediterranean wetlands. Previous research has shown that this species can bioaccumulate pollutants and display contrasting physiological responses depending on the level of pollution in its aquatic habitat. This PhD thesis aimed to highlight the individual and demographic responses of M. leprosa to pollution-driven and seasonal environmental disturbances. An integrative approach combining ecotoxicology, population ecology and behavioral ecology has been used to meet the objectives of the thesis. This approach enabled us to characterize the functioning of three main populations of M. leprosa in France, and to highlight the responses of that species to environmental disturbances. The pollemyde thesis enhanced our knowledge of the ecology of M. leprosa and will serve to tailor conservation measures for the species, as part of the Plan National d'Actions now being implemented in France
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Griffin, Kathleen Ann Pletscher Daniel H. "Spatial population dynamics of western painted turtles in a wetland ecosystem in northwestern Montana." CONNECT TO THIS TITLE ONLINE, 2007. http://etd.lib.umt.edu/theses/available/etd-05272008-135912/.
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Thesis (Ph. D.)--University of Montana, 2007.Title from title screen. Description based on contents viewed Aug. 14, 2008. Includes 2 appendices: Potential effects of highway mortality and habitat fragmentation on a population of painted turtles in Montana, and Fencing methods and efficacy for minimizing turtle road kill and directing turtles to crossing structures, both by Kathy Griffin and Daniel H. Pletscher. Includes bibliographical references.
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Tomillo, Maria del Pilar Santidrián Spotila James R. "Factors affecting population dynamics of eastern pacific leatherback turtles (Dermochelys coriacea) /." Philadelphia, Pa. : Drexel University, 2007. http://hdl.handle.net/1860/2523.
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Bourjea, Jérôme. "Structure et connectivité de la mégafaune marine à l'échelle d’une région océanique : enjeux pour la gestion durable des tortues vertes dans l'océan Indien occidental." Thesis, La Réunion, 2014. http://www.theses.fr/2014LARE0015/document.
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Ce travail de thèse s'insère dans une démarche globale d'acquisition des connaissances sur la tortue verte (Chelonia mydas) dans l'océan Indien occidental et ce afin de disposer d'éléments scientifiques essentiels à la mise en place d'une gestion cohérente et efficace de cette espèce menacée. Dans un premier temps, appliquant différentes modèles statistiques, ce travail a visé à établir des données de référence sur l'abondance des tortues vertes femelles en reproduction et les tendances sur le long terme des principales populations. Dans un second temps, il a consisté à déterminer la structure génétique et les relations qui existent entre les différentes populations de cette espèce. Enfin, la conservation des tortues marines étant étroitement liée aux pressions extérieures, ce travail a tenté dans un troisième temps de caractériser les pressions anthropiques qu'elles subissent, et notamment celles liées à la pêche. L'ensemble de ces résultats a permis de réaliser des avancées majeures dans la connaissance de la biologie et de l'écologie de la tortue verte et de disposer d'une vision régionale fiable de l'état de conservation de cette espèce dans l'océan Indien occidental. Leur compilation a ainsi permis d'identifier des zones régionales prioritaires de protection mais aussi des sites de vigilance plus spécifiques comme celui d'Europa. Enfin cette synthèse met en lumière les priorités de recherche et les approches scientifiques à favoriser à l'avenir pour améliorer les connaissances et affiner les priorités de conservation non seulement des tortues marines, mais aussi de la mégafaune marine en généralThis thesis is a comprehensive work aiming to improve scientific knowledge on the green turtle (Chelonia mydas) in order to provide key scientific evidences needed for the implementation of coherent and effective management measures to protect at the Western Indian Ocean scale this threatened species. In a first step, this work aimed to established baseline data on the abundance of green turtles nesting females and long term trends of some key nesting populations of the region by applying different modelling methods. In a second step, this work determined the regional genetic structure of this species and the relationships that exists between the different populations. Finally, the conservation of marine turtles being closely dependant to external pressures, this work tried to characterize theanthropogenic pressures they face, more specifically those related to fishing activities. All these results allowed unraveling some key gaps on the biology and ecology of the green turtle in the region and led to a global vision of the conservation status of this species in the Western Indian Ocean. The compilation of the results enabled the identification of regional priority areas for protection, but also some more specific threatened sites such as Europa. Finally, this synthesis shedslight on research priorities and scientific approaches to be promote in the future to unlock other keyscientific issues and refine conservation priorities, not only of marine turtles, but also of marine megafauna as a whole
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Beau, Frédéric. "Ecologie de la Cistude d'Europe "Emys orbicularis" en Brenne : histoire de vie des nouveau-nés et influence des modes de gestion sur les populations." Thesis, La Rochelle, 2019. http://www.theses.fr/2019LAROS024.
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La Brenne est une région qui abrite aujourd’hui une biodiversité remarquable et de nombreuses espèces emblématiques des zones humides, parmi lesquelles la Cistude d’Europe Emys orbicularis occupe une place particulière. Cette espèce a été largement favorisée par les activités humaines passées. Les étangs, tous artificiels, ont vu s’installer et se développer depuis le Moyen Âge une des plus importantes populations de France. Cette espèce, dont la répartition française fut plus large, a subi d’importantes réductions essentiellement en raison des modifications des pratiques agricoles et l’utilisation, voire la disparition, des milieux aquatiques et terrestres nécessaires à son cycle de vie. Les Réserves naturelles sont des lieux de préservation du patrimoine naturel. La biologie de la conservation s’attache à proposer des mesures de préservation sur la base d’études scientifiques. Ce travail s’inscrit dans cette démarche sur une espèce pourtant déjà largement étudiée. Cette dernière considération nous a amené à porter nos recherches sur des éléments nouveaux pour l’espèce. Ainsi, nous avons souhaité tout d’abord étudier les facteurs liés aux sites de ponte : l’incubation in situ, les émergences et les premiers moments de vie des nouveau-nés qui quittent le nid. Puis, nous avons étudié les populations dans les étangs sous le prisme de la qualité des milieux aquatiques. Concernant notre premier objectif, jusqu’à présent les sites de ponte étaient considérés, et donc gérés, comme des lieux à optimiser pour la ponte des femelles. Or, il s’avère que l’utilisation de cet habitat terrestre par l’espèce va bien au-delà. En effet, la plasticité de la phénologie des émergences, liée à une faible mobilité des jeunes qui sortent du nid et leur utilisation du milieu, nous oblige à revoir nos considérations de gestion de ces habitats, tout du moins dans le contexte particulier (édaphique, climatique et météorologique) de la Brenne. L’étude des populations par la qualité des eaux nous apporte des premiers résultats, notamment sur la présence de mercure à des doses connues pour causer des troubles chez d’autres groupes d’espèces. L’origine de ce mercure ne semble pas imputable aux activités humaines locales, mais il semble issu du cycle global du mercure et une entrée dans la chaîne alimentaire liée à la gestion par les assecs réguliers. Sans avoir démontré d’impact sur la reproduction des cistudes, nous avons mis en évidence une corrélation qui incite à porter une attention à ce phénomène de présence de mercure dans les organismes vivants des étangs de Brenne. La présence d’algues sur les tortues aquatiques est connue depuis longtemps. Toutefois, nos résultats mettent en évidence une phénologie du recouvrement de la carapace différente selon les classes d’âge et les sexes. La modification des pratiques piscicoles, vers une intensification, apparait comme le facteur agissant sur la présence et la colonisation des cistudes par les algues, par une eutrophisation des milieux (étangs). De même que pour le mercure, bien que nous ayons mis en évidence des corrélations entre la couverture algale et la condition corporelle des femelles ou encore leur capacité de reproduction, ces premiers résultats sont à poursuivre afin de connaitre l’impact à long terme sur cette espèce longévive. En Brenne, les populations de cistudes sont encore importantes mais des variables telles que le taux de juvéniles dans les populations, la présence de mercure, le recouvrement parfois très important en algues, doivent nous inciter à maintenir notre vigilance pour cette espèce, et poursuivre le travail dans le cadre de la biologie de la conservation. Ceci accompagné de valorisations et de partages de ces connaissances et des expériences de gestion“Brenne” is a French wetland area which shelters a remarkable biodiversity and many emblematic species, among which the European pond turtle Emys orbicularis is particularly abundant. This species has been largely favored by past human activities. In Brenne, all ponds are man-made and have allowed the development, since the Middle Age, of one of the largest European pond turtle population in France. The distribution of this species has strongly decreased mainly because of changes in agricultural practices and the use of the aquatic and terrestrial environments necessary for its life cycle. Nature Reserves are important areas dedicated to the preservation of the natural heritage. One of the goal of biological conservation is to propose preservation measures based on scientific studies. E. orbicularis has been the subject of many of such studies. We choose to carry out our research on new elements for the species. First, we investigated parameters related to nesting sites: incubation under natural environment, emergence and postemergence behaviors of hatchlings. Second, we studied the populations under the prism of the quality of the aquatic environments. Generally, nesting sites were mainly considered as critical areas for egg-laying by females. However, it turns out that the use of this terrestrial habitat by the species is more important. Indeed, the plasticity of emergence phenology linked to a low mobility of hatchlings strongly suggest to change management practices of these habitats, at least in the particular context (edaphic, climate and weather) of Brenne. The study of the influence of water quality on populations allowed to highlight important patterns. Mercury levels in European pond turtle can reach doses known to cause disorders. The origin of this mercury does not seem to be linked to local human activities, but appears to originate from its global cycle. However, the Hg bioavailability is stimulated by local management practices, characterized by drainage periods. We have highlighted a correlation between the concentration of mercury and female reproduction (gravidity) which stimulates future research. A focus on algal epibiosis indicates that a large part of individuals are covered by algae. The presence of algae on aquatic turtles has been known for a long time. However, our results highlight differences of the algal epibiosis between ages and sexes. Intensive fish-farming appears to be responsible of the presence and prevalence of algae on turtles. Intensification of fish-farming practices causes an eutrophication of the environments. We also found correlations between algal cover and body condition and reproduction in adult females. These results should be pursued in order to know the long-term impact on this long-lived species. In Brenne, populations of European pond turtle are still large but some aspects such as proportion of juveniles, presence of mercury, or algal epibiosis deserve future studies in the field of conservation biology, with an emphasis on knowledge and management experiences sharing
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Stringell, Thomas Brian. "Population dynamics of marine turtles under harvest." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/14521.
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Understanding the ecology and life history of marine turtle populations is fundamental for their effective conservation, especially for those that are harvested for food. This thesis presents a collection of six chapters that progress from the applied to the pure; conservation and management in the first chapters through to animal ecology in the latter. A variety of contemporary and multidisciplinary techniques are utilised to explore the structure, populations dynamics and ecology of two marine turtle species, the green turtle (Chelonia mydas) and the hawksbill turtle (Eretmochelys imbricata), under harvest in the Turks and Caicos Islands (TCI), Caribbean. The work first focuses on the structure of TCI’s small-scale fishery and the demographics of turtles landed and incorporates nesting seasonality, adult take, satellite tracking and genetic structure to suggest evidence-based legislative amendments. As part of the study of this fishery, this work reports on how the harvest might increase prevalence of disease in green turtles. As an exploration into the ecology of turtle stocks found in TCI, the work then describes and compares in- water immature and adult sex ratios, genetic differentiation and sex biased dispersal. Finally, stomach content and habitat matching, and stable isotope analyses provide insights into the foraging ecology and suggested keystone roles of sympatric green and hawksbill turtles.
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Cuttriss, Andrew K. "Sea Turtle Ecology in the Gold Coast Region, Australia: Habitat Use, Nesting Behaviour and Movement Patterns." Thesis, Griffith University, 2014. http://hdl.handle.net/10072/365239.
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Habitat destruction and human exploitation has caused major declines in global sea turtle populations, resulting in six out of the seven species of sea turtles being classified as endangered or critically endangered by the International Union for the Conservation of Nature (IUCN). Extensive research has been undertaken on sea turtle nesting, breeding structure and abundance, migration and threats. However, little detailed information is available within the literature on sea turtle nesting behaviour, movement patterns and habitat usage within southern peripheral habitat limits of eastern Australia. This study investigates sea turtle ecology within the southern peripheral habitat limits on the east coast of Australia, Gold Coast region. The study focuses on the green, Chelonia mydas and loggerhead, Caretta caretta turtles, two species known to utilise the marine habitats of the Gold Coast Broadwater, South Stradbroke Island (SSI) and Cook Island (NSW) complex. The research quantified aspects of the nesting behaviour, movement patterns, habitat availability and usage, with a specific focus on the extensive seagrass meadows of the Gold Coast Broadwater. Seagrass habitats within the Broadwater were mapped in 2008 using aerial photography revealing that meadows cover 1208 ha within the Gold Coast Broadwater, an increase of 347 ha since 1987. Overall, 166 seagrass patches were mapped ranging in size from 0.25 ha to 124.4 ha with a mean size of 7.3 ± 15.9 ha. Despite the increase in the total seagrass extent, there was a significant decline in the mean patch size of seagrass meadows between 1987 and 2005. Despite the importance of seagrass meadows for turtles as foraging areas, the meadows in the Broadwater appeared to be poorly utilised by turtles.Thesis (Masters)
Master of Philosophy (MPhil)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Campbell, Cathi Lynn. "Population assessment and management needs of a green turtle, Chelonia mydas, population in the western Caribbean." [Gainesville, Fla.]: University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0000657.
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Edmonds, Jonathan H. "Population ecology of the stinkpot turtle (Sternotherus odoratus) in Georgian Bay, Ontario." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ35884.pdf.
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Hedges, Melissa Elizabeth. "Development and application of a multistate model to the northern subpopulation of loggerhead sea turtles." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/32185.
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Loggerhead sea turtles (Caretta caretta) are listed as threatened under the Endangered Species Act and are protected both on nesting beaches and in United States waters. Loggerhead sea turtles are long-lived species and are most easily studied on the beaches during the nesting season. Bald Head Island, North Carolina has one of the highest density nesting beaches of loggerhead sea turtles in the turtleâ s northern range on the East Coast of the United States. Key life history parameters were estimated and applied to a population model using 16 years of data from a mark-recapture study on the loggerhead sea turtle nesting population on Bald Head Island, North Carolina.
The beach survey conducted on the island only allowed for the capture of adult female sea turtles during the breeding state even though females may spend multiple years in the unobservable non-breeding state. The majority of females captured over the last 16 years have never been recaptured at the original capture site. These transients in the data coupled with unobservable states violate the assumption of equal catchability in the available single state mark-recapture models. Therefore, a multistate mark- recapture model originally developed for leatherback sea turtles was applied to the Bald Head Island loggerhead population. Multistate modeling provides a new technique to estimate sea turtle demographic parameters in which all model assumptions can be met. The multistate model outputs female survival rates, capture probability, and transition probabilities between breeding and non-breeding states. A correction factor for trap-dependence and transients was included given that both factors tested significant in the global model goodness-of-fit tests.
The estimates of annual adult survival rate and breeding transitions were then used to project population size for the northern subpopulation. For the first time, estimation error around estimates of benthic juvenile and adult survival rates was included in a loggerhead sea turtle model. I explored the effects of estimation error, three levels of clutch frequency, and larger TED openings on population growth rate and on the probability of reaching a nesting recovery threshold. The nesting recovery threshold was based upon recovery criteria from the Federal Recovery Plan and set as the probability of reaching 12,800 nests/season in the states of North Carolina, South Carolina, and Georgia within a 50 year time period. The results of this study provide important information to guide future management and research.Master of Science
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Breisch, Ariana N. "The natural history and thermal ecology of a population of spotted turtles (Clemmys guttata) and wood turtles (Glyptemys insculpta) in West Virginia." Huntington, WV : [Marshall University Libraries], 2006. http://www.marshall.edu/etd/descript.asp?ref=623.
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Theses (M.S.)--Marshall University, 2006.Title from document title page. Includes abstract. Document formatted into pages: contains xi, 319 p. including illustrations and maps. Bibliography: p. 228-234.
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Tortorelli, Brian Alfred. "Turtle Cam: Live Multimedia Interaction For Engaging Potential Visitor Population To Canaveral National Seashore." Master's thesis, University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5534.
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This project expands the outreach of the Canaveral National Seashore to its visitors, potential visitors, and virtual visitors through its goals in conservancy and preservation of its natural resources. This paper is involved with the current iteration of a series of digital media projects, the Sea Turtle Nest Camera, also known as, Turtle Cam. It details how and why this project was designed to be an ongoing initiative to assist in those goals.ID: 031001480; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Advisers: Cheryl Cabrera, Robb Lindgren, Robert Reedy.; Title from PDF title page (viewed July 16, 2013); Thesis (M.F.A.)--University of Central Florida, 2012.; Includes bibliographical references (p. 50-51).
M.F.A.
Masters
Visual Arts and Design
Arts and Humanities
Emerging Media; Digital Media
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Banger, Nicola A. "Consequences of Multiple Paternity for Female Fitness in an Ontario Population of Northern Map Turtles, 'Graptemys geographica'." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22881.
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Although sexual stereotypes paint males as being promiscuous and females as being choosy in order to increase their reproductive success, multiple mating by females is widespread and females of many taxa often produce progeny sired by multiple males – but why? In species in which there are no direct benefits associated with mating, females may adopt promiscuous mating strategies to increase their fitness through the acquisition of genetic benefits. Here, I examine the genetic mating system of map turtles, Graptemys geographica in Lake Opinicon. Based on the most conservative estimate, at least 71% of clutches in this population are sired by multiple males. There did not appear to be any relationship between female body size and frequency of multiple paternity. There was a marginally significant effect of multiple paternity on hatching success and survival of clutches, but there was no effect on hatchling morphology or locomotor performance.
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Nielsen, Janne Thoft. "Population Structure and the Mating System of Loggerhead Turtles (Caretta caretta)." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/507.
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Studies of the maternally inherited mitochondrial DNA in loggerhead sea turtles (Caretta caretta) demonstrate that females are philopatric, returning to nest in the region where they hatched. Eleven genetic stocks of maternal lineages have been identified in the Atlantic Ocean. An analysis of the conventionally-used 380 bp of the mitochondrial control region of a sample of individuals from the genetic stock of loggerheads in Mexico (N = 175) revealed 13 haplotypes. When a longer sequence read of 815 bp was analyzed, 17 haplotypes were uncovered. In the genetic stock of loggerheads in northwestern Florida (N = 25), three haplotypes were identified with both control region sequence lengths. Based on the currently known distributions of the three long CC-A1 and CC-A2 haplotypes, two of each are unique to Mexico. This makes the longer sequence reads useful for stock identification. Within Mexico, there was evidence of significant population structuring between Cozumel and the northern region of the sampling area on mainland Mexico (pairwise ϕST = 0.1003, p = 0.0197), but not after Bonferroni correction. A direct comparison of female and male nuclear microsatellite genotypes indicated male-biased dispersal between Mexico and northwestern Florida. Within Mexico, microsatellite analysis indicated significant structuring of females between sampling years and between the northern and the southern region of the sampling area on the mainland. Consequently, this genetic stock, while perhaps not in equilibrium, shows signs of female natal homing. An analysis of clutches indicated that significantly more clutches in Mexico had multiple paternity compared to the northwestern Florida (66% and 23%, respectively). The frequency of multiple paternity was not correlated with female abundance, nest density or sex ratio of reproductively successful individuals. There was no evidence of females benefiting through increased reproductive success from multiple paternity. This is consistent with other studies of sea turtles.
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Dillard, Kristin C. "A comparative analysis of geometric morphometrics across two Pseudemys turtle species in east central Virginia." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/4917.
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The phylogeny of the turtle genus Pseudemys is poorly understood. In Virginia, many turtles have been found with indicator traits of both eastern river cooters (Pseudemys concinna concinna) and northern red bellied cooters (Pseudemys rubriventris). This study explores morphological evidence for hybridization between the two species across three riverine sites in east central Virginia.
Museum voucher groups for each species were analyzed for relative shell height and plastron length. The shape of the plastral scutes and upper jaw were analyzed using landmark-based morphometric software. These metrics were compared with measurements taken from 188 field-caught Pseudemys specimens. Across phenotypic metrics, field specimens resembled northern red bellied cooters. Geometric morphometric analysis showed extreme variation. Thirteen field specimens exhibited indicator traits of both species. Because species boundaries do not appear to be well-resolved using accepted phenotypes and morphometrics, we suggest that additional research utilizing molecular methods and genetic analysis be conducted.
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Holden, Michael Thomas. "Assessing Changes in Bog Turtle (Glyptemys muhlenbergii) Population Abundance and Factors Influencing Nest Predation in Virginia." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/103775.
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Across the globe, wildlife populations are facing increasing challenges, with many taxonomic groups significantly declining. Among endangered vertebrates (including birds, non-avian reptiles, fishes, mammals, and amphibians), turtles are one of the most threatened groups with over 60% of the 356 recognized species classified as threatened or worse. Bog turtles (Glyptemys muhlenbergii), are among the most imperiled of North American freshwater turtles. These small, secretive turtles have declined by up to 90% in parts of their range, which consists of the Northern Population and the Southern Population, and spans the eastern U.S. from New York to Georgia. These declines are mainly documented in the northern part of their range, but recent work in North Carolina suggests that turtles in the southern part of their range are similarly declining. Prior to this research, surveys aimed at estimating abundance had not been conducted in Virginia since the late 1990's. The research described here was conducted as part of a state-wide population assessment of bog turtles in Virginia. For my first chapter, I conducted capture-mark-recapture surveys in six wetlands in Floyd County, Virginia during 2019 and 2020, and generated abundance estimates. These wetlands had been surveyed in the same manner in 1997, which provided me the opportunity to compare recent abundance estimates with those generated from the 1997 data. My analyses suggest that turtle abundance across these six sites has declined by approximately 50% since 1997. This decline appears to be driven by, but not wholly attributable to, the alteration and loss of habitat at 2-3 of the 6 sites.
Habitat loss is acknowledged as one of the major drivers of population declines throughout the range of the bog turtle, in addition to illegal collection for the international pet trade. Due to the life history traits of this species (long life span and low fecundity), the loss of an individual from any life stage from the population can have detrimental effects. While many turtle populations are not heavily impacted from periods of low reproductive success, numerous subsequent years of complete nesting failure can negatively impact population-level survival. Recent studies have suggested that anthropogenically subsidized nest predators may be playing a role in continued nest failure at certain wetlands. My second chapter investigated the factors associated with anthropogenic footprint (i.e., buildings) and infrastructure that may be driving nest predation by these subsidized predators. In 2019 and 2020, I conducted a field experiment in 35 wetlands which utilized artificial turtle nests to investigate variation in nest predation across Montgomery and Floyd Counties, Virginia. I found that increases in the percent of developed land-use and other metrics of anthropogenic disturbance significantly increased nest predation, while increases in the percent of land-use without roads or buildings significantly decreased nest predation.
The findings from these two chapters are consistent with population trends documented in other parts of the bog turtle range, and build upon prior studies to investigate drivers of nest predation. These results provide information that can be used by managers to aid in the conservation of this state endangered species, and suggest further courses of research for future projects.Master of Science
Across the globe, wildlife populations are facing increasing challenges, with many taxonomic groups significantly declining. Turtles are one of the most threatened groups of vertebrates with over 60% of the 356 species of turtle classified as threatened or endangered. Bog turtles (Glyptemys muhlenbergii), are among the most imperiled of North American freshwater turtles. These small, secretive turtles have declined by up to 90% in parts of their range, which consists of the Northern Population and the Southern Population, and spans the eastern U.S. from New York to Georgia. Prior to this research, no information on population trends was available for Virginia. To address this knowledge gap, I conducted surveys for bog turtles in six wetlands in Floyd County, Virginia during 2019 and 2020, and used the data from those surveys to estimate how many turtles were present in the wetlands. These wetlands had been surveyed in the same manner in 1997, which provided me the opportunity to compare recent estimates with those generated from the 1997 data. My analyses suggest that the total number of bog turtles present across these six sites has declined by approximately 50% since 1997. This decline appears to be caused at least in part by the alteration and loss of habitat at 2 of the 6 sites. Habitat loss is thought to be one of the major drivers of population declines throughout the range of the bog turtle, in addition to illegal collection for the international pet trade. Recent studies have suggested an additional problem, that anthropogenically subsidized nest predators may be playing a role in continued nest failure at certain wetlands. Animals such as raccoons, skunks, and bears can persist in greater numbers around human habitation, as we provide extra food sources such as garbage, bird feeders, deer feeders, etc. I investigated the factors associated with human infrastructure that may be driving nest predation by these subsidized predators. In 2019 and 2020, I conducted a field experiment in 35 wetlands using artificial turtle nests to investigate variation in nest predation across Montgomery and Floyd Counties, Virginia. I found that nest predation was significantly higher in areas with a higher percent of developed land-use. The findings from these two studies are consistent with population trends documented in other parts of the bog turtle range, and build upon prior studies to investigate drivers of nest predation. These results provide information that can be used by managers to aid in the conservation of this endangered species, and suggest further courses of research for future projects.
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Baggiano, Olivier. "The Murray - Darling Turtles: Gene Flow and Population Persistance in Dryland Rivers." Thesis, Griffith University, 2012. http://hdl.handle.net/10072/367471.
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Australia’s largest and most important waterway- the Murray-Darling Basin (MDB) - is under threat owing to predicted increases in temperature extremes and reduction in rainfall - runoff in the coming decades. Management strategies are required that incorporate an understanding of dispersal patterns of the MDB fauna and flora. Patterns of dispersal have typically been studied through direct organismal studies but genetic approaches, in which the movement of genes in the landscape is used as a correlate of species dispersal, can provide a more comprehensive view by investigating at a much larger temporal and spatial scale. Genetic connectivity (dispersal) is influenced by the biology of the species, and by flow regime and the dendritic pattern of the network in riverine landscapes. An understanding of the relative influence of each on connectivity is required to deliver informed management
strategies. Decisions regarding whether management for conservation is necessary also require an understanding of a species susceptibility to a changing environment. Species already exhibiting deleterious trajectories under current flow regimes in the basin may require more drastic measures than those that have remained unaffected.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Tiwari, Manjula. "Density-dependent effects on hatchling production in the green turtle nesting population in Tortuguero, Costa Rica." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0005620.
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Stephens, Sarah Holland. "Genetic analysis of the Kemp's ridley sea turtle (Lepidochelys kempii) and estimates of effective population size." Texas A&M University, 2003. http://hdl.handle.net/1969/220.
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Whitman, Elizabeth Rose. "Factors Affecting Green Turtle Foraging Ecology Across Multiple Spatial Scales." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3870.
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The hierarchical levels at which resource selection occurs can have important consequences for individual and population energy budgets and structure the impacts of a forager on its ecosystem. Assessing factors affecting resource selection of large marine herbivores across scales is important because of their potentially large impacts on seagrass community dynamics and historical and current changes in their population sizes and those of their potential predators. I explored the factors (predation risk, resource abundance, quality and identity) affecting resource use of large marine herbivores (green turtles, Chelonia mydas) from the scale of habitat patches to forage species within patches. I used a combination of in-water surveys, aerial drone video transects, baited camera surveys, and seagrass community and nutrient content analyses to provide insights into resource use by turtles in multiple ecological contexts.
In Abaco, The Bahamas I found relatively intact shark populations, including apex predators, relative to other parts of the Caribbean. In the context of healthy predator populations in Abaco, I tested a priori predictions rooted in Ideal Free Distribution (IFD) theory. Green turtles off Abaco deviated from predictions of an IFD determined by the standing stocks of seagrass. Instead, distributions are consistent with predictions of the foraging arena hypothesis with turtles largely restricted to safe habitat patches and selecting locations within these where seagrass N content is relatively high.
Marine invasive species can have detrimental effects on coastal ecosystems and economies. Therefore, understanding the effects of, and factors influencing the rate of spread of the invasive seagrass Halophila stipulacea in the Caribbean is important. In the French West Indies (Guadeloupe, Martinique and St. Martin), I investigated foraging preferences for native versus invasive seagrass species and whether green turtles might facilitate or attenuate the invasion through their choice of habitats and feeding patterns. Green turtle distributions were correlated with native seagrass distributions. Also, despite similar nutrient contents, turtles preferred feeding on native seagrasses irrespective of their relative abundance within a patch. These results suggest that, as predicted by the Enemy Release Hypothesis, green turtles likely facilitate the invasion and spread of the invasive seagrass that may reduce energy flow into turtle populations.
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Phillips, Katrina. "Beyond the Beach: Population Trends and Foraging Site Selection of a Florida Loggerhead Nesting Assemblage." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_theses/245.
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A twenty year mark-recapture dataset from the loggerhead nesting beach on Keewaydin Island, off the southwest coast of Florida, was analyzed using a two-state open robust design model in Program MARK to provide insight into recent nesting declines in the state. A total of 2,292 encounters representing 841 individual tag IDs were used for this analysis. Survival was estimated at 0.73 (95% CI 0.69-0.76), and there was no evidence from remigration rate or clutch frequency to suggest the composition of the nesting assemblage had changed over time. The mark-recapture analysis was supplemented with a satellite tracking component to identify the offshore foraging areas utilized by Keewaydin nesters. Eleven nesting females were outfitted with platform terminal transmitters, which transmitted for 42 to 300+ days including inter-nesting intervals and subsequent migration to foraging grounds. Site fidelity tests and kernel density home range analyses were used to describe foraging habitats. Females foraging in the eastern Gulf of Mexico were within the recent 64 m bottom longline fishery restriction. Areas identified as important habitats during the remigration interval should be used to inform managers in creating targeted management strategies to aid population recovery without the use of broad fishery closures.
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Douglas, Donna Nabeha Carleton University Dissertation Chemistry. "Anoxia induces changes in translatable mRNA populations in Trachemys scripta elegans: a possible adaptive strategy for anoxia tolerance." Ottawa, 1993.
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Standing, Katherine Lorraine. "Reproduction, nest site selection, and neonatal behaviour in a northern peripheral population of Blanding's turtle, Emydoidea blandingii." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq23702.pdf.
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Stokes, Kimberley Laura. "Ecology of marine turtles under climate change." Thesis, University of Exeter, 2014. http://hdl.handle.net/10871/21847.
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Climate change threatens to disrupt biological systems around the globe, sparking debate over natural capacity for adaptation in a fragmented landscape. Marine turtles are evolutionarily ancient and have survived millions of years of prehistoric climate change, but are threatened by the rapidity of modern warming and a history of severe overexploitation that has left most populations depleted. This thesis explores a nesting aggregation of the green turtle (Chelonia mydas) in northern Cyprus, where a longitudinal programme of both intensive and extensive monitoring enables insight into individual and population level parameters and processes. Nesting on the two coastlines covered by this project is in the early stages of recovery, possibly in response to exhaustive nest protection efforts over the last twenty years. Saturation tagging at one key site allows us to confirm that recruitment of new breeders is an important driver of this trend, and that average clutch frequency has remained stable around three nests per female per year, validating nest-count derived abundance estimates at a regional scale. Concern has been raised, however, regarding recent changes in fishing practices which are impacting the local juvenile neritic phase, which may have a lagged effect on the recovery of this nesting population. A collaborative tracking effort including all other countries with major nesting in the Mediterranean allows us to identify major foraging grounds for this species, with two hotspots accounting for >50% of tracked individuals, as well as coastal and pelagic seasonal corridors of high use. Bycatch levels and mortality rates for turtles in these key areas are largely unknown and should be prioritised for investigation. Hatchling sex ratios from the main study beach are extremely female-biased (estimated 97% female for the twenty year period 1993-2012). A 1oC rise in average incubation temperatures threatens near complete hatchling feminisation on this beach, whilst a 2oC rise could reduce hatch success to less than 50%. Thermal effects on hatchling morphometrics are evident, with a 1oC rise in temperature reducing average length, width and weight by 1%, 2% and 3% respectively. More favourable incubation conditions were found early in the season, in deeper nests laid by larger females, and on beaches of lighter sand. In contrast, adult sex ratios at the main site are male-biased, posing questions regarding sex-specific survival rates and optimal hatchling sex ratios. A phenological shift towards earlier nesting is demonstrated for the first time in this species, and could potentially ameliorate warming effects. Carry-over climate forcing effects from the foraging ground influence the breeding frequency of individuals, driving population level responses in annual magnitude of nesting. This work emphasises the utility and necessity of long-term individual-based monitoring programmes in elucidating population trends and climate responses in iteroparous species with non-annual breeding.
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Barbanti, Anna. "Sea turtle conservation: genetics and genomics for a better management." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/672159.
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Conservation actions aim to preserve and recover animal and plant species using in-situ or ex- situ strategies. The first, aims to protect and sustain populations in their natural habitat, the second are implemented when local populations are extinct or are about to be. Conservation genetics can provide important insights into the dynamics of endangered populations facilitating their management.
This thesis uses traditional markers and new generation sequencing to improve conservation management of the loggerhead (Caretta caretta) and the green turtle (Chelonia mydas). In the first 2 chapters we used microsatellites and mtDNA to assess the outcome of a reintroduction program of green turtles in the Cayman Islands and the status of the reintroduced wild population. We found that 90% of adult wild females and 80% of wild F1 hatchlings were related to the captive population, proving the program successful. This relatedness did affect negatively the fitness of the wild population. Moreover, we found that after only one generation, genetic differentiation between the populations was significant. Our results suggest that assisted colonisation is a viable solution to the global decline of biodiversity. The third chapter explores the potential of 2b-RAD methodology in the field of non-model species population genomics and provides guidelines to optimise protocol and decision making using 2b-RAD. We discovered that, given the big genome size of the loggerhead turtle, a selective-base ligation should be used to obtain an overall depth of coverage of 20x and make the study cost-effective. The fourth chapter studies the population structure and local adaptation of 9 Eastern Mediterranean loggerhead turtle rookeries using 2b- RAD genomic sequencing. We found a high level of population structure and no overlapping among rookeries. Bayesian clustering indicated our individuals to be grouped in nine genetic clusters, which correspond to the distribution found in the PCoA. We found that atmospheric temperature and geographic location of the rookery have a significant impact on population structure, as outlier loci were found associated with these predictors. These results aim to use fine scale genetic information of the Eastern Mediterranean Sea to inform and improve conservation management of loggerhead turtle rookeries.
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Bradshaw, Philip James. "Investigating variation in the life-history strategy of marine turtles." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/28998.
Full textAbstract:
Understanding the degree of connectivity among populations, forming migratory links and evaluating factors that influence reproductive fitness is fundamental for the successful management of migratory species of conservation concern. In this thesis I focus on a regionally important rookery of green turtles (Chelonia mydas) at Alagadi beach in northern Cyprus that has been intensively studied since 1992. I employ high resolution genetic markers with different modes of inheritance to reveal fine scale population structuring among four rookeries within a 200 km stretch of shoreline. The relative importance of four foraging areas and the annual contribution from each site to the breeding cohort are evaluated using the stable isotope ratios of the turtles calibrated by satellite telemetry. The stable isotope ratios of the turtles reveal that a previous undisclosed foraging site at Lake Bardawil in Egypt is critical for the population recovery of the Alagadi rookery. The temporal consistency of stable isotope ratios reaffirm that green turtles exhibit high fidelity to foraging sites allowing the evaluation of foraging area effects on reproductive traits to be evaluated over multiple seasons. I investigate the population sub-structuring of the Alagadi nesting aggregation grouped by the foraging area used. The absence of genetic structure supported the Learning Migration Goal Theory and provided evidence that the significant among site phenotypic variability in the body size of recruits, the length of interbreeding intervals and the date that the first nest of the season was made is a result of foraging areas effects. No significant among site phenotypic variability was found for the size or number of clutches laid. Among site variability in interbreeding intervals resulted in substantial variation in the reproductive potential of individuals due to assumed differences in resource availability and environmental factors. The multilocus genotypes generated for 243 nesting females were employed to reconstruct the first wild marine turtle pedigree using a full-likelihood sib-ship reconstruction approach. This revealed that the effective contribution to the next generation was unequal and allowed a minimum age to maturity to be estimated from parent – offspring assignations. However, sample size constraints prevented accurate estimates for the narrow-sense heritability of the five morphological and life-history traits from the quantitative genetic analysis. The multifaceted approach taken here to unravel the cryptic life-history of marine turtles emphasises the importance of long-term individual-based monitoring and the data generated can be employed to advise conservation strategy for this critically endangered regional management unit.
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Harms, Hillary Morgan. "Conservation of the Spotted Turtle (Clemmys guttata): Identifying Critical Demographic and Environmental Constraints Affecting Viability." Bowling Green State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1213634295.
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Seney, Erin Elizabeth. "Population dynamics and movements of the Kemp's ridley sea turtle, lepidochelys kempii, in the northwestern Gulf of Mexico." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2375.
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King, Cheryl S. "An Assessment of Sea Turtle Relative Abundance, Distribution, Habitat, and Population Characteristics Within the Kaho'olawe Island Reserve, Hawai'i." NSUWorks, 2007. http://nsuworks.nova.edu/occ_stuetd/113.
Full textAbstract:
e sea turtle population utilizing habitats within the Kaho‘olawe Island Reserve (KIR) has gone practically unstudied. This baseline assessment (2002-2005) used a combination of aerial and in-water research methodologies designed in conjunction with recording all incidental sightings and opportunistic reports. In addition, cultural insight, previous studies, literature, and other references were reviewed totaling 708 sightings that provided the subsequent information on the occurrence of turtles within the reserve.
Overall, the different research assessment techniques produced similar results, suggesting the validity of the observations. All techniques had their separate merits and played significant roles due to the restrictions imposed on operations within a former military bombing range and the ongoing research activities of the Kaho‘olawe Island Reserve Commission (KIRC) Ocean Resources Management Program. The most superior methodology was the aerial survey for island-wide relative abundances and distributions, but in-water surveys were valuable in assessing turtle population characteristics, especially the fibropapilloma rate and site fidelity. Coastal surveys were done to search for signs of nesting or basking, but none were documented.
This study found turtles most commonly swimming individually in clear, shallow water (1-6m depth) coral reef habitats 5-20m from shore. Besides one female hawksbill (Eretmochelys imbricata), all were greens (Chelonia mydas) with no evidence of fibropapillomatosis. Immature turtles predominated and were fairly evenly distributed with some areas of higher density around Kaho‘olawe, namely in the Kākā, Hakioawa and Kealaikahiki regions. Using photo-identification techniques, the strongest example of site fidelity was one particular turtle being resighted three times in the same location, with an 815-day interval between the first and last sighting. It was most common to find the turtles swimming as opposed to resting or foraging. The twenty foraging observations that were made occurred primarily in the Hakioawa and Kākā regions (depth mean=6m, SD=3.8m, range 1-11m). All were seen foraging on turf algae, as the abundance of macroalgae within the KIR was limited.
General turtle reactions to our presence were quantified roughly. With humans in the water the majority of the turtles kept a safe distance while exhibiting a slow departure from humans; unless approached closer (by free-diving) which typically caused them to flee. Near equal percentages exhibited flight responses versus toleration of our presence. Only one turtle displayed flipper swiping. During aerial surveys, our helicopter flew at ~31m which did not appear to alter turtle behavior as much as expected. As was the case of turtle reactions to our vessel Hākilo, disturbance was difficult to quantify unambiguously. Some turtles dove abruptly and others appeared to be unaffected by our presence, likely due to other variables unknown to us.
Abundance estimates were negatively biased due to availability biases (submerged turtles) and our detection limitations of naturally camouflaged, highly alert animals. Twenty-nine standardized aerial surveys averaged 7.2 turtles (SD=3.4, range 1-14, n=209) per ~60-minute circumnavigation survey yielding a mean density of 0.153 turtles per km (0.248/mile). Nineteen north coast surveys averaged 2.3 turtles (SD=1.76, range 0-6, n=43) per ~20 minute survey, resulting in a mean density of 0.131 turtles per km (0.209/mile). Sixty-seven nearly island-wide snorkel transects yielded a 1.31 turtles/hr mean (transect SD=1.8, range 0-8, n=82). Although effort varied widely, it was most common to incidentally witness one turtle at the surface per (~5-hour) day while different research activities within the reserve were conducted (1.29/day mean, SD=1.26, range 0-6, n=76 field days, n=98 turtles).
Exploratory analyses of correction factors for submerged turtles during aerial surveys and the collation of all sightings and references roughly estimate that fewer than 500 turtles inhabit the KIR (although these results should be used cautiously). KIR-specific turtle diving behaviors must be determined to enable reliable correction factors to be applied to density abundance estimates. Although these research results are not directly comparable to other studies within the rest of the Main Hawaiian Islands because this is the first island-wide study, these low numbers suggest a rather insignificant contribution to the extant population of Hawaiian sea turtles.
This baseline estimate allows for a) future comparisons using these standardized monitoring protocols, and b) the prioritization of restrictions to important KIR habitats, with implications for management on other islands. As the restoration and management of the KIR continues successfully, this reserve has great potential to host a healthy population of sea turtles that would be able to thrive in a non-anthropogenically stressed environment. Therefore this population and nearshore habitat should continue to be monitored and protected.
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Schwartz, Tonia S. "Population Structure of the Gopher Tortise (Gopherus polyphemus) in Florida, using Microsatellites." Scholar Commons, 2003. https://scholarcommons.usf.edu/etd/1471.
Full textAbstract:
Gopher tortoise (Gopherus polyphemus) population sizes have drastically declined in the past 100 years. Much of this decline has been attributed to past human predation, to habitat loss from human development, and potentially to the recently discovered upper respiratory tract disease. An understanding of the genetic structure among populations is critical for the long-term success of relocation and other management strategies. This research focuses on the development of a suite of genetic markers and the answers they provided to questions concerning present day population genetics and its use in management. In addition, this study provides inference on historical refugia and dispersal patterns of the gopher tortoise through the Pleistocene.
Nine microsatellite loci were identified, optimized, and characterized from a G. polyphemus microsatellite-enriched DNA library. These loci are applicable for population level analysis along with parentage analysis in all Gopherus species. In addition, a few of the loci also work in other Testudinies. Application of these markers to eighteen Florida and two Georgia populations of gopher tortoises reveal considerable amount of genetic diversity within the species and substantial genetic subdivision among populations, especially in the northern part of the Florida peninsula and southern Georgia. Admixture and genetic homogenization in central Florida may be attributed to past human mitigation events as much of this area has been substantially developed. These data indicate a more conservative approach to relocation is necessary if the goal is to maintain the genetic distinctiveness of these areas.
Lastly, these genetic data, in conjunction with historical geological, climactic, and fossil records, were used to identify gopher tortoise refugia, and dispersal patterns during the Pleistocene. Within Florida, four major genetic assemblages were determined that correspond to four Pleistocene ridges that would have been present at high sea levels: Lake Wales Ridge, Brooksville Ridge, Southern Atlantic Coastal Ridge, and Mt. Dora Ridge. In addition, these data indicate that tortoises that dispersed into southeastern Florida after the fall in sea level were most closely related to tortoises from the Brooksville Ridge. Likewise, tortoises in northwestern Florida and southern Georgia were most closely related to tortoises from the Mt. Dora Ridge.
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Spencer, Ricky-John. "The Murray River Turtle, Emydura macquarii: Population Dynamics, Nesting Ecology and Impact of the Introduced Red Fox, Vulpes vulpes." University of Sydney. Biological Sciences, 2001. http://hdl.handle.net/2123/373.
Full textAbstract:
I studied aspects of the ecology of the Murray River turtle, Emydura macquarii, to determine the impact of the introduced red fox, Vulpes vulpes. The fox is one of Australia's worst vertebrate pests through its predation on livestock and native mammals, but their impact on reptilian communities is not known. I conducted a large-scale mark-recapture study to evaluate population growth of E. macquarii in the Albury region of the upper Murray River by determining growth, reproduction and survival. The study was conducted downstream of the first, and largest, impoundment on the Murray River, Lake Hume. Emydura macquarii predominantly inhabit the lagoons in the upper Murray River, as the mainstream and Lake are possibly too cool to maintain metabolic processes. They are easily captured in hoop traps and the use of live decoys maximises trap success. Over 2000 hatchling turtles were marked and released into two lagoons between January 1997 and January 1998. Growth of these individuals is rapid over the first few years but declines towards maturity, and is indeterminate after maturity. Although growth annuli are not well defined, even on young individuals, the von Bertalanffy model describes the growth of both male and female E. macquarii. Male turtles mature at 5-6 years and females mature at 10-12 years. Female turtles may maximise reproductive potential by delaying maturity and producing one relatively large clutch (mean = 21 eggs) per year, which is positively correlated with body size (PL). Although primarily related to body size, clutch size varies annually because of environmental conditions. If winter and summer rainfalls are below average and temperatures are above average, E. macquarii may reduce clutch size to increase the chance of the eggs surviving. Nesting predominantly occurs during the first major rain-bearing depression in November. Habitat variables, including distance from water, nearest nest, and tree, and soil type were measured for each nest to determine characteristics that attract predators. Nests close to the shoreline and trees are heavily preyed on, and nests constructed in sand are less likely to be destroyed by predators. Foxes detect nests through a combination of chemical cues from eggs and slight soil disturbances, whereas birds only destroy nests observed being constructed during the day. Female turtles alter nesting behaviour and construct nests much further away from water when foxes were removed and as a result, nests are less dense and away from trees. Thus in high predation risk areas, turtles minimise emergence and search times to reduce the risk of direct predation by foxes. Predation is reduced when nests are in lower densities and away from trees, because predators increase search efforts when nests are in higher densities and birds are more likely to destroy nests close to trees. Reproductive success is further reduced in high predation risk areas because more nests are constructed in sandy substrates where clutch success is reduced compared to incubation in more dense substrates. Where predators are a significant source of mortality, prey may use indirect methods, such as chemical recognition, to avoid encounters. Nesting turtles did not avoid areas where fox odour was present, suggesting that they assess predation pressure from foxes by other mechanisms, such as visual recognition. However, an innate response occurs to the odour of a once common predator on the Murray River, the eastern quoll (Dasyurus viverrinus), whereby turtles recognise and avoid nesting in areas where quoll odour is present. Therefore nesting turtles show a similar avoidance response to two different predators, using different mechanisms of detection. Similarly, predation risk may influence hatching times and nest emergence. The rate of embryonic development of E. macquarii may increase or eggs may hatch early so that the clutch hatches synchronously, thereby reducing the risk of predation through group emergence from the nest. Emydura macquarii reach densities of over 100 turtles.ha-1, with the majority of the population consisting of sexually mature individuals. Emydura macquarii has a Type III survival curve where mortality is extremely high in the egg stage (93% nest predation), remaining high over the hatchling stage (minimum survival rate- 10%), but decreasing rapidly throughout the juvenile stage (~70% juvenile survival). Adult survival is extremely high, with greater than 95% of adults surviving each year. Foxes through nest predation cause most mortality but a small proportion (~3%) of nesting adult females are killed by foxes each year. A removal program evaluated the impact of foxes. In 1996, fox numbers were monitored around four lagoons by spotlighting and non-toxic bait uptake. Foxes were removed from around two of the lagoons throughout 1997 and 1998, using spotlight shooting and 1080 bait poisoning. Fox numbers were continually monitored around all four lagoons during the study. Nest predation rates remained around 90% in all sites where foxes were present, but fell to less than 50% when foxes were removed. At the same time, predation on nesting female turtles was eliminated where foxes were removed. Demographic models using staged based survival schedules, together with growth and fecundity values for E. macquarii show a decline of 4% per year in these populations. Elasticity analyses shows that survival of adult female E. macquarii has the major influence on population stability and a reduction of nest predation alone is unlikely to address the population decline. Management options, such as reducing foxes prior to nesting around key lagoons, will stabilise the population decline, and eliminating foxes completely from certain areas with high dispersal potential, will promote recruitment of juvenile E. macquarii.
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Spencer, Ricky-John. "The Murray River turtle, Emydura macquarii population dynamics, nesting ecology and impact of the introduced red fox, Vulpes vulpes /." Connect to full text, 2000. http://hdl.handle.net/2123/373.
Full textAbstract:
Thesis (Ph. D.)--University of Sydney, 2001.Includes tables. Title from title screen (viewed Apr. 22, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Biological Sciences, Faculty of Science. Degree awarded 2001; thesis submitted 2000. Includes bibliography. Also available in print form.
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Dalem, Anak Agung Gde Raka, University of Western Sydney, and Faculty of Science and Technology. "Demography and movement patterns of a population of eastern snake-necked turtles, Chelodina longicollis (Shaw, 1794)." THESIS_FST_xxx_Dalem_A.xml, 1998. http://handle.uws.edu.au:8081/1959.7/63.
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With 226-343 individual/ha, population density of Chelodina longicollis in the dams of the University of Western Sydney-Hawkesbury Richmond campus were in the range of other studies around Australia. Their size extremes (24.3 -223.3 mm) were within the range of previous studies, and the overall sex ratio was skewed toward males. The annual growth rates varied and were weakly correlated with animal size. Scute shedding occurred between September and April and peaked in December. Turtles were generally in excellent condition, indicating that sufficient food resources were available in local habitats. Only 3.4% of the population were in poor condition and few animals (8.8 %) carried signs of past injury. No gross abnormalities were recorded, however, there has been low levels of recruitment to the population compared with other Australian studies. Despite a maximum distance dams sampled of 2.8 km and ample evidence of interchange between dams, there was a great variation in animal size, cohort structure, sex ratio among dams. There are a range of factors which have the potential to bias sampling results. Turtles were not influenced by a dominance hierarchy or by the presence of eels, however, they appeared to be capable of avoidance behaviour when nets are set at a specific location. Different cohorts were caught differentially and this varied with month, season and year. In addition, catchability varied among cohorts. Juveniles were least likely, and sub-adult males were most likely, to be recaptured. In some dams there was evidence that animals moved at random while in others movement did not conform to this pattern. These results could not be accounted for in terms of dam size, physical structure of the dam or the distribution and abundance of vegetation.Master of Science (Hons)
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Rodrigues, JoÃo FabrÃcio Mota. "How the freshwater turtles survive and reproduce in caatinga? - Life history traits of Phrynops tuberosus (Testudines: Chelidae)." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=9486.
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The life history theory studies the characteristics combinations that maximize the organisms reproduction and survival in the environment where they live. The species
use the habitat in a diverse way and this use depends on the environmental conditions in the available habitats. Phrynops tuberosus, a freshwater turtle found in the north-northeastern regions of Brazil, is the animal-model chosen for the life history traits and habitat use studies. This work aims understand how this species reproduce, maintain and use the habitat in Caatinga. The study generated biological and ecological knowledge of the species and allowed the testing of hypotheses and predictions of life history traits, sexual dimorphism and habitat use. Selection of clutching sites, males smaller than females and preference of larger animals for environments most exposed were found in the populations studied. The results facilitate understanding of reproduction and survival of turtles in a semiarid environment.A teoria de histÃria de vida estuda as combinaÃÃes de caracterÃsticas que maximizam a reproduÃÃo e a sobrevivÃncia dos organismos no ambiente onde vivem. As espÃcies utilizam o ambiente de modo diverso, e esse uso depende das condiÃÃes existentes nos hÃbitats disponÃveis. Phrynops tuberosus, cÃgado encontrado nas regiÃes norte-nordeste do Brasil, Ã o animal-modelo escolhido para o estudo dos traÃos de histÃria de vida e de uso de hÃbitat. Esse trabalho objetiva entender como a espÃcie se reproduz, organiza-se e utiliza o hÃbitat na caatinga. O estudo gerou conhecimentos biolÃgicos e ecolÃgicos da espÃcie e permitiu o teste de hipÃteses e previsÃes sobre traÃos de histÃria de vida, dimorfismo sexual e uso de hÃbitat. SeleÃÃo de locais de desova, machos menores que fÃmeas e preferÃncia de animais maiores por ambientes mais expostos foram encontradas nas populaÃÃes estudadas. Os resultados encontrados facilitam a compreensÃo da reproduÃÃo e da sobrevivÃncia dos quelÃnios em um ambiente do semiÃrido.
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Miller, Veronica A. "Selected Demography and Population Estimation of Trachemys scripta (Yellow-bellied Slider) in North Carolina as it Relates to Turtle Harvesting." NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-05102006-094922/.
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In the year 2000, a reported 460 turtles were removed from North Carolina for commercial use. In 2002, the reported take of turtles soared to a staggering 23,311 turtles. A continuation of this trend could severely deplete the turtle populations of North Carolina in a short time. Therefore a moratorium on commercial turtle harvesting was instituted by the North Carolina General Assembly on July 1, 2003, effective until the NC Wildlife Resources Commission could determine rules and regulations for harvesting. It is crucial to know the level of harvest that populations can sustain, and, if a population is harvestable, which age groups are most sensitive to harvest. Regulations on reporting and validation of numbers, identifications, sizes, and sex of turtles will be crucial. I conducted a mark-recapture survey of freshwater turtles in six eastern Piedmont ponds: three of which had been harvested and three of which had no record of harvest. I tested for differences in sex ratios, size and age distributions, and population densities between the harvested and unharvested populations of Yellow-bellied Sliders (Trachemys scripta). Although no significant differences were found between the two types of populations, the amount of variance in the results does not allow any clear conclusions to be drawn. Severe weather impacts on habitat may have influenced sampling results. More research is required to determine the true effects turtle harvesting has on populations, including extensive stage-based simulation modeling and determination of metapopulations.
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Bernacki, Lucas Edward. "The Molecular Evolution of Non-Coding DNA and Population Ecology of the Spiny Softshell Turtle (Apalone spinifera) in Lake Champlain." ScholarWorks @ UVM, 2015. http://scholarworks.uvm.edu/graddis/289.
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ABSTRACT
Spiny softshell turtles (Apalone spinifera) occur at the northwest limit of their range in Lake Champlain. This species, although widespread across North America, is listed as threatened in Vermont due to habitat destruction and disturbances of anthropogenic origin. The population of spiny softshell turtles in Lake Champlain is isolated from other North American populations and is considered as an independent management unit. Efforts to obtain information on the biology of spiny softshell turtles in Lake Champlain precede 1936 with conservation measures being initiated in 1987.
Methods of studying spiny softshell turtles in Lake Champlain have included direct observation, mark-recapture, nest beach monitoring, winter diving, and radio telemetry. Each of these approaches has provided some information to the sum of what is known about A. spinifera in Lake Champlain. For example major nesting beaches, hibernacula, and home range size have been determined. Currently spiny softshell turtles primarily inhabit two areas within Lake Champlain, Missisquoi Bay and the mouth of the Lamoille River. However, the population structure and gene flow between spiny softshell turtles inhabiting the Lamoille and Missisquoi regions remained unknown.
A GIS model was created and tested in order to identify additional nesting beaches used by spiny softshell turtles along the Vermont shores of Lake Champlain. Although some additional small potential nesting beaches were found, no additional major nesting sites were found. The GIS model identified the mouth of the Winooski River (the site of a historical population) as potentially suitable nesting habitat; however, no evidence of spiny softshell turtle nesting was found at this site.
A series of methods developed for collecting molecular and population genetic data about spiny softshell turtles in Lake Champlain are described, including techniques for DNA extraction of various tissue types and the design of new primers for PCR amplification and sequencing of the mitochondrial control region (mtD-loop). Techniques for circumventing problems associated with DNA sequence alignment in regions of a variable numbers of tandem repeats (VNTRs) and the presence of heteroplasmy within some individuals are also described. The mtD-loop was found to be a suitable marker to assess the genetic structure of the Lake Champlain population of spiny softshell turtles. No significant genetic sub-structuring was found (FST=0.082, p=0.223) and an indirect estimate of the migration rate between Lamoille and Missisquoi regions of Lake Champlain was high (Nm>5.576).
In addition to consideration of A. spinifera in Lake Champlain, the mtD-loop was modeled across 46 species in 14 families of extant turtles. The primary structure was obtained from DNA sequences accessed from GenBank and secondary structures of the mtD-loop were inferred, (from thermal stabilities) using the program Mfold, for each superfamiliy of turtles. Both primary and secondary structures were found to be highly variable across the order of turtles; however, the inclusion of an AT-rich fold (secondary structure) near the 3' terminus of the mtD-loop was common across all turtle families considered. The Cryptodira showed conservation in the primary structure at regular conserved sequence blocks (CSBs), but the Pluerodira displayed little conservation in the primary structure of the mtD-loop. Overall, greater conservation in secondary structure than primary structure was observed in turtle mtD-loop. The AT-rich secondary structural element near the 3' terminus of the mtD-loop may be conserved across turtles due to it serving a functional role during mtDNA transcription.
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Read, Tyffen Chloe. "Population Structure, Migration and Habitat Ecology of the Green Turtle (Chelonia mydas) in the Grand Lagon Sud of New Caledonia." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/367599.
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Conservation management of wildlife populations requires a comprehensive understanding of the population structure, movement and ecology of threatened and endangered species. The green turtle, Chelonia mydas, is a species found in both tropical and subtropical waters worldwide and since 1982 is listed as endangered on the IUCN red list of threatened species. While C. mydas is afforded protection in many areas of the Pacific it still faces significant threats, both anthropogenic (e.g. by-catch from commercial and recreational fishing, directly targeted as a food sources by in-digenous groups and boat strikes) and environmental (e.g. climate change, coastal pollution and habitat degradation). These threats are real for C. mydas in New Caledonia (NC), however strate-gies to mitigate the threats are lacking as vital information on the C. mydas population structure, movement patterns and habitat use in NC is scant. Proof of C. mydas migration within the South-west Pacific, including linkages with NC and other Pacific countries, has been shown however more comprehensive data is needed. Furthermore, preliminary data suggest the Grand Lagon Sud (GLS) in NC provides important foraging grounds for C. mydas. However, identifying the spatial extent and habitat value of these foraging grounds is a challenge due to the complexity of the C. mydas life cycle and the species tendency for large scale migrations.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
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Beshara, Andrea L. "Determining population boundaries and densities of red-eared slider turtles (Trachemys scripta) : an empirical field test /." Read thesis online, 2009. http://library.uco.edu/UCOthesis/BesharaAL2009.pdf.
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Colteaux, Benjamin C. "The Status of Snapping Turtles (Chelydra serpentina) in Virginia: Population Viability, Demography, Regulatory Analysis, and Conservation." VCU Scholars Compass, 2017. https://scholarscompass.vcu.edu/etd/5162.
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Snapping turtles (Chelydra serpentina) are being harvested in unprecedented numbers in the United States (US) to meet the needs of international markets. Over three million live snapping turtles from farm and wild caught stock were exported from the US to Asia in 2012-14 alone. In the Commonwealth of Virginia, records indicate that 29,860 snapping turtles were commercially harvested between 2000 and 2015. Size limits are often used to regulate harvest pressure in snapping turtles and other game species. I analyzed the historic harvest of eleven US states to test the efficacy of minimum-size limit regulations at reducing commercial harvest pressure. Further, I conducted a four-year mark-recapture study on three Virginia waterways that have each experienced a different level of historic commercial harvest. As part of the larger mark/recapture project, I conducted radio telemetry on 23 turtles to examine seasonal, body size, and sex-specific effects on home range size of snapping turtles in a lotic system. I incorporated survival and growth rates from this study, demographic rates from the literature, and state-collected harvest rates into a hybrid age/stage population matrix model to estimate the population growth rate at three harvest levels (0%, 21%, 58%) that were estimated based on annual commercial landing reports on file with the Virginia Department of Game and Inland Fisheries. I used the model to test population viability under multiple size limit regulations, and used sensitivity analyses to identify adult stages most critical to the overall population growth rate.
Based on model estimates, size-limits were effective at reducing harvest by 30-87% in years with high harvest pressure. However, most size limit regulations result in the removal of larger breeding adults, which has been shown to be detrimental to long term population viability. Based on radio-telemetry data, I found evidence that snapping turtles utilize lotic and lentic habitats differently, which can have implications for management of this iconic species. Matrix population modelling predicted that population densities at the moderate and high harvest site were reduced by 47% and 62%, respectively, when compared to the no harvest site. Model results indicate that, while an increase to the minimum-size limit in 2012 protected a larger portion of the population, that the commercial harvest of snapping turtles in the Commonwealth of Virginia is not sustainable under current state regulations. Our analysis suggests that minimum-size limits of 35.6 cm curved carapace length or greater will maintain viable populations by protecting a larger portion of reproducing snapping turtles within a population.