Rozprawy doktorskie na temat „Sentinels species”
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Sauser, Christophe. "Les oiseaux marins polaires, sentinelles de la glace de mer : Réponses démographiques et traits d’histoire de vie". Thesis, La Rochelle, 2020. http://www.theses.fr/2020LAROS027.
The impact of climate change on sea ice and polar ecosystems has been well recognized. However, these environments are generally difficult to study because of their extreme climate, isolation and the associated logistical difficulties. The lack of knowledge regarding the mechanisms linking the life history traits of polar organisms and sea ice variation limit our understanding of the consequences of climate change on long-lived species such as polar seabirds and sea ice ecosystems. Seabirds, generally located at the top of food webs, could however constitute sentinel species of ecosystems linked to sea ice. The objective of this thesis is to improve knowledge on the processes involved in the responses of polar marine predators to environmental variations, and mainly the mechanisms linked to sea ice. For this purpose we have based our analyses on the long-term monitoring of two polar seabirds, the snow petrel (Pagodroma nivea) and the Cape petrel (Daption capense). Both species breed in polar environments of the Southern Ocean. One is particularly dependent on sea ice for foraging (snow petrel) while the other prefers ice-free habitats (Cape petrel). During this PhD, we estimated the influence of extrinsic factors (top-down, bottom-up, local weather) and intrinsic factors (age, breeding experience, sex and colony) on the demographic responses of these two species using multi-states capture-recapture models. We also tested the influence of environmental factors on phenotypic traits (body condition and breeding phenology) of snow petrels. For the Cape petrel, we show a decrease in breeding success as well as an influence of several extrinsic parameters (sea surface temperature, predation, local weather) on this demographic parameter. We also show an increase in adult survival linked to variations of a large scale climate index, the southern annular mode. Modelling of the population dynamics using a matrix population model indicated a positive population growth rate and suggest that this species probably beneficiates from current climate changes. In snow petrels, we demonstrate the influence of sea ice and other extrinsic factors (predation, southern annular mode, local weather) as well as intrinsic factors (sex, colony, breeding experience) on multiple demographic traits (probabilities of survival, breeding, hatching, and fledging). We also show a shift (delay) in the breeding phenology of snow petrels in response to environmental changes (sea ice concentration, winds), and found that delayed reproduction negatively impacted the probability of fledging. Finally, we show that the sea ice concentration and the southern annular mode have a negative influence on the survival and body condition of juvenile snow petrels. This thesis provides new knowledge on the links between sea ice and the life history traits of two Antarctic polar seabirds characterized by specific dependence to sea ice. This knowledge helps to better understand the consequences of climate change on polar seabirds and polar ecosystems in general, and contributes to the understanding of population dynamics concerning intra-specific demographic variations at a fine spatial scale
Donnelly, Robert Kevin. "An investigation of genetic heterogeneity in a biological sentinel species (Lumbricus rubellus)". Thesis, University of South Wales, 2011. https://pure.southwales.ac.uk/en/studentthesis/an-investigation-of-genetic-heterogeneity-in-a-biological-sentinel-species-lumbricus-rubellus(ab114364-d43b-49c2-b309-6cecd95dcaf2).html.
Guillot, Héloïse. "L’herpetofaune, sentinelle de l’accumulation et des effets des contaminants environnementaux ?" Thesis, La Rochelle, 2017. http://www.theses.fr/2017LAROS024/document.
The development of industrial and agricultural activities over the last century has resulted in the release of chemicals into the environment, which contaminate ecosystems and can accumulate in plants, sediments and across food webs. As such, it is essential to conduct an assessment of the ecological risk associated with the presence of these compounds in natural environments. Achieving this can be aided through the study of sentinel species, which can be used to determine exposure rates of individuals and assess how these subsequently impact wildlife. Amphibians and reptiles display ecological and biological characteristics that may make them particularly attractive as sentinel species. The collection of studies presented in this thesis aims to determine the availability of contaminants in the environment and estimate the effects of this on individual traits of living organisms. Across several species of reptiles and amphibians we, (i) measured levels of pollutants accumulated in the tissues of several reptile species ; (ii) assessed how contaminated habitats impact the morphology of adult common toads (Bufo bufo) ; and (iii) experimentally measured the influence of a molecule frequently detected in the environment on common toad tadpoles’ growth. Results show that reptiles efficiently accumulate organic pollutants and metal trace elements in their tissues, and thereby allow efficient evaluation of the global contamination of an area, as well as the occurrence of localized pollution events. In addition, our work shows an influence of the agricultural habitat on the morphology of adult common toads, which is potentially a consequence of the presence of chemicals in these environments. Finally, we were able to demonstrate an effect of low concentrations of AMPA, the main metabolite of glyphosate, on the development of common toad tadpoles. Amphibians are therefore efficient organisms to study the impact of environmental contamination on individual characteristics. Our work shows the usefulness of certain species of reptiles and amphibians as sentinel species for the presence of contaminants in the environment, and their potential impact on organisms. Ecotoxicological studies on these organisms remain too scarce, and it is imperative to develop research in this field, to participate effectively in the assessment of environmental risk
Bissett, Wesley Thurlow Jr. "Ecosystem health at the Texas coastal bend: a spatial analysis of exposure and response". Texas A&M University, 2007. http://hdl.handle.net/1969.1/85889.
de-la-Ossa-Carretero, Jose Antonio. "Assessing sewage disposals in soft-bottom habitats". Doctoral thesis, Universidad de Alicante, 2011. http://hdl.handle.net/10045/24056.
Ciliberti, Alexandre. "Le Varan du Nil (Varanus niloticus), indicateur de la pollution des zones humides d’Afrique Sub-Saharienne". Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10241/document.
In Africa, metal and pesticide contamination of wetlands is supposed to continue on a permanent basis. However, the ecotoxicological status of these ecosystems remains poorly documented. The aim of the present work is to assess the value of the Nile monitor (Varanus niloticus) as a sentinel species for the environmental contamination of continental wetlands in sub-Saharan Africa. Lead and cadmium on the one hand, and organochlorine and organophosphate pesticides on the other, have been quantified in several tissues by atomic absorption spectrophotometry and gas chromatography, respectively. Samples come from 71 specimens originating from four sites considered unequally contaminated (in Mali and Niger). Although clear differences appear between sites, the environmental contamination turns out to be moderate at the four sites, and does not seem to represent a significant risk neither for the monitors themselves, nor for occasional human consumers. However, the interindividual variability is important. The organotropisms relative to the detected pollutants are consistent with those described in previous studies. Concerning the pesticides, no gender effect has been found, whereas females were more contaminated by metals. The relation between other factors (size, proportion of fat) and tissue concentrations has been considered too. Nile monitors can reveal subtle differences in local pollution and the spatial resolution of this tool seems to be very sharp. Its practical relevance is thus validated. Additionally, an experimental work has been carried out on captive monitors to go into the subject in greater depth
Spafford, Mark D. "Trout-perch Percopsis omiscomaycus (Walbaum) and lake chub Couesius plumbeus (Agassiz), as sentinel monitoring species in the Athabasca River, Alberta". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0017/MQ47100.pdf.
Wahls, James Charles Edgar. "Host-Parasitoid Interactions of Two Invasive Drosophilids in Virginia Fruit Crops". Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/77690.
Master of Science in Life Sciences
Olsen-Mikitowiez, Victoria Michaelina. "Prevalence of Dirofilaria Immitis, The Causitive Agent in Canine Heartworm Disease, in Arizona from 2008 to 2011 Using Feral Canines as a Sentinel Species". Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/144918.
Barhoumi, Badreddine. "Biosurveillance de la pollution de la lagune de Bizerte (Tunisie) par l’analyse comparée des niveaux de contamination et de l’écotoxicité des sédiments et du biote". Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0075/document.
The objective of this thesis was the diagnosis of the health status of the Bizerte lagoon using a multi-marker (chemical, biochemical and morphometric) and multi-compartment approach (sediment and biota). To achieve this objective, the selected biological models were the mussel Mytilus galloprovincialis and the goby fish Zosterisessor ophiocephalus. Both species are widespread in the Bizerte lagoon and the Mediterranean Sea. In a first part and in order to estimate the levels of contamination of the Bizerte lagoon, persistent organic pollutant (POPs), granulometric and mineralogical (TOC) analyses of surficial sediments were carried out. Afterwards, the potential toxicity of sediments was assessed by a battery of bioassays. In a the third part, bioavailability and ecotoxicological impact of POPs studied were assessed by bioaccumulation measurement in these two indicators species, and the study of biological responses associated through a battery of biomarkers such as catalase (CAT), thiobarbituric acid (TBARS); Ethoxyresorufin O-deethylase (EROD); glutathione-S-transferase (GST) and acetylcholinesterase (AChE). The main results of the chemical analyses show a general contamination of sediments and organisms studied by POPs. Contamination levels are dependent on the studied species and stations. Comparing our values with literature data, showed that the levels of contamination of the lagoon are similar or slightly lower than equivalent ecosystems in other parts of the world. Besides, the estimation of sediment toxicity, using sediment guideline values (ERL, ERM, TEL et PEL), as well as bioassays (Microtox®, SOS-Chromotest® and MELA test) showed that stations of canal of Bizerte S1 and S3 were associated with an increased hazard to aquatic organisms. Our results showed that biomarkers measured in both selected species are sensitive and inducible parameters, which allowed to characterize the health status of organisms and global quality of the studied environment. Biochemical but not morphometric markers allowed to discriminate the different studied sites according to chemical risk. Unlike fish, it has been demonstrated in mussels that abiotic factors influence the concentrations of POPs and biomarker responses.Obtained data suggest that integrative approach, combining chemical and ecotoxicological measurements, may represent a good way to asses the quality of the environment, particularly, in the context of biomonitoring programs
Patrick, Sean Mark. "Testicular apoptotic activity in two bio-sentinel fish species inhabiting an aquatic ecosystem in an area where continual DDT spraying occurs : utility of immunohistochemical assays". Diss., University of Pretoria, 2008. http://hdl.handle.net/2263/26120.
Dissertation (MSc)--University of Pretoria, 2008.
Physiology
unrestricted
Nugent, Graham. "The role of wild deer in the epidemiology and management of bovine tuberculosis in New Zealand". Phd thesis, Lincoln University. Bio-Protection and Ecology Division, 2005. http://theses.lincoln.ac.nz/public/adt-NZLIU20070212.130927/.
Michelot, Candice. "Le manchot Adélie, sentinelle de la glace de mer : étude du comportement de recherche alimentaire en réponse aux variations environnementales en période de reproduction". Thesis, La Rochelle, 2020. http://www.theses.fr/2020LAROS009.
A central question in ecology is the understanding of the environmental change effects on organisms and on the ecosystem functioning. The Arctic and Antarctic warm faster than any other region on Earth, which has consequences on the sea-ice state and by extent on polar species which depend on it for their breeding and feeding activities. The main objective of my PhD was to determine the behavioural responses of a bio-indicator species, the Adélie penguin, during its foraging activity facing variable sea-ice conditions, at different species levels : individual, population, inter-population. We use a foraging activity dataset (GPS data, diet) on Adélie penguins obtained collected each year since 2010 in Terre Adélie (East Antarctica), at each breeding season in several colonies. We highlight foraging behavioural variations in that species related to sea-ice conditions and dynamics, but similar responses between individuals and between colonies facing comparable environmental conditions. Our results highlight the importance of specific habitats and sea-ice conditions for an optimal foraging activity. We discuss about intrinsic and extrinsic factors at the origin of the observed variations, and of the implication of such variations on the reproductive behaviour of Adélie penguins. Those PhD results are replaced in a context of ecosystem conservation for the implementation of efficient protection measures based on the ecology of sentinel species
Gibbs, Samantha E. J. "Peridomestic avian species as amplifying hosts and sentinels of West Nile virus in Georgia". 2005. http://purl.galileo.usg.edu/uga%5Fetd/gibbs%5Fsamantha%5Fe%5F200508%5Fphd.
Directed by David Stallknecht. Includes articles published in Journal of wildlife diseases, and Clinical and diagnostic laboratory immunology, and articles submitted to Vector borne and zoonotic diseases. Includes bibliographical references.
Havelka, Ondřej. "Klasifikace druhové skladby lesa pomocí dat Sentinel-2 a Landsat". Master's thesis, 2018. http://www.nusl.cz/ntk/nusl-388320.
Ramos, Ana Sofia Soares. "Biomonitoring of Coastal Contamination Using a Biomarker Approach: The Use of Pollicipes Pollicipes as a Sentinel Species". Dissertação, 2014. https://repositorio-aberto.up.pt/handle/10216/78336.
Ramos, Ana Sofia Soares. "Biomonitoring of Coastal Contamination Using a Biomarker Approach: The Use of Pollicipes Pollicipes as a Sentinel Species". Master's thesis, 2014. https://repositorio-aberto.up.pt/handle/10216/78336.
Lefebvre, Isabelle. "Impact des polluants agricoles sur la génétique des populations d’une espèce sentinelle : le ouaouaron (Rana catesbeiana)". Thèse, 2010. http://hdl.handle.net/1866/3862.
Agricultural expansion continues to act on the loss of critical habitats for the development of species and affects the integrity of remaining habitats. Although several species manage to survive in such inadequate ecosystems, persistence and health of many populations seem compromised by the intensive use of pesticides and fertilizers. This study aims at determining the impact of pollutants and landscape ecology on the genetic diversity of bullfrog populations inhabiting an agricultural area. Our hypothesis states that chronic exposure to agricultural pollutants induces genetic differences in exposed populations. The watershed of the Yamaska River was designated as the study site because it is part of the largest agricultural region in Quebec and because the sampling sites represent a gradient of land use for agriculture (low, moderate, high). The bullfrog was chosen as the biological model, since its physiological and ecological characteristics make it a sentinel species, which can reflect the overall health of an ecosystem. Population genetic characterization has been conducted from AFLP (Amplified Fragment Length Polymorphism) markers. The results show that genetic diversity is correlated to colonization from the mouth of the Yamaska River and that some populations are genetically differentiated. Furthermore, we demonstrated a positive relationship between the number of polymorphic loci and the atrazine, the contamination index and the nitrogen concentration as well as between expected heterozygosity and phosphate concentration.
Mashala, Makgabo Johanna. "Assessment and mapping of wetland vegetation as an indicator of ecological productivity in Maungani Wetland in Limpopo, South Africa". Thesis, 2020. http://hdl.handle.net/10386/3478.
Wetland vegetation provides a variety of goods and services such as carbon sequestration, flood control, climate regulation, filtering contamination, improve and maintain water quality, ecological functioning. However, changes in land cover and uses, overgrazing and environmental changes have resulted in the transformation of the wetland ecosystem. So far, a lot of focus has been biased towards large wetlands neglecting wetlands at a local scale. Smaller wetlands continue to receive massive degradation by the surrounding communities.Therefore, this study seeks to assess and map wetland vegetation as an indicator of ecological productivity on a small scale. The Sentinel-2 MSI image was used to map wetland plant species diversity and above-ground biomass (AGB). Four key diversity indices; the Shannon Wiener (H), Simpson (D), Pielou (J), and Species richness (S) were used to measure species diversity. A multilinear regression technique was applied to establish the relationship between remotely sensed data and diversity indices and AGB. The results indicated that Simpson (D) has a high relationship with combined vegetation indices and spectral band, yielding the highest accuracy when compared to other diversity indices. For example, an R² of 0.75, and the RMSE of 0.08 and AIC of -191.6 were observed. Further, vegetation AGB was estimated with high accuracy of an R² of 0.65, the RMSE 29.02, and AIC of 280.21. These results indicate that Maungani wetland has high species abundance largely dominated by one species (Cyperus latifidius) and highly productive. The findings of this work underscore the relevance of remotely sensed to estimate and monitor wetland plant species diversity with high accuracy.
Patrick, Sean Mark. "Testicular apoptotic activity in two bio-sentinel fish species inhabiting an aquatic ecosystem in an area where continual DDT spraying occurs utility of immunohistochemical assays /". 2009. http://upetd.up.ac.za/thesis/available/etd-07082009-171902/.