A considerable part of the global pool of terrestrial carbon is stored in high latitude soils. In these soils, repeated cycles of freezing and thawing creates soil motion (cryoturbation) that in combination with other cryogenic disturbance processes may play a profound role in controlling the carbon balance of the arctic soil. Conditions for cryogenic soil processes are predicted to dramatically change in response to the ongoing climate warming, but little is known how these changes may affect the ability of arctic soils to accumulate carbon. In this thesis, I utilize a patterned ground system, referred to as non-sorted circles, as experimental units and quantify how cryogenic soil processes affect plant communities and carbon fluxes in arctic soils. I show that the cryoturbation has been an important mechanism for transporting carbon downwards in the studied soil over the last millennia. Interestingly, burial of organic material by cryoturbation appears to have mainly occurred during bioclimatic events occurring around A.D. 900-1250 and A.D. 1650-1950 as indicated by inferred 14C ages. Using a novel photogrammetric approach, I estimate that about 0.2-0.8 % of the carbon pool is annually subjected to a net downward transport induced by the physical motion of soil. Even though this flux seems small, it suggests that cryoturbation is an important transporter of carbon over centennial and millennial timescales and contributes to translocate organic matter to deeper soil layers where respiration proceeds at slow rates. Cryogenic processes not only affect the trajectories of the soil carbon, but also generate plant community changes in both species composition and abundance, as indicated by a conducted plant survey on non-sorted circles subjected to variable differential frost heave during the winter. Here, disturbance-tolerant plant species, such as Carex capillaris and Tofieldia pusilla, seem to be favoured by disturbance generated by the differential heave. Comparison with findings from a previous plant survey on the site conducted in the 1980s suggest that the warmer temperatures during the last decades have resulted in decreased differential heave in the studied non-sorted circles. I argue that this change in cryogenic activity has increased abundance of plants present in the 1980s. The fact that the activity and function of the non-sorted circles in Abisko are undergoing changes is further supported by their contemporary carbon dioxide (CO2) fluxes. Here, my measurements of CO2 fluxes suggest that all studied non-sorted circles act as net CO2 sources and thus that the carbon balance of the soils are in a transition state. My results highlight the complex but important relationship between cryogenic soil processes and the carbon balance of arctic soils.

Algal blooms are directly related to human-caused nutrient enrichment of water bodies. The cyanobacteria Microcystis aeruginosa produces microcystin (MC), a toxin that has been linked with mortalities and illness of many organisms. We show that MC is not constrained by the aquatic-terrestrial ecotone. MC was detected in a primary consumer and emerging aquatic invertebrate (Hexagenia Mayfly), a terrestrial insect and predator of emerging aquatic invertebrates (Tetragnathidae Spider), and a vertebrate consumer (Prothonotary Warbler). Mayfly and spider MC levels varied across the blooming period. MC levels in prothonotary warbler livers varied by age class; nestlings having the highest levels. MC levels decreased in fledglings over time. A more aquatic diet was related to higher MC levels in nestlings at one site and nestling fecal-sacs varied spatially, also indicating that aquatic diet is related to MC consumption. Warbler body condition and growth rate was not related to liver microcystin levels.

Phylogeography aims to understand the processes that underlie the distribution of genetic variation within and among closely related species. Although the means by which this goal might be achieved differ considerably from those that spawned the field some thirty years ago, the foundation and conceptual breakthroughs made by Avise are nonetheless the same and are as relevant today as they were two decades ago. Namely, patterns of neutral genetic variation among individuals carry the signature of a species’ demographic past, and the spatial and temporal environmental heterogeneity across a species’ geographic range can influence patterns of evolutionary change. Aquatic systems throughout Mexico provide unique opportunities to study phenotypic plasticity and evolution in relation to climatic and environmental selective forces. There are several unique, often isolated aquatic environments throughout Mexico that have a history of geographic isolation and reconnection. The first study presented herein shows significant mitochondrial sequence divergence was also discovered between L. megalotis populations on either side of the Sierra de San Marcos that bisects the valley of Cuatro Ciénegas and that the populations in the valley are genetically distinct from those found outside of the valley. The second study recovered signals of two divergence events in Cuatro Ciénegas for six codistributed taxa, and reveals that both events occured in the Pleistocene during periods of increased aridity suggesting that climatic effects might have played a role in these species’ divergence. The final study presents an Illumina-based high-resolution species phylogeny for Astyanax mexicanus providing added support that there are multiple origins to cave populations and further clarifying the uniqueness of the Sabinos and Rio Subterráneo caves.

This study quantifies the changes in vegetation composition and structure of a fire-excluded Pinus palustris (longleaf pine) wetland savanna restoration site in southeastern in comparison to a proximate contemporary reference site. The restoration site was invaded by hardwood species and off-site pines, and never underwent extensive soil disturbance. The restoration treatments involved logging across portions of the site and the reintroduction of fire across the entire site. All species present in 10m2 quadrats were recorded prior to treatment and throughout the 17 year study at reference and treatment sites. The community composition of both logged and unlogged sites converged over time, and became more similar to the reference site. We conclude that logging of off-site pine coupled with the reintroduction of frequent fires can be effective in restoring ground cover in remnant longleaf pine savannas withdisturbance.

In Lake Pontchartrain Basin, commercial fishing in estuarine habitats impacts many non-target species collected as bycatch. I investigated the bycatch assemblages collected by commercial vessels and compared these to assemblages collected by typical fishery-independent methods. I compared assemblages using analysis of similarity (ANOSIM) and determined important species by weight and abundance using similarity percentages analyses (SIMPER). I also examined differences in size-class distributions by gear type using density kernel plots and Mann-Whitney U tests. The two gear types collected significantly different assemblages (ANOSIM R = 0.522, p = 0.001) and gear type explained more composition differences than other factors such as month, daytime, or location. Fishery-independent gear underestimated the importance of many species. Although fishery-independent data are invaluable for monitoring assemblage dynamics, fishery-independent gear collects different assemblages than commercial gear. Larger fishes of important species were caught less often in bycatch, but completely absent from fishery-independent gear.

Quantifying the impacts of restoration on coastal waterways is crucial to understanding their effectiveness. Here, I look at the impacts of multiple restoration projects on urban waterways within the city limits of New Orleans, LA, with an emphasis on the response of fishes. First I report the effects of two projects designed to improve exchange down estuary on the hydrologic characteristics of Bayou St. John (BSJ). Within BSJ, flow is dominated by subtidal wind driven processes. Removal of an outdated flood control structure did not appear to alter exchange in BSJ, but removal combined with sector gate openings did. I also refined a three dimensional hydrodynamic model of this system to have accurate predictions of velocity and elevation. Temperature and salinity were difficult to constrain with this model. Solutions of this model were used to compare flow metrics, along with linearly interpolated temperature, and other variables to Red Drum (Sciaenops ocellatus) activity and movement patterns. Relationships between Red Drum activity and velocity suggested a response to subtidal, wind driven flow. Overall, high Sedentariness, a measure of inactivity, was found suggesting high levels of site fidelity. Higher mean Sedentariness during the night was also found. I also used a pseudo-BACI design to analyze the fish assemblage response to removal of an outdated flood control structure and the impacts of sector gate openings on fish guild species richness in BSJ. Limited differences were found when comparing fish assemblages before and after removal, but these differences were likely due to a decrease in salinity not restoration efforts. No significant differences in Freshwater or Estuarine fish guild species richness was observed for any of the control or impact sites. Marine fish species richness was found to be higher immediately following sector gate openings at the site closest to the structure, suggesting an initial pulse of young marine organisms is provided via these events. The findings here can be used to optimize management of exchange flow in coastal impounded waterways.

L'imagerie terrestre urbaine se développe grâce à la diffusion grand public de visualisateurs immersifs au niveau de la rue. L'objectif de cette thèse est de proposer une méthode physique d'estimation de la réflectance des matériaux d'une scène urbaine à partir des images d'un système mobile d'acquisition, comme par exemple le véhicule d'acquisition Stereopolis, développé au laboratoire MATIS de l'Institut National de l'Information Géographique et Forestière (IGN).Pour cela, on considère que l'on dispose d'un modèle 3D de la scène, segmenté en zones de réflectance homogène (décrite par un modèle paramétrique), d'un jeu d'images géoréférencées corrigées radiométriquement. On propose une méthode d'estimation des réflectances par minimisation de l'écart entre les images réelles acquises par le capteur et des images simulées depuis le même point de vue. Après une modélisation phénoménologique des différentes composantes de la luminance arrivant au niveau d'un capteur imageur dans le domaine visible, une méthode utilisant le lancer de rayons sert à simuler cette luminance. Cela constitue ici le problème direct. Cet outil de simulation nécessite la connaissance de l'illumination de la scène, i.e. la répartition et la puissance des sources de lumière. Pour une acquisition avec Stereopolis, on ne réalise généralement pas de mesures atmosphériques et/ou radiométriques permettant de déterminer l'illumination avec des codes de transfert radiatif ; c'est pourquoi on propose une méthode d'estimation de la luminance du ciel à partir des images, en utilisant les pixels qui voient le ciel. L'éclairement solaire direct, non accessible directement dans les images, est estimé par une méthode ombre-soleil grâce à une plaque de référence placée sur le toit du véhicule. L'algorithme d'inversion du système se fait par minimisation d'une fonction coût constituée par la différence pixel à pixel entre les images simulées avec certains paramètres de réflectance et les images réelles. Cela nécessite de nombreuses simulations par lancer de rayons, car l'algorithme est itératif en raison des réflexions multiples entre les objets qui doivent être calculées avec des paramètres de réflectances initiaux. Afin d'éviter ces très coûteux lancers de rayons, on propose un algorithme de lancer de rayons formel qui stocke la luminance simulée comme des fonctions des paramètres de réflectances au lieu d'une valeur numérique. Cela permet de mettre à jour les images de luminance simulées par simple évaluation de ces fonctions avec le jeu de paramètres courant. La minimisation elle-même est effectuée par la méthode du gradient conjugué. Des résultats sur des scènes synthétiques permettent de faire une première validation de la méthode. Cependant, l'application sur un jeu d'images issues de Stereopolis pose plusieurs difficultés, notamment liées l'étalonnage radiométrique et à la segmentation du modèle 3D utilisé en entrée / Urban terrestrial imagery is widely used through online viewers of street-level images. The MATIS of the French National Geographical and Forester Data Institute (IGN) has developed its own mobile-mapping vehicle, Stereopolis, dedicated to research purposes. In this thesis, we develop a physically-based method to retrieve the reflectance of urban materials from a set of images shot by a mobile-mapping vehicle. This method uses a 3D model of the scene (segmented in areas of homogeneous reflectance, modeled by a parametric formula) and a set of georeferenced and radiometrically corrected images. We present a method for the estimation of the reflectances of the materials by minimizing the difference between real acquired images and simulated images from the same point of view. A modelisation of the physical phenomena leading to the formation of optical images is presented. A code using ray-tracing algortihm is used to compute the radiance at the sensor level. This is the direct problem for our estimation of reflectances. The illumination of the scene must be an input of this simulation tool; now, in a typical urban mobile-mapping acquisition neither atmospheric nor radiometric measurements are performed, that could be used to determine the illumination with a radiative transfer code. We propose an estimation of the illumination using directly the sky pixels in the acquired images. The direct solar irradiance cannot be estimated from the images because of overexposure, but we can use a shadows casted on a dedicated reference plate placed on top of the vehicle. The reflectances estimation is performed by minimizing a cost function; this cost function is the pixel-wise difference between simulated images (with current reflectances parameters) and acquired images. This leads to numerous ray-tracing simulations as the algorithm is iterative due to interreflections between the objects of the scene, that are computed using initial parameters. In order to prevent these costly ray-tracing simulations, we propose a symbolic ray-tracing algorithm that computes the radiance as a symbolic function of the reflectances parameters instead of a numerical value. Then, each iteration of the minimization algorithm is only an evaluation of a symbolic function. Results are shown on synthetic scenes to perform a first validation the estimation method. Using this method on real Stereopolis images remains difficult, mainly due to the radiometric calibration of cameras and the segmentation on the 3D model

O presente estudo teve como objetivo avaliar o custo energético e alguns aspectos da biomecânica associados à locomoção em Cebus apella (macaco-prego). Para tanto, medidas de taxa metabólica (consumo de oxigênio) e de parâmetros cinemáticos (freqüência de passos, tempo de contato das patas com o plano de apoio, comprimento dos passos e amplitudes de flexão e extensão de juntas e segmentos corpóreos) foram obtidas com os sujeitos experimentais se locomovendo sobre esteira rolante. Nossos resultados mostram que apesar da espécie estudada exibir freqüência de passos inferior ao esperado para mamíferos quadrúpedes de massa corpórea similar, esse parâmetro cinemático é o elemento preferencial do padrão de locomoção que é ajustado para que o animal possa suportar as novas condições do meio (alteração de velocidade). Em adição, os dados de consumo de oxigênio obtidos neste estudo indicam que diferenças significativas não devem ser esperadas entre o custo energético da locomoção de quadrúpedes primatas e não primatas. Sendo assim, foi possível inferir que um outro elemento, além da taxa de geração de força (inferida a partir da freqüência de passos), pode responder pela magnitude do custo energético da locomoção em primatas. Nossas inferências sugerem que características anatômicas de primatas (maior volume muscular associado aos membros posteriores) podem constituir-se no elemento central para o entendimento do custo metabólico exibido pela espécie estudada (similar a quadrúpedes não primatas). Por fim, deve ser salientado que nossos dados indicam que a flexão da coluna pode ser um importante mecanismo para armazenamento de energia (energia elástica) durante a locomoção em Cebus apella, sobretudo em velocidades mais altas. / This study aimed to evaluate the energy expenditure and biomechanical aspects associated to the locomotion of Cebus apella (capuchin monkey). Measurements of metabolic rate (oxygen consumption) and kinematic parameters (stride frequency, foot contact time, step length and degree of flexion-extension of the joints and body segments) were obtained with the experimental subjects moving on a motorized treadmill. Our results show that although the species studied displays a lower stride frequency than quadruped mammals with similar body masses, this is the kinematic parameter that is preferentially adjusted by the animal to cope with faster velocities. In addition, oxygen consumption data obtained in this study indicate that significant differences between the energy cost of locomotion of primates and nonprimates quadrupeds should not be expected. Based on this result, we suggest that another element besides the rate of generating force (inferred from the stride frequency) could explain the energy cost of locomotion in primates. We suggest that anatomic characteristics of primates (larger muscular volume associated with the hind limbs) might be a key element to understand the cost of locomotion showed by capuchin monkeys (similar to non-primate quadrupeds). Our results also indicate that flexion of the column can be an important mechanism for elastic energy storage during locomotion in Cebus apella particularly at higher velocities.

As mudanças climáticas influenciarão as médias de temperaturas ambientais e a frequência de eventos extremos com consequências ainda desconhecidas para a fauna. Conhecer os limites fisiológicos dos organismos ao aumento de temperatura pode ajudar a ampliar os marcos conceituais dos impactos regionais das mudanças climáticas sobre a fauna. Este trabalho abordou como a diversidade fisiológica representada pela tolerância termal da fauna de artrópodes terrestres estava relacionada entre os biomas do Brasil, em uma perspectiva macrofisiológica (ampla escala espacial). Especificamente, coletou-se a temperatura crítica máxima (TCMax) de espécimens de artrópodes das Classes Arachnida, Chilopoda, Dipoploda, Entognatha (Collembola), Insecta e Malacostraca (Oniscidea) nos biomas de Mata Atlântica (strictu sensu), Mata Atlântica de Altitude, Cerrado, Amazônia e Caatinga. Os artrópodes foram utilizados como modelo de estudo por permitirem uma associação mais clara com a teoria disponível sobre limites fisiológicos e o ambiente físico. Assim, foram investigados padrões de variação da TCMax entre e dentro dos biomas, considerando ou não a categoria sistemática. Igualmente, foi avaliada a relação da TCMax da fauna de artrópodes com variáveis bioclimáticas representantes do ambiente termal nos biomas. No aspecto de margem de segurança termal, avaliou-se a potencial tolerância ao aquecimento da fauna de artrópodes nos biomas. Os resultados mostraram que existe ampla diversidade fisiológica da fauna de artrópodes, com padrões atrelados aos biomas do Brasil. A relação do padrão de tolerância termal dos espécimens de artrópodes com o bioma é complexa, havendo nuances de variação dentro e entre os biomas. Houve grande proporção de fauna termotolerante no bioma da Caatinga e menor proporção de fauna termotolerante na Mata Atlântica. Quanto às margens de segurança termal, os dados de tolerância ao aquecimento sugerem que não há grande susceptibilidade ao aquecimento da fauna de artrópodes nos biomas do Brasil. Este trabalho contribui para ampliar a discussão dos possíveis impactos das mudanças climáticas em seus aspectos regionais, tendo em vista a diversidade fisiológica da fauna de artrópodes terrestres nos biomas brasileiros. Igualmente, os dados podem servir como uma importante base para a incorporação em avaliações globais da vulnerabilidade dos ectotérmicos frente às mudanças do clima / Climate change will affect the average environmental temperatures and the frequency of extreme events with still unknown consequences for wildlife. To understand the physiological limits of organisms in relation to the increase in environmental temperature can help extend the conceptual frameworks of climate change regional impacts on wildlife. This work discussed how the physiological diversity represented by the thermal tolerance of terrestrial arthropod fauna was related among biomes of Brazil in a macrophysiological perspective (large spatial scale). It was collected critical thermal maximum (CTMax) of specimens of the class Arachnida, Chilopoda, Dipoploda, Entognatha (Collembola), Insecta and Malacostraca (Oniscidea) in the biomes of the Atlantic Forest (strictu sensu), Atlantic Forest Highland, Cerrado (Brazilian Savanna), Amazonia and Caatinga. The arthropods were used as model to allow a better association with the available theory of physiological limits and the physical environment. Thus, it was investigated variation in patterns of CTMax between and within biomes considering or not the systematic category. It was also evaluated the relationship of CTMax of the arthropod fauna with bioclimatic variables as representative of the thermal environment in the biomes. In terms of thermal safety margin, it was evaluated potential warming tolerance of the arthropod fauna in the biomes. The results showed that there is a broad physiological diversity of arthropod fauna with patterns linked to brazilian biomes. The ratio between thermal tolerance patterns of arthropod specimens and the biome is complex, there were varying nuances within and between biomes. There is a large proportion of thermotolerant fauna in the Caatinga biome and a lesser proportion of thermotolerant fauna in the Atlantic Forest. The warming tolerance data suggest that the susceptibility to heat of the arthropod fauna in brazilian biomes is small. This work will help to expand discussions of potential impacts of climate change regional aspects considering the view of the physiological diversity of terrestrial arthropod fauna in the brazilian biomes. In addition, the data can be as an important basis for incorporation into global vulnerability assessments on terrestrial ectotherms in view of climate change

Made available in DSpace on 2016-08-10T10:55:37Z (GMT). No. of bitstreams: 1 Fabio Henrique Ribeiro.pdf: 1472181 bytes, checksum: 70e834664a56ef82dbf61398ecb51b4b (MD5) Previous issue date: 2008-09-24 / This work analyses the perception of the professional driver about his work conditions, environment and health. The objective was to identify the difficulties met by the professional driver in the exercise of the profession, to verify his labor and health conditions, his perception of environmental changes and the kind of support received on the highways of the state of Goiás. It is a descriptive and exploratory study that uses a questionnaire (N=83) with questions about sociodemographic and anthropometrics characteristics; labor performance; self health evaluation; work related environment; general well-being using a scale developed by Fazio (1971) and used by Lima Paula e Torres (2001). The data on the accidents occurred between 2006 and 2007 in Goiás federal highways was obtained from the PRF-GO database. Within that period, 872 motorway accidents were registered, most involving males. In a total of 456 deaths, 256 were the drivers. The majority of accidents involved small vehicles, followed by tractor trucks and trucks. The average age of the participants was 42,8 years old, all male. The anthropometrics profile provided by corporal mass index (CMI) was 26,19 kg/m² of which 51,6% was overweight and 12% obese. On the level of school education, the predominance was incomplete elementary education with 39,8%. Most participants were married, with an average family income between R$1,501.00 and R$2.000,00, and 72% of the families depended solely on the participants income. Out of 83 interviews, 75,9% had a type E professional driver s license, and 26,5% owned the vehicle. The average professional time was 13,8 years. The well-being scale presented an average of 3,2 (DP=0,8), which indicates physical and psychological well-being bellow of medium point of the scale (4). Approximately 63% do not take regular medical examination. On average, 43,4% had medical exams over 2 years ago, 19% said that they suffer from some illness. On the perception of the environment, 71% have noticed environmental degradation. The results of research allows to conclude that the job of truck driver demands great ability of the worker, but the conditions where it is performed imposes physical and psychological demands that interfere with professional performance and road safety. / O presente trabalho trata da análise da percepção do motorista profissional sobre suas condições de trabalho, ambiente e saúde. O objetivo do trabalho foi conhecer as dificuldades encontradas pelo motorista de trânsito rodoviário no exercício de sua profissão, verificar suas condições de trabalho e saúde, sua percepção em relação às mudanças ambientais, bem como o tipo de apoio que recebe nas rodovias de Goiás. Trata-se de um estudo descritivo e exploratório que utilizou como instrumento um questionário (N=83) contendo perguntas sobre características sócio-demográficas e antropométricas, desempenho laboral; autoavaliação sobre a saúde; meio ambiente relacionado ao trabalho; escala do bemestar geral, desenvolvida por Fazio (1971) e utilizada por Lima Paula e Torres (2001). O levantamento de acidentes ocorridos entre os anos de 2006 e 2007 em rodovias federais de Goiás, foi obtido do banco de dados informatizado da PRFGO. Neste período, ocorreram 872 acidentes terrestres, com maioria de envolvidos sendo do sexo masculino. Em um total de 456 óbitos, 256 foram condutores dos veículos. O maior índice de acidentes ocorreu com automóveis, seguido de caminhão trator e caminhão. A média da idade dos participantes da pesquisa foi de 42,8 anos, todos do sexo masculino. O perfil antropométrico dado pelo índice de massa corpórea (IMC) foi de 26,19kg/m² onde 51,6% estavam acima do peso e 12% obesos. Quanto ao grau de escolaridade, a predominância foi o ensino fundamental incompleto, com 39,8%. Em relação ao estado civil, há predominância de casados. A renda familiar está entre R$1.501,00 e R$2.000,00 e 72% das famílias dos participantes depende exclusivamente de seu trabalho. Dos 83 entrevistados, 75,9% possuíam a CNH categoria profissional E e 26,5% eram donos do veículo. Quanto ao tempo de trabalho, a média apurada foi de 13,8 anos. A escala de bem-estar apresentou média de 3,2 (DP= 0,8), indicando o bem-estar físico e psicológico, abaixo do ponto médio da escala (4). Aproximadamente 63% responderam que não fazem regularmente exames de saúde, e em média, 43,4% realizaram há mais de dois anos o último exame de saúde, 19% alegaram ter alguma doença. Sobre a percepção do meio ambiente, 71% dos profissionais notaram a degradação ambiental. Os resultados da pesquisa permitem concluir que a profissão motorista de caminhão exige grande competência do trabalhador, e as condições em que ela é exercida provocam desgaste físico e psicológico que interferem na atuação do profissional e na segurança nas estradas.