Notre thème de recherche est parti du constat que les entreprises individuelles de moins de cinq salariés constituent la quasi-totalité des créations d'entreprises à Madagascar et qu’elles sont instables et éphémères. Nous les avons baptisées « petites entreprises de proximité » ou PEP, et appelé « imperfections » leur instabilité dans la durée, du point de vue de leurs activités, de leur statut institutionnel et en termes de croissance. Nous avons observé que leur multiplication traduisait l’engouement des entrepreneurs à leur endroit lequel traduisait leur adaptation à l’environnement. Dans un pays où les ménages étaient confrontés de manière endémique au problème d’emplois et de revenus, le phénomène de la PEP à travers la problématique suivante représente un sujet d’actualité et un enjeu majeur : - Si nous présumons que les "petites entreprises de proximité" sont adaptées à leur environnement, pourquoi sont-elles inaptes à durer, à grandir et à perdurer dans leur statut et dans leurs activités? - Et pourquoi les entrepreneurs continuent-ils d’en créer en dépit de « leurs imperfections » ainsi décrites ? Pour y répondre, nous avons avancé la proposition d’explication suivante sur les imperfections de la PEP : 1) Elles traduisent que la proximité instable, variable et complexe est à la fois un raccourci et un contre-exemple d’environnement ; 2) Elles sont nées des fonctionnalités structurelles et des mécanismes organisationnels mis en œuvre pour équilibrer l’adaptation tronquée de la PEP à l’environnement ; 3) Elles sont les facteurs de la dynamique d'intégration transformant des proximités agies en foyers de survie collective. Nous avons retenu deux postulats théoriques dans notre travail : l’existence d’écosystèmes pour la survie de la PEP, et un référent théorique fait d’écrits scientifiques et de connaissances renvoyant à la construction logique de son processus de survie. Nous avons mené le travail en trois étapes: _ Dans un premier temps, l‘étude des écarts entre la construction sociale de la réalité de la PEP et le référent théorique de son processus de survie a permis en partie de comprendre le phénomène de son adaptation et d’expliquer ses imperfections (Partie 1: Le positionnement théorique de notre proposition). _ Ensuite nous avons observé lesdits écarts mis à l’œuvre dans des processus empiriques de PEP en action, pour conclure qu’ils constituaient à la fois des symptômes de singularité d’organisations et des signaux de phénomènes traduisant de nouvelle manière de survivre (Partie 2 : La corroboration empirique de notre proposition). Nous avons ainsi avancé l’hypothèse théorique sur le maintien individuel de la PEP par sa survie collective avec ses parties prenantes en ces termes : Les PEP se forment grâce à des opportunités nées des imperfections des environnements qu'elles exploitent sous la forme de sous marchés résiduels. Elles se maintiennent en intégrant des proximités agies qu'elles transforment en niches dans une perspective de survie collective avec leurs parties prenantes. Leur mode d'adaptation les oblige à rester petites, éphémères et variables dans leurs activités. _ Enfin nous avons étudié les leçons d’expériences tirées de nos travaux et les pistes de réflexions qu’elles nous ouvraient. (Partie 3 : Les apports théoriques de notre étude sur la PEP). Nous nous sommes concentré sur les nouvelles tendances dans les formes organisationnelles adaptées à un environnement perçu à travers sa transformation, et sur celles d’un entrepreneuriat surfant sur le relationnel, la marginalité et la rareté des ressources. Nous avons conclu notre travail sur la PEP sur l’intérêt d’appréhender l’aptitude à la survie en termes d’écosystèmes. / Our research theme is based on the observation that individual companies with fewer than fiveemployees constitute almost all the enterprises created in Madagascar and that they are unstable and ephemeral. We called them "small proximity businesses" or PEP in french, and called "imperfections" their instability over time, from the point of view of their activities, their institutional status and in terms of growth.We observed that their multiplication reflected an entrepreneur's enthusiasm for creating them, which reflected their skill in adapting to their environment.In a country where households were confronted to an endemic problem of joblessness and lack ofincomes, the phenomenon of PEP through the following issue is a topical and a major concern:- If we assume that "small proximity businesses" are adapted to their environment, why are they unfit to last, grow and prosper in their status and activities?- And why do entrepreneurs continue to create them in spite of "their imperfections" thus described? To answer this question, we have proposed the following explanation on the imperfections of PEP:1) They show that the unstable, variable and complex proximity is both a shortcut and acounterexample of environment 2) They stem from structural functionalities and organizational mechanisms implemented to balancethe truncated adaptation of PEP to the environment; 3) They are the factors of the dynamics of integration transforming the agitated proximities into foci of collective survival.We retained two theoretical postulates for our research: the existence of ecosystems for the survival of PEP, and a theoretical referent made of scientific writings and knowledge referring to the logicalconstruction of its survival process. We conducted the work in three stages:_In a first step, the study of the differences between the social construction of the reality of the PEP and the theoretical referent of its survival process allowed but partly to understand the phenomenon of its adaptation and to explain its imperfections (Part 1: The theoretical positioning of our proposal)._Then we observed the called deviations through the empirical processes of PEPs in action, and concluded that they constituted as well symptoms of singularity of organizations and phenomena in a new way of surviving (Part 2: Empirical corroboration of our proposal)We have thus advanced the theoretical hypothesis on the individual maintenance of PEP by itscollective survival with its stakeholders: PEPs are formed through opportunities arising from the imperfections of the environments they exploit in the form of residual sub-markets. They are maintained by integrating agitated proximities that they transform into niches in a perspective of collective survival with their stakeholders. Their mode of adaptation forces them to remain small, ephemeral and variable in their activities._ Finally, we studied the lessons of experiences drawn from our work and the avenues of reflectionthey opened up to us. (Part 3: The theoretical contributions of our study on PEP) We focused on new trends in organizational forms adapted to an environment perceived through itstransformation, and on those of an entrepreneurship running through networks of contacts, marginality and scarcity of resourcesWe concluded our work on PEP on the importance of understanding survivability in terms of ecosystems

Les aquifères de socle fracturés très répandus en Bretagne, constituent des formations géologiques hétérogènes renfermant des ressources en eau. Ces structures sont souvent constituées d'une zone altérée et d'une zone fracturée. La zone altérée est peu épaisse et proche de la surface, elle est constituée de roches altérées envahies par l'eau souterraine qui y circule rapidement des hauts topographiques du bassin versant vers l'exutoire. L'eau y présente des temps de résidence courts (<20 ans) et est souvent polluée par les nitrates. La zone altérée située plus en profondeur et plus épaisse est constituée de roches dures traversées par des fractures. L'eau circule exclusivement au travers de fractures et lentement, le temps de résidence de l'eau y est donc long (>40 ans). Dans cette zone, l'eau est plus minéralisée et souvent riche en fer en Bretagne. Ces différentes circulations d'eau, induisent des conditions chimiques contrastées dans les zones altérée et fracturée, mais leur effet sur l'écosystème microbien des eaux souterraines n'a jamais été exploré. Cette étude montre que les circulations hydrologiques influencent à l'échelle régionale et locale la structuration des communautés microbiennes au sein des eaux souterraines d'aquifères de socle. La position d'une eau souterraine le long des voies de circulations des eaux souterraines dites « boucles hydrologiques » contrôle directement la structure des communautés microbiennes via le contrôle de la succession des donneurs et accepteurs d'électrons disponibles. Les communautés microbiennes analysées montrent une prédominance de Nitrobacter. Dans l'eau souterraine récente (<20 ans) donc principalement dans la zone altérée, les Nitrobacter. sont surtout des Comamonadaceae et Oxalobacteraceae, microorganismes versatiles et capables de dénitrifier. Dans l'eau souterraine ancienne (>40 ans) et isolée donc dans la zone fracturée, ce sont en grande majorité des Gallionellaceae, microorganismes microaérophiles spécialisés dans l'oxydation du fer(II). La prédominance des Gallionellaceae dans la zone fracturée suggère un écosystème profond basé sur l'oxydation du fer(II). Cependant, ce processus suppose une arrivée minimale d'oxygène dans la partie profonde, via par exemple un mélange avec une masse d'eau récente oxygénée. La proportion de Gallionellaceae dans les différentes eaux analysées montre une corrélation positive avec le degré de mélange des eaux anciennes avec des eaux récentes, jusqu'à une limite de 20% d'eau récente. Le suivi temporel de la dynamique des communautés d'un aquifère avant et au début de la recharge a montré dans la zone altérée des conditions chimiques très fluctuantes et une communauté microbienne très changeante mais toujours constituée de nombreux potentiels dénitrifiants. Dans la zone fracturée, la communauté dominée par les Gallionellaceae est relativement stable, malgré des changements chimiques ponctuels substantiels et un degré de mélange transitoire important (jusqu'à 60% d'eau récente) au début de la recharge. Les Gallionellaceae semblent donc capables de résister à des changements ponctuels et importants des conditions chimiques. Les eaux souterraines de la partie profonde des aquifères, bien qu'isolées, restent relativement connectées à la surface ce qui permet probablement le maintien de l'écosystème microbien profond. / Hard-rock aquifers are heterogeneous geological structure very widespread in Britany that have the property to store groundwater. These aquifers are often made of a weathered zone and a fractured zone. The weathered zone is a rather thin layer close to the surface and is constituted of weathered rocks submerged in groundwater. In this zone, groundwater circulates rapidly from the upper parts of the watershed to the aquifer outlet, thus shows short groundwater residence time (< 20y) and is often polluted by nitrates. The fractured zone is located deeper and is thicker. It is composed of fresh rocks crossed by fractures in which groundwater exclusively flows with a very slow velocity, thus groundwater residence time in this zone is rather long (>40 y). In the fractured zone, groundwater is much more mineralized and often rich in iron, in Britany. The differences of flow velocities in the weathered and the fractured zones are responsible for contrasted chemical conditions in these two zones, but the influence of groundwater flow velocity on the microbial ecosystem in groundwater remains largely unexplored. This work shows hydrologic circulations influence the microbial community structuration in hard-rock aquifer groundwater at regional and local scales. Position of a groundwater along a hydrologic flowpath or a “hydrological loop” directly controls microbial community structure through the control of the successively available electron donors and acceptors. The analyzed microbial communities show a predominance of Betaproteobacteria. In recent groundwater (< 20y) thus particularly in the weathered zone, Betaproteobacteria are mainly Comamonadaceae and Oxalobacteraceae, which are generalists able to do denitrification. In old and isolated groundwater (> 40y) thus particularly in the fractured zone, Betaproteobacteria are mainly Gallionellaceae, which are microaerophilic iron-oxidizer. The predominance of Gallionellaceae in the fractured zone suggests a deep ecosystem based on iron oxidation. However, this process implies a minimal input of oxygen in the deeper part, for instance via mixing with recent oxygenated groundwater. Proportion of Gallionellaceae in the different analyzed groundwater shows a positive correlation with the degree of mixing between old and recent groundwater, up to a limit of 20% of recent groundwater. The temporal microbial community dynamics in a single aquifer, before and during the beginning of recharge, demonstrated in the weathered part very fluctuant chemical conditions and a shifting microbial community that remains always composed of numerous potential denitrifiers. In the fractured part, microbial community is dominated by Gallionellaceae and remains rather stable, despite the punctual but substantial changing of the chemical conditions and degree of mixing (up to 60% of recent groundwater) at the beginning of the recharge. Gallionellaceae seem thus able to resist to important and punctual chemical conditions changings. Groundwater in the deeper part of aquifers, even isolated, remains relatively connected to surface, likely allowing the deep microbial ecosystem to maintain.

This diploma thesis deals with the conceptual knowledge of primary school pupils about field ecosystems. In the analyzed textbooks, ecological relations are represented only to a limited extent. They are not sufficiently explained or practiced during lessons. Test questions focus on a complex understanding of field ecosystem matters; they test the extent of understanding of relationships between organisms and their environment, between different organisms, and the extent to which field ecosystems are affected by human activity. Analysis results reflect the level of the pupils' knowledge regarding field ecosystem interrelations. Test questions designed by the author of the thesis examine fourth grade primary school pupils and their understanding of relationships between organisms and their environment, as well as relationships between different organisms. Results show that pupils understand relationships between organisms and their environment better than relationships between different organisms and the effects of human activity on field ecosystems. These differences are, however, not significant. In general, the research shows that fourth grade pupils do not understand field ecosystem relationships in an entirely correct way.

<p></p><p></p><p>Peatlands are the most efficient natural carbon sink on the planet. They are the most carbon-intensive storages than any other vegetation types. However, recent studies indicate that global peatlands can potentially release 6% of the global soil carbon into the atmosphere when they are drained or deforested. They cover only about 3% of the total global land area, but sequester over 30% of the Earth’s soil organic carbon. Peatlands in northern mid-to-high latitudes (45°-90°N) occupy ~90% of the global peatland area and account for ~80% of the total global peat organic carbon stock. Those peatlands are mainly located in Canada, Russia, and the USA. Peatlands in tropical regions cover ~10% of the global peatlands area and store 15-19% of the global peat organic carbon. They are mainly distributed in Southeast Asia and South and Central America. The temperature at the global scale has been rising since the middle of the last century and has accelerated during the last 40 years and the warming will continue in this century. The large storage of soil organic carbon within the peatlands can significantly respond to the changing climate by varying the roles between their carbon sink (from atmosphere to soil) and source (from soil to atmosphere) activities. This dissertation focuses on quantifying the soil organic carbon dynamics in North America and South America using mechanistically-based biogeochemistry models. </p><p></p><p>Peatlands in Alaska occupy 40 million hectares and account for ~10% of the total peatland area in northern mid-to-high latitudes. The regional soil organic carbon dynamics and its response to climate are still with large uncertainty. Most of the studies on peatlands to date are based on short-term site-level observation. This dissertation first used an integrated modeling framework that coupled the dynamics of hydrology, soil thermal regime, and ecosystem carbon and nitrogen to quantify the long-term peat carbon accumulation in Alaska during the Holocene. Modeled hydrology, soil thermal regime, carbon pools and fluxes and methane emissions were evaluated using long-term observation data at several peatland sites in Minnesota, Alaska, and Canada. The model was then applied for a 10,000-year (15 ka to 5 ka; 1 ka = 1000 cal yr before present) simulation at four peatland sites. The model simulations matched the observed carbon accumulation rates at fen sites during the Holocene (R^2= 0.88, 0.87, 0.38 and -0.05 for four sites respectively using comparisons in 500-year bins from 15 ka to 5 ka). The simulated (2.04 m) and observed peat depths (on average 1.98 m) also compared well (R^2 = 0.91). The early Holocene carbon accumulation rates, especially during the Holocene thermal maximum (HTM) (35.9 g 〖C m〗^(-2) yr^(-1)), were estimated up to 6-times higher than the rest of the Holocene (6.5 g 〖C m〗^(-2) yr^(-1)). It suggested that high summer temperature and the lengthened growing season resulted from the elevated insolation seasonality, along with wetter-than-before conditions might be major factors causing the rapid carbon accumulation in Alaska during the HTM. The sensitivity tests indicated that, apart from climate, initial water-table depth and vegetation canopy were major drivers to the estimated peat carbon accumulation. </p><p></p><p>To further quantify the regional long-term soil organic carbon accumulation rates and the current carbon stocks in Alaska, the second part of my research focused on quantifying the soil organic carbon accumulation in multiple Alaskan terrestrial ecosystems over the last 15,000 years for both peatland and non-peatland ecosystems. Comparable with the previous estimates of 25-70 Pg carbon (C) in peatlands and 13-22 Pg C in non-peatland soils within 1-m depth in Alaska using peat core data, our model estimated a total SOC of 36-63 Pg C at present, including 27-48 Pg C in peatland soils and 9-15 Pg C in non-peatland soils. Current living vegetation stored 2.5-3.7 Pg C in Alaska with 0.3-0.6 Pg C in peatlands and 2.2-3.1 Pg C in non-peatlands. The simulated average rate of peat soil C accumulation was 2.3 Tg C yr^(-1) with a peak value of 5.1 Tg C yr^(-1) during the Holocene Thermal Maximum (HTM) in the early Holocene, four folds higher than the average rate of 1.4 Tg C yr^(-1) over the rest of the Holocene. The accumulation slowed down, or even ceased, during the neo-glacial climate cooling after the mid-Holocene, but increased again in the 20th century. The model-estimated peat depths ranged from 1.1 to 2.7 m, similar to the field-based estimate of 2.29 m for the region. The changes in vegetation and their distributions were the main factors to determine the spatial variations of SOC accumulation during different time periods. Warmer summer temperature and stronger radiation seasonality, along with higher precipitation in the HTM and the 20th century might have resulted in the extensive peatland expansion and carbon accumulation. </p><p>Most studies on the role of tropical peatlands have focused on Indonesian peatlands. Few have focused on the Amazon basin, where peatlands remain intact and have been a long-term carbon sink. To address the problem, my third study quantified the carbon accumulation for peatland and non-peatland ecosystems in the Pastaza-Marañon foreland basin (PMFB), the most extensive peatland complex in the Amazon basin from 12,000 years before present to 2100 AD. Model simulations indicated that warming accelerated peat carbon loss while increasing precipitation accelerated peat carbon accumulation at millennial time scales. The uncertain parameters and spatial variation of climate were significant sources of uncertainty to modeled peat carbon accumulation. Under warmer and presumably wetter conditions over the 21st century, the warming effect on increasing peat carbon loss might overwhelm the wetter effect on increasing peat carbon accumulation. Peat soil carbon accumulation rate in the PMFB slowed down to 7.9 (4.3~12.2) g C m^(-2) yr^(-1) from the current rate of 16.1 (9.1~23.7) g C m^(-2) yr^(-1) and the region might turn into a carbon source to the atmosphere at -53.3 (-66.8~-41.2) g C m^(-2) yr^(-1) (negative indicates source), depending on the level of warming. Peatland ecosystems showed a higher vulnerability than non-peatland ecosystems as indicated by the ratio of their soil carbon density changes (change of soil carbon/existing soil carbon stock) ranging from 3.9 to 5.8). This was primarily due to larger peatlands carbon stocks and more dramatic responses of their aerobic and anaerobic decompositions in comparison with non-peatland ecosystems under future climate conditions. Peatland and non-peatland soils in the PMFB might lose up to 0.4 (0.32~0.52) Pg C by 2100 AD with the largest loss from palm swamp. The carbon-dense Amazonian peatland might switch from a current carbon sink into a source in the 21st century.</p><p>Peatlands are important sources and sinks for greenhouse gases (carbon dioxide and methane). Their carbon (C) balance between soil and atmosphere remains unquantified due to the large data gaps and uncertainties in regional peat carbon estimation. My final study was to quantify the C accumulation rates and C stocks within North America peatlands over the last 12,000 years. I find that 85-174 Pg C have been accumulated in North American peatlands over these years including 0.37-0.76 Pg C in subtropical peatlands in this region. During the 10- 8 ka period, the warmer and wetter conditions might have played an important role in stimulating peat C accumulation by enhancing plant photosynthesis. The enhanced peat decomposition due to warming through the Holocene slows down carbon accumulation in the region.</p><div><br></div><p><br></p>

Nas últimas décadas, tem-se observado uma expressiva queda da qualidade ambiental e perda de biodiversidade nos ecossistemas aquáticos em função de múltiplos impactos advindos de atividades antrópicas. Dessa forma, considerando-se que a estrutura das comunidades pode ser alterada por tais perturbações, diversos métodos têm sido propostos para avaliações da qualidade nesses ecossistemas, destacando-se, entre eles, o uso dos macroinvertebrados bentônicos. Alguns estudos empregando estes indicadores defendem a sua identificação ao nível genérico por fornecer maior número de informações, resultar em classificações ambientais mais confiáveis e apresentar melhor capacidade de distinção entre os pontos, quando comparado aos níveis de resolução mais abrangentes. Entretanto, na maioria dos trabalhos a identificação desse grupo restringe-se ao nível de família, principalmente em função da economia nos recursos despendidos durante a identificação o que não se justifica caso este nível não retenha informações suficientes para que os objetivos sejam alcançados. Neste trabalho, esse conflito foi avaliado através da comparação de avaliações biológicas decorrentes da aplicação de índices estruturais baseados na identificação de Chironomidae, ao nível genérico com o de sub-família/tribo. Foram utilizadas amostras de organismos bentônicos, bem como os dados físicos, químicos e microbiológicos coletados em sete pontos de amostragem que fizeram parte de vários projetos da CETESB (Companhia de Tecnologia de Saneamento Ambiental), conduzidos ao longo de diferentes anos e classificados, de acordo com o ICBRIO (Índice da Comunidade Bentônica para rios) em ambientes de qualidade péssima, ruim, regular, boa e ótima. As coletas foram padronizadas em relação ao período (inverno) e ao tipo de hábitat amostrado (margem deposicional). As amostras foram obtidas em triplicata com o auxílio de pegadores (Ponar e Petersen modificado) e o material selecionado em rede com abertura de malha 0,5 mm. A contagem e identificação dos organismos foram feitas com o auxílio de estereomicroscópio, microscópio óptico e bibliografia especializada. Para definir o gradiente de qualidade, as variáveis ambientais foram submetidas a uma Análise de Agrupamento pelo método de Ward, empregando-se a Distância Euclidiana Simples. Já os valores de densidade foram reunidos em uma matriz de distância de Bray-Curtis agrupada pelo método de média de grupo não ponderada a fim de verificar o grau de similaridade entre os pontos e se o nível de identificação taxonômica interfere nas associações formadas. Com o intuito de verificar a sensibilidade do nível taxonômico do dado ao gradiente de qualidade ambiental, bem como testar a possível influência do refinamento taxonômico na sensibilidade do ICBRIO foram empregadas as métricas Riqueza, Diversidade de Shannon-Wiener, Índice de Comparação Seqüencial, Dominância de Grupos Tolerantes e Riqueza de Táxons Sensíveis. Tendo por objetivo o diagnóstico das condições ambientais, com redução de custos e tempo de manipulação das amostras, mas com informações relevantes que subsidiem os tomadores de decisão, o presente trabalho vem descartar o emprego do nível de resolução genérico na identificação das larvas de Chironomidae. Os resultados expostos confirmaram a aplicabilidade do ICBRIO com a identificação deste grupo aos níveis de sub-família/tribo na avaliação da qualidade ambiental, demonstrando não serem necessárias eventuais alterações nos seus moldes. / In the last decades, it has been observed an expressive deterioration of the environmental quality and biodiversity loss in the aquatic ecosystems as function of anthropogenic activities. Considering that communities' structure can be altered by such disturbances, several methods have been proposed for quality assessment in those ecosystems, standing out, among them, the use of the benthic macroinvertebrates. Some studies using these indicators defend the generic level identification as they supply more information, result in more reliable environmental classifications and present better distinction capacity among sites, when compared to broader levels. However, in most of the works the identification of this group is limited to the family level, mainly due to resources saving during the identification, which is not justified in the case this level misses information to classification aims. In this work, comparison of current biological evaluations through Chironomidae identification structural indexes at the generic level with the one at sub-family/tribe was evaluated. Benthic organisms samples, as well as physical, chemical and microbiological data were collected in seven sampling sites, from several projects taken along different years by CETESB (Company of Technology of Environmental Sanitation), which classified the environment as, according to ICBRIO (Benthic Community Index for rivers), worst, bad, regular, good and excellent quality. The collections were standardized to winter period and to type of sample habitat (depositional river margin). Triplicates were obtained with modified Ponar and Petersen grabs on retained material by 0.5mm-mesh sieve. Counting and identification based on specialized literature were done with the stereomicroscope, and optical microscope. To define the quality gradient, the environmental variables were submitted to a Cluster Analysis by the Ward method, using the simple Euclidean Distance. Density values were lumped on a Bray-Curtis distance matrix by the Unweighted Pair Group method in order to verify the similarity degree among the points and the interferences of taxonomic identification level on the formed associations. Aiming to check the sensibility of the data taxonomic level to the environmental quality gradient, as well as to test the possible influence of taxonomic refinement in the ICBRIO's sensibility, several metrics (Richness, Shannon-Wiener Diversity Index, Sequential Comparison Index, Dominance of Tolerant Groups and Richness of Sensitive Taxa) were used. Seeking the diagnosis of the environmental conditions, reducing costs and manipulation time of the samples, but keeping relevant information to subsidize the policy managers, the present work discards the need of the generic resolution level in the Chironomidae larvae identification. The exposed results confirmed the applicability of ICBRIO with the identification of this group at sub-family/tribe levels on the environmental quality assessment, demonstrating no need of eventual modification in the method.

Two sympatric dolphin species, Stenella frontalis and Tursiops truncatus, resident to Little Bahama Bank, Bahamas were found to mostly forage independent of one another, but occasionally foraged in mixed groups. Analysis of over 20 years of data revealed the degree of overlap to be minimal with spatially distinct regions identified for both species, environmental segregation based on depth, bottom type, temperature, and time of day. Results based on observational data indicated significant differences in group size and selected prey. For S. frontalis, lactating females had the most distinct diet, which differed from that of non-reproductively active (NRA) females. Pregnant females had ambiguous prey use results, but diet differences were revealed through nutritional analysis. Lactating females had a higher intake of all nutrients (% moisture, % lipid, % protein, and calories) than pregnant females but lower than NRA females. Mother and calf pairs selected prey for caloric and moisture values. The influence of calves on foraging groups was reflected through discrete differences in all nutrients. Males and females appeared to select the same major prey, but female prey use was much more diverse. / by Christopher R. Malinowski. / Thesis (M.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

A confounding factor for sea level rise (SLR) is that it has a slow, steady creep, which provides a false sense for coastal communities. Stresses caused by SLR at today’s rate are more pronounced in southeastern Florida and as the rate of SLR accelerates, the exposure areas will increase to a point where nearly all the state’s coastal infrastructure will be challenged. The research was conducted to develop a method for measuring the impact of SLR on the City of West Palm Beach (City), assess its impact on the stormwater system, identify vulnerable areas in the City, provide an estimate of long-term costs of improvements, and provide a toolbox or strategies to employ at the appropriate time. The assessment was conducted by importing tidal, groundwater, topographic LiDAR and infrastructure improvements into geographic modeling software and performing analysis based on current data. The data revealed that over $400 million in current dollars might be needed to address stormwater issues arising from SLR before 2100. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

O nitrogênio é o quinto elemento mais abundante em nosso sistema solar, é essencial para a síntese de ácidos nucleicos e proteínas, os dois polímeros mais importantes da vida. Apesar da importância do nitrogênio e sua abundância na atmosfera, o N2 é praticamente inerte; assim, as formas de nitrogênio inorgânico fixados mais comuns são os íons nitrato e amônio que muitas vezes limitam a produtividade primária nos ecossistemas marinhos e terrestres. Uma biosfera ativa requer a incorporação do nitrogênio em moléculas biológicas por meio da fixação de nitrogênio, um processo no qual os domínios em procarióticos Bacteria e Archaea reduzem gás nitrogênio em amônia. Porém, a maioria dos organismos não pode fixar nitrogênio, mas sim obtê-lo na forma de nitrogênio orgânico a partir do ambiente, ou a partir da redução do nitrato. O amônio é retornado para o ambiente quando os organismos morrem e isto depende da presença do oxigênio nestes locais. Na presença do oxigênio, o amônio é oxidado em nitrato, numa via conhecida como nitrificação. Na ausência de oxigênio, o nitrato é utilizado por muitos microrganismos como um receptor de elétrons, como na redução dissimilatória de nitrato a amônia (DNRA), acoplada à oxidação anaeróbica de carbono orgânico; o nitrato pode ser convertido em gás dinitrogênio pela desnitrificação, ou ainda uma via alternativa pode transformar o nitrogênio fixado em N2, realizada por um grupo de bactérias conhecido como planctomycetes, onde a oxidação do amônio é acoplada a redução de nitrato, no processo chamado anammox. Neste trabalho de tese foi realizada a avaliação do ciclo do nitrogênio, buscando entendimento de três vias de transformação deste elemento. Neste sentido, estas vias foram avaliadas quanto as suas taxas de ocorrência, com uso incubações do sedimento de manguezais e nitrogênio marcado, como também por meio da identificação de genes funcionais envolvidos nestes três processos, por meio de pirosequenciamento. O grupo Planctomycetes ainda pode ser estudado utilizando a hibridização com sonda fluorescente in situ FISH. Os resultados indicam a presença marcante de genes identificados como parte da via desnitrificação, assim como as taxas de incubação observadas para esta via foram muito expressivas quando comparadas com as taxas obtidas para o processo anammox e DNRA. Os resultados obtidos com as análises metagenômicas e com a técnica FISH sustentam os resultados obtidos com as incubações. Pode-se observar que a filogenia sugere a tendência do agrupamento com organismos planctomycetes não descritos como responsáveis pelo processo anammox. Por meio da técnica FISH pode-se confirmar a detecção destas bactérias e visualizar sua menor presença nos manguezais amostrados, quando comparadas às bactérias totais encontradas nestas amostras. / Nitrogen is the fifth most abundant element in our solar system, essential for the synthesis of nucleic acids and proteins, one of the most important polymers of life. Despite the importance of nitrogen and its overwhelming abundance in the atmosphere, N2 is practically inert, so the most commom forms of inorganic nitrogen fixed are nitrate and ammonium ions, which often limit primary productivity in marine and terrestrial ecosystems. An active biosphere requires the incorporation of nitrogen in biological molecules through nitrogen fixation, a process in which domains Archaea and Bacteria reduce nitrogen gas into ammonia. The most organisms can\'t fix nitrogen, but they can get it in inorganic nitrogen form from the environment or from the reduction of nitrate. The ammonia is returned to environment when organisms die and it depends on the presence of oxygen at these sites. In the presence of oxygen, ammonia is oxidized to nitrate, in a way known as nitrification, and in the absence of oxygen, the nitrate being used by many microbes as an electron acceptor, such as dissimilatory nitrate reduction to ammonia (DNRA), coupled to anaerobic oxidation of organic carbon. The nitrate can be converted to dinitrogen gas by denitrification, or an alternative route can turn fixed nitrogen in N2, performed by a bacteria group known as Planctomycetes, where oxidation is coupled to the ammonium nitrate reduction, in a process called anammox. In this work, with mangrove sediments from Bertioga city, State of São Paulo, the evaluation of these three pathways of nitrogen transformation was performed as their rates of occurrence, with incubations with labeled nitrogen, as well as through the identification of functional genes involved in these three cases, by pyrosequencing. The group Planctomycetes can also be studied using the hybridization probe FISH fluorescence in situ. The results show the strong presence of genes identified as part of the denitrification pathway, as well as the rates observed for incubation of this pathway were very significant when compared with the rates obtained for the process anammox and DNRA. The results obtained from the metagenomic analyze and the FISH technique support the results obtained with incubations. It can be observed that the trend suggests the phylogeny of the organisms group with Planctomycetes not described as responsible for anammox process. Through the FISH technique, it was possible to confirm the detection of these bacteria and view its reduced presence in mangrove sampled compared to total bacteria found in these samples.

As samambaias do gênero Pteridium caracterizam-se pelas largas frondes e por um sistema de rizomas subterrâneos que possibilita sua rápida expansão. Apresentam elevada produção de biomassa ao longo do ano, que aumenta a incidência de incêndios, e ainda liberam substâncias químicas consideradas alelopáticas. Atualmente, são conhecidas como plantas-problema, pois vêm se expandindo e ocupando grandes áreas em diversas partes do mundo, causando impacto econômico e ecológico. Nesse contexto, este estudo teve por objetivo geral a compreensão do impacto da invasão por Pteridium arachnoideum sobre a vegetação de cerrado e a elucidação dos mecanismos por meio dos quais vem sendo lentamente revertido o processo de invasão na área de estudo. Para tanto, analisamos áreas de cerradão invadidas há mais de quatro décadas na Estação Ecológica de Assis (EEcA), no sudoeste do estado de São Paulo. Analisamos a composição florística e estrutura da comunidade em uma área invadida dentro da EEcA. Avaliamos os componentes do estrato arbóreo e regenerante da comunidade, a fim de verificar quais as espécies que conseguiram ultrapassar as barreiras físicas e químicas impostas pela presença da samambaia. Para tanto, comparamos a vegetação da área invadida com uma área adjacente não invadida, com ambiente e histórico de perturbações semelhantes. Utilizamos 100 pontos quadrantes para amostragem da composição florística e, para caracterização da estrutura da comunidade, alocamos 15 parcelas de 10 m x 30 m para amostrar o estrato superior, dentro das quais foram instaladas sub-parcelas de 2 m x 30 m para o estrato intermediário e de 2 m x 2 m para o estrato inferior. Medimos a cobertura das copas das árvores dentro das parcelas e estimamos a porcentagem de cobertura do solo por Pteridium. As espécies que conseguiram ocupar a área no início da invasão são tolerantes à sombra e com ritmo de crescimento rápido, características que possibilitaram que tais espécies ultrapassassem a barreira de samambaia e se estabelecessem na área. Já as espécies do estrato inferior se assemelham às da área não invadida, indicando que está havendo uma substituição das espécies na comunidade vegetal. A baixa densidade das árvores na área invadida diminui a competição entre os indivíduos, que, por sua vez, investem em aumento de tamanho, sendo consideravelmente maiores do que as árvores do cerradão não invadido. Essas árvores, que formam o estrato arbóreo atualmente, estão facilitando a regeneração natural de espécies arbóreas nativas e, assim, revertendo, lentamente, o processo de invasão. Testamos quais variáveis, relacionadas às funções ecológicas e aspectos estruturais das árvores de grande porte que se estabeleceram nas áreas invadidas, estão favorecendo as plantas em regeneração sob suas copas. Para tanto, amostramos os indivíduos maiores que 50 cm sob a copa de árvores sistematicamente selecionadas, segundo atributos funcionais e estruturais. Verificamos que as árvores que possuem copas mais densas e perenifólias apresentaram mais regenerantes sob suas copas. A resiliência característica do cerrado tem possibilitado que as áreas invadidas consigam se recuperar, podendo se assemelhar futuramente às áreas de cerradão da EEcA, porém muito lentamente. Ações de manejo que almejam a restauração dessas áreas mais rapidamente devem focar seus esforços na eliminação do Pteridium e/ou na introdução de espécies que possuam as características das árvores que atuam como facilitadoras da regeneração. / The genus Pteridium comprises bracken species recognized by large fronds and a rhizome system that allows their fast expansion. Bracken presents an elevated biomass production throughout the year, that increases fire occurrence and release chemical compounds that are considered allelopathic. Nowadays, species of the genus Pteridium are well known as problem-species, due to their expansion and occupation of large areas around the world, causing great economic and ecological impacts. Aiming at the comprehension of bracken invasion over cerrado vegetation, we studied its impact over the plant community and, also, the slow natural regeneration process of cerrado recovery after invasion. We analyzed savanna woodland areas that have been invaded for over four decades, at Assis Ecological Station (EEcA), in southwestern São Paulo State. We analyzed the floristic composition and the plant community structure in an invaded area, compared to a non invaded patch of savanna vegetation. Components of the arboreal and regeneration strata were analyzed, in order to verify which species managed to pass by the physical and chemical barrier imposed by bracken. We assessed 100 points to assemble the floristic composition, using the quarter method, and for the community structure we used 15 plots of 10 m x 30 m to assemble the superior strata. The intermediate layer was assessed by sub-plots of 2 m x 30 m and the inferior strata using 2 m x 2 m sub-plots. We measured the canopy cover and also bracken cover inside the plots. The arboreal species first occupying the invaded area are shadow tolerant and fast growing, attributes which allowed them to overtake the bracken layer and establish. Nowadays, the invasive species has been replaced by a high number of arboreal species, the inferior strata being floristically similar to the area not invaded. The low density of adult trees in the invaded area reduce the competition among individuals that end up investing in growth, with greater size compared to those trees in the non invaded area. These large trees function as nurse trees, facilitating other species to establish under their canopies. We tested which variables related to the ecological functions and tree structure are favouring the understory, in order to comprehend the ecological processes and interactions that regulate the assembly rules of the invaded community being recovered. We assembled all individuals from arboreal species over 50 cm high growing under the projection of nurse trees canopy. These nurse trees were systematically selected, for the basis of functional and structural attributes. Understory density and richness were higher under trees with dense and permanent shadow, and that was the attribute better explaining the recovery process. The high resilience of savanna have helped the recovery of invaded areas. This process, however, has been very slow. Interventions whiling to restore those areas should be focused on bracken eradication and/or introduction of those species that can facilitate the natural regeneration.

Externalities caused by human transformations in ecosystems structure and functioning has been threatening environmental quality and social welfare in all socioecological systems, including coastal zones. Environmental Impact Assessment (EIA) is an instrument widely used to evaluate the feasibility of developments and projects that can potentially provoke changes in biophysical-human environment. However, EIA generic and fragmented approach has not properly been considering people and environmental particularities, such processes and benefits to society, in decision making. Ecosystem-Based Management recently emerged as a strategy that can qualify EIA, by embracing ecosystem processes and services (ES), human dimensions, social engagement and Local, Traditional and Scientific Ecological Knowledge. Using a case study of a contested Port expansion in São Sebastião, São Paulo, Brazil, that endangered the sustainability of an adjacent bay (Araçá Bay), we selected analytical categories comprising different stakeholders, ecosystem services and disturbances scenarios to understand the role of EBM in coastal EIA. We presumed that stakeholders with deeper relationships with the place could provide more comprehensive assessments about changes in the availability of main local ES, as a result of greater sense of place, access to different sources of knowledge and opportunities to social participation. Also, an EBM approach would provide a more robust, i.e., a wider and more integrated assessment of impacts in the provision of the ES than the Environmental Impact Study (EIS) of the port expansion. We performed in-depth interviews with four different groups of stakeholders and analyzed their speeches with discourse analysis and statistical inquiries to assess ES scores of occurrences in current (Two-way ANOVA) and disturbances scenarios (Repeated measures ANOVA and PERMANOVA), besides their main argumentation patterns. We compared these results with the port expansion EIS to assert to robustness of the method. The groups had different perceptions from each other, which depended on the scenario and ES evaluated. We corroborated the hypotheses: groups\' closer, deeper and more engaged relationships with the place had more comprehensive assessments of changes in the ES; and stakeholders perceptions reflected trade-offs of the local urban conflicts, providing a higher variety and more integrated assessments of impacts than the Environmental Impact Study of the Port expansion. The diversity of forms of knowledge, behaviors and functions, in temporal and spatial scales, proved to be valuable for the groups\' assessments of resource and the territory, and the choice of the analytical categories was fundamental to consolidate the understanding of local socioecological processes. We concluded that the method tested was efficient and respected the intrinsic variability of coastal zones and its function as a socioecological system to assert that EBM has a great potential to improve the effectiveness of EIA. / As externalidades causadas por transformações humanas na estrutura e funcionamento dos ecossistemas têm ameaçado a qualidade ambiental e o bem-estar social em todos os sistemas socioecológicos, incluindo as zonas costeiras. A Avaliação de Impacto Ambiental (AIA) é um instrumento amplamente utilizado para avaliar a viabilidade de empreendimentos e projetos que podem provocar potenciais mudanças no ambiente biofísico-humano. No entanto, a abordagem genérica e fragmentada da AIA não tem devidamente considerado as pessoas e as particularidades ambientais, como os processos e valores sociais, na tomada de decisões. A Abordagem Baseada em Ecossistemas (ABE) surgiu recentemente como uma estratégia que pode qualificar a AIA, abrangendo processos e serviços ecossistêmicos (SE), dimensões humanas, engajamento social e Conhecimento Ecológico Local, Tradicional e Científico. Utilizando um estudo de caso de uma contestada ampliação portuária em São Sebastião, São Paulo, que ameaçou a sustentabilidade de uma baía adjacente (a Baía de Araçá), selecionamos categorias analíticas que compreendem diferentes stakeholders (ou principais atores), serviços ecossistêmicos e cenários de perturbações para entender o papel da ABE na AIA costeira. Presumimos que os stakeholders com relações mais profundas com o local poderiam fornecer avaliações mais abrangentes sobre mudanças na disponibilidade dos principais SE locais, como resultado de maior senso de pertencimento, acesso a diferentes fontes de conhecimento e oportunidades para participar socialmente. Além disso, assumimos que a ABE proporcionaria uma AIA mais robusta, ou seja, com uma perspectiva mais ampla e mais integrada dos impactos na provisão dos SE do que Estudo de Impacto Ambiental da expansão portuária. Realizamos entrevistas em profundidade com quatro grupos diferentes de stakeholders e analisamos o conteúdo por meio de análise de discurso e testes estatísticos para avaliar as ocorrências dos SE no cenário atual (ANOVA de duas vias) e nos cenários de perturbações (ANOVA de medidas repetidas e PERMANOVA), além dos principais padrões de argumentação dos stakeholders. Comparamos esses resultados com o Estudo de Impacto Ambiental da ampliação do Porto para afirmar a robustez do método. Os grupos apresentaram diferentes percepções uns dos outros, o que dependeu do cenário e do SE avaliado. Nós corroboramos as hipóteses: grupos com relações mais próximas, mais profundas e mais comprometidas com o local tiveram avaliações mais abrangentes das mudanças dos SE; e as percepções dos stakeholders refletiram os trade-offs (ou qualidade, aspecto) dos conflitos urbanos locais, proporcionando avaliações mais variadas e integradas de impactos do que o Estudo de Impacto Ambiental da expansão portuária. A diversidade de formas de conhecimento, comportamentos e funções, em escalas temporais e espaciais, se provaram valiosas para avaliações dos grupos sobre os recursos e o território, e a escolha das categorias analíticas foi fundamental para consolidar a compreensão dos processos socioecológicos locais. Concluímos que o método testado foi eficiente e respeitou a variabilidade intrínseca das zonas costeiras e sua função como um sistema socioecológico, o que afirmou que a ABE tem um grande potencial para melhorar a eficácia da AIA.