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Consumer-resource interactions are the basic building blocks of every food web. In spite of being a central research theme of longstanding interest in ecology, the mechanisms governing the stability and persistence of consumer-resource interactions are still not entirely understood. In particular, theoretical predictions on consumer-resource stability along gradients of temperature and nutrient enrichment diverge widely and are sometimes in conflict with empirical results. In this thesis I address these issues from the angle of the functional response, which describes a consumer’s feeding rate as a function of resource density. Specifically, I explore mechanistic, nutrient-based consumer-resource interaction models with respect to the influence of feeding behavior (the shape of the functional response), environmental temperature, nutrient enrichment, and resource quality on consumer-resource stability and persistence. In order to parameterize these models I performed extensive laboratory experiments with pairs of freshwater pelagic algae and grazers of the genus Daphnia, which are widespread, ecologically important model organisms. I found a sigmoidal type III functional response in every studied Daphnia-algae species pair. The exact form of its shape is described by an exponent b which is determined by fitting functional response models to the experimental data. A high value of b can stabilize consumer-resource systems under the otherwise destabilizing influence of nutrient enrichment, as predicted by a novel stability criterion relating b to the consumer’s prey handling time, food conversion efficiency and mortality. Estimated parameter values and, consequently, stability predictions are sensitive to the method of parameter estimation, and I propose a new estimation procedure that minimizes parameter uncertainty. Because many consumers’ feeding rates depend on temperature, warming is expected to strongly affect food web stability. In functional response experiments over a broad temperature gradient, I found that the attack rate coefficient and the maximum ingestion rate of Daphnia are hump-shaped functions of temperature. Moreover, the functional response exponent increases with warming towards stronger type III responses. Plugging these findings into a nutrient-based consumer-resource model, I found that predator persistence is a U-shaped function of temperature in nutrient enrichment-temperature space. Enrichment easily turns the system unstable when the consumer has a type II response, whereas a type III response opens up a large region of stability at intermediate, for the consumer optimal, temperatures. These findings reconcile seemingly conflicting results of earlier studies of temperature effects on consumer-resource dynamics, which can be mapped as special cases onto the enrichment-temperature space. I finally demonstrate the utility of three key model ingredients - temperature dependence of rate parameters, a mechanistic description of the dynamics of algal resources, and a type III functional response in Daphnia - by successfully implementing them in the description and explanation of phytoplankton-Daphnia dynamics in a mesocosm experiment exploring effects of warming on the spring succession of the plankton.

Anthropogenic activities perturb the global carbon and nitrogen cycle with large implications for the earth’s climate. Land use activities deliver excess carbon and nitrogen to aquatic ecosystems. In the boreal biome, this is mainly due to forestry and atmospheric deposition. Yet, impacts of these anthropogenically mediated inputs of carbon and nitrogen on the processing and emissions of greenhouse gases from recipient streams and lakes are largely unknown. Understanding the ecosystem-scale response of aquatic greenhouse gas cycling to land use activities is critical to better predict anthropogenic effects on the global climate system and design more efficient climate change mitigation measures. This thesis assesses the effects of forest clearcutting and nitrate enrichment on greenhouse gas emissions from boreal inland waters. It also advances methods to quantify sources and sinks of these emissions. Short-term clearcut and nitrate enrichment effects were assessed using two whole-ecosystem experiments, carried out over four years in nine headwater catchments in boreal Sweden. In these experiments, I measured or modeled air-water fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), combining concentration, ebullition and gas-transfer velocity measurements in groundwater, streams and lakes. By using Swedish national monitoring data, I also assessed broad-scale effects of forest clearcutting by relating CO2 concentrations in 439 forest lakes to the areal proportion of catchment forest clearcuts. To improve quantifications of CO2 sources and sinks in lakes, I analyzed time series of oxygen concentrations and water temperature in five lakes on conditions under which whole-lake metabolism estimates can be inferred from oxygen dynamics given the perturbing influence of atmospheric exchange, mixing and internal waves. The experiments revealed that aquatic greenhouse gas emissions did not respond to nitrate addition or forest clearcutting. Importantly, riparian zones likely buffered clearcut-induced increases in groundwater CO2 and CH4 concentrations. Experimental results were confirmed by monitoring data showing no relationship between CO2 patterns across Swedish lakes and clearcut gradients. Yet, conclusions on internal vs. external CO2 controls largely depended on whether spatially or temporally resolved data was used. Partitioning CO2 sources and sinks in lakes using time series of oxygen was greatly challenged by physical transport and mixing processes. Conclusively, ongoing land use activities in the boreal zone are unlikely to have major effect on headwater greenhouse gas emissions. Yet, system- and scale specific effects cannot be excluded. To reveal these effects, there is a large need of improved methods and design of monitoring programs that account for the large spatial and temporal variability in greenhouse gas dynamics and its controls by abiotic and biotic factors.

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This thesis combines solid-state nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD), chemical synthesis, isotopic enrichment and density-functional theory (DFT) calculations to provide insight into a number of microporous materials. The first class of materials studied is metal-organic frameworks (MOFs), where the presence of paramagnetic ions has a range of effects on the ¹³C NMR spectra, depending on the nature of the ligand-metal interactions. For the Cu²⁺-based MOFs, HKUST-1 and STAM-1, the assignment of the NMR spectra is non-intuitive, and unambiguous assignment requires specific ¹³C labelling of the organic linker species. It is shown that ¹³C NMR spectra of these two MOFs could act as a sensitive probe of the nature of “guest” molecules bound to the Cu²⁺. The second class of materials is aluminophosphates (AlPOs). It is shown that, using a series of relatively simple linear relationships with the crystal structure, the NMR parameters calculated by DFT (with calculation times of several hours) can be predicted, often with experimentally-useful accuracy, in a matter of seconds using the DIStortion analysis COde (DISCO), which is introduced here. The ambient hydration of the AlPO, JDF-2, to AlPO-53(A) is shown to occur slowly, with incomplete hydration after ~3 months. The resulting AlPO-53(A) is disordered and some possible models for this disorder are investigated by DFT. The final class of materials is gallophosphates (GaPOs), particularly GaPO-34 and related materials. The two as-prepared forms of GaPO-34 are characterised by solid-state NMR, and their calcination investigated by TGA and in-situ powder XRD. An unusual dehydrofluorinated intermediate phase is isolated and characterised for the first time by solid-state NMR. The fully calcined material is shown to be stable under anhydrous conditions, but hydrates rapidly in air. The hydrated material is stable under ambient conditions, but collapses upon heating. Partial dehydration without collapse is achieved by gentle heating or room-temperature evacuation. The impurity phases, GaPO₄ berlinite and GaPO-X are investigated by solid-state NMR and, while the structure of GaPO-X remains unknown, much structural information is obtained.

The instrumental enrichment is a worldwide extended method of cognitive functions development, which has been used in the Czech Republic since 2000. Its author, Reuven Feuerstein, is strongly convinced that human being is able to modify oneself and to develop one's abilities. This method is based on elaborated theoretical concepts - especially on the theory of structural cognitive modifiability and mediated learning. This Diploma Thesis brings essentials information about the concepts related to the cognitive modifiability and considers tools of its application. In the qualitative study, we focus on Feuerstein's Instrumental Enrichment. In the course of ten moths we observed six clients of the DYS-Centrum Praha we attempted to map changes (or their manifestations) which might have appeared during the intervention. We acquired data by the process of observation (participative observation and video-analysis) and via semistructured interviews. We were interested in changes of cognitive functions manifestations, quality of language, quality of autonomous work and ability to process with the information efficiently. We registered changes in each of these areas. Some of them, were notable only during the FIE lessons, others also displayed at home or at school environment. Key words: cognitive...

Aim: The increasing importance of employee retention and talent acquisition have necessitated the need for a deeper understanding of employee psychology influencing these factors. As such, the current study examines the relationship between individual organizational attachment and work-nonwork conflict and work-nonwork enrichment.  Further interest was paid to possible moderating influences of work centrality, gender, number of dependents and number of contract hours. Design: Data was collected through online surveys. Participants were contacted through internet portals and selected business contacts at private companies. The study followed a cross-sectional design. The contributing sample consisted of 94 participants. Results: Organizational attachment styles contribute to differences in experienced work-nonwork conflict and work-nonwork enrichment. Anxious and avoidant organizational attachment exhibit a positive relationship with work-nonwork conflict and a negative relationship with work-nonwork enrichment. The relationship between organizational attachment anxiety and work-nonwork conflict is partially moderated by gender. No empirical support was found for the moderating influences of work centrality, number of dependents and number of contract hours. Implications: The results indicate that patterns of organizational attachment shape adult lives inside and outside of the workplace. Knowledge of how individuals experience work and nonwork depending on their organizational attachment allows for a sensitization towards individuality in the workplace. Catering to employees’ attachment needs could feasibly contribute to organizational viability and success. Novelty: Previous research has mostly examined attachment at work in terms of interpersonal attachment, while disregarding the role the organization can play as an attachment figure. While existing studies have examined the connection between (romantic) attachment and work-family or work-life conflict and enrichment, this study offers insights into how employees’ attachment relationships to the organization connects to the experience of work-nonwork conflict and enrichment.

O enriquecimento ambiental ou comportamental melhora a qualidade do cuidado ao animal cativo identificando e fornecendo os estímulos necessários para o seu bem-estar psicológico e fisiológico. O objetivo deste trabalho foi avaliar a possível influência das técnicas de enriquecimento ambiental nos parâmetros endócrinos e comportamentais de primatas da família Callitrichidae, sagüi-de-tufo-preto (Callithrix penicillata), mantidos em estabilidade social e isolados. Os animais tiveram seus comportamentos registrados pelo método de amostragem focal por intervalo de tempo totalizando 120 horas. A avaliação endócrina foi feita por métodos não invasivos, através da mensuração de metabólitos de cortisol urinário, pela técnica de radioimunoensaio. Os resultados apontaram diferenças estatísticas significativas nas variáveis comportamentais e do cortisol entre os indivíduos nas diferentes etapas do trabalho. Estes resultados mostraram que as técnicas de enriquecimento ambiental são eficientes para a diminuição dos desvios comportamentais e aumento da qualidade de vida dos animais em ambientes cativos. / Environmental or behavioral enrichment enhances the quality of captive animals` housing, as we identify and provide necessary stimuli to its psychological and physiological welfare. The goal of this review was to evaluate the possible influence of environmental enrichment techniques on endocrinal and behavioral parameters of primates from Callitrichidae family, black tufted-ear marmoset (Callithrix penicillata), kept in social stability and isolated. The animals had their behaviors registrated by the focal-interval sampling method, totalizing 120 hours. The endocrinal evaluation was made with non-invasive methods, through the measuring of urinary cortisol metabolites, using the radioimmuneassay thechnique. The results point out statistical differences in behavioral and cortisol variables among individuals in different stages of this work, and confirm that environmental enrichment techniques are efficient in decreasing abnormal behaviors and improving welfare of captive animals.

A Baía de Guanabara é um dos ecossistemas costeiros mais impactados do mundo. Apesar da fauna sublitoral de substratos inconsolidados ser amplamente utilizada como ferramenta ao monitoramento dos impactos de efluentes urbanos, pouco se sabe sobre a biologia das espécies dominantes. Foram analisadas amostras de variáveis ambientais e biológicas da coluna d\'água e do sedimento através de coletas mensais ao longo de um ano em uma estação fixa na Baía de Guanabara (ca. 12 m de profundidade), com objetivo de compreender a estratégia reprodutiva e a dinâmica populacional da espécie Poecilochaetus australis (Annelida: Polychaeta) em local sujeito à influência de efluentes urbanos não-tratados. Os resultados das variáveis ambientais demonstraram pequena flutuação. O sedimento foi composto essencialmente por frações finas de silte e argila com grãos pobremente selecionados, altas concentrações de matéria orgânica total, clorofila-a sedimentar e intensa atividade microbiana na camada superficial. A comunidade foi composta essencialmente por organismos tubícolas e sofreu pouca variação estrutural ao longo do tempo, sendo dominada pelos poliquetas P. australis, Spiochaetopterus nonatoi, Aricidea suecica simplex, Prionospio steenstrupii, pelos anfípodes Tiburonella viscana e uma espécie não identificada da família Corophiidae, uma espécie de isópode da família Anthuridae, o braquiúro Pinnixa sp. e o cladócero Daphnia sp. Não foram verificadas diferenças temporais significativas entre as riquezas e as diversidades específicas. Os valores médios de riqueza e a diversidade específica ficaram entre 15 táxons e 2,77 bits por indivíduo, respectivamente. Houve investimento reprodutivo contínuo das fêmeas de P. australis. A menor fêmea madura (0,8 mm; largura do 7° setígero - D7) foi encontrada em junho de 2005. Grande parte dos indivíduos maduros concentrou-se entre 1,1 e 1,3 mm D7. Os maiores ovócitos foram encontrados no mês de dezembro de 2005 com 163 ?m de diâmetro, e os menores em março de 2006 com 115 ?m. Foram observadas diferenças significativas no grau de desenvolvimento dos ovócitos ao longo do ano com amadurecimento dos ovócitos de um mês para o seguinte. Os ovócitos tenderam a atingir seu ápice de desenvolvimento em dezembro de 2005. Não foi possível determinar sincronismo entre as fêmeas maduras. Não houve variabilidade mensal significativa da abundância de P. australis. O tamanho médio dos 1575 indivíduos amostrados de P. australis ficou em 0,71 mm D7 (dp = 0,36). Foram identificadas oito classes de tamanho. O maior indivíduo foi uma fêmea com 1.5 mm D7 e os menores foram encontrados entre as larvas planctônicas com 0,15 mm D7 e nos recrutas do sedimento com 0,20 mm D7. Em todos os meses, as classes de tamanho inferiores (0,20 - 0,55 mm) estiveram presentes, sendo responsáveis por grande parte da densidade encontrada. O tamanho assintótico de P. australis ficou em 0,97 mm D7, sendo que 79,1% dos indivíduos encontraram-se neste ou abaixo deste tamanho. A constante de crescimento K ficou em 1,7. A taxa de mortalidade ficou em 3,12. Em grande parte do período estudado houve contribuição expressiva de recrutas na abundância de indivíduos, sem que as classes de tamanho maiores fossem excluídas. A população manteve-se estável, já que foi capaz de manter simultaneamente adultos com potencial reprodutivo e alta disponibilidade de larvas e recrutas em ambiente propício ao desenvolvimento, crescimento e reprodução. Não foi encontrado nenhum resultado que apontasse ciclo de vida do tipo oportunista. / Guanabara Bay is one of the most human impacted coastal ecosystems in the world. Despite the wide use of sublittoral soft bottom fauna on urban sewage monitoring programs, little is known about the biology of dominant species. Water column and sediment environmental and biological variables were monthly analyzed in a permanent station in Guanabara Bay (ca. 12 m depth) in order to understand the reproductive ecology and population dynamics of Poecilochaetus australis (Annelida: Polychaeta) in a grossly sewage impacted area. Environmental variables showed only minor fluctuations. Surface sediments were composed of poorly sorted silt and clay fractions, with high concentrations of total organic matter, chlorophyll-a and microbial biomass. The softbottom community structure showed only small, non-significant temporal variations with a large abundance of tube dwellers. Macroinfauna was dominated by the polychaetes P. australis, Spiochaetopterus nonatoi, Aricidea suecica simplex and Prionospio steenstrupii; the amphipods Tiburonella viscana and a non-identified species of the family Corophiidae; a species of the isopod family Anthuridae; the brachiuran Pinnixa sp.; and the cladoceran Daphnia sp. There were no significant temporal differences in species richness and diversity. Mean values for these two parameters were 15 taxa and 2.77 bits ind.-1, respectively. Reproductive output was continuous in P. australis females. The smallest ripe female (0.8 mm; 7th setiger width - D7) was found in June 2005. Most mature individuals measured between 1,1 and 1,3 mm D7. The largest oocytes were found in December 2005 measuring 163 ?m in diameter. The smallest ones were 115 ?m and occurred in March 2006. Significant temporal differences were found in oocyte development with fully matured oocytes occurring every month. However, most oocytes were mature in December 2005. Analysis of ripe females did not show synchronous development. There were no significant differences in numerical abundance of P. australis. Mean D7 size was 0.71 mm (SD=0,36; N=1575). Eight size classes were identified, with the largest individual a female 1.5 mm D7. The smallest individuals were a planktonic larva 0.15 mm D7 and a recently settle recruit 0.20 mm D7. The smallest size classes (0.20 - 0.55 mm D7) were present throughout the sampling period, responding for most of the individuals collected. P. australis asymptotic size was 0.97 mm D7, with over 79% being smaller or at this size. The growth constant K was 1.7 and the mortality rate 3.12. There was a large contribution of newly settled recruits on all studied months. The population was stable, showing the presence of mature adults and a high availability of larvae and recruits. There was no evidence of an opportunist type life cycle for P. australis.

A remoção de compostos sulfurosos (sulfeto/sulfato) de águas residuárias tem grande importância para a saúde humana e para o ambiente. A biorremediação desses compostos, através da utilização de bactérias fototróficas anoxigênicas apresenta-se como alternativa viável ecológica e economicamente. Neste projeto de pesquisa realizaram-se ensaios em reatores em batelada expostos à iluminação fluorescente, com a finalidade de avaliar a utilização de sulfeto por cultura enriquecida de sulfubactérias fototróficas verdes, proveniente de sedimento de lagoa de estabilização. A avaliação da utilização de sulfeto e os resultados da cinética de crescimento da cultura visam a possibilidade de aplicação das bactérias fototróficas anoxigênicas no tratamento de águas residuárias. Na avaliação cinética de crescimento da cultura enriquecida de sulfubactérias fototróficas verdes foi verificado diminuição na velocidade de crescimento de 0,0346 h-1 para 0,0035 h-1 com o aumento da concentração inicial de sulfeto de 11,4 para 529,6 mg-S/L, respectivamente. O tempo de geração apresentou comportamento crescente com valores iguais a 19,98 h e 119,18 h, respectivamente. Os valores do coeficiente de conversão de sulfeto relativo ao crescimento de microrganismos (Yx/s), apresentaram diminuição progressiva com o aumento da concentração inicial de sulfeto, sendo esta queda mais acentuada no intervalo de concentrações de 40,5 a 147,2 mg-S/L. / The removal of sulphur compounds (sulfide/sulfate) from wastewaters is very important for human and for the environmental. The bioremediation of these compounds, applying anoxigenic phototrophic bacteria has been presented as a possible alternative. The aim of this work is to evaluate the utilization of sulfide by the enrichment of green sulphur bacteria proceeding from stabilization pond sediment, through the realization of batch reactors assays, which are exposed to fluorescent ilumination. The determination of the sulfide utilization and the results of the kinetic growth were done to clarify the possibility of the application of anoxigenic phototrophic bacteria in the wasterwater systems. In kinetic experiments it was observed that the specific rate of bacterial growth changed from 0.0346 h-1 to 0.0035 h-1. Then the initial sulfide concentration was increased form 11.4 mg-S/L to 529.6 mg-L. The doubling time showed an increase from 19.98 h to 119.18 h. The sulfide conversion to microorganism biomass (Yx/s) progressively decrease with the increase of sulfide concentration. Such a decrease was higher in between sulfide concentrations of 40.5 mg-S/L to 147.2 mg-S/L.