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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Reologia e microestrutura de geis acidos de gelana / Rheology and microstructure of gellan acid gels

Yamamoto, Fabiola 21 February 2006 (has links)
Orientador: Rosiane Lopes Cunha da / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-05T15:56:41Z (GMT). No. of bitstreams: 1 Yamamoto_Fabiola_M.pdf: 2839166 bytes, checksum: aa7b4ca2a9be01725a763b4a3e96738b (MD5) Previous issue date: 2006 / Resumo: A influência da concentração de polissacarídeo, do pH de equilíbrio (de 2,0 a 4,0) e da aplicação de tratamento térmico (70 ou 90ºC/ 30min) sobre as propriedades reológicas e de microestrutura de géis de gelana acidificados lentamente pela adição de glucona-d-lactona (GDL) foi estudada nesse trabalho. Os sistemas foram caracterizados quanto à cinética de gelificação e propriedades dos géis formados, como as reológicas em compressão uni- e biaxial, capacidade de retenção de água (WHC), microestrutura e turbidez. Em todas as amostras que formaram géis auto-sustentáveis, com exceção daquelas com 1% de gelana nos menores pHs, foi possível determinar o ponto de gel a partir de ensaios oscilatórios, sendo que o tempo do mesmo diminuiu com o aumento da concentração de polímero, com o tratamento térmico, e com a diminuição do pH final. Todos os géis auto-sustentáveis foram transparentes e não apresentaram sinerese. A tensão de ruptura aumentou com a diminuição do pH, aumento da concentração de gelana e submissão a tratamento térmico antes da adição de GDL, porém diminuiu quando este foi realizado depois da acidificação. A WHC tornou-se maior com o aumento da concentração de gelana e do pH nos sistemas de concentração 1% e 0,5%, no entanto, a 0,2%, ela aumentou com a diminuição do pH. A microestrutura dos géis mostrou correlação direta com as propriedades reológicas em compressão. A análise da dimensão fractal dos géis só foi possível em pHs 2,5 e 2,0, e os sistemas apresentaram estrutura fractal com regime de ligação fraca. Todas as amostras mostraram comportamento de fluido lei da potência em escoamento extensional. A correlação entre turbidez e força dos géis foi linear. No entanto, a turbidez mostrou-se mais sensível às mudanças estruturais do que as propriedades mecânicas / Abstract: The influence of polysaccharide concentration, pH at equilibrium (2,0 - 4,0) and annealing (70 or 90ºC/30min) on rheological properties and microstructure of gellan gels formed by acidification of glucon-d-lacton GDL was evaluated in this study. Gels were characterized in relation to their gelling kinetics, mechanical properties at fracture, water holding capacity (WHC), microstructure, turbidity and rheological parameters in extension. In all samples, with exception to that of 1% concentration formed at pHs 2,5 and 2,0, it was possible to determine the gel point by oscilatory measurements. The time at which gel point occurred diminished by raising polymer concentration, annealing and lowering final pH. All gels were transparent and exhibited no sign of syneresis. Failure stress increased at lower pH values, higher concentrations and gels were even stronger when made from annealed solution. When gels were annealed after pH reached equilibrium, their failure stress decreased. The WHC for 1% and 0,5% gels was higher at enhanced concentrations and higher pH values and for 0,2% gels, it was higher at lower pH values. Microstructure of gels showed straight correlation with their rheological properties in compression. Analysis of fractal dimension of the gels was only possible at pHs 2,5 and 2,0. In this case, the systems showed fractal structure in the weak¿link regime. All samples showed power law behaviour in extension. The turbidity and the force of gels showed linear correlation. Nevertheless turbidity measurements were more sensitive to structural changes than were mechanical properties / Mestrado / Mestre em Engenharia de Alimentos
182

Desenvolvimento de fatores de normalização de impactos ambientais regionais para avaliação do ciclo de vida de produtos no Estado de São Paulo / Development of normalization factors to life cycle assessment in São Paulo state

André Luiz Ribeiro Tachard da Silva 30 April 2010 (has links)
A normalização é uma importante etapa da Avaliação do Ciclo de Vida, uma vez que fornece uma unidade comum, permitindo a comparação das diferentes categorias de impacto. A referência de normalização mais utilizada considera o impacto das atividades totais da sociedade num certo período de tempo. Estes dados são inexistentes no Brasil para impactos regionais e locais, de forma que este trabalho objetivou iniciar o preenchimento dessa lacuna, com os fatores de normalização para as categorias \"acidificação\" e \"eutrofização\", no estado de São Paulo. Tais fatores foram calculados com base em um inventário das estimativas anuais de aporte ao meio ambiente de substâncias contribuintes para estas categorias, cuja realização possibilitou a análise do estado da arte desses impactos em São Paulo e dos setores responsáveis pela geração das substâncias contribuintes. Conforme esperado, os fatores (ou referências) de normalização encontrados foram diferentes daqueles por hora utilizados no Brasil, baseados em dados europeus. Entre as razões que explicam esta diferença estão a baixa emissão de \'SO IND.X\' devido a matriz energética brasileira, o uso de etanol com combustível e o despejo de esgoto sem tratamento (ou tratamento inadequado). / Normalization is an important step in Life Cycle Assessment as it provides a common unit, allowing the comparison of the different impact categories. The normalization reference most widely used considers the \"background\" impact from the total activities of society in a chosen reference period. These data are inexistent in Brazil for regional and local impacts so that this work aimed to begin filling this lack, first developing normalization factors for the categories \"acidification\" and \"eutrophication\" in the state of Sao Paulo. These factors were calculated from an inventory of the annual load to the environment of substances contributing to these categories; the production of this inventory allowed the analysis of a) the state of the art of these impacts in Sao Paulo and b) the sectors responsible for the generation of contributors. As expected, normalization factors (or references) were different from those currently used in Brazil, based on European data. Among the reasons for this difference are lower \'SO IND.X\' emissions due to the Brazilian energy matrix, the use of ethanol as fuel and disposal of sewage without treatment (or mistreatment).
183

Efeitos das mudanças climáticas na regulação de biomarcadores em Echinaster brasiliensis (Echinodermata: Asteroidea) / Effects of climate changes on biomarkers regulation in Echinaster brasiliensis (Echinodermata: Asteroidea)

Patrícia Lacouth da Silva 10 December 2015 (has links)
Diante do quadro atual de previsões de mudanças climáticas, estudos a respeito das possíveis respostas dos organismos a estas alterações são importantes. Com a finalidade de prever e verificar se estas serão de fato deletérias ou se os organismos são capazes de lidar com elas sem alterações na sua fisiologia, e consequentemente na estrutura do ambiente, E. brasiliensis foi utilizada como modelo para estudar possíveis impactos do aumento da temperatura e acidificação dos oceanos na sua fisiologia. Para isso, espécimes foram expostos a 9 possíveis combinações de temperatura (24ºC, 28ºC e 30ºC) e pH (8.0, 7.7 e 7.3) em diferentes intervalos de tempo (1, 3, 12, 24 e 48 h). Amostras de gônadas e fluido celomático foram coletadas para avaliar a expressão das proteínas de estresse HSP70, AIF-1 e p38-MAPK, e a variação no número e viabilidade dos celomócitos. Nossos resultados mostram que o modelo é sensibilizado pelas mudanças no ambiente, através da hiper-regulação das proteínas de estresse. O cenário considerado mais extremo (30°C + pH7.3) ocasionou a morte de 100% dos organismos após 24horas. E o segundo cenário mais severo (30°C + pH7.7) desencadeou o desenvolvimento de ulceração de pele. Os efeitos são mais pronunciados nos celomócitos e a acidificação da água parece ter efeitos antagônicos com a temperatura nos celomócitos e sinérgicos nas gônadas. Embora a resposta tenha sido sistêmica, o grau e a dinâmica foram distintos em relação às diferentes amostras e estresses. Podendo causar modificações na resposta imune dos organismos e consequentemente na sobrevivência da espécie a longo prazo. / Under the current Climate Change context, studies about the potential responses of the organisms to their changing environment are of extreme importance. Recent studies point out the synergy of temperature and ocean acidification altogether. In this study, we used the sea star E. brasiliensis to assess the physiological effects of rising temperature, seawater acidification and the interaction of both factors. Independent individuals (N=225) were exposed to 9 possible combinations of temperature (24ºC, 28ºC and 30ºC) and pH (8.0, 7.7 and 7.3), for 1, 3, 12, 24 and 48 h. We compared the stress produced by these treatments measuring the expression of heat shock proteins (HSP70), the production of the allograft inflammatory factor (AIF−1) and the activation of mitogen kinases (MAPKs) at both gonad and celomic fluid. Furthermore, we assessed the quantity and quality of coelomocytes. Our results demonstrated that E. brasiliensis is vulnerable to the interaction of temperature and acidification. All the stress proteins evaluated were upregulated. The extreme scenario (30°C + pH7.3) caused the death of 100% of organisms after 24 hours, while the second most severe scenario (30°C + pH7.7) triggered skin ulceration. Nevertheless, we found that water acidification produces antagonistic effects to the temperature in coelomocytes and synergistic effects in gonad cells. Furthermore, these effects were more pronounced in the coelomocytes than in the gonads. The systemic response found in this study suggest that the interactive effects of elevated temperatures in conjunction with ocean acidification may endanger the survival of this species, and it could compromise the ecosystem functioning at long term.
184

Efeitos de dosegens extremas de cloro e pH na vazão de gotejadores autocompensantes (irrigação localizada) / Chlorine and pH extreme dosages effects on the flow rate of self compensating emitters (drip irrigation)

Marconi Batista Teixeira 15 December 2006 (has links)
Este projeto de pesquisa foi desenvolvido visando quantificar possíveis distúrbios de vazão em emissores do tipo gotejador (irrigação localizada) submetidos à aplicação de cloro livre e acidificação em condições estática e dinâmica de fluxo de água no sistema. O experimento foi realizado no período de setembro de 2005 a junho de 2006, utilizando-se 14 modelos de gotejadores autocompensantes com suas respectivas linhas gotejadoras montadas em uma bancada de ensaios em estrutura metálica. Os tratamentos utilizados no experimento foram: a) aplicação dinâmica de 100 mg L-1 de cloro livre com pH na faixa de 5,5 a 6,0; b) aplicação estática de 100 mg L-1 de cloro livre com pH na faixa de 5,5 a 6,0; c) aplicação de ácido nítrico com pH na faixa de 2,0 a 3,0 durante ½ h (sistema pressurizado); d) aplicação de ácido nítrico com pH na faixa de 2,0 a 3,0 durante 12 h (sistema pressurizado). Foram realizadas curvas vazão versus pressão para cada tratamento em três diferentes temperaturas da água (15, 25 e 40° C). O delineamento experimental utilizado foi o inteiramente aleatorizado em esquema fatorial, com utilização dos testes ?F? para análise de variância e Tuckey, a 5% de significância, para comparação de médias e análise de regressão. Os resultados obtidos mostram que para o tratamento da água com 100 mg L-1 de cloro livre em condição dinâmica, ocorreu um decréscimo de 10 a 20% em média da vazão (L h-1) para alguns modelos de gotejadores mais sensíveis aos produtos químicos, sendo que o modelo I apresentou redução drástica de vazão na ordem de 100% em virtude do bloqueio total do labirinto do emissor, em decorrência do aumento de 112% do volume da membrana após 2688 h de aplicação contínua de cloro. Os tratamentos estáticos não apresentaram variações acentuadas de vazão média (L h-1), coeficiente de variação (%), uniformidade de distribuição (%), Vazão Relativa (%) e Grau de Entupimento (%). Verificou-se relação linear entre a vazão e a temperatura da água para os gotejadores novos, sendo que após a aplicação dos diferentes tratamentos, as curvas vazão versus pressão para cada modelo de gotejador sofreram influência tanto da pressão quanto da temperatura de maneira distinta. / This research project was developed to quantify possible flow rate variation in emitters (drip irrigation) submitted to the application of free chlorine and acidification under static and dynamics conditions of water flow. The experiment was accomplished in the period of September, 2005 to June, 2006, being analyzed 14 models of pressure compensating emitters set up in a metallic bench. The treatments used in the experiment were the following ones: a) dynamic application of 100 mg L-1 of free chlorine with pH 5,5 to 6,0; b) static application of 100 mg L-1 of free chlorine with pH 5,5 to 6,0; c) application of acid nitric with pH 2,0 to 3,0 during ½ h (pressurized system); d) application of acid nitric with pH 2,0 to 3,0 during 12 h (pressurized system). The operating pressures and emitter model combination were: 50, 100, 200, 300, 400 kPa for emitters A to N, in three different water temperatures (15, 25 and 40° C). The obtained values of flow rate were used to calculate the CUD, CV, relative flow rate, the percentage of drippers in each flow rate range, and the number of the drippers completely clogged. The statistical analysis of the treatments were accomplished by Tukey test at 5% probability. The obtained results show that for the treatment of the water with 100 mg L-1 of free chlorine in dynamic condition, a reduction from 10 to 20% of the flow rate (L h-1) occurred for some models more sensitive to chemical products. Model I presented drastic reduction of flow rate in the order of 100% by total blockade of the labyrinth of the emitter, due to the increase of 112% of the volume of the membrane after 2688 h of continuous application of 100 mg L-1 of chlorine free with pH 5,5 to 6,0. The static treatments didn\'t present accentuated variations of medium flow rate (L h-1), variation coefficient (%), distribution uniformity (%), relative flow rate (%) and degree of blockage (%). For pressure compensating emitters, where the discharge sensitivity to temperature is insignificant, after the application of the different treatments, the measured discharge/pressure relationship for each emitter model was sensitive to pressure as well to temperature.
185

Ein neuer Aspekt im Umweltwandel - Dynamisierung von Arsen in einem Speichersystem in der Folge rückläufiger Depositionslast

Weiske, Arndt 13 December 2017 (has links) (PDF)
Arsen im Trinkwasser und in der Nahrung stellen regional bedeutsame Probleme dar. Die Abschätzung der Dimension und eine wissenschaftliche Klärung der Ursachen sind Voraussetzung für den Schutz von Mensch und Natur. Mit dem Speicher Altenberg wurde ein Trinkwasserspeichersystem untersucht, in dem erhöhte Arsenkonzentrationen zu beobachten sind. Ziel der Untersuchungen waren Erkenntnisse über eine mögliche Fortsetzung des bisher beobachteten Trends zu steigenden Arsenkonzentrationen. Hierzu wurde das System in Kompartimente unterteilt und diese auf ablaufende Prozesse und Dynamiken untersucht. Das System besitzt eine geringe Produktivität auf Grund von Nährstoffarmut, insbesondere einer Phosphat-Oligotrophie. Es ist, wie viele Gewässer in der nördlichen Hemisphäre, im Kontext sinkender Immissionsbelastungen wie auch des Klimawandels von hohen und zunehmenden Huminstoffeinträgen aus dem Einzugsgebiet geprägt. Hinzu kommt das Wirken von internen und externen Arsenquellen. Am Grund der Gewässer wurden arsenreiche und humose Substrate nachgewiesen. Sie sind einerseits die Folge einer lang anhaltenden Akkumulation von Sedimenten, die auf Einträge aus dem von arsenreichen Grundgesteinen und anmoorigen Böden geprägten Einzugsgebiet zurückgehen. Andererseits kommt eine Überstauung anmooriger Böden und Moore mit gespeichertem lithogenen bzw. chalkogenen Arsen am Baugrund der Speichergewässer in Frage. Die Bedeutung deponierter Flugaschen wird für das System als untergeordnet eingeschätzt. Für den im System als Vorsperre genutzten Galgenteich zeigt sich seit Beginn der Arsenmessungen im Jahre 1997 ein bis zum Jahre 2000 andauernder stetiger Anstieg der Arsenkonzentration, der statistisch signifikant mit einem Rückgang der Nitratkonzentration einhergeht. Diese ist ihrerseits Teil eines allgemeinen Trends einer ökologischen Regeneration mitteleuropäischer bewaldeter Wassereinzugsgebiete seit Ende der Achtzigerjahre in der Folge abnehmender Depositionslasten. Die wahrscheinlichste kausale Verknüpfung zwischen beiden Parametern ist eine Änderung des redoxchemischen Milieus der Gewässersedimente. Zu Zeiten der hohen Depositionen unterdrückten hohe Konzentrationen von Nitrat als sekundärem Elektronenakzeptor eine Freisetzung von Arsen aus Eisenoxid-Sorbaten. Im Zuge andauernder reduktiver Prozesse und mit dem Rückgang der Nitratkonzentration gewinnen Rücklösungsprozesse an Bedeutung. Seit der Jahrtausendwende zeigen sich reguläre zyklische Jahresverläufe der Arsenkonzentration mit Maxima im Spätsommer und Minima im Frühjahr. Eine Bilanzierung der Massenströme legt eine Quellfunktion der Gewässersedimente im Sommerhalbjahr offen, während der Rückgang der Arsenkonzentration im Winterhalbjahr hauptsächlich auf eine Auswaschung und, zu geringerem Anteil, auf eine interne Senkenfunktion zurückgeführt werden kann. Der Speicher Altenberg ist im Sommer thermisch geschichtet. Aber eine Schichtung von Arsen ist weit schwächer ausgeprägt. Ein Anstieg der Arsenkonzentration wurde sowohl im Hypo- als auch im Epilimnion nachgewiesen. Dies legt eine Arsenfreisetzung auch aus epilimnischen Sedimenten nahe, trotz oxischer Bedingungen im überstehenden Wasserkörper. Der dystrophen Natur des Gewässers entsprechend, wird die Triebkraft der zur Arsenfreisetzung führenden respirativen Prozesse dem Abbau humosen Kohlenstoffes zugeordnet. Für Sicker- und Interstitialwässer im System wurde die Mobilisation des Arsens in Zusammenhang mit der Respiration huminstoff-bürtigen Kohlenstoffes nachgewiesen. Neben der internen Arsenmobilisation ist auch die Arsennachlieferung aus dem Einzugsgebiet von Bedeutung. Die Arsenfracht befindet sich in diesen Wasserströmen vorzugsweise in Abhängigkeit von gelöstem organischen Kohlenstoff und der Abflussintensität. Daraus ergibt sich für den Arsenhaushalt des Speichersystems eine besondere Bedeutung von Starkregenereignissen mit verstärktem hypodermischen Abfluss und der Verfrachtung von Arsen in Assoziation mit wasserlöslichen Huminstoffen. Es wird eine Fallunterscheidung vorgestellt, wonach a) in trockenen Jahren mit geringen Durchflüssen sich Arsen aus der internen Rücklösung aus Sedimenten im Wasserkörper des Speichers anreichert; b) bei durchschnittlichen Durchflüssen im Speicher Verdünnungseffekte über die Anreicherung dominieren und tendenziell niedrige Arsenkonzentrationen resultieren; sowie c) in Jahren mit hohen dynamischen Durchflüssen bzw. ausgeprägten Starkregenereignissen ein verstärkter Eintrag aus dem Einzugsgebiet die Arsenkonzentrationen im Speicher ebenfalls ansteigen lässt. Eine exemplarische Analyse der chemischen Spezies des Elements hat ergeben, dass anorganisches fünfwertiges Arsen die dominante Form im Wasser des Speichers Altenberg ist. Der Anteil von höher toxischem dreiwertigen Arsen ist niedrig, ebenso auch der von methylierten Spezies. Daher wird auch eine Bildung volatiler Methylspezies, d.h. eine Öffnung des Arsenhaushaltes zur Atmosphäre, als unbedeutend eingeschätzt. Im Speichersystem offenbart sich eine spezifische Verknüpfung eines an Eisen-Huminstoff-Kolloide gebundenen Antransportes von Arsen aus dem Einzugsgebiet mit einer auf Huminstoffabbau basierenden, redoxchemisch gesteuerten saisonalen Arsenfreisetzung aus den Sedimenten. Dies hat Modellcharakter für Gewässersysteme, in denen hohe Huminstoffmobilität mit geogen oder auch anthropogen bedingten Arsenvorräten zusammentrifft. / Arsenic in drinking water and food represent regionally significant problems. The estimation of the dimension and a scientific explanation of the causes is a prerequisite for the protection of humans and nature. The Altenberg reservoir system was investigated as a drinking water facility, where elevated arsenic concentrations are observed. The aim of the investigations was to get findings about a possible continuation of recently observed trends of increasing arsenic concentrations in the water reservoir. For this purpose, the system was divided into compartments and these were investigated for running processes and dynamics. The system has a low productivity due to a low nutrient state, in particular a phosphate oligotrophy. Like a lot of surface waters in the northern hemisphere, it is shaped by high and increasing inputs of humic matter from the catchment area in context of declining immissions as well as of climate change. Additionally, there are internal and external sources of arsenic. At the bottom of the reservoirs, sediments rich in arsenic and humic matter were found. On the one hand side, they are the result of a long-lasting accumulation of sediments which originate in inputs from the catchment area, which is shaped by arsenic-rich basic rocks and histic soils. Likewise, an inundation of gleyic and histic soils with stored lithogenic respectively chalcogenic arsenic inside the construction ground of the reservoirs is an option. The importance of deposited fly ash for the system is assessed to be subordinate. For the Galgenteich, which is operated as a predam, since the beginning of arsenic measurements in 1997 an until the 2000 lasting steady increase in the concentration of arsenic concentration was found, which is significantly associated with a decrease in nitrate concentration. The nitrate concentration decrease in turn is part of an ecological regeneration of Central European forested catchments since the late eighties as a result of decreasing deposition loads. The most likely causal linkage between both parameters is a change in the redox-chemical environment of reservoir sediments. At past times of high depositions, high concentrations of nitrat as a secondary electron acceptor suppressed a release of arsenic from iron oxide sorbates. In the course of reductive processes, and with the decrease in nitrate concentration, release processes gain importance. Since the turn of the millennium regular cyclic annual courses of the arsenic concentration emerge with maxima in the late summer and minima in spring. An accounting of the mass flows reveals a source function of reservoir sediments in the summer season, whilst the decrease of the arsenic concentration during the winter months can be mainly attributed to washout and to a lesser proportion to an internal sink function. The Altenberg reservoir is thermally stratified in summer. But a stratification of arsenic is far less pronounced. An increase in the arsenic concentration was detected in hypolimnion and in epilimnion too. This suggests an arsenic release also from epilimnetic sediments despite oxic conditions in the overlaying water body. According to the dystrophic nature of the water body, the driving force leading to arsenic release during the respiratory processes is assigned to the use of humic carbon. For seepage and interstitial waters in the system, the mobilization of arsenic has been demonstrated in connection with the respiration of humic carbon. In addition to the internal arsenic mobilization, also a recent arsenic delivery from the catchment area is of importance. The arsenic load in these water flows preferably depends on contents of dissolved organic carbon and on runoff intensity. That implies a special meaning of heavy rainfall events with intensified hypodermic runoff and the transportation of arsenic in association with water-soluble humic matter for the arsenic budget of the reservoir system. A case distinction is presented, according to which a) in dry years with low flow rates sediment released arsenic accumulates in the reservoir water to higher concentrations; b) at average flow rates in dilution effects dominate over the enrichment with the result of low arsenic concentrations; and c) in years with high dynamic flows and strong heavy rains an increased input from the catchment area can also increase the arsenic concentration in the reservoir. An exemplary analysis of chemical species has shown that inorganic pentavalent arsenic is dominant in the water of the Altenberg reservoir. Higher toxic trivalent arsenic was found to a lesser extent as well as methylated species. Therefore, a formation volatile methyl species, i.e. an opening of the arsenic budget to atmosphere, is assessed to be insignificant. The dynamics in the reservoir system reveal a specific linkage between a catchment arsenic feed based on arsenic in iron-humic colloids and a redox-chemically controlled arsenic release from the sediments of the reservoir. This serves as a model for water systems, where high humic matter mobility coincides with geogenic or anthropogenic arsenic inventories.
186

Improving our understanding of evolutionary persistence in an increasingly high CO2 world : insight from marine polychaetes at a low pH vent system

Lucey, Noelle Marie January 2016 (has links)
The main aim of this thesis was to determine how marine metazoans might persist as ocean acidification (OA) conditions intensify. This was done using a combination of field surveys, field transplants and laboratory experiments with polychaetes from a site where volcanically-derived CO2 gas bubbles through the seafloor and drives the seawater pH down, resulting in a marine ecosystem representative of global OA projections for, or before, the year 2100. My first objective was to identify phenotypes, or traits, associated with OA tolerance (Chapter 2 and 5). To do this, I characterized the distribution of dominant calcifying polychaetes along natural pH gradients and used a comparative species recruitment trial to investigate life history traits underlying species’ OA tolerance, or vulnerability. I first found two dominant, closely related species of polychaete: Pileolaria militaris Claparède, 1870 and Simplaria sp. (Serpulidae, Spirorbinae). I then found that increased fecundity and rapid settlement are important traits in determining species’ abilities to persist in low pH environments (Chapter 2). Afterwhich, I investigated the life history traits of the non-calcifying polychaete, Platynereis dumerilii (Audouin & Milne Edwards, 1834), of one of the few species from the low pH site known to have broadcasting, pelagic development. I performed breeding experiments on P. dumerilii collected in both ambient and low pH sites and found that specimens from the low pH site were actually the direct developing brooder sister species, Platynereis massiliensis (Moquin-Tandon, 1869). By reanalayzing the distributions of both species at each site using genetic barcoding, I found clear evidence that direct development and brooding are dominant traits at low pH site, and for OA persistence (Chapter 5). My second objective was to use reciprocal transplant experiments to compare the relative importance of local adaptation and/or plasticity as potential mechanisms responsible for the differential tolerances of populations of the polychaete species Simplaria sp. to low pH. Laboratory transplants indicate that a local adaptation response occurred through genetic accommodation in the Simplaria sp. population from the low pH site. However, neither local adaptation nor plasticity appeared responsible for this species natural low pH persistence when assessed in situ (Chapter 3 & 4). My final objective was to create a framework using the polychaete vent model to identify other types of marine metazoans that are likely to be able to adapt to, and survive, under the predicted environmental conditions (Chapter 5). I overviewed the life history strategies of all dominant polychaetes in the low pH sites, and related trends in their life history strategies to those of other marine invertebrates. Brooding and direct development appear to be key traits for species likely to persist in future oceans pH. I conclude by summarizing how research regarding evolutionary responses may be advanced to add confidence to our projections of future marine metazoan responses.
187

Effects of Ocean Warming and Acidification on Fertilization Success and Early Larval Development in the Green Sea Urchin, Lytechinus variegatus

Lenz, Brittney L 01 December 2017 (has links)
Climate change is predicted to affect the larval stages of many marine organisms. Ocean warming can reduce larval survival and hasten larval development, whereas ocean acidification can delay larval development. Ocean acidification is especially concerning for marine organisms that develop and grow calcified shells or skeletons in an environment undersaturated with calcium carbonate minerals. This study assessed the effects of ocean warming and acidification on the fertilization and larval development of the green sea urchin, Lytechinus variegatus, a tropical species common in Florida and the Caribbean. After spawning, gametes were fertilized and embryos/larvae were reared at: 1) 28°C and pH 8.1 (control), 2) 28°C and pH 7.8 (ocean acidification scenario), 3) 31°C and pH 8.1 (ocean warming scenario), and 4) 31°C and pH 7.8 (ocean warming and acidification scenario). Exposure to acidified conditions had no effect on fertilization, but delayed larval development, stunted growth and increased asymmetry. Exposure to warm conditions decreased fertilization success at a high sperm to egg ratio (1,847:1), accelerated larval development, but had no significant effect on growth. Under exposure to both stressors (ocean warming and acidification), larval development was accelerated, but larvae were smaller and more asymmetric. These results indicate that climate change will have a serious impact on the larval development and growth of the green sea urchin, L. variegatus, and may negatively affect its persistence.
188

Combined effects of ocean acidification, ocean warming and oil spill on aspects of development of marine invertebrates

Arnberg, Maj January 2016 (has links)
For decades, humans have impacted marine ecosystems in a variety of ways including contamination by pollution, fishing, and physical destruction of habitats. Global change has, and will, lead to alterations in in a number of abiotic factors of our ocean in particular reduced oxygen saturation, salinity changes, elevated temperature (ocean warming or OW) and elevated carbon dioxide (ocean acidification or OA). Now and in the future, OA and OW will operate together with local anthropogenic drivers such as oil pollution. And yet, at present, very little is known about their potential combined interactive effects on physiological performance and tolerance of marine organisms. Therefore, multiple driver experiments are required if we are to understand and predict future vulnerability of species, populations and ecosystems. Early life stages of invertebrates are generally considered most vulnerable to environmental stress. However, few studies consider the combined effects OA and OW on survival and growth during early development of marine invertebrates, and to our knowledge, there is no information on the additional effects of oil pollution. Therefore, the aim of this thesis was to investigate the effects of combined exposure to OA, OW, and incorporating local drivers such as oil pollution on the development, morphology and physiology of three economically and ecologically important marine invertebrates. These are Northern shrimp Pandalus borealis, Northern krill Meganyctiphanes norvegica, and the green sea urchin Strongylocentrotus droebachiensis. All are cold-water species, assumed to have a narrower tolerance than more temperate species, and so could be particular sensitive to combined stressor affects. Both Northern krill and to a lesser extent Northern shrimp larvae survived experimental conditions, mirroring those predicted under a future global change scenario (combined OA and OW exposure). Neither was hatching success affected. Both shrimp and krill larvae exhibited accelerated developmental rates and incurred greater maintenance costs as a result of exposure to these stressors. Shrimp larvae showed accelerated developmental rates (-9 days), increased metabolic rates (+20 %), and increased feeding rates (+20 %), but reduced growth (- 9 %) when exposed to OW compared with the control. OA increased development rate but only at the control temperature. Although juvenile mortality of krill was not affected by predicted OA/OW conditions, metabolic rate increased significantly (+ 36 %), as did larval developmental rate, while number of moults, feeding rate and growth (- 67 %) decreased significantly (- 67 %, - 60 % and -8 % respectively). Accelerated development was accompanied by greater maintenance costs possibly due to experience a mismatch between energy supply and demand. Both species had an excess of food, and so growth reduction was more likely to be associated with higher metabolic demands in the future global change treatments. Food shortage in situ, due to variable food availability in the sea and/or mismatch with key prey species (algae and zooplankton) could result in more negative effects on growth and ultimately survival. Green sea urchins were also able to survive OA exposure, without detectable effects on hatching success. However, at day 44 post-fertilization, larval body length in the OA treatment was 9 % lower compared to the control. Furthermore, there was a significant tendency of urchin larvae to increase swimming activity in the OA conditions that might indicate compensatory feeding. Elevated maintenance and repair costs as a result of exposure to multi-stressors affected the energy budget of all the three species studied here resulting in reduced growth. Global drivers (OA and OW) resulted in trade-offs with more energy reallocated to swimming activity and metabolism, rather than growth. Exposure to oil reduced the acquisition of energy by reduced feeding which in turn resulted in less energy being available for growth. Both shrimp and sea urchin larvae showed reduced activity and feeding when exposed to oil. It is possible that the reduced swimming activity observed may be due to a narcotic effect of the oil. Furthermore, early stage sea urchin larvae showed increased mortality when exposed to oil while the older larvae did not, indicating a stage specific toxicity to oil for sea urchin larvae. The combination of global drivers and oil pollution acted additively on growth for both sea urchin and shrimp larvae. The impact of combined drivers on the size of shrimp larvae was equal the sum of the negative impacts observed for each driver: a 5 % reduction when exposed to OA and OW, a 9 % reduction when exposed to oil, and a cumulative 15 % reduction when exposed to all stressors. Similarly, the impact of combined drivers on the size of sea urchin larvae was equal to the sum of the negative impacts observed for each driver: a 14 % reduction when exposed to OA, a 9 % reduction when exposed to oil, and a 21 % reduction when exposed to all drivers. Therefore, the study demonstrated the additive physiological effects of OA, OW and a contaminant, and indicated that larval (sea urchin and shrimp) resilience to future changes (i.e. pollution) could be greatly reduced if larvae were already energy limited and severely stressed (reduced development) as a result of exposure to the global drivers. This study therefore shows the importance that the effective management of local drivers such as oil pollution could have against the backdrop of OA and OW, and emphasises that it is important to study impacts of toxicants, such as an oil pollution, in the context of predicted changes in the environment, as OW and OA are becoming major concerns. Finally, the fact that some local and global drivers seem to act additively should encourage local managers to act on local driver regulations, to obtain positive effects on local populations and environment and thereby rendering them more resilient to the negative impacts of future global drivers.
189

Calibration-free Spectrophotometric Measurements of Carbonate Saturation States in Seawater

Cuyler, Erin E. 01 November 2017 (has links)
This work describes efforts to improve methodologies and instrumentation for investigation of the marine CO2 system. In the first section of my thesis, a method was developed that provides simple, calibration-free measurements of seawater carbonate saturation states (Ωspec) based solely on the use of a laboratory spectrophotometer. Measurements of pH are made in paired optical cells, one with and one without added nitric acid. The amount of added nitric acid is determined through the direct proportionality between nitrate concentration and UV absorbance. After an initial calibration, the method is calibration-free and requires no volumetric or gravimetric analyses thereafter. Saturation state measurements can be obtained in twelve minutes and attain Global Ocean Acidification Observing Network accuracy goals over a wide range of conditions. This simple one-step measurement protocol is ideal for monitoring ocean acidification conditions in coastal areas, fish hatcheries and shellfish farms. The second section of my thesis outlines the development of a next-generation handheld photometer for field measurements of seawater pH. The hand-held instrument is simple to use, inexpensive, and has a pH measurement accuracy of ±0.01. Each photometer is calibrated by relating pH-indicator absorbance ratios (RB) obtained with the broadband photometer to indicator absorbance ratios (RN) obtained with a high quality, narrowband scanning spectrophotometer. The RB vs RN relationship for each photometer is entered into the instrument’s software, providing discrete, real-time pH observations from measurements of RB, salinity and temperature. Measurement accuracy is assessed through comparisons of photometer pH with pH observations obtained using standard measurement procedures and high-quality spectrophotometers. The targeted user-groups for these instruments include middle and high school students, citizen scientists, and resource managers
190

The metabolic physiology of early stage Argyrosomus japonicus with insight into the potential effects of pCO2 induced ocean acidification

Edworthy, Carla January 2018 (has links)
Ocean acidification is a phenomenon associated with global change and anthropogenic CO2 emissions that is changing the chemistry of seawater. These changes result in elevated pCO2 and reduced pH in seawater and this is impacting marine organisms in various ways. Marine fishes are considered generally tolerant to conditions of ocean acidification; however, these assumptions are based on juvenile and adult fish tolerance and the larval stages have not been frequently assessed. Furthermore, it has been suggested that temperate species, particularly those with an estuarine association, may be tolerant to variable CO2 and pH. This study used an eco-physiological approach to understand how the early life stages of Argyrosomus japonicus, an estuarine dependent marine fisheries species found in warm-temperate regions, may be impacted by ocean acidification. The metabolic response of early stage larvae (hatching to early juvenile stage) was assessed under conditions of elevated pCO2 and reduced pH in a controlled laboratory setting. Small volume static respirometry was used to determine the oxygen consumption rate of larvae raised in three pCO2 treatments including a low (pCO2 = 327.50 ± 80.07 µatm at pH 8.15), moderate (pCO2 477.40 ± 59.46 µatm at pH 8.03) and high treatment (PCO2 910.20 ± 136.45 µatm at pH 7.78). These treatment levels were relevant to the present (low) and projected conditions of ocean acidification for the years 2050 (moderate) and 2100 (high). Prior to experimentation with ocean acidification treatments, baseline metabolic rates and diurnal variation in oxygen consumption rates in early stage A. japonicus was determined. Distinct ontogenetic structuring of metabolic rates was observed in early stage A. japonicus, with no cyclical fluctuations in metabolic rate occurring during the 24 hour photoperiodic cycle. Pre-flexion larvae showed no metabolic response to ocean acidification treatments; however post-flexion stage larvae showed metabolic depression of standard metabolic rate in the moderate (32.5%) and high (9.5%) pCO2 treatments (P = 0.02). Larvae raised in the high pCO2 treatment also showed high levels of mortality with no individuals surviving past the post-flexion stage. Larvae raised in the moderate pCO2 treatment were unaffected. This study concluded that ocean acidification conditions expected for the end of the century will have significant impacts on the metabolism of early stage A. japonicus, which may result in reduced growth, retardation of skeletal development and ultimately survival as a result of increased mortality. Furthermore, the timing of reduced metabolic scope will significantly impact the recruitment ability of A. japonicus larvae into estuarine habitats. This could ultimately impact the sustainability of A. japonicus populations. Most importantly, this study highlighted the need to consider the combined effect of ontogeny and life-history strategy when assessing the vulnerability of species to ocean acidification.

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