Graduation date: 2000

Human activities have contributed to the increase in atmospheric greenhouse gases such as carbon dioxide (CO2). This anthropogenic gas emission has led to a rise in the average Earth temperature. Moreover, the ocean constitutes the major sink for anthropogenic CO2 and its dissolution in surface waters has already resulted in an increase of seawater acidity since the beginning of the industrial revolution. This is commonly called ocean acidification. The increase in water temperature could induce modifications of the physical and chemical characteristics of the ocean. Also, the structure and the functioning of marine ecosystems may be altered as a result of ocean acidification. Phytoplankton productivity is one of the primary controls in regulating our climate, for instance via impact on atmospheric CO2 levels. Coccolithophores, of which Emiliania huxleyi is the most abundant species, are considered to be the most important pelagic calcifying organisms on Earth. Coccolithophores are characterized by calcium carbonate platelets (coccoliths) covering the exterior of the cells. They form massive blooms in temperate and sub-polar oceans and in particular along continental margin and in shelf seas. The intrinsic coupling of organic matter production and calcification in coccolithophores underlines their biogeochemical importance in the marine carbon cycle. Both processes are susceptible to change with ocean acidification and warming. Coccolithophores are further known to produce transparent exopolymer particles (TEP) that promote particle aggregation and related processes such as marine snow formation and sinking. Thus, the impact of ocean warming and acidification on coccolithophores needs to be studied and this can be carried out through a transdisciplinary approach. The first part of this thesis consisted of laboratory experiments on E. huxleyi under controlled conditions. The aim was to estimate the effect of increasing water temperature and acidity on E. huxleyi and especially on the calcification. Cultures were conducted at different partial pressures of CO2 (pCO2); the values considered were 180, 380 and 750 ppm corresponding to past, present and future (year 2100) atmospheric pCO2. These experiments were conducted at 13°C and 18°C. The cellular calcite concentration decreases with increasing pCO2. In addition, it decreases by 34 % at 380 ppm and by 7 % at 750 ppm with an increase in temperature of 5°C. Changes in calcite production at future pCO2 values are reflected in deteriorated coccolith morphology, while temperature does not affect coccolith morphology. Our findings suggest that the sole future increase of pCO2 may have a larger negative impact on calcification than its interacting effect with temperature or the increase in temperature alone. The evolution of culture experiments allows a better comprehension of the development of a bloom in natural environments. Indeed, in order to predict the future evolution of calcifying organisms, it is required to better understand the present-day biogeochemistry and ecology of pelagic calcifying communities under field conditions. The second part of this dissertation was dedicated to results obtained during field investigations in the northern Bay of Biscay, where frequent and recurrent coccolithophorid blooms were observed. Cruises, assisted by remote sensing, were carried out along the continental margin in 2006 (29 May – 10 June), 2007 (7 May – 24 May) and 2008 (5 May – 23 May). Relevant biogeochemical parameters were measured in the water column (temperature, salinity, dissolved oxygen, Chlorophyll-a and nutrient concentrations) in order to determine the status of the bloom at the time of the different campaigns. Calcification has been shown to be extremely important in the study area. In addition, TEP production was significant at some stations, suggesting that the northern Bay of Biscay could constitute an area of important carbon export. Mortality factors for coccolithophores were studied and the first results of lysis rates measured in this region were presented. Results obtained during culture experiments and comparison with data reported in the literature help to better understand and to predict the future of coccolithophores in a context of climate change. Data obtained during either culture experiments or field investigations allowed a better understanding of the TEP dynamics. Finally, the high lysis rates obtained demonstrate the importance of this process in bloom decline. Nevertheless, it is clear that we only begin to understand the effects of global change on marine biogeochemistry, carbon cycling and potential feedbacks on increasing atmospheric CO2. Thus, further research with a combination of laboratory experiments, field measurements and modelling are encouraged.

Despite the spatial significance of Canadas boreal forest, there is very little known about greenhouse gas emissions within it. The primary objective of this project was to study the atmosphere-soil exchange of CH4 and N2O in the boreal forest of central Saskatchewan. In the summers of 2006 and 2007, greenhouse gas emissions were measured along transects in three different mature forest stands (trembling aspen, black spruce and jack pine) using a sealed chamber method. In addition, the gross rates of mineralization and nitrification, and the relative contribution of nitrification and denitrification to N2O emissions, were measured at the trembling aspen site using a stable isotope technique in which 15N-enriched nitrate and ammonium were injected into intact soil cores. The amount of 14N found in the labeled pools was used to measure the gross rates, and the amount of 15N found in the emitted N2O was used to determine the relative contribution of the different N pathways to total N2O emissions. Results indicated that the jack pine and black spruce sites were slight sinks of CH4 (-1.23 kg CH4-C ha-1 yr-1and -0.17 kg CH4-C ha-1 yr-1 respectively in 2006 and -0.95 kg CH4-C ha-1 yr-1and 0.45 kg CH4-C ha-1 yr-1 respectively in 2007), whereas the trembling aspen site was a net source (46.7 kg CH4-C ha-1 yr-1 in 2006 and 196.0 kg CH4-C ha-1 yr-1 in 2007). All three sites had very low cumulative N2O emissions, ranging from -0.02 to 0.14 kg N2O-N ha-1 yr-1 in both years. Of the environmental controls examined for CH4, consumption at the jack pine site was correlated positively with organic carbon and negatively with water-filled pore space. Black spruce CH4 emissions were correlated negatively with both organic carbon and clay content, and emissions at the trembling aspen site were positively correlated with soil temperature and organic carbon, while also related to the presence of standing water (2006 and 2007 had very high precipitation, causing a high water table and ponding in depressions). The N2O emissions were not correlated with any of the environmental parameters measured at the jack pine or black spruce sites, but clay content was positively related to emissions at the trembling aspen site. The 15N results indicated that N cycling at the trembling aspen site was very rapid, allowing little N to escape the system as N2O; the majority of emissions that did occur were due to a nitrification-related process.

Esta tesis se ha desarrollado como parte del proyecto VULCAN (Vulnerabibilty assessment of shrubland ecosystems under climatic changes), un proyecto de investigación llevado a cabo en seis ecosistemas de matorrales europeos (Gales-Reino Unido, Dinamarca, Holanda, Hungría, Cerdaña-Italia y Catalunya-España), distribuidos en un gradiente de temperatura (8.2 - 15.6 ºC) y precipitación (511 - 1427 mm). En ella se han incluido datos recogidos durante el periodo 1999-2005.El objetivo global de la investigación fue el de aportar conocimientos y reducir incertidumbres acerca del funcionamiento de los matorrales europeos y del rol que pueden desempeñar éstos como fuente o sumidero de carbono bajo la perspectiva del cambio climático.En las parcelas de los diferentes países se instalaron novedosas manipulaciones experimentales para aumentar la temperatura y para reducir el agua disponible en campo, simulando los efectos del cambio climático previstos para las décadas futuras. En este trabajo se han estudiado los efectos de los tratamientos en la diversidad vegetal, en la productividad primaria aérea, así como en la fenología del crecimiento y en la elongación de ramas de las especies vegetales dominantes de los ecosistemas arbustivos europeos. Además en las parcelas experimentales de Garraf se investigó la sensibilidad de los procesos relacionados con la captación de carbono por la vegetación a nivel de hoja (fluorescencia, fotosíntesis, conductancia estomática) y se estudió la respuesta de la floración no primaveral de las dos especies arbustivas dominantes, Erica multiflora y Globularia alypum.Los efectos del cambio climático a nivel de ecosistema fueron complejos debido a la gran variabilidad de respuestas de las plantas a los tratamientos según las variables medidas, las especies, estaciones u años, sitios y periodos de experimentación.En Garraf, una zona que sufrió un incendio en 1994, encontramos una clara reducción en el número de especies por transecto en las parcelas de sequía respecto a las control, sin embargo no encontramos efectos similares en el resto de Europa lo que sugiere que la riqueza de especies en comunidades en proceso de recuperación después de una perturbación puede ser especialmente sensible al cambio climático respecto a otras comunidades en estadios más maduros. Concretamente, encontramos que los tratamientos de calentamiento y sequía redujeron la habilidad competitiva de Pinus halepensis (germinador obligado) frente a los arbustos rebrotadores y que la estrategia en el uso del agua pudo ayudar a G. alypum a mantener una posición dominante en las parcelas de sequía de Garraf. En los países con menor aridez las respuestas de la biomasa anual acumulada al calentamiento fueron más positivas sin embargo, el hecho de que también encontremos especies mediterráneas como E. multiflora que respondieron positivamente al calentamiento, junto con el hecho de que fenómenos extremos como la ola de calor Europea en 2003 redujeran la productividad primaria, matizan la hipótesis de que sea en los ecosistemas más fríos en los que el calentamiento global de lugar a una mayor absorción de carbono. Concretamente, la respuesta a los tratamientos de la biomasa a nivel de cubierta en Garraf pudo anularse debido a respuestas opuestas de las especies dominantes. En este estudio, el gradiente geográfico que dibuja los matorrales estudiados no determinó la sensibilidad de las especies al calentamiento ni la intensidad de la respuesta en lo que a fenología del crecimiento y elongación de ramas se refiere. La fenología del crecimiento de algunas especies mediterráneas fue tan sensible al calentamiento experimental (se avanzó) como algunas especies de distribución más septentrional.Aunque nuestro estudió mostró que la floración de E. multiflora y G. alypum, que tiene lugar en otoño-invierno, dependió en gran medida de la lluvia acumulada y su distribución durante el periodo primavera-verano, los tratamientos experimentales no afectaron esta variable. Estos resultados se explican en parte por la mayor variación de humedad que hubo entre años respecto a la diferencia de humedad que hubo entre las parcelas de sequía y controles. / This PhD thesis has been developed as part of the VULCAN project (Vulnerabibilty assessment of shrubland ecosystems during climatic changes), a research project conducted in six European shrublands (Wales, United Kingdom, Denmark, Holland, Hungary, Italy-Cerdagne and Catalonia-Spain), distributed in a gradient of temperature (8.2 - 15.6 ° C) and precipitation (511 - 1427 mm). It includes data collected during the 1999-2005 period. The overall objective of the research was to provide knowledge and reduce uncertainties about the functioning of the shrublands and the role that they can play as a source or sink of carbon under the prospect of climate change. At each site, novel experimental manipulations were installed to increase the temperature and to reduce the water available in field, simulating the effects of climate change projected for the future decades.In this work we have studied the effects of treatments on plant diversity, aboveground primary productivity, as well as on the phenology of growth and on the shoot elongation of dominant species. In addition, in Garraf we investigated other processes at leaf level such fluorescence, photosynthesis, stomatal conductance and other at plant level such the response of the non-spring flowering species, Erica multiflora and Globularia alypum. The effects of climate change at the ecosystem level were complex because of the great variability of plant responses to treatment according to the variables, species, seasons or years, sites and periods of experimentation. In Garraf, an area which suffered a fire in 1994, we found a clear reduction in the number of species per transect on drought plots, but no similar effects were found in the rest of Europe, suggesting that communities in process of recovery after disturbance can be particularly sensitive to climate change compared to other communities in more mature stages. Specifically, we found that the experimental treatments reduced the competitive ability of the obligate seeder Pinus halepensis against native resprouter shrubs and that the water spender strategy of G. alypum may allow this species to maintain a dominant position in drought plots in Garraf. In sites with lower aridity, the responses of the annual accumulated biomass to warming were more positive. However, the fact that we found Mediterranean species such as E. multiflora responding positively to global warming, coupled with the fact that extreme events such as the European heat wave in 2003 reduced primary productivity, challenge the assumption that it is in colder ecosystems where global warming will result in a greater carbon sequestration. Specifically, opposite responses of the dominant species could cancel out a clear response of biomass accumulation at canopy level in Garraf.In this study, the geographical gradient did not determine the susceptibility of the species or the intensity of the response of the phenology of growth and shoot elongation to the warming treatment. The phenology of growth of some Mediterranean species was very responsive to warming treatment (mainly advances) as some species of northernmost distribution. The study also shows that although flowering of E. multiflora and G. alypum, which takes place in the autumn-winter, depended largely on the accumulated rainfall and its distribution during the spring-summer period, the experimental treatments did not affect this variable. These results are explained in part by the greater range of soil moisture between years than between drought and controls plots.

Despite the spatial significance of Canadas boreal forest, there is very little known about greenhouse gas emissions within it. The primary objective of this project was to study the atmosphere-soil exchange of CH4 and N2O in the boreal forest of central Saskatchewan. In the summers of 2006 and 2007, greenhouse gas emissions were measured along transects in three different mature forest stands (trembling aspen, black spruce and jack pine) using a sealed chamber method. In addition, the gross rates of mineralization and nitrification, and the relative contribution of nitrification and denitrification to N2O emissions, were measured at the trembling aspen site using a stable isotope technique in which 15N-enriched nitrate and ammonium were injected into intact soil cores. The amount of 14N found in the labeled pools was used to measure the gross rates, and the amount of 15N found in the emitted N2O was used to determine the relative contribution of the different N pathways to total N2O emissions. Results indicated that the jack pine and black spruce sites were slight sinks of CH4 (-1.23 kg CH4-C ha-1 yr-1and -0.17 kg CH4-C ha-1 yr-1 respectively in 2006 and -0.95 kg CH4-C ha-1 yr-1and 0.45 kg CH4-C ha-1 yr-1 respectively in 2007), whereas the trembling aspen site was a net source (46.7 kg CH4-C ha-1 yr-1 in 2006 and 196.0 kg CH4-C ha-1 yr-1 in 2007). All three sites had very low cumulative N2O emissions, ranging from -0.02 to 0.14 kg N2O-N ha-1 yr-1 in both years. Of the environmental controls examined for CH4, consumption at the jack pine site was correlated positively with organic carbon and negatively with water-filled pore space. Black spruce CH4 emissions were correlated negatively with both organic carbon and clay content, and emissions at the trembling aspen site were positively correlated with soil temperature and organic carbon, while also related to the presence of standing water (2006 and 2007 had very high precipitation, causing a high water table and ponding in depressions). The N2O emissions were not correlated with any of the environmental parameters measured at the jack pine or black spruce sites, but clay content was positively related to emissions at the trembling aspen site. The 15N results indicated that N cycling at the trembling aspen site was very rapid, allowing little N to escape the system as N2O; the majority of emissions that did occur were due to a nitrification-related process.

Human large-scale use of coal, oil, natural gas and other fossil fuels, which emit large quantities of energy use is caused by the greenhouse effect of greenhouse gases, including carbon dioxide increases rapidly, is the culprit of global warming. Man type and species of global warming has brought the threat of the living environment, how to effectively slow down global warming has become the man to face critical issues. According to Taiwan's greenhouse gas emissions from all sectors data show that the transport sector with a significant contribution to greenhouse gas emissions, developed with the vehicle industry, motor vehicles have become the main transport means of transport to daily life, but also resulted in major metropolitan areas and air pollution from carbon dioxide, improve air quality and reduce carbon emissions, should have to be propaganda vehicle maintenance and regular inspection of work, vehicle maintenance facilities for the engine than coke will effectively reduce unnecessary vehicle emissions and pollution, with a view to sustainable human development. This study to collect relevant information through expert interviews, sorting out the market viability of the Automotive engine carbon removal methods are "bubble-type engine than coke," the "trickle engine program than coke" and "In addition to product hydrogen aircraft engine Carbon Programme "of three. And to identify factors that impact assessment, "the cost of implementation", "when applied to pollution assessment," "clear the effect of coke", "engine damage effects" and "ease of handling," and five. Main and analytic theory, experts in the field to conduct the carbon removal of the vehicle engine is assessed for the valid questionnaires, the use of AHP Analysis Method Comparison of the order of priority or importance, to find consistency through the whole management of the common point of view. Comprehensive management and access to the whole study found that industry, government, science and other 12 experts were assessing the overall level of the importance of the five ranking for the "impact of engine damage," the most important, were "clear the effect of coke," " when applied to pollution assessment, "" implementation costs "," easy operation "of the last. The engine in the current market feasible than carbon technology, the experts unanimously agree that the "hydrogen aircraft engine program than coke," the most advantage of the actual promotion of environmental protection that, the Government Ying Ying Zao Leung good conduct political Peihehuanjing, provide economic incentives to encourage people to Automotive engine carbon removal and counseling industry to promote environmental protection measures. The research results could serve as references for the Government's future vehicles and the carbon reduction policies.

Jellyfish blooms create problems worldwide, which may increase with global warming, water pollution, and over-fishing. Benthic polyps (scyphistomae) asexually produce buds and small jellyfish (ephyrae), and this process may determine the population size of the large, swimming scyphomedusae. Environmental factors that affect the asexual reproduction rates include food, temperature, salinity, and light. In the present study, polyps of Aurelia aurita (L.), originated from Tapong Bay, southwest Taiwan, were studied in different combinations of temperatures (T), light intensities (L), and salinities (S). In the T (20, 25, 30¢XC) ¡Ñ L (372, 56, and 0 lux) experiment which was with a 12 h light-12 h dark photoperiod, production of new buds decreased with warmer temperatures and stronger light intensity. Warm temperatures accelerated strobilation and increased the daily production of ephyrae. The proportion of ephyrae to total asexual reproduction (new buds + ephyrae) increased dramatically in warmer temperatures and stronger light. Survival period was reduced at the highest temperature. Strobilation did not occur at the lowest temperature in darkness. All measures of total asexual reproduction indicated that medium to high temperatures would lead to faster production of more jellyfish; however, continuous high temperatures might result in high polyp mortality. Light intensity affected asexual reproduction less than did temperature, only significantly accelerating the strobilation rate. Because the interactive effects of light and temperature were significant for polyp survival time and the production of jellyfish per polyp, combined light and temperature effects are likely important for strobilation in situ. In the T (27, 31, 35¢XC) ¡Ñ S (25, 30, and 35) experiment which was in dark environment, production of new buds decreased with higher temperatures and salinity. The proportion of ephyrae to total asexual reproduction (new buds + ephyrae) increased with warmer temperatures, but survival period was reduced at the highest salinity, and strobilation was substantially reduced, even though the temperature was warmer compared to the T ¡Ñ L experiment. Salinity affected asexual reproduction less than did temperature, only significantly affecting production of new buds, and slightly affecting survival period and the proportion of ephyrae to total asexual reproduction. According to these two experiments, warmer temperature may accelerate strobilation in light condition and lead to better yield of swimming jellyfish, however continuously warm temperature would reduce the yield by decreasing budding and higher mortality. Complete dark led to much less strobilation, especially at low temperatures, suggesting that the existence of light might be more important than light intensity. The effects of salinity on asexual reproduction were not as conspicuous as that of temperature and light.

Thesis (Masters) -- University of Ballarat, 2008. / Submitted in partial fulfillment of the requirements for the degree of Master of Arts (Visual Arts), Arts Academy. Bibliography: leaves 56-58.

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Environmental Sciences." Includes bibliographical references (p. 103-106).

Master's thesis. / Format: PDF. Bibl.