Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-01-26T18:42:50Z No. of bitstreams: 0 / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-01-29T11:01:37Z (GMT) No. of bitstreams: 0 / Made available in DSpace on 2018-01-29T11:01:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-06-09 / - / Bacteria are important components of the food web structure in aquatic ecosystems in which they influence the flow of carbon and energy. Populations of bacteria in these ecosystems comprise a diverse spectrum of individual cells able to respond to many factors such as nutrient supply, temperature and virus infection, which regulate bacterial life and death. Bacterial death is a key cellular event involved in the control and production of bacteria in aquatic ecosystems with functional meaning in the carbon and nutrient cycles. Therefore, the study of bacterial structural features and cellular mechanisms underlying bacterial death is crucial to understand processes affecting the entire population. However, both bacterial structure and cellular events of death in aquatic ecosystems are still poorly understood. In the present work, we used single cell approaches to study the structural organization of bacteria as well as to characterize cellular processes of death in these organisms. First, by using fluorescence and transmission electron microscopy (TEM), we provided a general panorama of how microscopy techniques, especially TEM, are powerful tools to understand bacterial structure and their responses to environmental stresses. We showed that bacteria from aquatic ecosystems have remarkable ultrastrutural diversity with components such as bacterial envelope of individual cells differing in structure within the same population. Second, we sought to identify and characterize mechanisms of bacterial cell death. Because our TEM analyses revealed morphological signs of apoptosis, a type of program cell death (PCD), in aquatic bacteria directly collected from natural ecosystems, we applied different techniques to detect apoptosis in bacteria cultured from natural samples. We used TEM as well as different probes to detect this type of PCD in cultured bacteria exposed to increased temperature and viral infection, which are recognized inducers of bacterial death. TEM showed, in both situations, ultrastructural changes indicative of apoptosis, such as cell retraction and condensation, similar to those reported for eukaryotic cells. Assays for membrane permeability, DNA fragmentation, phosphatidilserine exposition and caspase activation were significantly increased in treated bacteria compared to the control group. Altogether, our data demonstrate, for the first time, that PCD occur in aquatic bacteria, and that this event may be a basic mechanism for regulation of bacterial communities in these ecosystems.

Climate change, global warming and anthropogenic disturbances are threatening freshwater ecosystems globally. The protection and preservation of freshwater environments, its biodiversity and all of its services for human well-being requires comprehensive knowledge of the impacts that climate change and anthropogenic disturbances have on freshwaters and freshwater species. In-depth knowledge needed for conservation strategies can be established through versatile assessments. Quantitative assessments and the investigation of prevailing environmental relationships within ecosystems constitute the basis for sustaining freshwater systems. However, it is a great challenge to quantify the multifaceted effects of climate change and to broaden the understanding of complex environmental relationships. This thesis aims at contributing to an extension of the understanding of climate change impacts on freshwater ecosystems and environmental relationships, which implies the provision of useful guidelines for the protection and preservation of freshwaters. For this, various statistical approaches based on comprehensive data sets are applied at different scales, ranging from local to global assessments. In particular, five research studies investigating the (1) water quality-nutrient and temperature relationships in European lakes, (2) drivers of freshwater fish species distributions across varying scales in the Danube River delta, (3) globally derived thermal response curves and thermal properties of native European freshwater species, (4) differences between thermal properties derived from native and global range data, and (5) thermal performances of freshwater fish species for different life stages and different global future dispersal scenarios are presented to address the effects of environmental change. Main results of this thesis comprise various aspects of conservation implications and planning. (i) The first study outlines drivers influencing water quality through studying multi-dimensional relationships and compares different modelling techniques in order to outline models that are suitable for the identification of complex driver interactions. (ii) The second study addresses scale effects on the performance of species distribution models, which are commonly used for assessments of climate change impacts, and identifies key predictors driving distributions for the varying scales and studied species. (iii) The third study parameterizes thermal responses of species from different taxonomic groups and assesses the potential resilience in terms of warming tolerance and additional thermal properties as well as the influence of future rising temperatures on current distributions. (iv) The fourth study quantifies the differences in thermal response curves and thermal properties for freshwater fishes derived from global and continental data in order to clarify the need for using global range data in studies making suggestions for conservation planning. (v) The last study estimates the impact of changing climatic conditions on species distribution ranges of two fish species for different time periods by including biotic information about thermal performances for various life stages. Overall, this thesis contributes to the broad field of studying consequences and impacts of climate change on freshwater ecosystems. By applying statistical methods tailored to the underlying investigations, useful implications for conservation planning are derived.

The health of freshwater aquatic systems, particularly stream networks, is mainly influenced by water temperature, which controls biological processes and influences species distributions and aquatic biodiversity. Thermal regimes of rivers are likely to change in the future, due to climate change and other anthropogenic impacts, and our ability to predict stream temperatures will be critical in understanding distribution shifts of aquatic biota. Spatial statistical network models take into account spatial relationships but have drawbacks, including high computation times and data pre-processing requirements. Machine learning techniques and generalized additive models (GAM) are promising alternatives to the SSN model. Two machine learning methods, gradient boosting machines (GBM) and Random Forests (RF), are computationally efficient and can automatically model complex data structures. However, a study comparing the predictive accuracy among a variety of widely-used statistical modeling techniques has not yet been conducted. My objectives for this study were to 1) compare the accuracy among linear models (LM), SSN, GAM, RF, and GBM in predicting stream temperature over two stream networks and 2) provide guidelines in choosing a prediction method for practitioners and ecologists. Stream temperature prediction accuracies were compared with the test-set root mean square error (RMSE) for all methods. For the actual data, SSN had the highest predictive accuracy overall, which was followed closely by GBM and GAM. LM had the poorest performance overall. This study shows that although SSN appears to be the most accurate method for stream temperature prediction, machine learning methods and GAM may be suitable alternatives.

No description available.

Achieving global water sustainability through a resilient international legal architecture presents one of the most pressing challenges within our resource finite planet. A staggering 42 percent of the total land area of the earth is covered by transboundary river basins, where more than 40 percent of the global population lives and depends on the ecosystem services of the 286 transboundary river basins and 200 transboundary aquifers stretching across the political boundaries of 151 countries. There is already evidence of water resources becoming a source of conflict in many regions and constraining a whole myriad of securities – climate, human, environmental, food, economic, energy – on various levels of society. The international legal architecture to manage this critical natural resource is the overarching area of inquiry in this thesis, and requires improvement to address current and predicted future transboundary water challenges, conflicts and strengthen cooperation. Despite the establishment of around 690 river basin treaties, many of these agreements completely miss or provide unclear provisions on principles and rules of international water law. Until recently there was no legally binding global treaty on transboundary watercourses and customary international law has provided the default rules in the absence of agreements and facilitated the re-interpretation of older agreements in accordance with the Vienna Convention on the Law of Treaties. Now there are potentially two global treaties, with the recent entry into force of the 1997 UN Watercourses Convention and the global opening up of the 1992 pan-regional United Nations Economic Commission for Europe (UNECE) Water Convention, to all UN member states. There is also a plethora of other international environmental legal and non-legally binding instruments, indirectly addressing international law relevant to transboundary watercourses and freshwater ecosystems. Legal regimes for the protection and use of international river basins cannot be interpreted and applied in isolation from other relevant norms of international environmental and general international law. This thesis seeks to understand the rising role and contribution of regional approaches relevant to international law on transboundary watercourses and freshwater ecosystems. More specifically it explores the contribution of the UNECE Water Convention and other relevant UNECE environmental instruments as a structurally distinctive ‘regime’. This thesis introduces a novel conception of a broader ‘UNECE water regime’ which includes the Water Convention, the Convention on Access to Information, Public Participation in Decision-making and Access to Justice (Aarhus Convention), the Convention on Transboundary Environmental Impact Assessment (Espoo Convention), the Convention on the Transboundary Effects of Industrial Accidents, as well as their protocols and non-binding instruments. This research demonstrates how these instruments and their institutions can be interpreted and understood to form a common framework of rules, principles and approaches which fills critical gaps in basin treaties, and collectively contributes to the clarification and development of international law on transboundary watercourses and freshwater ecosystems. This analysis also explores institutional interaction and coordination between and beyond the UNECE pan-regional agreements, as well as the role of soft law or non-binding instruments, and state and non-state actors in the regime. This thesis seeks to contribute to a more coherent understanding of the relationship between the UNECE water regime, international water law, international environmental law and general international law. The UNECE water regime has contributed to clarifying many of the cornerstone rules and principles of international water law and it is argued that the UNECE water regime is lex specialis, which can and mostly does go beyond the UN Watercourses Convention. The UNECE water regime has also arguably spearheaded a paradigm shift in international water law, which sees it moving beyond its historically predominant focus on issues of transboundary impact and utilisation towards a stronger ecosystem orientated approach to environmental protection and equitable use of transboundary river basins. This research identifies key elements of an ecosystem approach, drawing from international environmental and international water law and demonstrates how the ecosystem approach, including ecosystem services, as supported by the UNECE water regime, affects interpretation of international water law towards enhancing ecosystem protection and intra-state equity. This research also explores how the UNECE regime goes beyond what exists elsewhere in international law and international water law on public participation and access to justice. Finally, this research examines the contribution of the UNECE regime vis-à-vis international and European Union water law, across the spectrum of pan-European river basins, especially focusing on the Danube, Sava and Western Bug basins. The UNECE water regime is the most evolved pan-regional regime of its kind, providing ambitious detailed standards and clarification of rules and principles relevant to transboundary watercourses and freshwater ecosystems. It also provides a valuable model of institutional cooperation, progressively engaging state and non-state actors. As this regime takes steps towards realising its global ambition, with almost all instruments now open to all UN member states, and the recent accession by Chad to the Water Convention, this analysis demonstrates why this is predominantly a positive endeavour but also highlights potential challenges and hurdles. This research thus explores the implications and benefits of the UNECE’s rising role in strengthening the international legal architecture to protect the world’s fragile transboundary watercourses and freshwater ecosystems.

Els sistemes aquàtics continental representen un dels ecosistemes més amenaçats a nivell mundial, com a conseqüència de l'ús intensiu quel'home en fa. La conca del Guadiana no està lliure d'aquestes pressions antròpiques. Les grans infraestructures hidràuliques i l'escorrentia provinent de l'agricultura són només exemples dels greus problemes que pateix la conca. Aquests problemes es fan especialment palesos en la zona alta de la conca, on l'escassetat d'aigua no fa més que agreujar el problema.Tot això ha generat la necessitat urgent d'avaluar l'estat de conservació d'aquests ecosistemes aquàtics continentals, poder determinar la mesura i la magnitud de les pertorbacions que els estan afectant i així proposar mesures de gestió destinades a restaurar-ne la integritat ecològica. El principal objectiu que presenta aquest és determinar els patrons de distribució de les comunitats de algals (amb una menció especial en el grup de les diatomees) i de les seves causes en la conca del Guadiana i associades, amb la finalitat d'establir i proposar eines que permetin avaluar l'estat de conservació de les masses d'aigua d'aquestes conques. / In many parts of the world freshwater ecosystems are intensely modified and degraded by human activities. Rivers have been altered since historical times, but such modifications have intensified in the last century. Water extraction and heavily regulated reservoirs are spread disturbances in the Guadiana network. Drainage from agricultural land in river systems results in large inputs of nitrates and phosphates that eutrophy river waters. Inputs of fertilizers and water extraction are especially remarkable in the North-East Guadiana watershed. The development of tools to assess ecological status of water bodies has been a key issue in the management of the freshwater ecosystems in the last decades in order to protect and restore the biological integrity of ecosystems. The present study aims to determine distributional patterns of benthic algae communities (with a special attention on diatom microflora) and their causes in Guadiana and associated watersheds in order to establish tools for assessing the conservation status of the water bodies in those watersheds.

Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2018-02-28T17:53:43Z No. of bitstreams: 1 Mestrado Zocatelli_2005.pdf: 2359099 bytes, checksum: 003a12dc52353f60ebd20e0474552e46 (MD5) / Made available in DSpace on 2018-02-28T17:53:43Z (GMT). No. of bitstreams: 1 Mestrado Zocatelli_2005.pdf: 2359099 bytes, checksum: 003a12dc52353f60ebd20e0474552e46 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Institut de Rechèrche pour le Développement / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geoquímica, Niterói, RJ / A composição da matéria orgânica em sedimentos de lagos nos fornece informações essenciais para reconstrução de condições paleoambientais. A análise dos fenóis da lignina tem se tornado uma importante ferramenta na quantificação e na avaliação do comportamento do material vegetal produzido em ambientes aquáticos e em suas bacias de drenagem. Da mesma forma, os pigmentos sedimentares são utilizados para avaliação da paleoprodutividade. Foram analisados dois testemunhos coletados na Lagoa do Caçó, um no centro da lagoa e outro na margem, representando aparentemente uma seqüência sedimentar contínua datada de aproximadamente 21.000 anos 14C A.P. Esta lagoa está localizada em uma área costeira influenciada pela zona de convergência intertropical (ZCIT), representando um potencial sítio para estudos paleoambientais. Foram quantificados onze fenóis, em amostras de testemunhos, em possíveis fontes de matéria orgânica e em sedimentos superficiais. Estes resultados foram comparados com dados secundários sobre a mineralogia dos sedimentos, de pólen e de diatomáceas dos mesmos testemunhos para a verificação da aplicação destes fenóis como um potencial traçador de eventos paleoambientais. A oscilação do nível d’água da lagoa foi verificada através da variação dos valores do total de fenóis oriundos da lignina (λ), sendo registrado os maiores valores na zona marginal e relacionados a sedimentação das comunidades macrofíticas. Entre os compostos analisados o siringaldeído (Sl) do grupo S foi relacionado à ocorrência de plantas aquáticas típicas de brejo marcando o início de uma sedimentação lacustre. O ácido felúrico (Fd) do grupo C foi o composto que melhor marcou a ocorrência de bancos de macrófitas próximo à margem enquanto o p-hidroxibenzaldeído (pBl) se destacou como um bom traçador de perifíton. A ocorrência destes compostos em diferentes concentrações caracterizaram alternâncias na composição e quantidade das comunidades aquáticas relacionando-a a eventos climáticos. Os eventos de clima úmido influenciaram diretamente a inundação da região marginal da lagoa, tornando-a propícia a produtividade aquática e com isto aos maiores valores de λ. Os resultados dos fenóis da lignina apresentaram em geral maior concordância com os resultados de diatomáceas do que de pólen. Finalmente, a partir da composição orgânica do perfil sedimentar localizado na margem podemos sugerir a seguinte sucessão ecológica da base ao topo: (I) ambientes típicos de dunas; (II) transição de dunas para um ambiente deposicional tipo brejo; (III) inundação desta região e colonização por macrófitas; (IV) aumento do nível da lagoa tornando esta região limnética. / The organic matter content of lake sediments serves to reconstruct the paleoenvironmental conditions. Lignin phenols analyse have become a powerful quantitative approach for the fate of vascular plant produced in aquatic environments and its catchments. In addiction, sedimentary pigments were evaluated in other to measure the paleoproductivity. Two cores were collected in the Lagoa do Cacó, one in the center of the lagoon and another on the margin, representing a continuous sedimentary sequence dated from approximately 21.000 y 14C BP. This lagoon is located in northeast Brazilian coast in a region with a severe influenced from the Inter Tropical Convergence Zone (ITCZ), representing a hotspot area for paleoenvironmental studies. Eleven phenols were quantified in cores samples, samples from possible sources as plants and soils and superficial sediments. The results were compared with secondary data from mineralogy, pollen and diatoms from the same cores to verified the applicability of the lignin phenols data as a potential tracer of paleoenvironmental events. The lagoon water level oscillation was tested through the λ values variation. High λ values recorded in the shoreline zone were related to macrophytes organic matter sedimentation. Among the phenols compounds analyzed high amounts of siringaldehyde (Sl) from S group were related to the aquatic plants typical from swamp environment and marking the beginning of the lacustrine sedimentation. The feluric acid (Fd) compound from C group trace the predominance of macrophytes in the shoreline zone while the p-hidroxybenzaldehyde (pBl) highlight as a periphyton tracer. The presence of these compounds in different concentrations characterized alternate in the aquatic communities composition and biomass been related with climatologic events. Moist conditions period influenced runoff events that indirect increase the water level turning the shoreline zone in a high productivity zone attested by high lignin values. These lignin results were in more agreement with diatoms results than pollen data. Finally, the organic matter composition of the sedimentary profile situated in the shoreline suggests the following ecological succession: (I) dunes; (II) swamp (III) lagoon shore with macrophytes; (IV) lagoon offshore.

Les invasions biologiques sont considérées comme étant une cause majeure de changement des écosystèmes. Les impacts écologiques des espèces invasives pourraient être modulés par la variabilité intraspécifique des traits biologiques et écologiques entre et au sein de leurs populations. Cette thèse a révélé, à différentes échelles spatiales, la présence de variabilités phénotypiques fortes chez deux espèces invasives, Lepomis gibbosus et Procambarus clarkii. Il est apparu que les réponses phénotypiques des individus aux conditions environnementales pourraient être complexes, révélant notamment la contre productivité des méthodes de gestion utilisées pour contrôler les populations invasives et l'importance de l'histoire de colonisation des populations dans les relations phénotype-environnement. Des expérimentations ont également démontré comment la variabilité intraspécifique pourrait moduler les effets des espèces invasives sur la structure des communautés et le fonctionnement des écosystèmes. Ces résultats soutiennent l'idée qu'intégrer la variabilité intraspécifique dans un contexte d'invasion biologique est indispensable afin de mieux évaluer les impacts et adapter les méthodes de gestion aux caractéristiques des populations invasifs. / While biological invasions are widely recognized as a major cause of ecosystem changes, the ecological impacts of invasive species could be modulated by intraspecific variability in ecological traits occurring between and within populations. The present work demonstrated, at different geographical scales, the existence of a strong phenotypic variability within two freshwater invaders, Lepomis gibbosus and Procambarus clarkii. In addition, phenotypic responses to environmental conditions was demonstrated to be complex, revealing notably that the methods used to control invasive populations can be counter-productive and that the colonization history of invasive populations is an important driver of phenotype-environment relationships. Experimental approaches also demonstrated that intraspecific variability modulated the intensity of the ecological impacts of invasive species on community structure and ecosystem functioning. These findings strongly support the idea that integrating intraspecific variability in the context of biological invasions is essential to better appreciate their impacts on recipient ecosystem and ultimately improve the efficient of management methods based on the characteristics of invasive populations

No description available.

The impact of natural disasters is often exacerbated by a disparity between resources for relief and recovery. When the barrio of Punta Santiago in Puerto Rico was devastated by Hurricane Maria in September of 2017, many of its residents lived in the remains of their homes for over a year while they rebuilt from wind damage and flood waters that rose over 6 feet. As climate change leads to an even more constrained timeline for response with increasingly frequent and intense storms, the future of Punta Santiago and other coastal communities worldwide will necessitate strategies ranging from nature-based shore protection systems, coastal setbacks, and managed retreat. This thesis investigates the time disparate processes of disaster relief, recovery, and climate adaptation through the lens of their impact upon the interdependent identities of people and place as informed by theorists and designers including J.B. Jackson and Patrick Geddes. My approach works from the scale of the Antón Ruíz watershed to the delta to uncover the historical and contemporary processes that knit people in the region to the land. I identify commonalities in the immediate recovery needs and long-term resiliency of the community and ecosystems, and seek to support ongoing globally significant research of the rare coastal systems surrounding Punta Santiago. The proposed design, a causeway linking the coast to the hills, dovetails disaster relief and recovery with climate adaptation by providing a persistent connection that restores and reveals the dynamic coastal landscape. / Master of Landscape Architecture / Global warming is correlated with an increase in sea level rise, atmospheric moisture (water content in the air), and surface sea temperatures. The body of research around the complex interaction of these factors is growing, but current projections are that warmer seas will cause more intense hurricanes. Coastal communities, particularly those with fewer economic resources, bear the brunt of this trend and recovery is more difficult with each passing storm. After Hurricane Maria struck in September 2017, many residents of the barrio of Punta Santiago in Puerto Rico lived in the remains of their homes for over a year with little resources to rebuild from the severe wind damage and flood waters that rose over 6 feet. Recovery is still underway almost two years later. A sustainable way forward for Punta Santiago and other coastal communities worldwide necessitates strategies ranging from natural shore stabilization techniques like mangrove buffers and living reefs to restrictions on coastal development, and even the relocation of communities. This thesis investigates the time disparate processes of disaster relief, recovery, and climate adaptation through the lens of their impact upon the interdependent identities of people and place as informed by theorists and designers including J.B. Jackson and Patrick Geddes. My approach works from the scale of the Antón Ruíz watershed to the delta to uncover the historical and contemporary land use that knit people in the region to the land. I identify commonalities in the immediate recovery needs and long-term resiliency of the community and ecosystems, and seek to support ongoing globally significant research of the rare coastal systems surrounding Punta Santiago. The proposed design, a causeway linking the coast to the hills, dovetails disaster relief and recovery with climate adaptation by providing a persistent connection that restores and reveals the dynamic coastal landscape.