The extensive clearing and modification of natural systems from anthropogenic activities is a pressing global concern. Forest habitats and animal communities within forests are among the most highly impacted, globally. Forest destruction has been repeatedly documented as a driver of biodiversity loss. However, little is known about how animal communities respond when altered landscapes are abandoned and left to regenerate into secondary forests. It is thought that the regrowth of secondary forests may help reverse biodiversity loss by restoring habitats to similar conditions as prior to land conversion. Of the forest cover that remains, over half is secondary forest, and in many countries secondary forest cover has been steadily increasing. Therefore, it is important to understand how and if faunal communities recover during secondary forest regeneration. I combined meta-analytic, field-survey-based, and lab-based experimental techniques to determine how amphibians and reptiles respond to habitat change in general, and secondary forest regeneration on landscapes previously cleared for use as pasture. I addressed five specific questions: 1) what are the effects of habitat alteration on amphibians and reptiles?, 2) what are the effects of secondary forest succession on amphibians and reptiles?, 3) what is the relative importance of stochastic and deterministic effects on community assembly during secondary forest succession?, 4) how do amphibian and reptile species composition, probability of occurrence, and species richness change over the course of secondary forest succession?, and 5) is thermal quality of habitat an important mechanism of species response to secondary forest succession? I found that secondary forest has high conservation value for many amphibian and reptile species, environmental changes associated with secondary forest succession have a significant effect on shaping amphibian and reptile community composition, thermal quality is an important mechanism for species response and that strength of response is mediated by species-specific thermal biology. I also highlight the importance of riparian corridors in maintaining species diversity in modified habitats.

Exotic invasive plant species can alter aquatic habitats potentially influencing the macroinvertebrate community and foraging fishes. Therefore, I investigated the hypothesis that Hydrilla verticillata will alter habitat important to macroinvertebrate community structure and bluegill foraging efficiency. Studies were conducted in ponds and aquaria. At the pond level, macroinvertebrate abundance, richness, and biomass in a hydrilla-dominated habitat did not differ significantly from a diverse plant habitat. Indicator taxa did differ significantly between respective treatments. The data suggest hydrilla beds may not provide increased macroinvertebrate abundance and richness compared to diverse plant beds as previously thought. In aquaria, habitat complexity (Ihv) and light transmittance were influenced by increasing the homogeneity of hydrilla in an aquatic bed habitat. In addition, bluegill foraging efficiency was affected negatively by increasing spatial complexity of a hydrilla dominated habitat. Therefore, a shift to a monotypic hydrilla habitat can alter macroinvertebrate community composition and impact bluegill foraging success.

The effects of small-scale shoreline residential development on littoral fish abundance and species richness was examined at three different scales of observation (within 122, 244, and 488 meters) in Lake Simcoe (Ontario, Canada). A mixed model regression was used to test for effects of development after accounting for seasonal and spatial variation in environmental variables known to affect distribution and abundance of fish. Fish were aggregated near single development structures, such as permanent docks, and repelled from other single structures, such as bank stabilisation. Shoreline developed with multiple features, such as docks combined with break walls, tended to be positively correlated with fish abundance but negatively correlated with species richness. Features such as docks and break walls combined with boathouses were generally associated with a decrease in both abundance and richness. Cluster analysis detected no consistent pattern of association between specific fish assemblages and residential development across the three scales of observation. Increased density and diversity of shoreline residential development tended to be associated with reduced fish abundance and species richness. The specific development features associated with these patterns change with the scale of observation, indicating that fish responded to proximally and distantly located habitat alterations.

Globally urbanisation impacts on 88% of amphibian species and is recognised as a major cause for the observed amphibian declines. This is as result of habitat fragmentation, alteration in habitat morphology and degradation of habitat quality. The interference of anthropogenic noise on anuran communication and the impacts thereof on their breeding success has become a major research focus in recent conservation studies. . However, within the African continent very little research has been conducted on the effects of urbanisation on anuran habitat and the acoustic environment, which is the main focus of this study. The thesis is structured as follows: CHAPTER ONE provides an introduction to the field of urban ecology and relates it to amphibian conservation. The chapter reviews the far reaching and diverse effects of urbanisation on frog populations reported in literature across the world and also supply a broad introduction to the succeeding chapters. It also briefly summarises evidence from literature on the positive contributions brought about by the developed world. Following the vast negative impacts of urbanisation, the importance of amphibians is briefly discussed to motivate their conservation in urban environments, before concluding with a motivation for the need for urban ecological research on amphibians in South Africa. CHAPTER TWO addresses the distribution of amphibian communities across an urban-rural gradient in the city of Potchefstroom and assesses the habitat determinants explaining distribution at both local (pond) and landscape scales. Four surveys conducted spanned the breeding seasons of all species occurring in this region and included three different sampling techniques to detect fish and anuran larvae species. Seven micro-habitat and seven landscape variables were included to evaluate determinants of habitat use among local species and species richness. Using Bayesian modelling, aquatic vegetation, predatory fish and pond size was found to be major determinants shaping species richness on a local scale, whereas surface area of urban central business district had only a slightly negative correlation with species richness on a landscape scale. This is a pioneer study for documenting effects of urbanisation on amphibian communities along an urban-rural gradient in Africa. CHAPTER THREE evaluates the extent of the influence of aircraft acoustic noise on the calling behaviour of the critically endangered Pickersgill’s Reed Frog, Hyperolius pickersgilli. Literature documenting the effects of airplane noise on anuran calling activity is very limited and this study aimed not only to contribute to existing knowledge, but also to provide the first study of its kind within South Africa. Effects on five call properties of H. pickersgilli were determined using passive and directional recording equipment at two sites, reflecting presence and absence of aircraft flybys. Results showed an increase in calling rate of H. pickersgilli during aircraft flybys. Hyperolius pickersgilli was found to call throughout the night until just before sunrise. The calling behaviour, frequency structure and call sound pressure level of H. pickersgilli suggest that this species is prone to be effected by continuous anthropogenic noise. However, the lack of flights between midnight and sunrise provides a period of no disturbance for the frogs. Future studies on the effects of change in calling behaviour should be supported by playback studies at quiet sites and connected to breeding success to determine if these effects are detrimental to the survival of this critically endangered species. CHAPTER FOUR focussed on the Western Leopard Toad, Amietophrynus pantherinus and was divided into two major parts. One component focussed on the migration of this species across roads and aimed to firstly quantify the number of individuals migrating over a 500 m stretch of road using a drift fence system operated by public volunteers. The drift fence proved very successful, with no roadkill observed during the time it was in place. This study also stressed that large numbers of toads (average of 20.47% of 2 384 toads over six breeding seasons) are still being killed on the urban and suburban roads. Road patrol statistics collected by volunteers are biased in the sense that it is prone to human error, but when a drift fence is constructed, bias is excluded and space for human error limited. The study also provided road sensitivity areas analysed using geographic information systems to create digital buffer zones of 250 m, 500 m and 1 000 m around selected breeding sites. Secondly the study aimed to evaluate the use of data collected by these citizens occupying a volunteering role in the toad’s conservation. The second part of this study was directed towards the acoustic analysis of the call of A. pantherinus. The two main objectives of this component were to 1) evaluate the extent of variation of the call properties in order to 2) assess whether the ambient anthropogenic noise have an effect on these properties. Seven call properties for advertisement calls and four for release calls were analysed. Call properties were found to vary significantly between populations (P<0.05). Although sound pressure level was found to have an effect on variation by using canonical redundancy analysis, variation can also be explained by the geographical isolation of the populations. CHAPTER FIVE provided novel data on the extensive repertoire of Amietia quecketti in terms of its unique calling behaviour. Directional recordings were used to examine the extent of the variation in the two-part call (click-note followed by a whine-note). The whine-note was re-described and four different notes were designated, including the tonal-note, creak-note, pulsatile- / rip-note, and whine-note. Furthermore, the newly assigned whine-note was divided into nine phases that differed in frequency structure. Also, evidence is provided that A. quecketti males call at high frequencies. The success of A. quecketti in urban environments as observed in Chapter 2 is described in terms of this species’ extensive repertoire and unusual frequency structure. CHAPTER SIX provides insight into the effects of atmospheric conditions on the calling behaviour of Amietia quecketti, giving the proximate impact urbanisation has on weather conditions as well as the potential impact human activities can have on climate change on the long term. Calling activity was monitored over a nine-week period together with data from a mobile weather station which logged atmospheric variables every five minutes. Amietia quecketti was found to call most intensely between 00h00 and 03h00 in the morning and was most active in May, June and August. Humidity, temperature and wind velocity were found to have significant effects (P<0.05) on the calling activity of A. quecketti. CHAPTER SEVEN is concerned with the attitudes of people towards frogs in South Africa. The first part of this study assessed the attitudes of people towards frogs in Potchefstroom. Surveys were distributed via the internet as well as manually to reach people with no internet access as well. Attitudes of people of Potchefstroom were mostly positive with more than half of the sampled population of 295 respondents indicating a strong liking in frogs. This study provides evidence that the presence of myths and knowledge can highly affects people’s attitudes towards frogs. The second part of this study focussed on the motivations of volunteers saving Western Leopard Toads from roadkill in Cape Town, South Africa. Volunteers were motivated by a strong value-driven approach to saving toads. CHAPTER EIGHT provides a general discussion and outline on the contributions this study presented and also the new areas where more research is needed within the extent of the field of urban ecology from a South African perspective. / hD (Zoology), North-West University, Potchefstroom Campus, 2014

Globally urbanisation impacts on 88% of amphibian species and is recognised as a major cause for the observed amphibian declines. This is as result of habitat fragmentation, alteration in habitat morphology and degradation of habitat quality. The interference of anthropogenic noise on anuran communication and the impacts thereof on their breeding success has become a major research focus in recent conservation studies. . However, within the African continent very little research has been conducted on the effects of urbanisation on anuran habitat and the acoustic environment, which is the main focus of this study. The thesis is structured as follows: CHAPTER ONE provides an introduction to the field of urban ecology and relates it to amphibian conservation. The chapter reviews the far reaching and diverse effects of urbanisation on frog populations reported in literature across the world and also supply a broad introduction to the succeeding chapters. It also briefly summarises evidence from literature on the positive contributions brought about by the developed world. Following the vast negative impacts of urbanisation, the importance of amphibians is briefly discussed to motivate their conservation in urban environments, before concluding with a motivation for the need for urban ecological research on amphibians in South Africa. CHAPTER TWO addresses the distribution of amphibian communities across an urban-rural gradient in the city of Potchefstroom and assesses the habitat determinants explaining distribution at both local (pond) and landscape scales. Four surveys conducted spanned the breeding seasons of all species occurring in this region and included three different sampling techniques to detect fish and anuran larvae species. Seven micro-habitat and seven landscape variables were included to evaluate determinants of habitat use among local species and species richness. Using Bayesian modelling, aquatic vegetation, predatory fish and pond size was found to be major determinants shaping species richness on a local scale, whereas surface area of urban central business district had only a slightly negative correlation with species richness on a landscape scale. This is a pioneer study for documenting effects of urbanisation on amphibian communities along an urban-rural gradient in Africa. CHAPTER THREE evaluates the extent of the influence of aircraft acoustic noise on the calling behaviour of the critically endangered Pickersgill’s Reed Frog, Hyperolius pickersgilli. Literature documenting the effects of airplane noise on anuran calling activity is very limited and this study aimed not only to contribute to existing knowledge, but also to provide the first study of its kind within South Africa. Effects on five call properties of H. pickersgilli were determined using passive and directional recording equipment at two sites, reflecting presence and absence of aircraft flybys. Results showed an increase in calling rate of H. pickersgilli during aircraft flybys. Hyperolius pickersgilli was found to call throughout the night until just before sunrise. The calling behaviour, frequency structure and call sound pressure level of H. pickersgilli suggest that this species is prone to be effected by continuous anthropogenic noise. However, the lack of flights between midnight and sunrise provides a period of no disturbance for the frogs. Future studies on the effects of change in calling behaviour should be supported by playback studies at quiet sites and connected to breeding success to determine if these effects are detrimental to the survival of this critically endangered species. CHAPTER FOUR focussed on the Western Leopard Toad, Amietophrynus pantherinus and was divided into two major parts. One component focussed on the migration of this species across roads and aimed to firstly quantify the number of individuals migrating over a 500 m stretch of road using a drift fence system operated by public volunteers. The drift fence proved very successful, with no roadkill observed during the time it was in place. This study also stressed that large numbers of toads (average of 20.47% of 2 384 toads over six breeding seasons) are still being killed on the urban and suburban roads. Road patrol statistics collected by volunteers are biased in the sense that it is prone to human error, but when a drift fence is constructed, bias is excluded and space for human error limited. The study also provided road sensitivity areas analysed using geographic information systems to create digital buffer zones of 250 m, 500 m and 1 000 m around selected breeding sites. Secondly the study aimed to evaluate the use of data collected by these citizens occupying a volunteering role in the toad’s conservation. The second part of this study was directed towards the acoustic analysis of the call of A. pantherinus. The two main objectives of this component were to 1) evaluate the extent of variation of the call properties in order to 2) assess whether the ambient anthropogenic noise have an effect on these properties. Seven call properties for advertisement calls and four for release calls were analysed. Call properties were found to vary significantly between populations (P<0.05). Although sound pressure level was found to have an effect on variation by using canonical redundancy analysis, variation can also be explained by the geographical isolation of the populations. CHAPTER FIVE provided novel data on the extensive repertoire of Amietia quecketti in terms of its unique calling behaviour. Directional recordings were used to examine the extent of the variation in the two-part call (click-note followed by a whine-note). The whine-note was re-described and four different notes were designated, including the tonal-note, creak-note, pulsatile- / rip-note, and whine-note. Furthermore, the newly assigned whine-note was divided into nine phases that differed in frequency structure. Also, evidence is provided that A. quecketti males call at high frequencies. The success of A. quecketti in urban environments as observed in Chapter 2 is described in terms of this species’ extensive repertoire and unusual frequency structure. CHAPTER SIX provides insight into the effects of atmospheric conditions on the calling behaviour of Amietia quecketti, giving the proximate impact urbanisation has on weather conditions as well as the potential impact human activities can have on climate change on the long term. Calling activity was monitored over a nine-week period together with data from a mobile weather station which logged atmospheric variables every five minutes. Amietia quecketti was found to call most intensely between 00h00 and 03h00 in the morning and was most active in May, June and August. Humidity, temperature and wind velocity were found to have significant effects (P<0.05) on the calling activity of A. quecketti. CHAPTER SEVEN is concerned with the attitudes of people towards frogs in South Africa. The first part of this study assessed the attitudes of people towards frogs in Potchefstroom. Surveys were distributed via the internet as well as manually to reach people with no internet access as well. Attitudes of people of Potchefstroom were mostly positive with more than half of the sampled population of 295 respondents indicating a strong liking in frogs. This study provides evidence that the presence of myths and knowledge can highly affects people’s attitudes towards frogs. The second part of this study focussed on the motivations of volunteers saving Western Leopard Toads from roadkill in Cape Town, South Africa. Volunteers were motivated by a strong value-driven approach to saving toads. CHAPTER EIGHT provides a general discussion and outline on the contributions this study presented and also the new areas where more research is needed within the extent of the field of urban ecology from a South African perspective. / hD (Zoology), North-West University, Potchefstroom Campus, 2014

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2017-05-17T11:08:27Z No. of bitstreams: 2 Tese - Lorena Dall´Ara Guimarães - 2006.pdf: 2423703 bytes, checksum: 83bf4f4172b792982caccc6cf3c41ff2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-05-17T11:48:10Z (GMT) No. of bitstreams: 2 Tese - Lorena Dall´Ara Guimarães - 2006.pdf: 2423703 bytes, checksum: 83bf4f4172b792982caccc6cf3c41ff2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-05-17T11:48:10Z (GMT). No. of bitstreams: 2 Tese - Lorena Dall´Ara Guimarães - 2006.pdf: 2423703 bytes, checksum: 83bf4f4172b792982caccc6cf3c41ff2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2006-02-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This study aimed to examine patterns of anuran species richness in twenty municipalities in the State of Goiás, central Brazil. We also compared richness of anuran species among these localities and verified the patterns of spatial distribution for four habitat types (gallery forests, ponds associated to gallery forest, ponds associated to cerrado sensu stricto, and ponds close to anthropic area). Surveys were conducted between 2001 and 2005. Considering the four habitat types, a total of 6,491 individuals from 52 anuran species were registered. Calling males were found on the ground, shrubs, and grasses. Ponds associated to cerrado sensu stricto showed the highest species richness. In contrast, gallery forest assemblages exhibited the highest species diversity and equitability. The largest number of individuals was found in disturbed areas and ponds associated to cerrado sensu stricto. Similarity analysis showed that open habitats had the most similar communities, while the most dissimilar assemblages were observed between gallery forests and ponds within disturbed areas. Seven species in the families Leptodactylidae and Hylidae showed significant indicative values (bioindicators) for particular habitats. A total of 61 species was registered in twenty municipalities, representing 44.7% of the anuran richness registered for the Cerrado. The highest species richness was found in the municipality of Silvânia, while the lowest richness was registered in Mundo Novo. The results showed a non-significant correlation between socio-economics variables and anuran species composition. Anuran species richness seems to be lower close to areas used for the establishment of pastures and agriculture. On the other hand, species richness tends to be higher (likely through succession) in areas without human disturbance. Results of this study could or should be considered during development of management strategies focusing on amphibian conservation in the Cerrado biome. Moreover, a better understanding of how different fragmentation degrees affect amphibian diversity is important to access the influence of habitat quality on Cerrado´s amphibians, and also to improve management programs focused on amphibian conservation. / Este estudo objetivou examinar os padrões de riqueza de espécies de anfíbios anuros em 20 municípios do estado de Goiás, no Brasil Central, como também comparar a diversidade e riqueza de espécies de anuros, e verificar os padrões de distribuição espacial em quatro tipos de habitats (floresta de galeria, brejo associado à floresta de galeria, brejo associado a cerrado sensu stricto e brejo situado em área antropizada) As coletas foram feitas entre 2001 e 2005. Em relação aos quatro tipos de habitats, um total de 6.491 indivíduos de 52 espécies foram registradas. Machos vocalizantes foram principalmente encontrados no chão, arbustos e gramíneas. Brejos associados a cerrado sensu stricto apresentaram a maior riqueza de espécies. Ao contrário, florestas de galeria apresentaram os maiores valores para diversidade e equitabilidade. O maior número de indivíduos foi encontrado em áreas antropizadas e brejos associados a cerrado sensu stricto. O índice de similaridade de Bray-Curtis mostrou que os habitats de áreas abertas têm comunidades mais similares, enquanto as comunidades mais dissimilares foram àquelas encontradas em florestas de galeria e aquelas situadas em áreas antropizadas. Sete espécies das famílias Leptodactylidae e Hylidae apresentaram valores indicativos significantes (bioindicadores) de habitats particulares. Um total de 61 espécies foi registrado nos vinte municípios, o que representa 43,26% da riqueza de espécies de anfíbios encontrados no Cerrado. O maior número de espécies foi registrado no município de Silvânia, leste do estado e o menor em Mundo Novo, noroeste goiano. Os resultados mostraram uma correlação não significativa entre as variáveis sócio-econômicas e a composição de espécies de anfíbios. A riqueza de espécies de anfíbios parece sofrer influência pelas áreas usadas para o estabelecimento de pastagens e agricultura. Por outro lado, a riqueza tende ser mais alta (provavelmente por sucessão) em áreas sem fatores antropogênicos. Os resultados desse estudo podem ser considerados para o desenvolvimento de estratégias de manejo, com enfoque na conservação de anfíbios das paisagens do Cerrado. Além disso, o conhecimento da influência dos diferentes graus de fragmentação dos habitas naturais na diversidade de anfíbios, é importante para o entendimento do funcionamento das comunidades dos anfíbios do Cerrado, e conseqüentemente, para o melhoramento no que diz respeito ao manejo e conservação dessa fauna.

Tesis por compendio / [ES] El agua constituye un recurso esencial cuya disponibilidad limitada y su creciente demanda hace que sea considerado como un elemento de gran valor desde diversos puntos de vista (ambiental, biológico, social, económico, etc.). El mantenimiento de condiciones favorables que permitan un equilibrio medioambiental adecuado es una de las metas de una adecuada planificación y gestión de recursos hídricos. Una de las acciones principales para la preservación de la biodiversidad de las cuencas consiste en la implementación de caudales ecológicos. Para ello, es importante poder contar con herramientas adecuadas que permitan cuantificar los efectos de los cauda-les ecológicos sobre las actividades socioeconómicas y el medio ambiental. Esta tesis tiene como objetivo proponer metodologías para la obtención y análisis de indicadores que permitan la optimización de regímenes de caudales ecológicos en sistemas de recursos hídricos complejos. Estas metodologías posibilitan evaluar los efectos de los caudales ecológicos en la alteración hidrológica, la alteración del hábitat, las garantías de las demandas, y la explotación del recurso hídrico. Esta tesis doctoral se estructura como un compendio de tres artículos científicos publicados en revistas del primer y segundo cuartil del Journal Citation Reports. En el primer artículo se define una metodología para el análisis de la alteración hidrológica en sistemas altamente regulados para diferentes escenarios de caudales ecológicos, apoyada en la utilización de modelos de simulación de la gestión de sistemas de recursos hídricos, y la posterior estimación y agrupación de indicadores de alteración hidrológica. Dicha metodología ha sido aplicada en la parte española de la Demarcación Hidrográfica del Duero. El segundo artículo plantea una metodología para la obtención de un indicador de alteración del hábitat en cuencas reguladas, mediante la aplicación conjunta de un modelo de simulación de la gestión de cuencas y un modelo de estimación de series temporales de hábitat de las especies acuáticas presentes en la zona de estudio. La metodología se aplica en el sistema de explotación del Órbigo, perteneciente a la Demarcación Hidrográfica del Duero. Las series temporales de hábitat fueron obtenidas y analizadas para diferentes escenarios de regímenes de caudales ecológicos, evaluando sus efectos en la alteración del hábitat y las garantías de las demandas. El tercer artículo propone una metodología para evaluar la variación temporal y espacial del índice de explotación del recurso hídrico (WEI+) en cuencas reguladas. Esta metodología, que fue aplicada en la cuenca del río del Órbigo, permite analizar los efectos de los regímenes de caudales eco-lógicos en el estrés hídrico de los distintos tramos de rio de una cuenca regulada. El enfoque propuesto para reducir la escala espacial del índice de explotación del recurso hídrico es también es útil para identificar las mejores fuentes de agua en las cuencas fluviales para satisfacer futuras demandas de agua y/o restricciones ambientales. Finalmente, a partir de la información obtenida de estas metodologías, se realiza un análisis conjunto de todos estos parámetros para las diferentes alternativas de caudal ecológicos planteadas. Para ello, se evalúan de manera conjunta indicadores globales de alteración hidrológica, alteración de hábitat, déficits de las demandas y estrés hídrico. Estos indicadores globales facilitan, tanto a los gestores como a los usuarios del agua, el análisis de estrategias de planificación y gestión de recursos hídricos. / [CA] L'aigua constitueix un recurs essencial la disponibilitat limitada del qual i la seua creixent demanda fa que siga considerat com un element de gran valor des de diversos punts de vista (ambiental, biològic, social, econòmic, etc.). El manteniment de condicions favorables que permeten un equilibri mediambiental adequat és una de les metes d'una adequada planificació i gestió de recursos hídrics. Una de les accions principals per a la preservació de la biodiversitat de les conques consisteix en la implementació de cabals ecològics. Per a això, és important poder comptar amb eines adequades que permeten quantificar els efectes dels cabals ecològics sobre les activitats socioeconòmiques i el mitjà ambiental. Aquesta tesi té com a objectiu proposar metodologies per a l'obtenció i anàlisi d'indicadors que permeten l'optimització de règims de cabals ecològics en sistemes de recursos hídrics complexos. Aquestes metodologies possibiliten avaluar els efectes dels cabals ecològics en l'alteració hidrològica, l'alteració de l'hàbitat, les garanties de les demandes, i l'explotació del recurs hídric. Aquesta tesi doctoral s'estructura com un compendi de tres articles científics publicats en revistes del primer i segon quartil del Journal Citation Reports. En el primer article es defineix una metodologia per a l'anàlisi de l'alteració hidrològica en sistemes altament regulats per a diferents escenaris de cabals ecològics, recolzada en la utilització de models de simulació de la gestió de sistemes de recursos hídrics, i la posterior estimació i agrupació d'indicadors d'alteració hidrològica. Aquesta metodologia ha sigut aplicada en la part espanyola de la Demarcació Hidrogràfica del Duero. El segon article planteja una metodologia per a l'obtenció d'un indicador d'alteració de l'hàbitat en conques regulades, mitjançant l'aplicació conjunta d'un model de simulació de la gestió de conques i un model d'estimació de sèries temporals d'hàbitat de les espècies aquàtiques presents en la zona d'estudi. La metodologia s'aplica en el sistema d'explotació del Órbigo, pertanyent a la Demarcació Hidrogràfica del Duero. Les sèries temporals d'hàbitat van ser obtingudes i analitzades per a diferents escenaris de règims de cabals ecològics, avaluant els seus efectes en l'alteració de l'hàbitat i les garanties de les demandes. El tercer article proposa una metodologia per a avaluar la variació temporal i espacial de l'índex d'explotació del recurs hídric (WEI+) en conques regulades. Aquesta metodologia, que va ser aplicada en la conca del riu del Órbigo, permet analitzar els efectes dels règims de cabals ecològics en l'estrés hídric dels diferents trams de va riure d'una conca regulada. L'enfocament proposat per a reduir l'escala espacial de l'índex d'explotació del recurs hídric és també és útil per a identificar les millors fonts d'aigua en les conques fluvials per a satisfer futures demandes d'aigua i/o restriccions ambientals. Finalment, a partir de la informació obtinguda d'aquestes metodologies, es realitza una anàlisi conjunta de tots aquests paràmetres per a les diferents alternatives de cabal ecològics plantejades. Per a això, s'avaluen de manera conjunta indicadors globals d'alteració hidrològica, alteració d'hàbitat, dèficits de les demandes i estrés hídric. Aquests indicadors globals faciliten, tant als gestors com als usuaris de l'aigua, l'anàlisi d'estratègies de planificació i gestió de recursos hídrics. / [EN] Water is an essential resource whose limited availability and growing demand means that it is considered an element of great value from various points of view (environmental, biological, social, economic, etc.). The maintenance of favourable conditions that allow an adequate environmental balance is one of the goals of water resources planning and management. One of the main actions for the preservation of the basin biodiversity in the implementation of environmental flows. To this end, it is important to have adequate tools that allow assessing the effects of environmental flows on socioeconomic activities and the environment. This thesis aims to propose methodologies for assessing and analysing indicators that allow the optimization of ecological flow regimes in complex water resource systems. These methodologies enable evaluating the effects of ecological flows on hydrological alteration, habitat alteration, reliability of water demands, and water resources exploitation. This doctoral thesis is structured as a compendium of three research papers published in journals indexed in the first and second quartiles of the Journal Citation Reports. In the first paper, a methodology for the analysis of hydrological alteration in highly regulated systems for different scenarios of ecological flows is pro-posed. The methodology is endorsed using models for the management of water resource systems, and the subsequent computation and grouping of indicators of hydrological alteration. This methodology was applied to the Spanish part of the Duero Water District. The second paper proposes a methodology for assessing an indicator of habitat alteration in regulated basins through the joint application of a basin management simulation model and a model to estimate habitat time series of the aquatic species present in the study zone. The methodology is applied to the Órbigo exploitation system, which belongs to the Duero Water District. Habitat time series were obtained and analysed for different environmental flow regime scenario, and the effects of this environmental flows on habitat alteration and water demand reliability were assessed. The third paper proposes a methodology to evaluate the temporal and spatial variation of the water exploitation index (WEI+) in regulated basins. This methodology, which was applied in the Órbigo river basin, allows ana-lysing the effects of ecological flow regimes on water stress in the different river sections of a regulated basin. The proposed approach to reduce the spatial scale of the water exploitation index is also helpful to identify the best water sources in river basins to meet future water demands and/or higher values of environmental restrictions. Finally, based on the information obtained through the application of these methodologies, a joint analysis of all these parameters was carried out for the different proposed environmental flow alternatives. To this end, global indicators of hydrological alteration, habitat alteration, water demand deficits and water stress are jointly evaluated. These global indicators help water managers and users to analyse strategies of water resources planning and management. / The authors thank the Spanish Ministry of Science and Innovation (MCIN) and Spanish Research Agency (AEI) for the financial support MCIN/AEI/10.13039/501100011033 to RESPHIRA project (PID2019- 106322RB-I00). RB was partly funded by MCIN/AEI /10.13039/501100011033 through Juan de la Cierva program (IJC2019-038848-I). Funding for open ac- cess charge: CRUE-Universitat Politècnica de València. The authors also thank three anonymous reviewers for their suggestions to improve this work. / Pardo Loaiza, J. (2023). Mejora de la gestión del recurso hídrico mediante la incorporación de indicadores de regímenes ecológicos en el análisis de sistemas de recursos hídricos [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/192461 / Compendio