The pelagic zone of lakes is defined as the water column over the area of the lake benthos that does not receive enough light from the sun to allow macrophytes to grow. The four chapters of this thesis explore the spatial ecology of predator-prey interactions between schooling fish and their fish predators in this featureless environment. We first developed novel hydroacoustics methods to study fish and fish school swimming behaviour in the pelagic zone (Chapter 1 and 2). Then we characterized our in-situ school formation and prey movement observations using an ideal gas model to better understand the mechanisms that lead to fish and school densities during the daytime (Chapter 2 and 3). With this model we estimated the functional relationship between the schooling prey densities and predator encounter rates, and verified with empirical data a counterintuitive relationship that encounter rates decreased as overall prey densities increased (Chapter 3). The encounter rates suggested that predation within the pelagic zone might be greatly influenced by external forces if they provide spatial structure which encourages greater degrees of prey aggregation in predictable locations. In this regard we examined the predator-prey dynamics under wind and found large redistributions of prey and predators under windy conditions leading to greater aggregations in downwind locations. Further, we found that our study fish were larger in lakes that were oriented into the wind, perhaps demonstrating a benefit to fish growth under windy conditions (Chapter 4).

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 112-134).

Thesis (M.A.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains ix, 121 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 117-121).

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 188-212).

Thesis (Ph. D.)--Duke University, 2008. / Includes bibliographical references.

Thesis (M.A.)--The University of North Carolina at Greensboro, 2008. / Directed by Roy Stine; submitted to the Dept. of Geography. Title from PDF t.p. (viewed Apr. 13, 2010). Includes bibliographical references (p. 58-64).

Orientador: Denise de Cerqueira Rossa-Feres / Coorientador: Carlos Eduardo Conte / Banca: Paulo de Marco Jr / Banca: Mauricio Osvaldo Moura / Banca: Vitor Hugo Mendonça do Prado / Banca: Fernando Rodrigues Silva / Resumo: Com intuito de compreender os processos que determinam a composição e distribuição da diversidade de anfíbios em paisagens subtropicais, nós (1) inventariamos a composição dos anfíbios em áreas de campos naturais entremeados a formações florestais da Mata Atlântica, (2) avaliamos como características da paisagem (i.e., cobertura e uso do solo) e dos habitats (i.e., área, hidroperíodo, cobertura de dossel dos corpos d'água) influenciam os padrões de distribuição da diversidade taxonômica e filogenética e (3) avaliamos quais e como gradientes ambientais e espaciais influenciam a estrutura filogenética da metacomunidade regional. Empregamos três métodos de amostragem (transecção, amostragem em sítio de reprodução e busca ativa) em 12 unidades de conservação e entorno, distribuídas nos Estados do Paraná e de Santa Catarina. As amostragens foram realizadas em diferentes períodos entre 2004 e 2014. Nós registramos 63 espécies de 11 famílias de anfíbios, das quais 20 espécies foram associadas aos campos, 19 às áreas florestais e ecótonos e 21 espécies foram generalistas. Espécies com um único indivíduo registrado não foram avaliadas quanto ao uso de habitat. Para avaliar a influência das características estruturais do habitat e da paisagem sobre os padrões de distribuição dos anfíbios, nós selecionamos oito das unidades de conservação e amostramos mensalmente, ao longo de um ano, entre oito e 14 corpos d'água em cada unidade, totalizando 81 corpos d'água (poças temporárias, lagoas... / Abstract: In order to understand wich processes determine the composition and distribution of amphibian diversity in subtropical landscapes, the goals of this work was (1) inventorying the composition of amphibians in areas of natural grasslands associated with Atlantic Forest, (2) assess how land coverage (i.e., land cover and use) and breeding habitats features (i.e., area, depth) influence the distribution patterns of taxonomic and phylogenetic diversity, (3) evaluate how environmental and spatial gradients influence the phylogenetic structure regional metacommunity. We employ three sampling methods (transect sampling, survey at breeding site and active search) in 12 conservation units, distributed in the states of Paraná and Santa Catarina. Samples were taken at different periods between 2004 and 2014. We recorded 63 species of amphibians distributed in 11 families. In relation to use of habitat by amphibians, 20 species were preferably associated with grasslands, 19 were preferably forest and forest edge, 21 generalist (recorded on forest, edge and grasslands environments). Species with a single individual recorded were not evaluated for their habitat use. In order to assess how land coverage and breeding habitats features influence the distribution patterns of taxonomic and phylogenetic diversity, we selected eight conservation units and sampled monthly, over a year, a minimum of 8 and a maximum of 14 water bodies in each unit, totaling 81 water bodies (i.e., pools, permanent ... / Doutor

Orientador: Lilian Casatti / Coorientador: Marcus V. Cianciaruso / Coorientador: Silvio F. B. Ferraz / Banca: Janne Soininen / Banca: Leandro Duarte / Banca: Rafael Leitão / Banca: Tadeu Siqueira / Resumo: Contexto. Em riachos neotropicais, poucos estudos têm considerado os efeitos de variáveis ambientais em diferentes escalas espaciais sobre a ictiofauna. Além disso, estudos relacionados com a escala em sua maioria incorporam uma única faceta e um único componente da biodiversidade, proporcionando uma visão incompleta da estrutura da comunidade de peixes. Objetivo. Determinar a contribuição relativa de características locais, de microbacia e dos padrões espaciais na explicação da variação dos componentes α e β das facetas taxonômica, funcional e filogenética de peixes de riachos. Métodos. Foram amostrados 85 trechos de riachos (= 85 microbacias) no Alto Rio Paraná, Brasil. Diversas análises estatísticas foram utilizadas para explicar as facetas e componentes da biodiversidade em função de variáveis locais, de microbacia e espaciais. Resultados. Para quase todas as facetas e seus componentes α e β, os fatores ambientais locais explicaram uma fração substancial da variância. As variáveis na escala de microbacia, de um modo inesperado, e a estruturação espacial, como esperado, contribuíram pouco para a variação da biodiversidade ou não foram significativas. Conclusões. Este estudo tem implicações claras para a proteção da biodiversidade íctica regional e poderiam ser integradas na gestão de riachos de diferentes maneiras. Primeiro, os resultados destacam a importância de fatores ambientais locais para a manutenção da biodiversidade de peixes de riachos situados em paisagens agrícolas. Por conseguinte, essas características ambientais chave devem ser restauradas ou, pelo menos, preservadas. Segundo, uma vez que funções e processos ecossistêmicos exercidos pela zona ripária foram ou estão sendo perdidas, ações voltadas para a restauração das matas ciliares na rede de drenagem devem ser uma prioridade nas bacias estudadas. Terceiro, já que as espécies raras que são funcionalmente e/ou... / Abstract: Context. In Neotropical streams, very few studies have considered the effects of environmental variables at different spatial scales on fish communities. Furthermore, scale-related studies mostly include only one facet and one component of biodiversity providing an incomplete picture of fish community structure. Objective. To determine the relative contributions of catchment and local environmental features and spatial patterns in explaining variation in the α- and β-components of taxonomic, functional and phylogenetic diversity facets of stream fish. Methods. Fish sampling was performed in 85 stream reaches (= 85 catchments) in the Alto Rio Paraná, Brazil. Different statistical analyzes were performed to explain the facets and components of biodiversity as a function of local, catchment or spatial variables. Results. For almost all facets and its α- and β-components, local environmental factors explained a substantial fraction of variance. Catchment variables, in an unexpected way, and spatial structuring, as expected, contributed little to the variation in the biodiversity or were not significant at all. Conclusions. This study has clear implications for protection of regional stream fish biodiversity and would be integrated into stream management in different ways. First, the results highlight the importance of local environmental factors for maintaining stream fish biodiversity in agricultural landscapes. Therefore, these key environmental features must be restored, or at least preserved. Second, because ecosystem functions and processes provided by riparian zone were or are being lost, actions directed toward restoring riparian forest in the drainage network should be a priority in the studied basins. Third, because rare species that are functionally and/or phylogenetically 'unique' possibly contributed disproportionately to the functional/phylogenetic dissimilarity among sites this group of species deserve special ... / Doutor

Social behavior and habitat selection of river otters (Lontra canadensis) are highly variable among populations and there is limited information on how space use of this mustelid changes in human-modified environments. Understanding the spatial ecology of river otters is important for efforts focused on habitat management and preventing human-wildlife conflicts. My objectives were to quantify: (1) home ranges and core areas, (2) second- and third-order habitat selection, and (3) relationships between home-range size and intensity of human development for river otters in southern Illinois. VHF transmitters were used to track river otters during 2014-2016. Home-range and core-area sizes then were compared between males (n = 8) and females (n = 10), as was home-range overlap. I also compared the frequency individuals were located <25 m from a conspecific between sexes. Habitat selection at the second and third orders was analyzed with an eigen-analysis of selection ratios. Male river otters had larger home ranges and core areas than females. Home ranges of males overlapped frequently; lack of core-area overlap among females suggested they may be territorial. Males also were located <25 m from a conspecific more frequently than females (P = 0.023), and male-male dyads shared space more than male-female and female-female dyads (P = 0.002). Herbaceous and wooded wetlands were most strongly selected for at both second- and third-order scales, but streams and ponds also were selected. Regarding terrestrial cover types, river otters selected land with vegetative cover over areas with impervious surface (e.g., parking lots and shopping centers). Forests were selected over crop fields at the third-order, but not second-order, scale. Use of urbanized land was uncommon for river otters, and there was a positive relationship (P = 0.004) between home-range size and the percentage of home range within developed open space (e.g., roads and residential lawns). The habitat selection and sociality of river otters in southern Illinois varied among individuals, as it does among river otter populations throughout North America. By recording sex differences in social behavior and selection of aquatic and upland habitat, my study provides wildlife biologists with a better understanding of river otter space use throughout a rural-urban gradient.

The decrease of biological diversity from low latitudes near the equator towards high latitudes is one of the most fundamental patterns noted in ecology. These trends have been the subject of numerous terrestrial and marine studies and have caused the proposal of several explanatory hypotheses. No single hypothesis has adequately accounted for these observed trends. Furthermore, large-scale patterns are frequently modified by processes acting at meso- to small-scales. It is imperative to understand the interaction of these processes to elucidate the mechanisms controlling the structure of intertidal assemblages. The main aim of this thesis was to test the influence of multiple processes at a range of spatial scales on biogenic engineers. Biogenic engineers, such as macroalgae, have been reported to be strongly influenced by processes such as grazing, biogeography and upwelling and subsequent effects are expected to be linked to their associated assemblages. I used infaunal assemblages associated with macroalgae as a model system to understand the interactive effects of meso-scale upwelling in conjunction with large-scale factors (regional and biogeographic). Three species of macroalgae, Hypnea spicifera, Champia lumbricalis and Bifurcaria brassicaeformis, inhabiting different but overlapping home ranges were used in this study. Smaller scale, physical attributes and the associated fauna of these algal species were compared. The effects of meso- to large-scale physical gradients on marine organisms have been investigated in many instances and resultant gradients in physical variables observed. This study was undertaken to investigate morphological trends exhibited by Hypnea spicifera and Champia lumbricalis to compare possible similarities between coastlines and to determine if inferred meso- to large-scale processes influence physical trends in a similar manner despite the coastlines being affected by different hydrodynamic processes. The macroalgae were located in two distinctly different upwelling regimes, Hypnea spicifera on the east and south coasts and Champia lumbricalis on the west coast. Upwelling (delivery of nutrients and primary production) was not found to be an important factor in determining the physical characteristics of macroalgae but there were clear patterns linked to latitude. Mean percentage cover of Hypnea spicifera was positively correlated with distance along the east and south coasts. Mean mass and mean surface area of H. spicifera were, however, negatively correlated with distance from Port St Johns. Mean frond length showed a negative trend but this relationship was not statistically significant. On the west coast, there was a significant increase in mean frond length from north to south for Champia lumbricalis. Mean surface area and mean mass of C. lumbricalis exhibited non-significant negative trends from north to south while there was a non-significant positive trend for mean percentage cover. Following the “Productivity Hypothesis”, these patterns from north to south along the coastlines of South Africa could have important implications for biodiversity associated with these algae. Many previous studies have focussed on the effects of upwelling on species (i.e. effects of nutrients and temperature) but have failed to separate this effect from large scale effects such as biogeography and latitudinal gradients. I tested the influence meso-scale upwelling, large-scale biogeographic processes and latitudinal gradients with two different species of macroalgae one on the east and south coasts of South Africa and the other on the west coast. Hypnea spicifera inhabits the east and south coasts of South Africa spanning two biogeographic provinces and is generally affected by relatively weak upwelling, whereas Champia lumbricalis inhabits the west coast spanning one biogeographic province which is subjected to intense persistent upwelling year round. Within the east and west coast biogeographic provinces there are, however, regions with both upwelling and non-upwelling. On the east and south coasts, entire assemblages differed significantly among the three Regions (St Lucia, Port Alfred and Knysna, while assemblages between upwelling/non-upwelling areas were not different. Assemblages on the different shores differed significantly from each other. There were no significant effects of region or upwelling for the number of individuals of Crustacea or Polychaeta, while Mollusca showed a significant effect of region. The number of individuals of other taxa showed a significant interaction of region and upwelling. Region had a significant effect on number of species of molluscs and other taxa, while there was no effect for either region or upwelling for the Crustacea or Polychaeta. In general different factors were shown to be important (region and shore) while upwelling was rarely important. On the west coast assemblages associated with C. lumbricalis were not influenced by region or upwelling but there were significant differences between shores. Region, upwelling ad shore did not affect number of individuals. There was a significant interaction of region and upwelling for the number of species of crustaceans, while numbers of species of Mollusca, Polychaeta and other taxa showed no effects. In general, regional factors strongly influenced most organisms, while upwelling played a minor role. Hypotheses about differences between upwelling and non-upwelling regions in terms of species abundances and composition due to the input of cold nutrient rich water were not supported. A link between the effects of larger-scale biogeographic factors and their influence on habitat forming taxa and the resultant effects on associated infauna would be a likely explanation for the patterns observed in this study. Diversity of assemblages is known to be influenced by the structural complexity of a habitat, increasing complexity increases the amount of available niches therefore potentially increasing the number of species found within that habitat. Three species of macroalgae, Hypnea spicifera, Champia lumbricalis and Bifurcaria brassicaeformis were selected on the basis of being structurally similar and having their distributional ranges overlap in order to elucidate the effects of structure and macroalgal species on associated assemblages. Hypnea spicifera is different in terms of surface area and biomass from Champia lumbricalis and Bifurcaria brassicaeformis. Assemblages of species found on the three rhodophytes showed both shore and the species of alga had significant effects on composition. Only numbers of individuals of molluscs were affected by the species of alga. Crustacea and Polychaeta showed an interaction of the species of alga with shore. In the case of this study, it is likely that the three species of macroalgae mitigate biological stressors such as predation and physical stressors such as wave exposure and desiccation. In general, meso-scale upwelling is suggested to be marginalised when considering the structuring of assemblages associated with macroalgae, while large scale biogeography has more of an influence. Within shores, assemblages were also strongly influenced by smaller-scale factors such as differences in the structure and species of alga. This study indicates the importance of investigating patterns across a range of spatial scales to gain a comprehensive understanding of factors influencing intertidal organisms.