Fish predation can have structuring effects in aquatic communities, but the most important fish predators are not always immediately obvious. Generalist fish predators often occupy similar habitats and consume similar prey making determination of their consumptive impacts difficult. Understanding these consumptive impacts is important for understanding complex wetland food webs. I collected warmouth (Lepomis gulosus), bluespotted sunfish (Enneacanthus gloriosus), and dollar sunfish (Lepomis marginatus) in two seasons from sloughs for both diet and bioenergetics analysis. Macroinvertebrates dominated diets of the three species, and nonparametric analyses revealed evidence of diet ontogeny in warmouth and potential competition for prey items among gape-matched individuals. Bioenergetics modeling revealed high levels of macroinvertebrate comsumption by these species relative to macroinvertebrate reproductive output suggesting that when combined with other sources of mortality, consumptive pressures placed by sunfish on benthic macroinvertebrates may be quite large. / by Jacob Bransky. / Thesis (M.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

A complexidade estrutural do habitat é considerada um fator importante que influencia a dinâmica populacional e a organização trófica dos artrópodes na natureza. Com o aumento da estrutura do habitat, aumenta-se a ocorrência de fontes alternativas de alimento e os organismos podem aumentar o seu fitness ao se alimentar de uma dieta mista. Por outro lado, ao forragear em busca de misturar sua alimentação e incrementar seu fitness, o predador se expõe a interações que podem não ser benéficas, a exemplo da predação intraguilda. O presente trabalho foi dividido em dois capítulos. No primeiro capítulo foi investigada a capacidade do ácaro Euseius concordis em percorrer grandes distâncias para misturar sua dieta, ao passo que foi verificado a existência de custos envolvidos para obter a dieta. No segundo capítulo foi avaliada a ocorrência de predação intraguilda recíproca entre duas espécies de ácaros predadores Iphiseiodes zulaguai e E. concordis, os quais são considerados potenciais agentes de controle biológico em diversas culturas. Os resultados indicam que E. concordis não forrageou longas distâncias de modo a misturar sua dieta. Além disso, I. zulaguai e E. concordis interagiram por meio da predação intraguilda recíproca. Finalmente, este estudo demonstra que a estrutura do habitat está ligada diretamente com a dinâmica populacional do artrópode. Esses resultados podem ser aplicados a outros sistemas de cultivos, tanto florestais quanto agrícolas. / The structural complexity of the habitat is considered an important factor that influences the population dynamics and the trophic organization of arthropods in nature. As the habitat structure increases, alternative sources of food increase and organisms can increase their fitness by eating a mixed diet. On the other hand, when foraging in search of mixing their food and increasing their fitness the predator is exposed to interactions that may not be beneficial, such as intraguild predation. The present work, divided in two chapters, the first chapter investigated the ability of the mite Euseius concordis to travel great distances to mix their diet, while it was verified the existence of costs involved to obtain the diet. In the second chapter, the occurrence of reciprocal intraguild predation between two predatory mite species Iphiseiodes zulaguai and E. concordis, which are considered as potential biological control agents, was evaluated. The results indicate that E. concordis did not forage long distances in order to mix their diet. In addition, I. zulaguai and E. concordis interacted through reciprocal intraguild predation. Finally, this study demonstrates that the habitat structure is directly linked to the population dynamics of arthropods.

Por um cunho bibliográfico, esta tese se debruça sobre as caçadas de certas etnografias da Amazônia indígena buscando compreender as relações, aí estabelecidas, entre as perspectivas da predação e da familiarização. Trata-se de um ensaio comparativo, inspirado no método lévi-straussiano da análise dos mitos, que justapõe para o cotejo e a análise as etnografias [1] da caça yudjá aos porcos, [2] da caça coletiva dos Arara, [3] dos mitos yaminawa sobre os encontros cinegéticos e [4] da caça awá-guajá aos guaribas. A análise comparativa das etnografias sustentará, nas considerações finais deste texto, uma proposta nova para o entendimento dos conceitos de predação e familiarização. / From a bibliographic imprint, the present dissertation bend on the hunting of certain ethnographies from the indigenous Amazonia, seeking for understanding the relationships, there establish, between the perspectives of predation and familiarization. This is a comparative essay, inspired by Lévi-Straussian method for the analysis, which juxtaposes for collation and review the ethnographies [1] of Yudjá hunting to pigs, [2] the collective hunting of the Arara people, [3] the Yaminawa\'s myths of hunting and [4] the Awá-Guajá hunting to howler monkeys. At the ultimate remarks of this manuscript, the comparative analysis of the ethnografies will sustain a different proposal to comprehend the concepts of predation and familiarization.

Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 147-160). / Predatory bacteria are ubiquitous in aquatic environments and may be important players in the ecology and biogeochemistry of microbial communities. Three novel strains belonging to two genera of marine flavobacteria, Olleya and Tenacibaculum, were cultured from coastal sediments and found to be predatory on other bacteria on surfaces. Two published species of the genus Tenacibaculum were also observed to grow by lysis of prey bacteria, raising the possibility that predation may be a widespread lifestyle amongst marine flavobacteria, which are diverse and abundant in a variety of marine environments. The marine flavobacterial clade is known to include species capable of photoheterotrophy, scavenging of polymeric organic substances, pathogenesis on animals, the degradation and lysis of phytoplankton blooms and, now, predation on bacterial communities. Strains from the two genera were found to exhibit divergent prey specificities and growth yields when growing predatorily. Olleya sp. predatory cells accumulated to an order of magnitude greater cell densities than Tenacibaculum sp. cells on equivalent prey cell densities. Experiments were conducted to constrain the potential of the novel isolates to affect prey communities under more environmentally relevant conditions. An investigation of the minimum number of predatory cells needed to generate clearings of prey cells found that the inoculation of individual predatory flavobacteria cells can ultimately result in dense lytic swarms. In some cases, the susceptibility of particular prey species to lysis by a flavobacterial predator was found to vary based on the growth state of the prey cells or the presence of their spent growth media. A novel methodology for the experimental study of biofilms was used to assess the impact of exposure to predatory marine flavobacteria on the release of macronutrients from prey biofilms. The Olleya sp. predator had a stimulative effect on macronutrient release while the Tenacibaculum sp. did not, further suggesting the two groups of predators are adapted to different ecological niches. / by Erin C. Banning. / Ph.D.

Orientador: Carlos Camargo Alberts / Banca: Fernando Frei / Banca: Beatriz de Mello Beisiegel / Resumo: Entre os grupos de vertebrados, os mamíferos carnívoros têm sido utilizados como espécies-alvo em diversos projetos ambientais. Atualmente, apresentam populações pequenas e muitas vezes em declínio classificados com algum grau de ameaça de extinção, consequência das alterações na paisagem causadas pelas atividades humanas. No Brasil, atualmente, a maior causa da diminuição das populações de mamíferos carnívoros é a redução ou perda de habitat ocasionada pela expansão agrícola, pecuária, exploração mineral e urbanização. A predação por onças-pardas tem sido documentada em diversas regiões e, como consequência, a perseguição a esses animais é fortemente observada. A fim de identificar os fatores que poderiam estar associados às predações aos rebanhos domésticos por onças-pardas no oeste do Estado de São Paulo, realizamos entrevistas com produtores rurais, utilizando para isso questionários semiestruturados, abordando características das propriedades, do manejo e da paisagem. Realizamos 54 entrevistas e identificamos propriedades que passaram por eventos de predação nos últimos oito anos. Bovino foi o grupo de animais mais frequentemente predado. Através da Regressão Logística, foi possível obter um modelo de previsão de ataques com 83% de concordância entre estimado e observado, onde o número de suínos e a distância do rio para a sede, presentes em cada propriedade, foram positivamente relacionados aos casos de predação. Através das análises das Redes Neurais Artificiais, foi possível especular a presença de um ciclo predador-presa ocorrendo entre o puma concolor e uma presa ainda desconhecida. Práticas de manejo adequadas podem reduzir significativamente as perdas de animais domésticos e assim reduzir possíveis conflitos humanos com predadores selvagens / Abstract: Among the vertebrate groups, carnivorous mammals have been used as target species in several environmental projects. Currently they present small and often declining populations, classified as with some degree of threat of extinction, consequence of the changes in landscape caused by human activities. In Brazil, the major current cause of the decline in carnivorous mammal populations is the reduction or loss of habitat caused by agricultural expansion, livestock farming, mineral exploration, and urbanization. Predation by pumas has been documented in several regions and as a consequence the chase of these animals is strongly observed. In order to identify the factors that could be linked to domestic herds predation by pumas in the west of São Paulo State, we conducted interviews with rural producers, using semi-structured questionnaires, addressing properties characteristics, management and landscape. We have made 54 interviews and identified some rural properties that experienced predation events in the last eight years. Bovines was the group most frequently predated. Throught the Logistic Regression, it was possible to get a model of prediction of attacks with 83% of agreement between estimated and observed, where the number of swines and the distance from the river to the principal house present in each property was positively related to predation cases. Through the analysis of Artificial Neural Networks it was possible to speculate the presence of a predator-prey cycle occurring between the puma concolor and a prey still unknown. Appropriate management practices can significantly reduce the losses of domestic animals and thus reduce possible human conflicts with wild predators / Mestre

The loss of large apex predators, and their subsequent reintroduction, has been identified as a substantial driver on the structure and function of ecological communities through behavioral mediated trophic cascades (BMTCs). The reintroduction of wolves (Canis lupus) to Yellowstone National Park (YNP) has served as foundational case study of BMTCs. In our system, it has been suggested that wolves have established a ‘landscape of fear’ in which the primary prey, elk (Cervus elaphus), now avoid risky places, which ultimately led to the recovery of the vegetation community. Although this case is frequently cited as a well-understood example of a landscape of fear, researchers never quantified whether elk avoided risky places, a critical component of the BMTC hypothesis. Thus, I employed numerous quantitative approaches to evaluate the role of wolves and cougars on elk habitat selection in northern Yellowstone. The results from this work suggest that the daily activity schedule of wolves provide a temporally predictable period of risk that allows elk to use risky places during safe times. As such, diel predator activity flattened (i.e., made less risky) the landscape of fear for 16 hours per day, 7 days a week, which permitted elk to forage on deciduous woody plants despite the presence of wolves. Thus, suggests that any trophic cascade in northern Yellowstone is likely driven by the consumptive effects of wolves on elk. In addition, my results suggest that daily activity patterns are an important component of predation risk, and as such, provide a predictable avenue for elk to avoid predators despite residing in an environment spatially saturated with wolves and cougars. Thus, the ability of elk to avoid predators through fine-scale spatial decisions provides support for my findings that the current spatial distribution of prey is largely driven by the consumptive effects of predators on the prey population, rather than a landscape of fear. In combination, these results suggest that the landscape of fear, and more generally, fear effects, may be of less relevance to conservation and management than direct killing within free-living, large landscapes.

Coyote (Canis latrans) predation accounts for the majority of neonatal pronghorn (Antilocapra americana) mortality in many areas and may influence local population declines. Current techniques used to manage coyote predation on wildlife species generally focus on lethal control methods. However, these methods may be controversial to the general public. Coyote sterilization is an alternative predation control method which is more acceptable to the public and has been shown to be effective in reducing sheep predation. We hypothesized that surgical sterilization of coyotes may increase pronghorn fawn survival; in the same way it reduces coyote predation on domestic sheep. Sterilization reduces the energetic need to provision coyote pups, which may decrease the predation rate on fawns by sterile coyotes. We employed tubal ligation and vasectomy of captured coyotes to maintain pair bonds and territoriality. We monitored pronghorn fawns by radio telemetry for one year pre-treatment and coyotes and pronghorn fawns one year post-treatment. We also examined the effects of sterilization on coyote territorial maintenance and survival. Survival of fawns captured in sterile coyote home ranges was higher than survival of fawns captured in intact home ranges (P = 0.078). We also found that fawn survival was consistently higher in the northern part of the study site (P = 0.081). A severe winter followed by a wet spring in 2007 did not reduce fawn survival and may have increased fawn survival (P = 0.364); however, our sample sizes did not allow us to detect significance in this relationship. Our results also supported the hypothesis that sterilization, while keeping hormonal systems intact, did not change coyote territorial behaviors. Sterile coyote packs were the same size as intact packs (P = 0.554). Sterile and intact coyote packs maintained similar home range sizes in all seasons tested (P ¡Ý 0.556). We found differences between home range and core area overlap of sterile and intact packs in some seasons, but this trend appeared to exist before the coyotes were treated. Residency rates were similar for sterile and intact coyotes (P = 0.406). We recommend coyote sterilization as a tool to boost pronghorn fawn survival in areas where fawn survival is a critical factor in pronghorn population persistence. Because these techniques have been tested under few circumstances, we recommend careful monitoring in future coyote sterilization programs.

Biological processes like species interactions and patterns such as abundance and distribution observed in nature can vary depending on the scale at which the subject of interest is evaluated. Knowing that there is no single natural scale at which systems should be studied, in this thesis, I conducted a series of basic and applied ecological approaches in order to examine the phenomena that can occur at different scales of space, time, and ecological organization. Species abundances can vary over large spatial and temporal scales. By studying the habitat use of an abundant species, which uses a wide range of habitats, insights can be gained into how seascape-scales might influence population-level patterns. Similarly, temporal scales might affect the dynamics of species that have complex life cycles where migration is involved. Therefore, in the first study I used an eight-year dataset to conduct a population-level study at broader time- and seascape- scales of an abundant species in Tampa Bay, Florida. The goal of this study was to provide the first in-depth study on the habitat use of Pinfish on the eastern Gulf of Mexico and to provide insights on how seascape-scales can influence their abundance and distribution. Predator-prey interactions can be influenced by habitat at different spatial scales. In seagrass systems, blade density can provide prey refugia at local scales, which are further embedded within the seascape-scale effect of turbidity. In the second study, I used a combination of in situ field experiments and laboratory-controlled experiments to examine and separate the effects of habitat across these local and seascape scales on the relative predation rates of tethered Pinfish (Lagodon rhomboids). The broad-scale analyses indicated that population-level differences, such as abundance patterns and distribution can be influenced by temporal and spatial scales. Field- studies showed that habitat can influence ecological interactions at local- and seascape- scales. Overall, this research demonstrates the importance of using multiple spatial and temporal scale approaches when studying ecology, especially of those organisms that move over large distances and have complex life histories.

No description available.

Thesis (M.S.)--State University of New York at Binghamton, Biology Department, 2006. / Includes bibliographical references.