991 resultados para Territorial Grazers
Resumo:
Many coral reef fish possess ultraviolet (UV) colour patterns. The behavioural significance of these patterns is poorly understood and experiments on this issue have not been reported for free-living reef fish in their natural environment. The damselfish Pomacentrus amboinensis has UV facial patterns, and spectroradiometric ocular media measurements show that it has the potential for UV vision. To test the potential behavioural significance of the UV patterns, I studied the response of males, in natural territories on the reef and in aquaria, to two conspecific intruders, one presented in a UV-transmitting (UV+) container and the other in a UV-absorbing (UV-) one. Territory owners attacked intruders viewed through UV+ filters significantly more often and for longer than intruders viewed through the UV- filter. In general, the results of the field experiment confirmed those of the laboratory experiment. The results support the hypothesis that P. amboinensis males are sensitive to UV light and that reflectance patterns, which appear in high contrast only in UV, modulate the level of aggressive behaviour. A recent survey showed that many predatory fish may not have UV vision and the use of UV colours in select species of reef fish may therefore serve as a 'private communication channel'. (C) 2004 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
Resumo:
Purpose: To understand the tensions that servitization activities create between actors within networks. Design/methodology/approach: Interviews were conducted with manufacturers, intermediaries and customers across a range of industrial sectors. Findings: Tensions relating to two key sets of capabilities are identified: in developing or acquiring (i) operant technical expertise and (ii) operand service infrastructure. The former tension concerns whom knowledge is co-created with and where expertise resides. The latter involves a territorial investment component; firms developing strategies to acquire greater access to, or ownership of, infrastructures closer to customers. Developing and acquiring these capabilities is a strategic decision on the part of managers of servitizing firms, in order to gain recognized power and control in a particular territory. Originality/value: This paper explores how firms’ servitization activities involve value appropriation (from the rest of the network), contrasting with the narrative norm for servitization: that it creates additional value. There is a need to understand the tensions that servitization activities create within networks. Some firms may be able to improve servitization performance through co-operation rather than competition, generating co-opetitive relationships. Others may need to become much more aggressive, if they are to take a greater share of the ‘value’ from the value chain.
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This article offers an initial impact assessment regarding the introduction of new legislative responsibilities at the Land level in a case study of prisons policy (Strafvollzug). Combining an analysis of new legislation produced across the 16 Länder since the responsibility for prisons policy was transferred to the Land level, and insights into the mechanics of policy development obtained through a series of interviews with senior politicians and officials, this article finds that the desire among Länder to legislative independently has varied, with substantial backing for co-ordination in the development of new legislation. This has helped to confound expectations of a ‘competition of harshness’ which many expected to result from decentralisation. However, even before the 2006 reforms, there were substantial variations between the Länder when it came to implementing prisons policy, so consideration of the sub-national level in this area remains essential.
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Trophic downgrading of ecosystems necessitates a functional understanding of trophic cascades. Identifying the presence of cascades, and the mechanisms through which they occur, is particularly important for seagrass meadows, which are among the most threatened ecosystems on Earth. Shark Bay, Western Australia provides a model system to investigate the potential importance of top-down effects in a relatively pristine seagrass ecosystem. The role of megagrazers in the Shark Bay system has been previously investigated, but the role of macrograzers (i.e., teleosts), and their importance relative to megagrazers, remains unknown. The objective of my dissertation was to elucidate the importance of teleost macrograzers in transmitting top-down effects in seagrass ecosystems. Seagrasses and macroalgae were the main food of the abundant teleost Pelates octolineatus, but stable isotopic values suggested that algae may contribute a larger portion of assimilated food than suggested by gut contents. Pelates octolineatus is at risk from numerous predators, with pied cormorants (Phalacrocorax varius) taking the majority of tethered P. octolineatus. Using a combination of fish trapping and unbaited underwater video surveillance, I found that the relative abundance of P. octolineatus was greater in interior areas of seagrass banks during the cold season, and that the mean length of P. octolineatus was greater in these areas compared to along edges of banks. Finally, I used seagrass transplants and exclosure experiments to determine the relative effect of megagrazers and macrograzers on the establishment and persistence of three species of seagrasses in interior microhabitats. Teleost grazing had the largest impact on seagrass species with the highest nutrient content, and these impacts were primarily observed during the warm season. My findings are consistent with predictions of a behaviorally-mediated trophic cascade initiated by tiger sharks (Galeocerdo cuvier) and transmitted through herbivorous fishes and their predators.
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Although the effectiveness of herbivores in mitigating the effects of nutrient enrichment is well documented, few studies have examined the effects of nutrient enrichment on components of consumer fitness. Enclosures were deployed in shallow turtle grass (Thalassia testudinum) beds in Florida Bay, Florida in fall 2003, spring 2004, and fall 2004 to measure the effects of nitrogen and phosphorous enrichment on the growth, fecundity, and stoichiometry of three invertebrate epiphyte grazers commonly associated with T. testudinum. The gastropod Turbo castanea exhibited significantly greater wet weight gain and lower C:P and N:P in enriched than in ambient treatments. Although nutrient enrichment did not have any significant effects on the growth of caridean shrimp (treatment consisted of several different caridean shrimp species), their C:N was significantly lower in enriched treatments. The final size and stoichiometry of the hermit crab Paguristes tortugae was not significantly affected by nutrient enrichment, nor did nutrient enrichment significantly affect the fecundity of P. tortugae, the only grazer in which gravid individuals or egg masses were present. Our study demonstrated that nutrient enrichment of primary producers can positively affect the growth of marine invertebrate grazers and alter their stoichiometry; however, these effects were species-specific and may be dependent upon the life stage, specific diets, and/or compensatory feeding habits of the grazers.
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Disasters are complex events characterized by damage to key infrastructure and population displacements into disaster shelters. Assessing the living environment in shelters during disasters is a crucial health security concern. Until now, jurisdictional knowledge and preparedness on those assessment methods, or deficiencies found in shelters is limited. A cross-sectional survey (STUSA survey) ascertained knowledge and preparedness for those assessments in all 50 states, DC, and 5 US territories. Descriptive analysis of overall knowledge and preparedness was performed. Fisher’s exact statistics analyzed differences between two groups: jurisdiction type and population size. Two logistic regression models analyzed earthquakes and hurricane risks as predictors of knowledge and preparedness. A convenience sample of state shelter assessments records (n=116) was analyzed to describe environmental health deficiencies found during selected events. Overall, 55 (98%) of jurisdictions responded (states and territories) and appeared to be knowledgeable of these assessments (states 92%, territories 100%, p = 1.000), and engaged in disaster planning with shelter partners (states 96%, territories 83%, p = 0.564). Few had shelter assessment procedures (states 53%, territories 50%, p = 1.000); or training in disaster shelter assessments (states 41%, 60% territories, p = 0.638). Knowledge or preparedness was not predicted by disaster risks, population size, and jurisdiction type in neither model. Knowledge: hurricane (Adjusted OR 0.69, 95% C.I. 0.06-7.88); earthquake (OR 0.82, 95% C.I. 0.17-4.06); and both risks (OR 1.44, 95% C.I. 0.24-8.63); preparedness model: hurricane (OR 1.91, 95% C.I. 0.06-20.69); earthquake (OR 0.47, 95% C.I. 0.7-3.17); and both risks (OR 0.50, 95% C.I. 0.06-3.94). Environmental health deficiencies documented in shelter assessments occurred mostly in: sanitation (30%); facility (17%); food (15%); and sleeping areas (12%); and during ice storms and tornadoes. More research is needed in the area of environmental health assessments of disaster shelters, particularly, in those areas that may provide better insight into the living environment of all shelter occupants and potential effects in disaster morbidity and mortality. Also, to evaluate the effectiveness and usefulness of these assessments methods and the data available on environmental health deficiencies in risk management to protect those at greater risk in shelter facilities during disasters.
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Os estudos da territorialidade e de comportamentos associados a ela favorecem o entendimento da maneira como as interações ecológicas afetam a composição de espécies e a dinâmica de uma comunidade. No presente estudo tivemos como objetivo geral investigar o comportamento de Stegastes fuscus, um peixe-donzela territorialista, em ambiente natural e em cativeiro, com foco na capacidade de localização territorial, reconhecimento e defesa de uma área estabelecida. Para tanto subdividimos o trabalho em 3 capítulos. O primeiro teve como foco o estudo da espécie em ambiente natural objetivando estimar a área do território ocupado e os padrões comportamentais da por ela expressos. Sendo encontrado que a área média ocupada por S. fuscus foi de 274 cm2 e os comportamentos mais observados foram: vigilância, ingestão de alimento, tempo no abrigo/toca e displays agressivos. O segundo capítulo teve como alvo investigar a capacidade de localização espacial da espécie mediada por pistas visuais. Os resultados demonstraram que S. fuscus apresenta marcante aprendizagem condicionada e possibilidade de existência de orientação espacial na espécie. O terceiro capítulo teve como objetivo avaliar a influência da residência prévia estabelecida e do reconhecimento de coespecíficos nos resultados de confrontos agonísticos. Os resultados apontaram a residência como fator prioritário na dinâmica das disputas agonísticas e que aspectos relacionados à familiaridade como relevantes e destacam-se mais quando não existe um território previamente estabelecido. Diante disso nossos resultados podem favorecer o entendimento da dinâmica estrutural da comunidade na qual S. fuscus esta inserida, sendo isto significativo tendo em vista a importância ecológica da espécie para o ecossistema.
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Este trabajo clarifica conceptos ambiguos e imprecisos como "territorio de la Unión"; se cosntata que el territorio es de los Estados miembros. También puntualiza las diferencias entre territorio y ámbito de aplicación territorial del derecho de la Unión. Analiza diversos aspectos relativos a las fronteras interiores y exteriores; establece la relación entre el respeto a las fronteras de los Estados y la defensa de la integridad territorial del Estado.
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La comunicación que presentamos se basa en el importante movimiento ciudadano desarrollado en defensa de la Vega de Granada para reflexionar sobre un aspecto que nos parece cada vez más preocupante: la falta de un consenso social, cuando no rechazo, sobre la protección de los bienes culturales de carácter territorial, especialmente los paisajes culturales, mediante la legislación de Patrimonio Cultural. Este rechazo, que hemos denominado BICtitis, está teniendo un impacto significativo en los principios de protección del Patrimonio Cultural: el predominio de los instrumentos de planificación urbana y territorial sobre las declaraciones de Patrimonio, la naturalización de los bienes culturales territoriales o la excesiva importancia otorgada a la opinión de la población afectada. Una vez identificados todos estos efectos nocivos, realizamos una serie de propuestas para defender la validez de la utilización de la legislación del Patrimonio Cultural en la preservación de los bienes de carácter territorial.