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71.
During recent decades anthropogenic activities have dramatically impacted the Black Sea ecosystem. High levels of riverine nutrient input during the 1970s and 1980s caused eutrophic conditions including intense algal blooms resulting in hypoxia and the subsequent collapse of benthic habitats on the northwestern shelf. Intense fishing pressure also depleted stocks of many apex predators, contributing to an increase in planktivorous fish that are now the focus of fishing efforts. Additionally, the Black Sea's ecosystem changed even further with the introduction of exotic species. Economic collapse of the surrounding socialist republics in the early 1990s resulted in decreased nutrient loading which has allowed the Black Sea ecosystem to start to recover, but under rapidly changing economic and political conditions, future recovery is uncertain.  相似文献   
72.
A 0.49-ha bioreactor landfill cell containing approximately 32,400 metric tons of municipal solid waste was constructed and operated at the Northern Oaks Recycling and Disposal Facility in Harrison, Michigan, USA. Design of this full-scale research cell included a network of 48 temperature and moisture sensors, leachate collection basins, and gas sampling ports, which provided for continuous temperature and moisture data and periodic measurements of both the quantity and composition of the leachate and gas produced. The data indicated that methane generation started approximately 3 months after filling in lifts that were placed during summer, but not until 8 months for those filled during the winter. Temperature data indicated that near-0 degrees C temperatures persisted within the lifts filled during winter for more than 6 months, and that gas production was minimal during this period. These results suggest that in addition to maintaining optimal moisture levels within the waste mass, temperature control must be a key design consideration in cold climates.  相似文献   
73.
Most of the detrimental effects of using conventional insecticides to control crop pests are now well identified and are nowadays major arguments for replacing such compounds by the use of biological control agents. In this respect, the bacterium Bacillus thuringiensis var. kurstaki and Trichogramma (Hymenoptera: Trichogrammatidae) parasitic wasp species are both effective against lepidopterous pests and can actually be used concomitantly. In this work, we studied the potential side effects of B. thuringiensis var. kurstaki on Trichogramma chilonis females. We first evidenced an acute toxicity of B. thuringiensis on T. chilonis. Then, after ingestion of B. thuringiensis at sublethal doses, we focused on life history traits of T. chilonis such as longevity, reproductive success and the time spent on host eggs patches. The reproductive success of T. chilonis was not modified by B. thuringiensis while a significant effect was observed on longevity and the time spent on host eggs patches. The physiological and ecological meanings of the results obtained are discussed.  相似文献   
74.
Current United States National Park Service (NPS) management is challenged to balance visitor use with the environmental and social consequences of automobile use. Wildlife populations in national parks are increasingly vulnerable to road impacts. Other than isolated reports on the incidence of road-related mortality, there is little knowledge of how roads might affect wildlife populations throughout the national park system. Researchers at the Western Transportation Institute synthesized information obtained from a system-wide survey of resource managers to assess the magnitude of their concerns on the impacts of roads on park wildlife. The results characterize current conditions and help identify wildlife-transportation conflicts. A total of 196 national park management units (NPS units) were contacted and 106 responded to our questionnaire. Park resource managers responded that over half of the NPS units’ existing transportation systems were at or above capacity, with traffic volumes currently high or very high in one quarter of them and traffic expected to increase in the majority of units. Data is not generally collected systematically on road-related mortality to wildlife, yet nearly half of the respondents believed road-caused mortality significantly affected wildlife populations. Over one-half believed habitat fragmentation was affecting wildlife populations. Despite these expressed concerns, only 36% of the NPS units used some form of mitigation method to reduce road impacts on wildlife. Nearly half of the respondents expect that these impacts would only worsen in the next five years. Our results underscore the importance for a more systematic approach to address wildlife-roadway conflicts for a situation that is expected to increase in the next five to ten years.  相似文献   
75.
BioScene (scenarios for reconciling biodiversity conservation with declining agriculture use in mountain areas in Europe) was a three-year project (2002–2005) funded by the European Union’s Fifth Framework Programme, and aimed to investigate the implications of agricultural restructuring and decline for biodiversity conservation in the mountain areas of Europe. The research took a case study approach to the analysis of the biodiversity processes and outcomes of different scenarios of agri-environmental change in six countries (France, Greece, Norway, Slovakia, Switzerland, and the United Kingdom) covering the major biogeographical regions of Europe. The project was coordinated by Imperial College London, and each study area had a multidisciplinary team including ecologists and social and economic experts, which sought a comprehensive understanding of the drivers for change and their implications for sustainability. A key component was the sustainability assessment (SA) of the alternative scenarios. This article discusses the development and application of the SA methodology developed for BioScene. While the methodology was objectives-led, it was also strongly grounded in baseline ecological and socio-economic data. This article also describes the engagement of stakeholder panels in each study area and the use of causal chain analysis for understanding the likely implications for land use and biodiversity of strategic drivers of change under alternative scenarios for agriculture and rural policy and for biodiversity management. Finally, this article draws conclusions for the application of SA more widely, its use with scenarios, and the benefits of stakeholder engagement in the SA process.  相似文献   
76.
Journal of Polymers and the Environment - Polyvinylidene fluoride (PVDF)/g-C3N4/Chitosan thin film membranes were prepared by immersing of PVDF/g-C3N4 membrane in solution containing various...  相似文献   
77.
Animals can profit from increasing temperatures by prolonged breeding seasons and faster growth rates. However, these fitness benefits are traded off against higher parasite load and increased virulence of temperature-sensitive pathogens. In thermally stratified habitats, behavioral plasticity can allow hosts to choose the optimal temperature to enhance individual fitness and to escape parasite pressure. To test this idea, we performed a temperature choice experiment with the host–parasite system of the sex-role reversed broad-nosed pipefish (Syngnathus typhle) and its bacterial pathogen Vibrio spp. In this species, pregnant males are expected to face a trade-off between shortening their brooding period in warm water and decreasing the effect of the infection in cold water. We found that exposure to Vibrio changed the temperature preference for both pregnant and nonpregnant males, as well as females compared to nonchallenged fish that tended to prefer warm water. This study shows that behavioral plasticity is one option for avoidance of higher bacterial prevalence, as expected due to rising ocean temperatures.  相似文献   
78.
Using known occurrences of species and correlational modeling approaches has become a common paradigm in broad-scale ecology and biogeography, yet important aspects of the methodology remain little-explored in terms of conceptual basis. Here, we explore the conceptual and empirical reasons behind choice of extent of study area in such analyses, and offer practical, but conceptually justified, reasoning for such decisions. We assert that the area that has been accessible to the species of interest over relevant time periods represents the ideal area for model development, testing, and comparison.  相似文献   
79.
The importance of improving the effectiveness of Plan EIA and SEA-type evaluations in China cannot be overstated: at a time when the country's economy is being boosted by a stimulus package worth over RMB 400 trillion – largely for infrastructure – the pressure on China's already strained environment and resource base is bound to increase. The aim is to propose the criteria for plan EIA's effectiveness to raise the awareness of the need to strengthen the performance of the assessment and maximize its potential benefits. The authors first review critically the discourse on the effectiveness of the impact assessment, identifying three dimensions: substantive, procedural and incremental. The resulting conceptual framework allows them to interpret the weaknesses of the Chinese discourse on the effectiveness and of the practice of the Plan EIA to date. The result is the identification of a clear gap, both in terms of the breadth of the concept, and in terms of the quality of the existing criteria, which tend to be very generic to the point of inapplicability. The analysis also reveals a need for transitioning from formal models of the Plan EIA to more strategic approaches, in a gradual manner that is consistent with context-specificities. The proposal of a set of preliminary criteria for effectiveness is therefore structured on three levels. This framework is meant to input into the ongoing debate on how to improve the practice of PEIA and the SEA-type evaluations in China, and provide ideas for a government strategy aimed at maximizing the positive impact of PEIAs on planning, as well as on the context of application.  相似文献   
80.
Perceived failure to reduce greenhouse gas emissions has prompted interest in avoiding the harms of climate change via geoengineering, that is, the intentional manipulation of Earth system processes. Perhaps the most promising geoengineering technique is stratospheric aerosol injection (SAI), which reflects incoming solar radiation, thereby lowering surface temperatures. This paper analyzes a scenario in which SAI brings great harm on its own. The scenario is based on the issue of SAI intermittency, in which aerosol injection is halted, sending temperatures rapidly back toward where they would have been without SAI. The rapid temperature increase could be quite damaging, which in turn creates a strong incentive to avoid intermittency. In the scenario, a catastrophic societal collapse eliminates society’s ability to continue SAI, despite the incentive. The collapse could be caused by a pandemic, nuclear war, or other global catastrophe. The ensuing intermittency hits a population that is already vulnerable from the initial collapse, making for a double catastrophe. While the outcomes of the double catastrophe are difficult to predict, plausible worst-case scenarios include human extinction. The decision to implement SAI is found to depend on whether global catastrophe is more likely from double catastrophe or from climate change alone. The SAI double catastrophe scenario also strengthens arguments for greenhouse gas emissions reductions and against SAI, as well as for building communities that could be self-sufficient during global catastrophes. Finally, the paper demonstrates the value of integrative, systems-based global catastrophic risk analysis.  相似文献   
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