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41.
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   
42.
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   
43.
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   
44.
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   
45.
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   
46.
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   
47.
Regional Environmental Change - This paper synthesizes what is known about the physical and biophysical impacts of climate change and their consequences for societies and development under...  相似文献   
48.
Naturally occurring arsenic in groundwater in Bangladesh poses a well-known public health threat. The aim of the present study is to investigate fostering and hindering factors of people's use of deep tubewells that provide arsenic-safe drinking water, derived from the Protection Motivation Theory and the Theory of Planned Behavior. Structured personal interviews were conducted with 222 households in rural Sreenagar, Bangladesh. Multiple linear regressions were carried out to identify the most influential personal, social, and situational behavior determinants. Data revealed that social factors explained greater variance in the consumption of drinking water from deep tubewells than did situational and personal factors. In an overall regression, social factors played the biggest role. In particular, social norms seem to strongly influence deep tubewell use. But also self-efficacy and the perceived taste of shallow tubewell water proved influential. Concurrently considering other important factors, such as the most mentioned response cost (i.e., time needed to collect deep tubewell water), we propose a socially viable procedure for installing deep tubewells for the extended consumption of arsenic-safe drinking water by the Bangladeshi population.  相似文献   
49.
To date, only three types of full-length mariner elements have been described in ants, each one in a different genus of the Myrmicinae subfamily: Sinvmar was isolated from various Solenopsis species, Myrmar from Myrmica ruginodis, and Mboumar from Messor bouvieri. In this study, we report the coexistence of three mariner elements (Tnigmar-Si, Tnigmar-Mr, and Tnigmar-Mb) in the genome of a single species, Tapinoma nigerrimum (subfamily Dolichoderinae). Molecular evolutionary analyses of the nucleotide sequence data revealed a general agreement between the evolutionary history of most the elements and the ant species that harbour them, and suggest that they are at the vertical inactivation stage of the so-called Mariner Life Cycle. In contrast, significantly reduced levels of synonymous divergence between Mboumar and Tnigmar-Mb and between Myrmar and Botmar (a mariner element isolated from Bombus terrestris), relative to those observed between their hosts, suggest that these elements arrived to the species that host them by horizontal transfer, long after the species?? split. The horizontal transfer events for the two pairs of elements could be roughly dated within the last 2 million years and about 14 million years, respectively. As would be expected under this scenario, the coding sequences of the youngest elements, Tnigmar-Mb and Mboumar, are intact and, thus, potentially functional. Each mariner element has a different chromosomal distribution pattern according to their stage within the Mariner Life Cycle. Finally, a new defective transposable element (Azteca) has also been found inserted into the Tnigmar-Mr sequences showing that the ant genomes have been invaded by at least four different types of mariner elements.  相似文献   
50.
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