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131.
Estuarine habitats, and the fish assemblages associated with them, are potentially impacted upon by many anthropogenic influences which can have a direct influence on the food resources, distribution, diversity, breeding, abundance, growth, survival and behaviour of both resident and migrant fish species. The direct and indirect coupling between ichthyofaunal communities and human impacts on estuaries reinforces the choice of this taxonomic group as a biological indicator that can assist in the formulation of environmental and ecological quality objectives, and in the setting of environmental and ecological quality standards for these systems. This review examines the rationale and value of selecting fishes as bio-indicators of human induced changes within estuaries, using examples from both the northern and southern hemispheres. The monitoring of estuarine 'health' using fish studies at the individual and community level is discussed, with an emphasis on the potential use of estuarine fishes and their monitoring and surveillance in national and international management programmes. In illustrating the above concept, examples are presented of the way in which fishes are threatened by anthropogenic impacts and of the way in which teleosts can contribute to a monitoring of estuarine ecosystem health.  相似文献   
132.
This paper analyzes data on approximately 30,000 women from a survey in Uttar Pradesh in 1995 together with the data from surveys of public and private providers of healthcare and family planning services. A framework was developed for analyzing the effects of quality of services on utilization, and for understanding the gradual evolution of the healthcare infrastructure. The empirical results from logistic regressions for use of female sterilization and IUD showed significant effects of quality of services in government and private hospitals, and of socioeconomic variables such as education, caste, and an index of household possessions. Secondly, models for infant mortality of children born in the preceding 3-year period showed significant effects of socioeconomic variables, quality of healthcare services and birth spacing. Lastly, analysis of data at a more aggregated (Primary Sampling Unit) level indicated differential effects of economic development on the quality of services available in the public and private facilities.  相似文献   
133.
基于2004—2018年的面板数据,借助脆弱性研究方法、冷热点分析法、空间变差模型和灰色预测模型探索长江经济带旅游-经济-生态系统的时空演变特征及趋势预测。研究表明:(1)2004—2018年长江经济带总体脆弱性指数在波动中上涨,各省市脆弱性指数洼地集中于东部地区且呈平稳发展态势;峰值集中于西部地区但下降趋势显著;总体可持续发展水平呈现"东部>中部>西部"的空间分布格局,但西部地区可持续发展水平可能将在未来超越中部地区。(2)长江经济带脆弱性指数集聚性在扩张,冷热点时空分布变化显著,冷点区域减少,热点区域增多,印证了总体区域的脆弱性数值在不断提升。(3)长江经济带脆弱性指数空间分异特征呈阶段性变化,"东散西集"的分异特征逐渐被打破,总体指数呈均衡化发展态势。(4)通过预测计算2019—2023年长江经济带各区域脆弱性指数,发现2019—2023年的脆弱性指数基本形成了对2014—2018年的全包围态势,长江经济带三系统脆弱性指数较高的发展隐患逐步成为现实问题。  相似文献   
134.
The non-linear, unexpected and severe responses of ecosystems to the environmental changes crossing ecological thresholds or environmental limits, necessitate the regular monitoring of the human-induced pressures to the urban ecosystems. The present study aims to introduce a spatial decision support system for sustainable environmental planning and management of urban ecosystems by establishing an Urban Carrying Capacity Load Number model (UCCLN) based on carrying capacity concepts and sustainability principles .This model, by applying 30 temporal and spatial indicators continuously monitors the environmental loads on the urban ecosystems. Environmental load was represented by load number index. It was calculated in each zone of study area (urban districts). Geographical Information System (GIS) was used to establish UCCLN model and Spatial Decision Support System (SDSS). The study area was Tehran metropolis, the capital of Iran. The results showed that none of the 115 urban districts of Tehran had optimal Total Load Number (TLN) ranging from (10 to100); 7 districts (6%) had low-to-medium range of TLN (TLN = 100–200); 11 districts (9.5%) had medium-to-high range (TLN = 200–300); 57 districts (49.5%) had high-to-very high range (TLN = 300–400); 40 districts (34.7%) had the TLN range of very high-to-critical (TLN = 400–500); and none of them had the TLN of 500. Furthermore, the results revealed that Tehran has already overshot its ecological thresholds. Not only most of the 30 indicators of environmental pressure in most of the districts (85%) had high DCC and LN scores, but also most of the 115 districts obtained high DCC, and as a result LN scores. The need for developing more efficient urban planning and management strategies to cope with the increasing environmental loads in the study area is inevitable.  相似文献   
135.
The epidemiological literature has widely documented the importance of social distancing interventions in containing the spread of the COVID-19 pandemic. However, the epidemiological measure of virus reproduction, R0, provides a myopic view of containment, especially when the absolute number of cases is still high. The paper investigates cross-country variations concerning the impact of social distancing interventions on COVID-19 incidence by employing a statistical measure of containment, which models the daily number of cases as a structural time-series, state-space vector. Countries that adopt strict lockdown policies and provide economic support in the form of income augmentations and debt relief improve the response towards the pandemic. Countries like China and South Korea have been most influential in containing the spread of infections. European nations of France, Italy, Spain and the UK are witnessing a second wave of the virus, indicating that re-opening the European economy perhaps has instigated an exponential spread.  相似文献   
136.
137.
Coffee is one of the historical socioeconomic crops. It has received an increasing attention at the global level, due to its positive interlinkage with the economic growth and on the gross domestic product for most of the producing countries, particularly, developing and least developed countries. Saudi Arabia is one of the coffee producing countries that has a relative comparative advantage of coffee cultivation. Yet, coffee cultivation has not received as much attention in Saudi Arabia as that of producing countries around the world. This study aims to assess the current state of coffee cultivation in Saudi Arabia and to investigate the potential to optimize coffee cultivation in Saudi Arabia that maximizes the net national economic return and export earnings, given limitation of cultivated areas, local market activities, and international trade activities. The study statistically analyzed primary data collected from around (65) coffee farms and traders in the study regions at the south and southwest Saudi Arabia, and optimized coffee cultivation in Saudi Arabia using LINGO optimization software. Empirical results of the study revealed the great potential of Saudi Arabia to expand coffee cultivation at south and southwest regions to meet the escalating local demand and to increase its share at the world market up to 2%. Optimization of coffee cultivation in Saudi Arabia showed a high potential to meet the local demand for coffee by producing 80.07 thousand tons grown over 2861.78 hectares and to generate a net return equivalent to $395.72 million a year, which is equivalent to $138.28 thousand per hectare and $4.94 thousand per ton of coffee. Optimizing coffee cultivation will play a substantial role to increase market share of Saudi Arabia to about 1–2% of the world market by increasing its export volume, respectively, to about 69.66 and 112.56 thousand tons, the national net economic return by about $395.86 and $395.95 million a year, and the export earnings of coffee by about $219.43–354.57 million a year, which in turns, will serve the national strategic trend to diversify the economic base and lower the dependency of incomes generated from oil exportation.  相似文献   
138.
The discovery of naturally evolved fluorescent proteins and their subsequent tuning by protein engineering provided the basis for a large family of genetically encoded biosensors that report a variety of physicochemical processes occurring in living tissue. These optogenetic reporters are powerful tools for live‐cell microscopy and quantitative analysis at the subcellular level. In this review, we present an overview of the transduction mechanisms that have been exploited for engineering these genetically encoded reporters. Finally, we discuss current and future efforts towards the combined use of various optogenetic actuators and reporters for simultaneously controlling and imaging the physiology of cells and tissues.  相似文献   
139.
经济开发区生态规划与建设研究   总被引:4,自引:0,他引:4  
陈涛  崔秋 《应用生态学报》1992,3(4):378-385
生态规划和建设是协调经济发展和生态环境关系,创造和谐的人工化环境的调控对策。木文研究了沈阳开发区生态规划和建设的理论、方法,着重探讨了开发区经济、环境协调发展的途径:1)选择理想的协调发展优化方案,2)控制发展热电生产,发展集中供热和低能耗高技术产业,3)节约水资源,提高水循环利用率,4)在生态学原理指导下进行生态管理。  相似文献   
140.
There have been considerable advances in our understanding of the tolerance of species interaction networks to sequential extinctions of plants and animals. However, communities of species exist in a mosaic of habitats, and the vulnerability of habitats to anthropogenic change varies. Here, we model the cascading effects of habitat loss, driven by plant extinctions, on the robustness of multiple animal groups. Our network is constructed from empirical observations of 11 animal groups in 12 habitats on farmland. We simulated sequential habitat removal scenarios: randomly; according to prior information; and with a genetic algorithm to identify best‐ and worst‐case permutations of habitat loss. We identified two semi‐natural habitats (waste ground and hedgerows together comprising < 5% of the total area of the farm) as disproportionately important to the integrity of the overall network. Our approach provides a new tool for network ecologists and for directing the management and restoration of multiple‐habitat sites.  相似文献   
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