资源开发、环境保护与地球物理学     

蒋宏耀  张立敏 《地球物理学进展》1992,(2)

人口、资源、灾害与环境是困扰当代人类的几个重大问题.人口的增长,要求有更多的资源,而资源开发、利用的合理与否,又势必对环境产生有利或有害的影响;环境的改善或恶化,反过来又必然影响到资源的增减.因此,如何处理好它们之间的关系,使资源得到合理的开发和利用,同时又保护或改善环境,形成资源开发利用与环境保护改善之间的良性循环,应当是人类共同奋斗的一个目标. 本文依据一些实际资料论述了上述问题以及地球物理学在解决这些问题中所应起的作用.  相似文献   

Measuring molecular variation in zooplankton populations: DNA extraction from smallDaphnia species     

Mona A. Mort  Bruno Streit 《Aquatic Sciences - Research Across Boundaries》1992,54(1):77-84

We present methods developed for the small-sizedDaphnia species,D. galeata, D. hyalina, D. cucullata, and their hybrids, which facilitate the use of DNA variation in population studies. Described are large-scale production of material from single genotypes ofDaphnia and subsequent extraction of total DNA. The average DNA yields ranged between 6 µg per gram wet weight (D. cucullata) and 12 µg per gram wet weight (D. galeata). For comparison, the large-sized speciesD. pulex was tested and yielded an average of 28 µg DNA per gram wet weight. The DNA isolated in this manner lends itself well to molecular genetic techniques suited for population studies.Reprint requests to B. Streit.  相似文献   

A Study of Global Change Population and Economic System Risk Forming Mechanism and Assessment     

Shi Peijun  Wang Aihui  Sun Fubao  Li Ning  Ye Tao  Xu Wei  Wang Jing&#x  ai  Yang Jianping  Zhou Hongjian 《地球科学进展》2016,31(8):775-781

Global climate change featured with warming has created serious challenge to world sustainable development and human security. It has become an important consensus of the international society to assess global change risk at the global scale and carry out tailored governance and risk-based adaptation. National Key Research and Development Program “Study on global change population and economic system risk forming mechanism and assessment” aims at quantitatively predicting future global climate change and population and economic system exposure and vulnerability change, developing global change population and economic system risk assessment model based on complex system dynamics, synthesizing risk assessment model with proprietary intellectual property rights, assess global change population and economic system risk of the near and mid future at the global scale, and compiling the atlas of global change population and economic system risk. The outcomes intend to serve the participation of global risk governance and international climate negotiation, and to provide scientific support to the implementation of international disaster risk reduction strategy.  相似文献   

Dams and population displacement on China’s Upper Mekong River: Implications for social capital and social–ecological resilience     

《Global Environmental Change》2016

China is home to nearly half of the world’s 50,000 large dams, which provide irrigation, flood protection, and hydroelectricity. Most of these projects involve substantial population displacement, which can disrupt social capital, the webs of interdependence and support that community members maintain with one another through relationships of trust and reciprocity. We use new empirical evidence to examine the association between dam-induced displacement and social capital in China and interpret our findings in the context of social–ecological resilience theory. Our focus is on agricultural households on the Upper Mekong River, where four large hydropower dams have been constructed over the past twenty years.Our broad finding is that resettlement is associated with diminished social capital, as measured by two key indicators: inter-household exchange of financial resources, and inter-household exchange of agricultural labor. These effects differ across the four dam sites in the study based on local economic conditions and changes in resettlement policy. We find that population resettlement is associated with markedly lower levels of agricultural labor exchange. In an economically under-developed setting, this reduces the depth and breadth of social support that agricultural households rely on to produce crops for subsistence and income. This in turn diminishes social–ecological resilience because social capital is a key factor that helps agricultural or resource-dependent communities manage risk and adapt to changes and stressors.We consider the policy implications of our findings in the context of scientific and industry efforts to minimize social harm, promote economic vitality, and improve the sustainability of hydropower as a form of renewable energy.  相似文献   

Wasp-waist populations and marine ecosystem dynamics: Navigating the “predator pit” topographies     

Andrew Bakun 《Progress in Oceanography》2006,68(2-4):271

Many marine ecosystems exhibit a characteristic “wasp-waist” structure, where a single species, or at most several species, of small planktivorous fishes entirely dominate their trophic level. These species have complex life histories that result in radical variability that may propagate to both higher and lower trophic levels of the ecosystem. In addition, these populations have two key attributes: (1) they represent the lowest trophic level that is mobile, so they are capable of relocating their area of operation according to their own internal dynamics; (2) they may prey upon the early life stages of their predators, forming an unstable feedback loop in the trophic system that may, for example, precipitate abrupt regime shifts. Experience with the typical “boom-bust” dynamics of this type of population, and with populations that interact trophically with them, suggests a “predator pit” type of dynamics. This features a refuge from predation when abundance is very low, very destructive predation between an abundance level sufficient to attract interest from predators and an abundance level sufficient to satiate available predators, and, as abundance increases beyond this satiation point, decreasing specific predation mortality and population breakout. A simple formalism is developed to describe these dynamics. Examples of its application include (a) a hypothetical mechanism for progressive geographical habitat expansion at high biomass, (b) an explanation for the out-of-phase alternations of abundances of anchovies and sardines in many regional systems that appear to occur without substantial adverse interactions between the two species groups, and (c) an account of an interaction of environmental processes and fishery exploitation that caused a regime shift. The last is the example of the Baltic Sea, where the cod resource collapsed in concert with establishment of dominance of that ecosystem by the cod’s ‘wasp-waist” prey, herring and sprat.  相似文献   

Vegetation of Mangroves： Spatial and Temporal Pattern of itsDominant Populations in Futian National Nature Reserve     

LiZhenji ZhengWenjiao YangZhiwei LinYiming LinPeng 《海洋通报(英文版)》2003,5(2):40-53

The community characteristics of mangroves in the Futian Nature Reserve,Shenzhen, China are given based on surveying of 33 quadrats in 4 transects which stretch from the higher tidal zone to the lower tidal zone. The results show that there are 6 community types in this area: Kandelia candel association, Avicennia marina association, A egiceras corniculatum association, Kandelia candel Aegiceras corniculatum association,degiceras corniculatum Kandelia candel association and Acanthus ilicifolius association.Kandelia candel, degiceras corniculatum and dvicennia marina dominate the typicalquadrats. Kandelia candel can be seen at almost all quadrats, Aegiceras corniculatumdistributes mostly toward the estuary and the higher tidal zone, Avicennia marina distributesmostly toward the bay and the lower tidal zone, Bruguiera gymnorrhiza occasionally occurs toward the Estuary with one or several individuals, Acanthus ilicifolius was common towardthe higher tidal zone, as an accompanying species, Derris trifoliata was common in manymature ouadrats. Totallv. 6 snecies of man~rove plants and 3 soecies of semi-mangrove plants appear in this research area. From the higher tidal zone to the lower tidal zone, the average diameter and basal area of mangrove trees increase gradually. According to the results, the dvicennia marina dominates in average diameter and basal area, and the degicerascorniculatum trees are on the contrary. From the transect ! to the transect 4, the importance value ot dvicennia marina, Bruguiera gymnorrhiza and Kandelia candel decreases, and degiceras corniculatum increases. In this area, the Kandelia candel population and Ae giceras corniculatum population are developing populations with many seedlings and saplings, but the Avicennia marina population is in a mature stage with few seedlings and not so many total individuals. According to this research, we suppose that Aegiceras corniculatum should be developed toward the estuary and the dvicennia marina association should be protected.  相似文献   

南极夏季普里兹湾桡足类优势种的产卵量和种群结构     

张光涛  孙松 《海洋与湖沼》2002,33(2):196-202

1998年12月－1999年1月在南极普里兹湾采用现场培养的方法对大、中型桡足类优势种尖角似哲水蚤（Calanoides acutus)、戈氏长腹水蚤（Metridia gerlachei)和巨锚哲水蚤（Rhincalanus gigas)进行了实验研究，同时根据浮游动物垂直拖网的样品分析了它们的种群结构。结果表明，在实验中，C.acutus和M.gerlachei的平均产卵量分别为13.3(5-49)和5（4－12）个／雌／天；R.gigas没有产卵。随后对获得的卵进行连续观察，所有的卵均没有孵化。通过标本分析发现，C.acutus夏季的种群结构为双峰态，尤其是陆冰缘站，新生个体主要是CI期桡足幼体，而越冬个体包括CIV、CV和雌性成体。R.gigas的种群结构特征不明显，新生个体为12月末发现的大量集中分布的无节幼体。M.gerlachei表现出和C.acutus相似的丰度分布特性，但其种群结构主要是成体和晚期幼体。  相似文献   

Toward a mechanistic understanding of larval dispersal: insights from genomic fingerprinting of the deep-sea hydrothermal vent tubeworm Riftia pachyptila     

Timothy M. Shank  & Kenneth M. Halanych 《Marine Ecology》2007,28(1):25-35

Larval dispersal is critical for the maintenance of species populations in patchy and ephemeral hydrothermal vent habitats. On fast‐spreading ridges, such as the East Pacific Rise, rates of habitat turnover are comparable to estimated lifespans of many of the inhabiting species. Traditionally, dispersal questions have been addressed with two very different approaches, larval studies and population genetics. Population genetic studies of vent‐endemic species have been informative for determining whether patterns of dispersal are suggestive of stepping stone or island models and estimating rates of gene flow (effective migrants per generation) over broad geographic ranges. However, these studies leave fundamental questions unanswered about the specific mechanisms by which larvae disperse and species maintain their populations and biogeographic ranges. With the goal of examining genetic structure and elucidating alternative larval dispersal mechanisms, we employed a genomic DNA fingerprinting technique, amplified fragment length polymorphisms (AFLPs). To assess the potential utility of AFLPs, and genetic structure of the hydrothermal vent tubeworm Riftia pachyptila, genomic ‘fingerprints’ were recovered from 29 individuals from five vent fields spanning a distance of up to c. 5000 km along the East Pacific Rise. In contrast to previous population genetic studies that found little to no genetic structure using allozymes and mitochondrial DNA, genetic analyses of 630 polymorphic AFLP loci identified distinct subclades within R. pachyptila populations. Significant levels of differentiation were observed among populations from all vent regions as well as within each region. Discrete assemblages of tubeworms separated by as little as c. 400 m within a given vent region were genetically distinguishable and cohorts (based on size‐frequency distribution) within an aggregation were found to be most closely related. These results suggest that mechanisms of larval dispersal act to retain cohort fidelity in R. pachyptila.  相似文献   

黄、渤海及东海江豚的洄游和种群差异          下载免费PDF全文

董金海  王广洁  肖志忠 《海洋科学》1993,17(5):42-45

江豚对食物没有明显的选择性,常随分布区优势饵料种类的变化而变化。探讨了江豚洄游与饵料分布的关系,并对黄、渤海和东海长江两地理种群的差异进行了比较。  相似文献   

微齿喜马拉雅低额溞生长及种群增长的研究     

施心路  于丽杰  张大维  史新柏 《海洋与湖沼》1997,28(3):262-270

于1990年6月在哈尔滨市东北林业大学实验林场一水池中采到微齿喜马拉雅低额溞，根据实验结果应用生物统计学方法对它的生长和种群增长进行研究。结果表明，在不同温度条件下性成熟时间与水温的关系为，雌性（10-30°C）：h=8072t^-1.313（r=0.985, P＜0.01）；雄性（5-25°C）：h=1074t^-0.855（r=0.9844，P＜0.01）。在20±1°C条件下，其体长增长模型为：l_t=3.334-2.7345e^-0.1117t。龄期（x）与年龄（t，d）的关系为：雌体：t=0.07169x²＋1.3808x-1.7361；雄体：t=0.8425x²＋2.534x-1.8600。内禀增长率（r_m）为0.4076。种群增长呈“logistic”型，其方程式为：y=3625/[1+e^{(3.848-0.164t)}]。  相似文献