萨罗罗非鱼(Sarotherodon melanotheron)与其他5种罗非鱼遗传多样性比较研究   总被引：2，自引：0，他引：2  

李学军  李爱景  李思发  蔡完其 《海洋与湖沼》2010,41(1):85-90

根据已知罗非鱼相关基因序列设计了5对微卫星引物,对萨罗罗非鱼、尼罗罗非鱼、以色列红罗非鱼、台湾红罗非鱼、奥利亚罗非鱼和齐氏罗非鱼6种罗非鱼进行遗传多样性分析,结果表明:(1)6种罗非鱼在5个微卫星座位上共发现22个等位基因和49种基因型,萨罗罗非鱼、台湾红罗非鱼及齐氏罗非鱼的等位基因数和基因型数较少,萨罗罗非鱼特有的等位基因是190和204,特有的基因型为190/190、204/204、270/223和270/243;(2)与另外5种罗非鱼相比,萨罗罗非鱼的有效等位基因数(Ne)、平均杂合度期望值(He)和多态信息含量值(PIC)都较低,分别为1.812、0.331和0.326;(3)6种罗非鱼明显分为2支,萨罗罗非鱼单独为一支,另外5种罗非鱼聚为一支;(4)萨罗罗非鱼保种的主要问题是要特别防止近亲繁殖。  相似文献   

Reproductive biology of Ilisha elongata (Teleostei: Pristigasteridae) in Ariake Sound,Japan: Implications for estuarine fish conservation in Asia     

Jie Zhang  Toru Takita  Chunguang Zhang 《Estuarine, Coastal and Shelf Science》2009

Elongate ilisha (Ilisha enlongata) is a commercially important species that contributes to clupeoid fisheries in Asian countries. In the present study, the reproductive biology of I. elongata in Ariake Sound, Japan is determined for the first time. Six maturity stages were described using ovarian and testicular histology throughout the annual cycle. The spawning season in Ariake Sound lasts from May to July, with peak spawning activity in May and June. Age at first maturity was estimated to be 2 years, with a few exceptions of 1 year in well-developed males. Ovaries that contained both tertiary yolk oocytes and postovulatory follicles occurred from late May to late July, indicating that I. elongata is a multiple spawner. The size–frequency distribution of oocytes provided evidence for its multiple spawning and accuracy of the fecundity estimates. The batch fecundity of this species was estimated at between 22,200 and 270,900 eggs per individual, increasing with age between two and six years. The present findings on the reproductive strategy of I. elongata in Ariake Sound are generally consistent with those in temperate or subtropical populations, but quite different from those of tropical population where first maturation occurs around 200 days and life spans are shorter, with a maximum age less than 3 years. The conservation implications of this reproductive strategy in a harsh, variable environment in Asian countries are also discussed.  相似文献   

应用能量法反演地球重力场     

王伟  罗佳  汪海洪 《测绘信息与工程》2009,34(3):12-13

分析了能量法反演地球重力场的原理和关键技术,研究了法方程矩阵求解和加速度计校准的方法,评述了能量法求取地球重力场需要注意的问题。  相似文献   

Effects of terracing and agroforestry on soil and water loss in hilly areas of the Sichuan Basin,China   总被引：1，自引：0，他引：1  

J. H. Zhang  Z. A. Su  G. C. Liu 《山地科学学报》2008,5(3):241-248

Soil erosion in hilly areas of the Sichuan Basin is a serious concern over sustainable crop production and sound ecosystem. A 3-year experiment was conducted using the method of runoff plots to examine the effects of terracing and agroforestry in farmland systems on soil and water conservation of slope fields in the hilly areas in Jianyang County, Sichuan Province, Southwestern China. A power function （Y = aX^b） can statistically describe the relationship between water runoff （Y） and rainfall （X）. The regression equation for the treatment of sloping terraces with crops （Plot 2） is remarkably different from that for the treatment of sloping terraces with grasses and trees （Plot 1） and the conventional up- and down-slope crop system （Plot 3） regarding equation coefficients, while regression equations are similar between Plot 1 and Plot 3. Water runoff amount and runoff coefficient of slope fields increased by 21.5-41.0 % and 27.5 - 69.7 % respectively, compared to those of sloping terraces, suggesting that terracing notably reduced the water runoff in the field. In the case of sloping terraces, lower amount of water runoff was observed on sloping terraces with crops than on sloping terraces with grasses and trees. Sediment yields on the slope fields in the normal year of rainfall distribution were notably higher （34.41 - 331.67 % and 37.06-403.44 % for Plot 1 and Plot 2, respectively） than those on sloping terraces, implying that terracing also plays a significant role in the reduction in soil erosion. It is suggested that terracing with crops is significantly effective for soil and water conservation in cultivated farmland, while the conventional practice of up- and down- slope cultivation creates high rates of water runoff and soil sediment transport. Terracing with grasses and fruit trees shows a less reduction in water runoff than terracing with crops, which was observed in the 3-year experiments.  相似文献   

Analyzing the habitat suitability for migratory birds at the Chongming Dongtan Nature Reserve in Shanghai,China   总被引：1，自引：0，他引：1  

Bo Tian  Yunxuan Zhou  Liquan Zhang  Lin Yuan 《Estuarine, Coastal and Shelf Science》2008

The Dongtan Nature Reserve, one of the largest nature reserves in East Asia, is located in the mouth of the Yangtze Estuary and is an important habitat for migratory birds. The Dongtan wetlands were listed in the Chinese Protected Wetlands in 1992, and were designated as internationally important under the Ramsar Wetlands Convention in 2001 and as a national nature reserve in 2005. By their very nature and location, the estuarine and coastal habitats are dynamic and their biodiversity conservation and management relies on up-to-date spatial information. By establishing qualitative and quantitative relationships between bird populations and key habitat factors such as elevation, land cover type, tidal creek density and macrophytobenthos biomass, we developed an object-oriented image approach, in conjunction with Geographical Information Systems and the data from current field surveys, to analyze and assess the habitat suitability for the main types of birds, namely Anatidae, Charadriidae, Ardeidae and Laridae, at the reserve. The results from this study showed that about 40% of the total area of the Dongtan Reserve contained suitable habitats for these four bird families. The Scirpus mariqueter zone, mudflat zone, and tidal creeks were the most important habitats for these birds. This study indicated the potential of this approach for objective and effective evaluation of the species habitat suitability in a dynamic estuarine and coastal area. The implications of the results as a tool for biodiversity conservation, wetland conservation, and ecosystem management are discussed.  相似文献   

节制对黄河水资源的过度索取,恢复黄河生态良性维持     

庞家珍  杨凤栋 《海洋湖沼通报》2008,(1):163-168

黄河下游属于过度开发的河流.长期以来。重视经济社会效益,而较为轻视环境和生态效益;上世纪80～90年代,下游出现连年断流及"二级悬河"两个突出问题。过量引黄,引黄总水量大大超过母亲河的承受能力,生产用水与社会用水大量挤占冲沙用水及生态用水,是上述问题形成的直接原因。为了维持黄河健康生命,保持河流永续利用,根本对策是在全流域建设高效、节水、防污型社会。节制社会经济用水;变粗放灌溉为科学灌溉;工业广用循环水;城市绿化及冲洗采用中水。制止对水质的污染。我们认为恢复黄河生态良性维持应包括三方面的指标:(1)下游排洪主槽通过调水调沙逐步恢复到6000m~3/s的过洪能力;(2)河水污染程度应稀释和降解到至少达到国家Ⅲ类水标准;(3)保证湿地及河、海、空中生物的良性生长环境。只要全流域以科学发展观为统领,实现人与河流和谐发展,经过10～20年的努力,上述目标是可以达到的。  相似文献   

中国遗产保护中地质公园面临的挑战     

王连勇 《地理学报(英文版)》2007,17(2):187-196

The author selects a thorny issue of doubled designations that bother policy-makers, professional planners and managers in the field of conservation for protected areas. The analyzed case study areas cover 5 National Geoparks of China in Sichuan Province, 18 UNESCO Global Geoparks in China, and 219 World Heritage sites in China and 8 European nations. Through analysis and synthesis, the author concludes that doubled designation, which also leads to unbalanced park distribution, is particularly prevalent in China other than in Europe. Therefore, on-site management agencies and related governments in China should carefully translate the doubled designations into responsibilities and harmonious partnerships between all stakeholders in order to enhance the management effectiveness and avoid paper park phenomenon.  相似文献   

Changes in streamflow regimes and their responses to different soil and water conservation measures in the Loess Plateau watersheds,China     

Shuyu Zhang  Guangju Zhao  Xingmin Mu  Peng Tian  Peng Gao  Wenyi Sun 《水文研究》2021,35(10):e14401

Investigating the changes in streamflow regimes in response to various influencing factors contributes to our understanding of the mechanisms of hydrological processes in different watersheds and to water resource management strategies. This study examined streamflow regime changes by applying the indicators of hydrologic alteration method and eco-flow metrics to daily runoff data (1965–2016) from the Sandu, Hulu and Dali Rivers on the Chinese Loess Plateau, and then determined their responses to terracing, afforestation and damming. The Budyko water balance equation and the double mass curve method were used to separate the impacts of climate change and human activities on the mean discharge changes. The results showed that the terraced and dammed watersheds exhibited significant decreases in annual runoff. All hydrologic metrics indicated that the highest degree of hydrologic alteration was in the Sandu River watershed (terraced), where the monthly and extreme flows reduced significantly. In contrast, the annual eco-deficit increased significantly, indicating the highest reduction in streamflow among the three watersheds. The regulation of dams and reservoirs in the Dali River watershed has altered the flow regime, and obvious decreases in the maximum flow and slight increases in the minimum flow and baseflow indices were observed. In the Hulu River watershed (afforested), the monthly flow and extreme flows decreased slightly and were categorized as low-degree alteration, indicating that the long-term delayed effects of afforestation on hydrological processes. The magnitude of the eco-flow metrics varied with the alteration of annual precipitation. Climate change contributed 67.47% to the runoff reduction in the Hulu River watershed, while human activities played predominant roles in reducing runoff in the Sandu and Dali River watersheds. The findings revealed distinct patterns and causes of streamflow regime alteration due to different conservation measures, emphasizing the need to optimize the spatial allocation of measures to control soil erosion and utilize water resources on the Loess Plateau.  相似文献   

Improving watershed management practices in humid regions          下载免费PDF全文

Fasikaw A. Zimale  Seifu A. Tilahun  Tigist Y. Tebebu  Christian D. Guzman  Linh Hoang  Elliot M. Schneiderman  Eddy J. Langendoen  Tammo S. Steenhuis 《水文研究》2017,31(18):3294-3301

In many parts of the world, watershed management practices have been extremely effective. However, implementation of soil and water conservation technologies in the humid African highlands, while beneficial in the short term, were remarkably unsuccessful in the long term. Insights from community knowledge perspectives have revealed that alternative methods are needed. Although conservation practices are designed to conserve water in semi‐arid areas, safely draining excess water is needed in humid areas. The objective of this paper is to review current watershed management approaches used in humid regions as exemplified by those used in Ethiopian highlands and then based on these findings propose more effective practices. Although current government sponsored practices primarily protect the hillsides, direct run‐off is generated from areas that become saturated on valley bottoms near rivers and on specific parts of the hillsides with degraded soils (or with highly permeable surface soils) and with perched water tables on slowly permeable horizons at shallow depths. In these areas, direct run‐off is increasing with deforestation and the soil degradation, demanding additional drainage ways that evolve in the form of gullies. Therefore, watershed management interventions for erosion control should prioritize revegetation of degraded areas, increasing sustainable infiltration, and rehabilitating gullies situated at saturated bottomlands.  相似文献   

Social and ecological effectiveness of large marine protected areas     

《Global Environmental Change》2017

Large marine protected areas are increasingly being established to meet global conservation targets and promote sustainable use of resources. Although the factors affecting the performance of small-scale marine protected areas are relatively well studied, there is no such body of knowledge for large marine protected areas. We conducted a global meta-analysis to systematically investigate social, ecological, and governance characteristics of successful large marine protected areas with respect to several social and ecological outcomes. We included all large (>10,000 km²), implemented (>5 years of active management) marine protected areas that had sufficient data for analysis, for a total of twelve cases. We used the Social-Ecological Systems Meta-Analysis Database, and a consistent protocol for using secondary data and key informant interviews, to code proxies for fisheries, ecosystem health, and the wellbeing of user groups (mainly fishers). We tested four sets of hypotheses derived from the literature on small-scale marine protected areas and common-pool resources: (i) the attributes of species and ecosystems to be managed in the marine protected area, (ii) adherence to principles for designing small-scale marine protected areas, (iii) adherence to the design principles for common-pool resource management, and (iv) stakeholder participation. We found varying levels of support for these hypotheses. Improved fisheries were associated with older marine protected areas, and higher levels of enforcement. Declining fisheries were associated with several ecological and economic factors, including low productivity, high mobility, and high market value. High levels of participation were correlated with improvements in wellbeing and ecosystem health trends. Overall, this study constitutes an important first step in identifying factors affecting social wellbeing and ecological performance of large marine protected areas.  相似文献