Tropical aquaculture: Need for a strong research base     

Roger S. Pullin  Richard A. Neal 《Marine Policy》1984,8(3):217-228

The authors argue that tropical aquaculture could make a significant contribution to the world fish supply, but is hindered by the absence of an adequate research base. They outline the history of aquacultural research, analyse the problem of the lack of a sustained basic research programme for the development of tropical aquaculture, and propose solutions on the basis of successes in agricultural research.  相似文献   

Food habits and seasonal variation of stomach contents of tongue soleCynoglossus semilaevis (Günther) in the Bohai Sea     

Dou Shuozeng 《中国海洋湖沼学报》1993,11(1):89-96

Examination of the food habits and seasonal variation of the stomach contents of adult tongue sole,Cynoglossus semilaevis (Günther) taken in July 1982–July 1983 from Laizhou Bay and the Huanghe River estuary of the Bohai Sea showed crustacea, bivalvia and small fishes comprised the main prey. Invertebrates such as polychaeta, cephalopoda, gastropoda, echinodermata and actiniaria were also intermittently found in them. They intensively fed all the year found (monthly feeding rate of over 80%). The main food items wereAlpheus japonica, Alpheus distinguendus. Oratosquilla oratoria, Eucrate crenata andCarcinoplax vestitus, etc. In summer and autumn, the portion of bivalvia such asCultellus attenuatus andMusculus senhousei increased steadily. From summer to winter, a stable proportion of small fishes such asRhinogobius pflaumi andSetipinna taty was in the diet. Contribution No. 1637 from the Institute of Oceanology, Academia Sinica.  相似文献   

THE FARMLAND CONVERSION DEBATE: NALS AND BEYOND*     

Rutherford H. Platt 《The Professional geographer》1985,37(4):433-442

The need to protect high quality agricultural land through public policies and programs at various levels of government has been debated in the U.S. for at least three decades. This article reviews the evolution of the debate before 1979, the ill-fated attempt of the National Agricultural Lands Study (NALS) (1979–1981) to resolve the debate, and the current status of the land conversion issue. Articulation of the issue has been impeded by confusion of objectives, semantic problems, unreliability of land conversion data, and excess capacity in the American farm economy. Land conversion estimates published in 1977 by the Soil Conservation Service and relied upon by NALS have proven to be misleading in light of the 1982 National Resources Inventory. State and local programs to discourage farmland conversion are justifiable in terms of land use planning objectives, maintenance of a viable local farm economy, and avoidance of undue reliance upon marginal lands requiring costly technical inputs.  相似文献   

The effects of prolonged aquatic macrophyte senescence on the biology of the dominant fish species in a southern African coastal lake     

A.K. Whitfield 《Estuarine, Coastal and Shelf Science》1984,18(3):315-329

The littoral zone of Swartvlei, an estuarine lake on the southern Cape coast, was characterized by extensive beds of submerged aquatic macrophytes. May 1979 marked the beginning of a regression phase which lasted more than three years. The senescence of the Potamogeton pectinatus and charophyte beds resulted in a 60% decline in primary production, a 74% slump in littoral invertebrate biomass and a 54% decline in the abundance of the fishes Monodactylus falciformis (Lacepede) and Rhabdosargus holubi (Steindachner) associated with the macrophytes. Gravimetric and calorific analyses of their food revealed that invertebrates and filamentous algae from the littoral zone were of major importance. The two fish species consumed approximately 2% of the primary production during the Potamogeton canopy phase and 3% during the Potamogeton senescent phase. Invertebrate consumption declined from 33 mg m^?2 day^?1 during the canopy phase to 8 mg m^?2 day^?1 during the senescent phase. The disappearance of the Potamogeton and charophyte beds also resulted in a decrease in the condition of both species but the effect was indirect and related mainly to the collapse of invertebrate stocks associated with the plants.  相似文献   

全球变化对中国粮食安全的影响分析   总被引：29，自引：6，他引：29  

王铮  郑一萍 《地理研究》2001,20(3):282-289

以斯德哥尔摩环境研究所(SEI)建立的粮食需求和供应模型为基础,同时采用Ds和Shaw建立的全球变化各因子对粮食需求和供给影响的模型对其变量进行修正,结合唐国平、李秀彬的结果,模拟计算了全球变化条件下,我国未来粮食需求量和产量。在分析中发现:受全球变化的影响,在保持人民消费水平持续增长的条件下我国未来粮食生产有可能不能满足需求增长的要求,存在7～8%的粮食缺口。但是,由于全球变化的各个因素都存在很大的不确定性,而且技术进步对增加粮食产量有很大促进作用。计算结果揭示,只要采取正确的措施来尽量减少全球变化带来的不利影响,危机是可以避免的  相似文献   

绿色食品产业开发的国际经验及我国的对策   总被引：4，自引：0，他引：4  

周旗  江富建 《世界地理研究》2002,11(3):32-36

在借鉴国外经验的基础上，本文根据我国国情和经济社会发展的需要，研究了绿色食品发展的产业定位和地域类型，并从区域发展的角度，探讨了我国绿色食品产业开发的原则和对策。  相似文献   

液动锤钻探技术实践及展望          下载免费PDF全文

王人杰 《探矿工程》1996,(4):11-13

利用泥浆泵驱动的液动潜孔锤钻探技术比回转钻探强化了碎过程，在复杂岩层中钻进减少岩堵塞，提高钻并笔直度。论述了阀式液动锤设计及评价的依据。提出了大陆科学钻探利用此技术的前景和建议。  相似文献   

FOOD SECURITY OF CHINA AND LESTER BROWN''S POINT OF VIEW     

Liu Yanhua Zhao Mingcha Sun Huinan Institute of Geography  CAS  Beijing People''s Republic of China 《地理学报(英文版)》1997,(4)

Ｉ.ＴｈｅＰｏｓｉｔｉｖｅＲｏｌｅｏｆＢｒｏｗｎ’ｓＡｒｔｉｃｌｅＡｓａｆｏｒｅｉｇｎｓｃｈｏｌａｒ,Ｍｒ.Ｌ.Ｂｒｏｗｎｈａｓｋｎｏｗｎａｓｅｒｉｅｓｏｆｄａｔａａｎｄｍａｔｅｒｉａｌｓｏｎｐｏｐｕｌａｔｉｏｎ,ｆｏｏｄｐｒｏｄｕｃｔｉｖｉｔｙａｎｄｒｅｌｅｖａｎｔｆａｃｔｏｒｓｏｆＣｈｉｎａ,ｈａｄｍａｄｅｒａｔｈｅｒｄｅｅｐａｎａｌｙｓｉｓａｎｄｇｉｖｅｎａｆｏｒｅｃａｓｔｏｆｆｏｏｄｓｅｃｕｒｉｔｙｏｆＣｈｉｎａ.Ｈｅｈａｓｓｈｏｗｎｔｈｅｐｏｓｓｉｂｌｅｓｅｒｉｏｕｓｓｅｑｕｅｎｃｅｉｎｆｏ…  相似文献   

海洋浮游细菌的生态学研究   总被引：23，自引：2，他引：23  

肖天 《地球科学进展》2001,16(1):60-64

海洋浮游细菌在海洋生态系统中的重要作用随着对其生物量和生产力的深入研究而得到了充分肯定。以浮游细菌为核心的微食物环研究的开展，也显示出微食物环在海洋生态系统动力学过程中有不可替代的作用，是主食物链的重要补充，特别是在贫营养的大洋生态系统中。在不同水 层和特殊环境中对海洋浮游细菌的研究结果表明其研究潜力巨大。就国内在这方面的研究现状和需进一步研究的内容进行了阐述。  相似文献   

Ichthyoplankton distribution and plankton production related to the shelf break front at the Aviles Canyon     

Gonzalez-Quiros  R; Cabal  J; Alvarez-Marques  F; Isla  A 《ICES Journal of Marine Science》2003,60(2):198-210

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