Field experiments on the role of epibenthic predators in determining prey densities in an estuarine mudflat     

J.M. Gee  R.M. Warwick  J.T. Davey  C.L. George 《Estuarine, Coastal and Shelf Science》1985,21(3):429-448

A series of caging experiments was performed on an estuarine mudflat at three seasons of the year, in which Carcinus maenas L. and Pomatoschistus microps (Kroyer) were either excluded from, or allowed to prey upon, the benthos in order to determine to what extent infaunal abundance and mortality was a result of predation by epibenthic predators.The difficulties of conducting and interpreting the results of such experiments are recognized. The benthic macrofauna of this mudflat is dominated numerically by small annelids and there is evidence that adult C. maenas can cause significant increases in the oligochaete component of this assemblage, probably as a result of disturbance caused by its burrowing activity. Juvenile C. maenas on the other hand significantly reduced the abundance of small annelids, particularly the dominant polychaete Manayunkia aestuarina (Bourne) and could be responsible for year-to-year variations in abundance of this species. The role of fish predators (in this case P. microps) is more problematical but it is suggested that in the densities at which they occur naturally on the mudflat they have little direct effect on the abundance of prey species. There is no evidence that seasonal mortality of small annelids is reduced in the absence of predation and this is taken to indicate that not all mortality is due to epibenthic predation. Certain changes in relative abundance of the component species of the harpacticoid copepod community were discerned but it is suggested that the plasticity of their reproductive potential is such that the effect of predation on the group as a whole is usually masked.  相似文献   

FATTY ACIDS PROFILE IN A HIGH CELL DENSITY CULTURE OF ARACHIDONIC ACID-RICH PARIETOCHLORIS INCISA （TREBOUXIOPHYCEAE, CHLOROPHYTA） EXPOSED TO HIGH PFD   总被引：1，自引：0，他引：1  

Liu Jian-guo  Zvi Cohen  Amos Richmond 《中国海洋湖沼学报》2002,20(2):149-156

The changes in arachidonic acid (AA) and fatty acids profiles along the growth curve ofParietochloris incisa, a coccoid snow green alga, were studied in a 2.8 cm light-path flat photobiorcactor, exposed to strong photon flux density [PFD, 2400 μEmol/(m²·s)]. Sixteen fatty acids were identified by gas chromatography showing that AA was the dominant fatty acid (33%–41%) followed by linoleic acid (17%–21%). AA content was closely investigated with respect to total fatty acids (TFA), ash free dry weight (AFDW) of cell mass as well as total culture content. These parameters were influenced significantly in a similar manner by culture growth phase, i.e., slightly decreasing in the lag period, gradually increasing in the logarithmic phase, becoming maximal at the early stationary phase, starting to decrease at the late stationary phase, sharply dropping at the decline phase. The increase in AA per culture volume during the logarithmic phase was not only associated with the increase in AFDW but also connected with a corresponding increase in AA/TFA, TFA/AFDW as well as AA/AFDW. The sharp decrease in AA content of the culture during the decline phase was mainly due to the decrease in AA/TFA, TFA/AFDW and AA/AFDW, although AFDW declined only a small extent. Maximal AA concentration, obtained at the early stationary phase, was 900 mg/L culture volume, and the average daily net increase of AA during 9 days logarithmic growth was 1.7 g/(m²·day). Therefore, harvesting prior to the decline phase in a batch culture, or at steady state in continuous culture mode seems best for high AA production. The latter possibility was also further confirmed by continuous culture with 5 gradients of harvesting rate. Contribution No. 4138 from the Institute of Oceanology, Chinese Academy of Sciences. Project 39970575 supported by NSFC and A/2786-2 supported by International Foundation for Sciences (IFS).  相似文献   

历史时期官吏在海南开疆文化发展中的作用   总被引：4，自引：1，他引：4  

朱竑  薛德升  曹小曙 《地理科学》2002,22(2):144-149

以海南岛开疆文化的发展为例，探讨了历史时期各级官员在海南岛文化发展中的作用。指出我国历代的朝廷官员为特殊的选拔机制，从而较一般人更有能力在边疆文化发展呼社会进步中发挥主要作用。文章最后指出，现今我国的西部大开发中，从经济发达地区选派干部到西部挂职锻炼，以及从经济落后地区选派优秀干部到经济发达地区挂职学习是新时期的两种行之有效的开疆举措。  相似文献   

Political culture: a typology grounded on Cultural Theory     

VirginieD. Mamadouh 《GeoJournal》1997,43(1):17-25

Political culture is an attractive concept to characterize the specific preferences regarding politics in different political communities. However, it is a blurred concept because of the confusion between patterns of individual values and collective culture at the one hand, and the disputable separation between orientations and practices at the other hand. This contribution explores the potential of Cultural Theory, also called the Theory of Sociocultural Viability, to analyze political culture. This theory postulates the existence of four viable ways of life, which are patterns of social interactions and rationalizations reinforcing each other. Each way of life offers a partial explanation of reality and therefore reaches out for cultural allies who can compensate for its weakness. Such an alliance, generally between two ways of life, can be quite stable and therefore determines to a large degree the nature and the stability of the political institutions of a country. The political culture of a political community can be characterized by the proportion of adherents of each way of life (its regime), and by the predominant alliance of two ways of life.  相似文献   

论绿色文明与民族边疆山区农村经济的可持续发展——以云南省西双版纳为例   总被引：2，自引：0，他引：2  

张佩芳  吕星  周钜乾 《热带地理》2001,21(1):71-75

云南边疆、山区、少数民族地区，寻求森林生态系统与经济系统的协调发展，寻求攀元民族文化下的山区资源利用可持续发展战略，是加强民族团结，实现各民族共同繁荣富裕、区域经济发展的关键。文中运用高新技术遥感（RS）、地理信息系统（GIS），结合村寨社区调查，对云南西双版纳6种主体少数民族传统用地习俗、土地结构变迁及农村经济发展等方面进行了分析研究评价，在此基础上初步探讨山区边疆少数民族地区传统文化与农村经济持续发展的关系，提出看法及供商榷。  相似文献   

基于“鱼文化”的清远白庙渔村旅游区规划研究   总被引：2，自引：0，他引：2  

李凡  黄耀丽  杨俭波 《热带地理》2001,21(3):242-245

鱼文化是中国传统文化的组成部分，文中分析了“鱼文化”的特点，在进行清远白庙渔村旅游规划过程中，通过对白庙旅游资源的分析，提出将“鱼文化”作为白庙旅游区规划的文化脉络，应用旅游文化分析在规划中的作用，构建基于“鱼文化”的独具特色的旅游文化空间结构。  相似文献   

Just a train-ride away, but still worlds apart: Prospects for the Øresund region as a binational city     

Gregg Bucken-Knapp 《GeoJournal》2001,54(1):51-60

This article considers whether the cities of Copenhagen, Denmark and Malmö, Sweden, recently joined by the Øresund bridge, ought to be considered as one binational city. Working from the assumption that the project of constructing this binational city is a top-down endeavor whose success ultimately rests on the degree of support it receives from regional inhabitants, I focus on public opinion survey data collected one year after the opening of the bridge. Analysis shows that there are sharp national differences in the amount of support for the construction of a binational greater metropolitan region. I discuss how these differences may lead to an asymmetrical development for the emerging binational city, with Malmö eclipsed by the Danish capital Copenhagen, as well as how the heavily multi-cultural population of Malmö can impact Danish-Swedish cooperation on the Øresund.  相似文献   

Occurrence of Spadella cephaloptera During One Year at Ischia Island (Gulf of Naples)     

T. Goto 《Marine Ecology》1995,16(3):251-258

Abstract. The life cycle of the benthic arrowworm, Spadella cephaloptera , which inhabits the Posidonia meadow at Ischia (Gulf of Naples, Italy), was examined by a one-year systematic sampling survey and by laboratory culture. The seasonal fluctuations in abundance and the reproductive characteristics indicate that there were two generations of S. cephaloptera in one year; these generations have a different life span. The habitat of S. cephaloptera depends on the growth of the Posidonia meadow; the influence of different factors on the S. cephaloptera population, especially of the Posidonia vagile fauna, is discussed.  相似文献   

文蛤外套膜组织与细胞培养   总被引：3，自引：0，他引：3       下载免费PDF全文

陈颉  许璞  沈爱国  万夕和  刘海鸥  沈辉  杨家新 《海洋科学》2007,31(6):60-64

以文蛤(Meretrix meretrix Linnaeus)外套膜为材料,采用改良的M199培养基,在不同温度和盐平衡条件下进行组织与细胞培养。培养结果显示,24 h左右外套膜组织边缘有细胞爬出,48 h后开始形成单层新生细胞,并发展为生长晕,7~10 d细胞基本长满培养瓶底。细胞培养可持续30~35 d。作者还描述了培养过程中出现的3种不同形态特征的细胞,并对37℃培养条件下细胞的生长及分裂特征作了描述与讨论。  相似文献   

苜蓿组织培养体细胞胚发生的细胞学观察   总被引：1，自引：0，他引：1  

宫相忠  黄健 《中国海洋大学学报(自然科学版)》1997,(4)

苜蓿无菌苗下胚轴在含２ｍｇ／Ｌ２．４－Ｄ和０．５ｍｇ／Ｌ６ＢＡ的ＭＳ培养基中诱导出愈伤组织，愈伤组织在含有３ｍｇ／ＬＮＡＡ和１．５ｍｇ／ＬＫＴ的ＳＨ培养基中形成胚性愈伤组织，并伴随有体细胞胚的发生。显微观察表明：体细胞胚起源于单个的胚性细胞，它既能在愈伤组织内部发生，又可在其表面发生。体细胞胚经过球形、心形、鱼雷形及子叶胚各阶段可形成再生植株，这为在细胞水平上对苜蓿进行遗传操作及苜蓿品种的改良成为可能。  相似文献