放养密度对大杂交鲟生长性能的影响及生理应答机制

为探讨放养密度对鱼类生长及生理应答机制的影响规律和作用,作者以大规格大杂交鲟(达氏鳇(Huso dauricus)♀×施氏鲟(Acipenser schrenckii)♂)为实验材料,研究了平均初始体质量约为243 g/尾,放养密度分别为6(SD1组)、9(SD2组)、12(SD3组)、15 kg/m3(SD4组)条件下,不同放养密度处理70 d后的实验鱼生长性能变化及生理应答机制。结果显示,放养密度对大杂交鲟肥满度影响不显著,SD2组鱼类具有最大的特定生长率和生长效率,随着放养密度增加,日增质量显著降低(P0.05),特定生长率和生长效率下降。测定了血液甲状腺素(T4)、三碘甲腺原氨酸(T3)和皮质醇水平变化,发现放养密度能引起大杂交鲟3个血液生理指标发生显著改变;随着养殖时间推移,T3和皮质醇浓度显著升高,T4浓度显著下降(P0.05)。这些结果说明神经内分泌活动的变化引起大杂交鲟血液生理指标变化,进而影响实验鱼生长性能。因此,在该养殖条件下推荐的养殖密度为9 kg/m3。     

Density‐Dependent Effects in Jehlius cirratus (Darwin, 1854) (Cirripedia: Chthamalidae) under Different Growth Conditions

Abstract. We analyse the effects of crowding (‘hummocking’) on the growth, reproduction and mortality of the chthamaloid barnacle Jehlius cirratus ( Darwin, 1854 ) on the coast of Chile. Recruitment intensity, ranging from solitary individuals to dense groups, generates different growth conditions. Density‐dependent effects are reflected in the shape, growth parameters, fecundity, sexual maturity and mortality of solitary and crowded specimens. The skewing of size distribution during growth was not significant at the beginning of the growth period, irrespective of initial density. Nevertheless, skewness in size increased with time, both at high and low densities, indicating that the dominance and suppression exerted by larger specimens over smaller ones generate a density‐dependent effect on size during growth. Mortality was greatest when high‐density recruitment occurred immediately before the period when water temperature and food quantity are highest (spring), when it is assumed that growth is greatest; this seasonal effect was not detected at lower levels of recruitment density. Similarly, no differences in mortality were detected between recruitment densities during the period when temperatures are lowest (autumn) and growth is probably slower. In the middle‐high intertidal zone, where J. cirratus co‐exists with Notochthamalus scabrosus ( Darwin, 1854 ), the proportion of dead J. cirratus specimens was directly related both to the relative abundance of N. scabrosus and the total barnacle density. Although the mortality of J. cirratus was density dependent, the increase in the number of N. scabrosus towards the lower section of the middle intertidal zone could have a greater effect on J. cirratus mortality than intra‐specific competition.     

BOOK REVIEWS

Book Reviewed in this article: Portable Utopia: Glasgow and the United States 1820–1920. Bernard Aspinwall. Studies in Russian Historical Geography. James H. Bater and R. A. French, eds. Water and Sanitation: Economic and Sociological Perspectives. Peter G. Bourne, ed. Green Politics. Fritjof Capra and Charlene Spretnak. The Southern Cone: Realities of the Authoritarian State. César N. Caviedes. Women in Third World Development. Sue Ellen Charlton. Land Management: New Directions. David Chiddick and Alan Millington, eds. Geography and Ethnic Pluralism. Colin Clarke, David Ley, Ceri Peach, eds. Geomorphological Hazards in Los Angeles. R. U. Cooke. Regional Impacts of United States-Mexico Economic Relations. Alfonso Corona and Lay James Gibson. eds. Patterns of Jobs and Geographic Mobility. Torvald Gerger. Cities and Sickness: Health Care in Urban America. Ann Lennarson Greer and Scott Greer, eds. Neighborhoods: Their Place in Urban Life. Howard W. Hallman. Development and the Rural-Urban Divide. John Harriss and Mick Moore, eds. Patterns of Undocumented Migration: Mexico and the United States. Richard C. Jones, ed. Central Place Theory. Leslie J. King. The Geography of Western Europe: A Socio-economic Survey. Paul L. Knox. Regions and Resources: Strategies for Development. David T. Krisge, Daniel A. Seiver, Oliver S. Goldsmith and Michael J. Scott. Geography of Crowding and Human Response. A Study of Ahmedabad City. K. M. Kulkarni. Haciendo Pueblo. The Development of a Guadalajaran Suburb. Kathleen Logan. The Imperial Lion: Human Dimensions of Wildlife Management in Central Africa. Stewart A. Marks. Water in the Hispanic Southwest: A Social and Legal History, 1550–1850. Michael C. Meyer. Imlil: A Moroccan Mountain Community in Change. James A. Miller. Tourism in Canada: Selected Issues and Options. Peter E. Murphy, ed. David Harvey's Geography. John L. Paterson. Raster Scanning, Processing and Plotting of Cartographic Documents. Donna J. Peuquet and A. Raymond Boyle. The USSR and the Muslim World: Issues in Domestic and Foreign Policy. Yaacov Ro'i, ed. Environmental Perception and Behavior: An Inventory and Prospect. Thomas F. Saarinen, David Seamon, and James L. Sell. Incised channels, Morphology, Dynamics, and Control. Stanley A. Schumm, Michael D. Harvey, and Chester C. Watson. The Gap Between Rich and Poor: Contending Perspectives on the Political Economy of Development. Mitchell A. Seligson, ed. Twentieth-Century Richmond. Planning, Politics and Race. Christopher Silver. Land Conservation and Development: Examples of Land-Use Planning Projects and Programs. F. R. Steiner and H. N. van Lier, eds. Biogeography: Recent Advances and Future Directions. J. A. Taylor, ed. Late Quaternary Environments of the Soviet Union. A. A. Velichko, ed. H. E. Wright, Jr. and C. W. Barnosky, eds.     

黑龙江省能源资源开发的经济效应分析

在分析黑龙江省经济发展的周期波动与能源资源开发增长在时间序列上的耦合关系的基础上,引入资源“诅咒系数”理论来测定资源开发对区域经济发展的诅咒现象出现时间、发展走向、不同年份诅咒强度,并通过诅咒的传导机制研究剖析诅咒效应长期作用的原因。结果表明:黑龙江省资源开发与经济发展轨迹之间存在着良好的耦合关系,资源开发长期上看对经济发展存在着严重的诅咒效应;近年来资源开发的诅咒程度虽然呈持续下降态势,但诅咒的延迟性致使诅咒效应仍阻碍着黑龙江省经济的发展并还会持续较长一段时间。诅咒效应形成与财政开支不断增大,能源开发投入导致科技、教育财政支出大幅度减少存在着密切的关联,也与资源对经济发展路径锁定性密切相关。     

游客拥挤的生成、差异与影响:综述与展望

随着旅游活动大众化,游客拥挤愈发常态化。全面梳理游客拥挤的研究进展对于强化游客管理、促进旅游业高质量发展具有重要意义。从游客拥挤的内涵、测度、生成机制、影响因素、作用效果等多个角度进行文献梳理,研究发现:1)游客拥挤是游客对所处游览环境的负面评价,是对空间拥挤和人群拥挤的消极感知,刺激超载理论、社会干预理论及期望理论对游客拥挤的生成具有较好的解释效应;2)游客拥挤感存在明显差异,该差异主要来源于个体、空间场景及人群环境等因素,社会认同理论、唤醒理论、规范理论及曼宁理论能够有效解释游客拥挤感知差异的生成;3)游客拥挤易对游客情感、旅游满意度与忠诚度产生负面影响,易引发产品转换、合理化、置换等调试行为。今后研究可结合时空情境,关注游客拥挤的差异化测量、识别影响游客拥挤的关键因素以及探明游客拥挤的多元影响,如游客拥挤对景区管理、目的地规划布局、旅游可持续发展的影响。     

本世纪以来台湾及邻近海域的强震活动特征

本文分析了台湾及其邻近海域M≥7级地震的时空演变特点，并对其进行了分区讨论，发现该区各活动时段的地震活动有集丛分布的特征，该区东部地区与下扬子地区，西部地区与闽东地区地震有一定的呼应关系，并对今后几年地震活动趋势作出了估计。     

Tourist Carrying Capacity Measures: Crowding Syndrome in the Caribbean

International tourism is increasing at an unprecedented rate. Understanding the variety of national and local impacts of this increase is of importance to a growing number of governments. Butler's resort cycle model (1974, 1980, 1991) provides for several long‐term possibilities as to the relationship between crowding and growth. McElroy, de Albuquerque, and Dioguardi (1993) focus on one of those possibilities. Specifically, using their penetration ratio, they predict that as tourist crowding continues for a group of Caribbean islands, the appeal of these islands decreases in the eyes of potential tourists and that, as time increases, the growth rate of the affected islands, actually decreases. Our article indicates that such a simple, straight‐line relationship between increased crowding and a decrease in the rate of change may not be inevitable; indeed, diseconomies of scale may be avoided. The use of a curvilinear regression function reveals how both positive and negative scale economies existed in the Caribbean during the years 1992 through 1996.     

山岳型景区特殊时段旅游拥挤特征及调控模式——以黄山风景区为例

世界遗产地空间潮汐式旅游拥挤问题相当普遍且日益凸显,已成为旅游地理学研究的前沿领域。以黄山风景区为例,基于旅游拥挤多维内涵,构建物理拥挤和心理拥挤二维指标,结合游客访谈,分析了景区的拥挤特征及影响因素。研究发现：① 不同地点物理拥挤与心理拥挤呈现不同的表征关系;② 由于游客目标与需求不同,在资源吸引力、服务设施和空间特征等因素的触发下,导致高山比低山物理拥挤度强,线性空间比点状空间的拥挤感知强烈,这是景区发展不均衡且与游客互动缺乏动态性、主动性和创新性的表现。最后,基于特殊时段和特殊空间背景下多样性和动态性的空间-行为互动模式,提出“奶酪型”“小丑型”“泄洪型”和“花瓶型”四类调控类型。     

1800年以来长江中下游地震区中强地震集丛分布和迁移特征

本文对长江中下游地震区1800年以来中强地震活动进行了分区讨论,总结其活动规律,类比外推对该区M≥5.5级地震活动趋势作了估计。     

Distribution,Population Structure, ­Population Biomass and Morphological Characteristics of the Tunicate Pyura stoloniferain the Bay of Antofagasta,Chile

Abstract. The present study analyzes the distribution, population structure, population biomass and morphological characteristics of the intertidal tunicate Pyura stolonifera (Heller, 1878) in the Bay of Antofagasta, Chile, where the species shows a reduced geographical range extending around 60 – 70 km. Three sites along its distribution were studied. At the central site the tunicate presents the widest intertidal belts, reaching nearly 11 m (the mid‐intertidal‐Pyura‐zone shows the higher percent cover). Population dry biomass here averaged up to 20.45 kg·m^–2, representing one of the highest intertidal specific biomasses reported in the literature. Lower values occur towards the borders of its distribution. Population densities were over 1800 indiv.·m^–2 at mid‐intertidal‐Pyura‐belts. Crowding and competition potentially affect morphological characteristics and the energy/tissue allocation along the intertidal and geographical gradient of P. stolonifera.