Coral bleaching on high-latitude marginal reefs at Sodwana Bay,South Africa     

Celliers L  Schleyer MH 《Marine pollution bulletin》2002,44(12):1380-1387

Coral bleaching, involving the expulsion of symbiotic zooxanthellae from the host cells, poses a major threat to coral reefs throughout their distributional range. The role of temperature in coral bleaching has been extensively investigated and is widely accepted. A bleaching event was observed on the marginal high-latitude reefs of South Africa located at Sodwana Bay during the summer months of 2000. This was associated with increased sea temperatures with high seasonal peaks in summer and increased radiation in exceptionally clear water. The bleaching was limited to Two-mile Reef and Nine-mile Reef at Sodwana Bay and affected <12% of the total living cover on Two-mile Reef. Montipora spp., Alveopora spongiosa and Acropora spp. were bleached, as well as some Alcyoniidae (Sinularia dura, Lobophytum depressum, L. patulum). A cyclical increase in sea temperature (with a period of 5–6 years) was recorded during 1998–2000 in addition to the regional temperature increase caused by the El Niño Southern Oscillation phenomenon. The mean sea temperature increased at a rate of 0.27 °C year⁻¹ from May 1994 to April 2000. High maximum temperatures were measured (>29 °C). The lowest mean monthly and the mean maximum monthly temperatures at which coral bleaching occurred were 27.5 and 28.8 °C, respectively, while the duration for which high temperatures occurred in 2000 was 67 days at 27.5 °C (4 days at 28.8 °C). Increased water clarity and radiation appeared to be a synergistic cause in the coral bleaching encountered at Sodwana Bay.  相似文献   

Transformation of a border region: dispersed agricultural communities in Brasov County, Romania     

Nicolae Muica  Lesley Roberts  David Turnock 《GeoJournal》1998,46(3):305-317

A most distinctive feature of the settlement pattern of the Brasov area is the extreme dispersal of mixed farming encountered in the western extreme of the county to the north and south of Zarnesti: the Bran and Poiana Marului areas. Here a system of peasant subsistence farming developed in a political borderland between the Habsburg and Ottoman Empires. Despite feudal pressures, the peasantry took all available opportunities to extend their independence including elaborate transhumance systems. And after seeing transfrontier commerce as a source of plunder, in the tradition of Balkan highway robbery within relatively unregulated spaces, the peasantry has profited through employment in factories, particularly during the communist period. However, the current recession in manufacturing is throwing the rural population back on limited land resources. Although farming assumes an important subsistence role which contributes to stability, the long-term survival of these communities will depend on new sources of income. Rural tourism has considerable potential and a promising start has been made in Bran. There are, however, constraints on the further development of the business and great attention will have to be given to the conservation of the environment in both the Bucegi Mountains and the Piatra Craiului where national park status is proposed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Preliminary studies on methane fluxes in Hainan mangrove communities     

卢昌义  黄玉山  谭凤仪  叶勇  崔胜辉  林鹏 《中国海洋湖沼学报》1998,16(1):64-71

INTRODUCTIONChrbondioxideandInehanearethetwomostabundantabosphericcarbonspedes.Methane'sconcenhati0nintheboposphereinonsesO.7-l.l%peryearraasmussenandKhaili,l98l,BlakeandRowand,l988,Scheeetal.,l989).Ihauseofmethne'sforpaCtontheearth'sclirnateandthechernistryoftheatInosphere,thebudgetofabosphericmethanehasmivedconsiderableattchti0n.Wetlandsareestirnataltobeoneofthelamptsoimofabosphericmethane,aocountingforab0ut4O%to5O%0ftheglobalInehanesoonannually(Cforneand0reInland,l988,WhitingandC…  相似文献   

Long-term benthic population changes (1920–1930s-present) in the Barents and Kara Seas     

O. A. Kiyko  V. B. Pogrebov 《Marine pollution bulletin》1997,35(7-12):322-332

Bottom sediment was analysed, via grab, trawl and underwater photography in 1991–1992 in the Barents, White, Kara, Norwegian and Greenland Seas, and the large scale features of macrobenthos distribution are described. The maps of alpha-diversity, biomass and trophic zone distribution on the investigated shelf are presented. Statistical assessment of the bottom community structure changes during the last 60–70 years for the Barents Sea area is presented. It is shown that on regional and transregional levels the researched communities are of natural undisturbed character and that the revealed changes may be both the result of natural processes or sampling errors. Local disturbances of benthos composition and structure, supposedly caused by man, are found to be rare not far from the Novaya Zemlya and Murman coasts.  相似文献   

Soil–vegetation relationships in a coastal desert plain of southern Sinai, Egypt     

Monier M. Abd El-Ghani  Wafaa M. Amer 《Journal of Arid Environments》2003,55(4):607-628

The present study provides an analysis of soil, vegetation types as well as structure and species distribution in 19 sites in El-Qaa plain along the Gulf of Suez (south Sinai, Egypt), and focuses on the environmental factors that control the species distribution. A total of 203 species belonging to 39 families of the vascular plants are recorded. Asteraceae, Fabaceae, Chenopodiaceae and Poaceae are the largest families. Grasses constitute only 9% of the recorded species, while the woody perennials (shrubs and sub-shrubs) are highly dominated (46%). Therophytes and chamaephytes are the most frequent, denoting a typical desert life-form spectrum. Floristic composition in the different geomorphologic landscape units showed differences in species richness. The highest mean species richness of 19.7±1.7 is recorded in the wadi channels. The lowest species richness values are recorded in the coastal shore and playas (6.0±1.4) and in the alluvial fans (mean of 8.4±1.6 species). Chorological analysis revealed that 46% of the studied species are uniregional, being native to the Saharo-Arabian region. On the other hand, about 50% of the recorded species are biregional and pluriregional, extending their distribution all over the Saharo-Arabian, Sudano-Zambezian, Irano-Turanian and Mediterranean regions. Classification of the vegetation is analysed using two-way indicator species analysis (TWINSPAN) techniques resulted in the recognition of five vegetation groups, each of definite vegetation and soil characters, and could be linked to a specific geomorphologic unit. Capparis spinosa var. spinosa occupied the terraces, Cornulaca monacantha, Convolvulus lanatus and Deverra tortuosa inhabited the alluvial plains, Launaea nudicaulis and Artemisia judaica characterized the wadi channels, Acacia tortilis subsp. raddiana and Leptadenia pyrotechnica characterized the alluvial fans and Tamarix nilotica, Zygophyllum album and Nitraria retusa on the playas and the coastal shore. Ordination techniques as detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) are used to examine the relationship between the vegetation and studied soil parameters. Nine soil variables are included: electrical conductivity, pH, calcium carbonate, gypsum, organic matter, gravel, fine soil fractions and soil saturation percentage. Analysis with DCA gave results similar to CCA, suggesting that there is a relatively high correspondence between vegetation and soil factors. DCA axis 1 showed significant positive correlation with CaCO₃, pH, soil saturation and organic matter, and interpreted as a calcium carbonate—soil saturation gradient. DCA axis 2 showed significant correlation with pH, gypsum and electric conductivity, and interpreted as an electric conductivity—gypsum gradient. Application of CCA indicated that soil surface sediment, CaCO₃, soil saturation, pH and organic matter are the main operating edaphic gradients in the area. These gradients are related closely to the first three canonical axes, and accounted for 67% of the species–environment relationship among the sites.  相似文献   

Book Reviews     

《Singapore journal of tropical geography》2002,23(2):236-243

Books reviewed:
Maruja M.B. Asis, (ed.) The Philippines as Home: Settlers and Sojourners in the Country.
Hans Gooszen, A Demographic History of the Indonesian Archipelago, 1880–1942.
Karin Bras, Image-Building and Guiding on Lombok: The Social Construction of a Tourist Destination.
K.S. Chon, (ed.) Tourism in Southeast Asia: A New Direction.  相似文献   

基于电子地图的村镇社区地方病、传染病防治咨询系统的研究与设计     

高万林  于丽娜  段青玲  雷宏洲  陈昕  卢韬 《测绘软科学研究》2010,(3):11-15

村镇社区作为我国社会的基层组织,是社会生活最基本的环境载体,村镇社区对地方病、传染病防治工作的开展对城市社会医疗卫生工作的良性运行具有重要的影响。计算机、网络、数据库等技术的发展,为提高村镇社区地方病、传染病的防治管理水平提供了有效的途径。从村镇社区实际出发,设计了基于Java Applet的电子地图应用程序JAEMA,在此基础上,采用轻量级设计模式,综合运用Struts＋Spring＋Hibernate框架构建了村镇社区地方病、传染病防治咨询系统EIPCAS,为提高村镇社区地方病、传染病防治水平提供有效的技术支撑和决策支持。  相似文献   

新型城镇化背景下中国流动人口研究:议题与展望   总被引：13，自引：10，他引：3  

朱竑  张博  马凌 《地理科学》2019,39(1):1-11

研究通过4个议题（户籍与人口流动,循环流动、定居意愿及家庭策略,社会网络和移民社区,迁移、流动性和移民的日常生活）,回顾了近年来乡城人口迁移的研究。指出：户籍政策对移民在城市中的生计带来的影响将减弱,移民的住房及在城市的居住模式和居住空间、社会交往、生活方式、移民身份建构及生活空间的重构等将会成为新的关注点。新文化地理学中关于移民“微观化”“生活化”的研究应受到更多的重视。换言之,如何理解移民在个体层面的诉求和移民的日常生活,将会是未来流动性研究的重点。如何立足于国内移民地理研究的基础与发展机遇,批判性地与西方移民研究搭建对话空间和平台,结合当前中国崛起过程中所呈现的前所未有的全球化与城镇化契机,为世界移民研究积累和贡献“中国知识”,将成为未来这一领域学者研究的方向。  相似文献   

江湖阻隔背景下东部平原湖泊鱼类功能特征及多样性变化     

郑鹏  蒋小明  曹亮  王俊  姜卓群 《湖泊科学》2022,34(1):151-161

东部平原湖泊区是我国淡水湖泊最集中的地区,分布着我国的五大淡水湖等诸多湖泊.然而,江湖阻隔对该区域湖泊的生物多样性造成严重威胁.本文选取东部平原的9个湖泊,对江湖阻隔前后鱼类功能性状（3组分类性状和6个连续性状）和功能多样性指数的变化规律开展了研究.结果表明,9个湖泊的鱼类总物种数由江湖阻隔前的140种减少为江湖阻隔后的100种,平均物种数由79.6种减少到52.1种（减少34.4%）.江湖阻隔后鱼类群落的功能性状和功能多样性指数发生了显著变化,洄游性鱼类（包括河海洄游和江湖洄游）物种占比（由39.7%降至32.6%）和鱼食性物种占比（由31.1%降至25.2%）显著下降,而非洄游性物种占比（由60.3%升至67.5%）和浮游生物食性物种占比（由13.5%升至15.5%）显著上升.连续型性状中,平均营养级（由3.14降至3.10）显著下降、平均生长速率（由0.57 a^-1升至0.65 a^-1）显著上升.阻隔后的物种数（SR）、功能丰富度指数、功能离散度指数和功能分散指数显著低于阻隔前.本研究表明江湖阻隔后鱼类群落不仅物种丰富度下降,且功能性状趋向同质化（或单一化）发展,致使功能多样性下降.研究结果可为东部平原湖泊的渔业资源管理及湖区生态修复和保护提供重要的理论依据.  相似文献   

东南极普里兹湾陆架区大型底栖动物群落结构     

刘坤  林和山  何雪宝  黄雅琴  李众  林俊辉  牟剑锋  张舒怡  王建军  孙军 《海洋学报(英文版)》2020,39(2):38-48

To explore the spatial pattern of macrobenthic communities and their response to environmental factors in the Prydz Bay,samples were collected using a 0.25-m2 box corer at 10 stations from November 2012 to April 2013.A total of 50 species of macrobenthos belonging to 8 phyla and 33 families were identified,of which polychaetes(e.g.,Maldane sarsi)and sponges(e.g.,Halichondria sp.and Leucosolenia sp.)were the most prominent groups.The macrobenthos in study area were categorized into five functional groups based on the feeding type,and the detritivorous group represented by polychaetes showed the highest average abundance,while the planktophagous group represented by sponges showed the highest average biomass.Macrobenthos abundance(0–592 ind./m2)and biomass(0–1155.5 g/m2)in the Prydz Bay were relatively lower than those of other Antarctic shelf soft-bottom waters,although the compositions of the dominant species and functional feeding groups were similar.The results of the Spearman rank correlation analysis indicated that the average biomass of the macrobenthos and the biomass of the planktophagous group in the study area were negatively correlated with the water depth,sediment grain size and silt percentage.However,these variables were clearly not strong determinants of macrobenthos assemblage structure.Many factors not measured in the study,e.g.,sediment organic matter and iceberg interference,have probably influenced the spatial distribution of macrobenthic community structure in the Prydz Bay.  相似文献