Morphotaxonomy and seasonal distribution of planktonic and benthic Prorocentrales in Karachi waters, Pakistan Northern Arabian Sea     

Sonia MUNIR  Zaib-un-nisa BURHAN  Tahira NAZ  P.J.A.SIDDIQUI  Steve L.MORTON 《中国海洋湖沼学报》2013,31(2):267-281

Morphotaxonomy and seasonal abundance of dinoflagellates of the genera Prorocentrum and Mesoporos(Prorocentrales) were studied from nutrient-rich waters,Karachi Harbor and the mouth of the Manora Channel,Pakistan during May 2002-July 2003.Using both light and scanning electron microscopy,13 species of Prorocentrales were identified according to cell shape,size,ornamentation of thecal plates,and architecture of apical platelets,apical pore area,marginal pores,and intercalary bands.P.sigmoides,P.arcuatum,P.scutellum,P.donghaiense,P.balticum,P.minimum,P.emarginatum,P.lima,P.faustiae,and Mesoporos perforatus constitute new records for sindh coast of Pakistan.The most abundant species were P.minimum/P.balticum(4.5×103 cells/L),P.micans(1.1×103 cells/L),P.gracile/P.sigmoides(2.5×102 cells/L) and P.donghaiense(6.6×103 cells/L) at temperatures of 29-31℃ and salinities of 35-40.Maximum abundance was observed in winter and lower abundance in summer.There was no significant change in the distribution of species between stations except for the benthic species which occurred close to Karachi Harbor waters.Significant positive correlations were observed between Prorocentrum spp.and temperature(R 2 =0.27) and negative correlations with salinity(R 2 =-0.32) except for P.minimum and P.emarginatum which has negative correlation with temperature(R 2 =-0.24) and positive with salinity(R 2 =0.08,0.19).The finding of potential okadaic-acid producing species of benthic Prorocentrum call for monitoring for possible human health problems in this region.  相似文献   

Study on original ecological tridimensional slope vegetation     

Zhi-xin Yan  Zhi-hua Ren  Chang-ming Yan  Ping Jiang  Hou-yu Wang 《山地科学学报》2013,10(6):932-939

No matter from the perspective of slope protection, landscape effect and construction cost, or from the perspective of ecological benefit, the development of original ecological tridimensional vegetation has become the inevitable trend for slope vegetation in pursuit of protecting ecological condition, decreasing soil erosion, maintaining ecological balance and beautifying environment of slope. The concept of original ecological tridimensional slope vegetation is proposed in this paper, and the original ecological tridimensional slope vegetation is studied through theoretical analysis and experiments. Specifically, the mechanical effect of slope vegetation in reinforcing the cohesion and shear strength of soil mass is firstly discussed, and then experiments are performed to study the water interception and containing function of slope under various vegetation conditions. Moreover, the relation between soil moisture and cohesion, the relation between root distribution density and cohesion, and the relation between root distribution density and soil shear strength are also studied based on experiments. Finally, based on field observation, the soil erosion states of slope under various vegetation conditions are comparatively studied. It is found that the original ecological tridimensional slope, which combines grass,shrub and tree, can generate comprehensive slope protection effects, and hence strengthen the slope protection ability and bring multiple slope protection benefits. Thereby, the theoretical foundation for developing original ecological tridimensional slope vegetation is established.  相似文献   

中国西部社会、经济与生态的协调发展时空变化   总被引：4，自引：0，他引：4       下载免费PDF全文

张东海  任志远  冯雪铭  李双双 《干旱区地理》2013,36(3):545-552

采用层次分析法（AHP）建立中国西部社会、经济与生态评价指标体系,并计算社会、经济与生态指数,对西部各地区社会、经济与生态进行综合分析评价。通过构建耦合协调模型,定量分析了社会、经济与生态两两之间的发展模式。结果表明：（1）1990-2010年,西部各地区经济持续增长,其中甘肃以东地区经济发展显著,社会水平与经济发展保持平行提高,生态水平基本保持静止,而西南地区生态水平明显高于西北地区,西北地区生态水平波动大。（2）社会系统与经济系统的发展模式互动趋势明显,社会进步相对于经济发展具有短暂滞后性;而生态系统反映较迟钝,生态与社会、生态与经济模式的发展趋势不明显,但与环境库兹涅茨倒“U”型曲线发展模式一致。（3）中国西部各地区经济、社会和生态系统之间的协调度均呈增长趋势,说明随时间的推移,各个系统之间耦合协调度趋于协调发展。但2005年和2010年的协调度增长不明显,个别地区经济生态协调度出现下降趋势,生态水平的下降造成协调度增长停滞。  相似文献   

Retreating ice: research in pro‐glacial areas matters          下载免费PDF全文

Tobias Heckmann  Samuel McColl  David Morche 《地球表面变化过程与地形》2016,41(2):271-276

Glacier forefields are landscapes in transition from glacial to non‐glacial conditions; this implies intense geomorphic, hydrological and ecological dynamics with important on‐ and off‐site effects. This special issue collects 13 papers covering recent research in both (sub‐)polar and alpine pro‐glacial environments that focus on (i) pro‐glacial sediment sources, (ii) pro‐glacial rivers, (iii) pro‐glacial lakes, (iv) ground water and ice, and (v) the development of soil and vegetation in its interplay with morphodynamics. Advances in mapping, surveying and geophysical techniques form the basis for research perspectives related to the historical evolution of pro‐glacial areas, the understanding of complex interactions of multiple processes, and the effects of continued glacier recession. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

An interdisciplinary political ecology of drinking water quality. Exploring socio-ecological inequalities in Lilongwe’s water supply network     

《Geoforum》2017

Urban political ecology attempts to unravel and politicize the socio-ecological processes that produce uneven waterscapes. At the core of this analysis are the choreographies of power that influence how much water flows through urban infrastructure as well as where it flows, thereby shaping conditions and quality of access in cities. If these analyses have been prolific in demonstrating uneven distribution of infrastructures and water quantity, the political ecology of water quality remains largely overlooked. In this paper, we argue that there is a clear theoretical and practical need to address questions of quality in relation to water access in the South. We show that conceptual resources for considering differentiated drinking water quality are already present within urban political ecology. We then contend that an interdisciplinary approach, highlighting the interdependencies between politics, power, and physiochemical and microbiological contamination of drinking water, can further our understandings of both uneven distribution of water contamination and the conceptualisation of inequalities in the urban waterscape. We illustrate our argument through the case of water supply in Lilongwe, Malawi. Our political ecology analysis starts from an examination of the physicochemical and microbiological quality of water supplied by the formal water utility across urban spaces in Lilongwe. We then present the topography of water (quality) inequalities in Lilongwe and identify the political processes underlying the production of differentiated water quality within the centralised network. This paper thereby serves as a deepening of urban political ecology as well as a demonstration of how this approach might be taken forward in the analysis of urbanism and water supplies.  相似文献   

Racial coastal formation: The environmental injustice of colorblind adaptation planning for sea-level rise     

《Geoforum》2017

The United States’ deeply racialized history currently operates below the surface of contemporary apolitical narratives on vulnerability mitigation and adaptation to sea-level rise. As communities, regulatory agencies, and policy-makers plan for rising seas, it is important to recognize the landscapes of race and deep histories of racism that have shaped the socio-ecological formations of coastal regions. If this history goes unrecognized, what we label colorblind adaptation planning is likely to perpetuate what Rob Nixon calls the “slow violence” of environmental racism, characterized by policies that benefit some populations while abandoning others. By colorblind adaptation planning, we refer to vulnerability mitigation and adaptation planning projects that altogether overlook racial inequality—or worse dismiss its systemic causes and explain away racial inequality by attributing racial disparities to non-racial causes. We contend that responses to sea-level rise must be attuned to racial difference and structures of racial inequality. In this article, we combine the theory of racial formation with the geographical study of environmental justice and point to the ways racial formations are also environmental. We examine vulnerability to sea-level rise through the process of racial coastal formation on Sapelo Island, Georgia, specifically analyzing its deep history, the uneven racial development of land ownership and employment, and barriers to African American participation and inclusion in adaptation planning. Racial coastal formation’s potential makes way for radical transformation in climate change science not only in coastal areas, but other spaces as situated territorial racial formations.  相似文献   

Disputed water: Competing knowledge and power asymmetries in the Yali Alto basin,Chile     

《Geoforum》2017

Hydrological information – which plays a crucial role in resolving conflicts over water allocation and distribution – is commonly seen as apolitical. However, this type of information is seldom objective and free of biases. Instead, it is used to position arguments and interests in accordance with the prevailing political agendas. Information is structured by complex and conflicting networks of public and private stakeholder interests, further reconstituted in different periods of time and place. Based on a study of the upper Yali basin in the municipality of San Pedro de Melipilla, Chile, we show how knowledge about water is produced, circulated and applied in the context of water scarcity and emerging conflicts over access to groundwater. Building on the notion of the hydrosocial cycle, the qualitative study shows how the production of hydrological reports and its application in political decision-making have reinforced asymmetrical relationships between the stakeholders locked in water conflicts. The lack of capacity of local farmers and community organizations to translate experiences into codified hydrological knowledge further exacerbates these asymmetries. Agro-industrial companies operating in the basin use hydrological assessments to locate and shift the water scarcity problems to the users, whereas locals blame them for accumulating disproportionately large concentrations of water extraction rights. Results contribute to the existing literature on environmental knowledge, arguing that discourses on water scarcity are not objective but shaped by socio-political contingencies. Overemphasising on data and techno-science based information to support certain decisions may be misleading without first unveiling the knowledge production processes operating across power-laden landscapes.  相似文献   

Abundance and Ecology of Endemic Asterorotalia trispinosa from the Western Bay of Bengal: Implications for its Application as a Paleomonsoon Proxy     

Rajeev?SARASWAT  Manumalenki?MANASA  Thejasino?SUOKHRIE  Mohammad?Syed?SAALIM  Rajiv?NIGAM 《《地质学报》英文版》2017,91(6):2268-2282

A total of 97 surface sediment samples were collected from the continental shelf and slope of the western Bay of Bengal to assess the potential application of Asterorotalia trispinosa as a paleomonsoon proxy. The relative abundance of living as well as total (living and dead) A. trispinosa ranges from being absent to a maximum of ~31%. The highest abundance of A. trispinosa is close to the outfall region of the Ganga-Brahmaputra Rivers and decreases away from the river mouths. Contrary to that, A. trispinosa is rare in front of both the Cauvery and Pennar river outfall regions, in the central part of the western Bay of Bengal. The living A. trispinosa abundance is the lowest in between two major river systems, viz. Ganga-Brahmaputra-Mahanadi and Krishna-Godavari. The relative abundance of both the total and living A. trispinosa is strongly positively correlated with ambient seawater temperature, and negatively correlated with %Corg and salinity. Based on the spatial distribution, we conclude that A. trispinosa is stenohaline in nature, rather than euryhaline, and further that the increased relative abundance of A. trispinosa indicates warmer and only marginally hyposaline environment. Even though the ecological preference of A. trispinosa suggests it as a potential paleomonsoon proxy, the restricted distribution implies limited application.  相似文献   

Spatial and temporal variation of diverse inter‐tidal algal assemblages in Southwest O‘ahu          下载免费PDF全文

Traci Erin Cox  Heather L. Spalding  Michael S. Foster 《Marine Ecology》2017,38(3)

Spatial and temporal variation in tropical inter‐tidal communities is poorly known, making predictions about the effects of climate change and other anthropogenic disturbances difficult. Along Southwest O‘ahu, Hawai'i, local residents are concerned about the environmental effects of coastal development and the perceived loss of targeted algal species, which are collected for human consumption. To describe the coastal benthic community and better understand the processes that form and maintain it, the abundance and composition of macroalgae were sampled in the region's inter‐tidal zone from 2006 to 2015. Sixty‐six macroalgal species and two broad algal assemblages were identified that corresponded to substrate topography and sand influence at a similar tidal elevation. Along flat carbonate benches with a sand beach, Phaeophyceae and Rhodophytes occurred in almost equal proportions, while shores with slightly more topographic relief and angular substrate were dominated by Rhodophytes. Foliose or turf algal forms were most common. Surveys captured the local invasion of an alga, Avrainvillea sp. and significant declines in abundant macroalgae in 2015 after a period of unseasonably warm, calm water. Temporal changes in algal assemblages were related to maximum water temperature and wave height but not precipitation. Thus, algal assemblages appear to be structured by local beach morphology as they interact with sand and wave activity and episodically by unusual weather events. However, manipulation and continuous monitoring of the algal assemblages coupled to sensing of the localized environment is necessary to confirm factors related to assembly maintenance and recent species shifts.  相似文献   

Rapid invertebrate responses to macroalgal wrack: two novel field experiments on intertidal mudflats in Southern Australia          下载免费PDF全文

Allyson L. O'Brien  Liz Morris  Michael J. Keough 《Marine Ecology》2017,38(1)

Macroalgal wrack deposition along coasts is highly variable but it plays an important role in the structure and function of marine communities. To date, most research has focused on the effects of decomposing wrack as it assimilates into the system but little is known about the immediate effects of wrack when it is first deposited in the habitat. Freshly deposited wrack may either wash away after a short period (1–2 days) or remain in the habitat and decay depending on tide and weather conditions. To understand the effects of this dynamic resource we experimentally manipulated wrack deposits on intertidal mudflats in Port Phillip Bay, Victoria, Australia. We conducted two experiments using defaunated patches of wrack (300 g wet weight) that were a mixture of seagrass and macroalgae and measured community responses after 2 days. The first experiment included real and artificial wrack patches to differentiate between taxa that responded to the biological and physical structure of the wrack. The second experiment used multiple wrack patches to investigate responses to a focal wrack patch that was surrounded by varying numbers of wrack additional patches (0, 2 or 4 × 300 g wet weight of wrack). Overall, wrack increased abundances of invertebrates and changed their distributions throughout the wrack and underlying sediment habitat. Mechanisms responsible for immediate taxa responses to the wrack related to the physical structure in the habitat and not biological attributes associated with the real patches. Ostracods and leptostracans were the exception to these patterns with colonization only occurring in real wrack and not the artificial wrack. In the multiple patch experiment the majority of the fauna moved vertically into the wrack from the bare sediment and not between surrounding patches of wrack. We suggest that specific characteristics, such as invertebrate mobility, feeding mode and sensitivity to changes in sediment condition, are important factors that influence individual taxa and overall community responses. Understanding the interactive effects of these characteristics with the characteristics of the wrack (magnitude, frequency, spatial arrangement and composition) is the key to developing predictive models that will inform the management of wrack in marine coastal habitats.  相似文献