Benthic macroinvertebrates as indicators of environmental deterioration in a large microtidal estuary   总被引：1，自引：0，他引：1  

Wildsmith MD  Rose TH  Potter IC  Warwick RM  Clarke KR 《Marine pollution bulletin》2011,62(3):525-538

This study tested the hypothesis that, during recent years, the benthic macroinvertebrate fauna of the large basin of the Swan-Canning Estuary has changed in ways consistent with deteriorating environmental conditions in that estuary. Between 1986/7 and 2003/4, the compositions of that fauna altered markedly at the species and even family levels. Thus, the densities and number of species of molluscs, and especially of crustaceans, which are particularly susceptible to environmental stress, declined, while those of the more tolerant polychaetes increased. However, taxonomic distinctness declined consistently only at one of the four widely-spaced sampling sites and the dispersion of samples did not differ markedly between periods, indicating that the benthic fauna has not undergone such extreme changes as in the nearby Peel-Harvey Estuary. It is thus proposed that benthic macroinvertebrates can act as important indicators of the severity of environmental degradation in microtidal estuaries in regions where such perturbations are increasing.  相似文献   

Zooplankton succession during extraordinary drought–flood cycles: A case study in a South American floodplain lake     

Griselda Chaparro  María Cristina Marinone  Ruben J. Lombardo  María Romina Schiaffino  Alice de Souza Guimarães  Inés O’Farrell 《Limnologica》2011,41(4):371-381

We examined the zooplankton abundance and composition of Laguna Grande, a floodplain wetland of the Lower Paraná Basin (Argentina), during an extraordinary drought–flood cycle that affected both the environment and the biological conditions of the lake. Low waters were characterised by remarkably high conductivities and pH values, and high phytoplankton and bacterioplankton abundances with cyanobacterial blooms, while high waters showed opposite features. In relation to zooplankton, the mean abundances of all the taxonomic groups (rotifers, cladocerans, copepods, ciliates, and heterotrophic nanoflagellates) were slightly higher at low waters. Major changes were observed in the specific composition of metazooplankton: the euryhaline species assemblage that dominated in the dry warm period was replaced by several oligohaline littoral and planktonic species characteristic of the Paraná River Basin, when the water level rose. Mean species richness values at high waters doubled those of low waters and were directly correlated to water depth. Most of the rotifers of the genus Brachionus and the cladoceran Moina micrura switched from parthenogenetic to sexual reproduction during low waters, as a response to a harsh environment and crowding. We suggest that the main changes in the environmental conditions in this eutrophic floodplain lake are driven by the hydrology, which regulates the zooplankton succession. The herein described shifts in the zooplankton structure and dynamics of Laguna Grande over an extraordinary drought–flood cycle contribute to the understanding of the processes that might occur under the scenarios predicted by climate change models.  相似文献   

Community Development Finance Institutions (CDFIs): Geographies of financial inclusion in the US and UK     

Lindsey Appleyard 《Geoforum》2011,42(2):250-258

The financial exclusion of enterprise is a concept that has been largely neglected by economic geographers. This is surprising given the attention dedicated to personal financial exclusion and alternative sources of finance. This paper compares financial inclusion policies in deprived areas of the United States (US) and United Kingdom (UK) through the example of Community Development Finance Institutions (CDFIs). CDFIs help overcome financial exclusion by providing local sources of loan finance to micro, small-and-medium-sized enterprises and social enterprises. Drawing upon interviews with key actors within the CDFI sector in the US and UK respectively, the paper aims to compare the CDFI landscape across the US and UK through the provision of finance for enterprise. This is in order to understand the geographies of finance that are being created by such alternative financial institutions thereby contributing to financial inclusion debates. The research concludes that although CDFIs do provide an important source of finance to excluded enterprises, policy initiatives have created uneven geographical coverage and market gaps leaving marked spaces of financial exclusion.  相似文献   

山东乳山近海海洋卡盾藻(Chattonella marina)赤潮发展过程及其成因研究          下载免费PDF全文

宋秀凯  袁廷柱  孙玉增  石雅君  靳洋  白艳艳  张利民 《海洋与湖沼》2011,42(3):425-430

于 2008 年 8 月 10—28 日, 在山东乳山近海赤潮发生海域采用直接采水计数法对浮游植物种类组成进行了 4 次跟踪监测。结果表明, 此次赤潮主要由海洋卡盾藻引起, 面积约 100km², 平均密度 1.46×10⁶ cells/L, 占浮游植物总数的 91.32%。 从 8 月 19 日开始, 海洋卡盾藻赤潮开始消退, 同时中肋骨条藻和尖刺拟菱形藻密度增高, 到 8 月 28 日本次赤潮完全消失。研究发现, 该海域富营养化、低盐度的理  相似文献   

Fishing dynamics associated with periodically harvested marine closures     

Philippa J. Cohen  Joshua E. Cinner  Simon Foale 《Global Environmental Change》2013,23(6):1702-1713

Periodically-harvested fisheries closures are emerging as a socially acceptable and locally implementable way to balance concerns about conserving ecosystem function and sustaining livelihoods. Across the Indo-Pacific periodically-harvested closures are commonly employed, yet their contribution towards more sustainable fisheries remains largely untested in the social and ecological context of tropical small-scale fisheries. To address this, we use an interdisciplinary approach to examine harvesting dynamics that would affect sustainability, namely, fishing effort, yield, gear and method use, periodicity of harvesting, controls placed on harvesting and resource owners’ decisions to open and close four fishing grounds in Solomon Islands. We compare these fishing patterns with those on surrounding, continuously open fishing grounds. Our study shows that total effort and total catch from periodically-harvested reef closures are low to moderate compared to reefs open to continuous fishing. When periodically-harvested closures were opened, effort in the closures was relatively intense, however, in most cases yield did not exceed annual benchmarks of sustainability described by previous studies. In some cases, harvesting during openings was restricted to a single taxon and single fishing gear and method, while in others there was unrestricted multi-species and multi-method harvesting. The duration and frequency of openings were highly variable, with open periods ranging from a single night to one month in duration, and occurring between one and 15 times per year. Fishing during openings was permitted for entire fishing communities in some cases, and only for specific rights-holding families in others. Decisions to open periodically-harvested closures tended to be based on immediate social or economic needs, and the openings provided a small boost to fish catch landed in communities. While periodically-harvested closures may alleviate fishing pressure in a small area of fishing grounds by reducing the opportunity to fish, openings of long duration or high frequency, combined with heavy or destructive exploitation, may lead to unsustainable harvesting within the area.  相似文献   

湿性常绿阔叶林区次生环境鸟类群落动态研究     

王直军 《云南地理环境研究》1990,2(1):46-52

本文分析了云南哀牢山中山湿性常绿阔叶林区次生环境中鸟类群落的年动态。各类次生环境中,鸟类群落多样性和稳定性之间并非成简单的正相关。比气候顶极群落结构简单的林缘、林窗次生植被中的鸟类群落具有较高的物种多样性,但其群落稳定性较差;在植被简单的沼泽化草甸环境鸟类群落物种的多样性低,却表现其群落结构的稳定性。鸟类群落的稳定性与其生境的稳定性相关。在林缘、林窗鸟种类和密度变化显著,鸟类传播植物种子促进林缘、林窗地带自然更新和植被复化,能加速次生植被恢复到顶极群落的进程。  相似文献   

Vicarious scale and instrumental imaginaries in community sustainable transitions     

《Global Environmental Change》2022

Community initiatives are often charged with scaling-up: growing, deepening their impacts, and seeding off new projects. The desire to scale-up comes from both within the community initiatives themselves, and is also encouraged by all levels of policy, from local government, to national and international frameworks such as the IPCC. This paper adds to critiques of this agenda, by leaning on human geography writings on scale, and introducing the concept of ‘vicarious scale’. This concept is drawn from empirical work which highlights the double move of scaling-up. This double move, first, restricts and contains community within a local, small, or narrow limit. Then, concurrently, expects this restricted community to have displaced effects: at a higher scale, or a distant point in time. It argues that the scaling-up expectations are both placed onto community initiatives and emerge from within them, and that these expectations are both counterproductive to realizing the full potential of community, and accompany an insertion of instrumental logic onto and into these community initiatives. Appreciating vicarious scale also has important practical implications for communities—not least being wary of the counterproductive and corrosive effects a will-to-grow can have.  相似文献   

Conflicted transitions: Exploring the actors,tactics, and outcomes of social opposition against energy infrastructure     

《Global Environmental Change》2022

Given the growing frequency, severity, and salience of social mobilization and community action on energy and climate issues, in this study we systematically explore the configurations of types of infrastructure, actors, tactics, and outcomes of recent opposition to energy transitions across seven carbon-intensive regions in Asia, Europe, and North America. Based on both a literature review and an original dataset of 130 case studies spanning the past decade, we track opposition to a wide range of energy infrastructure in these regions, including low-carbon options such as renewable energy and nuclear power; provide network analyses of the actors and coalitions involved in such events; and develop a typology and frequency analysis of tactics (such as litigation or protest), and outcomes (such as remuneration, policy change, concessions, or labor protections). We show that the politics of energy transitions in carbon-intensive regions varies significantly from country to country and across types of energy, and we discuss how the configurations of infrastructure, actors, tactics, and outcomes can be explained by differences in national institutions and their responses to global or supranational pressures. By bringing both a sociotechnical and comparative perspective to the global analysis of social movements and energy transitions, we suggest how goals of energy transition are refracted through national and subnational institutions and through local mobilizations both in support of and opposed to those transitions.  相似文献   

Autonomy in a post-neoliberal era: Community water governance in Cochabamba,Bolivia     

《Geoforum》2015

Bolivia’s leftward political shift, which is frequently described as “post-neoliberal,” is crucially linked to the ideal of autonomy. While autonomy has a long history among leftist theorists and social movements in Latin America, its contemporary importance is related to an ongoing effort on the part of scholars and activists to identify an alternative organizational form that eschews both state actors and private entities. Drawing on fieldwork conducted with a group of community-run water systems in peri-urban Cochabamba, this paper asks what autonomous water governance looks like in practice. By presenting a case in which the community water systems made a series of structurally limited “autonomous” decisions that ultimately bound them more closely to the local state and private sector, the paper argues that autonomy faces socio-ecological limitations when conceptualized as a project of internal self-governance. Socio-ecological processes take place at multiple scales and over long time spans; a radical politics of autonomy therefore necessitates a spatially extroverted project that focuses on building strategic alliances that strengthen community autonomy in the long-term.  相似文献   

The evolving role of finance in South Africa’s renewable energy sector     

《Geoforum》2015

In the last four years, carbon-intensive, coal-dependent South Africa has become one of the leading global destinations for renewable energy investment. This investment can be attributed to the unprecedented take off of the country’s Renewable Energy Independent Power Producers’ Programme (RE IPPPP), a bidding process for the procurement of privately generated, utility scale renewable energy, launched in August 2011. Asserting that energy must be studied within the broader economic, political and social forces in which it is embedded, I explore the fundamental role that different modes of finance have played in shaping South Africa’s emerging renewable energy sector within the context of the country’s unique system of accumulation characterised by its minerals-energy complex (MEC) (Fine and Rustomjee, 1996). I focus on finance and financialisation as growing features within the MEC. I further examine the tension or incompatibility between commercial demands for ‘bankability’, short-term shareholder value and impatient finance and RE IPPPP’s unique requirements for community ownership of projects and the realisation of economic development criteria. I find that a reconfiguration of long-standing MEC actors, particularly in the realms of finance is taking place as they merge with new sources of foreign capital.  相似文献