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21.
Chad L. Hewitt Marnie L. Campbell Ronald E. Thresher Richard B. Martin Sue Boyd Brian F. Cohen David R. Currie Martin F. Gomon Michael J. Keough John A. Lewis Matthew M. Lockett Nicole Mays Matthew A. McArthur Tim D. O'Hara Gary C. B. Poore D. Jeff Ross Melissa J. Storey Jeanette E. Watson Robin S. Wilson 《Marine Biology》2004,144(1):183-202
Port Phillip Bay (PPB) is a large (1,930 km2), temperate embayment in southern Victoria, Australia. Extensive bay-wide surveys of PPB have occurred since 1840. In 1995/1996 the Commonwealth Scientific and Industrial Research Organization (CSIRO) Centre for Research on Introduced Marine Pests (CRIMP) undertook an intensive evaluation of the region with the aims of developing a comprehensive species list of native and introduced biota and contrasting previous bay-wide assessments with a current field survey in order to detect new incursions and discern alterations to native communities. Two methods were used to meet these aims: a re-evaluation of regional museum collections and published research in PPB to identify and determine the timing of introductions; and field surveys for benthic (infauna, epifauna and encrusting) organisms between September 1995 to March 1996. One hundred and sixty introduced (99) and cryptogenic (61) species were identified representing over 13% of the recorded species of PPB. As expected, the majority of these are concentrated around the shipping ports of Geelong and Melbourne. Invasions within PPB appear to be increasing, possibly due to an increase in modern shipping traffic and an increase in aquaculture (historically associated with incidental introductions); however the records of extensive biological surveys suggest that this may, in part, be an artefact of sampling effort. In contrast to Northern Hemisphere studies, PPB (and Southern Hemisphere introductions in general) have significantly different suites of successfully invading taxa. PPB is presented as one of the most invaded marine ecosystems in the Southern Hemisphere.Communicated by M.S. Johnson, Crawley 相似文献
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Kennedy N. Igbokwe 《中国人口.资源与环境(英文版)》2005,(1)
1 INTRODUCTIONIn the past, natural resources management initiatives havefocused on large but specific sector projects such as dams,reservoirs for water supply schemes, irrigation systems,crop production, at forestation, etc. Often these projectswere treated as technical and administrative issues ratherthan as a socio-economic and political one. However, thehigh social and environmental cost of such schemes haveled to a change of paradigm since the 1980s towards small-scale community projec… 相似文献
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Frank Eierdanz Joseph Alcamo Lilibeth Acosta-Michlik Dörthe Krömker Dennis Tänzler 《Regional Environmental Change》2008,8(4):197-205
This paper presents the technical aspects of a new methodology for assessing the susceptibility of society to drought. The
methodology consists of a combination of inference modelling and fuzzy logic applications. Four steps are followed: (1) model
input variables are selected—these variables reflect the main factors influencing susceptibility in a social group, population
or region, (2) fuzzification—the uncertainties of the input variables are made explicit by representing them as ‘fuzzy membership
functions’, (3) inference modelling—the input variables are used to construct a model made up of linguistic rules, and (4)
defuzzification—results from the model in linguistic form are translated into numerical form, also through the use of fuzzy
membership functions. The disadvantages and advantages of this methodology became apparent when it was applied to the assessment
of susceptibility from three disciplinary perspectives: Disadvantages include the difficulty in validating results and the
subjectivity involved with specifying fuzzy membership functions and the rules of the inference model. Advantages of the methodology
are its transparency, because all model assumptions have to be made explicit in the form of inference rules; its flexibility,
in that informal and expert knowledge can be incorporated through ‘fuzzy membership functions’ and through the rules in the
inference model; and its versatility, since numerical data can be converted to linguistic statements and vice versa through
the procedures of ‘fuzzification’ and ‘defuzzification’. 相似文献