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The occurrence of Tubiluchus corallicola (van der Land) in a lagoon on the East coast of Barbados, West Indies, is reported. 23 adult and 2 larval specimens were found in a sample taken from a subtidal stromatolite on which the animals presumably inhabited the algal surface layer. A comparison with data from earlier findings shows that the species is not confined to a particular type of substratum, yet morphologically it seems to be well adapted for a life in the interstitial sand habita. For the first time, living animals were observed and photographed. Their behavior and movements are briefly described and an account of morphological and histological details, as seen in squeezing preparations and photomicrographs, is presented.Supported in part by NSF Grant GB-7952 相似文献
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From spatial models to spatial evaluation in the analysis of wetland restoration in the Vecht river basin 总被引:1,自引:0,他引:1
Alison J. Gilbert Marjan van Herwijnen Carolin M. Lorenz 《Regional Environmental Change》2004,4(2-3):118-131
Water tables are strictly controlled throughout much of the Netherlands. Higher water tables could permit the restoration of wetland ecosystems. Deriving benefits from this requires the spatial matching of physical planning, eco-hydrological processes, and economic activities. This paper reports on a study combining spatial analysis and disciplinary integration to assess management strategies for the Vecht river basin in the Netherlands. The paper addresses two research questions. How can the information generated by spatial models be condensed into performance indicators for the evaluation of strategies? How can spatial information be retained in the evaluation, and does this lead to different rankings and/or insights? Procedures for the construction of performance indicators for three criteria – net present value, environmental quality and spatial equity – are presented. The evaluation concludes that recreation and higher water tables provide a means for restoration, recouping of costs, and stimulating regional incomes. Maintenance of spatial detail led to different insights, and in particular indicated uncertainty about this conclusion. 相似文献
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Integrated Coastal Zone Management as a strategy for achieving conservation and sustainable multiple use of the coastal zone
includes various types of management initiatives. Due to natural phenomena such as tides and winds and to social and economic
activities, coastal areas undergo transformation. Coastal erosion and the disappearance of beaches as a result of wrong planning
decisions and lack of effective legislation are among the most damaging effects and to reverse them requires application of
a series of engineering techniques. Beach nourishment projects as a way towards shore protection and utilization through recreational
purposes in the Spanish and Italian coasts are noteworthy in this respect.
In beach nourishment projects, the roles of various entities, both public and private, should be clearly indicated and in
the evaluation and execution stage a series of questions should be answered for the successful completion of any nourishment
project. Past projects in the Mediterranean and experiences from recent Italian projects in Anzio and Nettuno confirm this.
For example, dredging of the entrance channel of the port of Anzio enabled middle-sized ferryboats once again to enter the
port (which had not been possible before). This will in turn increase the tourism potential of the town. Nourishment of two
beaches at these sites prevented further erosion and provided more area for recreational purposes. Expected economic contribution
of beach nourishments to the regional authority was estimated for Nettuno and Anzio; the resulting theoretical payback period
was found to be 3 yr for the former and 15 yr for the latter. 相似文献
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