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Stig Skreslet Terje Doksr⊘d Morten Frogh Morten Krogstad Ketil Olsen 《Coastal management》2013,41(2):141-152
A simple numerical model was applied to distinguish permanently oxygenated marine sill basins from periodically anoxic basins in Nordland County, northern Norway. Input data are sill depth, width of the tidal channel, sea surface area, and tidal range. The model produces a Topography Tidal Factor (TTF) that seems to be an adequate index correlating with empirical field data when sills have saddle depths <30 m. The depth of the pycnocline, and the oxygen concentration of the basin water increases logarithmically with the calculated TTF value toward an asymptotic level. At TTF ≥0.02 basins are mostly well-oxygenated and have a permanent fauna of epibenthic and hyperbenthic animals. Basins with TTF <0.02 may become anoxic each autumn, which permanently prevents establishment of communities with multi-annual sessile benthos. Low oxygen concentration may also cause seasonal variation in the occurrence of motile species. In tidal channels, the abundance of bivalves and fish, as well as the biodiversity in general, probably increases with TTF. The applied method may be universally valid in regions shaped by glacial erosion but needs to be further developed by more detailed studies. 相似文献
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The experience in coastal management in the tropics that is presented in this special issue is considered in light of other coastal management initiatives worldwide. The major challenges confronting those working to promote cross-sectoral, participatory approaches to the management of coastal areas are discussed. Emerging conceptual frameworks are considered. Several factors critical to the design of coastal management projects and programs are identified. The article concludes with a reflection on priorities for furthering the practice of coastal management in the next decade. 相似文献
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Air–sea fluxes in the Caribbean Sea are presented based on measurements of partial pressure of CO2 in surface seawater, pCO2sw, from an automated system onboard the cruise ship Explorer of the Seas for 2002 through 2004. The pCO2sw values are used to develop algorithms of pCO2sw based on sea surface temperature (SST) and position. The algorithms are applied to assimilated SST data and remotely sensed winds on a 1° by 1° grid to estimate the fluxes on weekly timescales in the region. The positive relationship between pCO2sw and SST is lower than the isochemical trend suggesting counteracting effects from biological processes. The relationship varies systematically with location with a stronger dependence further south. Furthermore, the southern area shows significantly lower pCO2sw in the fall compared to the spring at the same SST, which is attributed to differences in salinity. The annual algorithms for the entire region show a slight trend between 2002 and 2004 suggesting an increase of pCO2sw over time. This is in accord with the increasing pCO2sw due the invasion of anthropogenic CO2. The annual fluxes of CO2 yield a net invasion of CO2 to the ocean that ranges from − 0.04 to − 1.2 mol m− 2 year− 1 over the 3 years. There is a seasonal reversal in the direction of the flux with CO2 entering into the ocean during the winter and an evasion during the summer. Year-to-year differences in flux are primarily caused by temperature anomalies in the late winter and spring period resulting in changes in invasion during these seasons. An analysis of pCO2sw before and after hurricane Frances (September 4–6, 2004), and wind records during the storm suggest a large local enhancement of the flux but minimal influence on annual fluxes in the region. 相似文献
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Morphology is the subject matter of study in physical and biological sciences. A few attempts have been made to apply the biologists’ and paleontologists’ morphological study model known as allometry to social sciences fields and urbanization dynamics. However in social and sociocultural situations all forms are changeable by volition and policy, as opposed to being the result of fixed information which is stored in the genes. In studying metropolitan areas it is advantageous to regard the allometric relations as merely morphological relations indicating norms by which the components of the system change in relation to the change of the whole system. The morphological analysis approach for a metropolitan highway system has been formulated by utilizing relations defined in the Tri‐State metropolitan area (Connecticut, New Jersey, and New York). The study demonstrates that this approach is suitable for highway network planning and comprehensive policy design. 相似文献
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Comment by John R. Clark Comment by Kem Lowry Comment by Stephen B. Olsen Response by Jens Sorensen 相似文献
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