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51.
Since the 1980s, there have been continuous increases in the coverage of marine protected areas (MPAs) in China, and a total of 158 MPAs have been declared. The MPA system in China is characterized by (1) decentralised designation and management with reduced control from the central government; (2) a dominance of de jure fully protected MPAs that are often implemented as de facto multiple-use areas; and (3) a lack of objective evaluation processes. To improve China's MPA system requires an appropriate integration of fully protected and multiple-use MPAs, and an approach that balances the advantages of top-down and bottom-up approaches.  相似文献   
52.
This paper analyses effects of a shift from input to output controls in Australia's Southern Shark Fishery. We show that the use of two management tools—individual transferable quotas and a “partnership approach”—was flawed and argue that primary contributing causes were the unjustified expectation that quota management would serve as a ‘technical fix’ to a variety of presumed problems, the discounting of social effects and the extreme lack of stability in the organizational structure within which this fishery was situated.  相似文献   
53.
Tectonic evolution of the Cape and Karoo basins of South Africa   总被引:1,自引:0,他引:1  
The Cape and Karoo basins formed within the continental interior of Gondwana. Subsidence resulted from the vertical motion of rigid basement blocks and intervening crustal faults. Each basin episode records a three-stage evolution consisting of crustal uplift, fault-controlled subsidence, and long periods of regional subsidence largely unaccompanied by faulting or erosional truncation. The large-scale episodes of subsidence were probably the result of lithospheric deflection due to subduction-driven mantle flow. The early Paleozoic Cape basin records the combined effects of a north-dipping intra-crustal décollement (a late Neoproterozoic suture) and a right-stepping offset between thick Rio de la Plata craton and Namaqua basement. Following the Saldanian orogeny, a suite of small rift basins and their post-rift drape formed at this releasing stepover. Great thicknesses of quartz sandstone (Ordovician–Silurian) and mudstone (Devonian) accumulation are attributed to subsidence by rheological weakening and mantle flow. In contrast, the Karoo basin is a cratonic cover that mimics the underlying basement blocks. The Permian Ecca and lower Beaufort groups were deposited in a southward-deepening ramp syncline by extensional decoupling on the intra-crustal décollement. Reflection seismic and deep-burial diagenetic studies indicate that the Cape orogeny started in the Early Triassic. Deformation was partitioned into basement-involved strike-slip faults and thin-skinned thrusting. Uplift of the Namaqua basement resulted in erosion of the Beaufort cover. East of the Cape fold belt, contemporaneous subsidence and tilting of the Natal basement created a late Karoo transtensional foreland basin, the Stormberg depocentre. Early Jurassic tectonic resetting and continental flood basalts terminated the Karoo basin.  相似文献   
54.
Internal solitary wave propagation over a submarine ridge results in energy dissipation, in which the hydrodynamic interaction between a wave and ridge affects marine environment. This study analyzes the effects of ridge height and potential energy during wave-ridge interaction with a binary and cumulative logistic regression model. In testing the Global Null Hypothesis, all values are p 〈0.001, with three statistical methods, such as Likelihood Ratio, Score, and Wald. While comparing with two kinds of models, tests values obtained by cumulative logistic regression models are better than those by binary logistic regression models. Although this study employed cumulative logistic regression model, three probability functions p^1, p^2 and p^3, are utilized for investigating the weighted influence of factors on wave reflection. Deviance and Pearson tests are applied to cheek the goodness-of-fit of the proposed model. The analytical results demonstrated that both ridge height (X1 ) and potential energy (X2 ) significantly impact (p 〈 0. 0001 ) the amplitude-based refleeted rate; the P-values for the deviance and Pearson are all 〉 0.05 (0.2839, 0.3438, respectively). That is, the goodness-of-fit between ridge height ( X1 ) and potential energy (X2) can further predict parameters under the scenario of the best parsimonious model. Investigation of 6 predictive powers ( R2, Max-rescaled R^2, Sorners' D, Gamma, Tau-a, and c, respectively) indicate that these predictive estimates of the proposed model have better predictive ability than ridge height alone, and are very similar to the interaction of ridge height and potential energy. It can be concluded that the goodness-of-fit and prediction ability of the cumulative logistic regression model are better than that of the binary logistic regression model.  相似文献   
55.
Internal solitary wave propagation over a submarine ridge results in energy dissipation, in which the hydrodynamic interaction between a wave and ridge affects marine environment. This study analyzes the effects of ridge height and potential energy during wave-ridge interaction with a binary and cumulative logistic regression model. In testing the Global Null Hypothesis, all values are p<0.001, with three statistical methods, such as Likelihood Ratio, Score, and Wald. While comparing with two kinds of models, tests values obtained by cumulative logistic regression models are better than those by binary logistic regression models. Although this study employed cumulative logistic regression model, three probability functions p^1, p^2 and p^3, are utilized for investigating the weighted influence of factors on wave reflection. Deviance and Pearson tests are applied to check the goodness-of-fit of the proposed model. The analytical results demonstrated that both ridge height (X1) and potential energy (X2) significantly impact (p<0.0001) the amplitude-based reflected rate; the P-values for the deviance and Pearson are all >0.05 (0.2839, 0.3438, respectively). That is, the goodness-of-fit between ridge height (X1) and potential energy (X2) can further predict parameters under the scenario of the best parsimonious model.Investigation of 6 predictive powers (R2, Max-rescaled R2, Somers'D, Gamma, Tau-a, and c, respectively) indicate that these predictive estimates of the proposed model have better predictive ability than ridge height alone, and are very similar to the interaction of ridge height and potential energy. It can be concluded that the goodness-of-fit and prediction ability of the cumulative logistic regression model are better than that of the binary logistic regression model.  相似文献   
56.
Sponges provide the largest number of biologically active natural products known from the marine environment and continue to be a very well studied phylum of marine fauna. The Mediterranean sponge Aplysina aerophoba accumulates brominated isoxazoline alkaloids such as Aplysinamisin-1, Aerophobin-2, Isofistularin-3 and the biotransformation product Aeroplysinin-1, which possesses, for example, antibiotic and cytotoxic properties. Until now, it is still being discussed which organisms – the sponge itself or associated microorganisms – are responsible for metabolite production. For cultivating Aplysina individuals under ex situ conditions, we surveyed relevant ecological factors in situ and controlled them in our aquarium system. We maintained A. aerophoba for more than 9 months and analysed changes of metabolite content and composition, microbial association as well as morphology in situ and ex situ under different light exposure. Although sponges showed slight reduction during maintenance, ex situ cultivation similar to in situ conditions provides a promising method to keep sponges and obtain their bioactive metabolites.  相似文献   
57.
58.
Weather in the North Gulf of Alaska is characterized by a high frequency of deep synoptic-scale low-pressure systems, especially during the cold season. The strong pressure gradients of these storms interact with the extremely rugged terrain of the coastal mountains to produce a variety of channeled flows. These surface wind regimes are not well documented in the scientific community, due to the paucity of observations. Modeling of these phenomena in regions of complex terrain is of great interest to those working with hydrodynamic, wave, and pollutant transport models in coastal and shelf areas. Such models, when coupled with ocean and coastal-ecology counterparts, give a broad view of the role surface winds play in shaping local coastal marine ecosystem in this region. This paper presents a climatology of simulated low-level wind jets over the domain of Cook Inlet and Shelikof Strait along Alaska's south-central coast. Daily simulations using the RAMS model were conducted in a 36-h forecast mode for the cold-season period 10/1/03 to 3/31/04. Systematic analysis of the resulting simulated low-level wind field makes it possible to characterize these jets and gap flows in spatial and temporal detail. The comparison between the RAMS winds and the Synthetic Aperture Radar (SAR)-derived winds when available verifies the existence of these wind jets and the capability of the model to simulate these cases. Clearly, the results of a study in this region depend on the fidelity of the model at these scales (O[5 km]). The SAR comparisons attempt to help establish this. From the 6 months of simulations over Cook Inlet and Shelikof Strait, the low-level wind jets are classified into 10 different regimes by location and orientation. These regimes are categorized into four more general groups: cross-channel westerly, easterly, and up and down Inlet flows. The nature of a particular regime is largely a function of pressure gradient orientation and local topography. Jets in the same group have a similar occurrence distribution with time. Some form of jet occurred in the study region almost daily each month of the period, with December 2003 having the highest frequency of wind jets.  相似文献   
59.
Prediction of coastal hazards due to climate change is fraught with uncertainty that stems from complexity of coastal systems, estimation of sea level rise, and limitation of available data. In-depth research on coastal modeling is hampered by lack of techniques for handling uncertainty, and the available commercial geographical information systems (GIS) packages have only limited capability of handling uncertain information. Therefore, integrating uncertainty theory with GIS is of practical and theoretical significance. This article presents a GIS-based model that integrates an existing predictive model using a differential approach, random simulation, and fuzzy set theory for predicting geomorphic hazards subject to uncertainty. Coastal hazard is modeled as the combined effects of sea-level induced recession and storm erosion, using grid modeling techniques. The method is described with a case study of Fingal Bay Beach, SE Australia, for which predicted responses to an IPCC standard sea-level rise of 0.86 m and superimposed storm erosion averaged 12 m and 90 m, respectively, with analysis of uncertainty yielding maximum of 52 m and 120 m, respectively. Paradoxically, output uncertainty reduces slightly with simulated increase in random error in the digital elevation model (DEM). This trend implies that the magnitude of modeled uncertainty is not necessarily increased with the uncertainties in the input parameters. Built as a generic tool, the model can be used not only to predict different scenarios of coastal hazard under uncertainties for coastal management, but is also applicable to other fields that involve predictive modeling under uncertainty.  相似文献   
60.
ABSTRACT

From September to October 2002, shallow drilling, using the submersible (5 m) Rockdrill of the British Geological Survey and the German R/V Sonne revealed critical information on the subsurface nature of two distinct hydrothermal systems in the New Ireland fore-arc and the Manus Basin of Papua New Guinea. Drilling at Conical Seamount significantly extends the known surface extent of the previously discovered vein-style gold mineralization (up to 230 g/t Au) at this site. Drilling the conventional PACMANUS volcanic-hosted massive sulfide deposit recovered complexly textured massive sulfide with spectacular concentrations of gold in several core sections including 0.5 m @ 28 g/t Au, 0.35 m @ 30 g/t Au, and 0.20 m @ 57 g/t Au. Shallow drilling is a fast and cost efficient method that bridges the gap between surface sampling and deep (ODP) drilling and will become a standard practice in the future study of seafloor hydrothermal systems and massive sulfide deposits.  相似文献   
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