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1.
ABSTRACT. The excessive and unsustainable exploitation of our marine resources has led to the promotion of marine reserves as a fisheries management tool. Marine reserves, areas in which fishing is restricted or prohibited, can offer opportunities for the recovery of exploited stock and fishery enhancement. In this paper we examine the contribution of fully protected tropical marine reserves to fishery enhancement by modeling marine reserve‐fishery linkages. The consequences of reserve establishment on the long‐run equilibrium fish biomass and fishery catch levels are evaluated. In contrast to earlier models this study highlights the roles of both adult (and juvenile) fish migration and larval dispersal between the reserve and fishing grounds by employing a spawner‐recruit model. Uniform larval dispersal, uniform larval retention and complete larval retention combined with zero, moderate and high fish migration scenarios are analyzed in turn. The numerical simulations are based on Mombasa Marine National Park, Kenya, a fully protected coral reef marine reserve comprising approximately 30% of former fishing grounds. Simulation results suggest that the establishment of a fully protected marine reserve will always lead to an increase in total fish biomass. If the fishery is moderately to heavily exploited, total fishery catch will be greater with the reserve in all scenarios of fish and larval movement. If the fishery faces low levels of exploitation, catches can be optimized without a reserve but with controlled fishing effort. With high fish migration from the reserve, catches are optimized with the reserve. The optimal area of the marine reserve depends on the exploitation rate in the neighboring fishing grounds. For example, if exploitation is maintained at 40%, the ‘optimal’ reserve size would be 10%. If the rate increases to 50%, then the reserve needs to be 30% of the management area in order to maximize catches. However, even in lower exploitation fisheries (below 40%), a small reserve (up to 20%) provides significantly higher gains in fish biomass than losses in catch. Marine reserves are a valuable fisheries management tool. To achieve maximum fishery benefits they should be complemented by fishing effort controls.  相似文献   
2.
兴宁市儿童及成人微量元素水平调查分析   总被引:3,自引:0,他引:3  
为提高人口素质,促进儿童身体健康,对广东省兴宁市儿童及成人的微量元素水平进行了调查。结果表明,本地区微量元素异常率达85.16%。提示必须防止铅污染,排铅补锌。  相似文献   
3.
开展正常人体内元素含量的检测研究具有重要生物学意义,不仅可充实我国正常成年人脏器组织元素含量值的基础医学数据,为研究人体内微量元素与健康的关系提供科学依据、也为辐射防护领域内放射性核素的剂量估算提供重要参数。本文从以下五个方面进行了论述:()体内元素含量检测研究的目的、意义及其概况;(2)元素含量检测的重要性及其历史沿革;(3)元素的检测方法及质量控制;(4)人体内脏器组织元素含量的数值;(5)与国外资料相比较。本文着重介绍了我国100例正常成年人20个脏器组织(包括胃、小肠、大肠、心、肝、脾、肺、肾、…  相似文献   
4.
A new xenicane diterpenoid, 15-deoxy-isoxeniolide-A (1) along with four known compounds 9-deoxy-isoxeniolide-A (2), isoxeniolide-A (3), xeniolide-A (4) and coraxeniolide-B (5) were isolated from the Bornean soft coral Xenia sp. The structures of these metabolites were elucidated on the basis of spectral analysis, NMR and HRESIMS. Compound 5 showed cytotoxic activity against ATL cell line, S1T.  相似文献   
5.
Molecular biology of mouse and chicken retroviruses had identified oncogenes and provided a revolutionary concept in understanding of cancers. A human retrovirus was established during 1980–1982 in linkage with a unique human leukemia, concurrently in Japan and USA. This review covers our efforts on the discovery of new retrovirus, Human T-cell Leukemia Virus Type 1 (HTLV-1), first introducing to a new class of retroviruses with a unique regulatory factors, Tax and Rex. Then it is followed by analyses of molecular interaction of the vial Tax with cellular machineries involved in the pathogenesis of Adult T-cell Leukemia (ATL). And then a probable mechanism of pathogenesis of ATL is proposed including recent findings on HBZ after our efforts.  相似文献   
6.
At high (150-1000%) stretching of a physical gel of a triblock copolymer a “butterfly”-type scattering pattern is observed with a pronounced scattering-free strip perpendicular to the stretching direction. The phenomenon is attributed to the cluster character of the physical network in the gel. Stretching brings endblock domains (junction points of the network) closer to each other in the direction perpendicular to the stretching and leads to formation of a layered structure. High connectivity of the network inside the clusters leads to saturation of the deformation within the clusters as manifested by the scattering-free region in the SANS pattern. © 1996 John Wiley & Sons, Inc.  相似文献   
7.
刘凌  苏燕辰  刘崇新 《中国物理》2007,16(7):1897-1900
This paper reports a new reverse butterfly-shaped chaotic attractor and its experimental confirmation. Some basic dynamical properties, and chaotic behaviours of this new reverse butterfly attractor are studied. Simulation results support brief theoretical derivations. Furthermore, the system is experimentally confirmed by a simple electronic circuit.  相似文献   
8.
In certain species of moths and butterflies iridescent colors arise from subwavelength diffractive surface corrugation of the wing-scales. The optical properties of such structures depend strongly on wavelength, incidence angle, and state of polarization of illuminating radiation, and the viewing angle. In this paper, we study the reflection spectra of the wings of the Morpho didius butterfly by simulating a double-layered model of a transverse cross-section comprised of the ground scale and the cover scale. Each layer contains a certain quasi-periodic arrangement of tree-like subwavelength microstructures. The simulation is done using a high accuracy nonstandard finite-difference time-domain (FDTD) method in two dimensions. We assume that the structure is made of a slightly lossy dielectric material. The wavelength dependence of the complex refractive index for the ground scale of Morpho didius is assumed to be similar to that of Morpho sulkowskyi. The complex refractive index in the latter case was obtained by comparing the computed reflection/transmission spectra with corresponding experimental measurements at normal incidence.  相似文献   
9.
A new type of self-complexed bis-crown ether containing two bis(p-phenylene)-34-crown-10 (BPP34C10) ether rings and two secondary ammoniums has been synthesized and characterized. The formation of these bis-self-complexes has been identified by NMR spectroscopy, mass spectrometry and X-ray analysis. The acid/base controlled movement of these bis–crown ethers can mimic a flapping butterfly.  相似文献   
10.
The purpose of this paper is to 1) describe the unique issues of voice patients, ages 21–55; 2) outline the knowledge and clinical skills that speech language pathologists should possess to deal with those issues; and 3) provide suggestions for promoting vocal longevity.  相似文献   
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