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871.
872.
The Changjiang (Yangtze) Estuary is located in the East China Sea shelf with shallow water. Affected by the tide mixing and the runoff of the Changjiang River and the Qiantang River, the turbidity is very high. Generally, the water-leaving radiance is high in the turbid water because of the large particle scattering. Based on the in-situ data and ocean color remote sensing data of SeaWiFS, it was found that there was a black water region with the normalized water-leaving radiances less than 0.5 mW/(cm2·μm2·... 相似文献
873.
Bernerd Fulanda Cosmas Munga Jun Ohtomi Melckzedeck Osore Robinson Mugo Md. Yeamin Hossain 《Ocean & Coastal Management》2009,52(9):459-466
The current study was carried out over a period of one year to characterise the coastal migrant fishery of Kenya. The study looked at gears and vessels used, and ownership, demographic factors including ages of the fishers and family sizes, migrant activity and resource conservation at two main fishing villages in Kenya; Vanga and Mayungu in the south and north coasts, straddling at 4.663°S and 39.215°E and 3.214°S and 40.135°E respectively. Further, the fishers were categorised with regard to fishing, gear and vessel operation and trade, and evolution upon entry into the fishery was also assessed in order to define fisher-stake in the fishery for resource management and conservation planning. Structured questionnaires were used to interview the fishers, and data and information recorded from 1018 fishers during the survey. Migrants accounted for over 63% of the fishers in the two study sites, with majority of the fishers lying in the 15–45 year age bracket. Dependence level averages at 4–6 person families per fisher. Entry to the fishery was mainly at seamen level, progressing to fishermen and finally to fish dealers (tajiris), with the latter holding >62% capital in the fishery. Resource management in the fishery was low and only 10% of the fishers were active participants in marine conservation and community beach management issues. Fisher migrations were mainly monsoon season-linked (>58%) although social factors such as family location determined to a great extent the expanse of the migrations. The revival of fisheries cooperatives and active participation in community resource management and conservation groups is envisaged as the key to the sustainability of both the marine resources and the economies associated with this high mobility, cross-border fishery. 相似文献
874.
斜带石斑鱼不同地理群体遗传变异的微卫星分析 总被引:1,自引:0,他引:1
筛选5时可分析引物对斜带石斑鱼(Epinephelus coioides)台湾群体和广东群体的DNA多态性进行分析.根据电泳检测结果,平均每个引物获得4.2个等位基因,未发现群体的特异位点.获得2个群体平均观测杂合度(H_o)分别为0.672 1和0.682 6,平均期望杂合度(H_e)分别为0.647 9和0.544 4,两群体间的遗传分化系数(F_(ST))为0.011 0.统计结果表明,2个群体有着较高的遗传变异性,群体间的遗传分化程度处于多数海水鱼类的平均水平. 相似文献
875.
876.
877.
2004年7~8月在台湾浅滩周边水域进行了两个断面的水体悬浮物浊度、叶绿素a荧光调查,通过对该区域悬浮物质浊度、叶绿素a荧光的夏季分布变化特征研究,结合水文相关要素分析,初步揭示了区域海洋沉积和再悬浮过程对悬浮体浊度、叶绿素a荧光分布的影响。指出悬浮物质浊度在近岸与陆架外缘主要受再悬浮作用影响,而浅滩区再悬浮作用不明显:在陆架外缘区浮游植物的聚集作用对浊度有一定的贡献作用,而近岸区则不明显。 相似文献
878.
879.
Yuxiang Ma Guohai Dong Marc Perlin Shuxue Liu Jun Zang Yiyan Sun 《Ocean Engineering》2009,36(8):595-604
This paper considers higher-harmonic forces due to wave focusing on a vertical circular cylinder. A series of experiments has been conducted in a wave flume. The first six-harmonic components of the measured wave forces are analyzed using the scale-averaged wavelet spectrum. It is noted that due to the transient nature of focused (freak) waves, Fourier analysis would not provide equivalent information to that gleaned from the analyses used herein. The results for the experiments with very steep wave crests show significant amplitudes at the fourth and fifth harmonics. These harmonics exhibit amplitudes that are the same order as the second harmonic, but much larger than those of the third harmonic. The wavelet-based bicoherence is used to detect the quadratic nonlinearity of the measured forces. And the bicoherence spectra reveal the primary mathematical reason for the existence of the striking amplitudes of the fourth and fifth harmonics: the interaction between the lower-harmonic components couple more strongly with the fourth and fifth harmonics, thus the fourth and fifth harmonics glean more energy than those of the third-harmonic components. However, the physical explanation for this remains elusive. 相似文献
880.
赤道潜流变化及其与ENSO的关系 总被引:4,自引:0,他引:4
应用TOGA/TAO实测海流和SODA全球海洋再分析资料,分析研究了热带太平洋赤道潜流的变化特征及其与ENSO循环的关系,初步探讨了赤道潜流变化对两种不同类型(中部型和东部型)ENSO事件的影响。对赤道潜流距平场的EOF分解表明,第一模态为"东太平洋潜流模态",特征向量主要反映东太平洋赤道潜流的变化情况;第二模态为"中太平洋潜流模态",特征向量主要反映中太平洋赤道潜流的变化情况;这两个主要模态基本可以反映赤道潜流距平场的主要信息。这两个模态对应的时间系数有明显的年际变化特征,并且与NINO指数都有较好的负相关,最大相关均通过99.9%的信度检验。相关分析表明潜流第一模态的变化滞后于NINO指数变化,而第二模态的变化则提前于NINO指数变化,即ENSO事件对东太平洋赤道潜流的变化有一定影响,而中太平洋的潜流变化又会对ENSO事件产生影响。通过个例分析表明,中太平洋赤道潜流的变化对两种不同类型ENSO事件的发生有重要影响。在东部型ENSO事件发生前,中太平洋赤道潜流增强,这样西太平洋暖池的异常海温在潜流的引导下快速向东传播,直接到达东太平洋形成东部型ENSO事件;中部型ENSO事件发生前,中太平洋赤道潜流明显减弱,西太平洋的异常海温不能迅速东传速,在中太平洋堆积上升到达海面,使得中部型ENSO事件爆发。 相似文献