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我们将日本对虾进行实验室桶养作模拟内陆养殖试验。发现日本对虾可以顺利地养殖到体长5-7厘变,然后短人存活率急剧降低,这一现象与我们海边虾塘养殖所得到的结果极为一致,我们称之为“5-7”现象。 相似文献
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We studied two clones of Eucalypt urograndis hybrid (Eucalyptus grandis 9 E. urophylla), GR283 and GR330, grown in Tumkur district of Karnataka (India), and felled 5–6 years old three trees of each clo... 相似文献
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The ability to discriminate local stocks of Japanese anchovy Engraulis japonicus was assessed based on data from four elements (K, Na, P, and Sr) using an electron probe micro analyzer (EPMA) and data from
three elements (Ba, Mn, and Sr) using inductively coupled plasma mass spectrometry (ICP-MS) from the otoliths of 40 anchovy
(23.6–47.0 mm body length). Anchovy were caught at three sites (Aki-nada, Hiuchi-nada, and Osaka Bay) in the Seto Inland Sea,
and one site (Kuroshio extension) in the Pacific Ocean in 2002. In order to discriminate different spawning grounds, EPMA
data from the core portion (from core to 30 μm in the core-posterior axis) were used. Results showed that it was difficult
to discriminate between the Seto Inland Sea and the Pacific anchovy by EPMA data. Conversely, it was possible to discriminate
between the Seto Inland Sea and the Pacific anchovy by ICP-MS data from bulk otoliths. Our results showed that Mn contents
of otoliths using ICP-MS discriminate between spawning grounds most, and Ba and Sr discriminate less. The difference in elemental
compositions in anchovy otoliths between the Seto Inland Sea and the Pacific Ocean might be reflected by cumulative experienced
elemental composition of ambient sea water during life history between the Seto Inland Sea and the Pacific anchovy. 相似文献
16.
Interannual variability of the ecosystem of the Kii Channel, productive shelf water on the Pacific side of south‐western Japan, was analysed based on physicochemical environmental variables and abundance of major zooplankton taxa collected monthly for 12 yr from 1987 to 1999. The Kii Channel experienced both short‐term (i.e. 3–4 yr) cyclical changes and a long‐term (i.e. decadal) environmental trend. The short‐term variability was primarily associated with year‐to‐year differences in intrusion of subsurface, cold nutrient‐rich water along the bottom of the Kii Channel from the Pacific Ocean. When this bottom intrusion was intense, the Kii Channel experienced a cold, new production‐dominated ecosystem. The bottom intrusion, however, has become less intense in recent years, because of the closer proximity of the Kuroshio flow axis to the Kii Channel. Hence, there was a consistent trend towards warming and a regenerated production‐dominated ecosystem. In accordance with such environmental changes, the zooplankton community shifted towards more oceanic conditions; major herbivorous calanoids (i.e. Calanus sinicus, Paracalanus parvus (s.l.), Clausocalanus spp. and Acartia omorii) decreased, while carnivores (i.e. hydromedusae and Sagitta spp.) increased. The amount of total fish catch also decreased, while the catch of subtropical species increased. These findings lead us to conclude that the bottom intrusion from the Pacific Ocean plays a key role in determining the biological production in the Kii Channel. 相似文献
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Andrew S. Brierley Paul G. Fernandes Mark A. Brandon Frederick Armstrong Nicholas W. Millard Steven D. McPhail Peter Stevenson Miles Pebody James Perrett Mark Squires Douglas G. Bone Gwyn Griffiths 《Fisheries Research》2003,60(2-3):569-576
The autonomous underwater vehicle (AUV) Autosub-2 was deployed on eight missions ahead of RRS James Clark Ross in the northern Weddell Sea and in the Bransfield Strait, Southern Ocean, to assess avoidance of the research vessel by Antarctic krill Euphausia superba. The AUV was equipped with the same type of scientific echosounder as the research vessel (Simrad EK500 operating at 38 and 120 kHz) and measured the density of krill along transect acoustically (g m−2 wet mass) prior to the ship’s arrival. We hypothesised that if krill avoided the ship, perhaps in response to radiated noise, then the ship should detect less krill than the AUV which is known to have much lower noise levels than the ship. We were unable to detect any significant difference between the density of krill detected by the ship or the AUV, either at the transect level or at finer scales within transects. We conclude, therefore, that avoidance by krill of RRS James Clark Ross will not significantly bias acoustic estimates of krill abundance by this vessel. 相似文献
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舟山渔场人工鱼礁投放海域生态环境前期评估 总被引:18,自引:0,他引:18
根据2002年6-7月在舟山渔场朱家尖外侧开展人工鱼礁投放海域本底调查所获的海洋生物和海洋水文环境资料及以往有关文献中对该海域的调查资料,对朱家尖外侧拟投人工鱼礁海域的海水理化因子和海洋生物种类组成、数量分布和群落结构特征作了较详细的分析研究,以评估该海域是否适于投放人工鱼礁.结果得知:该海域底质为粉砂质粘土,浮游生物种类和数量及底栖生物种类和数量较多,水深为14~19m,温、盐度季节变化明显、透明度较高、水色相对较清,水质绝大多数指标符合国家一、二类水质标准,海域适合沿岸岛礁性鱼类如石斑鱼、褐菖、鲈鱼等的栖息生长,历史上渔业资源丰富,也无工厂废水排放,不会对海洋生态环境产生重大污染,因此,可以为良好的投放人工礁之场所. 相似文献
19.
智利外海渔场竹筴鱼资源分布特征 总被引:13,自引:0,他引:13
根据在智利 2 0 0海里专属经济区外海的渔场周年探捕调查 ,对智利竹鱼 (Trachurusmur phyi)单位努力量渔获量 (CPUE)的构成和季节变化及其资源分布特征进行了初步探讨。结果显示 ,竹鱼在智利外海分布广 ,30°~ 43°S ,78°~ 87°W海区均可形成拖网作业渔场。南半球冬季竹鱼密集分布区较偏南 (38°~43°S) ,8月密集分布区向北偏移至 35°~ 40°S,春季鱼群继续向北洄游至 30°~35°S ,并开始分散索饵 ,集群性较差 ,到翌年秋季再集群向南洄游 ,在 38°~ 43°S ,78°~ 85°W形成越冬场。CPUE以冬季最高 ,春、秋季次之 ,夏季最低。冬季以 6月份平均CPUE最高 ,达 1 5 .1 8t/h ,夏季以 3月份平均CPUE最低 ,仅 1 .1 2t/h。 相似文献
20.
CHEN Yan YUAN Chang-chun CHEN Xiao-ting School of Life Science Technology Zhanjiang Normal University Zhanjiang 《(《农业科学与技术》)编辑部》2008,(4)
[Objective] The aim of this study was to provide the theoretical basis for variety identification of carambola and pomiculture.[Method] The molecular structure of vessels in stem secondary xylem from three carambola varieties of Malaysia 8,Misi and Malaysia B17 were studied by cell image analysis system and microphotography.[Result] The molecular structure of vessels in stem secondary xylem from carambola was as follows:the first type had tails in two ends,the second type had tail in one end,and the third type had no tails in two ends.The average length of vessel elements was from 328.88 to 366.09 μm,while its average width was from 44.61 to 52.43 μm.Most of the end wall was simple perforation plates,while the alternate-opposite pitting was the major forms of pitting.[Conclusion] Most characteristics of vessel elements from carambola were evolutionary characters of vessel elements in the process of phylogeny,but there were more primitive characters,for example,both two ends of vessel had tails or just one end had tail,and end wall was inclined.The molecular structure of vessel from carambola was in accordance with its ecological adaptability,and the growth characteristics of different varieties were also in accordance with the difference of molecular structure of vessel. 相似文献