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In this paper, the morphological characters of eggs and larvae ofSardinella aurita (Cuvier & Valenciennes), its spawning ground, spawning seasons and spawning conditions have been studied.
Sardinella aurita likes to breed in the upwelling area and selects the Waixie fishing ground as its main spawning ground. The months from February
to September are its spawning seasons, reaching its peak in April. In the main spawning ground, the temperature of the surface
layer was found to be 24.4–25.2°C, the salinity 33.87–34.07%. and the depth of water between 34–60m.
The distribution of the larvae is closely related to the distribution of plankton, the path of migration of adult fish, and
the current direction of the water system.
In order to protect fishery resources, it is necessary to prohibit catching the spawning fish in the Waixie fishing ground
in April, and the catching of immatures from March to June.
This paper was published in Chinese inOcean. Limn. Sinica
14(3): 240–248, 1983. 相似文献
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本文首次报道1987年11月至1988年11月在闽南-台湾浅滩渔场采获的9种叶状铒1鳗,它们分别属于3个科;鸭嘴鳗科3种,锯犁鳗科1种,蛇鳗科5种。文中描述、比较了研究叶状仔鳗的主要形态特征。 相似文献
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九龙江口鱼类浮游生物的生态 总被引:3,自引:3,他引:3
1987年3月到1988年2月在九龙江口的5个固定站位上,逐月进行鱼卵和仔,稚鱼调查的资料。结合1983年至1984年的鉴定资料进行分析,结果表明,该海区的鱼类生态结构系由淡水,半咸水,沿岸和海水鱼类等4种生态类型组成。鱼类主要产卵期为3-9月,盛期为5-8月。鱼卵数量以河口上游最多。种数则以河口下游较多。仔,稚鱼相对集中于河口中游,其数量和种数均为最多。在九龙江口放流,增殖或引进鱼类新种成功的机 相似文献
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中国西北干旱区土地沙漠化敏感性时空格局 总被引:14,自引:1,他引:13
土地沙漠化敏感性评估是沙漠化监测的重要内容之一,也是研究如何防止和治理沙漠化的重要课题。本文以中国西北干旱区作为研究区,利用遥感技术和GIS空间分析技术为支撑,通过构建“土壤—地形—水文—气候—植被”沙漠化敏感性综合评价指标体系,并借助空间距离模型计算了沙漠化敏感性指数,进而定量评估2000年、2005年、2010年和2017年西北干旱区土地沙漠化敏感性的时空演变特征,在此基础上引入地理探测器等方法对其主要驱动因素进行了深入分析。研究结果表明:① 地形、土壤、气候、植被和水文等5个方面相互影响,彼此制约,共同构成中国西北干旱区沙漠化敏感性分布和变化的本底条件;② 西北干旱区沙漠化敏感性总体上呈现周边低、内部高的分布特征,低敏感区主要分布在阿尔泰山、天山、昆仑山、阿尔金山和祁连山等地,而高敏感区则主要分布在准噶尔盆地、塔里木盆地和内蒙古高原等大部分地区,包括塔克拉玛干沙漠、巴丹吉林沙漠和腾格里沙漠腹地。沙漠化敏感性的空间分布具有显著的区域性,高敏感区和低敏感区界限分明、分布集中;③ 从时空演变看,2000年以来沙漠化敏感性变化以稳定型占据主导,而整体上敏感性表现为缓慢降低趋势,说明潜在沙漠化区域逐年减少,区域沙漠化治理工作取得了一定成效;④ 西北干旱区的各驱动因素中,土壤及气候起直接作用,是最主要的影响因素,而植被是改变沙漠化敏感性最活跃、最基本的因素。除此之外,地形的分布和水文的变化对沙漠化敏感性起到一定的限制作用,而社会经济因素是影响区域沙漠化敏感性最为快速的因素,且经济发展对促进区域沙漠化敏感性的增长作用有逐渐加强的趋势。从整体来看,中国西北干旱区土地沙漠化得到了有效遏制,沙漠化治理工作取得了积极成效,但在全球气候变化加强和社会经济发展进入新常态的大背景下,中国沙漠化监测评估和治理工作仍然任重而道远。 相似文献
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中国陆地生态敏感性时空演变特征 总被引:5,自引:0,他引:5
生态敏感性作为评价区域生态环境问题的重要指标之一,对区域的生态治理与管理工作具有重要意义。本文从自然生态系统、自然—社会复合生态系统、社会生态系统等视角选取生物多样性、水热环境、土壤盐渍化、土地荒漠化、土壤侵蚀和人类干扰6个指标,运用全排列多边形图示指标法对2000—2018年间中国陆地生态敏感性进行计算,并运用格网编码法对其时空演变特征进行分析。研究结果表明:① 2000—2018年间中国陆地生态敏感性总体稳定,生态敏感值稳定在0.33~0.34之间;但得益于21世纪以来中国实施了一系列生态环境治理与预防工作,敏感值在2000—2018年间持续下降,表明中国陆地生态敏感性状况正在逐渐好转。② 中国陆地生态敏感性空间异质性显著,呈现出“东低西高、南低北高”“城区高、郊区低”的空间分布格局。中国西部区域和北方区域自然环境恶劣,生态自我调节能力较差,易受外界因素的影响,而人类聚居区生态自我调节能力虽然较强,但由于人类活动强度较大,其敏感性反而较高。③ 中国陆地生态敏感性受土壤(地)环境因素影响较大,但人类干扰因素影响力也在逐年递增,这表明在经济快速发展的同时,中国的生态环境保护与治理工作仍然任重道远。 相似文献
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Wei Wei Guo Zecheng Shi Peiji Zhou Liang Wang Xufeng Li Zhenya Pang Sufei Xie Binbin 《地理学报(英文版)》2021,31(1):46-68
Sensitivity assessment is useful for monitoring land desertification.Research into how to prevent and control desertification is also important.In the arid region of northwest China,desertification is becoming worse and is a serious problem that affects local sustain-able development.Based on remote-sensing and geographic information system technology,this study establishes a"soil-terrain-hydrology-climate-vegetation"desertification sensitivity comprehensive evaluation system to reflect the spatiotemporal changes of land desertifica-tion,and proposes a spatial distance model to calculate a desertification sensitivity index.The spatiotemporal change characteristics of land desertification sensitivity in northwest China are quantitatively assessed from 2000 to 2017.Moreover,the main driving factors are ana-lyzed using the geographical detector method.The results show the following.(1)Terrain,soil,climate,vegetation and hydrology affect and restrict each other,and constitute the back-ground conditions of the distributions and changes of sensitivity to desertification in northwest China.(2)Desertification sensitivity generally displays a low distribution characteristic on the periphery of the area and a high one in the interior.The low-sensitivity regions are mainly in the five major mountain ranges(Altai Mountains,Tianshan Mountains,Kunlun Mountains,Altun Mountains and Qilian Mountains),while the high-sensitivity regions are mainly in re-gions such as the Junggar Basin,the Tarim Basin and the Inner Mongolia Plateau,as well as the Taklimakan Desert,Badain Jaran Desert and Tengger Desert.The spatial distribution of desertification sensitivity is obviously regional,and the high-and low-sensitivity regions have clear boundaries and a concentrated distribution.(3)With regard to spatiotemporal evolution,changes in desertification sensitivity since 2000 have been predominantly stable,and the overall sensitivity has displayed a slowly decreasing trend,indicating that potential desertifi-cation regions are decreasing annually and that some achievements have been made in the control of regional desertification. (4) Soil and climate play a direct role in the driving factors of desertification in northwest China, and these have been found to be the most important in-fluential factors. Vegetation is the most active and basic factor in changing the sensitivity. In addition, topography and hydrology play a role in restricting desertification changes. So-cio-economic factors are the most rapid factors affecting regional desertification sensitivity,and their impacts tend to be gradually increasing. In general, desertification has been effec-tively controlled in northwest China, and positive results have been achieved in such control.However, against the backdrop of intensified global climate change, increasingly prominent human activities and new normals of socio-economic development, the monitoring, assess-ment and control of desertification in China still have a long way to go. 相似文献
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