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南黄海和东海浮游生物群落的初步探讨 总被引：10，自引：5，他引：10
南黄海和东海位于中国东部的陆架上,这个区域受江河迳流、大陆沿岸流、黄海冷水和黑潮水的影响,明显地反映出其水文、化学要素、浮游生物的分布都比较复杂.如果仅从浮游生物组成看,有暖温带的近海种,有半咸水河口种,有沿岸低盐种;也有外海热带种.它们构成了浮游生物各自的群落分布区,在群落之间由于水团的水平和垂直方向不同程度的混合,存在着一个群落交汇区.群落及其交汇区具有相对的稳定性,但随季节而有变化.本文根据1960年和1971年对南黄海和东海(东经127°以西、北纬27°-34°)进行渔场环境调查时,所获得浮游生物的样品,经分析后提出以下的初步探讨. 相似文献
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用随机扩增多态DNA(RAPD)技术对长兴岛刀鲚(Coilia ectenes)38个个体的遗传多样性进行了检测,从40个随机引物中筛选出13个对刀鲚的DNA进行扩增,结果为:13个引物共检测到112条清晰且重复性好的条带,分子质量在200~2000 bp之间,其中多态位点为74个,占66.07%;群体的Shannon多样性指数为0.3164,Nei基因多样性指数为0.2075,结果表明中国刀鲚遗传多样性处于较高水平。刀鲚成熟年龄早,对产卵条件要求不甚严格,产卵率和孵化率都比较高,具有较强的种群恢复能力;另外,由于长江中下游和湖泊刀鲚的捕食者和饵料竞争者的减少,客观上为刀鲚提供了良好的繁殖和幼鱼索饵条件,因此,结合刀鲚自身的生物学特征及生活环境特点,采取合理的保护和管理措施,中国刀鲚资源有望得到恢复。 相似文献
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The South Huanghai Sea and the East China Sea lie on the east continental shelf ofChina. These areas are generally under the effects of river, coastal currents, and coldwater in the Huanghai Sea, as well as the branches of Kuroshio. Therefore, obviously, thephysical oceanography, chemical elements and plankton distribution in these areas areconsiderably complicated. As for plankton composition, there are temperate neriticspecise, brackish water and estuarine species, coastal species and also tropical pelagicspecies. Each community of the plankton occupies a distributional area of its own.Among the communities there exists a transitional area caused by horizontal andvertical mixing of water masses which effect this area in different degrees. All commu-nities and the transitional area are more or less relatively stable, except for seasonal varia-tion. 相似文献
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地理课堂活动是现代地理课堂的重要组成环节,其合理实施能在一定程度上弥补传统地理课堂缺失的生活性与实践性,也能有效培养学生的地理核心素养.笔者通过文献调查法和问卷调查法,借鉴前人经验,总结了地理课堂活动的新内涵,对活动类型进行了重新分类,从教师和学生两个角度分析得出当前初中地理课堂活动的实施现状,并提出对应的改进措施,以期用更加科学的思维方式推动地理教学的发展. 相似文献
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Fish communities in a (third-order) intertidal creek in Dongtan marsh in the Changjiang (Yangtze) River estuary were investigated
seasonally for one year. A total of 1 996 fish specimens (10 967.8 g) comprising 26 species and 15 families were collected.
Abundances of fish communities in the intertidal salt marsh creek were primarily dominated by Boleophthalmus pectinirostris (19.8%), Collichthys lucidus (18.6%), Periophthalmus magnuspinnatus (18.2%), Liza haematocheilus (17.9%), and secondarily by Mugilogobius abei (8.5%), L. carinatus (7.2%), Odontamblyopus lacepedii (4.3%), and Acanthogobius ommaturus (3.9%); another 18 species were present only occasionally. Non-MDS ordination and SIMPER analysis indicated that there were
two fish communities in the intertidal salt marsh creek. In spring, the communities were dominated by B. pectinirostris, P. magnuspinnatus, C. lucidus and M. abei; in summer, autumn, and winter by L. haematocheilus, L. carinatus, A. ommaturus and O. lacepedii. Some species showed strong habitat selection; L. carinatus and P. magnuspinnatus were distributed mainly in the upper and middle creek, while B. pectinirostris, M. abei and O. lacepedii inhabited the middle and lower creek. The study indicated that the salt marshes of the Changjiang River estuary are an important
nursery and feeding habitat for many fishes and should be protected. 相似文献
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燃料油、苯酚和硫化钠对新月菱形藻生长繁殖及叶绿素α含量的影响 总被引：1，自引：0，他引：1
苯酚对新月菱形藻(Nitzschia closterium)的毒性最大,20~#燃料油次之。硫化钠组最大比生长率随浓度的增高而增大。20~#燃料油、苯酚和硫化钠影响其生长的最低觉察效应浓度一未觉察效应浓度(LOEC—NOEC)范围分别为32.00—3.20mg/L,3.20—1.00mg/L,和0.320—0.100mg/L;苯酚影响其叶绿素a含量的216h-EC_(50)为6.739±0.003mg/L,20~#燃料油影响其细胞分裂繁殖的144h-EC_(50)为46.13±1.01mg/L,高浓度燃料油抑制新月菱形藻的生长繁殖及叶绿素a含量,低浓度的则刺激其生长繁殖。 相似文献
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随着我国改革开放的深入发展,社会经济的需要以及人们对水产品的强烈需求和食品结构的改善,当前要求保护和改善渔业水域水质环境的呼声日益强烈和紧迫。这主要是近年来随着我国工业、农业等各项事业的迅速发展和城市居民的急剧增加,工业废水和城市污水大量排放等因素综合结果,导致许多江、河、湖、海的渔业水域遭污染,从而对海、淡水养殖 相似文献