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1.
在室温条件下分三组培养发头裸腹溲酵母液为培养液，设Ａ组为对照组，Ｂ组每天更换１０ｍｌ培养液，Ｃ组始终不给予光照，结果是Ｂ组食物浓度过高，种群增长受较明显的抑制，表现为个体数少，寿命短，怀卵期延长，培养期间不给光照的Ｃ组，其种群增长也不及对照组。 相似文献
2.
采用种群累积培养法,在控温３２℃条件下进行实验,观察在面包酵母中加入光合细菌和维生素Ｃ培养萼花臂尾轮虫的效果。结果表明,光合细菌对该轮虫的种群增长有明显的促进作用。在酵母液中加入１％～１０％的光合细菌液（菌液的浓度为１０×１０８～１３×１０８ｃｅｌ／ｍｌ）,轮虫种群密度可增长４～５倍。维生素Ｃ的添加量在０．０２ｍｇ／ｍｌ时,对轮虫的种群增长有促进作用;在０．１ｍｇ／ｍｌ时,其促长作用显著;在本实验设计范围内,当浓度等于或高于０．５ｍｇ／ｍｌ时,由于极大地降低了培养液的ｐＨ值,导致轮虫死亡。 相似文献
3.
进行了稻草液和麦粒液培养草履虫的对比试验并进行了室外生产性培养试验。结果：稻草液效果好于麦粒液，稻草液浓度为１％草履虫分裂速度最快；培养液增氧，草履虫的分裂速度比不增氧快１．３倍；室外培养的产量与温度、光照、食物密切攸关。在室外遮光条件下，用１％稻草豆汁液（豆汁液为稻草液的１‰）培养草履虫的种群密度，平均每日增长２０２倍。 相似文献
4.
采用铜绿微囊藻为试验材料,将其经光限制(完全黑暗)胁迫处理7d,以光照强度为3000lx、光暗周期为12h∶12h的培养组为对照。然后解除光限制胁迫,在相同接种量和相同培养条件下,将处理组和对照组均置于3000lx光照条件下培养10d。试验过程中测定铜绿微囊藻的吸光度、细胞密度、叶绿素a和细胞内蛋白质含量等指标。在光限制胁迫过程中,处理组的藻液吸光度、藻细胞密度、平均相对生长率、细胞数净增长率、叶绿素a含量及藻细胞直径较对照组均显著降低,但藻细胞蛋白质含量显著高于对照组。在恢复光照10d的培养过程中,处理组的藻液吸光度、藻细胞密度、平均相对生长率、细胞数净增长率及叶绿素a含量较对照组均显著升高,而藻细胞直径和蛋白质含量与对照组差异不显著。试验结果说明铜绿微囊藻在光限制胁迫后具有明显的超补偿生长性能。 相似文献
5.
采用铜绿微囊藻为试验材料,将其经光限制(完全黑暗)胁迫处理7d,以光照强度为3000lx、光暗周期为12h∶12h的培养组为对照。然后解除光限制胁迫,在相同接种量和相同培养条件下,将处理组和对照组均置于3000lx光照条件下培养10d。试验过程中测定铜绿微囊藻的吸光度、细胞密度、叶绿素a和细胞内蛋白质含量等指标。在光限制胁迫过程中,处理组的藻液吸光度、藻细胞密度、平均相对生长率、细胞数净增长率、叶绿素a含量及藻细胞直径较对照组均显著降低,但藻细胞蛋白质含量显著高于对照组。在恢复光照10d的培养过程中,处理组的藻液吸光度、藻细胞密度、平均相对生长率、细胞数净增长率及叶绿素a含量较对照组均显著升高,而藻细胞直径和蛋白质含量与对照组差异不显著。试验结果说明铜绿微囊藻在光限制胁迫后具有明显的超补偿生长性能。 相似文献
6.
本研究表明在禽舍中加入枯草杆菌培养物可降低氨的排放。在试验１中,６５周龄Ｗ－３６母鸡分隔饲养于一封闭鸡舍内,分成２组,每组１８０只。饲料中不添加 ＤＢＳＣ为对照组,添加 ２％ＤＢＳＣ为试验组。在试验 ２中,２周龄肉用仔鸡３组饲养于笼内,每组２０只。１组对照,其余两组分别添加１％和２％的ＤＢＳＣ。试验表明,产蛋鸡产房内及鸡粪中氨气含量明显降低（Ｐ＜０．０１）。粪便发酵１、２、３、４、５、６、２４或４８ｈ后表明：ＤＢＳＣ可持续降低氨气的排放。实验 ２的结果表明, ＤＢＳＣ降低了肉鸡舍氨气的释放,但ＤＢＳＣ对粪中总氮量、尿酸盐氮和氨氮的含量无影响,而喂以１％ＤＢＳＣ的肉鸡对氮的利用效率提高,其血清尿酸盐氮含量减少。 相似文献
7.
本研究表明在禽舍中加入枯草杆菌培养物可降低氨的排放。在试验１中,６５周龄Ｗ－６母鸡隔饲养于一封闭鸡舍内,分成２组,每组１８０只。饲料中不添加ＤＢＳＣ为对照组,添加２％ＤＢＳＣ为试验组。在试验２中,２周龄肉用仔鸡３组饲养于笼内,每组２０只。１组对照,其余两组分别添加１％和２％ＤＢＳＣ。试验表明,产蛋鸡产房内及鸡粪中氨气含量明显降低（Ｐ〈０．０１）。粪便发酵１、２、３、４、５、６、２４或４８ｈ后表明： 相似文献
8.
不同藻类生长、繁殖的生态条件是不尽相同的利用球等鞭金藻（Ｉｓｏｃｈｙｓｉｓｇａｌｂａｎａ）与其污染藻－卵形小球藻（Ｃ．ｏｖａｌｉｓ）生态习性的差异，在培养过程中对藻液ＰＨ值进行人工控制，使其保持在球等鞭金藻生长的适宜范围之内，从而达到促进球等鞭金藻生长，控制卵形小球藻繁殖之目的。本文通过对３组污染程序不同的藻液的对比培养实验发现，在温度范围１７－１８．４℃，照度范围３０００－８０００Ｌｕｘ条件下， 相似文献
9.
方正银鲫原产地为黑龙江省方正县双凤水库，该鱼在分类上属鲤形目（Ｃｙ－ｐｒｉｎｉｆｏｒｍｅｓ），鲤科（Ｃｙｐｒｉｎｉｄａｅ），鲤亚科（Ｃｙｐｒｉｎａｅ），鲫属（Ｃａｒａｓｓｉｕｓ），鲫种（Ｃａｒａｓｓｉｕｓａｕｒａｔｕｓ），银鲫亚种（Ｃａｒａｓｓｉｕｓａｕｒａｔｅｓｇｉｂｅｌｉｏ）。方正银鲫与单性型银鲫只有雌鱼，没有雄鱼不同，它具有雌、雄两性，且两性的染色体数和核型都相同，是世界仅有的两性型三倍体银鲫种群，以营雌核发育繁殖后代。著名的异育银鲫便是利用方正银鲫作母本培育而来的。方正银鲫具有生长快、营… 相似文献
10.
滁州鲫是安徽省滁州市城西水库中的一地方性天然种群。研究表明，滁州鲫具有２种不同的染色体组型。Ａ型的染色体组型是３ｎ＝１６０＝３１ｍ＋２１ｓｍ＋４５ｓｔ＋６３ｔ，总臂数＝２１２；Ｂ型的染色体组型是３ｎ＝１５８＝３０ｍ＋２６ｓｍ＋４２ｓｔ＋６７ｔ，总臂数＝２１４。 相似文献
13.
When, in the 1980s, I became interested in the spermatology of fish under the light microscope, active spermatozoa were only visible thanks to their head presenting a sort of “tremor.” This situation was quite frustrating given the lack of possible information regarding the motor part called flagellum. We decided to apply simple technologies, including photography. Due to the high speed of the moving fish flagellum, the microscope illumination used a pulsed light strobe combined with a dark field microscope to record the flagellum image despite its small diameter (< 0.5 μm). Then came high-speed cinematographic microscopy up to 200 fps, as well as video cameras. At the end of the 1990s, an automatic moving object video tracking system began to be commercialized (CASA) with main advantages such as (a) a large number of cells tracked, which greatly improves statistics, (b) computer assistance allowing an automatic analysis that provides many motility parameters. Nevertheless, CASA systems are still unable to provide information about fish sperm flagella that move fast. During the 1990s, analog video camera technologies allowed acquisition of flagellum images with high resolution for detailed analysis. Since the 2000s, the use of high-speed video cameras allows the acquisition of images at a much higher resolution and frequency, up to 10,000 frames per second. Since it became possible to visualize the flagella in motion, a noble function was added to that of a propeller: that of a rudder with what a spermatozoon responds to specific signals delivered by the egg for its guidance. In the future, one can wish that an automatic flagella movement analyzer will become functional. This brief anthology puts forward the large amount of progress accomplished during past 40-year period about spermatozoa movement analysis, especially in fish. 相似文献
14.
汤河水库１９９７～１９９９年对库区野杂鱼的捕捞采用新的渔具渔法,３年间共捕获野杂鱼１８２３８０ｋｇ,获利９９．５万元,是水库渔业经济增长的重要方式。 相似文献
15.
1. Temporary ponds provide rich but unpredictable habitats for amphibians. Frogs, toads and newts have life cycles which are geared to the filling and drying-up of temporary ponds, and have evolved strategies for dealing with desiccation and short-term changes in pond quality. 2. Plasticity in development allows frogs and toads to adjust the rate of larval development according to the risk of pond desiccation. This may be achieved by increasing behavioural thermoregulation so that body temperature is raised in warm, shallow water. 3. As a pond dries up, increased crowding between amphibian larvae may result in increased competition, growth inhibition, and cannibalism. Large larvae may therefore survive at the expense of small larvae, but this may increase the chance of some reproductive success within the population as a whole. Conflicting selection pressures may maintain different breeding strategies within the same population. 4. Despite high fecundity, repeated breeding by adults, and developmental plasticity and cannibalism in larvae, many larval populations still suffer catastrophic mortality each year. Providing catastrophes do not occur more often than once per generation, the population may still persist. Should extinction occur at one pond, immigration of juveniles or adults from a neighbouring pond may ensure population continuity. Networks of ponds are therefore essential to maintain viable, self-adjusting metapopulations into the long-term. © 1997 John Wiley & Sons, Ltd. 相似文献
16.
通过浅析中国加入ＷＴＯ所带来不利影响和诸多有利条件，概述了渔业经济应如何知己知彼，扬长补短，充分发挥自有优势和利用“入世”后的有利条件，推动渔业经济健康发展。 相似文献
17.
This paper evaluates the implications of managing fisheries to achieve a B MEY target, or a biomass level that maximizes net economic returns in the fishery, and discusses the role of private ownership and the trade‐offs between economic and conservation benefits in this setting. The paper shows how a B MEY target can be used to: (i) determine relative employment and profitability measures; (ii) account for both the harvesting and processing sectors; and (iii) incorporate the interests of consumers and producers of fish. The profits–employment trade‐off of adopting a B MEY target vs. a traditional B MSY target is calculated using a model and data from the Western and Central Pacific tuna fisheries (WCPTF), while a generic bioeconomic model is constructed to show numerical values of B MEY from including processing and/or retail sectors and the consumer benefits of harvesting fish. For the WCPTF, results show that the long‐term gains per job lost from pursuing a B MEY target are worth several times the value of the average GDP per capita of Pacific Island Countries. The generic bioeconomic model shows that including a processing and/or retail sector, as well as measures of consumer benefit, lowers the B MEY target. However, there remains a broad range of parameter values for which B MEY is still greater than biomass at maximum sustainable yield, or B MSY. The paper also illustrates cases where B MEY > B MSY at different values of the price elasticity of demand, margins for processing and/or retail sectors and values of the discount rate. 相似文献
20.
A 45‐day feeding experiment was conducted to examine two levels of dietary choline chloride (CC) [0.6 and 1.2 g kg ?1 CC] against control (0.0 g kg ?1 CC) on the biological, biochemical composition and stress tolerance of postlarval (PL‐20) Marsupenaeus japonicus. The results showed improvements in some biochemical contents such as phosphatidylcholine (PC) and methionine (Met) as 0.6 and 1.2 g kg ?1 dietary CC significantly ( P < 0.05) increased both PC and Met contents of shrimp carcass more than those of the control group. The results also showed that supplemental (0.6 g kg ?1) choline could improve ( P < 0.05) PC/PE (phosphatidylethanolamine) ratio. Growth parameters of the shrimp group that received 0.6/1.2 g kg ?1 dietary CC showed a significant ( P < 0.05) improvement. In case of osmotic stress test, 0.6 g kg ?1 supplemented CC level showed significantly ( P < 0.05) longer LT‐50 (the lethal time needed to kill half of the population) than the other shrimp groups that received 0.0 and 1.2 g kg ?1 dietary CC levels. This study showed the efficacy of 0.6 g kg ?1 dietary choline to improve the osmotic tolerance of kuruma shrimp as well as growth, survival and biochemical contents of postlarval kuruma shrimp. 相似文献
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