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21.
A. Ça?lan Karasu Benli Aylin Sepici-Dincel Duygu ?ahin 《Pesticide biochemistry and physiology》2007,88(3):296-299
The acute 96 h LC50 of (2,4-dichlorophenoxy)acetic acid (2,4-D), a widely used agricultural herbicide, was determined on crayfish (Astacus leptodactylus Esch. 1823). Crayfish of 23.5 ± 1.49 g mean weight and 9.6 ± 0.21 cm mean length were selected for the bioassay experiments. The experiments were repeated three times, in 10 L tap water. The data obtained were statistically evaluated by the use of the E.P.A computer program based on Finney’s probit analysis method and the 96 h LC50 value for crayfish was calculated to be 32.6 mg/L in a static bioassay test system. 95% lower and upper confidence limits for the LC50 were 15.10-327.16. In conclusion, 2,4-D is highly toxic to crayfish, a non-target organism in the ecosystem. Water temperature was 23 ± 1 °C. Behavioral changes of crayfish were recorded for all herbicide concentrations. 相似文献
22.
近几年,种养结合的高产高效模式很多,这不仅是当前渔（农）业结构调整中的一项新举措,也是渔（农）民增收的又一条好门路。2009—2010年,金湖县水产技术推广站以渔业科技入户“民心工程”为依托,在闵桥镇荷花荡养殖示范户丁济红的107×667m^2藕塘内进行套养龙虾技术推广试验,取得了河藕、龙虾高产高效双赢的喜人实绩,受到了当地渔（农）民的欢迎。现将主要技术方法总结以供参考。 相似文献
23.
盐度和时间对运输克氏原螯虾虾苗影响的模拟研究 总被引：2，自引：0，他引：2
克氏原螯虾虾苗在不同盐度条件下运输的模拟研究结果表明:在运输时间相同的情况下,在0%～0.4%盐度范围内,NaCl和Na2SO4处理虾苗的死亡率都随着盐度的提高而降低,之后随着盐度的增大,死亡率开始上升;在盐度相同的情况下,NaCl和Na2SO4处理虾苗的死亡率均随着运输时间的延长而增加;NaCl和Na2SO4处理组虾苗在饲养1周后的成活率明显高于对照,2种盐处理均在盐度为0.4%时的模拟运输死亡率最低,且成活率也最高;在运输时间相同和同等盐度条件下,NaCl组虾苗的运输死亡率和饲养1周后的成活率均好于Na2 SO4组。 相似文献
24.
污染水域克氏鳌虾体内重金属选择性富集研究 总被引：2，自引：0，他引：2
采用原子吸收分光光度法测定了生长于重金属重度污染环境下的克氏鳌虾体内及生长水域的水样、底泥等样品中Zn、Cu、Cd、Pb等重金属含量。结果表明:水样中Zn、Cd、Pb含量分别是地表水环境质量Ⅲ类标准的2.73、33和11.6倍,Cu含量高于I类而低于II类水标准;底泥中Zn、Cu、Cd、Pb含量分别是江西省水体底泥重金属平均背景值的20.5、12.8、221和11.9倍;克氏鳌虾体内Zn、Cu含量平均值分别是国家食品卫生限量标准的19.5和2.1倍,而Cd、Pb在所有样虾体内中均未检出。克氏鳌虾对重金属可能存在选择性富集机制。 相似文献
25.
Muzaffer Mustafa Harl&#x;o
lu 《Aquaculture (Amsterdam, Netherlands)》2004,230(1-4):181-187
The only native crayfish species in Turkey, Astacus leptodactylus, is widely distributed in lakes and ponds in many parts of the country. Its distribution area was considerably expanded in Turkey after 1985 because of its commercial importance and declined catches from traditional good fisheries. Although consumption of A. leptodactylus has always been very low in Turkey, it was exported to western Europe until 1986. Due to over-fishing, pollution and a disease (crayfish plague), the total production decreased dramatically to 200 from 5000 tonnes annually. In recent years (1991–1998), there has been a gradual increase in the production of crayfish in Turkey from 320 to 1500 tonnes, but plague is still present. 相似文献
26.
Huahua Du Zirong Xu Xiaofeng Wu Weifen Li Wei Dai 《Aquaculture (Amsterdam, Netherlands)》2006,260(1-4):39-43
In order to investigate whether protein structure has an effect on protective effect of envelope protein of WSSV, VP28 protein was expressed both in Escherichia coli (pET-VP28) and insect (BmN) cells (BmNPV-VP28). The baculovirus (BmNPV) expression system was used to obtain correctly folded VP28 protein. Procambarus clarkii crayfish were intramuscularly injected with lysates of cells infected with recombinant pET-VP28 and BmNPV-VP28, respectively, and then challenged by intramuscular injection of WSSV to assess the duration of protection. The crayfish injected with BmNPV-VP28 showed generally lower mortality rates when compared to crayfish injected with pET-VP28, resulting in relative percent survivals of 92% and 39%, respectively, when compared to the control groups injected with empty vectors BmNPV and pET-30a. These results showed that VP28 protein produced in BmN cells gave much better protection than VP28 protein produced in E. coli. 相似文献
27.
淡水小龙虾的综合利用 总被引：1，自引：0，他引：1
淡水小龙虾不仅有很高的营养价值,还有很高的经济价值,但长期以来人们对其综合利用重视不够,利用程度和利用水平都比较低。对淡水小龙虾综合利用的现状进行了综述,以期掌握其研究动态,指导生产。 相似文献
28.
《Journal Of Applied Aquaculture》2013,25(3):83-90
Abstract Red claw crayfish, Cherax quadricarinatus, are perhaps the first tropical species of crayfish to be cultured commercially. Culture traits and high market value could allow semi-intensive culture. Feeding strategies used in extensive crayfish ponds in temperate climates may not be the most appropriate for semi-intensive culture systems where year-round growth is possible. The following study was conducted to evaluate differences between using a pellet-based system versus a pellet-plus-forage-based system. The study was conducted in 14 0.3-ha ponds on a commercial farm in Ecuador. Juvenile red claw (1-2 g) were stocked into all ponds at a rate of 4/m2. All ponds received pelleted shrimp rations at a rate of 3% per day. Seven ponds also received dried hay at a rate of 100 kg/ha/mo during the 3-month study. At harvest, red claw weights were similar (30-34 g), but survivals were significantly higher in ponds receiving pellets and hay (65%) than in ponds receiving pellets only (50%). Yields in pellet-fed ponds averaged 594 kg/ha, while red claw receiving pellets plus forage averaged 889 kg/ha. The addition of dried forage was thought to provide a larger variety of natural food organisms throughout a greater area of the pond bottom and provided additional substrate for dispersal and hiding. Addition of grasses from outside the pond is recommended over production of grasses grown within the pond. 相似文献
29.
Pectin‐based pellets for crayfish aquaculture: structural and functional characteristics and effects on redclaw Cherax quadricarinatus performances 
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下载免费PDF全文 Pectin is a promising candidate to be employed as binder for manufacturing pellets for crayfish feeding. In this study, the gelling properties of different types of pectin and their effects on Cherax quadricarinatus performances have been analysed. Pectins with different degree of esterification from apple and citrus were screened to select those with the best gelling properties to be employed in pellet manufacturing. Three pectins were selected: low esterification degree apple pectin (LEAP), low esterification citrus pectin (LECP) and high esterification degree apple pectin (HEAP). Scanning electron microscopy analysis, nutrient leaching and water uptake indicated that LEAP showed the best aggregating properties, followed by LECP and HEAP pellets. Cherax quadricarinatus performances were affected by the pectin type, with redclaw fed LEAP pellets showing the highest (P < 0.05) growth rate and amylase activity (P < 0.05) in the gastrointestinal tract. Altogether these results indicate that LEAP can be considered an excellent binder for feed pellets due to its gelling properties and its efficacy to improve growth and stimulation of digestive enzyme activity. 相似文献
30.
寻求生态高效水产养殖新模式对于素有“鱼米之乡”的江苏兴化市水产养殖业的发展具有重要意义。本研究设置了河蟹与小龙虾混养、河蟹与青虾混养和河蟹单养模式的3种不同养殖模式，探讨不同河蟹养殖模式下的产量、产值及成本利润率的差异及其原因。结果表明，河蟹与小龙虾混养模式下病虫草害发生较少，经济效益最好（4515元/667m2），成本利润率最高（82％）；其次是河蟹与青虾混养模式；河蟹单养模式下最低。笔者认为河蟹与小龙虾混养这一生态养殖新模式符合当前水产养殖转型升级、绿色和高质量发展的需求，可在兴化市垛田街道及周边地区推广。 相似文献