共查询到19条相似文献，搜索用时 531 毫秒
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以日本白令海引进的咖啡金黄水母为亲本,通过人工繁殖的方法获得受精卵.在实验室培育条件下,对浮浪幼虫、螅状体、碟状体和水母幼体等多次变态发育过程进行了系统观察,描述了各发育阶段形态变化,首次报告了咖啡金黄水母的生活史.咖啡金黄水母为体外受精,卵为沉性,受精后6h内发育为浮浪幼虫,浮浪幼虫有明显的趋光性,在54 h内变态附着为4触手螅状体.螅状体能通过多种方式进行无性繁殖,于20℃横裂生殖,每个螅状体每次横裂产生8～21个碟状体,碟状体的数量和质量与横裂前螅状体的状态有关.合适的水流和充足的食物保证了碟状体在60 d内变态为伞径10cm的育成体.人工条件下,螅状体可长期保存,水母体能饲养8～10个月. 相似文献
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安朵仙水母在固着的无性繁殖螅状体和浮游的有性繁殖水母体间交替,其生活史中绝大多数环节并不是自发进行的,而是受特定的物理、化学或生物因素的影响。静止水流和雌雄个体间的交互作用对于产卵和受精是非常重要的,受精卵在64h内可经浮浪幼虫阶段变态为4触手螅状体。螅状体能通过单碟型横裂产生水母体,但对温度和光照要求严格。出芽生殖是螅状体无性繁殖的唯一方式,出芽率与温度关系最为密切。大多数碟状体在横裂的过程中生长出口腕,并在脱离螅状体12～24h内翻转为口腕向上、外伞向下的倒立形态。水母体可通过食物和体内的共生藻获得能量。人工条件下,螅状体可长期保存,水母体可以饲养两年以上。 相似文献
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重金属对海蜇螅状体的急性毒性试验 总被引：6，自引：0，他引：6
海蜇(Rhopilema esculenta Kishinouye)螅状体阶段在海蜇的一个生命周期中所经历的时间最长，即从十月初到翌年五月。在这段时间里，环境条件直接影响着螅状体的存活；保持螅状体能够正常生存，是在人工增殖海蜇资源中提高海蜇幼水母出苗量的重要环节。 相似文献
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莱州湾海蜇放流增殖效果的探讨 总被引：2，自引：0，他引：2
本文利用人工控温的方法,使人工培育的越冬螅状体比自然海域螅状体释放蝶状体的时间提前30～40d,继而培育成5～10mm的幼水母进行放流。用幼水母伞径之差异探讨海蜇放流增殖效果,是目前国内首次报道的最佳方法之一。 相似文献
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MS-222对鳊鱼麻醉保活运输效果的研究 总被引：2，自引：0，他引：2
为研究MS-222对鳊鱼保活运输的影响,分析比较了在不同质量浓度MS-222(0、20、40、60、80、100 mg/L和120 mg/L)、不同水温(2、7、15、20℃)和不同鱼水质量比(2∶1、1∶1、1∶3、1∶5)下鳊鱼的存活率,从而确定及筛选最佳的保活运输条件,并检测和分析在保活运输试验中水质指标和鱼体生化指标的变化和影响。试验结果显示,当MS-222质量浓度为60 mg/L、水温7℃、鱼水比1∶3时,保活时间最长,鱼体存活率最高;随着保活时间的延长,水体指标中氨氮含量、微生物、pH均呈上升趋势,而溶解氧水平则呈下降趋势;在鱼体指标中,肌肉中糖原、pH下降,乳酸含量上升;在血液指标中乳酸脱氢酶、谷草转氨酶、血糖、尿素和肌酐均显著增加(P<0.05),说明随着保活时间的延长,鱼体肝脏和肾脏组织代谢水平受到一定的影响,但其变化幅度均小于对照组。研究结果表明,在鳊鱼保活过程中可适当使用MS-222麻醉剂以延长存活时间和提高存活率。 相似文献
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Size-dependent predation on marine fish larvae by Ctenophores, Scyphomedusae, and Planktivorous fish 总被引：3，自引：0，他引：3
Size-dependent predation rates on marine fish larvae by the ctenophore Mnemiopsis leidyi , scyphomedusa Chrysaora quinquecirrha , and planktivorous fish Anchoa mitchilli were estimated via experiments in 3.2 m3 me-socosms. Predation rates on larvae of the goby Gobio-soma bosci were estimated in relation to 1) length of larval prey, 2) presence or absence of alternative < 1 mm zooplankton prey, and 3) a predator-prey interaction between the scyphomedusa and ctenophore. The consumption rate of larvae by the three predators generally declined as larval length increased. The ctenophore ate fewer (1.0 d-1 per predator) larvae than did the medusa (7.8 d -1 per predator) or bay anchovy (4.0 d -1 per predator), but it consumed larvae in all size classes tested (3.0–9.5 mm SL). Predation by bay anchovy and the medusa was more size-dependent: 3.0–5.0 mm larvae were most vulnerable. Fewer larvae were eaten by the ctenophore and bay anchovy when zooplankton alternative prey was available, but predation on larvae by the medusa was not influenced by alternative zooplankton prey. Consumption rate of fish larvae by the medusa was reduced 20–25% when the ctenophore was present as its alternative prey. An encounter-rate model was developed and its parameters estimated from the experimental results. Model simulations indicated that the relationship between larval size and vulnerability is dependent on size, swimming speed, and behavior of both predators and larvae, and that bigger or faster-growing fish larvae are not always less vulnerable to predation. 相似文献
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本研究测定了盐化幅度(3/d、6/d、9/d、12/d和15/d)、盐化速度(1、3、6、12和18 h/次)和盐化方式(前期盐化、中期盐化、后期盐化和间隔盐化)与凡纳滨对虾(Litopenaeus vannamei)仔虾生长发育、活力和存活率的关系。研究结果显示,不同盐化幅度、盐化速度和盐化方式均显著影响盐化标粗过程中仔虾的生长发育、活力和存活率(P<0.05)。综合考虑生长性能、苗种活力和存活率等因素,最适盐化幅度为3~6/d,在该盐化幅度范围内,仔虾存活率可达74.07%~78.83%;盐化幅度超过9/d时,仔虾存活率显著下降(P<0.05),其中,盐化幅度达到15/d时,存活率仅为43.37%。过快的盐化速度导致存活率和活力显著下降,盐化速度>1 h/次时,仔虾死亡率接近50%;随着盐化速度的放缓,仔虾生长速度加快,盐化速度为6~18 h/次时,生长速度维持稳定,日增重量为1.48~1.51 mg。在盐化方式方面,后期盐化和间隔盐化时,苗种的质量和存活率优于前期盐化和中期盐化,仔虾活力表现为间隔盐化>后期盐化>中期盐化>前期盐化。综合考虑,仔虾的最适盐化幅度为3~6/d,最佳盐化速度为6~12 h/次,后期盐化和间隔盐化更有助于仔虾保持较好活力和较高存活率。本研究通过探讨凡纳滨对虾苗种盐化标粗的最适盐化幅度、盐化速度和盐化方式,丰富了凡纳滨对虾高盐环境抗逆性研究,为凡纳滨对虾苗种的盐化标粗生产实践提供了理论支持。 相似文献
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观察研究了10个盐度梯度(7、12、17、22、27、32、37、42、47和52)对条纹锯鮨(Centropristis striata)仔鱼的活力、开口和摄食情况的影响,记录分析其在不同盐度条件下不投饵存活系数、开口率、摄食率及摄食强度等指标.结果显示,盐度对条纹锯鮨仔鱼的活力、摄食及存活有明显影响,其存活和摄食的适宜盐度范围为12-37,最适盐度范围为27-32.盐度低于12时,仔鱼存活率、开口率和摄食强度随盐度的降低而降低,盐度高于37时,仔鱼存活率、开口率及摄食强度则随盐度的升高而降低.不同盐度条件下,条纹锯鮨仔鱼SAI值的波动范围为0.034-6.401,盐度为12-37的实验组与7、42、47、52实验组的SAI值存在显著性差异(P＜0.05),盐度为32时,仔鱼的SAI 值最大,为6.041,SAI值与盐度之间符合三次曲线函数关系,其表达式为y=-5.894+1.155x-0.034x2+0.000x3,R2 =0.895,其中,y代表SAI,x代表盐度.盐度为7、42、47和52时,仔鱼的存活率均低于50％,盐度为52、47时,仔鱼在第3、4天存活率分别降为0.盐度为22、27、32时,培育至第5天,仔鱼的存活率均在80％以上.盐度在17-37范围内,仔鱼开口率为60％-85％,且仔鱼均能较好摄食,盐度为32时,仔鱼开口率达到最大值,为85％,仔鱼摄食亦达到最佳状态,摄食率为85％,8日龄仔鱼摄食强度为5.45个轮虫/尾. 相似文献
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Waterless live fish transportation is an alternative and promising transport strategy, which may reduce shipping costs, increase stocking density and improve survival of some species. Spotted sea bass is one of the most economically important marine fish in China. However, waterless transportation has not yet been studied on spotted sea bass. To explore the possibility of waterless transportation of spotted sea bass and its sublethal stress responses, the survival rate and dynamics of blood biochemical parameters were evaluated in the present study by preserving it under no water, less water and water (control) conditions for 9 hr. The serum biochemical parameters including total protein, cortisol, glucose, lactate, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total carbon dioxide (TCO2), creatinine, blood urea nitrogen (BUN), ammonia, superoxide dismutase (SOD) activity and malonaldehyde (MDA) were investigated. Results showed that the survival rates of fish in all groups gradually declined with time increasing. At the end of transportation, the survival rates in the control group, less‐water group and no‐water group decreased to 49.11%, 15.60% and 23.96% respectively. Significant changes were observed in several selected serum biochemical parameters, including glucose, lactate, ALT, TCO2, BUN and ammonia during simulated waterless transportation, which might negatively affect the physiological homeostasis of fish, leading to the high mortality in present study. In general, waterless transportation of spotted sea bass was possible, but it might be rather suitable for short time than long time. 相似文献
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Two rearing conditions, tank light-dimensions and diet, were tested in dusky grouper—larvae and juveniles—in order to improve larval rearing techniques for this species. Larvae reared in high-volume and fluorescent tubes showed the highest survival rate at 18 dph (17.67%, 16%). This might be due to a higher depth and less trapping area during surface death in high-volume tanks than in low volume. Besides, a 500-lx evenly distributed light with fluorescent tubes might improve survival rate at early stages rather than illumination with energy-efficient light bulbs (4.68%, 9.64%). Light bulbs created shaded areas with less illumination inducing low larval activity. First feeding was performed with minimum rotifer lorica width of 102?±?10.2 μm. No mixed diet was supplied. Throughout metamorphosis, stress shock syndrome appeared to be the main cause of mortality. Diet A showed best growth and survival (4.1–7.36%) during this period probably due to its high HUFA content (9.5%). Contrary to what was observed during first stages, groupers showed best performance with lower illumination. Cannibalism was observed during this period in all culture conditions. 相似文献
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The behaviour of individual abalone in a population is known to vary, and higher levels of activity are linked to better survival rate and faster growth. Considering that continuous illumination at night may cause stress to the abalone which would affect their behaviour over time, in this study observations were made under brief and minimal illumination. The observation lasted for 30 days. The relationships between activity traits were analysed in juvenile Haliotis discus hannai Ino, such as forage frequency, duration and trajectories; flow preference; and aggregation size. The aim was to identify an indicator of the abalone activity status, with the ultimate objective being to provide activity‐related data that might be useful in farm rearing. Ten traits related to locomotion behaviour of 47 juvenile abalone were recorded under laboratory conditions. The results showed that the exploratory level varied between individuals. More exploratory individuals foraged more frequently, spent more time outside hides, started foraging earlier and preferred higher water flow rate than less exploratory individuals. More exploratory and less exploratory individuals also differed in their extensive movements, hide‐shift frequency and aggregation size. 相似文献