Laboratory observation on spawning,fecundity and larval development of amphioxus (Branchiostoma belcheri Tsingtaunese)     

Wu Xian-han  Zhang Shi-cui  Wang Yong-yuan  Zhang Bao-lu  Qu Yan-mei  Jiang Xin-ji 《中国海洋湖沼学报》1994,12(4):289-294

Although amphioxus is widespread in temperate and tropical seas, its population is diminishing because of environmental pollution. To keep the population of this evolutionarily important animal from diminishing, study on its reproduction and development is necessary. The main findings in this study on the spawning and fecundity of the amphioxus reared in laboratory and its larval development are as follows. 1. Water temperature markedly affected the spawning. It spawned only when water temperature reached 21°C. 2. Spawning of the amphioxus in laboratory was markedly extended. Initially, the amphioxus spawned at about 7:00 PM, but spawning time was postponed as spawning days went on. 3. The number of eggs produced by a female ranged from 1400 to 12800, average of 5800. This also represents the fecundity of the amphioxus because it shedded all eggs within the ovary at a time. 4. During the first few months of life of the amphioxus, its growth rate changed seasonally. The growth rate in summer and fall was greater than that in winter. 5. The pelagic larva became a benthic adult after 50 days. 6. The amphioxus reared in laboratory from fertilized eggs could produce fertile eggs and sperms. These findings can be a foundation for measures to address the problem of diminishing amphioxus population. Contribution No. 2274 from the Institute of Oceanology, Chinese Academy of Sciences This work was supported by CNNSF, and Chinese Academy of Sciences.  相似文献   

遮浪湾浮游幼虫主要类别的形态     

蔡国雄 《热带海洋学报》1992,(4)

在对粤东遮浪湾浮游幼虫样品进行初步鉴定和分类的基础上,对其中主要类别的45个典型幼虫作简要的形态描述。湾中浮游幼虫分属12个动物门,30种类型,其中环节动物多毛类幼虫分属10个科。个别类型和形态的浮游幼虫在我国海区属首次报道。  相似文献   

Salinity tolerance of northern Brazilian mangrove crab larvae, Ucides cordatus (Ocypodidae): Necessity for larval export?     

Karen Diele  Darlan J.B. Simith   《Estuarine, Coastal and Shelf Science》2006,68(3-4):600

The life cycle of the semiterrestrial mangrove crab Ucides cordatus includes pelagic larvae that are released into estuarine waters during the wet season and who may thus encounter potentially stressful low and variable salinity conditions. The effect of salinity on the survival of the zoea larvae, the number of zoeal stages and the duration of development from hatching to megalopa was experimentally studied by rearing larvae from the Caeté estuary, Northern Brazil, in seven salinity treatments (0, 5, 10, 15, 20, 25, and 30). For a better interpretation of the laboratory results, estuarine salinities were measured over five consecutive years during the species' reproductive season. The survival of the zoea larvae varied significantly with salinity, while the number of stages and the duration of their development remained constant. Development to megalopa took 20.77 ± 1.57 days and comprised five zoeal stages with ZI and ZII being euryhaline and later stages stenohaline. The newly hatched larvae stayed alive for up to 6 days in freshwater (average 4.32 ± 0.82 days), but did not moult to the second zoeal stage. ZII larvae first occurred from salinity 5 onwards and later zoeal stages at all tested salinities ≥10. However, the larvae only survived to megalopa at salinities ≥15, with highest numbers at salinity 30 (72%) and lowest at 15 (16%). Lethal salinities ≤10 occurred frequently in the estuary during the reproductive season. This suggests a need for larval export to offshore and thus more saline waters to allow for significant larval survival and maintenance of viable populations of this commercially important species. A regional rather than local approach for management is suggested due to the likelihood of long distance larval dispersal by offshore currents.  相似文献   

Genetic variation in restored Atlantic salmon (Salmo salar L.) populations in the Ulla and Lerez rivers, Galicia, Spain     

Saura  Maria; Caballero  Pablo; Caballero  Armando; Moran  Paloma 《ICES Journal of Marine Science》2006,63(7):1290-1296

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中国对虾人工育苗中直接投喂去壳卤虫卵的饵料效果   总被引：1，自引：0，他引：1  

蔡含筠  王寿芳 《海洋湖沼通报》1993,(2):66-71

为了有效地利用我国大量的低孵化率卤虫卵,我们自1989年—1992年,进行了去壳卤虫卵工厂化生产和在中国对虾育苗中直接投喂去壳卤虫卵的饵料效果的研究,应用结果表明:直接投喂去壳卤虫卵,对虾各期幼体均能正常变态进入仔虾期,其发育速度和密度与投喂卤虫无节幼虫的饵料效果基本相同。  相似文献   

Developmental duration and morphology of the sea star asterias amurensis, in tongyeong, Korea     

Sang-Gyu Paik  Heung-Sik Park  Soon Kil Yi  Sung Gyu Yun 《Ocean Science Journal》2005,40(3):65-70

The process of embryogenesis and larval development of the asteroid sea star Asterias amurensis (Lütken) was observed, with special attention paid to morphological change and larval duration. In reproductive season, mature sea stars were collected under floating net cages, located in Tongyeong, southern Korea. The mature eggs are 138 μm in average diameter, semi-translucent and orange in color, sperms in good condition appear light cream to white-gray in color. Embryos develop through the holoblastic equal cleavage stage and a wrinkled blastula stage that lasts about 9 hours after fertilization. Gastrulae bearing an expanded archenteron hatch from the fertilization envelope 22 hours after fertilization. At the end of gastrulation, rudiments of the left and right coelom are formed. By day 2, larvae possess complete alimentary canal and begin to feed. At this stage, the larva is called early bipinnaria. In 6day-old larvae, the pre- and post- oral ciliated bands form complete circuits and the bipinnarial processes start to develop. By day 12, the lateral and anterior projection of the larval wall processes along the ciliated bands begins to thicken and curl, and the ciliated bands become more prominent. By day 32, early brachiolaria are presented with three pairs of brachiolar arms. Advanced brachiolaria with a well-developed brachiolar complex (three pairs of brachia and central adhesive disc) occur 6 weeks after fertilization. In the field, spawning of the sea star was observed in April to May, settlement form larvae and just settlements seem to occur from June to July, and early juveniles occur from August to September. Although we had not described the end of brachiolaria stage, it can be tentatively estimated that the duration of the pelagic stage of A. amurensis is 40 to 50 days.  相似文献   

Larval distribution and growth of the rockfish, Sebastes capensis (Sebastidae, Pisces), in the fjords of southern Chile     

Landaeta  Mauricio F.; Castro  Leonardo R. 《ICES Journal of Marine Science》2006,63(4):714-724

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Influence of mesoscale oceanographic processes on larval distribution and stock structure in jackass morwong (Nemadactylus Macropterus: Cheilodactylidae)     

Bruce  B. D.; Evans  K.; Sutton  C. A.; Young  J. W.; Furlani  D. M. 《ICES Journal of Marine Science》2001,58(5):1072-1080

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滇池银鱼资源变动的生态学分析   总被引：2，自引：0，他引：2  

李砥 《海洋湖沼通报》2003,(2):69-73

以银鱼移植滇池后资源变动的状况为例分析了持续处于高密度状态下的r—选择型种群其密度对个体生长及生物量的影响、种群动态变化之间的关系，并对滇池银鱼衰退的主要原因进行了探讨。  相似文献   

皱纹盘鲍的分布水域与种苗放流效果   总被引：3，自引：0，他引：3  

李元山  冯月群 《海洋湖沼通报》1997,(4):48-54

本文通过皱纹盘鲍渔场的底栖生物资源的综合调查，在了解皱纹盘鲍分布水域的底质结构，大型海藻及敌害生物等资料的基础上，进行了不同区域的鲍种苗放流的比较试验，放流两年后，各区鲍种苗先后都达到商品规格，其试验结果，为增殖皱纹盘鲍，选择放流水域提供参考。  相似文献