绵羊粪便中毛圆线虫卵培养和感染性幼虫分离法的比较

目的　为比较毛圆线虫卵培养和感染性幼虫分离的几种方法。方法　采用培养中添加锯末,蛭石培养羊粪及分离幼虫用纱布袋浸泡、贝尔曼分虫法、广口罐分离法。结果　在绵羊粪便毛圆线虫卵的培养中,用锯末作为添加物较蛭石作添加物,幼虫的孵化率提高1.8倍,两者差异显著(P≤0.05);用纱布袋浸泡法进行粪便培养物中感染性幼虫的分离,较贝尔曼分虫法提高3.7倍;较广口罐分离法提高2.6倍。结论　以上方法分离的感染性幼虫再经蔗糖垫层离心提取后,可得到纯净、高密度的活性虫体。     

Larval development and salinity tolerance of Japanese flounder (Paralichthys olivaceus) from hatching to juvenile settlement

Salinity tolerance and growth of Japanese flounder Paralichthys olivaceus at different developmental stages were evaluated, including newly hatched larvae (nhl), yolk sac larvae (ysl), oil droplet larvae (odl), post oil droplet larvae (podl), premetamorphic larvae (preml) and prometamorphic larvae (proml), at 11 salinities from 5 to 55 g L^?1 for 96 h. The ontogenesis during the early life of P. olivaceus was investigated under hatchery salinity 35 g L^?1. The results showed that suitable salinities for nhl, ysl, odl, podl, preml and proml larvae were 10 to 25 g L^?1, 10 to 30 g L^?1, 20 to 30 g L^?1, 30 g L^?1, 10 to 30 g L^?1, 15 g L^?1, respectively, demonstrating an ontogenetic variation of salinity tolerance. The salinity tolerance of nhl, ysl, preml was higher than that of odl, podl and proml. The ysl and preml larvae displayed wide salinity tolerances. The present findings demonstrate that the suitable salinity for larviculture of P. olivaceus is 20–25 g L^?1 before the depletion of oil droplet; after that, higher salinity (30 g L^?1) should be ensured for the post‐oil droplet larvae; the premetamorphic larvae can be cultured at a wide salinity range (10–30 g L^?1), and the metamorphosed larvae should be reared at salinity about 15 g L^?1.     

短须裂腹鱼胚胎与仔鱼早期发育特性研究

为积累短须裂腹鱼的基础生物学资料,并对规模化人工繁殖提供理论指导,利用养殖条件下的短须裂腹鱼亲鱼,通过干法授精获得受精卵,对其胚胎发育和仔鱼早期发育全过程进行连续观察。短须裂腹鱼受精卵的平均卵径为2.36 mm,吸水膨胀后为3.68 mm,沉性卵、弱粘性、卵黄丰富。在水温(14±1)℃的条件下,受精后6 h 30 min进入卵裂期,20 h 55 min进入囊胚期,60 h 28 min进入原肠期,70 h 4 min进入原肠中期,77 h 52 min进入神经胚期,142 h肌肉开始收缩,177 h 46 min进入心动期,254 h 40 min开始出膜。孵化全过程所需积温为3 565.3℃·h。初孵仔鱼全长8.7 mm。出膜后第2~9天,胸鳍、鳃、口腔、眼色素、体内血管等器官相继发育完全;第10天仔鱼全长达15.15mm,鳔充气,鱼苗开始平游和觅食。孵化过程中应重点防控水霉病。早期仔鱼可以投喂轮虫、蛋黄或者豆浆等,待仔鱼捕食能力变强之后,可以投喂更加适口的枝角类、嫩口丰年虫等。     

A larval specific OBP able to bind the major female sex pheromone component in Spodoptera exigua(Hübner)

Odorant binding proteins(OBPs) in insects are postulated to solubilize and transport the hydrophobic odorants across the hydrophilic antennal lymph to the olfactory receptors(ORs) located on the dendrite membrane of the sensory neurons. OBPs in adult insects have been intensively reported, but those in larvae are rarely addressed. In our study, a full-length OBP c DNA, namely Sexi OBP13, was cloned by RT-PCR and RACE strategy from the heads of Spodoptera exigua larvae. The quantitative real-time PCR(q PCR) measurement indicated that Sexi OBP13 was highly expressed in larval head, but very low in other parts of larva and was not detected in any tissues of adult. The binding affinities of Sexi OBP13 to plant volatiles and female sex pheromone components were measured by competitive binding assays. Interestingly, Sexi OBP13 displayed a high binding affinity(Ki=3.82 μmol L–1) to Z9,E12–14:Ac, the major sex pheromone component of S. exigua, while low affinities to the tested host plant volatiles(Ki27 μmol L–1). The behavioral tests further confirmed that Z9,E12–14:Ac was indeed active to elicit the behavioral activity of the third instar larvae of S. exigua. Taken together, our results suggest that Sexi OBP13 may play a role in reception of female sex pheromone in S. exigua larvae. The ecological significance of the larvae preference to the adult female sex pheromone was discussed.     

不同饵料对泥鳅苗种前期培育效果的研究

本文研究了蛋黄、轮虫、豆浆、脱脂奶粉、鳗鱼饲料、鱼粉和酵母粉等7种饵料对泥鳅苗种前期培育生长和存活的影响。经过21 d培育,结果显示,泥鳅在不同饵料条件下的生长速度和存活率存在显著差异(P0.05),轮虫组生长速度较快,平均日增全长达到0.31 mm,最终存活率最高,达到39.5%;其次是蛋黄组,达到25.5%;其他组别最终成活率都较低。因此,在本试验条件下,轮虫作为泥鳅开口饵料效果最为理想。Bertalanffy、Gompertz和Logistic三种非线性生长模型均能很好地拟合泥鳅苗种生长曲线(R2=1.000),该期生长拐点在7~8日龄间。     

Larval fish distribution and retention in the Canary Current system during the weak upwelling season

The spatial distribution of fish larvae was studied in the Canaries‐African Coastal Transition Zone, outside the strong upwelling season. An onshore–offshore transition in the larval fish community structure was observed, from a coastal assemblage dominated by small pelagics (sardine, anchovy, mackerel), bounded by the upwelling front, to an offshore assemblage dominated by mesopelagic species (mainly Myctophidae, Phosichthydae, Gonostomatidae). Distribution of the neritic larvae was deeply influenced by the intense mesoscale activity found in the area, both horizontally (larvae were advected offshore but were always retained within the upwelling area) and vertically (larvae were deepened in the vicinity of two anticyclonic eddies). A combined effect of the upwelling front and a cyclonic–anticyclonic eddy dipole is likely the successful retention mechanism for these larvae. These results support the current belief that retention may be higher than previously thought in upwelling areas. Oceanic larvae were also collected in higher abundances near the front and an anticyclonic eddy. Neritic and oceanic larvae frequently showed a differentiated position in the water column, although they sometimes coexisted. Finally, larval connectivity between Islands within the Canary archipelago is suggested. The present study thus contributes to the understanding of the complex dispersal and retention processes in the Canaries‐African Coastal Transition Zone. However, results also highlight the poor knowledge of this region compared with the other three main Eastern Boundary Upwelling Systems in terms of ichthyoplankton dynamics. The importance of routine monitoring programs of commercial and non‐commercial species in the area is emphasized.     

Ammonia tolerance of Litopenaeus vannamei (Boone) larvae

The tolerance of Litopenaeus vannamei larvae to increasing concentrations of total ammonia nitrogen (TAN) using a short‐term static renewal method at 26°C, 34 g L^?1 salinity and pH 8.5 was assessed. The median lethal concentration (24 h LC₅₀) for TAN in zoea (1‐2‐3), mysis (1‐2‐3) and postlarvae 1 were, respectively, 4.2‐9.9‐16.0; 19.0‐17.3‐17.5 and 13.2 mg L^?1TAN (0.6‐1.5‐2.4; 2.8‐2.5‐2.6 and 1.9 mg L^?1 NH₃‐N). The LC₅₀ values obtained in this study suggest that zoeal and post‐larval stages are more sensitive to 24 h ammonia exposure than the mysis stage of L. vannamei larvae. On the basis of the ammonia toxicity level (24 h LC₅₀) at zoea 1, we recommend that this level does not exceed 0.42 mg L^?1 TAN – equivalent to 0.06 mg L^?1 NH₃‐N – to reduce ammonia toxicity during the rearing of L. vannamei larvae.     

The effect of density in larval rearing of the pullet carpet shell Venerupis corrugata (Gmelin, 1791) in a recirculating aquaculture system

The pullet carpet shell Venerupis corrugata is an economically valuable species in several European countries, however, nowadays stocks are under high fishing pressure. Hatchery production of juveniles for release is a major contributor to strengthen the stock and consequently improve the sustainability of the natural stocks. This study aimed to determine the feasibility of rearing V. corrugata larvae with different larval densities (10, 40 and 200 larvae per mL) in a recirculating aquaculture system (RAS), compared with the traditional larval rearing methodology (Batch). The mean survival, growth and metamorphic rate of V. corrugata larvae in RAS was higher (11.1%; 71.3 μm; 21.6% respectively) than in the Batch system, in all tested densities. The larval growth was not affected by the initial density until 40 larvae per mL, however, 200 larvae per mL decreased the larval growth in length nearly 54 μm. The larval rearing time was shortened in 2 days in the RAS system. The physical, chemical and microbiologic parameters suggested that the tested densities were not excessive to disturb the biofilter stability of RAS. The V. corrugata larval rearing performed at high larval stocking densities in RAS system present a reduction in the operating costs to produce this species.     

New species in aquaculture: are the striped venus clam Chamelea gallina (Linnaeus, 1758) and the surf clam Spisula solida (Linnaeus 1758) potential candidates for diversification in shellfish aquaculture?

The surf Spisula solida and the striped venus Chamelea gallina clams support important fisheries in Europe. These fisheries have been affected by inter‐annual fluctuations in stock abundance and recruitment failures. Aquaculture could contribute to address these problems through the production of larvae or juveniles for stock‐enhancement programmes. In the present study, the prerequisites to produce these species in hatchery were established. Of the different methods used to obtain gametes (thermal stimulation, scarification and flow through), C. gallina spawned in the flow through only. By its turn, the best method for obtaining gametes for S. solida was stripping. Higher survivals of D‐larvae were found at 15 and 17°C. The greatest larval survival and growth rates were obtained from larvae fed Isochrysis aff. galbana (T‐iso). First C. gallina and S. solida pediveliger larvae were found at day 8 and day 26 respectively. The presence of metamorphosed larvae found even in the unfed treatment for C. gallina and for S. solida is an advantage for aquaculture production. After metamorphosis, the S. solida juveniles' survival was quite low, whereas there was no mortality for C. gallina juveniles reared without substrate regardless the diet provided. Juveniles fed the binary diet (Chaetoceros calcitrans ‐ C. cal + T.iso) and the monodiet T‐iso showed relatively higher growth in shell length and weight than C. cal. The hatchery production of these two species was possible, however the results of this study showed that C. gallina can be more attractive for aquaculture than S. solida.