红头丽体鱼红魔丽体鱼杂交子一代胚胎发育及仔鱼形态学观察

对红头丽体鱼[Cichlasoma synspilum（♀）]红魔丽体鱼[C.citrinellum（♂）]杂交子一代（F1）（俗称血鹦鹉）的胚胎及仔鱼形态发育进行观察,描述了各发育时期的发育时序和形态特征。平均受精率为（91.333.06）%,平均孵化率为（91.672.08）%;血鹦鹉的受精卵呈椭圆球形,黏性,有浅黄、白灰和红褐3种颜色,无油球,平均卵长径为（1.890.04）mm;发育过程可分为6个阶段：受精卵阶段、卵裂阶段、原肠期、神经胚期、器官形成期和孵出期,并进一步分为28个发育分期;在水温（300.5）℃下历时约52 h 36 min完成孵化。初孵仔鱼全长（3.710.05）mm,卵黄长径为（1.740.09）mm,短径为（1.250.07）mm,于第3天开始摄食轮虫,孵出后第5天卵黄囊完全消失。第13 天全长（11.861.02）mm,各鳍条基本形成,进入稚鱼期。     

红头丽体鱼×红魔丽体鱼杂交子一代胚胎发育及仔鱼形态学观察

对红头丽体鱼[Cichlasoma synspilum（♀）]×红魔丽体鱼[C. citrinellum（♂）]杂交子一代（F1）（俗称“血鹦鹉”）的胚胎及仔鱼形态发育进行观察,描述了各发育时期的发育时序和形态特征。平均受精率为（91.33±3.06）％,平均孵化率为（91.67±2.08）％;血鹦鹉的受精卵呈椭圆球形,黏性,有浅黄、白灰和红褐3种颜色,无油球,平均卵长径为（1.89±0.04）mm;发育过程可分为6个阶段：受精卵阶段、卵裂阶段、原肠期、神经胚期、器官形成期和孵出期,并进一步分为28个发育分期;在水温（30±0.5）℃下历时约52 h 36 min 完成孵化。初孵仔鱼全长（3.71±0.05）mm,卵黄长径为（1.74±0.09）mm,短径为（1.25±0.07）mm,于第3天开始摄食轮虫,孵出后第5天卵黄囊完全消失。第13天全长（11.86±1.02）mm,各鳍条基本形成,进入稚鱼期。     

Activities of digestive enzymes during embryonic development in the crayfish Procambarus clarkii (Decapoda)

The red swamp crayfish, Procambarus clarkii (Girard), has become an important freshwater species for Chinese inland aquaculture because of its high commercial value and consumer demand. The aim of this study was to gather information about the activity of digestive enzymes at different embryonic stages of P. clarkii in order to increase our knowledge about digestive physiology and to guide technology for maternal culture so as to improve the hatching rate. Embryonic developmental stages were divided into six stages: I, fertilized egg; II, cleavage and blastula; III, gastrula; IV, egg nauplius; V, eye pigment forming; and VI, prepared for hatching. Pepsin-specific activity decreased significantly from stage I to stage IV. Although it increased at stage V, the activity level declined again before hatching. Both trypsin- and amylase-specific activity levels dramatically increased in the middle stages of embryogenesis, whereas at the other embryonic stages the activities of these two digestive enzymes were much lower. Lipase-specific activity exhibited a low level during all embryonic stages. The pattern of digestive enzyme activity was related to organogenesis and the utilization of yolk proteins at different embryonic stages.     

Predicting haddock embryo viability based on early cleavage patterns

Haddock, Melanogrammus aeglefinus, is a serial spawning, marine gadid characterized by low survivorship during the early life history stages. The potential for predicting future survival to hatching based on cleavage patterns of early embryos (8–32 blastomere stages) was investigated in order to improve efficiency of early rearing practices. In 2001, data from 36 egg batches (>95% fertilization) suggested that hatching success was inversely related to the percentage of embryos with abnormal cleavage. Mean percentage of normal cleavage did not differ throughout the spawning season but variability was much higher for embryos from early and late batches than those collected during the middle of the spawning season. In 2002, abnormalities in blastomere cleavage for 12 egg batches were further categorized as (1) asymmetric blastomere arrangement, (2) inequality of blastomere size, (3) poor adhesion between blastomeres and (4) poor definition of blastomere margins. Results suggested that all four abnormalities were co-occurring, which prevented negative effects on hatching success from being attributed to a single abnormality. Incubation of embryos with only one type of cleavage abnormality suggested that low adhesion between blastomeres significantly reduced embryo viability, while asymmetry in blastomere arrangement did not. However, because cleavage abnormalities tended to co-occur, hierarchical multiple regression revealed that asymmetry could be used to accurately predict hatching success, even if reduction in embryo viability was due to abnormalities other than asymmetry. Analysis of additional cleavage abnormalities suggested that complete separation between blastomeres was indicative of a very poor egg batch and resulted in little or no hatching, while cellular outcrops had no negative effect on hatching success. Information from detailed studies such as these could be used to predict hatching success of individual egg batches, allowing time and resources to be allocated more efficiently in hatcheries.     

Breeding and larval rearing of the camouflage grouper Epinephelus polyphekadion (Bleeker) in the hypersaline waters of the Red Sea coast of Saudi Arabia

This is the first report on the successful year-round natural spawning and larval rearing of Epinephelus polyphekadion (Bleeker) in captivity and under hypersaline water conditions of 42-43%₀ salinity in the Red Sea coast of Saudi Arabia. Although the fish spawned naturally once or twice a year during 1992-94 culture period, incorporation of cod-liver oil in the broodstock diet during the 1995 culture period enabled the fish to spawn continuously for 2-3 days in each month during March, April, May and August. The egg fertilization and hatching rates also increased during the 1995 spawning period. The egg fertilization rate varied from 90 to 100% with a mean of 96.5 ± 3.38%. The egg hatching rate varied from 70 to 95% with a mean of 83.1 ± 10.12%. The fertilized egg diameter averaged 757.3 ± 37.36 μm. There was a linear relation between the fertilized egg size and the egg hatching rate. The increase in the hatching rate relevant to the egg size was statistically significant (P < 0.01). The egg development time until hatching lasted for 19 h at 29°C. The newly hatched larval size ranged from 1.55-1.71 mm with a mean of 1.65 ± 0.052 mm in total length. The larval growth was slow in the early stages and the growth curve until metamorphosis showed a curvilinear pattern. Wide variations in larval size, range 22-47 mm with a mean of 33.40 ± 7.01 mm, were observed during the metamorphosis stage at day 50. No significant difference (P > 0.05) in growth and survival was observed between the larvae reared using white and grey coloured tanks. The larval survival up to metamorphosis was 1.6-4.7% with a mean of 2.98 ± 1.56% in the grey coloured tanks and 1.6-1.9% with a mean of 1.73 ± 0.16% in the white tanks. The results demonstrated the possibility of breeding E. polyphekadion under captive culture conditions. However, methods to improve the larval survival have to be pursued further for commercial farming of this species.     

The first spontaneous spawning of European hake Merluccius merluccius L.: characteristics of eggs and early larval stages

For the first time, a spontaneous spawning of hake was recorded in Spain in April 2009. The spawn was obtained from broodstock kept in captivity for two years at the facilities of the Spanish Institute of Oceanography in Vigo (NW Spain). Eggs were transparent, spherical and had an average diameter of 1.067 ± 0.024 mm; yolk occupied the majority of egg volume. The oil droplet had a diameter of 0.27 ± 0.03 mm. The incubation period of the eggs lasted for 4 days at 14°C and the duration from hatching to the total absorption of the yolk sac was between 5–7 days after hatching, at the same temperature. Newly hatched larvae had an average total length of 3.20 ± 0.13 mm and began feeding 6 days after hatching; a daily growth rate of 0.158 mm day‐1 was observed from hatching to yolk sac consumption. This paper describes the daily evolution of biometric and morphological characteristics of the different stages of embryos and larvae of European hake up to the age of 19 days.     

银白鱼人工繁殖受精卵附着介质筛选

为探索有利于银白鱼人工繁殖中的附着介质,提高孵化效率,选取4种受精卵附着介质(纱窗网、棕片、砾石、瓦片),开展了银白鱼人工繁殖试验,对不同产卵介质条件下银白鱼受精卵的孵化率、孵化时长进行了分析比较.结果表明,银白鱼人工繁殖受精率约为90％,采用4种介质的孵化率由高到低依次为:棕片(80％)、纱窗网(70％)、砾石(45...     

The effect of temperature and duration of incubation on the hatching of diapause eggs of Centropages hamatus (Lilljeborg) (Copepoda, Calanoida)

Diapause eggs of Centropages hamatus were used to investigate the effect of temperature and duration of incubation on egg hatching. Eggs were incubated for 10, 12, 14, 16, 20, 24, 28, 32, 36 and 40 h at 15°C and 14L–10D. After incubation for the designated period, eggs were transferred to 25°C and monitored periodically to determine egg hatching. Control eggs were incubated solely at 15°C and monitored for egg hatching. The greatest daily hatching success of eggs occurred within 1 or 2 days after transfer from 15°C to 25°C, while the controls required 3–4 days. The cumulative hatching success of eggs was significantly lower than the control, with the exception of eggs held for at least 36 h at 15°C before transfer to 25°C. These results indicate that overall time to hatching of diapause eggs of C. hamatus can be reduced by transferring the eggs to a higher temperature, for example, 25°C, following a minimum period of time (36 h) at reduced temperature, for example, 15°C. Exposure to 15°C for only 10 h does not appear to be sufficient to result in any subsequent hatching at higher temperature.     

雅砻江鲈鲤的人工繁殖、胚胎及卵黄囊仔鱼发育

采用不同配伍的外源激素对培育成熟的野生鲈鲤进行人工催产,并对其胚胎和1-10日龄卵黄囊仔鱼的发育进程进行详细的观察和描述。注射促黄体素释放激素类似物A2、地欧酮和绒毛膜促性腺激素的鲈鲤亲鱼组的催产效果明显好于注射鲤鱼脑垂体和促黄体素释放激素类似物A2的亲鱼组,效应时间为58h,平均受精率和平均孵化率分别为87.33%和90.75%。在水温(16±2)℃条件下,鲈鲤胚胎发育历时117.83h,所需积温为1855.33℃·h,出膜10d后仔鱼开始平游。鲈鲤胚胎发育分为受精卵、卵裂期、囊胚期、原肠胚期、神经胚期、器官形成期和出膜期7个阶段,共26个时期。分析发现,在人工催产配伍激素中添加适量的绒毛膜促性腺激素,有助于鲈鲤亲本顺利排卵;鲈鲤卵黄囊仔鱼在孵化出膜后的前5d处于内营养阶段,第6d起转入混合营养阶段,为仔鱼培育的第一危险时期。     

Bacterial destruction of the egg shell of common wolffish during incubation

Mortality of artificially fertilized, laboratory incubated eggs of common wolffish,Anarhichas lupus L., was 100% within 2–3 weeks, at the gastrulation step. The eggs from batches with a high proportion of normally cleavaged eggs died later than the eggs from batches with a low proportion of such eggs. Light micrographs of egg shells showed ulceration of the outer layer and subsequent destruction of the inner layer of zona radiata, caused byFlexibacter sp. The bacterial infection provoked premature hatching at later stages of embryonal development. Treating eggs with glutaraldehyde at a concentration of 600 mg l^–1 every third to fifth day during incubation prevented the mortality caused by bacteria.     

扁吻鱼胚胎发育及仔稚鱼形态与生长观察研究

文章采用干法受精获取受精卵的方法,对扁吻鱼(Aspiorhynchus laticeps)胚胎发育和仔稚鱼的形态变化进行观察.研究结果表明,扁吻鱼卵为沉性卵,卵细胞呈青灰色、微黏性.该次孵化共获取成熟卵21.45×104粒,受精率88.95％,孵化率93.27％.扁吻鱼成熟卵卵径(2.46±0.13)mm,受精卵吸水后...     

白鱚卵各胚胎发生阶段对高温突变、落下冲击和紫外线照射的感受性

本研究将白鱚卵的胚胎发生过程严格区分为27个阶段,并就各不同发生阶段的卵对高温突变、落下冲击和紫外线照射的感受性进行了详细的比较研究,得出了卵裂早期和原肠晚期至胚孔封闭期的卵对高温突变的感受性高;卵裂晚期至胚体出现期,对落下冲击的感受性高;对紫外线照射的感受性,则以胚体出现期为最高。文中同时分析了这种不同环境因素作用于相同鱼卵的同一发生阶段,产生不同影响的原因;建议在鱼类资源保护和鱼苗生产的孵化管理上,应尽量避免感受性较高的相应环境因素变化对鱼卵的影响。     

Egg quality in rainbow trout: The relation between egg viability,selected aspects of egg composition,and time of stripping

Batches of eggs (1 batch/female) from 17 rainbow trout in their first spawning season were stripped and reared separately, and the percentage which hatched and the percentage which reached the stage of first feeding were determined. The fertilised egg batches were analysed for egg wet weight, egg dry weight, chorion weight and levels in the eggs of free, bound and total lipid, precipitable protein, protein phosphorus, lipid phosphorus, calcium and iron. All determinations were made on single eggs, and six eggs from each batch were analysed for each variable. Results were expressed in absolute terms (as weight of component per egg) and as percentage of egg dry weight. Highly significant variations in all these aspects of egg composition were shown to occur between parent females. However, there was no significant correlation between the percentage of the original number of eggs which hatched and any one aspect of egg composition, except for a weak positive correlation (P<0.05) with the percentage of protein phosphorus in the eggs. Similarly, there was no significant correlation between the percentage of the original number of eggs which reached first feeding and any one aspect of egg composition except for weak positive correlations (P<0.05) with egg wet weight and with both the absolute level and the percentage of protein phosphorus in the egg. There was significant positive correlation (P<0.05) between the percentage of hatched eggs (alevins) surviving to first feeding and each of the following: egg wet weight, egg dry weight and absolute levels in the egg of bound lipid, precipitable protein and protein phosphorus. Egg batches with higher hatching percentage (>50%) differed significantly from those with zero hatching percentage in having (in absolute terms) higher egg weight, chorion weight, protein phosphorus (all P<0.001), egg dry weight, bound lipid and precipitable protein (all P<0.01) and (percentages) higher chorion weight (P<0.05) and protein phosphorus (P<0.001), and lower free and total lipid (both P<0.01) and iron (P<0.05). In a separate experiment to investigate the effects of allowing the eggs to be retained by the female within the abdominal cavity for increasing periods of time after ovulation, eggs were obtained from three females on three or four successive occasions 2–11 days apart. Although the above aspects of egg composition remained almost constant when the eggs were held in the female for up to 18 days after ovulation, the hatching percentage declined sharply within this period, in two females falling from over 90% to near zero. These results together indicate that the time of stripping of the eggs in relation to the date of ovulation is a much more significant determinant of egg quality than any of the chemical and physical aspects of egg composition which were investigated.     

The effects of heavy metals on embryonic development of fish (a review)

Early developmental stages of fish are particularly sensitive to water pollution. Heavy metals may affect various developmental processes during the embryonic period, which results in a reduction of offspring quantity and quality. Waterborne metals may accumulate in the gonads of spawners and adversely affect gamete production and viability, or exert direct toxic influence upon developing embryos. The egg shell does not fully protect the embryo against metal penetration, particularly during the swelling phase; thus, metals may accumulate in the egg. The results depend on metal concentration and range from developmental disturbances to death of the embryo. Metals disturb various processes of fish embryonic development and affect the development rate. Early stages just after fertilization are particularly sensitive to metal intoxication, when most disturbances and the highest embryonic mortality occur. Waterborne metals also promote developmental anomalies during organogenesis, including body malformations. Heavy metals often induce a delay in the hatching process, premature hatching, deformations and death of newly hatched larvae. All these disturbances result in reduced numbers and poor quality of the larvae, which show small body size, high frequency of malformations and reduced viability.     

Hydropower operations in groundwater‐influenced rivers: implications for Atlantic salmon,Salmo salar,early life stage development and survival

During their early life stages (egg maturation, hatching, alevin development), between late autumn and early spring, young Atlantic salmon are exposed to surface‐groundwater interactions in the hyporheic zone and may depend on influx of subsurface water during periods of regulated low discharge for survival. Two studies, one in a seasonally regulated river and one in a river exposed to hydropeaking, displayed unexpectedly high survival of eggs in surface de‐watered areas because of the influx of oxygen‐rich subsurface water. Field observations of newly hatched alevins in these two rivers showed them to be more sensitive (i.e. suffered higher mortality from) to surface de‐watering than were eggs. Exposure to dry conditions in drawdown areas was highlighted as the main cause for alevin mortality. Therefore, shorter periods of surface de‐watering in the river with hydropeaking resulted in higher alevin survival than the seasonally regulated river when still permanently drained after egg hatching. Greater consideration should be given to all early life‐history stages when implementing discharge release strategies, and the extent of groundwater influence and the potential for flexible hydropower operations should be taken into account.     

三疣梭子蟹常见病害及防治措施

为了探究三疣梭子蟹受精卵的离体孵化技术及效果,本研究先后开展了受精卵块最适分离液种类及作用条件的筛选、分离液处理不同发育期受精卵离体孵化的差异、分离液处理对受精卵卵膜的结构影响,及分离液处理受精卵对孵化后幼体活力的影响实验。结果显示,木瓜蛋白酶是一种较为理想的分离液,在浓度为0.09 g/mL,分离时间30 min时,分离率可达到99%以上;经过分离液处理后的各期受精卵均能孵化出幼体,卵内溞状幼体期离体胚胎孵化率最高,为89.0%±3.3%,未经处理的对照组为70.0%±4.8%;卵裂期离体胚胎孵化率最低,为58.0%±3.9%,对照组为31.0%±2.3%,与对照组相比,处理组的孵化率明显提高。透射电镜结果显示,经过分离液处理的受精卵卵膜结构疏松,且厚度降低,符合处理组孵化率增加这一现象,干露、福尔马林溶液胁迫和行为学测试对不同处理组的幼体进行质量评价的结果显示,处理组和对照组幼体活力无显著差异。研究表明,实验所获得的分离液可以有效提高三疣梭子蟹受精卵的分离率和孵化率,且不影响幼体质量,可为三疣梭子蟹及其他甲壳动物受精卵的离体孵化提供参考。本研究可为三疣梭子蟹的苗种繁育提供新的技术手段,也将为基因编辑辅助育种等技术的实施奠定基础。

     

Development of wolffish eggs at different temperature regimes

Embryonic development of common wolffish (Anarhichas lupus L.) was studied at constant temperatures 5.0, 7.0, 9.0, 11.0, 13.0 and 15.0°C. Duration of development from egg activation to several morphological stages including 50% hatching was determined. At 5.0–11.0°C, the survival rate of eggs to hatching ranged from 51 to 88% with a tendency to increase at 5.0 and 7.0°C. Morphological anomalies, bacterial contamination and large mortalities were observed in eggs incubated at 13.0 and 15.0°C. The period of hatching lasted from 10 to 50 d in different egg groups. Embryo length and yolk sac volume at identical morphological stages of development showed only slight relation to temperature. At lower temperatures newly hatched larvae were longer and at more advanced stages of ontogeny. Normal numbers of fin rays in larvae (mean values 74 for dorsal fin and 46 for anal fin) were observed at 5.0 and 7.0°C and in most larvae at 9.0°C. At 11.0 and 13.0°C, many rays were absent, with mean values for dorsal fin 60 and 39 respectively and for anal fin 28 and 4 respectively. The approximate upper limit for normal development of fin rays appeared to be 9.0 °C.     

半滑舌鳎胚胎发育及稚鱼变态过程观察

利用显微镜对半滑舌鳎胚胎发育及稚鱼变态过程进行连续观察,对各个时期的发育时间进行了记录,并对不同时期的特征用进行了拍摄。结果表明：半滑舌鳎成熟卵子呈球形,为多油球浮性卵。受精卵培养在水温21．6—22．8℃,pH值7．0～8．2。盐度30的海水中,历时39h仔鱼孵出。与其他硬骨鱼类基本相似,半滑舌鳎胚胎发育属于盘状卵裂,发育过程可分为：受精卵、卵裂期、囊胚期、原肠期、神经胚期、器官分化期、出膜期和初孵仔鱼。仔鱼孵化出膜进入胚后发育阶段,之后进入变态期,向成鱼转化。与牙鲆、大菱鲆等鲆鲽鱼类不同,半滑舌鳎稚鱼变态初期是在头顶两眼前上方形成一个横裂,右眼由此横列穿过,最终到达身体左侧,此后横裂逐渐愈合,变态完成,该过程历时3-4d,其形成机制有待进一步深入研究。     

Incubation experimentale et developpement embryonnaire de la daurade royale, Sparus aurata (L.), a differentes temperaturesIncubation and embryonic development of gilthead bream, Sparus aurata (L.), at a range of temperatures

Eggs of raised gilthead bream, Sparus aurata (L.), were incubated to hatching at various temperatures ranging from 7.7°C to 26.3°C. For four stages of development, the relationship between temperature and incubation time is given. Time from fertilization to hatching varies from 135 h at 11°C to 40 h at 21.3°C. In our experiments no egg hatched below 11°C or above 22°C. The highest hatching rate and the lowest rate of larval abnormalities were both observed at 14.5°C which is also the spawning temperature.     

三疣梭子蟹受精卵离体孵化技术

为了探究三疣梭子蟹受精卵的离体孵化技术及效果,本研究先后开展了受精卵块最适分离液种类及作用条件的筛选、分离液处理不同发育期受精卵离体孵化的差异、分离液处理对受精卵卵膜的结构影响,及分离液处理受精卵对孵化后幼体活力的影响实验。结果显示,木瓜蛋白酶是一种较为理想的分离液,在浓度为0.09 g/mL,分离时间30 min时,分离率可达到99%以上;经过分离液处理后的各期受精卵均能孵化出幼体,卵内溞状幼体期离体胚胎孵化率最高,为89.0%±3.3%,未经处理的对照组为70.0%±4.8%;卵裂期离体胚胎孵化率最低,为58.0%±3.9%,对照组为31.0%±2.3%,与对照组相比,处理组的孵化率明显提高。透射电镜结果显示,经过分离液处理的受精卵卵膜结构疏松,且厚度降低,符合处理组孵化率增加这一现象,干露、福尔马林溶液胁迫和行为学测试对不同处理组的幼体进行质量评价的结果显示,处理组和对照组幼体活力无显著差异。研究表明,实验所获得的分离液可以有效提高三疣梭子蟹受精卵的分离率和孵化率,且不影响幼体质量,可为三疣梭子蟹及其他甲壳动物受精卵的离体孵化提供参考。本研究可为三疣梭子蟹的苗种繁育提供新的技术手段,也将为基因编辑辅助育种等技术的实施奠定基础。