The effects of cadmium and copper on embryonic and larval development of ide Leuciscus idus L.

The effects of Cd and Cu on embryos and larvae of the ide Leuciscus idus were evaluated. The ide is an European cyprinid fish, natural populations of which tend to decrease. The ide is also used as a bioindicator organism to evaluate water quality. However, sensitivity of ide early developmental stages to heavy metal intoxication is not known. Fish were exposed to Cd or Cu (100 μg/L) during embryonic, larval or both developmental periods. Survival of the embryos, time of hatching, size and quality of newly hatched larvae were evaluated at the end of embryonic period. Correctly developed larvae from the control and Cd or Cu-exposed groups were transferred to clean water, Cd or Cu solutions (100 μg/L) immediately after hatching. Larval development was observed, and the larvae were photographed. Time of yolk sac resorption, onset of active feeding and swim bladder inflation were evaluated, and the measurements were done on body and swim bladder size. The results showed that exposure of embryos to Cd and Cu significantly reduced embryonic survival and increased frequency of body malformations and death in newly hatched larvae and delayed hatching. Exposure to Cd and Cu during larval period reduced larval survival, growth and delayed development (yolk utilization, beginning of active feeding and swim bladder inflation). Cadmium was more toxic to the ide embryos and larvae than copper. Exposures to metals during embryonic period alone caused adverse impact on larval performance even when larval development took place in clean water. However, exposure of embryos to Cu reduced toxic impact of metal on larvae in continuous Cu exposure compared to the non-preexposed fish, but no such an effect occurred in case of Cd exposure. The results show that even a short-term exposure to Cd or Cu during early development of ide may adversely affect recruitment of this species. Among the measured endpoints, quality of newly hatched larvae (frequency of body malformations and larvae dead immediately after hatching) and swim bladder size were the most sensitive to intoxication with both metals. Embryos were more sensitive to Cu intoxication than larvae, while in case of Cd, sensitivity of both stages was similar.     

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。     

Hatching time effect on the intra‐spawning larval morphology and growth in Northern pike (Esox luciusL.)

Based on the analysis of 11 morphometric variables of body (total length, body area and perimeter, myotome height and eye diameter) and yolk sac (length, height, area, perimeter and volume) of pike larvae, the aim of this study was to evaluate how larval size at hatching and growth of larvae hatched from single egg batches vary according to three hatching times: early, mid and late. Hatching time structures strongly pike larval morphometrics. Early hatched larvae have smaller body sizes at hatch, faster growth and higher yolk use efficiency than late hatched ones. Early hatched larvae seem to be premature and hatch at precocious developmental stage whereas late hatched individuals continue their growth within the egg shell and hatch at larger size but with lower reserves (yolk). A compensatory growth phase was observed for the early hatching pike larvae particularly during the first 5 days post hatch. Consequently, no significant difference in body parameters was recorded from day 10 post hatching whatever the hatching time. The higher growth accomplished by early hatched larvae may be related to a particular metabolic activity that converts more efficiently yolk into body tissues.     

温度对云纹石斑鱼(Epinephelus moara)(♀)×七带石斑鱼(Epinephelus septemfasciatus)(♂)杂交F1胚胎发育和仔鱼活力的影响

用控温仪设定温度组,观察了在不同温度条件下(13℃、15℃、17℃、19℃、21℃、23℃、25℃、27℃、29℃、31℃)云纹石斑鱼(E.moara)(♀)×七带石斑鱼(E.septemfasciatus)(♂)杂交F1的胚胎发育情况,并对实验12 h后的好卵率、12 h后的胚胎发育时期、受精卵的孵化率和初孵仔鱼的畸形率进行了记录;仔鱼孵化出膜后,对其进行了耐饥饿实验,测定其每天的存活率和生存活力指数(Survival activity index,SAI)。实验结果表明,受精卵胚胎发育周期与温度呈正相关的关系,其受精卵孵化的适宜温度范围是17–25℃,温度低于17℃时,孵化率随温度的降低而降低,畸形率反之;温度为13℃时,不能孵化出仔鱼;温度高于25℃时,孵化率随温度的升高而降低,畸形率反之;仔鱼的SAI值随着温度的变化先升高后降低,在温度为17–21℃时,SAI值较高,分别为32.14±2.83、32.30±1.29、22.98±1.42,其他温度条件下SAI值均低于这3组。     

The effects of constant and oscillating temperature on embryonic development and early larval morphology in longfin yellowtail (Seriola rivoliana Valenciennes)

Constant and oscillating egg incubation temperatures on embryonic development and early larval morphology were studied in longfin yellowtail (Seriola rivoliana Valenciennes). We investigated the effects of constant temperatures from 16 to 32°C on embryo development and larval morphology at hatch, and whether oscillating temperature during embryogenesis could lead to larval morphological variations. After hatching, larval morphology and development during yolk sac (YS) utilization were examined in larvae at constant temperatures and larvae at 25°C that had oscillating temperature during egg incubation. Hatching rates were > 75%, only decreasing to ~ 50% at 30°C. At constant temperatures, the largest larvae occurred at 22 and 24°C. The oscillating temperature did not affect the timing of embryo development but resulted in larger and smaller larvae with a smaller and bigger YS, respectively, with a similar hatching time. Therefore, a growth response occurred in embryos during a window of development before hatching, depending on the adaptive response to temperature (spawn‐specific). After hatching, most of the YS was absorbed within 24 hr in all treatments, and the growth of the larval head was a priority with an optimal development at 26°C. There was compensatory growth in smaller larvae resulting in similar sizes after YS utilization, but larvae showed variations in body structure that could be important in further aquaculture research.     

Is batch variability in hatching time related to size heterogeneity and cannibalism in pikeperch (Sander lucioperca)?

Larval size heterogeneity is known to induce cannibalism, and procedures to avoid larval size differences are consequently implemented already during egg incubation and hatching. We investigated the relation between larval development variability, size heterogeneity and cannibalism in pikeperch. Larvae were sorted into five groups according to the time of hatching during a 65‐h period. The larvae with different times of hatch were then reared separately or together during an 18‐day period. Late hatched larvae were longer (P=0.003) and had less yolk remaining (P<0.001) than early hatched individuals at the time of hatching. However, on 11 days post fertilization, the late‐hatching larvae tended to have larger yolk reserves than earlier hatched individuals (P=0.07). Furthermore, the next day, a lower proportion in the late fraction had switched to exogenous feeding (P=0.024). That larvae with a late hatching time developed slower suggests a positive relationship between the hatching time and the embryonic developmental rate. However, differences in the length and available yolk reserves at hatching between larval fractions with different hatching times suggest that hatching is not strictly associated with a specific developmental stage, and that factors other than the development rate of the embryo are involved in the timing of hatching.     

Comparative study of the effects of heavy metals on embryonic development of zebrafish

This study aimed to investigate the effects of heavy metals, such as copper, zinc, iron, cobalt, chromium, aluminium, manganese and molybdenum, on zebrafish egg hatching rate and the subsequent survival rate of the larvae. Each metal was used in the various concentrations of0.05 mg/L, 50 mg/L and 500 mg/L to detect the threshold limit of tolerance. The study's results showed significant differences in the hatching and survival rate of larvae between the control group and most of the experimental groups when adding heavy metals in various concentrations. The highest concentration (500 mg/L) of the induced heavy metals tested in this study resulted in total egg or larval mortality within 96 hr and significantly lower egg or larval life expectancy. Among the tested metals, zinc and molybdenum had the most significant impact on hatching time, in contrast to iron that did not differentiate the results from the control group. Copper, cobalt, chromium, aluminium and manganese did affect zebrafish eggs depending on their exposure concentrations, which differentiated the results from the control group. Also, the study's findings demonstrate a significant dependence of the hatched egg heart rate on the metal concentration, and in particular, higher concentrations of metals correspond to higher heart rate. Zinc, Molybdenum and copper was proved to be the most toxic heavy metals causing increased hazard rate to mortality up to 96 hr and shorter life expectancy. Finally, skeletal deformities that occasionally observed did not significantly affect the total life expectancy of the hatched eggs.     

Cu2+、Zn2 、Pb2 对七带石斑鱼(Epinephelus septemfasciatus)胚胎和初孵仔鱼的毒性效应

在(21.0±0.5)℃条件下,研究了Cu2+、Zn2+、Pb2+3种金属离子对七带石斑鱼胚胎和初孵仔鱼的毒性效应。结果表明:1)随着3种金属离子浓度的升高,受精卵的孵化速率和孵化率逐渐降低,畸形率逐渐增加。重金属引发胚胎发育发生各种畸形,如胚体增生异常而死亡、尾芽弯曲,仔鱼不能正常出膜而死亡,初孵仔鱼脊椎弯曲多呈L、S、V型或尾部未展开呈逗号状畸形。综合孵化速率、孵化率和畸形率等指标,可以看出,3种金属离子对胚胎发育的毒性大小依次为Cu2+Zn2+Pb2+;2)初孵仔鱼的毒性试验周期为96 h,随着时间加长,仔鱼的存活率逐渐降低,且金属离子浓度越大,其下降幅度越大。此外,仔鱼出现脊椎S、V型弯曲等畸形也越来越多。通过计算各时间段的半致死浓度(LC50)和安全浓度得出,3种金属离子对初孵仔鱼的毒性大小依次为Cu2+Pb2+Zn2+。本研究的一系列数据可以为新渔业水质标准的制定和水环境的监测提供理论参数,为七带石斑鱼等鱼类繁育养殖中的重金属监测与治理提供重要科学依据。     

Effects of Photoperiod on Embryos and Larvae of Tawny Puffer,Takifugu flavidus

To determine the optimal condition of photoperiod for embryo development and larval culture of tawny puffer, Takifugu flavidus, the effects of photoperiod on egg hatching and the growth and survival of larvae from 3 to 23 d after hatching (dah) were assessed. The results show that photoperiodic responses varied with the developmental stage during the early development of tawny puffer. Photoperiod did not significantly affect the hatch rate, viability of 24 h post‐hatch larvae, and total mortality rate of tawny puffer embryos; however, it affected the incubation period, which significantly increased with increasing photoperiod from 6 to 24 h. The shortest incubation period was predicted to occur at 3.56 h day length from the quadratic relationship. However, photoperiod strongly affected the growth and survival of the tawny puffer larvae from 3 to 23 dah. Increasing the day length resulted in improvement of the larval growth and survival within the 0–12 h day length range; however, beyond the 12 h day length, a longer day length was not beneficial, and a 24 h continuous light had a negative effect on growth. From the quadratic relationships, the highest growth and survival rates were predicted to occur at 14.16 h and 17.74 h day length, respectively. Therefore, the optimal photoperiods for tawny puffer embryos and larvae were 3–6 and 12–18 h day length, respectively. The results of this study are useful in increasing the production of the species during incubation and larval culture.     

Effects of different step‐wise temperature increment regimes during egg incubation of Atlantic cod (Gadus morhua L.) on egg viability and newly hatched larval quality

We carried out an experiment to determine how rapidly the early incubation temperature of Atlantic cod eggs can be increased without affecting normal embryonic development and hatching. Atlantic cod eggs were incubated at a constant low temperature (4.5 ± 0.5°C; T5 – control) and four temperature increment treatments where the temperatures were increased stepwise from 4.5°C at zygote stage to 9.5 ± 05°C (T1‐8 h, T2‐32 h, T3‐64 h and T4‐96 h). Embryonic cell symmetry, embryonic mortality, hatching success and larval skeletal abnormalities, length and yolk sac volume were recorded. Larval samples were also taken at hatch for histological analysis. Except for higher egg mortality and lower hatching success in the T1, the differences among experimental groups were minor. Cell asymmetries and embryo mortalities were not significantly different between the control and T2–T4 treatment groups. Control larvae were significantly longer and had smaller yolk reserves at hatch than T1–T4 larvae and larvae from T2 had the largest yolk reserves. Tissue and organ histology of hatched larvae were similar. Considering embryonic cleavage pattern, hatching success and larval morphology and histology, a gradual increment of temperature in 32 h seems to be the better choice for future developmental programming studies in Atlantic cod.     

罗氏沼虾胚胎附着机制的初步研究

甲壳动物十足目的大多数种类,其受精卵自产出后就附着于亲体腹部,并完成胚胎发育过程直至孵化,这对于胚胎的发育、保护和幼体散布有重要的生物学意义。胚胎的附着机制较为复杂,与刚毛、卵柄、卵索、卵膜和黏液腺有关:卵柄和卵索的形成决定了胚胎发育的顺利进行;卵膜的变化影响着胚胎的附着;黏液腺在胚胎附着过程中形成卵柄和外层卵膜,胚胎是依靠卵柄或卵索附着于腹肢的刚毛上,进而完成胚胎发育过程。本研究采用常规组织学和扫描电镜的方法研究了罗氏沼虾(Macrobrachium rosenbergii)胚胎及其附着结构。结果表明,胚胎附着与母体腹肢的结构、黏液腺分泌的黏液相关,也与胚胎表面结构、次级卵膜的形态和结构密切相关。原肢底节和内肢刚毛密而长,基部有细小的分支,有利于胚胎的附着,外肢刚毛羽状则有利于胚胎的托附和保护。抱卵雌虾腹肢的原肢和内肢上布满腹肢黏液腺分泌的黏液;携卵刚毛中空、壁厚,刚毛外壁由微绒毛状结构组成,扩大了携卵刚毛的表面积,以利胚胎附着。胚胎外表面由初级卵膜和次级卵膜组成,次级卵膜主要由卵巢黏液腺分泌的黏液参与形成。排卵时,受精卵依靠坚韧的次级卵膜相互粘连,同时,部分受精卵在刚毛上滑动、旋转,并借助次级卵膜逐渐形成了卵柄或卵索固着在腹肢刚毛上。从受精卵到胚胎孵化,胚胎之间最主要的连接方式是依靠次级卵膜的连接。胚胎的表面有许多褶皱和黏液,利于胚胎的附着以及胚胎对溶氧和小分子物质等的通透。以上结构与附着相适应,保证了胚胎发育的顺利进行和幼体的正常孵化。本研究旨为进一步认识甲壳动物胚胎附着机制、胚胎发育和人工育苗的研究提供参考。[中国水产科学,2007,14(1):67-73]     

云纹石斑鱼胚胎发育及仔、稚、幼鱼形态观察

对云纹石斑鱼Epinephelus moara胚胎发育及仔、稚、幼鱼形态进行了观察与研究,详细描述了各发育期的形态特征和发育时间。结果表明:1)在水温22±0.2℃、盐度30、溶氧7.8mg/L、pH8.25的条件下,云纹石斑鱼的受精卵历时38h 17min开始孵化出膜。胚胎发育可分为受精卵、卵裂、原肠、神经胚和器官形成及出膜6个阶段,受精、胚盘形成、2细胞等28个时期。2)在水温23±1℃,盐度30±3,DO≥5mg/L,pH8.0±0.5的海水中,培育至5d,卵黄囊完全消失,成为后期仔鱼;培育至27d,发育最快的云纹石斑鱼结束仔鱼期,进入稚鱼期;培育至65d,发育最快的稚鱼完成变态,成为幼鱼。胚后发育过程主要是根据卵黄囊、鳍膜、鳞片、体色及第1腹鳍棘与第2背鳍棘相对长度的变化分为仔鱼、稚鱼和幼鱼3个时期。其中仔鱼期又根据其卵黄囊的有无划分为前期仔鱼和后期仔鱼。     

Egg Quality in Wild and Broodstock Cod Gadus morhua L.

Problems concerning egg viability or egg quality have received increasing attention, in relation to cultivation as well as to the assessment of reproduction of wild fishes. One important aspect of this paper is to discuss the use of cell morphological characteristics as indicators of egg quality in cod. Early cellular malformation rates in egg batches show a positive correlation with their later egg and larval survival, and can be used as a rough prediction of normal development and mortality rates.
The natural mortality rate offish eggs is not well understood, and observed egg viability of captive cod is are discussed in relation to egg viability in the wild. Results from recent work indicated that approximately 10% of naturally spawned cod eggs from both wild fish (planktonic samples) and from a broodstock had abnormal cleavages at the 2–128 cell stage. Eggs with observed early abnormal cell-cleavage showed very poor survival and hatching rates. For broodstock cod, egg viability was highest during the peak of the spawning season.
The North Atlantic cod may provide a good model species for studies of egg viability variations in wild and captive individuals, as its reproductive biology is well studied. It is now documented that the egg production in cod is dependent on fish age, nutritional status, batch number, and stress factors.     

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...     

温度、盐度对条石鲷胚胎发育影响及初孵仔鱼饥饿耐受力

研究了盐度、温度对条石鲷胚胎发育的影响和初孵仔鱼对饥饿的耐受力。结果表明,胚胎发育的适宜盐度范围为20～35,最适盐度范围为25～30,孵化率都在89%以上,盐度低于20或高于35,孵化率都降低。盐度对孵化时间有一定影响,盐度高于35或者低于15条件下孵化时间都延长。胚胎发育的适宜温度范围为21～27℃,孵化率都在77%以上,最适温度范围为23～25℃,孵化率达89%以上,低于19℃或者高于27℃时孵化率降低且初孵仔鱼畸形率升高。胚胎孵化时间与温度成负相关关系,胚胎发育速率与温度成正相关关系。条石鲷胚胎发育的生物学零度（阈温度）为10.06℃,有效积温值为405.3℃·h。对胚胎发育的Q10值进行了计算。饥饿条件下,条石鲷初孵仔鱼8日龄全部死亡,半数死亡时间出现在第6天,饥饿对初孵仔鱼生长具有明显的抑制作用。     

重金属对鱼类早期发育的生态毒理效应

鱼类早期生活阶段对外界环境极为敏感,即使低浓度的污染物暴露也可能对其胚胎发育、仔鱼生长存活造成损害,导致种群数量和质量的降低。研究污染物对鱼类早期生活阶段的毒理效应和机制是揭示污染物对生物种群和水生生态系统潜在风险的有效途径。重金属对鱼类的影响在精、卵发生时即可显现。例如,抑制卵(精)母细胞成熟和精子活力降低,使受精率降低;影响受精卵吸水膨胀过程,改变胚胎发育速率、引起胚胎畸形、影响胚胎心率、改变孵化时间、降低孵化率;影响初孵仔鱼体长、造成仔鱼畸形、影响卵黄囊吸收和胚后仔鱼发育生长、摄食行为等。重金属对鱼类早期发育阶段的毒性效应主要取决于金属种类、暴露浓度和受试鱼种及其发育阶段。此外,外界环境条件等因素也会对重金属的毒性产生显著影响。本研究综合分析国内外关于重金属污染物对鱼类精卵、胚胎、仔鱼等早期发育过程生态毒理效应的研究进展,并结合相关报道阐述了其毒性机制。     

Morphological and biochemical characteristics of phyllosoma after photothermal manipulation of reproduction in broodstock of the spiny lobster, Jasus edwardsii

The consequences of photothermal manipulation of reproduction in Jasus edwardsii broodstock on the morphology of newly hatched larvae and their biochemical characteristics were examined. The treatment of compressed temperature and photoperiod delayed the time of moult, mating and egg extrusion, but reduced the period until larval hatch, and reduced the hatching duration in individual females compared to the ambient treatment of simulated natural photoperiod and water temperature. Thus, the availability of phyllosoma for hatchery rearing was extended. However, the broodstock in the compressed treatment produced smaller phyllosoma and more larvae failed to develop beyond the naupliosoma stage than animals from the ambient cycle. Phyllosoma from the compressed treatment contained a higher proportion of polar and triacylglycerol lipid classes, lower wax esters, elevated levels of the essential fatty acid docosahexaenoic acid, a higher ratio of n-3/n-6 fatty acids, and lower levels of ascorbic acid. The changes in larvae from the compressed treatment may adversely affect their viability, and are probably due to the higher water temperatures experienced during late embryonic development.     

重金属对鱼类的生态毒理学研究进展

水体重金属污染是目前日益严重的环境问题之一,随着工农业的发展,生产生活中的重金属可以通过多种途径进入水生态系统。水生态系统重金属污染具有来源广泛、易在生物体内蓄积、不易分解的特点,不仅对水生生物各类群及整个生态系统产生影响,还可以通过食物链间接危害人类健康,重金属对水生态系统的影响及其对水生生物毒理学研究已成为全球环境研究的热点。鱼类作为水生态系统重要的组成部分,近年来国内外针对重金属及其生态毒理学开展了大量的研究工作。在总结分析国内外研究的基础上,综述了鱼类重金属的来源、赋存和迁移转化规律,阐述了重金属对鱼类个体水平、细胞水平、分子和遗传水平的毒理学效应以及鱼类对重金属的耐受机制;并结合重金属对鱼类生态毒理学研究中不足,对未来可能的研究方向进行了展望。     

棕点石斑鱼(♀)×鞍带石斑鱼(♂)杂交子代胚胎及仔稚幼鱼发育的跟踪观察

本研究阐述了棕点石斑鱼(♀)×鞍带石斑鱼(♂)杂交子代(简称珍珠龙胆石斑鱼)的胚胎发育和仔稚幼鱼形态发育的特征及其养殖过程中的一些难点、要点,以期为今后苗种的规模化培育生产提供参考依据。通过对珍珠龙胆石斑鱼各个发育期连续取样,系统观察并记录各发育期的形态变化及生长特征。结果表明,1)在水温27-28℃条件下,历时25 h 25 min孵化出膜,整个发育过程划分为卵裂期、囊胚期、原肠胚期、神经胚期和器官形成期。2)在水温(27.0±0.5)℃、盐度30、p H 8的培育条件下,根据卵黄囊、第二背鳍棘和腹鳍棘的生长与伸缩及鳞片、体色的变化将胚后发育分为仔鱼、稚鱼、幼鱼3个时期。仔鱼期根据卵黄囊的有无分为前期仔鱼和后期仔鱼。初孵至孵化后4 d为前期仔鱼;孵化后5 d,仔鱼卵黄囊完全消失,成为后期仔鱼;孵化后32 d,50%的仔鱼进入稚鱼期;孵化后46 d,50%的稚鱼完成变态,成为幼鱼。初孵仔鱼的全长平均为(1.65±0.11)mm,发育至70 d时,幼鱼平均全长已达(75.47±0.19)mm。跟踪观察的结果发现,珍珠龙胆石斑鱼作为杂交子代,从受精到发育的各阶段均能健康正常地生长发育,且生长快速、抗病力强,具有"虎斑头、龙胆尾"的外型,具有明显的杂交优势。     

Egg quality and egg pigment content in salmonid fishes

The widespread belief in the superior quality of highly pigmented eggs is examined by bringing together evidence concerning the effect of the carotenoid content of salmonid eggs on their viability. It is concluded that, in rainbow trout, there is not a simple linear relation between these two quantities. There is some evidence that a critical level exists (ca. 1–3 μg carotenoid/g eggs) above which hatching percentages of more than 80% may be expected but below which hatching percentages of less than 50% tend to occur. However, the evidence is not conclusive and suitable experiments under controlled conditions have not been performed. Eggs of wild fish are frequently of higher quality than eggs of farmed fish but this difference is not necessarily caused by the large difference in egg carotenoid content but rather by the generally superior nutrition of the wild fish. The effects of egg carotenoid composition, including the artificial pigmentation of eggs with dietary canthaxanthin, on egg viability are considered, and the possible functions of egg carotenoids during embryonic development are discussed. Only one such function has been conclusively demonstrated, namely that they act as a source of pigment for the chromatophores of the alevin. Analogy with other animals suggests that β-carotene, when present, may act as a precursor of vitamin A. There is growing evidence that carotenoids may perform some undefined function in respiration of egg or alevin when oxygen is deficient.