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1.
在室内养殖条件下,研究厚颌鲂仔鱼的摄食、耐饥饿和恢复生长能力.试验结果表明:(1)仔鱼在孵出后2~3 d开口摄食,卵黄囊在之后的2 d耗尽,饥饿仔鱼在12~13日龄达到不可逆点(PNR);(2)饥饿仔鱼的初次摄食率在卵黄囊耗尽时达到最高,保持在80%以上的时间为7 d;(3)仔鱼在PNR后死亡率急剧增加,PNR后第3 d仔鱼全部死亡;(4)经恢复生长试验,延迟3 d投饵对仔鱼的存活率影响不大,延迟3~6 d投饵对仔鱼全长生长影响不大.  相似文献   

2.
饥饿对唐鱼仔鱼摄食和生长的影响   总被引:5,自引:3,他引:5  
用初次摄食率测定法测定饥饿胁迫下唐鱼(Tanichthys albonubes)仔鱼耐饥饿能力,观察了饥饿对仔鱼摄食、生长和形态发育的影响。结果表明,水温24.0~28.5℃条件下仔鱼在孵化后第2.5~3d开口摄食,初次摄食率为33.3%,最高初次摄食率为100%并持续4d;混合营养期约2d;第5d卵黄耗尽,并达到最高摄食强度;第8.5d进入不可逆点(PNR),PNR有效积温为222.7d.℃,第10d死亡率超过50%,12d全部死亡。饥饿对仔鱼发育起延迟作用,混合营养期延迟投喂,仔鱼生长发育水平明显低于正常投喂仔鱼,饥饿仔鱼发育停滞且在PNR前后负增长并出现胸角。本文讨论了仔鱼耐饥饿能力与生境、生活史策略的关系。  相似文献   

3.
稀有鮈鲫仔鱼的摄食和耐饥饿能力   总被引:10,自引:2,他引:8  
研究了室养条件下稀有的鮈鲫的摄食和耐饥饿能力。结果表明,仔鱼一般在孵出后1.5d-2d开口摄食,此时卵黄囊容量约从初孵时的0.1降至0.03mm~3以下,在其后1-1.5d卵黄物质消耗殆尽;饥饿仔鱼的初次摄食率变化型式为:开始较低,然后迅速升高,约在卵黄吸尽时达到最高,最高初次摄食率为100%,保持在80%以上的时间为5d;持续饥饿或延迟开始摄食时间对仔鱼的生长、发育、存活有深刻的影响,饥饿仔鱼全长负生长及饥饿体征明显;初孵仔鱼持续饥饿8-10d达不可逆点(PNR),饥饿仔鱼在PNR前1.5d时存活率低于50%,在PNR后2d全部死亡。  相似文献   

4.
以人工繁育的俄罗斯鲟仔鱼为对象,采用实验生态学方法,研究了初次摄食时间对生长及存活的影响。结果表明:在水温17.4 ℃下,仔鱼在9~10日龄初次摄食,初次摄食前投喂对俄罗斯鲟仔鱼的生长和存活无显著性影响,延迟2 d以上初次摄食对生长影响明显,存活率在18日龄初次摄食时显著下降,24日龄时饥饿仔鱼全部死亡;23~24日龄时仔鱼如不能建立外源营养即达到饥饿不可逆点(PNR)。人工养殖条件下,俄罗斯鲟仔鱼必须在初次摄食后14 d内建立起主动摄食能力才能保证其仔鱼的正常发育、生长和存活。  相似文献   

5.
太平洋鳕仔鱼饥饿实验及不可逆生长点的确定   总被引:2,自引:0,他引:2  
李艳秋  姜志强  孙阳  毛明光  孟祥科 《生态学报》2014,34(14):3873-3878
通过研究饥饿胁迫对太平洋鳕仔鱼生长、形态和行为的影响,确定太平洋鳕仔鱼最佳投饵时间及不可逆点,以期为太平洋鳕人工育苗提供科学参考。实验设饥饿组和摄食组进行研究。结果表明,在水温10.0—11.0℃时,太平洋鳕仔鱼在孵化后第5天开始摄食,此时卵黄囊容量约从初孵时的0.2402mm3降至0.0062mm3,卵黄囊体积随仔鱼生长逐渐变小。从第8日龄开始,饥饿仔鱼的全长、体长、肛前长、体高等指标与摄食组差异极显著(P0.01),多项生长指标出现负增长,饥饿组与摄食组仔鱼开鳔率及鳔体积差异明显,表明饥饿对仔鱼生长发育起延迟作用。太平洋鳕仔鱼初次摄食率为30%,第7天初次摄食率达90%,仅保持1d。太平洋鳕仔鱼的耐饥饿能力较差,PNR为9日龄。最佳投饵时间为5—7日龄。  相似文献   

6.
哲罗鱼仔鱼饥饿实验及不可逆生长点的确定   总被引:3,自引:0,他引:3       下载免费PDF全文
在水温10-12℃条件下,研究了哲罗鱼Hucho taimen仔鱼饥饿对其生长、形态和行为的影响,确定其初次摄食饥饿不可逆点(PNR)和最佳初次摄食时间.结果表明:饥饿状况下哲罗鱼仔鱼全长基本维持恒定,但肥满度不断降低,在第24日龄后体重出现负增长,其卵黄囊吸收与生长变化密切相关;饥饿后的仔鱼身体发黑、头大身瘦、后脑部下陷;集群性、初次摄食力与饥饿时间呈负相关;25日龄出现自残现象,30日龄自残率达到最大值14.5%.哲罗鱼仔鱼初次摄食时间在21日龄,当29日龄摄食率达到最高值100%,PNR期为39-40日龄;初次摄食仔鱼最佳投喂时间在25日龄,也就是仔鱼上浮后第4天.  相似文献   

7.
温度对黄颡鱼仔鱼摄食强度及饥饿耐受力的影响   总被引:9,自引:0,他引:9  
对不同温度下黄颡鱼仔鱼的摄食强度及抵达不可逆点(PNR)时间的变化进行初步研究。结果表明,黄颡鱼仔鱼的摄食强度随温度升高而增大;仔鱼抵达PNR的时间随温度升高而缩短,在24~28℃下,仔鱼的PNR点出现在出膜后的7~8 d。实验结果显示,28℃是比较适宜黄颡鱼仔鱼生长的水温。  相似文献   

8.
饥饿对食蚊鱼仔鱼摄食、生长和形态的影响   总被引:6,自引:0,他引:6  
本文研究了饥饿胁迫下食蚊鱼仔鱼的摄食、生长和外部形态的变化规律.结果表明,在水温(28.5±1.2)℃时,仔鱼产出2h后鳔完成充气即建立巡游模式并开始觅食,摄食比率迅速达到100%,其混合营养期仅有4h.实验期间,投喂组仔鱼的摄食比率一直保持在100%;饥饿组仔鱼在饥饿0-3d内初次摄食比率同样可达到或接近100%,但第4天开始下降,第6天初次摄食比率降至0,抵达饥饿不可逆点(PNR)时间为产出后第5.5天左右.投喂组初产仔鱼对1-2龄期库蚊幼虫的摄食强度为(2.9±1.4)ind/individual·h,摄食强度随日龄显著增长;饥饿组仔鱼在饥饿0-5d内其初次摄食强度也随日龄及饥饿时间的延长显著增长,但均显著低于相应日龄的投喂组仔鱼,其初次摄食比率与初次摄食强度之间并无显著相关关系.饥饿仔鱼在PNR前约1.5d时其累计死亡率已超半数,达(64.4±18.1)%,抵达PNR后数小时内残存个体全部死亡.实验结束(6d)时投喂组仔鱼5项生长指标呈不等速增长,其中体重增长最为显著,瞬时增长率达0.0275/d,此时腹鳍发育基本完备,进入幼鱼期.而同期饥饿组仔鱼形态发育停滞,多项生长指标出现负增长,其中体高负增长最为明显,其瞬时增长率为-0.0511/d;体重次之,体长负增长则不甚明显.饥饿仔鱼在接近或处在PNR期时腹部萎缩呈弧形,体长/体高>5,而同期投喂组仔鱼体长/体高<4.5,两者差异显著,可作为鉴别饥饿仔鱼和健康仔鱼较理想的形态数量指标.  相似文献   

9.
延迟投饵对史氏鲟仔鱼摄食、存活及生长的影响   总被引:11,自引:0,他引:11  
为了解史氏鲟仔鱼阶段的开口摄食习性,为史氏鲟的人工育苗提供基础资料,研究了延迟投饵对史氏鲟仔鱼摄食、存活及生长的影响。结果表明:仔鱼6日龄开口,7日龄史氏鲟仔鱼初次摄食,10日龄卵黄基本吸收完毕,16~17日龄,不能建立外源性营养的仔鱼进入饥饿的不可逆点(PNR)期,故其PNR是16日龄;史氏鲟仔鱼存活率随延迟投饵天数的增加而降低,6日龄后,延迟投饵时间在7d内,仔鱼存活率可达60%以上,延迟投饵时间在8~10d内,仔鱼的成活率下降至40%左右,延迟投饵时间为11d,存活率下降至10%,延迟投饵时间为12d及以后,存活率为0;史氏鲟仔鱼全长和体质量在延迟投饵4d内均增加;延迟投饵超过4d则均下降。延迟投喂时间在8d以内,仔鱼全长和体质量与对照组无显著性差异;延迟投喂超过9d,全长和体质量低于对照组;史氏鲟仔鱼适宜投饵的时间是孵出后9~10d。  相似文献   

10.
利用采自赤水河下游的银鮈(Squalidus argentatus)鱼卵对其早期发育进行了观察和描述,并对仔鱼的耐饥饿能力进行了研究。银卵属中等大小的漂流性卵,具双层卵膜,外膜径(3.35±0.41)mm。胚胎发育分32个发育期,在水温24.6~25.5℃时历时40h。初孵仔鱼全长(3.84±0.36)mm,眼下有一个黑点,胸鳍原基已形成,经85d左右发育成幼鱼。仔鱼孵出后2~3d开口摄食,5日龄时初次摄食率即达100%。持续饥饿对银鮈仔鱼生长、发育、存活均有很大影响,饥饿仔鱼11~12d达不可逆点(PNR),饥饿至13日龄时,绝大部分仔鱼死亡。  相似文献   

11.
The effects of the timing of initial feeding (0, 1, 2, 3 and 4 days after yolk exhaustion) and temperature (15, 18 and 21° C) on the point‐of‐no‐return (PNR), survival and growth of laboratory‐reared Japanese flounder Paralichthys olivaceus larvae were studied under controlled conditions. The larvae reached PNR on 7·7, 5·2 and 4·2 days‐post‐hatching (dph) at 15, 18 and 21° C, respectively. At each temperature, larval growth did not differ significantly among the delayed initial feedings 1 day before PNR but decreased significantly in larvae first fed after that. In the treatments where initial feeding was equally delayed, larvae grew significantly faster at 18 and 21° C than at 15° C. The larvae survived apparently better at 15 and 18° C than at 21° C when initial feeding was equally delayed. At each temperature, survival of the larvae first fed before PNR did not differ noticeably, while delayed initial feeding after that apparently reduced their survival. These results indicated that there existed a negatively temperature‐dependent PNR in the Japanese flounder larvae. Survival and growth of the larvae strongly depended on temperature as well as the timing of initial feeding. High temperature accelerated the yolk exhaustion and growth of the larvae and thus reduced their starvation tolerance and survival. To avoid potential starvation mortality and obtain good growth, the Japanese flounder larvae must establish successful initial feeding within 2 days after yolk exhaustion at 15° C and within 1 day at both 18 and 21° C.  相似文献   

12.
We investigated the effects of the timing of first feeding (larvae in F0, F1, F2, F3 and S were first fed on day 3, 4, 5, 6 days after hatching (DAH) and unfed, respectively) on feeding, morphological changes, survival and growth in miiuy croaker larvae at 24°C. The fed larvae initiated feeding on 3 DAH and reached point of no return (PNR) on 6 DAH. Larvae in F0 and F1 groups survived apparently better than F2 group at the end of the experiment on 36 DAH. High larval mortality occurred from 3 to 7 DAH in all feeding groups, accounting for 40% (F0, F1 and F2 groups) to 90% (F3 and S groups) of the total mortality. Larvae in F0 and F1 groups grew better than F2 group throughout the experiment. Eye diameter, body height, head height and mouth gape of the first feeding larvae were more sensitive to starvation than other morphometrics and could be used as indicators for evaluating their nutritional status. Results indicated that delayed first feeding over 1 day after yolk exhaustion could lead to poor larval survival and growth. To avoid starvation and obtain good growth in culturing, larvae feeding should be initiated within 1 day after yolk exhaustion at 24°C.  相似文献   

13.
Synopsis The capability of unfed walleye pollock, Theragra chalcogramma, larvae to swim horizontally towards light was used as a sensitive, sublethal measure of larval condition. At 9°C, positive phototaxis and swimming ability of larvae was fully developed by 4–6 d after hatching, then decreased steadily until death by 12 d after hatching. This measure of larval condition corresponded closely with previously established benchmarks of larval condition, including first feeding, yolksac absorption, point of no return and death by starvation. The presence and timing of behavioral deficits associated with starvation, such as decreased ability to swim, feed and avoid predators, may have significant effects on the ability of larvae to vertically migrate, avoid predators and find and capture food.  相似文献   

14.
The effects of individual larval biomass, and salinity experienced during embryogenesis (i.e., prehatching salinity) on starvation tolerance and growth of zoea 1 of the estuarine crab (Chasmagnathus granulata) were evaluated in laboratory experiments. Freshly hatched zoeae 1 were obtained from broods maintained at three salinities (15‰, 20‰ and 32‰), and cultured at 20‰ under different initial feeding periods and subsequent food deprivation (“point of reserve saturation” experiment: PRS) or under initial periods of food deprivation and subsequent feeding (point of no return experiment: PNR). Another group of larvae were used for determination of biomass (dry weight, carbon, and nitrogen) of zoea 1.Larval survival and duration of development depended on the length of feeding period: no larvae reached the second instar under complete starvation; survival was higher and duration of development shorter as the feeding period lengthened. After different initial feeding periods (PRS experiment), zoeae 1 that hatched from eggs incubated at the prehatching salinities of 15‰ and 20‰ showed higher survival and shorter duration of development than those at 32‰. Prehatching salinity also affected the amount of reserves accumulated during the first 2 days after hatching, with larvae from 15‰ and 20‰ showing the highest percentage of total accumulation of carbon and nitrogen. Initial larval biomass did not affect survival, but it had a slight effect on duration of development, with larger larvae (in terms of biomass) developing faster. After different initial starvation periods (PNR experiment), prehatching salinity did not affect survival, but it affected duration of development: larvae from 15‰ and 20‰ reached the second instar earlier. Variability in survival and duration of development was explained in part by among-brood variability in initial larval biomass: larvae with higher biomass showed higher survival and shorter duration of development. Thus, C. granulata, survival and duration of development under food stress depend on the interaction between environmental conditions experienced before and after hatching (pre- and posthatching factors, respectively).  相似文献   

15.
微流水培养条件下斑鳜仔鱼的摄食与生长   总被引:1,自引:0,他引:1       下载免费PDF全文
在孵化环道连续微流水培养、水温(24±2)℃条件下,斑鳜(Siniperca scherzeri Steindachner)初孵仔鱼全长为(4.87±0.10)mm(n=50),卵黄囊体积为(1.461±0.172)mm3(n=50),油球直径为(0.47±0.04)mm(n=50).仔鱼孵出12h,胸鳍增大,具有一定阵发性水平游动能力,1日龄巡游模式建立;2日龄口膜消失,开始主动摄食,进入混合营养期,3 日龄外源性摄食关系完全建立.5日龄仔鱼的卵黄和油球全部消失.进入外源营养期;15日龄全长达到(13.72±0.76)mm(n=12).仔鱼发育过程中,其全长生长存在内源性营养阶段的较快速生长,混合营养阶段的慢速生长以及外源性营养阶段的快速生长三个生长期相,平均增长率为0.59 mm/d,对仔鱼全长TL(mm)与日龄D(d)进行同归,其生长模型为:TL=-0.0004D3+0.0283D2+0.2159D + 4.9335(R2=0.985,n=261).2-15 日龄,口宽与全长呈正比关系.仔鱼从初孵到PNR仅为5-6d,具有摄食能力的时间4d,仔鱼依赖外源性营养开始时间较早,对饥饿的耐受力较差.  相似文献   

16.
Effects of feeding and starvation on the moult cycle and on the ultrastructure of hepatopancreas cells were studied in Stage I lobster larvae (Homarus americanus Milne-Edwards). The relative significance of yolk and first food was quite different in larvae originating from two females. This difference was evident also in the amounts of stored lipid in the R-cells of the larval hepatopancreas. Most larvae from one hatch were, in principle, able to develop exclusively with yolk reserves (without food) to the second instar. The larvae from the second hatch showed lecithotrophic development only to the transition between late intermoult and early premoult (Stages C/D0 of Drachs's moult cycle) of the first larval instar. When initial starvation in this group lasted for 3 days or more, the point of no return (PNR) was exceeded. After the PNR, consumption of food was still possible, but development ceased in the transition C/D0 or in late premoult (D3–4). It is suggested that these stages of the moult cycle are critical points were cessation of development and increased mortality are particularly likely in early larval lobsters under nutritional stress. Examination of hepatopancreas R-cells suggested that the PNR is caused by an irreversible loss of the ability to restore lipid reserves depleted during initial starvation. Initial periods of starvation ending before the PNR prolonged mainly Stage D0 of the same instar (I). During this delay, structural changes in the R-cells caused by the preceding period of starvation were reversed: reduced lipid inclusions, swollen mitochondria, an increased number of residual bodies indicating autolysis, and a reduction of the microvillous processes. Continually starved larvae which showed lecithotrophic development throughout the first instar and were then re-fed after moulting successfully, had later a prolonged intermoult (Stage C) period in the second instar. This shows that, despite occasional lecithotrophy, food is an important factor in early larval development of the lobster.  相似文献   

17.
Development of embryos and larvae in Ancherythroculter nigrocauda Yih et Woo (1964) and effects of delayed first feeding on larvae were observed after artificial fertilization. The fertilized eggs were incubated at an average temperature of 26.5°C (range: 25.7–27) and the larvae reared at temperatures ranging from 21.8 to 28°C. First cleavage was at 50 min, epiboly began at 7 h 5 min, heartbeat reached 72 per min at 24 h 40 min and hatching occurred at 43 h 15 min after insemination. Mean total length of newly hatched larvae was 4.04 ± 0.03 mm (n = 15). A one‐chambered gas bladder was observed at 70 h 50 min, two chambers occurred at 15 days, and scales appeared approximately 30 days after hatching. Larvae began to feed exogenously at day 4 post‐hatch at an average temperature of 24°C. Food deprivation resulted in a progressive atrophy of skeletal muscle fibres, deterioration of the larval digestive system and cessation of organ differentiation. Larval growth under food deprivation was significantly affected by the time of first exogenous feeding. Starved larvae began to shrink, with negative growth from day 6 post‐hatch. The point of no return (PNR) was reached at day 11 after hatching. Mortality of starved larvae increased sharply from day 12 after hatching.  相似文献   

18.
Abstract

One of the key factors affecting larval survival is food availability. This study investigated the influence of starvation on the nutritional condition of zoea I larvae of Pleuroncodes monodon. Experimental treatments with differential periods of starvation and subsequent feeding (point of no return: PNR) in addition to treatments with differential periods of feeding and subsequent starvation (point of reserve saturation: PRS) were used to quantify larval survival and the occurrence of lipid droplets in the hepatopancreas. Larval survival differed significantly depending on the starvation and feeding treatment administered. A high percentage of survival was found for the starvation treatment until day 1 (S1-PNR), for the feeding treatment until day 4 (F4-PRS), and for the continuously fed control groups (FC). Survival was minimal for the starvation treatment lasting until day 7 (S7-PNR) and for the continuously starved control groups (SC). In turn, similar tendencies were observed in the utilization of energy reserves; the lipid droplets significantly decreased throughout the PNR treatment, while the presence of lipid droplets gradually increased during the PRS treatment. All these larval condition parameters can be used in fishery models of population dynamics, which estimate the nutritional status of the offspring and their effects on survival.  相似文献   

19.
幼虫期短时高温暴露对二点委夜蛾存活和繁殖的影响   总被引:3,自引:0,他引:3  
【目的】随着全球气候变暖,夏季短时极端高温发生的频率逐渐增加。本研究旨在探明二点委夜蛾Athetis lepigone幼虫期对高温的适应性。【方法】将二点委夜蛾不同日龄(1,6,12和18日龄)幼虫在不同高温(35,38和41℃)条件下暴露不同时间(0.5,1,2,4和6 h)后转移至适温(26℃)继续饲养,观察短时高温对其存活率、发育历期、化蛹率、羽化率、雌虫寿命、单雌产卵量及次代卵孵化率的影响。【结果】幼虫期短时高温暴露的温度和时间对二点委夜蛾幼虫的存活率和发育历期有显著影响,而对化蛹率、成虫羽化率、雌虫寿命、单雌产卵量以及次代卵孵化率影响不显著。随着温度的升高和处理时间的延长,幼虫存活率逐渐降低,发育历期逐渐延长。其中,18日龄的幼虫最为敏感,38℃和41℃暴露6 h后存活率分别为58.3%和17.7%,显著低于对照,发育历期分别为25.5 d和29.2 d,较对照显著延长。【结论】幼虫期经历短时高温暴露仅对幼虫的存活和发育历期有影响,而对后续蛹和成虫的生长发育及成虫繁殖力没有影响。  相似文献   

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