不同光照条件下叉尾斗鱼仔鱼摄食节律

在自然光照、持续光照和持续黑暗3种光照条件下,研究了孵化后第5、8和12日龄的叉尾斗鱼仔鱼的摄食节律。结果表明:自然光照下,3个日龄的叉尾斗鱼仔鱼在午后12:00—16:00表现出明显的摄食高峰,而持续光照组与持续黑暗组未表现出明显的摄食峰谷。持续光照下,叉尾斗鱼仔鱼的昼夜摄食活动均很活跃,全日各时段平均摄食量显著增加,尤其是夜晚20:00—翌日4:00各时段平均摄食量极显著高于同一时段自然光照组。而在持续黑暗下,与自然光照相比全日各时段平均摄食量明显减少,尤其是白天8:00—16:00各时段的平均摄食量极显著降低。叉尾斗鱼仔鱼属于典型的白天摄食类型,其摄食节律与光照条件密切相关。     

云斑尖塘鳢消化酶活力的研究

本文采用酶学分析方法研究了云斑尖塘鳢在正常摄食状态与饥饿的状态下胃、肠及肝胰脏组织中蛋白酶、淀粉酶和脂肪酶的活性。结果显示,在30℃的条件下,正常摄食组样本在酸性条件下的蛋白酶活力表现为:胃后肠肝胰脏前肠,中性和碱性条件下:后肠肝胰脏前肠及胃;饥饿组样本仅有胃表现出较高的酸性蛋白酶活性,其他器官的蛋白酶活性均很低。在正常和饥饿实验组中肝胰脏的淀粉酶活性均高于其他器官,胃肠的淀粉酶活性均较低。正常摄食组中脂肪酶活力后肠肝胰脏;而在饥饿组中仅有肝胰脏检测到脂肪酶活性。结果表明,云斑尖塘鳢适度饥饿组较正常摄食组消化酶活性大幅降低;其高蛋白酶活力及中等脂肪酶活力与其肉食性相一致;此外云斑尖塘鳢也具备少量的淀粉消化能力。     

云斑尖塘鳢胚胎和早期仔鱼的发育

对云斑尖塘鳢(Oxyeleotris marmoratus)胚胎和早期仔鱼的发育进行了观察,详细描述了各发育阶段的形态特征。在28℃定水温条件下,云斑尖塘鳢的胚胎发育历时80h 30min,可分为24个发育分期。在整个发育过程中,眼、耳囊、心脏、消化道、肾脏、鳔、胸鳍和尾鳍等得到了优先发育。     

不同光照周期下鲇仔鱼的日摄食节律

水温23±1℃时,对鲇仔鱼自然光照、持续光照和持续黑暗下的日摄食节律研究表明,3种光照周期下,鲇仔鱼有明显的日摄食节律.持续光照与自然光照的日摄食节律基本一致,但持续黑暗与自然光照的日摄食节律不同;鲇仔鱼在自然及持续光照周期下均属典型的夜晚摄食类型,而在持续黑暗周期下不属于此类型;光照周期的改变对鲇仔鱼日摄食率的影响显著(P<0.05).     

池养条件下似刺鳊鮈早期发育阶段的摄食与生长特性

对人工培育的似刺鳊鮈（Paracanthobrama guichenoti）仔鱼、稚鱼和幼鱼的生长与摄食节律进行了研究。结果显示,在1～70日龄间,似刺鳊鮈全长平均日增长率为3．55％,体重平均日增长率为11．26％,头长／全长值随着日龄的增长而变小。全长（L,mm）与体重（M,mg）的关系式为M=O．0012L^2-0．0564L＋0．6504;体重（M,mg）与日龄（D,d）的关系式为M=O．0043e^0.0936D;全长（L,mm）和日龄（D,d）的关系式为L=0．0154D^2-0．0128D＋8．1965。在饵料充足的条件下,20日龄晚期仔鱼全天均有很高的摄食发生率,小高峰出现在8：00时;40日龄稚鱼则表现出明显的昼夜摄食节律,属于典型的白天摄食类型,日摄食率2．3376％。20日龄仔鱼和4013龄稚鱼饱食后分别经6h、5h整个消化道排空。在水温25℃及饥饿空胃状态下,10日龄仔鱼只经3d即开始出现死亡个体,经5d全部死亡;20日龄仔鱼经6d开始出现死亡个体,经9d全部死亡;40日龄稚鱼经7d才开始出现死亡个体,10d后全部个体均死亡。     

池养条件下似刺鳊(鱼句)早期发育阶段的摄食与生长特性

对人工培育的似刺鳊(鱼句)(Paracanthobrama guichenoti)仔鱼、稚鱼和幼鱼的生长与摄食节律进行了研究.结果显示,在1~70日龄间,似刺鳊(鱼句)全长平均日增长率为3.55%,体重平均日增长率为11.26%,头长/全长值随着13龄的增长而变小.全长(L,mm)与体重(M,mg)的关系式为M=0.001 2 L2-0.056 4L+0.650 4;体重(M,mg)与日龄(D,d)的关系式为M=0.004 3 e0.0936D;全长(L,mm)和日龄(D,d)的关系式为L=0.015 4 D2-0.012 8 D+8.196 5.在饵料充足的条件下,20日龄晚期仔鱼全天均有很高的摄食发生率,小高峰出现在8:00时;40日龄稚鱼则表现出明显的昼夜摄食节律,属于典型的白天摄食类型,日摄食率2.337 6%.20 13龄仔鱼和40日龄稚鱼饱食后分别经6 h、5 h整个消化道排空.在水温25℃及饥饿空胃状态下,10日龄仔鱼只经3 d即开始出现死亡个体,经5 d全部死亡;20日龄仔鱼经6 d开始出现死亡个体,经9 d全部死亡;40 13龄稚鱼经7 d才开始出现死亡个体,10 d后全部个体均死亡.     

尖塘鳢属鱼类线粒体12SrRNA基因序列分析

利用PCR技术扩增和测序了线纹尖塘鳢、云斑尖塘鳢和海丰沙塘鳢线粒体12SrRNA基因,结合从GenBank中下载的部分同源序列,共分析了5种鱼类的系统发育关系。在Kimura2-parameter模型构建的邻接树中,原产泰国的云斑尖塘鳢与原产澳州线纹尖塘鳢均为单系类群,二者为亲缘关系最为密切的姐妹群,海丰沙塘鳢与其它群体的亲缘关系较远,支持将尖塘鳢属从塘鳢属中分出的传统分类处理。尖塘鳢属内云斑尖塘鳢和线纹尖塘鳢鱼类种内DNA序列无差异,而种间差异明显,表明线粒体12SrRNA基因可作为塘鳢科鱼类种类鉴定的良好分子标记。     

线纹尖塘鳢仔、稚鱼的形态发育

对池养条件下线纹尖塘鳢(Oxyeleotris lineolatus)的胚后发育进行定期观察,胚后发育大致可分为前期仔鱼、后期仔鱼、稚鱼和幼成鱼期。观察发现,线纹尖塘鳢的初孵仔鱼个体较小,仅2.875mm,前期仔鱼,包括混合营养仔鱼期,时间短,仅为5d,属较早建立起外源性营养摄食机制的鱼类;器官发育主要在后期仔鱼阶段完成;鳞的出现和鳞被形成在稚鱼发育阶段完成;在池塘自然水温26~30℃条件下,从初孵仔鱼到稚鱼发育期完成历时43~44d。     

食蚊鱼摄食特性及其与浮游动物和环境因子的关系

2008年11月—2009年4月,利用分时段采样法对广州暨南大学明湖内食蚊鱼在秋季(11月)、冬季(12—2月)、春季(3—4月)3个季节的摄食特性进行了研究,探讨其与湖内浮游动物群体数量动态、光照和水温的关系。结果表明:食蚊鱼主要以浮游动物为食,对枝角类和桡足类有较强的选择性;明湖日平均水温与浮游动物日平均丰度在3个季节间有显著差异,而食蚊鱼消化道饱满指数的差异不显著;食蚊鱼消化道饱满指数在这3个季节的变化与浮游动物丰度、水温、光照在这3个季节的变化无明显的相关;无论哪个季节,食蚊鱼在白天时段(10:00—18:00)的消化道饱满指数均高于夜间(22:00—6:00),表现出白天高峰型的摄食节律;光照是影响食蚊鱼昼夜摄食节律的主要因素,而水温、浮游动物丰度的昼夜变化与食蚊鱼的昼夜摄食节律没有显著相关。     

人工养殖云斑尖塘鳢的生长特性

研究了人工养殖条件下云斑尖塘鳢（Oxyeleotris marmoratus）的生长特性。结果表明：经过2个月的生长期,云斑尖塘鳢的平均体长从最初的（17．36&#177;0．99）cm增加到（19．05&#177;0．57）cm,体质量从（139．13&#177;12．90）g增加到（205．50&#177;15．78）g,体长增加10％,体质量增加48％。不同的养殖时间除对摄食率（FR）无显著影响外（P〉0．05）,对特定生长率（SGR）、饵料转化效率（FCR）和生长效率（GE）都有显著影响（P〈0．05）。体长生长与时间表现为线性相关,体质量生长与时间表现为指数相关。云斑尖塘鳢体质量与体长之间呈幂函数关系,不同养殖时间下,幂指数b值都接近3,表明云斑尖塘鳢的体长和体质量呈等速生长。     

军曹鱼(Rachycentron canadum)早期发育阶段的摄食及其影响因子*

研究了军曹鱼(Rachycentron canadum)仔、稚鱼的日摄食节律和摄食强度,以及饵料密度、温度、盐度对其摄食的影响。结果表明,发育8d仔鱼(摄食轮虫)、23d稚鱼(摄食卤虫无节幼体)和38d稚鱼(摄食鳗鱼粉状饵料)均表现为明显的昼夜摄食节律,摄食主要在白天进行,白天摄食强度占日摄食强度的68%以上;在白天的摄食中,又以早晨6:00-8:00和傍晚16:00-18:00摄食强度最大:夜间摄食较少或基本不摄食,所以军曹鱼早期幼体的摄食习性属白天摄食且偏于晨昏性类型。在不同饵料密度梯度的试验中,发育8d-11d仔鱼和23d-26d稚鱼摄食的适宜饵料密度范围分别为15ind·mL^-1-20ind·mL^-1和7ind·mL^-1-2ind·mL^-1。温度和盐度对发育21d-24d稚鱼日摄食强度的影响均表现为抛物线型的变化曲线,摄食的适宜水温范围为27-31℃,适宜盐度范围为28‰-32‰。结果还表明,幼休摄食强度与饵料密度、水温、盐度的关系均适合于用二次多项式来定量描述。     

Cholecystokinin (CCK) in Atlantic herring (Clupea harengus L.) - ontogeny and effects of feeding and diurnal rhythms

Neural and alimentary cholecystokinin (CCK) levels in Atlantic herring, Clupea harengus, were analyzed from hatching to 40days after hatching (DAH). The head compartment representing the neural pool was quantitatively dominant (>80% of the total CCK content) while the digestive tract pool represented 6-10%. During ontogeny the CCK level in whole larvae increased almost 15-fold from 0 to 40 DAH, being particularly marked from 14 to 20 DAH. Larvae of 24 to 26 DAH were examined for potential occurrence of a circadian rhythm and to analyze the effects of feeding. Fed and fasted larvae were significantly different, where fed larvae showed higher CCK levels. There were large fluctuations in CCK levels analyzed at 3h intervals without an apparent diurnal pattern. Shorter sampling intervals of 1h in the morning when lights were switched gradually on and food was offered to the larvae demonstrated a marked drop in the relative gut CCK levels and a concurrent increase in the CCK carcass to gut ratio, 1h after introduction of food followed by a return to prefeeding levels after 2h. This response probably results from a release and re-synthesis of CCK in the gut after initiation of feeding. Taken together, these results support earlier reports that CCK participates in the regulation of digestive processes in herring larvae, but CCK does not seem to have a circadian rhythm independent of feeding.     

Feeding resumption, morphological changes and mortality during starvation in Japanese flounder larvae

Japanese flounder Paralichthys olivaceus larvae established first feeding 3 days after hatching (DAH) at c . 17° C. Non-fed fish reached irreversible starvation at age 5 DAH. Non-fed fish showed similar feeding rate and feeding intensity as the fed fish when they were provided with prey before 5 DAH, after which the starved larvae did not feed even when prey became available. None of the six morphological measurements examined (total length, body height, eye height, head height, gut height and myotome height) showed significant differences between the non-fed and fed larvae until 5 DAH. Normal development continued only in the fed group, and the non-fed larvae showed reverse growth or body collapse after 5 DAH. Owing to the shrinkage and collapse at the top of head due to starvation, head height could be a sensitive indicator of starvation in Japanese flounder larvae. In the fed treatments, high mortality occurred from first feeding (3 DAH) to irreversible starvation (5 DAH), accounting for about two-thirds to three-quarters of the overall mortality (46–52%) throughout the experiments. This mortality was not prey density or larval density dependent. Mortality during the same period in the non-fed larvae accounted for about a third of the overall mortality (100%).     

First feeding and subsequent growth performances in piscivorous larvae of Chinese perch Siniperca chuatsi (Perciforms: Sinipercidae)

The success of first feeding is influenced by many factors, such as prey availability, and is critical to subsequent larval growth performances. To test the advantages of prey exposure before complete yolk absorption in piscivorous larvae, feeding incidence and specific growth rate were longitudinally measured in Chinese perch Siniperca chuatsi larvae first fed at different ages. The results showed that Chinese perch larvae were able to capture live piscine prey at 4 DAH (days after hatching), 1 day before complete yolk absorption. The feeding incidence and specific growth rate were higher in larvae first fed at 4 DAH than in larvae first fed at 5 or 6 DAH. These results indicate that prey exposure experience can facilitate the onset of first feeding, and that successful exogenous feeding, even before complete yolk absorption, is important for growth performances of piscivorous fish larvae.     

黑斑原仔稚鱼藏匿行为研究

文章研究了黑斑原(Glyptosternum maculatum)仔稚鱼对缝隙的喜好行为、对底质颜色及种类的选择行为,旨在优化苗种培育模式,改善其养殖条件。结果表明:黑斑原仔稚鱼对缝隙的喜好日间(7:00—20:00)显著高于夜间(21:00—6:00; P<0.05);开口22d、23d和25—30d对缝隙无喜好行为(P>0.05),且夜间(开口6d、11—13d除外)对缝隙无喜好行为(P>0.05);开口12d、13d、15d和24d仔稚鱼表现出对较小缝隙(0.9 cm)的喜好性(P<0.05);开口2d和3d仔稚鱼表现出对底层缝隙的喜好性(P<0.05);开口5d、6d、8—21d和24d仔稚鱼表现出对表层缝隙的喜好性(P<0.05);在(400±50) lx光补偿条件下仔稚鱼对底质颜色无明显的喜好性;在(10±2) lx光补偿条件下仔稚鱼对黑色底质的喜好性显著于白色底质(P<0.05)。仔稚鱼日间具有较强的藏匿行为,喜好藏匿于较小的缝隙中,并在弱光补偿条件下喜好黑色底质。仔稚鱼的藏匿特点,为优化苗种培育和改善苗种培育环境提供了重要的...     

Effects of the timing of initial feeding on growth and survival of spotted mandarin fish Siniperca scherzeri larvae

The effects of delayed first feeding on growth and survival of spotted mandarin fish Siniperca scherzeri larvae were examined under controlled conditions. Morphometric characters [yolk‐sac volume, oil globule volume, head depth (H_D), body depth (B_D), eye diameter (E_D), musculature height (M_H), mouth diameter (M_D) and total length (L_T)], body mass (M), specific growth rate (S_GR) and survival were evaluated under different first‐feeding time (2, 3, 4 and 5 days after hatching). Larvae began to feed exogenously at 2 days after hatching (DAH) and the point of no return (P_NR) occurred between 5 and 6 DAH at 23° C, range ±1·0° C. The yolk volume of larvae first‐fed at 2 days had a significant difference compared with that of larvae first‐fed at 3, 4 and 5 days on 3 and 4 DAH. The larvae first‐fed at 2 days achieved comparatively better growth performance than that of 3, 4 and 5 days. On 5 DAH, all morphometric characters had significant differences between 2 and 5 days and 2 and 4 days initial feeding, respectively. Total mortality was recorded on 9 DAH for the larvae first‐fed at 5 days. On 12 DAH, significant differences were observed between 2 and 4 days and 3 and 4 days initial feeding for all morphometric characters. From 16 DAH to the end of experiment, all growth variables of the larvae first‐fed at 2 days were significantly higher than those in other treatments. The S_GR (2–9 DAH) first‐fed at 2 and 3 days were significantly higher than 4 and 5 day treatments, and the S_GR (9–16 DAH) first‐fed at 2 days was significantly higher than 3 and 4 day treatments. There was no significant difference, however, of S_GR (16–28 DAH) among treatments. Survival rate was significantly higher at 2 days initial feeding (27·42%) when compared with 3 (15·96%) and 4 days (7·92%) initial feeding at the end of experiment. The present study suggests that the first feeding of S. scherzeri larvae should be initiated at 2 days after hatching for achieving good growth and survival.     

Circadian rhythm of serum testosterone levels in male beagle dogs--effects of lighting time zone

In a previous study, the author found that serum testosterone (T) levels in male beagle dogs showed a circadian rhythm which was lowest at 12:00, and increased to a peak at 18:00-6:00, thereafter decreasing until 12:00. The reason was thought to be that dogs were breeding under rigid controlled conditions. The present study was performed to investigate the effects of lighting on the circadian rhythm of T level by means of a reversal of the lighting time zone, because lighting is considered an important factor in modulating T levels. Six male beagle dogs of 2 years were used in this study. The routine lighting time (8:00-20:00) and dark time (20:00-8:00) zone in the breeding room was reversed completely and T levels were measured at intervals of 1-5 weeks for up to 54 weeks. Blood samples were collected at 6:00, 12:00, 18:00 and 24:00. The results showed that the circadian rhythm of the T level and the T level at each blood sampling time did not change significantly within 54 weeks. As a result, it was recognized that the circadian rhythm of the T level in male dogs may not be affected by changes in the lighting time zone.     

光照对大泷六线鱼仔鱼摄食量的影响

对不同照度下大泷六线鱼仔鱼摄食量进行了初步测定,得知仔鱼在１００Ｌｘ时摄食量最大,其次为１０Ｌｘ,摄食率为１００Ｌｘ时最高,并在２０分钟时达到最大值,可见大泷六线仔鱼的适宜照度范围为１０－１００Ｌｘ,高或低于此照度都会影响仔鱼的摄食效果。     

微流水培养条件下斑鳜仔鱼的摄食与生长

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.     

食蚊鱼昼夜摄食节律观察

以分时段采样法研究入侵物种食蚊鱼的夏季昼夜摄食节律。食蚊鱼夏季种群内有雌鱼、雄鱼和幼鱼三个不同的摄食类群,这三个类群的摄食节律差异明显。雌鱼摄食节律成双峰型,第一高峰在10:00,而最高峰在22:00,此时肠道食物团平均重量11.70±11.60mg,饱满指数为190.22±155.61。幼鱼也成双峰型,分别在6:00和18:00有两个摄食高峰,以清晨6:00为最高,肠道食物团平均重1.08±1.09mg,饱满指数为128.44±105.49。雄鱼则成单峰型,摄食高峰出现午后14:00左右,肠道食物团平均重0.71±0.96mg,饱满指数为71.80±107.65。食蚊鱼不同摄食类群间的摄食高峰交错出现,是其协调种内关系,降低种内竞争的一种有效行为机制。