沙氏下鱵鱼仔鱼的摄食能力和营养代谢

20 0 0年 6月 18日 14 :2 0时在 35°0 0′N、 12 1°0 0′E海域利用大型浮游生物网采集了大量的沙氏下鱼天然受精卵 ,将受精卵置于新鲜的海水中进行人工孵化 ,7月 1日 8时仔鱼开始孵出 ,0 5h后收集大约 5 0 0尾初孵仔鱼条进行饥饿试验。在培养水温为 2 4 2～ 2 4 8℃条件下 ,沙氏下鱼仔鱼孵化后 1h就建立起巡游模式 ,4h就具有非常高的初次摄食率和摄食强度 ,仔鱼的混合营养期为 2d ,具有初次摄食能力的时间为 3d ,饥饿不可逆转点发生在孵化后大约 3 5d ,不可逆点 (PNR)期仔鱼没有出现胸角这一形态学特征。沙氏下鱼仔鱼这么短的时间建立巡游模式 ,对仔鱼在混合营养期这一有限的时间内顺利地建立起外源性摄食关系 ,在时间上取得了一定的保障作用 ,对种群的繁衍策略具有一定的生态学意义 ,说明在仔鱼的初次摄食阶段 ,自然海区中适合于仔鱼摄食的饵料生物的种类、分布与数量对其早期的成活是至关重要的。PNR期仔鱼是否具有胸角以及胸角是否为仔鱼的饥饿体征因种而异 ,在渔业资源生态调查的仔鱼样品的鉴别工作中 ,应用仔鱼的胸角鉴别健康仔鱼和饥饿仔鱼时应因种而论.     

半滑舌鳎仔鱼的摄食与生长

在水温23.4-24.0℃、盐度33.00、pH7.78-8.02的培养条件下,半滑舌鳎初孵仔鱼全长为3.55±0.161mm(n=60),依照公式4/3π.R/2.(r/2)2计算其卵黄囊体积为0.606±0.106mm3(n=60)。1日龄仔鱼,全长为4.99±0.211mm(n=10),卵黄囊体积较初孵仔鱼缩小近10倍,约为0.066±0.008mm3(n=10);2日龄,仔鱼的巡游模式建立,仔鱼全长为5.61±0.069mm,卵黄囊体积为0.030±0.002mm3(n=10),口初开;2.5日龄,口完全裂开,口裂0.24±0.024mm(n=10),仔鱼进入摄食期;3日龄,仔鱼的外源性摄食关系初步建立;4日龄,仔鱼的摄食率达100%,完成了内源性营养向外源性营养的转换;5日龄,仔鱼的卵黄完全被吸收,仅剩聚成一团的小油球,仔鱼的混合营养期持续2.5天时间;21日龄,稚鱼全长为12.96±0.611mm(n=11),仍有40%的个体残余的油球还没有完全被吸收,其体积仅为0.0000005±0.000003mm3(n=11)。仔鱼发育过程中,其长度的生长存在内源性营养阶段的快速生长、混合营养阶段的慢速生长以及饥饿期间的负生长三个生长期相,平均增长率为0.45mm/d,依照TL=aD3 bD2 cD d方程式对仔鱼的全长与日龄进行回归,其生长模型为TL(mm)=0.0026D3-0.0704D2 0.7993D 3.55(R2=0.9811,n=324)。仔鱼耐受饥饿的时间临界点发生在孵化后第10天(即9日龄)。仔鱼具有摄食能力的时间约6天,不可逆转饥饿期的时间约3天。残余的油球较长时间的存在,相对地延长了仔鱼混合营养期的时间,对仔鱼的发育、生长和存活有着至关重要的作用。5-20日龄的个体都具有胸角这个明显的形态学特征,只是饥饿个体和不可逆转饥饿期个体的胸角比摄食个体更为明显和尖锐,胸角不能作为区分健康仔鱼和饥饿仔鱼的形态学依据之一[动物学报51(6)1023-1033,2005]。     

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.     

饥饿对唐鱼仔鱼摄食和生长的影响

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。     

温度对黄颡鱼仔鱼摄食强度及饥饿耐受力的影响

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7～8d。实验结果显示,28℃是比较适宜黄颡鱼仔鱼生长的水温。     

俄罗斯鲟仔鱼初次摄食时间对生长及存活的影响

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。     

稀有鮈鲫仔鱼的摄食和耐饥饿能力

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。     

温度对花斑副沙鳅仔鱼发育、摄食及不可逆点的影响

2011年4～5月,研究了温度对花斑副沙鳅(Parabotia fasciata)早期仔鱼的发育、初次摄食时间、群体摄食率及不可逆点(PNR)的影响。结果发现,花斑副沙鳅仔鱼出膜后2 d已开始摄食;初次群体摄食率最高值出现在卵黄囊耗尽后的1～2 d,花斑副沙鳅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:22℃时,仔鱼的PNR出现在出膜后的8.0～9.0 d;26℃时,PNR为7.0 d;28℃时,PNR为5.5 d;30℃时,PNR为5.0 d。最大初次摄食率至PNR之间为不可逆饥饿期,22℃时为3.5 d,30℃时仅为1.5 d,说明温度越高,仔鱼耐受饥饿的能力越差,越不利于仔鱼的存活。研究认为,温度对花斑副沙鳅仔鱼发育、摄食及不可逆点的影响较大;在苗种培育过程中,应根据温度确定投饵时间,适时投饵对仔鱼的成活显得尤其重要。     

太平洋鳕仔鱼饥饿实验及不可逆生长点的确定

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。     

Effects of temperature and delayed initial feeding on the survival and growth of Japanese flounder larvae

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.     

大豆品种(系)和种植密度对豆天蛾幼虫存活及生长发育的影响

豆天蛾Clanis bilineata tsingtauica Mell幼虫,是一种食用昆虫,富含蛋白质、维生素和矿质元素,具有很高的营养、药用和经济价值。了解适宜豆天蛾幼虫生长发育的大豆品种（品系）和种植密度,可为豆天蛾幼虫规模化饲养提供理论基础。研究通过设置两因素裂区实验,在10个品种（品系）大豆和2个种植密度水平下,测定豆天蛾幼虫生物学参数,明确适宜豆天蛾幼虫养殖的大豆品种（品系）和种植密度。结果表明,不同大豆品种（系）和种植密度对豆天蛾幼虫存活及生长发育均有显著影响;其中使用连151、淮豆9号、东辛3号和H0573大豆饲养的豆天蛾幼虫产量和存活率较高,虫体长度较长,发育历期较短;大青豆饲养的豆天蛾幼虫产量较低,幼虫发育整齐度较差,发育历期长。当种植密度为40 cm×30 cm时,豆天蛾幼虫存活和发育历期整齐度均显著高于种植密度40 cm×15 cm。综上所述,较适宜豆天蛾幼虫养殖的大豆品种（品系）为连151、淮豆9号、东辛3号和H0573,种植密度为40 cm×30 cm。     

Water temperature, light intensity and zooplankton density and the feeding activity of juvenile brook charr (Salvelinus fontinalis)

SUMMARY 1. The objective of this study was to evaluate the effects of zooplankton biomass (as a measure of density), fish biomass, light intensity and water temperature on the attack rate and swimming characteristics (i.e. swimming speed and angle of turn) of juvenile (1+) brook charr (Salvelinus fontinalis) in field enclosures. We used a portable underwater camera system in a series of pelagic enclosures to quantify the feeding behaviour of brook charr over a gradient of natural conditions. 2. In simple linear or non‐linear regression models we found (i) that attack rate and angle of turn were positively related to water temperature, (ii) that attack rate and swimming speed were positively related to zooplankton biomass and light intensity and (iii) that attack rate was positively related to swimming speed. In multiple regression models, fish biomass, light intensity and variance of the angle of turn accounted for 87% of the variation in attack rate. Light intensity and water temperature accounted for 86% of the variation in swimming speed. Fish gut fullness and attack rate accounted for 83% of the variation in the variance of the angle of turn executed by fish. 3. The increase in the number of attacks as zooplankton biomass increases conforms to the general positive functional response observed in other fish species. Our results also support the hypothesis that swimming speed increases with prey biomass. We did not observe a plateau in attack rate as zooplankton biomass increased. As our experiments were performed under natural biotic and abiotic conditions, factors other than zooplankton biomass might affect or limit this response, such as water temperature and light intensity. 4. Because zooplankton biomass was correlated with water temperature and light intensity, it was not possible to evaluate the independent contribution of these factors on the attack rate and swimming characteristics (swimming speeds and angle of turn) of brook charr. However, this study highlighted the impact of these factors on the feeding behaviour of juvenile brook charr when feeding in the pelagic habitat under natural conditions, and their importance in future models of optimal foraging and fish habitat quality.     

The first specimen of the Middle Triassic Phalarodon atavus (Ichthyosauria: Mixosauridae) from South China,showing postcranial anatomy and peri‐Tethyan distribution

Phalarodon atavus from the Germanic Muschelkalk Basin was previously represented only by cranial elements. Here we report a nearly complete and articulated specimen of P. atavus from the Middle Triassic Luoping Biota, Yunnan, South China. This is the first specimen of P. atavus from outside the Germanic Basin. This discovery demonstrates a peri‐Tethyan distribution of P. atavus. The new specimen is also the first one preserving the postcranial anatomy of this species, providing the opportunity to evaluate its sustained swimming ability. Inferences made on its functional morphology suggest that this species was probably adapted for active foraging. Tooth crown morphology suggests that P. atavus may have preferred externally soft prey.     

人工饲养条件下扬子鳄的营巢和产卵行为

2003~2005年,利用红外线摄像仪,对人工饲养条件下扬子鳄(Alligatorsinensis)的营巢和产卵行为进行了研究。扬子鳄在产卵前,有营造后肢落脚洞的行为;在产卵后期,一边产卵,一边覆盖。为探讨气候对营巢的影响,采用线性回归对气候和扬子鳄营巢开始时间进行分析后的结果表明,对营巢开始时间影响最大的是4月的平均气温,较高的平均气温会导致扬子鳄营巢开始时间提前。运用主成分分析饲养条件下巢址的环境因子,得出巢址的植被盖度、离水源距离等对扬子鳄的巢址利用有较大影响。