追赶和空气曝露时间对瓦氏黄颡鱼耗氧率的影响

在20℃水温条件下,对不同时间追赶(0、0.5、2.5和5min)和空气曝露(0、2.5、5、10和20min)前和恢复过程中瓦氏黄颡鱼(Pelteobag vachelli)的耗氧率进行了测定。发现经过追赶和空气曝露处理后,瓦氏黄颡鱼耗氧率立即显著上升(P<0.05),然后逐渐恢复到处理前水平。瓦氏黄颡鱼对追赶的反应远大于空气曝露。仅仅0.5min的追赶就能够诱导出瓦氏黄颡鱼的最大耗氧率(146.66mgO2/h),2.5min追赶能诱导最大过量耗氧(39.01mgO2);5min空气曝露处理能诱导最大耗氧率(113.52mgO2/h),10min处理能诱导最大过量耗氧(23.01mgO2)。     

瓦氏黄颡鱼与黄颡鱼的耗氧率及窒息点

在平均水温25℃条件下,测得平均体重10.0 g的瓦氏黄颡鱼(Pelteobagrus vachelli)及平均体重12.6g的黄颡鱼(P.fulvidraco)耗氧率分别为0.21和0.23 mg/g.h,窒息点分别为0.91和0.75 mg/L;平均体重75.8 g的瓦氏黄颡鱼及平均体重85.4 g的黄颡鱼耗氧率分别为0.16和0.12 mg/g.h,窒息点分别为0.77和0.54 mg/L。分析表明,瓦氏黄颡鱼的耗氧率和窒息点都高于黄颡鱼。     

不同游泳速度条件下瓦氏黄颡幼鱼的有氧和无氧代谢反应

在(25±1)℃的条件下,测定瓦氏黄颡(Pelteobagrus vachelli Richardson)幼鱼体重(4.34±0.13)g的临界游泳速度(Ucrit),然后分别以临界游泳速度的不同百分比(20、40、60、80、100%Ucrit)将实验鱼分为5个速度处理组,另外设置静止对照组和高速力竭对照组。处理组实验鱼在不同游泳速度下分别游泳20min,在此过程中测定并计算运动代谢率(Activity metabolic rate,AMR),随后测定肌肉、血液和肝脏中的乳酸、糖原和葡萄糖含量。结果显示:实验鱼的绝对临界游泳速度为(48.28±1.02)cm/s,相对临界游泳速度为(6.78±0.16)BL/s;随着游泳速度的提高AMR显著增加(Pcrit时肌乳酸和血乳酸含量显著高于80%Ucrit的水平(P0.05);100%Ucrit时肝糖原含量显著低于40%Ucrit的水平(P0.05)。经计算瓦氏黄颡幼鱼到达临界游泳速度时的无氧代谢功率比例仅为11.0%,表明其游泳运动主要以有氧代谢供能;实验鱼的无氧代谢大约在80%Ucrit才开始启动,与其他鱼类比较启动时间较晚,说明其游泳运动对无氧代谢的依赖程度较低。研究提示瓦氏黄颡幼鱼是一种有氧运动能力较强的鱼类,这一能量代谢特征可能与提高其生存适合度有关。       

摄食水平对瓦氏黄颡鱼餐后代谢特征的影响

以新鲜泥鳅(Misgurus anguillicanndotus)肉块为饵料,采用麻醉灌喂的方法,在(25.0±0.5)℃条件下,研究了瓦氏黄颡鱼(Pelteobagrus vachelli)幼鱼[体重(7.03±0.15)g,n=42]不同摄食水平(饵料分别为体重的0%、1%、2%、4%和8%)对餐后代谢反应的影响.结果显示,在不同摄食水平下,瓦氏黄颗鱼摄食代谢均呈现先上升后下降的整体变化趋势;摄食水平由1%增加到8%,实验鱼的SDA耗能、SDA时间和摄食代谢峰值(PMR)分别从3.09 kJ/kg、8 h和56.08 mg O_2/kg·h增加到47.21 kJ/kg、36 h和97.25 mgO_2/kg·h;其中,8%(饱足摄食水平)和4%摄食水平组的代谢率在峰值水平能够持续20 h左右.瓦氏黄颡鱼最大运动代谢率(MMR)为166.5 mg O_2/kg·h,显著大于饱食组PMR(P＜0.05).本研究还表明,随摄食水平上升,瓦氏黄颡鱼通过PMR的增加和SDA时间的延长来满足SDA耗能增加的需求;从摄食4%组和8%组相似的梯形摄食代谢曲线,可以看出瓦氏黄颡鱼在高摄食水平条件(＞4%)下限制了摄食代谢的上升;PMR相对于静止代谢上升倍率较小,暗示其摄食占据的代谢空间较小,进而保留了大量剩余代谢空间用于运动和其他生理活动,这可能与其活跃的觅食活动习性有关.     

溶氧水平对鲫鱼代谢模式的影响

为了探讨水体溶氧水平对鲫幼鱼(Carassius carassius)运动、消化能力及其交互作用的影响,在(25.0±0.5)℃温度条件下,测定了8(饱和溶氧水平)、2和1mg/L溶氧水平下摄食(饱足摄食)和空腹组(空腹2 d)鲫鱼的临界游泳速度(Ucrit)、运动前耗氧率(MO2pre-exercise)、活跃耗氧率(MO2active)和代谢范围(MS)。摄食诱导的耗氧率上升在各溶氧水平下无显著差异。在饱和溶氧水平下,摄食组和空腹组的Ucrit没有显著差异,但在1和2 mg/L条件下,摄食组的Ucrit显著低于空腹组(P<0.05)。在饱和溶氧水平条件下,消化和运动诱导的耗氧率上升在各个游泳水平均能完全叠加,且摄食组鱼类与空腹组鱼类具有相似的MS和Ucrit和更高的MO2active,提示鲫鱼在常氧下为添加代谢模式。随着溶氧水平下降至2和1mg/L,呼吸能力(摄食组的MO2active)对溶氧水平下降较运动耗氧率更为敏感,消化诱导的耗氧率增加只能在较低游泳速度叠加,与空腹组鱼类比较,摄食组鱼类的MS和Ucrit显著下降,MO2active无显著差异,提示低氧下消化和运动对氧气需求竞争的加剧使其代谢模式转化为消化优先。     

两种温度条件下四种鱼类临界游泳速度的比较

以鳜(Siniperca chuatsi)、瓦氏黄颡鱼(Pelteobagrus vachelli)、鲫(Carassius auratus)、鳙(Aristichthys nobilis)4种暖水性鱼类为研究对象,分别在(28±1)℃和(10±1)℃条件下测定它们的临界游泳速度,采用SPSS17.0统计软件进行数据的分析比较。体长相近的鱼类之间比较,鳜的绝对临界游泳速度和相对临界游泳速度均显著性低于鳙(P0.01),瓦氏黄颡鱼的绝对临界游泳速度和相对临界游泳速度均显著性低于鲫(P0.01)。通过比较两种温度条件下同种鱼的临界游泳速度,结果发现4种鱼在这两种温度条件下的临界游泳速度均有极显著性差异(P0.01),在(28±1)℃条件下4种鱼的临界游泳速度极显著性高于(10±1)℃条件下它们的临界游泳速度。     

生境不完全重叠的两种鲤科鱼类耐低氧及运动能力比较

以乌江流域亲缘关系近,但分布并不完全重叠的马口鱼(Opsariichthys bidens)和宽鳍鱲(Zacco platypus)作为实验对象,分别考察这两种实验鱼的低氧耐受及游泳运动能力。将野外采回的实验鱼置于(25±1)℃条件下,分别测定两种鱼的临界氧分压(Pcrit)、水面呼吸(ASR)、失去平衡点(LOE)以及在不同溶氧水平(8.0、4.0和2.0 mg/L)下的临界游泳速度(Ucrit)和活跃耗氧率(MO2active)。研究发现:马口鱼的Pcrit(2.44±0.20)mg/L显著高于宽鳍鱲(1.86±0.10)mg/L(P=0.031)。但马口鱼的50%ASR(1.23±0.16)mg/L显著低于宽鳍鱲(1.97±0.11)mg/L(P=0.023);马口鱼的50%LOE(0.84±0.01)mg/L同样显著低于宽鳍鱲(0.97±0.02)mg/L(P=0.004)。宽鳍鱲在8.0和4.0 mg/L下的游泳能力显著高于马口鱼,然而马口鱼和宽鳍鱲的Ucrit均随测定溶氧水平的下降而显著降低(P0.01);宽鳍鱲和马口鱼的运动耗氧率均随水流速度的增加而呈现指数增加,但随测定溶氧水平的降低运动耗氧曲线变得相对平缓,尤其是在溶氧为4.0 mg/L时马口鱼的运动耗氧曲线与宽鳍鱲相比越发平缓;两种实验鱼的MO2active随溶氧水平下降的变化趋势与Ucrit相似(P0.001)。结果表明:两种野外生存的实验鱼不仅在低氧耐受能力方面存在显著差异,而且两者的游泳运动能力也有不同表现,这很有可能与其遗传特征、生存环境及生态习性相关。     

饲料脂肪水平对瓦氏黄颡鱼生长及脂蛋白脂酶基因表达的影响

研究采用脂肪水平分别为4.7%、7.9%、10.9%、15.4%、18.9%的五种等氮配合饲料饲喂瓦氏黄颡鱼早期幼鱼,进行了为期30d的生长实验,探讨了瓦氏黄颡鱼早期幼鱼的脂肪需求。并克隆了瓦氏黄颡鱼脂蛋白脂酶(LPL)cDNA序列片段,采用实时荧光定量PCR研究了饲料脂肪水平对肝脏LPL基因表达水平的影响。结果表明,饲料脂肪水平从4.7%增加到10.9%显著促进了瓦氏黄颡鱼早期幼鱼的生长(P<0.05)。饲料脂肪水平显著影响了实验鱼的鱼体体成分,随着饲料脂肪水平的升高,鱼体干物质和脂肪含量显著增加而蛋白含量显著下降(P<0.05)。高脂诱导了瓦氏黄颡鱼肝脏LPL基因表达,摄食15.4%、18.9%这两组较高脂肪水平的实验鱼肝脏LPLmRNA表达水平显著升高(P<0.05)。根据特定生长率通过折线回归分析得出瓦氏黄颡鱼早期幼鱼最适脂肪水平为11.2%。       

溶氧水平对鳊鱼、中华倒刺鲃幼鱼游泳能力的影响

在(25 1)℃条件下, 以鳊鱼(Parabramis pekinensis)体重(4.70 0.11)g, n=32、中华倒刺鲃(Spinibarbus sinensis)体重(3.26 0.06)g, n=32幼鱼为研究对象, 采用鱼类游泳代谢测定仪在水体溶氧为8、4、2、1 mgO2/L条件下分别测定其临界游泳速度(Ucrit)和游泳代谢率(MO2), 并计算出静止代谢率(MO2rest)、最大游泳代谢率(MO2max)、代谢范围(MS)及单位位移能耗(COT)等相关参数。结果显示, 随着溶氧水平的下降, 鳊鱼、中华倒刺鲃幼鱼的Ucrit均逐渐下降, 除中华倒刺鲃幼鱼的值在4与8 mgO2/L下没有显著性差异外, 其他各组均差异显著(P0.05); 在同一溶氧水平下的中华倒刺鲃Ucrit显著大于鳊鱼(P0.05)。两种鱼的MO2max和MS均随DO的下降而显著下降, 但MO2rest在溶氧水平低于1 mgO2/L才显著下降(P0.05)。研究还发现鳊鱼、中华倒刺鲃幼鱼的MO2在同一游泳速度下随溶氧水平下降而降低, 而在相同溶氧水平下随游泳速度的上升而显著升高(P0.05); COT随游泳速度上升而显著降低(P0.05), 但在高游泳速度下相对稳定, 在同一游泳速度下随着DO的下降有所减小。中华倒刺鲃的COT整体上小于鳊鱼, 且在低游泳速度下差异更大。87.5%(1-8 mgO2/L)溶氧水平的下降导致两种鱼类相似的Ucrit变化(53% vs. 50%), 但溶氧水平由8降到4 mgO2/L时, 鳊鱼32%MO2max的下降导致Ucrit下降13%, 但同样的溶氧水平下降虽然导致中华倒刺鲃的MO2max下降20%, 但由于MO2rest和COT的下降, 其Ucrit并没有显著的变化。实验结果表明: 不同溶氧水平对不同鱼种游泳能力的影响存在差异, 这种差异与其代谢对策密切相关。       

黄颡鱼仔、稚、幼鱼耗氧率及氨氮排泄率的初步研究

本文测定了不同温度(20、24、28、32℃)下黄颡鱼仔、稚、幼鱼的耗氧率和氨氮排泄率。结果表明,黄颡鱼的耗氧率、氨氮排泄率随体质量增大而降低,随温度升高而增大;体质量、温度与耗氧率和氨氮排泄率的关系可用R_O=0.0224T^0.6428·e^0.1284W、R_N=0.2654T^0.4326·e^0.1417W表示。     

速度增量及持续时间对瓦氏黄颡鱼幼鱼临界游泳速度的影响

为了考查速度增量(△v)和持续时间(△t)2个参数变化对鱼类临界游泳速度(critical swimming speed,Ucrit)的影响,于25℃条件下,首先以15%临界游泳速度作为△v,设置不同的持续时间(△t:5,10,15,30,60min);再以20min作为△t,设置不同的速度增量(△v:5%,10%,15%,20%,30%Ucrit),测定瓦氏黄颡鱼(Pelteobag vachelli)幼鱼的临界游泳速度。结果表明:随△t的增加Ucrit整体呈下降趋势,△t由5min增加至60min,绝对游泳速度(absolute swimming speed,Ua)由(47.4±0.7)cm.s-1下降至(39.1±1.5)cm.s-1(P<0.05),除15和30min无显著差异外,其余各组间均存在显著差异(P<0.05);而△v由5%提高至10%Ucrit,Ua由(44.1±0.6)cm.s-1显著增加至(47.0±0.4)cm.s-1(P<0.05),15%和20%Ucrit的Ua分别为(45.2±0.2)cm.s-1和(46.3±0.8)cm.s-1,与10%Ucrit组之间均无显著差异,但△v增...     

The effects of temperature on metabolic interaction between digestion and locomotion in juveniles of three cyprinid fish (Carassius auratus, Cyprinus carpio and Spinibarbus sinensis)

To test whether the effects of temperature on the metabolic mode changed among different fish species, we investigated the specific dynamic action (SDA) and swimming performance of fasting and fed fish at 15 and 25°C in three juvenile Cyprinidae fish species: goldfish (Carassius auratus), common carp (Cyprinus carpio) and qingbo (Spinibarbus sinensis). Both taxon and temperature had significant effects on the resting oxygen consumption rate (M˙O(rest)), SDA and swimming performance (p<0.05). In addition, the effect of temperature differed significantly among the different species (interaction effect, p<0.05). Under the low temperature condition, digestion had no effect on either critical swimming speed (U(crit)) or the active MO(2) (MO(active)) for all fish species (additive metabolic mode). When the temperature was increased from 15 to 25°C, the metabolic scope (MS) for digestion increased approximately 182, 49 and 17%, and the MS for locomotion increased approximately 129, 58 and 138% in goldfish, common carp and qingbo, respectively. The total metabolic demands for both digestion and locomotion (i.e., the sum of digestive MS and locomotive MS) increased approximately 143, 56 and 112% in goldfish, common carp and qingbo, respectively. The total MS for both digestion and locomotion (the difference between MO(active) in fed fish and MO(rest) in fasting fish) increased approximately 106, 58 and 78% in goldfish, common carp and qingbo, respectively. Thus, the MS for locomotion in fed goldfish decreased due to the large increase in digestive function at the high temperature, and the U(crit) of fed goldfish decreased by 11% compared to that of fasting fish (p<0.05) (digestion-priory metabolic mode). The metabolic mode of qingbo changed to locomotion-priority mode, as illustrated by the large increase in locomotive MS in response to the increase in temperature. In the common carp, temperature had no effect on metabolic mode as illustrated by the parallel increases in cardio-respiratory capacity and metabolic capacity of digestive and locomotive organs. A discussion on the changes in metabolic mode in response to temperature and its possible relationship with the metabolic characteristics of a given fish species was also documented in this paper.     

Behaviour of rainbow trout Oncorhynchus mykiss presented with a choice of normoxia and stepwise progressive hypoxia

The objective of this study was to identify behavioural adjustments leading to avoidance of hypoxia. Using the oxygen-sensitive species rainbow trout Oncorhynchus mykiss as a model, individual fish were recorded while moving freely between two sides of a test arena: one with normoxia and one with stepwise progressive hypoxia [80-30% dissolved oxygen (DO) air saturation]. The results demonstrated a gradual decrease in the total time spent in hypoxia starting at 80% DO air saturation. At this DO level, the avoidance of hypoxia could not be attributed to changes in spontaneous swimming speed, neither in normoxia nor in hypoxia. Reducing the DO level to 60% air saturation resulted in decreased spontaneous swimming speed in normoxia, yet the number of trips to the hypoxic side of the test arena remained unchanged. Moreover, data revealed increased average residence time per trip in normoxia at DO levels ≤60% air saturation and decreased average residence time per trip in hypoxia at DO levels ≤50% air saturation. Finally, the spontaneous swimming speed in hypoxia increased at DO levels ≤40% air saturation and the number of trips to hypoxia decreased at the 30% DO air saturation level. Thus, avoidance of the deepest hypoxia was connected with a reduced number of trips to hypoxia as well as decreased and increased spontaneous swimming speed in normoxia and hypoxia, respectively. Collectively, the data support the conclusions that the mechanistic basis for avoidance of hypoxia may (1) not involve changes in swimming speed during mild hypoxia and (2) depend on the severity of hypoxia.     

Postprandial intestinal blood flow, metabolic rates, and exercise in Chinook salmon (Oncorhynchus tshawytscha)

Following a relatively large meal (2% body mass of dry pellets), intestinal blood flow in chinook salmon (Oncorhynchus tshawytscha) increased significantly, up to 81%, between 14 and 29 h postprandially. Also, 15 h postprandially, oxygen consumption (M(2)) was elevated by 128% compared with a measurement of routine M(2) made after 1 wk of fasting. The postprandial increase in MO(2) (the heat increment) was 33 micromol O(2) min(-1) kg(-1). Because intestinal blood flow is known to decrease during swimming activity in fish, we therefore tested the hypothesis that swimming fish would have to make a trade-off between maximum swimming activity and digestive activity by comparing the swimming performance and metabolic rates of fed and fasted chinook salmon. As expected, MO(2) increased exponentially with swimming velocity in both fed and fasted fish. Moreover, the heat increment was irreducible during swimming, such that MO(2) remained approximately 39 micromol O(2) min(-1) kg(-1) higher in fed fish than in fasted fish at all comparable swimming speeds. However, maximum M dot o2 was unaffected by feeding and was identical in both fed and fasted fish (approximately 250 micromol O(2) min(-1) kg(-1)), and, as a result, the critical swimming speed (U(crit)) was 9% lower in the fed fish. Three days after the fish were fed and digestion was completed, MO(2) and U(crit) were not significantly different from those measured in fasted fish. The ability of salmonids to maintain feeding metabolism during prolonged swimming performance is discussed, and it is suggested that reduced swimming performance may be due to postprandial sparing of intestinal blood to support digestion, thereby limiting the allocation of blood flow to locomotory muscles.     

The effect of exhaustive chasing training and detraining on swimming performance in juvenile darkbarbel catfish (<Emphasis Type="Italic">Peltebagrus vachelli</Emphasis>)

To investigate the effects of exhaustive chasing training and detraining on the swimming performance of juvenile darkbarbel catfish (Peltebagrus vachelli Richardson), we performed exhaustive chasing training daily for 14 days and subsequently detrained fish for 7 days. Chasing training resulted in significant increases in critical swimming speed (U _crit), post-chasing peak oxygen consumption rate (VO_{2 peak}), and heart and gill indexes compared with non-trained controls. Both resting oxygen consumption (VO_{2 rest}) and excess post-chasing VO₂ (EPOC) were unaffected by exhaustive chasing training. Fish that underwent chasing training had lower levels of whole-body lipid content and reduced food intake and growth compared with non-trained control fish; however, condition factor was not affected by chasing training. Seven days of detraining reversed the effects of exhaustive chasing training. Overall, these data suggested that short-term exhaustive chasing training improves aerobic swimming capacity in darkbarbel catfish, but the training effects are reversible over a short period of time.     

Fasting goldfish, Carassius auratus, and common carp, Cyprinus carpio, use different metabolic strategies when swimming

Fish need to balance their energy use between digestion and other activities, and different metabolic compromises can be pursued. We examined the effects of fasting (7days) on metabolic strategies in goldfish and common carp at different swimming levels. Fasting had no significant effect on swimming performance (U(crit)) of either species. Feeding and swimming profoundly elevated total ammonia (T(amm)) excretion in both species. In fed goldfish, this resulted in increased ammonia quotients (AQ), and additionally plasma and tissue ammonia levels increased with swimming reflecting the importance of protein contribution for aerobic metabolism. In carp, AQ did not change since oxygen consumption (MO(2)) and T(amm) excretion followed the same trend. Plasma ammonia did not increase with swimming suggesting a balance between production and excretion rate except for fasted carp at U(crit). While both species relied on anaerobic metabolism during exhaustive swimming, carp also showed increased lactate levels during routine swimming. Fasting almost completely depleted glycogen stores in carp, but not in goldfish. Both species used liver protein for basal metabolism during fasting and muscle lipid during swimming. In goldfish, feeding metabolism was sacrificed to support swimming metabolism with similar MO(2) and U(crit) between fasted and fed fish, whereas in common carp feeding increased MO(2) at U(crit) to sustain feeding and swimming independently.     

饲料中糖/脂肪比例对瓦氏黄颡鱼生长、饲料利用、血糖水平和肝脏糖酵解酶活力的影响

以初始体重(4.20±0.02)g的瓦氏黄颡鱼(Pelteobagrus vachelli)幼鱼为实验对象,在流水系统中进行为期8周的摄食生长实验,探讨饲料中糖与脂肪比例(CHO∶L)对其生长、饲料利用、血糖水平和糖酵解酶活力的影响。饲料等氮(粗蛋白40%)等能(19 MJ/g),CHO∶L梯度为0.75—6.53。每种饲料随机投喂3桶鱼,每桶(50 L)放养40尾鱼。实验结果表明随着CHO∶L升高,瓦氏黄颡鱼特定生长率(SGR)先升高后降低,当CHO∶L为3.55时,SGR达最大,显著高于CHO∶L为0.75和6.53时的值(P<0.05)。饲料效率(FE)和蛋白效率(PER)在CHO∶L为1.30—3.55区间内都没有显著差异,但当CHO∶L为0.75或6.53时,FE和PER的值都显著降低(P<0.05)。脏体比(VSI)、肝体比(HSI)在各处理组间无显差异(P>0.05)。随CHO∶L的增加,全鱼粗蛋白含量先增加后降低,且在CHO:L为3.55时达到最大值,且显著高于CHO:L为0.75时的值(P<0.05)。而全鱼粗脂肪含量随CHO∶L增加而显著减少(P<0.05)。血糖和血浆总胆固醇水平在各处理组间无显著差异(P>0.05),而血浆甘油三酯水平随CHO∶L的增加而显著增加(P<0.05)。随CHO∶L的增加,瓦氏黄颡鱼肝脏葡萄糖激酶(GK)活力先增加后降低,且在CHO∶L为3.55时活力最大,显著高于CHO∶L为0.75时的值(P<0.05)。肝脏己糖激酶(HK)、丙酮酸激酶(PK)和磷酸果糖激酶(PFK-1)活力在各处理组间没有显著差异(P>0.05)。用二次多项回归模型拟合特定生长率和CHO∶L的关系,得到饲料最适CHO∶L为4.06。