如何解决养殖鱼类的不良生理反应

鱼类为水栖生活的脊椎动物,有着特殊的生理学特性,因水中环境和陆地环境有着巨大的差别。鱼对周围变化所产生的刺激,会使鱼产生相应生理性反应,往往一些生理反应是不良的,使鱼的生理机能产生相应的改变。这种因外界环境的突变而改变鱼内环境的生理机能,使鱼类的正常生理机能受到破坏,危害鱼类的生长繁殖。在鱼类养殖上应给予关注,加以研究,寻求相应的解决方法。一、鱼类对缺氧的生理反应,造成缺氧的原因和解决的方法缺氧是鱼类养殖中常遇到一个敏感而普遍的问题。鱼对缺氧的反应是呼吸加快,心率减慢,心输出量增加。鱼对缺氧的行为反应是浮上水面吞食空气。一般称为“浮头”,鱼对缺氧的程度可以从发生浮头的时间加以判断。如果浮头出现在黎明前后,遇人下沉,可以确定为轻度缺氧。一般情况下在日出后,水生植物光合作用释放氧气的逐渐增强,缺氧现象会很     

环境胁迫对鱼类生理机能的影响

环境胁迫(Environmental stress)指鱼类所处的外界环境对其生存状态产生的压力,胁迫能打破鱼类与环境之间的平衡与协调,引发鱼体正常生理机能出现紊乱。鱼类是水生低等变温脊椎动物,容易受外界环境的影响。通过环境胁迫对鱼类生理机能影响的过程与机制的研究,以期为集约化健康养殖技术的建立提供参考依据。     

非寄生性鱼病的防治

不良水质的影响一、泛池泛池，又叫翻塘或窒息，是由于水中缺氧而引起。鱼类不同种类、不同年龄及在不同季节对氧的要求都各不相同。当水中溶氧低于鱼类正常生理所需最低限度时，就会引起鱼类窒息死亡。通常情况下，淡水鱼类养殖水体中的溶氧不应低于1．0mg／L。（一）泛池的原     

环境内分泌干扰物对鱼类影响的研究进展

水环境中的内分泌干扰物可导致鱼类性别特征丧失和后代不能繁殖,损伤神经、免疫和内分泌系统,引起鱼类种群生存力和资源量下降。介绍了环境内分泌干扰物的概念、种类、作用机制和危害特征,着重阐述了其对鱼类生理生化的影响,讨论了环境内分泌干扰物的降解与研究前景。     

浅谈水中溶解氧与养鱼的关系

水中溶解氧是鱼类赖以生存最重要的生态条件之一,如果水中溶氧量降到一定限度,就会给鱼类生活史的任何一个时期带来不良的影响,推迟鱼类的生长发育,降低抗逆能力,并易被感染鱼病。氧量继续下降就可造成鱼类的大批死亡,这在我省的养鱼生产实践中已屡见不鲜。本文简述了水中溶解氧与养殖鱼类的繁殖、生长、越冬等方面各自相关的关系,并提出了增氧技术及措施。 一、缺氧对鱼类的影响 (一)缺氧对鱼类人工繁     

环境胁迫对鱼类血液影响的研究进展

血液作为反映鱼体生理和健康状况的重要指标,与其生活环境质量直接相关。在养殖生产过程中,鱼类面临着水质因子刺激、营养缺乏等所造成的各种类型环境胁迫,这在鱼类血液变化有所体现。本文对环境胁迫影响下鱼体血液生理指标、生化指标及激素水平的变化特点和相应规律进行了综述,同时认为环境胁迫下鱼体血液相关指标改变是造成体内免疫能力的下降的重要因素。通过施用抗应激药物如中草药等能够增强鱼体免疫力,且在一定程度上可缓解环境胁迫所产生的危害,不过提高在鱼类养殖生产中对环境胁迫危害的认识才是关键。     

鱼用麻醉剂的研究进展

在研究鱼类的生理、疾病或运输时，常需要捕捞鱼类，使其离开所生活的水环境，进行检查、采血、采卵、采精进行人工繁殖等手术。在这些操作过程中，常因捕捞时鱼的挣扎及鱼的应激性反应，造成缺氧或皮肤损伤，导致水霉感染等疾病的发生而引起鱼类死亡。为减少这些危害，常需要对鱼进行麻醉。     

盐度对鱼类的影响

综述了盐度对鱼类存活、生长、消化酶活性、血液生理指标、鳃ATPase活性、鳃丝泌氯细胞结构、激素和肌肉品质等的影响.总结盐度对鱼类生理影响的规律,可为今后鱼类健康养殖和耐盐品系开发提供科学依据.     

鱼类肠道正常菌群研究进展

鱼类肠道正常菌群是肠道的正常组成部分;是肠道微生物与宿主以及所处的水生环境形成的相互依赖、相互制约的微生态系;对营养物质的消化吸收、免疫反应以及器官的发育等方面具有其他因素不可替代的作用,并且影响到鱼类的生长、发育、生理和病理。笔者拟就鱼类肠道菌群的形成、结     

噪声对鱼类影响研究现状与展望

本文对国内外学者就噪声对鱼类听力、信息掩蔽、生理和行为等多方面的研究成果进行了总结，为噪声对鱼类的影响提供较为系统的信息资料。噪声对鱼类行为和鱼类听力、信息掩蔽、其他生理等多方面都会产生不利影响。噪声刺激会显著性增加鱼类游泳速度，减少觅食量，降低产卵成功率；导致鱼类的听力受损；阻碍鱼类之间信息交流，对鱼类寻求配偶产生不利影响，干扰鱼类回声定位；促使鱼体内生理激素、生理应激指标发生不适变化。强烈的噪声刺激会损伤鱼体的器官。目前的研究在实验声场场景、声波粒子运动、实验设置形式和试验周期监测等方面存在一定的不足，多数实验设计都无法模拟真实的声场场景；测量声音的质点运动分量方面鲜有研究；噪声暴露实验设置形式单一且很少进行周期性监测。针对当前的研究缺陷，建议从以下方面改进研究：（1）模拟真实声场场景；（2）探测声波粒子运动对鱼类的影响；（3）开展噪声暴露时间和播放形式方面的研究并进行周期性监测。     

Ichthyoplankton distribution and abundance in relation to nearshore dissolved oxygen levels and other environmental variables within the Northern California Current System

Nearshore hypoxia along the coast of Oregon and Washington is a seasonal phenomenon that has generated concern among scientists studying this temperate upwelling ecosystem. These waters are affected by coastal upwelling‐induced hypoxia mainly during late summer and fall, but the effects of low oxygen levels on fish and invertebrate communities, particularly during the early‐life history stages, are poorly known. We investigated the effects of hypoxia and other variables on the species composition, density, vertical and horizontal distribution of fish larvae along the Oregon and Washington coasts during the summers of 2008, 2009 and 2010. Bottom‐dissolved oxygen (DO) values ranged from 0.49 to 4.79 mL L^?1, but the overall water column DO values were only moderately hypoxic during the 3 yr of sampling compared with recent extreme years. In this study, DO was found to be an environmental parameter affecting the species composition, but other variables such as season, year and depth of capture were also important. Although the overall density of fish larvae increased with increasing bottom‐DO values, the effect on individual species density was limited. Slender sole (Lyopsetta exilis) and sand sole (Psettichthys melanostictus) were the only species to have a weak trend of density with DO, but both showed negative relationships and neither relationship was significant. Our results indicate that larval fish spatial distribution was only moderately affected within the range of observed oxygen values, but low DO may be an important factor under intense hypoxic conditions.     

Physiological and behavioural responses to hypoxia in an invasive freshwater fish species and a native competitor

The spread of invasive species is one of the major environmental concerns which can have negative effects on biodiversity. While several life history traits have been identified as being important for increasing the invasiveness of introduced species, the physiological factors that allow certain species to become successful invaders remain poorly understood. It has been speculated that good invaders are thriving in disturbed environments. In unfavourable conditions, as during hypoxic events, invasive species might be better adapted in their physiological and behavioural responses towards this stressor. We compared physiological and behavioural traits between two freshwater fish species: the European bullhead (Cottus gobio), an invasive fish species in Scotland, and its native competitor the stone loach (Barbatula barbatula) over different dissolved oxygen concentrations (DO). Contrary to expectations, bullhead displayed a reduced hypoxia tolerance as compared to stone loach, indicated by a higher threshold (P_crit) for the maintenance of standard metabolism. Avoidance behaviour during progressive hypoxia was similar between bullhead and stone loach. When given a choice between an open normoxic zone and a shelter located in hypoxia, both species spent most of their time hiding under the shelter in hypoxic conditions (bullhead: 100%; stone loach: 93.93%–99.73%), although stone loach showed brief excursions into normoxic conditions under 25% DO level. These results suggest that stone loach might be more resistant to hypoxia as compared to bullhead, and thus that increased hypoxia tolerance is likely not a trait by which bullhead have been able to expand their range within the United Kingdom.     

Adrenergic Regulation of Lipid Mobilization in Fishes; a Possible Role in Hypoxia Survival

Lipids are for fish the major energy source. The nutritional conditions of most species vary throughout the year considerably. Thus storage and mobilization of lipids have to be tightly controlled, yet little is known about its control. Though several hormones are known to have a lipolytic effect, short term regulation of lipolysis is known for catecholamines only. Catecholamines are usually released under stress conditions, including hypoxia. In mammals these hormones have a strong lipolytic action, causing high plasma fatty acids levels during hypoxia. In contrast to mammals, several fish species show a decrease of plasma FFA-levels during hypoxia and anoxia. However, some studies gave contrasting results when catecholamines were administrated to different fish species. The reason for this may be due to opposing effects of catecholamines on lipolysis in different tissues. From catecholamine administration experiments in cannulated carp there is evidence that norepinephrine inhibits lipolysis via β₁- and β₃- adrenoceptors while β₂-adrenoceptors are involved in stimulation of lipolysis. Thus the opposite responses of different β-adrenoceptors may explain the conflicting in-vivo results obtained with fish. In vitro studies with adipocytes from different fish species confirm that activation of β-adrenoceptors suppresses lipolysis, while the opposite occurs in hepatocytes. Inhibiting β₁- and β₃- adrenoceptors in adipocytes were shown to be involved. Under hypoxia β-oxidation is inhibited, resulting in accumulation of fatty acids together with intermediates of the β-oxidation. This process may cause severe cellular damage in mammalian tissues, which ‘apparently’ does not occur in fishes. Fishes encounter (environmental) hypoxia on a regular basis, while for mammals hypoxia/anoxia is a pathological phenomenon. Hence the suppression of lipolysis in fishes under hypoxia (by β₁- and β₃- adrenoceptors) may be considered as a survival mechanism lost in higher vertebrates.     

The effects of acute and chronic hypoxia on cortisol,glucose and lactate concentrations in different populations of three-spined stickleback

The response of individuals from three different populations of three-spined sticklebacks to acute and chronic periods of hypoxia (4.4 kPa DO, 2.2 mg l⁻¹) was tested using measures of whole-body cortisol, glucose and lactate. Although there was no evidence of a neuroendocrine stress response to acute hypoxia, fish from the population least likely to experience hypoxia in their native habitat had the largest response to low oxygen, with significant evidence of anaerobic glycolysis after 2 h of hypoxia. However, there was no measurable effect of a more prolonged period (7 days) of hypoxia on any of the fish in this study, suggesting that they acclimated to this low level of oxygen over time. Between-population differences in the analytes tested were observed in the control fish of the acute hypoxia trial, which had been in the laboratory for 16 days. These differences were not apparent among the control fish in the chronic exposure groups that had been held in the laboratory for 23 days, suggesting that these site-specific trends in physiological status were acclimatory. Overall, the results of this study suggest that local environmental conditions may shape sticklebacks’ general physiological profile as well as influencing their response to hypoxia.     

Revisiting redox-active antioxidant defenses in response to hypoxic challenge in both hypoxia-tolerant and hypoxia-sensitive fish species

It is not known whether changes in antioxidant levels always occur in fish in response to the oxidative stress that usually accompanies a hypoxic challenge. The studies of antioxidant responses to hypoxia in fish have mostly focused on very anoxia-tolerant species and indicate that there is an enhancement of antioxidant defenses. Here we present new data on redox-active antioxidants from three species, which range in their tolerance to hypoxia: the epaulette shark, threespine stickleback, and rainbow trout, together with a compilation of results from other studies that have measured oxidative stress parameters in hypoxia-exposed fish. The results suggest that in general, fish do not show an increase in redox-active antioxidant defense in response to oxidative stress associated with hypoxia. Rather, the changes in antioxidant defenses during hypoxia are very much species- and tissue-specific and are not linked to the level of hypoxia tolerance of the fish species.     

Temperature and dissolved oxygen influence growth and digestive enzyme activities of yellowtail kingfish Seriola lalandi (Valenciennes, 1833)

A 5 week experiment was carried out with juvenile yellowtail kingfish Seriola lalandi to investigate the interactive effects of water temperature (21, 24, or 27°C) and dissolved oxygen regime (normoxic vs. hypoxic) on the growth rate, feed intake and digestive enzyme activity of this species. Specific growth rate (SGR) was highest at 24°C, regardless of oxygen regime, but the SGRs of the fish exposed to hypoxia at 21, 24 and 27°C were 13%, 20% and 17% lower, respectively, than the SGRs recorded for the fish reared under normoxic conditions. The digestive enzyme activities (i.e. trypsin, lipase and α‐amylase) were influenced by temperature but did not appear to be affected by dissolved oxygen concentration. Information about the effects of water temperature and dissolved oxygen on feeding, growth and digestive capacity of juvenile yellowtail kingfish could contribute to improving feed management decisions for production of this fish species under different environmental conditions.     

鱼类环境耐受性与抗逆性育种研究进展

随着高密度集约化水产养殖业的发展，溶解氧、水温和氨氮等水环境因子胁迫已成为制约渔业高质量发展的限制性因素，抗逆水产新品种的培育成为重要的解决途径之一。本文综述了鱼类对温度、低氧、氨氮、亚硝态氮、盐碱胁迫的响应机制，以及环境耐受性鱼类新品种的育种现状，提出充分利用第一次全国水产养殖种质资源系统调查结果发掘优异种质资源，建立高通量表型和基因型精准鉴定技术，深入解析鱼类响应环境因子胁迫的机制，利用分子标记辅助育种、全基因组选择育种、基因编辑育种和分子设计育种等现代分子育种技术进行高效精准抗逆新品种的培育，为鱼类抗逆性新品种培育提供参考。     

Environmental enrichment for fish in captive environments: effects of physical structures and substrates

Structural environmental enrichment, that is, a deliberate addition of physical complexity to the rearing environment, is sometimes utilized to reduce the expression of the undesirable traits that fish develop in captivity. Increasing demands and regulations regarding usage of enrichment to promote fish welfare also make investigations on the effects of enrichment important. Here, we sythesize the current state‐of‐the‐art knowledge about the effects of structural environmental enrichment for fish in captive environments. We find that enrichment can affect several aspects of the biology of captive fish, for example, aggression, stress, energy expenditure, injury and disease susceptibility. Importantly, these effects are often varying in direction and magnitude, and it is clear that just addition of structure is not a solution to all problems in fish rearing. Each species and life stage needs special consideration with respect to its natural history and preferences. A multitude of different enrichment types has been investigated and many studies investigate several enrichment components at the same time, making comparisons among studies difficult. To the present date, the majority of efforts have been directed to investigate salmonid fish in stock‐fish hatcheries and cichlids from a basic research perspective. Some contexts are under‐studied with respect to environmental enrichment, for instance effects on results in basic research and welfare effects in display aquaria. There are many research opportunities left within this field. However, future studies could utilize experimental designs which make it possible to discriminate between effects of different environmental manipulations to a higher degree than what has been performed to this date.     

脂肪酸对鱼类免疫系统的影响及调控机制研究进展

替代脂肪源的开发和利用是解决鱼油短缺问题的必然选择。然而,随着替代水平的提高,鱼体常常表现免疫水平和抗病能力降低。鱼油替代的本质为脂肪酸替代,深入研究脂肪酸与鱼类免疫的关系显得尤为重要。本实验综述了脂肪酸对鱼类免疫性能的影响及调控机制。饱和脂肪酸会降低鱼类免疫力,而适量添加n-3长链多不饱和脂肪酸(LC-PUFA)、共轭亚油酸(CLA)或提高n-3/n-6多不饱和脂肪酸(PUFA)的比例有利于鱼体免疫力发挥;饲料中脂肪酸主要通过细胞膜结构、信号传导、类花生四烯酸、细胞因子和类固醇激素等途径对鱼类免疫进行调控。脂肪酸与鱼类的免疫性能具有高度相关性,而调控机制的研究尚有较大空间。未来研究应该侧重于以下几个方面:脂肪酸对免疫相关转录因子的调控机制;鱼类肠道脂肪酸组成改变与菌群结构和免疫性能之间的相关性;环境因子对鱼体脂肪代谢和免疫力的影响;非脂肪酸成分(矿物质、维生素)对鱼类脂肪酸代谢和免疫过程的调控机制。     

Effect of Oxygen Saturation in Water on Reproductive Performances of Pacu Piaractus brachypomus

Broodstock pacu Piaractus brachypomus as well as their eggs during their embryonic development were exposed to either normoxia (5.5–7.5 mg O₂/L) or hypoxia (2.0–4.5 mg O²/L) conditions. The plasma concentrations of 11-ketotestosterone in males and estradiol-17β in females, as well as that of their precursor testosterone (T) were significantly ( P < 0.01) higher in fish maintained under normoxic conditions than in fish exposed to hypoxia. After ovulation and spermiation induced by hormonal treatments, the plasma concentrations of T and 17,20β-dihydroxy-4-pregnen-3-one (17,20βP) significantly ( P 0.05) increased in both sexes under both normoxic and hypoxic conditions. The plasma levels of T and 17,20βP achieved under normoxic conditions were higher than the ones recorded under hypoxia, except for those of 17,20βP in males. Males responded positively to the hormonal treatments, and the concentration of spermatozoa was 10.5 ± 0.8 10⁹/mL under both oxygen conditions. Hypoxia resulted in significantly lower survival of embryos (17.3 ± 28%) in comparison to normoxic conditions (68.5 ± 25%). Moreover, larval deformities were found when exposed to hypoxia (91.6 ± 6%). During embryonic development of this species 4 mg/L of oxygen is tolerated at 26–27 C without negative impact. We conclude that despite the highly adaptable nature of adult pacu to environmental hypoxia, oxygen concentrations below 4 mg/L severely impacted survival of embryos.