鱼类对溶解气体过饱和水体的敏感性分析

大坝泄洪可携带大量空气进入水中,导致下游河道出现溶解气体过饱和,给水生生物特别是鱼类的生存造成威胁。通过自行设计的室内试验装置,研究了影响溶解气体过饱和度的因素及不同鱼类对气体溶解过饱和的敏感性。鱼类暴露在溶解气体过饱和环境中易出现突眼、充血和气泡等气泡病症状。鲢、鳙和鳊在溶解气体含量高的水体中容易患气泡病,草鱼和鲫稍次,基本可以忽略溶解气体过饱和对黄颡鱼和鲶的影响。     

鱼类气泡病的防治方法

气泡病多发生在池塘养殖的鱼苗、鱼种阶段,但随着池塘精养高产面积的不断扩大,成鱼养殖阶段也经常发生。另外,工厂化温流水养殖的罗非鱼和小面积金鱼的养殖中也易患此病。特别是水花下塘不久,气泡病危害最严重,鱼苗越小越敏感,如抢救不及时,可引起鱼苗大批死亡甚至全部死亡,成鱼有时也可造成大的死亡损失。笔者在多年从事鱼类病害防治工作中对气泡病的防治方法进行了探讨,并作如下介绍,以降低该病的发生。1气泡病的产生原因气泡病是由水中某种气体过饱和所引起,具体原因     

健康养殖专栏

鱼类气泡病的防治鱼类“气泡病”多发生在多年养殖、塘底淤泥厚的池塘或池水很肥的池塘。在夏秋季,若池水很肥,浮游植物通过光合作用产生大量氧气,下午通常出现溶氧过饱和现象,较小的鱼体吞食了氧气气泡后就容易得气泡病。冬季结冰后,阻断了水体和大气的气体交换,由池底淤泥、残饵、粪便分解产生的甲烷、氨氮和二氧化碳气体,在水中大量富积,此时可看到水底冒出大量的气泡（气体过饱和）,从而使鱼得气泡病。气泡病的预防：最好每年在秋放前清一次淤,将塘泥挖去１５～２０ｃｍ。在夏秋季每１５天用“底净”２５公斤／亩全池均匀泼洒…     

慢性气泡病发生机理及其衍生后遗症的危害

水温形成的养殖水体上下分层非常普遍且明显.晴天上表水层藻类光合作用产生的氧气,与池底有机物处于缺氧还原环境下脱氮产生的氮气,在上下水层不能进行交流的情况下,经常处于过饱和的现象.生存在这样水体的鱼类,不论是在鱼苗阶段还是成鱼阶段,过饱和游离气体将不可避免地进入其体内,使其患上气泡病.相对于鱼苗气泡病的急性发病症状,患上...     

虹鳟气泡病的危害与对策

虹鳟气泡病的危害与对策气泡病是一种非病原体引起的鱼病。凡水中某种气体过饱和，均可引起鱼患气泡病，主要危害苗种。虹鳟是一种对溶氧量要求较高的鱼类，最适溶氧量９～１２毫克／升。当水中溶氧量降至５毫克／升时，其呼吸即感困难；夏季，虹鳟的溶氧量致死点为３毫克...     

中国对虾气泡病成因机制

中国对虾气泡病成因机制中国科学院海洋研究所虾病专家张乃禹近几年对中国对虾气泡病成因及防治方法进行了研究，张乃禹通过实验，对中国对虾气泡病成因机制研究获得了较理想的结果，他认为，水温突然升高使水中溶解气体过饱和是导致对虾气泡病的必不可少的重要条件，但不...     

鱼类越冬中后期严防气泡病的发生

鱼类越冬池溶解氧含量过低会使鱼窒息死亡,但溶解氧含量过高是造成鱼类气泡病的主要原因;尤其在越冬中、后期池塘水质较肥的池塘,水中浮游植物含量过多,光合作用产氧能力高,使水中的溶解氧达到过饱和。气泡病一般发生在越冬中期和后期,由于前期一般     

鱼苗气泡病的病因与防治

一、病因水中任何一种气体过饱和，都可引起水产动物患气泡病。越幼小的个体越敏感，主要危害鱼苗，如不及时抢救，可引起幼苗大批死亡，甚至全部死光。引起水中某种气体过饱和的原因很多，常见的有：工．浮游植物过多，在强烈阳光照射的中午，水温高，藻类行光合作用旺盛，可引起水中溶氧过饱和。2．施放过多未经发酵的肥料，肥料在池底不断分解，消耗大量氧气，在缺氧情况下，分解放出很多细小的甲烷、硫化氢气泡，鱼苗误将小气泡当浮游生物吞人，引起气泡病。3．有些地下水含氮过饱和，或地下有沼气，也可引起气泡病，且比氧过饱和的危害…     

鱼类气泡病的成因及防治

在我国北方地区,气泡病是池塘养殖鱼类的常见病,鱼苗养殖期、鱼种养殖期、成鱼养殖前期及鱼类越冬后期常有发生,发病后可造成鱼类大批死亡,甚至全军覆没。一、病因由于养殖水体过肥,水体溶解氧过饱和引起。当养殖水体溶解氧过饱和时,过饱和的氧气通过鳃经血液循环进入鱼体,血液     

一例新型气泡病病例分析

鱼类气泡病是由养殖水体中溶解的过饱和气体析出气泡引起鱼苗失去游泳能力或失去消化功能,可致鱼苗大量死亡.通过目检、鱼体解剖、显微镜检、水质检测等方式对一起死鱼案例调查,分析了因高压和机械作用产生空气气泡致鱼死亡原因,提出解决方案,为水产养殖场建场和养殖管理提供参考.     

The tolerance threshold of Chinese sucker to total dissolved gas supersaturation

Total dissolved gas (TDG) supersaturation generated in the river may result in gas bubble disease to Chinese sucker (Myxocyprinus asiaticus Bleeker) and cause their mortality. To assess the effects of TDG supersaturation on Chinese suckers in laboratory, juvenile fish were exposed to different levels of TDG supersaturated water. All of the fish died when the TDG saturation reached and exceeded 125%, but none died at TDG of 120% saturation in 96 h. To evaluate the effects of intermittent exposure of TDG supersaturation, Chinese suckers were exposed to TDG of 130% for a specific duration and then provided a recovery period at 100% saturation. The results showed that some remission is possible for intermittent exposure. Because of the characteristics of natural rivers, experiments exploring the TDG supersaturation detection and avoidance abilities of Chinese suckers were conducted and demonstrated the fish can avoid TDG supersaturation in both the horizontal and vertical directions when higher TDG levels were available. The results indicate the tolerance threshold of juvenile Chinese suckers is a TDG level of 120% saturation.     

Total gas pressure and oxygen and nitrogen saturation in warmwater ponds aerated with airlift pumps

Gas bubble disease and improper inflation of swim bladders in larval striped bass Morone saxatilis have been recently related in laboratory studies to very low levels of gas supersaturation. In other species, kills resulting from gas supersaturation have been reported in natural waters as large as Galveston Bay. We monitored warmwater ponds during spring to determine the extent of naturally occurring gas supersaturation and compared these levels with levels of gas saturation in ponds equipped with airlift pumps. Total gas pressure averaged 110% in the morning at the surface of non-aerated ponds and in the afternoon in ponds with airlift pumps. At other times of the day total gas pressure averaged 106–107% at the surface and bottom, morning and afternoon, in both aerated and non-aerated ponds. No evidence of gas bubble disease was found in 15-day-old striped bass fry cultured for 42 days in either aerated or non-aerated ponds.     

Hatching rate of Chinese sucker (Myxocyprinus asiaticus Bleeker) eggs exposed to total dissolved gas (TDG) supersaturation and the tolerance of juveniles to the interaction of TDG supersaturation and suspended sediment

Flood discharge containing excessive suspended sediments (SS) can result in total dissolved gas (TDG) supersaturation downstream of dams. It has been confirmed that high TDG levels and excessive SS cause serious threats to fish survival. To explore the effects of TDG supersaturation on the hatchability of Chinese sucker (Myxocyprinus asiaticus Bleeker) eggs, eggs were exposed to 100%, 125%, 130% and 135% TDG supersaturated water. The results showed that the hatching rates were 78.25%, 75.35%, 71.30% and 67.50% at the 100%, 125%, 130% and 135% TDG respectively. The hatching rate decreased with increasing TDG levels. Furthermore, acute lethality experiments were carried out to investigate the interaction of TDG supersaturation and SS on Chinese sucker. Half‐year‐old juveniles were exposed to TDG supersaturated water with SS concentrations of 0, 200, 600 and 1,000 mg/L, and the TDG levels were 125%, 130%, 135% and 140% respectively. The fish exhibited abnormal behaviours and signs of gas bubble disease. Mortality increased with increasing TDG levels and SS concentrations. The Chinese suckers only survived for 2.5 hr at 140% TDG and 1,000 mg/L SS. Moreover, an increase in SS in TDG supersaturated water could cause a decrease in the median lethal time (LT₅₀). When the TDG level reached 140%, the LT₅₀ declines significantly at 600 and 1,000 mg/L SS. The interaction of TDG supersaturation and SS was significant at LT₅₀ (F = 22.81, df = 9, p < 0.001). The results indicate that the combined effect of TDG and SS could be great on Chinese sucker.     

三峡工程运行后长江中游溶解气体过饱和演变研究

为了分析三峡工程运行后泄洪对长江中游溶解气体过饱和的影响,本文建立了长江中游溶解氧数学模型,对不同流量下长江中游的溶解氧过饱和演变进行了模拟预测。模拟结果表明,三峡和葛洲坝过坝水流的溶解氧饱和度在40000m3/s～50000m3/s和100000m3/s附近存在两个峰值,长江中游河道天然情况下溶解氧过饱和恢复速度较为缓慢,平均每100km降低5%,洞庭湖水的汇入能显著降低长江干流的溶解氧过饱和度。当三峡出库流量超过40000 m3/s时,其影响范围可达400km以上。本文讨论了溶解气体过饱和的不同指标间的关系,对气体过饱和可能造成的影响以及对长江中游鱼类目前的影响进行了阐述,认为通过三峡水库的调度减小出库高流量次数和历时是减缓下游溶解气体过饱和的有效手段。     

长薄鳅对过饱和总溶解气体的回避特征研究

高坝泄洪过程中,高速水流造成下游水体的总溶解气体(Total Dissolved Gas,TDG)过饱和极易使得水体中的鱼类患上气泡病,进而对下游水体的鱼类生存造成威胁。为了探究长薄鳅(Leptobotia elongate)幼鱼对TDG过饱和水体的探知回避能力,本实验以2月龄的长薄鳅为研究对象,记录其在不同TDG饱和度水体中的反应和趋向。结果表明,在120%TDG过饱和水体中,长薄鳅回避率为-20%,其对该饱和度下的水体表现出了一定的趋向性;TDG饱和度为130%时,长薄鳅回避率为-2%,无明显回避能力;TDG饱和度为140%时,长薄鳅展现出微弱的回避特征,其在清水与过饱和水体之间往复游动,最终回避率为12%;150%TDG过饱和水体中,长薄鳅体现出敏锐的探知能力,1~2 min后开始频繁游动,同时具有一定的回避能力,回避率为34%。长薄鳅的回避率与过饱和水体浓度呈现较强的线性相关关系,水体TDG饱和度越高,实验鱼回避现象越明显。     

The effects of dissolved gas supersaturation on larval striped bass, Morone saxatilis (Walbaum)

Abstract. Gas bubble disease in larval striped bass, Morone saxatilis (Walbaum), was characterized by overinflation of the swimbladder and the formation of intestinal bubbles. This accumulation of gas hindered normal swimming of the fish and in extreme cases resulted in floating fish. As gas accumulated in the gut, the inner mucosal lining was compressed down into a cuboidal epithelium and in more advanced cases nearly the entire digestive tract was reduced to a squamous inner epithelium surrounded by a thin serosa. A significant increase in swimbladder volume was observed at total gas pressures as low as 102.9% and mortality was increased at 105.6-106.0%. The older larvae (30-day-old) were less sensitive to gas supersaturation than 10- to 19-day-old larvae.     

Effects of Oxygen Supplementation on Lake Trout Brood Stock

This study was conducted to determine the effects of oxygen supplementation and nitrogen supersaturation on the fecundity and performance of Lewis Lake strain lake trout, Salvelinus namaycush, brood stock. Performance of brood fish held in water supersaturated with oxygen was compared to that of controls raised at or below 100% saturation for 334 days. Incoming water averaged 78.4% saturation in the morning; the addition of oxygen increased saturation to 104.6%. As a result, average morning nitrogen saturation was reduced from 105.7% to 100.9%. In oxygen-supplemented water, peak daily oxygen saturation averged 129.0% in the afternoon. At this saturation level, average nitrogen gas was reduced to 98.4% saturation. Total gas pressure never exceeded 109.1% with oxygen supplementation; however, nitrogen supersaturation reached 110% in raceways with no oxygen supplementation. Weight gain, feed conversion, egg survival, egg size, and number of eggs per female were not affected by increasing oxygen saturation.     

An explanation for the high resistance of incubating salmonid eggs to atmospheric gas supersaturation of water

Embryonic stages of development within the salmonid egg are more resistant to the effects of atmospheric gas supersaturation, compared with later stages following hatching. We show that the hydrostatic pressure maintained under the capsule (zona radiata) of the egg is sufficient to compensate for a substantial portion of the excess total gas pressure to which the egg may be exposed in supersaturated water. That is, total gas pressure thresholds for gas bubble trauma are raised above those applying to later developmental stages, following hatching, as a result of normal infracapsular pressure.     

Some effects of gas-supersaturated seawater on Spisula solidissima and Argopecten irradians

Two size classes of the surf clam, Spisula solidissima, and the bay scallop, Argopecten irradians, were exposed to different concentrations of gas-supersaturated seawater in a flowing seawater system. Both species tested experienced no mortality when held in the control treatment maintained at 96% oxygen and 109% nitrogen. Mortality, gill tissue damage, gas emboli, membranous tissue blisters, and abnormal secretion of shell material were induced experimentally at elevated levels of gas supersaturation. Results indicate significant mortalities of surf clams and scallops held at 114% O₂ and 195% N₂, and at higher levels of gas concentration. These values suggest a point of reference for the bivalve culturist in identifying potential problems which can be caused by gas-supersaturated seawater.