首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Silver catfish, Rhamdia quelen (Quoy & Gaimard, 1824), is an endemic species from Latin America that is raised in cultivation ponds, and consequently may be exposed to low oxygen levels. Therefore, the objective of this study was to verify the lethal concentration (CL50?96 h) of dissolved oxygen levels for silver catfish juveniles. In addition, the effects of different dissolved oxygen levels (1.96±0.08, 3.10±0.10, 4.14±0.09, 5.20±0.07 and 6.16±0.03 mg L?1) on growth and metabolic parameters (glycogen, glucose, protein, lactate levels and catalase activity) were also investigated. CL50?96 h was 0.52 mg L?1 (CI 0.42–0.61 mg L?1) or 6.7% oxygen saturation. After exposure of silver catfish to hypoxia for 30 days, there were no changes in biochemical parameters indicating the use of an anaerobic pathway by the fish. However, the dissolved oxygen levels influenced silver catfish juvenile behaviour, survival and growth, and under the experimental conditions 5.2 mg L?1 (or 65.6% oxygen saturation) is the minimum oxygen level recommended for the growth of this species.  相似文献   

3.
4.
ABSTRACT

The objective of this study was to evaluate different salt concentrations in the treatment of Ichthyophthirius multifiliis. Silver catfish, Rhamdia quelen, fingerlings infected with I. multifiliis were submitted to four sodium chloride concentrations (g/L): 0,1,2, and 4 for 23 days. In a second experiment, fingerlings were maintained with 4 g/L salt, but for 45 days. Treatments with 2 and 4 g/L salt significantly increased fingerling survival compared with 0 and 1 g/L, and survival was significantly correlated with salt concentrations. In the second experiment, fish maintained at 4 g/L salt showed a gradual reduction of “white spots” and survival was 100%. Therefore, salt offers an alternative for treatment of silver catfish fingerlings infected with I. multifiliis.  相似文献   

5.
Marbled rabbitfish, Siganus rivulatus, is an economically valuable herbivorous fish and a potential candidate for warmwater aquaculture. This study was carried out to: (1) assess the effect of various oxygen concentrations on survival and behaviour of S. rivulatus fingerlings and (2) investigate the response of S. rivulatus to hypoxia and determine its critical oxygen tension (Pcrit). In the first experiment, groups of rabbitfish (15 fish per group) were maintained for 1 h in waters of various oxygen concentrations. They were then transferred to well‐aerated tanks and observed for 72 h. Survival was recorded, fish behaviour at low oxygen concentrations observed, and LC50 after 1‐h hypoxia and 72‐h recovery evaluated. In the second experiment, a series of stop‐flow respirometry experiments were performed during which dissolved oxygen was allowed to drop to 0.5 mg L?1 and respiration rate recorded at various oxygen concentrations. In the first experiment, all fish survived for 1 h at oxygen concentration of 1.44 mg L?1 and greater, but started dying at oxygen concentrations below 0.65 mg L?1 (16% survival). The LC50 of S. rivulatus fingerlings was 0.6 mg L?1. Results of the second experiment showed that S. rivulatus is an oxyregulator until Pcrit (1.7 mg L?1 O2) is reached, becoming an oxyconformer below this concentration. Findings allow for a better understanding of environmental oxygen tolerances and minimum acceptable oxygen concentration in rabbitfish aquaculture.  相似文献   

6.
The purpose of this study was to verify the effect of dietary Ca2+ on the growth and survival of silver catfish fingerlings (Rhamdia quelen) exposed to different water pH (5.5, 7.5 and 9.0). Silver catfish fingerlings were randomly placed in a thermoregulated water re‐use system with twelve 250 L‐tanks, two 1000 L‐biofilters and a 2000 L‐reservoir with a medium flow of 3.84 L min?1 tank. Stocking density was 0.16 fingerlings L?1. To prepare the treatment diets, the control diet (0.8 g kg?1 Ca2+) was supplemented with CaCO3 to yield experimental diets with 6.4, 9.5 and 23.9 g kg?1 Ca2+. There were three replicates/treatments. Survival was more than 93.9% in all treatments. Exposure of silver catfish fingerlings to alkaline or acid water reduced growth, and this effect was not ameliorated by dietary Ca2+ supplementation. Moreover, when fingerlings were maintained in water with pH 7.5, the best dietary Ca2+ range for silver catfish fingerling growth was 0.8–6.4 g kg?1.  相似文献   

7.
罗氏沼虾蚤状幼体耗氧速率与窒息点测定   总被引:9,自引:0,他引:9  
王爱敏 《齐鲁渔业》1997,14(2):37-39
以罗氏沼虾蚤状幼体V与IX期为试验对象,在水温28.5±0.2℃条件下测定其瞬时耗氧速率;并将瞬时耗氧速率与时间、溶氧量作相关分析。结果:耗氧速率随时间延长、溶氧量下降而递减;蚤状幼体V与IX期昏迷点分别为2.18mg/L,1.34mg/L;窒息点分别为1.85mg/L,1.26mg/L。  相似文献   

8.
温度对墨西哥湾扇贝幼虫和稚贝生长与存活的影响   总被引:9,自引:2,他引:9  
为研究墨西哥湾扇贝人工育苗的适宜温度,2000年4月和2001年4月在浙江省玉环县抛西水产育苗场,通过设置不同温度梯度,研究了海水温度对墨西哥湾扇贝浮游幼虫和稚贝生长与存活的影响。结果表明:墨西哥湾扇贝浮游幼虫的适宜温度为20-33℃,最佳生长温度为25-30℃。稚贝的适宜温度为15-33℃,最适生长温度为25-30℃。  相似文献   

9.
为研究沿海滩涂养殖水体中溶解氧的变化规律及其影响因素,2006~2007年对江苏射阳盐场滩涂养殖水体中溶解氧的变化进行了调查研究,并与养殖环境中其它因子的关系作了研究分析。结果表明,养殖区溶解氧的含量显著低于非养殖区,夏、秋季溶解氧的含量显著低于春、冬季。相关分析表明,水体中溶解氧的含量与水体中pH值、盐度、叶绿素a、硝酸氮呈显著的正相关,与水体中温度、铵氮、亚硝酸氮、无机磷,底质中硫化物、无机磷都呈显著的负相关。研究结果证实了滩涂大规模的养殖生产是影响水体中溶解氧含量的一个重要因素。  相似文献   

10.
Plant sources are receiving special attention as feedstuffs in aquafeeds because of fish meal and oil shortage. However, studies about the effects of dietary fibre in fish are scarce. The inclusion of plant ingredients containing different levels of dietary fibre – broken rice (BR), ground corn (GC), wheat bran (WB), citrus pulp (CP) and soybean hulls (SH) were evaluated for the omnivores jundiá catfish and Nile tilapia. Tilapia is a typical omnivore with long intestines, whereas jundiá has short intestines and no pyloric ceca. Fibrous sources (CP, WB and SH) were less digestible for both species than the starchy ones (BR and GC). However, jundiá presented less ability to utilize the starch and protein from plant sources than tilapia. Growth of tilapia followed plant sources digestibility but no significant differences were detected for jundiá, probably because of its slower growth rate. Muscle layer was thicker in the distal intestine of jundiá fed CP diet, which possibly indicates an adaptation to propel the large volume of viscous digesta along the intestine. Therefore, despite its lower ability to utilize starchy plant sources, jundiá showed an adaptive capacity to utilize fibrous diets, which is in agreement with its omnivorous feeding habit.  相似文献   

11.
中国对虾瞬时耗氧速率与海水比重及溶氧水平的相关   总被引:12,自引:1,他引:12  
以中国对虾(7.30±0.32g/p,8.12±0.14cm/p)为测试对象,在海水比重d_1=1.0015至d_7=1.0305之间7个梯度组中分别饲养10天,于32±1℃水温条件下测定对虾的瞬时耗氧速率(V.mg/g·h);遂将瞬时耗氧速率与时间、溶氧量(DO,mg/L)和水的比重作相关分析。结果是耗氧速率随时间延长、溶氧下降而递减;当比重在1.0030~1.0185范围内。耗氧速率随比重增加而增大。7个比重组虾的昏迷点为0.61~1.48mg/L,窒息点为0.61~1.06mg/L。  相似文献   

12.
试验旨在分析新型微米纯氧气泡增氧养殖大菱鲆的效果。试验采用微米纯氧气泡增氧和机械增氧2种方式,设置机械增氧组(溶解氧6~9 mg/L)、微米纯氧增氧Ⅰ组(溶解氧6~9 mg/L)和微米纯氧增氧Ⅱ组(溶解氧15~20 mg/L)3个试验组。结果表明,微米纯氧Ⅰ组大菱鲆的体重增长、成活率、肥满度及饵料转化率高于机械增氧组;微米纯氧Ⅱ组各指标低于机械增氧组。7个月的大规模生产试验(800 m2水面,溶解氧6~9 mg/L)表明,采用微米纯氧气泡增氧养殖大菱鲆,各测定指标均显著高于机械增氧,可以加快大菱鲆生长,提高成活率和饵料转化率。  相似文献   

13.
酸碱度和干露对墨西哥湾扇贝幼虫和稚贝的影响   总被引:2,自引:0,他引:2  
为探讨酸碱度和干露对墨西哥湾扇贝不同发育阶段的影响,2000年4月和2001年4月在浙江省玉环县抛西水产育苗场用实验生态的方法研究了酸碱度和干露对墨西哥湾扇贝浮游幼虫和稚贝生长和存活的影响。结果表明:pH值7~8存活率最高,生长最好。稚贝的耐干露能力低下。  相似文献   

14.
ABSTRACT

Vertical water circulation by the paddle wheel aerator was determined by measuring dissolved oxygen profiles in a 3.6-m deep watershed pond during daylight hours, using aerated and non-aerated treatments. The paddle wheel aerator circulated the well-oxygenated surface water to the pond bottom, producing a uniform dissolved oxygen profile in the aerated treatment, while the non-aerated treatment maintained high dissolved oxygen concentrations near the surface with low dissolved oxygen concentrations near the pond bottom. The aerated treatment contained 35.6% less dissolved oxygen than the non-aerated treatment after four hours as a result of operating the aerator during the daytime. The paddle wheel aerator, with a shallow (10 cm) paddle immersion, is effective in vertically circulating water in deeper ponds. However, substantial loss of dissolved oxygen may result from operating the aerator on days with high rates of photosynthesis.  相似文献   

15.
水温和盐度对大菱鲆稚鱼存活的影响   总被引:5,自引:0,他引:5  
采用突然改变温度和盐度的方法,试验不同水温和盐度对大菱鲆稚鱼存活的影响。试验结果表明,水温为15.0~18.0℃、盐度为28~32,大菱鲆稚鱼存活率最高;用曲线回归的方法求出24 h内存活率与温度的关系式,其回归方程为y=-0.5506x2 18.4970x-53.13,依此得到大菱鲆稚鱼的高、低起始致死温度为26.54℃和7.06℃。依同样方法得到24h内存活率与盐度的回归方程为y=-0.4353x2 23.4226x-213.81,高、低起始致死盐度为37.76和16.05。经t检验显著相关(P<0.01)。  相似文献   

16.
不同环境条件对方斑东风螺幼螺生长、存活的影响   总被引:5,自引:3,他引:5  
本文报道了壳高4.13 mm的方斑东风螺幼螺,在不同密度、换水量、投饵率条件下的生长、存活情况.结果表明,在0.6~4.0万个/m2的密度范围内,在小水泥池(0.9 m×0.6 m×0.6 m),日换水量100~400%条件下,密度0.6万个/m2试验组生长最快,28 d平均体重增长24.4 mg/d,体重日均增长率5.9%,存活率最高,28 d平均存活率95.9%,且换水量达到100%以后,换水量的增大,对幼螺的生长和存活率的提高无明显促进作用.认为合适的条件是:密度0.6万粒/m2或略大于0.6万粒/m2,日换水量100~200%,日投饵率6~7%.  相似文献   

17.
Performance traits and body composition of juvenile hybrid striped bass (Morone chrysops × M. saxatilis) in response to hypoxia were evaluated in replicate tanks maintained at constant dissolved oxygen concentrations that averaged 23.0 ± 2.3%, 39.7 ± 3.0% and 105.5 ± 9.5% dissolved oxygen saturation. Fish were fed a commercially formulated feed daily to apparent satiation. Total feed intake and fish growth and yield increased linearly in response to increased dissolved oxygen concentration. Nutrient utilization was reduced significantly only at the greatest level of hypoxia. With the exception of whole body protein content, whole body compositional indices and nutrient retention efficiencies were linearly related to dissolved oxygen concentration. Results demonstrate that as hypoxia becomes more severe, juvenile hybrid striped bass feed intake is reduced, which affects growth and nutrient retention.  相似文献   

18.
19.
为探究三峡库区支流垂向水环境的分布特征及其影响因素,采用2018年2月(高水位期)和7月(汛期)对三峡水库典型一级支流——神农溪回水区水质监测数据,分析和对比了神农溪不同季节的溶解氧和叶绿素a等指标垂向分布特征,讨论了影响其垂向分布的环境因子。结果表明,神农溪高水位期与汛期的溶解氧含量在0~12 m和0~6 m水体分层现象明显,其表层水体的溶解氧饱和度(SDO)分别为104.04%和171.96%,已经达到过度饱和状态(SDO>100%);中层水体溶解氧浓度存在分层现象,底层水体溶解氧浓度较稳定,无分层现象。高水位期与汛期的叶绿素a含量在0~10 m水体分层现象明显,表层水体的叶绿素a浓度整体上表现为中度富营养化(5 μg/L相似文献   

20.
不同投喂率对南方鲇稚鱼生长和存活率的影响   总被引:1,自引:0,他引:1  
以6个水丝蚓投喂水平培育6日龄南方鲇稚鱼,测定了不同投喂率下稚鱼的摄食水平、生长、存活率和残食率。结果表明,鱼苗体长小于5cm时,投喂鱼苗体重60%的饵料鱼苗生长最快,特定生长率高达19.1%;体长大于5cm时,体长增长和体重特定生长率以50%投喂率组较高,但与60%投喂率组的差异不显著。A、B、C、D、E和F组(分别投喂30%、40%、50%、60%、70%和80%稚鱼体重的饵料)的存活率分别为56%、75%、87%、89%、91%和90%。A、B组的残食率较高,分别是30%和19%;E、F组最小,分别是4%和4.5%。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号