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71.
为探究三峡水库小江流域常见草食性、浮游生物食性、肉食性和杂食性鱼类肌肉的碳(C)、氮(N)、磷(P)生态化学计量特征,2018年1月(枯水期)和7月(丰水期)在小江流域7个设定断面,采集4种食性的鱼类样品,测定其生长特性指标,分析鱼类肌肉C、N、P生态化学计量特征及相关性。结果表明,鱼类肌肉C、N、P元素含量为34.75%~58.71%、 7.00%~15.45%、0.89%~8.21%,C:N、C:P和N:P为3.62~9.75、16.92~136.95、2.14~35.31,其中磷元素含量变化最大且是导致N:P变化的主要原因。小江流域不同食性鱼类肌肉元素组成差异不明显,其中仅草食性鱼类、浮游生物食性鱼类 的N含量和N:P显著大于肉食性鱼类和杂食性鱼类(P<0.05),其他元素及比例在各食性鱼类之间均无显著性差异(P>0.05);不同采样断面的鱼类肌肉元素含量及比例无显著性差异(P<0.05);相关性分析发现,小江流域鱼类肌肉N和 P含量呈负相关关系(P<0.05),除草食性外,各食性鱼类的N含量均与水体NO-3-N含量呈显著正相关(P<0.05)。研究结果对深入了解大坝干扰下水生态系统食物网营养关系及营养循环格局具有重要意义。  相似文献   
72.
ABSTRACT:   The nucleotide sequences of Japanese flounder Paralichthys olivaceus , major histocompatibility complex (MHC) cDNA, classical MHC class Iα, non-classical MHC class Iβ, MHC class IIα and IIβ, were determined. The domain structures and antigen binding motifs of vertebrate MHC are conserved in the Japanese flounder MHC. A phylogenetic analysis supports the classification of these genes into class I and class II MHC. Classical MHC class Iα was ubiquitously expressed, whereas the non-classical MHC class Iβ was expressed mainly in lymphoid organs, gills, intestine and stomach. The MHC classes IIα and IIβ were also ubiquitously expressed.  相似文献   
73.
Abstract –  This study examined whether habitat use by the African anabantid fish Ctenopoma muriei is consistent with predictions relating to two costs of air breathing (surface travel and aerial predation). We predicted that C. muriei would be most abundant in habitats that minimize potential costs of air breathing. We quantified environmental correlates of C. muriei abundance within a series of wetland lagoons in Uganda and found that C. muriei was more abundant in shallow waters of the deepest lagoon, in vegetated habitats, and at a depth 15–30 cm below the surface. These locations may minimize cost of travel to the surface for aerial respiration, while maintaining a reasonable distance from the surface to avoid detection by aerial predators. In addition, we experimentally tested effectiveness of vegetative cover in reducing mortality of C. muriei by aerial predators (pied kingfishers) using enclosures with and without vegetation cover in a swamp pool. We found that the presence of vegetative cover significantly reduced susceptibility of C. muriei to predation by pied kingfishers when dissolved oxygen in the water was low and air-breathing frequency was potentially high.  相似文献   
74.
Abstract –  Pseudoplatystoma corruscans is distributed widely in the La Plata Basin in Brazil, where it is a very important species because of its high commercial value and ecological role as a voracious predator. This species undertakes long migrations during the dry and rainy seasons to feed and reproduce, respectively. In this study, we analysed seven microsatellite loci to test the hypotheses of the existence of a single panmictic population of P. corruscans in the La Plata Basin. All microsatellites analysed were highly polymorphic with the number of alleles per locus ranging from seven (Pcor28) to 30 (Pcor10). Across all samples, 107 alleles were detected. Thirty alleles were private, i.e., found in only one sample. Highly significant genetic differentiation was observed among samples in three of the four analyses performed: F ST (from 0.03435 to 0.16349, P  < 0.05), Analysis of molecular variance (amova) F ST = 8.25% ( P  < 0.0001) and amova R ST = 9.72% ( P  < 0.0001). A microsatellite multilocus Bayesian assignment test with the programme structure confirmed the division of the fishes into six groups largely concurrent with main branches on a population neighbour-joining tree. The obtained results rejected the panmixia hypothesis. On the other hand, the documented long-distance movements of P. corruscans and the geographical scale of genetic differentiation found in this study indicate a strong tendency for fish of this species to utilise their natal nursery regions for reproduction, which represents the first demonstrated example of homing in a freshwater catfish in South America.  相似文献   
75.
ObjectiveTo verify the efficacy of citral in inducing sedation and anesthesia in silver catfish (Rhamdia quelen) and grass carp (Ctenopharyngodon idella) and to assess the safety of essential oil (EO) of Aloysia citriodora and citral in inducing and maintaining anesthesia in silver catfish.Study designClinical study, randomized, parallel, multi-arm with control group in target species.AnimalsA total of 96 juvenile and 72 adult silver catfish and 80 juvenile grass carp were used.MethodsSilver catfish and grass carp were exposed to different concentrations of citral, 15–675 and 15–600 μL L–1, respectively, during the maximum period of 30 minutes to verify sedation and anesthesia induction and recovery times. In addition, for anesthetic induction, silver catfish were exposed to the EO of A. citriodora and citral at 225 μL L–1 for 3.5 minutes. Then, fish were transferred to an anesthesia maintenance solution at 50 μL L–1 for 10 minutes to assess hematologic and biochemical variables at 60 minutes, 2 and 6 days after treatment.ResultsCitral only induced sedation from 15, 25 and 40 μLL–1 in both species. Anesthesia without mortality was induced in silver catfish at 50–600 μL L–1 and grass carp at 75–450 μL L–1. At 675 and 600 μL L–1, mortality was recorded in silver catfish and grass carp, respectively. The EO of A. citriodora and citral were safe in inducing and maintaining anesthesia in silver catfish, with mean corpuscular hemoglobin concentration being the only variable that varied in relation to time and treatments.Conclusions and clinical relevanceCitral was effective in inducing sedation and anesthesia in both species. In addition, A. citriodora EO and citral were safe in inducing and maintaining anesthesia in silver catfish. Both agents are promising substances for the development of new drugs for fish.  相似文献   
76.
The purpose of the study was to test the hypothesis that the dietary oils with different content of n‐3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) affect plasma lipid level in rats in a different degree. The diets with 6% of fish oil (FO) and Schizochytrium microalga oil (SchO; EPA+DHA content in the diets 9.5 + 12.3 and 2.6 + 29.5% of the sum of total fatty acids, respectively) were used; the diet with 6% of safflower oil (high content of n‐6 PUFA linoleic acid, 65.5%; EPA+DHA content 0.7 + 0.9%) was used as a control. The difference between FO and SchO was established only in the case of plasma triacylglycerol (TAG) level: plasma TAG of the FO‐fed rats did not differ from the control rats (p > 0.05), while SchO decreased (p < 0.05) plasma TAG to 46% of the control. On the other hand, FO and SchO decreased (p < 0.05) total plasma cholesterol (TC) in rats in the same extent, to 73% of the control. Regarding the underlying mechanisms for the TC decrease, both SchO and FO up‐regulated hepatic Insig‐1 gene (181 and 133% of the control; p < 0.05), which tended (p = 0.15 and p = 0.19 respectively) to decrease the amount of hepatic nSREBP‐2 protein (61 and 66% of the control). However, neither SchO nor FO influenced hepatic 3‐hydroxy‐3‐methyl‐glutaryl‐CoA reductase gene expression (p > 0.05); SchO (but not FO) increased (p < 0.05) low‐density lipoprotein receptor mRNA in the liver. It was concluded that the decrease of total plasma cholesterol might be caused by an increased cholesterol uptake from plasma into the cells (in the case of SchO), but also by other (in the present study not tested) mechanisms.  相似文献   
77.
为方便监测水质与水下鱼群活动,本研究设计了一款面向全水域实时监测的水产养殖机器鱼,并搭建了机器鱼控制系统,开展了机器鱼三维路径跟踪控制研究。在Serret-Frenet坐标系下建立了机器鱼三维空间路径跟踪误差模型,并基于LOS制导律和李雅普诺夫理论设计了一种模糊滑模控制器,最后利用Matlab仿真对本研究提出的控制算法的有效性进行验证。仿真结果表明:所设计的控制器能使机器鱼在模型参数不确定性、外部干扰未知的情况下实现三维路径跟踪控制,其控制精度和鲁棒性明显优于常规PID与滑模控制器。  相似文献   
78.
为探讨广东东莞松木山水库鱼类群落结构特征及其与环境因子的关系,分析其结构特征在沉浮网间的差异性,在该水库设置3个采样点采用多网目刺网对鱼类进行了调查。结果显示,共采集到鱼类17种,隶属4目、6科,物种数以鲤形目为主(占58.82%)。相对重要性指数(IRI)显示,优势种为海南似鱎(IRI占比29.66%)、?(18.98%)、尼罗非鲫(18.46%)、鲢(14.85%)和莫桑比克非鲫(11.36%),其中单位努力捕捞数量(NPUE)以海南似鱎(45.72%)占优、单位努力捕捞重量(BPUE)以尼罗非鲫(34.60%)为主。聚类分析表明,鱼类物种组成在季节间无显著差异,物种数、NPUE和BPUE亦无季节变化(P>0.05)。鱼类群落物种数、NPUE和BPUE沉浮网间无显著差异(P>0.05),但鱼类数量组成沉浮网间存在显著差异(P<0.001),与海南似鱎有关,其NPUE浮网显著高于沉网(P<0.05),其他5种主要鱼类沉浮网间无显著差异(P>0.05)。透明度、pH和总磷是影响鱼类物种数量时空分布的关键环境因子。研究表明,松木山水库鱼类多样性低,可能与水面积较小、连通性低、外来种入侵及入库河道以人工排渠为主有关,为科学合理评估鱼类数量组成建议水库鱼类调查需要同时使用沉浮网。  相似文献   
79.
鱼病的化学药物防治会导致水质恶化、水产品药物残留超标或病原体耐药性增强等弊端。随着鱼类免疫学研究以及分子生物学技术的发展,鱼用基因工程疫苗的研究受到了广泛关注。系统地解析与梳理了鱼用基因工程疫苗发展的背景、意义及疫苗类型和国内外的研究与应用现状,明确现阶段我国鱼用基因工程疫苗发展面临的挑战并提出相应的发展建议,旨在为未来鱼用疫苗的开发和应用提供参考。  相似文献   
80.
ABSTRACT:   A field experiment was conducted in the Matsumae area of Hokkaido, Japan, during June and July 2002, to investigate the effects of different entrance designs on the catch efficiency of fish traps by fishing with commercial traps (entrance inclination angle [α] = 37°; funnel length of entrance [ L f ] = 22 cm) and experimental traps. The experimental traps were of the same size and similar design as commercial traps, with different entrance inclination angles (trap E1: α = 46°; E2: α = 27°; E3: α = 0°; all L f  = 22 cm) or funnel lengths (E4: α = 37°, L f  = 8 cm). In total, 2200 fish during 200 trap hauls were captured. The catch was significantly higher using both traps E2 and the commercial trap than with trap E3 ( P  < 0.05), and the catch of trap E2 was higher than that of the commercial trap. There were no significant differences in mean fish body length or the frequency distributions of body length among trap types (E1, E2, E3 and commercial). The funnel length of the entrance also affected the catch of traps. Trap E4 had significantly higher catches than the commercial trap ( P  = 0.04) when traps were deployed for a 1-day soak time. Fish body length frequency distributions did not differ between trap E4 and the commercial trap. The results showed that catch can be greatly affected by trap entrance designs.  相似文献   
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