共查询到20条相似文献，搜索用时 610 毫秒
1.
2.
为研究宽体金线蛭对稻草基质的产卵适应性,分别建造以稻草作基质的产卵平台和以土壤作基质的产卵平台以及稻草基质产卵平台和土壤基质产卵平台交错分布的混合型产卵平台,并进行了对比试验。分别统计稻草基质组和土壤基质组中每个平台采集的卵的总数量、总体质量和孵化出苗的卵的数量,计算每尾宽体金线蛭的平均产卵数、卵体质量和孵化率；分别统计混合组中稻草基质产卵平台和土壤基质产卵平台采集的卵的总数。结果显示:稻草基质组和土壤基质组在平均产卵数、卵平均质量和孵化率方面差异不显著；混合组中,稻草基质产卵平台与土壤基质产卵平台的产卵数差异显著,说明宽体金线蛭对稻草基质的产卵适应性良好,相对于土壤基质,宽体金线蛭产卵时对稻草基质存在选择性偏好。 相似文献
3.
为研究膨胀蛭石对宽体金线蛭卵孵化的影响,在(25±1)℃的恒温条件下,分别用膨胀蛭石和土壤(对照组)作为孵化基质孵化宽体金线蛭卵,并进行了对比试验。试验组和对照组各设5个重复,测量并计算不同基质条件下宽体金线蛭卵的平均孵化期、平均孵化率和孵出幼体的平均体质量。结果显示:膨胀蛭石组中宽体金线蛭卵的平均孵化期、平均孵化率和孵出幼体的平均体质量分别为11.16、11.40、11.08、11.52和11.32 d,98.04%、100%、94.12%、96.08%和96.08%,0.025 6、0.025 9、0.025 4、0.025 2和0.025 7g;土壤组中宽体金线蛭卵的平均孵化期、平均孵化率和孵出幼体的平均体质量分别为12.12、12.26、12.16、12.28和11.94 d,88.24%、92.16%、90.20%、94.12%和90.20%,0.025 1、0.024 8、0.024 5、0.024 7和0.025 0 g。各组对应数据之间均存在显著性差异(P0.05)。试验结果表明:以膨胀蛭石作孵化基质,对宽体金线蛭卵的孵化期、孵化率和孵出幼体的体质量有显著影响,膨胀蛭石适宜作为宽体金线蛭卵的加温孵化基质。 相似文献
4.
为研究宽体金线蛭的人工繁殖技术,以野外采捕的宽体金线蛭成体作试验材料进行室外繁殖和室内孵化试验,统计其产茧量、空茧数、孵化率。试验结果:约5 000 kg种蛭共产卵茧351.5 kg;当种蛭投入产茧床时的土壤湿度为60 %时,产茧量达到最大值;当孵化箱的土壤湿度为40 %时,空茧数显著低于湿度为20 %、50 %、70 %的组(P<0.05),孵化率显著高于湿度20 %、50 %、70 %组(P<0.05),空茧数、孵化率与湿度30 %组差异不显著(P>0.05)。结果表明:宽体金线蛭人工繁殖采用室外繁殖、室内孵化的方案可行。当投入产茧床时,60 %的土壤湿度有利于种蛭钻进土壤中产茧,显著提高种蛭的产茧量。孵化箱的土壤湿度控制在30 %~40 %时,孵化率最高。 相似文献
5.
为进一步了解宽体金线蛭的食性偏好,在室内养殖条件下,分别用螺(环棱螺)、鸭血、菲牛蛭配合饲料等3种饲料投喂宽体金线蛭,并对其生长情况进行了对比。结果表明,在室内养殖的水温、pH、溶解氧近似的条件下,经过129 d养殖,投喂螺组宽体金线蛭的体质量呈上升趋势,平均体质量增长率为247.12%,平均日增长0.04 g/d;投喂鸭血组和配合饲料组宽体金线蛭的体质量均呈下降趋势,平均体质量增长率分别为-50.71%和-41.71%。试验表明,3种饲料中,螺较适合作为宽体金线蛭的饲料,鸭血和菲牛蛭配合饲料则不适合作为其饲料。 相似文献
6.
比较有机孵化基质对宽体金线蛭卵茧孵化效果和不同开口饵料对苗种生长发育的影响。孵化基质分别为土壤、牛粪有机肥、蘑菇菌渣,开口饵料分别为螺蛳、漂螺。试验结果显示,蘑菇菌渣+土壤组卵茧孵化率高达98.89%,显著高于土壤组和蘑菇菌渣组(P<0.05);幼蛭各生长指标显著高于土壤组、蘑菇菌渣组、有机肥组及有机肥+土壤组(P<0.05);混合组幼蛭各生长指标均显著高于未添加土壤组(P<0.05)。5种不同孵化基质孵化率依次为蘑菇菌渣+土壤>土壤>有机肥+土壤>有机肥>蘑菇菌渣。不同开口饵料的试验比较发现,漂螺组幼蛭成活率为72.50%,显著高于螺蛳组和螺蛳+漂螺组(P<0.05),漂螺组和螺蛳+漂螺组幼蛭体质量显著高于螺蛳组(P<0.05)。生长效果依次为漂螺组>螺蛳+漂螺组>螺蛳组。试验结果表明,蘑菇菌渣可以作为宽体金线蛭卵茧孵化基质;无厣结构的漂螺更适宜作宽体金线蛭幼蛭的开口饵料。 相似文献
7.
南四湖宽体金线蛭生物学观察及人工繁殖初探 总被引：1，自引：0，他引：1
初步观察和了解了宽体金线蛭的形态特征、生活习性、繁殖特性，并进行了人工繁殖试验。在10m^2的面积内，放养种蛭100条，产卵茧200余枚，繁殖幼蛭5000余条。 相似文献
8.
9.
为探究不同放养时间段对宽体金线蛭(Whitmania pigra Whitman)繁殖时产茧率的影响,找到繁殖时最佳需要放养的时间,选用体重规格为20.00 g±2.00 g的宽体金线蛭亲本,按5 d间隔设放养时间不同的7个试验组,其放养时间分别为10 d、15 d、20 d、25 d、30 d、35 d、40 d,将亲本放养于聚乙烯泡沫箱中,观察其繁殖产茧及孵化情况。结果表明:30 d及35 d组产茧率最高,分别为11.71%和14.63%;10 d组产茧率最低,为3.97%;40 d组孵化率最低为95.38%;其余组都为100%。因此,放养繁殖时间在30~35 d时产茧率和孵化率较好,经济效益最佳。 相似文献
10.
11.
Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean 
下载免费PDF全文
下载免费PDF全文 The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna. 相似文献
12.
Liping Li Rui Wang Wanwen Liang Xi Gan Ting Huang Yan Huang Jian Li Yunliang Shi Honglin Luo Ming Chen 《广西水产科技》2014,(1)
Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China. 相似文献
13.
In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg. 相似文献
14.
15.
Growth hormone (GH) and reproduction: a review 总被引：5，自引：0，他引：5
Florence Le Gac Odile Blaise Alex Fostier Pierre-Yves Le Bail Maurice Loir Brigitte Mourot Claudine Weil 《Fish physiology and biochemistry》1993,11(1-6):219-232
Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations. 相似文献
16.
Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL?1 (1.25 ng well?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation. 相似文献
17.
Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection 下载免费PDF全文
下载免费PDF全文 G Sharon M Pimenta‐Leibowitz M C L Vilchis N Isakov D Zilberg 《Journal of fish diseases》2015,38(1):67-74
Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality). 相似文献
18.
William King V David L. Berlinsky Craig V. Sullivan 《Fish physiology and biochemistry》1995,14(6):489-500
Plasma estradiol-17 (E2), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E2 and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E2 and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass. 相似文献
19.
Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide 总被引：1，自引：0，他引：1
Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response. 相似文献
20.
Sandra García‐Garrido Ismael Hachero‐Cruzado Carlos Rosas Pedro Domingues 《Aquaculture Research》2013,44(11):1741-1751
Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg?1 protein) than essential amino acids (425.82 ± 9.15 g kg?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting. 相似文献