Long-term effects of stocking density on survival,growth performance and marketable production of the sea urchin <Emphasis Type="Italic">Strongylocentrotus intermedius</Emphasis>

Sea urchins were stocked at a density of 15 (D15), 30 (D30), 45 (D45) and 60 (D60) urchins/cage (0.3 m long × 0.2 m wide × 0.4 m high) in a laboratory culture environment for 16 months. The wet body weight (BW) and test diameter growth were monitored at 2-month intervals during the experiment. At the conclusion of the experiment, the surviving sea urchins were counted and the gonad wet weight (GW) and gonad color were measured. Specific growth rate (SGR) of body weight, survival rate (SR), gonad index (GI), gonad color difference (ΔE ₀₀), coefficients of variation (CV) of BW, GW, GI and ΔE ₀₀, total biomass yield (TY) and total gonad yield (TGY) per cage were calculated. Two marketable yield variables, graded according to gonad index, i.e., marketable biomass yield (MY) and marketable gonad yield (MGY), were also calculated. Coefficient of variation of final body weight (FW) and final test diameter (FTD) of sea urchins increased as the stocking density increased, indicating the existence of adverse social interactions. These adverse social interactions detrimentally affected FW, FTD, SGR, GW and GI (P < 0.01). Although SR decreased with the increasing densities, no statistical significant difference was detected. Sea urchins at D15 had the lowest gonad color difference (ΔE ₀₀) (P < 0.05). However, statistically equal CV of ΔE ₀₀ indicates this density effect was not a result of adverse social interactions. TY and TGY increased with increased density and can be described by the following equations: TY = 84.18X ^0.64, R ² = 0.999 and TGY = 24.16X ^0.38, R ² = 0.979. However, the MY and MGY were not significantly different among stocking densities. The results of this study demonstrate that in intensive culture S. intermedius at low stocking density can achieve high growth rate, gonad index and desirable color without decreasing the marketable yield. Farmers should choose to culture S. intermedius at low stocking densities.     

龙鱼的饲养与疾病防治

龙鱼（Scleropages formosus）在东南亚、港澳台地区和海外华人集中的地方常被当作宠物饲养,将它视为神鱼,据称可以旺家镇宅、避邪,故又享有“风水鱼”之美誉。 龙鱼体形独特,口大,下颚有两条长须,体侧鳞片宽大,在阳光照耀下闪烁着耀眼的光芒。它的游姿舒缓优雅,显得高贵祥和,给人以愉悦之感。     

牛磺酸对鲤鱼诱食活性的初步研究

用牛磺酸作为诱食剂,以0.2%、0.4%、0.6%、0.8%的剂量将牛磺酸添加到基础饵料中,以基础饵料为对照,以鲤鱼为对象进行诱食活性试验,用one-way ANOVA检验统计分析,结果表明:牛磺酸对鲤鱼有明显的诱食作用,其中0.4%组诱食效果最佳,极显著地高于对照组(P<0.01)。     

Evaluation of three non‐genetically modified soybean cultivars as ingredients and a yeast‐based additive as a supplement in practical diets for Pacific white shrimp Litopenaeus vannamei

Two growth trials and a physiology assessment were conducted to evaluate three non‐genetically modified (GM) soybean cultivars as ingredients in practical diets for Pacific white shrimp, Litopenaeus vannamei. In addition, a commercially available fermented yeast product was evaluated as dietary supplement. For the growth trials (46 and 35 days, respectively, for trials 1 and 2), the basal diet was primarily composed of soybean meal (SBM), fishmeal (FM), whole wheat, corn protein concentrate, poultry meal (PM, pet food grade) and corn starch. Non‐GM cultivars were processed with novel methodologies to produce Navita? ingredients (N1, N2 and N3) which were incorporated at low (L) or high (H) levels into the experimental diets, in partial replacement of FM and full replacement of conventional SBM. The last two formulations incorporated the fermented yeast for a total of nine experimental diets (Table 1 ). Results from the growth trials indicate that shrimp fed diet 5 (HN2) exhibited significantly lower (p < .05) weight gain as compared to shrimp fed diets 1 and 2 (basal and LN1, respectively) in trial 1, as well as compared to animals fed diets 1, 2, 3 and 8 (basal, LN1, HN1 and basal + yeast) in trial 2. The feed conversion ratio significantly increased for shrimp fed diet 5, in contrast with shrimp fed diets 1, 2, 3 and 8 in trials 1 and 2, as well as compared to shrimp fed diets diet 6 (LN3) in trial 2. For the physiological assessment (stress and immune responses), only the effects of diets 1, 3, 8 and 9 (basal, HN1, basal + yeast and HN1 + yeast, respectively) were investigated. Granular cell counts were significantly higher for shrimp fed the yeast‐containing diets. Haemolymph glucose and haemolymph packed cell volume were significantly reduced for shrimp fed diets 3, 8 and 9. No significant differences were observed in total haemocyte counts, hyaline cells counts, semi‐granular cells counts, haemolymph protein, haemocyte phagocytic capacity and haemocyte respiratory burst activity. Results of this work indicate that selective soy breeding technology coupled with novel processing options has the potential to increase the nutritional value of conventional SBM for shrimp feeds. Trends on immune responses were more difficult to elucidate possibly due to the limited length of the feeding trial.     

利用环境DNA技术探测南海西沙鲸类物种多样性

本研究通过提取南海西沙海域水体样本的环境DNA,利用鲸类线粒体12S r RNA和16S r RNA通用引物进行扩增和高通量测序,并结合目视观测的结果探讨环境DNA技术在鲸类物种多样性研究中的应用前景。结果显示,4种通用引物在鲸类鉴定方面具有一定的有效性,利用4种通用引物在西沙海域19个站点的样品中检测到5种鲸类,分别为热带斑海豚(Stenella attenuata)、长吻飞旋海豚(Stenella longirostris)、弗氏海豚(Lagenodelphis hosei)、小布氏鲸(Balaenoptera edeni edeni)和短鳍领航鲸(Globicephala macrorhynchus),采样过程中观测到的3种鲸类分别为:热带斑海豚、长吻飞旋海豚和瑞氏海豚(Grampus griseus)。两种方法检获的优势物种一致,利用环境DNA技术检测到了未被观测到的物种。结合引物Cet-12S和Marver3的检测结果可以涵盖所有站点(n=17)和所有鲸类物种(n=5),表明针对不同基因片段的引物结合使用有利于检测效果的提高。对于检出的鲸类序列和物种数,4种引物之间不存在显著...     

运动强度对罗氏沼虾运动行为和能量代谢的影响

为查明运动过程中罗氏沼虾的行为特征及其与肌肉能量代谢的关系,实验设置了对照、低、中、高4种不同强度的游泳和弹跳实验,研究了运动后罗氏沼虾的行为、能量来源和相关代谢酶活性。游泳强度通过在特定时间内设置不同的水流速度来确定,对照、低、中、高强度的水流速度分别为0 (自由运动)、5 (200 min)、10 (200 min)和15 cm/s (游泳至疲劳)。弹跳强度通过在特定时间内设置不同触碰频率来确定,对照、低、中、高强度的触碰频率分别为0 (自由运动)、0.033 (5 min)、0.050 (5 min)和0.067 Hz (弹跳至疲劳)。结果显示,罗氏沼虾各运动组游泳足和尾肢的最大摆动频率和最大摆动幅度均显著高于对照组。各运动强度组肌肉蛋白质含量与对照组之间无显著差异,肌肉糖原含量均显著小于对照组,低强度游泳组肌肉甘油三酯含量小于对照组。中、高强度游泳组游泳足肌肉乳酸脱氢酶(LDH)活性和乳酸含量显著高于对照组,低强度游泳组游泳足肌肉丙酮酸脱氢酶、苹果酸脱氢酶和脂肪酶活性显著高于对照组。无论弹跳强度高低,罗氏沼虾腹部肌肉LDH酶活性和乳酸含量均显著高于对照组。研究表明,罗氏沼虾通过...     

向日葵菌核病菌毒素的生产及其生物活性的测定

首次报道了向日葵核病菌[Sclerotinia sclerotiorum (Lib.) de Bary]在离体，活体培养条件下均能产生草酸毒素，研究表明，在扫描电镜下，Ca^2 离子结晶可形成草酸钙晶体，且多分布在孔及表皮毛周围；该菌的培养滤波及粗毒素对种子萌发胚轴伸长和幼草生长等都有毒害或抑制作用。     

大豆耐盐基因的PCR标记

 以大豆耐盐品种和盐敏感品种及“耐盐品种×盐敏感品种”组合的F2群体为试验材料,筛选和鉴定与大豆耐盐性基因紧密连锁的PCR标记,旨在建立快速准确的大豆耐盐性鉴定方法。利用BSA法,对耐(敏)盐品种池和一个组合F2的耐(敏)盐池进行了鉴定,获得一个共显性标记。经F2分析,在盐敏感个体中仅扩增出约600bp的特异片段;在耐盐性个体中扩增出约700bp的特异片段或2个特异片段(700bp/600bp),经过连锁值测定,表明该标记与大豆耐盐基因位点紧密连锁。此外,该标记在其它2个组合F2群体及12个耐盐品种和13个盐敏感品种中得到验证,表明此标记可用于大豆耐盐种质鉴定及大豆耐盐遗传育种的分子标记辅助选择,使大豆耐盐性室内鉴定成为可能。为此,大豆耐盐性基因的分子标记及其获得方法和应用已申请了中华人民共和国发明专利。     

水稻的分蘖规律与生产力研究

以冀粳１４号的主茎和不同蘖位１￣４次分蘖为材料,研究了水稻的分蘖规律与分蘖生产力。结果证实,中晚熟水稻品种主茎有２个蘖位转折期,主茎３蘖位为第１蘖位转折点,主茎Ｎ蘖位为第２蘖位转换点;在主茎１－Ｎ－１蘖位中,在水稻具有ｎ－３的叶、蘖同伸规律的同时,主茎ｎ蘖位上一次分蘖与主茎ｎ－２蘖位下一次分蘖 具有ｎ－２的蘖、蘖同伸规律,即纵向上主茎每长２片叶,横向上分蘖次数增加１次的规律;最优蘖位形成的规律是：在所有同次分蘖中,Ｎ－１和Ｎ－２蘖位１次分蘖生产潜力最大,Ｎ－３和Ｎ－４蘖位２次分蘖生产潜力最大,Ｎ－５和Ｎ－６蘖位３次分蘖生产潜力最大;合理利用强优势中位蘖具有１８％左右的增产潜力。     

陡坡弯道体型水力特性的试验研究

卡群一级电站泄水陡坡于１９９５年底建成运行后，由于弯道体型设计不合理，当泄水流量为２８ｍ３ｓ－１（设计流量为６０ｍ３ｓ－１，加大流量为７０ｍ３ｓ－１）时，弯道水流已甩出凹岸边墙，而弯道凸岸基本上处于无水状态。对此，我们进行了模型试验研究。经多种修改方案试验比较，其中在陡坡段设置消能栅、弯道段设置导流消能板（简称综合式）的方案，既能较好地控制急流弯道水流流态，消除下级陡坡中水流折冲现象，又不改变原来弯道体型，节省了工程量。本文除对不同方案的体型布置及流态作简述外，着重对综合方案的水力特性及效果作分析和阐述