大型海藻对氮磷吸收能力的初步研究

实验选取了经济价值较高、生态特征较为明显且研究较为深入的三种大型海藻:海带(Laminaria japonica Aresch)、鼠尾藻(Sargassum thunbergii)和龙须菜(Gracilaria lemaneiformis)作为实验材料,在模拟自然环境条件(14℃、1500lx)和适宜的氮、磷浓度(50μmol/L、5μmol/L)下,研究其在72h内对氮、磷的吸收能力。实验数据测得,海带、鼠尾藻和龙须菜对氨氮吸收速率分别为0.397μmol/g·h、0.317μmol/g·h和0.300μmol/g·h,吸收效率为66.3%、53.6%和51.2%;对磷的吸收速率分别为0.036μmol/g·h、0.030μmol/g·h和0.033μmol/g·h,吸收效率为65.2%、55.7%和58.8%。结果表明,三种海藻对氮、磷均有明显的吸收效果,吸收能力顺序为:海带>龙须菜>鼠尾藻。     

温度对几种大型海藻硝氮吸收及其生长的影响

以大型红藻真江蓠Gracilaria asiatica、脆江蓠Gracilaria chouae、蜈蚣藻Grateloupia filicina大型褐藻鼠尾藻Sargassum thunbergii、海黍子Sargassum pallidum为实验材料,研究了在10～25℃不同温度下这几种海藻对硝氮(NO3-N)的吸收和生长情况。结果表明,几种大型海藻对水体中NO3-N的吸收效果明显,其中真江蓠和脆江蓠的吸收速率15℃时最高,为0.507±0.136和0.448±0.095μmol/g·h,蜈蚣藻和鼠尾藻在20℃时最高,为0.614±0.033和0.289±0.019μmol/g·h,海黍子在25℃时吸收速率最高,为0.748±0.015μmol/g·h。结合去除效率常数来看,海黍子对NO3-N有更好的去除效果。温度变化对大型海藻的生长具有显著的影响,在20℃下大部分海藻相对生长速率达到最高,其中以脆江蓠最高,达到4.79%±0.45%/d。     

利用液相氧电极技术对鼠尾藻叶的光合及呼吸作用的初步研究

为了揭示鼠尾藻叶的生理生态适应性,利用液相氧电极技术对鼠尾藻叶进行了光合及呼吸作用的初步研究:(1)对鼠尾藻异形叶(阔叶、狭叶、气囊)的最大表观光合速率、饱和光强、光补偿点、初始量子效率、暗呼吸速率、色素含量、比叶面积和显微结构等进行了差异比较,初步探讨了鼠尾藻产生叶形变化的可能原因;(2)研究温度和盐度胁迫对鼠尾藻初生阔叶的表观光合速率(Pn)与暗呼吸速率(Rd)的影响,初步分析了鼠尾藻初生阔叶的抗逆生理,可为基于营养繁殖的鼠尾藻人工栽培提供参考.结果表明:15～24℃是鼠尾藻初生枝条生长的适宜温度范围;5℃或大于30℃的温度胁迫1h对初生阔叶的Pn有显著影响,低温(10℃以下)或高温(大于30℃)胁迫1h对Rd也有显著影响,但是恢复培养24 h后,低温胁迫组的Pn和Rd均可基本恢复正常;短期的高盐或低盐胁迫对初生阔叶的Pn均有显著影响,尤其是盐度0和盐度60组,但是处理9h后恢复培养24 h,盐度0组的Pn可恢复正常,而盐度60组的不能恢复;在整个胁迫过程中,盐度40和盐度50组均表现出较高的Rd,盐度0和盐度60胁迫对Rd均有显著影响(P＜0.05),各个盐度处理组在处理9h后恢复培养24 h,其Rd均可恢复正常.     

温度、光强和营养史对羊栖菜无机磷吸收的影响

为了探讨温度、光照和营养史对羊栖菜（Hizikia fusiforme）无机磷吸收的影响,在不同条件下培养藻体,于第0小时、第0.5小时、第1小时、第2小时、第4小时、第6小时和第9小时分别测定培养海水中磷（P）浓度,以此来计算藻体对P的吸收速率。培养条件设置为10℃、20 ℃和30 ℃3个温度梯度;0、1 500 lx和6 500 lx 3个光强梯度;营养史通过藻体在不同营养盐浓度下培养96 h后获得,其中不同P营养史设0、5 μmol·L-1和50 μmol·L-1 3个梯度,不同氮（N）营养史设0、10 μmol·L-1和200 μmol·L-13个梯度。结果表明, 羊栖菜对P的吸收速率在20 ℃时达到最大值（0.197±0.005） μmol·（h·g）-1,在10 ℃时最小值为（0.105±0.001） μmol·（h·g）-1;随着培养光强的升高,P吸收速率逐渐递增;随着营养史中P饥饿程度的增加,P的吸收速率递增;而不同N营养史处理的藻体,无氮（0 μmol·L-1）和低氮（10 μmol·L-1）处理之间无显著差异,高氮营养史（200 μmol·L-1）的藻体具有最高的P吸收速率。     

鼠尾藻对不同浓度硝酸盐的静态吸收研究

藻类修复富营养化水体中的硝酸盐的效果主要体现在对其吸收能力上。为了准确把握鼠尾藻对硝酸盐的吸收能力,在人工养殖的条件下,通过观察模拟自然海区环境条件下鼠尾藻对不同浓度硝酸盐的吸收情况,研究了鼠尾藻在不同污染程度的海区中除氮量的贡献率大小。结果表明：当硝酸态氮含量为10～30μmol.L-1时,吸收速率随着硝酸盐含量的增加而增大,在硝酸盐浓度为30μmol.L-1时吸收速率最大,但随着硝酸盐含量的继续增加,吸收速率反而降低。说明硝酸盐含量约为30μmol.L-1时,鼠尾藻对硝酸盐的吸收能力最强。     

环境因子对鼠尾藻幼苗叶绿素荧光参数的影响

为了揭示鼠尾藻幼苗的生态适应性,研究了温度(5~34 ℃)、盐度(10~50)和营养盐等环境因子对鼠尾藻幼苗叶绿素荧光参数的影响。结果表明,(1) 氮浓度高于8 mg/L或磷浓度高于1.2 mg/L,或温度高于28 ℃,对鼠尾藻幼苗的光合作用均有显著影响(P<0.05);(2) 短时间的5~15 ℃的低温胁迫或10~50盐度胁迫6 h对鼠尾藻幼苗的F_v/F_m值影响不明显;(3) 氮、磷浓度分别为2~4 mg/L和0.2~0.8 mg/L,且NH⁺₄-N∶NO^-₃-N的比值为1~3时,较利于鼠尾藻幼苗光合作用的进行。     

盐度-光照强度-温度对角毛藻生长及高不饱和脂肪酸含量的影响

为获知盐度—光照强度—温度对半咸水硅藻——角毛藻SHOU-B98生长及高不饱和脂肪酸含量的影响,实验采用L_9(3~4)正交设计探讨其在不同盐度(6、12和18)、光照强度[10、30和50μmol/(m~2·s)]及温度(10、20和30℃)组合条件下的生长及藻细胞ARA、EPA和DHA含量的变化。结果显示,盐度、光照强度、温度三因素对角毛藻SHOUB98的生长及高不饱和脂肪酸含量均有显著影响,且存在因素间的交互作用。角毛藻SHOU-B98在盐度12、光照强度30μmol/(m~2·s)和温度30℃及盐度18、光照强度50μmol/(m~2·s)和温度20℃的组合条件下生长最快,第4天后这2组做藻的生物量显著高于其他组(P0.05)。角毛藻细胞积累不同高不饱和脂肪酸的最佳培养条件也不同,细胞积累ARA的最优培养组合条件为盐度6、光照强度50μmol/(m~2·s)和温度30℃;细胞积累EPA和DHA的最优培养组合条件为盐度18、光照强度50μmol/(m~2·s)和温度20℃。研究表明,角毛藻SHOU-B98生长快且细胞脂肪酸营养价值高的培养条件为盐度18、光照强度50μmol/(m~2·s)和温度20℃的组合。     

温度和光照强度对强壮硬毛藻氮磷营养盐吸收效果的影响

为了解温度和光照对强壮硬毛藻(Chaetomorpha valida)吸收营养盐效果的影响，探索其达到最佳吸收效果的环境条件，本文研究了该藻在不同温度(5、15、25 ℃)和光照[90 000、180 000、270 000 μmol photons/(m2·s)]条件下对海水中常见营养盐成分的吸收效果。结果显示，强壮硬毛藻在5 ℃以上和90 000 μmol photons/(m2·s)光照强度以上对水体中的NH4+-N、NO2–-N和PO43–-P都有较好的吸收效果，但温度和光照对强壮硬毛藻吸收营养盐均有显著影响，在设定范围内，营养盐吸收速率与温度和光照强度均呈正相关关系。极差分析结果显示，温度的影响大于光照强度的影响。方差分析结果显示，光照强度和温度的主效应都极显著，而且具有叠加效应，吸收率最高的条件为25 ℃/ 270 000 μmol photons/(m2·s)组合，该条件下，NH4+-N、NO2–-N和PO43–-P的营养盐吸收率最高，3 h吸收率分别为(99.70±0.52)%、(99.99±0.01)%和(91.31±0.32)%。该藻的广温性吸收能力对我国北方地区低温和高温季节育苗用水和养殖尾水的净化具有非常重要的意义。     

水体环境因子对波吉卵囊藻亚硝酸盐氮吸收速率的影响

利用稳定同位素示踪剂,通过正交实验,研究了温度、光照度、盐度、pH、藻浓度对波吉卵囊藻(Ocystisborgei)亚硝酸盐氮吸收速率的影响。结果表明:温度、光照度、pH和藻浓度对波吉卵囊藻亚硝酸盐氮吸收率影响显著(P<0.05)。当温度25℃、光照度4 500 lx、pH 7.5、藻浓度4.5×105个/mL时,波吉卵囊藻对亚硝酸盐氮平均吸收速率分别为0.106μg N/(g.h)、0.118μg N/(g.h)、0.129μg N/(g.h)和0.129μg N/(g.h),显著高于其他组。单因素方差分析显示,此为波吉卵囊藻吸收亚硝酸盐氮的最优组合。通过对藻浓度的调控,可以提高波吉卵囊藻对水体中亚硝酸盐氮的吸收速率,改善虾池养殖环境,促进健康养殖。     

不同温度、光照强度和硝氮浓度下龙须菜对无机磷吸收的影响

龙须菜的细胞壁含有丰富的胶质成份,是琼胶生产的良好原料,在中国沿海已经形成了大规模的人工养殖。同时,随着中国近海富营养化现象的日趋严重,龙须菜的规模养殖被认为是缓解海水富营养化的一条有效途径。以探讨龙须菜的生物修复功能为目的,研究了龙须菜对无机磷吸收的基本特征以及不同温度、光照强度和硝氮浓度对其的影响。整个实验在实验室可控条件下进行,分别设置了3个不同温度:15、23和31 ℃;3个不同的光照强度:0、30和200 μmol photons/(m²·s)和3个不同的硝氮浓度:0、30和200 μmol/L,测定了在不同的条件下培养的龙须菜对无机磷吸收的动力学曲线。结果表明:龙须菜对无机磷的吸收动力学曲线符合典型的米氏方程特征,并且吸收能力随温度和硝氮浓度的升高而增大,吸收效率在较低温度(15 ℃)和接近自然海水的硝氮浓度条件(30 μmol/L)下较高;而低光照强度下［30 μmol photons/(m²·s)］的吸收能力和吸收效率均高于黑暗和高光强条件［200 μmol photons/(m²·s)］。由此可见,温度、光照强度及硝氮浓度等环境因子都影响龙须菜对无机磷的吸收特性,但是,其具体的机制仍需进一步深入研究。     

Achieving sustainable aquaculture: Historical and current perspectives and future needs and challenges

Important operational changes that have gradually been assimilated and new approaches that are developing as part of the movement toward sustainable intensive aquaculture production systems are presented via historical, current, and future perspectives. Improved environmental and economic sustainability based on increased efficiency of production continues to be realized. As a result, aquaculture continues to reduce its carbon footprint through reduced greenhouse gas emissions. Reduced use of freshwater and land resources per unit of production, improved feed management practices as well as increased knowledge of nutrient requirements, effective feed ingredients and additives, domestication of species, and new farming practices are now being applied or evaluated. Successful expansion into culture of marine species, both off and on shore, offers the potential of substantial increases in sustainable intensive aquaculture production combined with integrative efforts to increase efficiency will principally contribute to satisfying the increasing global demand for protein and food security needs.     

Fish assemblage associations and thresholds with existing and projected oil and gas development

Energy development threatens fish and wildlife resources worldwide. This study used constrained ordinations to show fish assemblage structure associated with oil and gas well densities in the Colorado River Basin, Wyoming, but well densities explained only 6.4% of assemblage structure when compared to other factors. Threshold Indicator Taxonomic ANalysis showed significant negative threshold responses by some species to small levels of development (<0.15 wells km^?2), whereas positive thresholds were less distinct. Some native and imperilled species could be disproportionately affected if future oil and gas development proceeds in a manner that will impact aquatic resources. Although existing development has not substantially influenced regional fish assemblage structure, it appears to affect a subset of species. Understanding assemblage‐level responses to development can help land managers determine appropriate development levels, prioritise areas for monitoring associated with future development and identify where land protection measures may be needed to offset potential risks.     

Gar biology and culture: status and prospects

Many lepisosteid populations in North America have declined and many are now threatened as a consequence of habitat loss and alteration and commercial and sport overfishing. Over the last two decades, morphological, histological and molecular studies allowed distinguishing between different phases of development and the nutritional condition of larvae. Ontogeny of the digestive enzymes of gar larvae indicated the possibility to feed them artificial feeds since early developmental stages. An in vitro digestibility system to test different feed ingredients has been used. Important characteristics of artificial diets were identified through different feeding experiments. Endocrinological studies showed the feasibility of altering larval development and the digestive capacity of larvae. Cloning of gar growth hormone opened new avenues to enhance growth in the gars. Plasmatic vitellogenin was isolated and purified, to develop a competitive enzyme‐linked immunosorbent assay, which allowed the straightforward separation of males from females to establish appropriate proportions for reproduction and also was used to evaluate hormonal protocols to induce gonad recrudescence and spawning. This review analyzes the biology, ecology and physiology of different gar species as a basis for their domestication, mass production of larvae for repopulation experiments and for the culture of commercial‐size gar.     

Esophagoscopy and gastroscopy in dogs and cats. Technics and indications

A report is presented of esophagoscopy and gastroscopy in cats and dogs using flexible endoscopes. Following consideration of the basic equipment, an account is given of patient preparation and anesthesia, topography, investigation technique and normal findings. Diagnostic potential, indications and risks involved are discussed.     

加快城乡统筹，推进我国农垦体制创新与经济发展的研究与思考

“十一五”以来，我国农垦加快体制机制改革、结构调整和经济增长方式的转变的步伐，参与市场竞争，努力提升企业和产品竞争力，经济社会事业发展较快，对国家的贡献提升，职工收入、生活质量明显提高和改善，示范引领作用不断增强。本文针对农垦体制机制创新进展滞缓，战略定位与发展方向不明，经济增长方式转变和结构调整缺乏资本、人才、技术的支撑，没有处理好改革、发展、稳定、民生的关系，投资匮乏，发展后劲不足，人才短缺和劳动力素质低下的现状，提出在未来农垦体制机制创新中要特别关注改革方向、目标设定与评估，改革要在现行法律法规的框架内运作，改革时机的选择，处理好改革发展稳定与民生的关系，调整好内部利益分配关系，自觉融入区域经济，与地方协同发展等问题。为了促进农垦的发展，建议国家加大对农垦体制机制创新、现代农业建设、国有农场土地资源的保护、社会保障体系的完善等财政和政策的支持力度。     

添加植酸酶日粮不同磷水平和钙磷比对生长肥育猪血液生化指标和骨骼性能的影响

本试验利用饲养试验方法,研究玉米-豆粕型日粮中添加植酸酶时不同磷水平和钙磷比对生长肥育猪血清指标和骨骼性能的影响。试验选用162头20kg左右的杜长大三元杂交猪进行2×3(磷水平×钙磷比)因子饲养试验,试验分2个阶段进行,前期为生长期体重在20-60kg,后期为肥育期体重为为60-100kg。结果表明:添加植酸酶日粮磷水平对血清磷含量和碱性磷酸酶的活性影响显著(P<0.05);钙磷比对血清钙和血清磷含量的影响显著(P<0.05);添加植酸酶日粮磷水平和钙磷比对生长肥育猪骨骼性能的影响不显著(P>0.05)。在添加植酸酶条件下,降低日粮磷水平不影响猪的正常生长发育。     

奶牛酮病发病机理研究进展

结合国内外目前研究状况较为详细的综述了奶牛酮病的病因与发病机理,并分析了奶牛酮病发生的生化机制。旨在对临床实践中很好的认识诊断和群体监控奶牛酮病提供较为系统的理论依据,保证奶牛群的高产和稳产,从而创造良好的经济效益。     

温度与盐度对老年低额蚤和蚤状蚤生长及生殖的影响_

温度与盐度对老年低额蚤和蚤状蚤生长及生殖的影响王丹丽，李明云，杨天勇，胡章（宁波大学，３１５０１０）关键词老年低额　，蚤状　，温度，盐度，生长，生殖ＥＦＦＥＣＴＳＯＦＴＥＭＰＥＲＡＴＵＲＥＡＮＤＳＡＬＩＮＩＴＹＯＮＧＲＯＷＴＨＡＮＤＲＥＰＲＯＤＵＣＴ...     

川渝地区鸡皮刺螨的流行与综合防治

鸡皮刺螨是鸡的一种体外寄生的节肢动物,流行十分广泛,对养殖业发展有严重影响。为了解鸡皮刺螨的发病情况,对川渝两地的126个鸡场进行流行病学调查,感染率高达71%。同时,介绍了鸡皮刺螨的生活史、危害及防治措施,是防制鸡皮刺螨不可多得的资料。     

Composition and diversity of fish and fish catches in closures and open-access fisheries of Kenya

Abstract  Catch composition, relative abundance and diversity of fish catches in open access and three old fisheries closures were compared and contrasted with previous ecological studies. There was less variation in catch community composition among the fishing grounds than the closures, suggesting that fishing has homogenised catch composition. The trap survey found that some parrotfish [ Leptoscarus vaigiensis (Quoy &Gaimard), Calotomus carolinus (Valenciennes) and Scarus ghobban Forsskål] were relatively more common and that some important predators of macro-invertebrates [ Balistapus undulatus (Mungo Park) and Cheilinus chlorourus (Bloch)] were less common in the fishing grounds than closures. Unexpectedly, and in contrast to visual census results, cumulative number of species in catch surveys was higher in open access than closures sites. This may result from fishers covering more area and habitat or a reduction in the catch of competitively subordinate and rare species by aggressive, early-caught fish that can dominate bait. Comparisons of ecological visual census surveys and fisheries-dependent methods indicated that small differences in catch composition can reflect larger ecological differences and that baiting methods can underestimate biodiversity. Ecological impacts of fishing and large-scale changes in marine ecosystems must be considerable given the many fisheries-dependent assessments report modest changes.