白洋淀渔业资源现状及增殖意见

<正> (一)、白洋淀概况白洋淀是大清河中游的天然洼淀,由大小90多个淀泊和3,700多条沟濠组成。总面积46万亩。周边堤防全长230公里。白洋淀上游有潴龙河、孝义河、唐河、府河,漕河、瀑河、萍河、白沟引河等九条河流,呈扇形汇流入淀,称为“九河下稍”。下游经海河与渤海相通。由于白洋淀水域面积广阔,上游有河流带来充足的水量和丰富的养分,下游又和海河、渤海沟通,使白洋     

白洋淀水产减产的原因及其发展途径的探讨

<正> (一) 白洋淀是华北地区大塑的天然湖泊之一,位于十河下梢(即南漾河、北瀑河、府河、萍河漕河、孝义河、唐河、沙河、磁河及白沟引河)流域总面积32200平方公里,行政上包括河北保定全部,石家庄地区的行唐、新乐、无极、深泽四县,北京市房山县和丰台区一部,山西省的灵丘县和河北省张家口地区阳原县一部,共计31个县市。四周堤防环绕,南部有千里堤联接淀南新堤,北有新安北堤,西部有障水、西南有四门堤,淀区总面积312平方公里(46.8亩),其中安新县占86％,任丘占9％,雄县占4％,容城占1％。全淀是由大小九十九个淀泊组成,淀内沟壕纵横,园田交错,小岛似的村庄星罗棋布,有纯水村34个,人口共56000人,周边半旱村50个,约150000人。淀区人民依靠这块水域进     

三峡水库正常运行下库区干流浮游动物群落时空格局特征研究

2016年7月-2017年3月对三峡水库正常运行下库区干流浮游动物进行了调查。共鉴定浮游动物45种,其中原生动物9种,轮虫12种,枝角类13种,桡足类11种。浮游动物群落结构存在显著时空异质性,冬季浮游动物物种数最少,夏季、秋季、春季浮游动物物种数较多,密度以夏季和春季较高(96340.5 ind.L^-1 和101605 ind.L^-1),以秋季和冬季较低(54884 ind.L^-1 和57035 ind.L^-1)；坝前秭归江段浮游动物密度最高,沿坝前江段溯河而上直到库尾流水江段浮游动物密度呈现降低的趋势。浮游动物优势种主要以耐污性的种类为主,物种多样性指数在时间方面以秋季最高,均匀度指数以秋季和冬季较高；空间方面,除万州调查江段,物种多样性指数和均匀度指数均呈现库首的秭归、巫山调查江段和库中的云阳调查江段〉库尾的涪陵调查江段〉回水末端的江津调查江段的趋势。聚类分析表明三峡水库蓄水运行后,浮游动物群落结构在水库的纵轴上表现出明显的分布梯度。浮游动物群落结构和环境因子的冗余分析(RDA)表明,水温、叶绿素a、总磷、溶解氧、铜、汞、挥发酚、石油类是与三峡干流浮游动物群落结构相关性较强的环境因子。     

巢湖流域河湖系统水环境因子分布特征及营养状态评价

为解析巢湖流域水环境因子空间分布特征，监测了巢湖及其环湖河流33个采样点水环境因子，并采用水质指数（WQI）对其营养状态进行了评价。结果表明：（1）巢湖流域河湖系统巢湖与河流之间及河流与河流之间所有水质参数（除水温外）和WQI指数均存在显著性差异，巢湖流域河湖系统水环境在营养梯度上呈现明显的空间格局，表现在东巢湖水质优于西巢湖；杭埠河、柘皋河、裕溪河水质优于兆河、白石山河、派河、南淝河；依据WQI指数，东巢湖、西巢湖、杭埠河、柘皋河、裕溪河水质为较好，兆河、白石山河、派河、南淝河水质为中等；（2）相较以往研究，本研究中西巢湖水质无明显变化，东巢湖水质略有下降，白石山河和兆河由原来的清水型河流转变为污染严重型河流，污染程度加重，其余环湖河流水质无明显变化；（3）应加强巢湖入湖河流氮源的管理和控制，并加强对小型流域的持续监测，深入了解小型支流在整个营养物质输送中所起的作用。     

汾河太原段轮虫多样性及群落结构的动态变化

调查汾河太原段轮虫群落结构的时空变化，探讨轮虫群落结构动态变化规律及其与环境理化因子的关系，为汾河太原段浮游动物动态预测和多样性保护提供必要信息，从生态系统的角度客观评价水质污染状况与水体富营养化程度。在汾河太原段设置采样点7个，于2014年3-12月对轮虫和水体理化指标进行逐月调查。共检出轮虫98种，隶属3目21科33属。全年优势种是长肢多肢轮虫（Polyarthra dolichoptera）和螺形龟甲轮虫（Keratella cochlearis）。调查期间月均检出轮虫28种，轮虫丰度变化范围为153 ~ 1 440 个/L，生物量为0.08～0.89 mg/L；种类数、丰度和生物量均表现为枯水季较低，丰水季最高。群落结构相似性分析表明不同营养状态水体之间差异显著，轮虫丰度、生物量、Shannon-Wiener 多样性指数和Pielou均匀度指数均存在明显差异；中等营养条件的指示种为卵形无柄轮虫（Ascomorpha ovalis）和单趾狭甲轮虫（Colurella unicauda），指示轻度富营养的指示种为柔软龟甲轮虫（Keratella delicata），中等富营养水体的指示种则为臂尾轮属的种类。冗余分析结果显示环境变量对轮虫群落结构变异的解释率为 41.3%，水温、叶绿素a 、溶解氧、总氮等因子是影响轮虫时空分布的主要因素。轮虫群落结构特征可以指示水体的营养状态。     

白洋淀水域夏季细菌群落结构及与环境因子的关系

为了解白洋淀水域细菌多样性,于夏季采集水样进行水质和微生物群落结构分析。水质分析显示,白洋淀平均酸碱值(pH)为7.95,溶解氧(DO)为16.67 mg/L,属于偏碱性湖泊且含氧量丰富。通过Illumina NovaSeq6000高通量测序分析微生物群落结构表明:白洋淀不同采样点Chao1指数、Ace指数均较高,Shannon指数为7.151~8.443,Simpson指数为0.986~0.992,反映出白洋淀各采样点微生物群落多样性丰富、稳定性好,且细菌丰富度和多样性均以光淀(GD)最高。变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)、蓝细菌门(Cyanobacteria)、拟杆菌门(Bacteroidetes)和放线菌门(Actinobacteria)是湖水的优势菌门,丰度之和能达到90%,且以变形菌门(Proteobacteria)为绝对优势菌门,丰度为44.15%~60.18%;在属水平上烧车淀(SCD)和枣林庄(ZLZ)以多核杆属(Polynucleobacter)为第一优势菌属,其余采样点优势菌属为unidentified_Cyanobacteria。CCA(canonial correspondence analysis)分析表明,pH和DO是影响白洋淀细菌群落结构的主要环境因子。     

条纹斑竹鲨的胚胎发育

观察了室内培育的条纹斑竹鲨自然生产的受精卵形态和胚胎发育过程。结果表明，条纹斑竹鲨受精卵个体较大，卵黄略呈椭圆形，长径为25.91～36.16 mm，短径为13.56～19.44 mm。受精卵外裹有棕褐色的卵鞘，鞘长75.25～107.30 mm，鞘宽33.39～47.70 mm，鞘厚15.82～24.65 mm，卵鞘坚韧而略有弹性。在水温28.0 ℃、盐度26.2～28.8条件下，受精卵经65～80 d发育孵出幼鱼，胚胎发育分为23期，参照硬骨鱼类胚胎发育各期名称给予命名。初孵幼鱼全长121.82～166.80 mm，体重5.30～18.22 g，已具成鱼的外形特征，但体内尚存卵黄，体外卵黄少许或消失。胚体长度（L/mm）与孵化时间（D/d）呈线性相关，L=2.1368D－11.175（R= 0.9862）；胚体重（M/mg）与孵化时间（D/d）呈幂函数关系，M=0.0001D^4.3763（R² = 0.9579）；胚体重（M/mg）与胚体长度（L/mm）呈幂函数关系，M = 0.0005L^3.4278（R²=0.9822）。     

连环湖两水体浮游动物群落结构特征及水质评价

为探究连环湖阿木塔与牙门喜湖区浮游动物群落结构特征及水生态现状，于2018年6月～2019年5月对连环湖两水体进行了一年调查采样。调查结果显示，共检出浮游动物75种，其中原生动物20种，轮虫21种，枝角类15种，桡足类19种。优势种16种，其中原生动物12种，轮虫和枝角类各1种，桡足类2种，浮游动物群落结构趋于小型化。浮游动物年均丰度为1060ind./L，年均生物量为2.930mg/L，夏季平均丰度与生物量最大。Shannon-Wiener多样性指数（H''）、Pielou均匀度指数（J）和Margalef丰富度指数（D）年均值分别为1.09、0.36和1.56，多样性因季节不同而有所变化，各样点间并不存在明显差异。相关性分析显示，水温和DO是影响连环湖两水体浮游动物群落结构变化的决定性因子，pH是影响浮游动物种类、丰度的重要正相关因子而透明度为负相关因子。冗余分析(RDA)显示，TN、TLI和叶绿素a也是影响浮游动物群落结构的重要因素。水体理化指标和多样性指数的综合评价结果表明，连环湖两水体目前水质状况整体为α-中污型、轻度富营养水平。     

应用线性相关剖析白洋淀水位变化与渔获量的关系

<正> 白洋淀在河北省中部,是冀中平原与滨海平原地区的一个交接冲积洼地。西面有唐河、府河、漕河、南瀑河和北瀑河,南面有流量较大的潴龙河,与海河相通的大清河自安新城内横贯白洋淀至淀东的赵北口。后由于水利工程建设,沥水汇集入淀,出口由枣林庄4孔和25孔大闸,通过赵王新河、大清河流入海河。     

几种化学物质对西施舌幼虫附着和变态的诱导技术

采用添加不同化学诱导物的方法，研究了肾上腺素（EPI）、氨基丁酸(GABA)、L-多巴（L-DOPA）、Ca²⁺对西施舌眼点幼虫附着和变态的诱导作用，确定了化学诱导物 最佳诱导浓度。结果表明,EPI对西施舌附着和变态的诱导效果最为显著，当EPI浓度为10^-4 mol·L^-1时，附着率及变态率分别为88.3％及92.8％，同时成活率也高达98.14％；GABA亦有较好的诱导效果，当GABA浓度为10^-5 mol·L^-1，附着率及变态率分别为86.9％及87.6％；L-DOPA能诱导西施舌眼点幼虫变态，当L-DOPA浓度为10^-6 mol·L^-1时，变态率达73.3％，附着率达84.9%. Ca²⁺最适宜浓度为20 mmol·L^-1时，附着率、变态率及成活率分别为86.1％、42.8％和87.4％。以上4种化合物最适宜浓度诱导作用时，西施舌幼虫的附着率和变态率均显著高于对照组。实验还对Ca²⁺在西施舌大规模人工育苗中的诱导作用进行探讨。     

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.