七种捕食性鱼类对中华绒螯蟹幼蟹捕食风险的评估

分别以鲤、鳜、斑点叉尾、黄颡鱼、瓦氏黄颡鱼、大口鲇和乌鳢作为捕食者,以中华绒螯蟹幼蟹作为猎物,在室内水泥池(2.4 m3)进行捕食试验。以日捕获率和日摄食率为指标,评估这些鱼类对幼蟹的捕食作用和危害程度,为提高湖泊幼蟹放流效果、建立蟹—鱼复合的优质高效养殖模式提供科学依据。在幼蟹完全暴露的条件下,经过多次(至少9次)重复的试验(短期1d和长期7d),鳜对不同大小的硬壳和软壳(刚蜕壳的)幼蟹没有任何捕食作用;黄颡鱼对硬壳和软壳幼蟹也没有捕食作用,但还需做进一步观察;虽然鲤、瓦氏黄颡鱼对硬壳蟹的捕获率低,但对软壳的幼蟹有较大的危害性,对幼蟹的日摄食率分别为0.070%、0.012%;大口鲇、斑点叉尾、乌鳢对幼蟹具有较强的捕食能力,对幼蟹的日摄食率分别为0.122%、0.188%和0.284%。根据这些研究结果,可以建议:(1)在池塘和湖泊河蟹养殖中,完全可以将鳜作为套养或混养对象,以期提高养殖效益;(2)在河蟹放养的湖泊,需要抑制乌鳢和大口鲇种群,适当减少鲤和瓦氏黄颡鱼丰度,以期减少这些鱼类的捕食作用,提高幼蟹存活率;(3)在河蟹养殖池塘,不能放养乌鳢、大口鲇、斑点叉尾、瓦氏黄颡鱼和鲤

盈余持续性、审计师类型对盈余持续性的影响及资本市场反应

以我国2002~2008年期间A股上市公司为研究对象,延续Sloan的方法,利用mishkin检验来考察公司盈余持续性、审计师类型对盈余持续性的影响及股票市场反应。发现公司盈余中应计成分持续性低于现金流量成分;四大审计客户的盈余持续性要高于非四大审计的客户;与公司盈余中现金流量成分相比,四大审计师更显著提高公司盈余中应计成分的持续性;股票价格中所包含的公司盈余预期不能反映公司盈余中应计成分和现金流量成分持续性的差别;股票价格中包含的盈余预期可以总体上反映四大与非四大审计师对公司盈余持续性影响的差异,但股票价格中包含的盈余预期不能反映四大与非四大审计师对公司盈余中应计成分和现金流量成分持续性影响的不同,市场符合"幼稚投资者"假说

Other Spaces in Legal Pedagogy

There is an increasing focus upon the material and metaphoric spatial dimensions of various academic disciplines, including law. This essay considers the spatial dimensions of legal pedagogy, focusing on Critical Race Theory (CRT). The essay first explains the critical program in law and how CRT grows out of it. The essay then suggests that the critical program, and especially CRT, is as much a human geographic or spatial construct as it is a social, political or historic one, and briefly describes the nature of human geography and legal geography. It next considers how metaphors for understanding CRT\u27s position in legal pedagogy are found in some of Foucault\u27s work on geography. In Des Espaces Autres ( Other Spaces ), Foucault argues that there are three distinct social spaces in society: real spaces, utopias, and heterotopias. What unites them, Foucault suggests, is a space that includes elements of all of these spaces, a space that he calls the mirror. Applying this frame, this essay posits that CRT, both the explicit courses on the topic and the discipline itself, should be re-mapped , that is, barriers to its inclusion in the broader legal pedagogy should be eliminated. In this way, CRT can function as a Foucauldian mirror rather than a heterotopia in legal pedagogy

Global climate change and mangrove

通讯作者:郑文教[中文文摘]因为红树林位于海洋与陆地之间,其可能是首先被全球气候变化影响的生态系统。红树林的分布会随着温度气温的升高而增加。全球气候变化对红树林最重要的影响是海平面的变化。随着CO2的增多,大部分的红树林有高的光合作用率、水的利用效率以及生长率。在相对低的光照条件下,红树林的光合作用率相对较高。最后提出了今后尚待加强的一些研究领域。[英文文摘]Mangrove locates at the interface between land and sea, and is likely to be one of the first ecosystems to be affected by global climate change. Its distribution area would be enlarged with raising temperature. The most important effects of global climate change on it would be t he r ising sea levels. Most mangrov es w ill benefit from increased CO2 via hig her photosynthetic rate, water use efficiency , and growt h rate. At relatively low light level, the photosynthetic rate of mangroves tends to increase. The strategies to deal with these changes were put forward.国家自然科学基金资助项目(39370147

Comparison on karyotype of Minxiangli(Channa maculata♀×C. argus♂) and its parents

以闽香鳢及其亲本乌鳢和斑鳢为材料,取头肾做3种鱼的染色体组型图,发现闽香鳢染色体数为45,是亲本配子染色体数之和;通过染色体组型分析发现闽香鳢的染色体组型公式为2n=3m+6sm+36st,t,臂数NF=54,个别染色体可分辩出其来源。研究表明,闽香鳢遗传了其父本、母本各一套的染色体(n),是斑鳢与乌鳢的杂交种;染色体数和闽香鳢1号特异染色体可做为闽香鳢的鉴定指标。随机取样发现子一代闽香鳢存在性腺发育Ⅲ期以上的雌性个体,而未发现有性腺成熟的雄性个体,可能存在雄性不育。According to karyotype diagram of the first filial generation (Channa meculorta♀×C. argus♂) and their parents, the number of chromosomes in the first filial generation (called Minxiangli) is 45, which is equal to the sum of those in their parents gametid. Karyotype analysis turns out that the formula for karyotype of Minxiangli is 2n=3m+6sm+36st,t, NF=54, and that several chromosomes could be distinguished their origin. Therefore, it concludes that Minxiangli respectively inherits a suit of chromosomes from their parents, which is the hybrid of C. argus and C. meculorta, and that the number of chromosomes and the No.1 special chromosome of Minxiangli could become identification indexes of Minxiangli. In addition, it is found by random sample that there are female individuals in the first filial generation whose sex gland growth is beyond the third period, but no male individuals whose sex gland is mature. It may be deduced that the male individuals are sterile in the first filial generation.福建省科技厅(2002-50

武湖的渔业资源及渔业利用初步意见

武湖现有鱼类50种,其中鲤科鱼类33种,占总数的66%。渔获物组成中,鲢、鳙、鲤、鲫、鲌的产量占总产量的93%左右,渔获物以低龄为主。武湖目前的主要增养殖方式是放养鲢鳙,通过投放无机和有机化肥培养浮游生物来达到增加鲢鳙鱼产量的目的。针对武湖的渔业资源现状和渔业可持续发展的需要,提出了渔业利用的初步意见

柱前衍生化高效液相色谱法测定2-去氧葡萄糖的含量

目的建立柱前衍生化高效液相色谱法测定2-去氧葡萄糖(2-DG)含量的方法。方法采用1-苯基-3-甲基-5-吡唑酮(PMP)为柱前衍生化试剂,将2-DG在碱性条件下衍生化后直接进样测定。分离柱为HypersilODS2色谱柱(4.6 mm×250 mm,5μm),流动相为100 mmol·L-1醋酸铵缓冲液(pH 5.5)-乙腈(78∶22),流速1.0 mL·min-1,波长249 nm。结果 2-DG在19.68~393.6μg·mL-1浓度范围内与峰面积具有良好的线性关系(r=0.9997);其定量限(S/N=10)和最低检出限(S/N=3)分别为7.8和3.1 ng;平均回收率为101.21%,RSD 0.63%。结论该方法简便实用、检测灵敏度高、测定结果准确,适用于2-DG的质量控制

Bacterial community and its relation to environmental variables in a subtropical stratified reservoir for drinking water supply in autumn

水库在我国东南沿海地区是重要的饮用水水源地,对地区经济发展和社会稳定起到重要作用。选择亚热带地区典型的热分层水库——福建莆田东圳水库,于2011年秋季稳定分层期,以水体温度的垂直变化特征为依据进行分层采样。应用PCrdggE和克隆测序的方法研究浮游细菌群落的垂直分布特征,利用多元统计分析揭示细菌群落与热分层水体理化指标之间的关系。结果显示:溶解氧、电导率、叶绿素A、总氮、氨氮及硝氮在上下层水体中的分布有显著差异,下层缺氧区细菌的SHAnnOnWIEnEr指数和dggE条带数明显高于上层好氧区,表明东圳水库热分层水体中存在明显的物理、化学及生物分层现象。测序结果表明β-变形菌可能是东圳水库中占优势的细菌类群,统计结果提示溶解氧是显著影响细菌群落组成的环境因子。热分层水体的物理化学分层与水体细菌群落结构密切相关,提示水库生态学研究应对水体热分层给予重视。Fujian reservoirs in southeast China are important water resources for economic and social sustainable development,although few have been studied previously.Dongzhen Reservoir,a typical subtropical stratified reservoir in Fujian,was chosen for investigation of bacterial distribution,composition and diversity in autumn 2011.As the only built large reservoir in Putian City,it plays an important role in irrigation,flood control,hydroelectric power,and water supply.Dongzhen Reservoir shows an obvious phenomenon of water thermal stratification during summer and autumn,thus creates a unique gradient of environmental variables along the water column.We investigated the bacterial community and its relation to environmental variables in this study for a better understanding of vertical distribution of bacterial community and theprimary environmental drivers in a stratified reservoir.Five water samples were collected from five different depths according to the vertical changes of temperature.Both PCR-DGGE and sequencing were used to investigate the bacterial community and diversity.Moreover,physical and chemical parameters were measured according to the national standard methods.Multivariate statistical techniques were used to examine the relationship between bacterial community and environmental variables.Principal component analysis( PCA) clearly showed that water temperature,dissolved oxygen( DO),chlorophyll a( Chl a),total nitrogen( TN),ammonia nitrogen( NH4-N),nitrite / nitrate nitrogen( NOx-N) and electric conductivity of the upper aerobic zone were differed from those of the deeper anoxic zone.Both the number of DGGE bands and the Shannon-Wiener index of the deeper anoxic zone were higher than those of the upper aerobic zone.Further,two groups were distinguished by the cluster analysis of bacterial communities based on the Bray-Curtis similarity.Thus,Dongzhen Reservoir presented an obviously physical,chemical,and biological stratified phenomenon.Seven bands that common to all sampling depths were extracted and sequenced,and among which four were identified as Betaproteobacteria,indicating that Betaproteobacteria were the most dominant taxa in Dongzhen Reservoir in autumn.Bacterial community composition and diversity differed greatly among different sampling depths,and these differences were closely related to the physical and chemical stratification of the water body.Redundancy analysis( RDA) demonstrated DO was the significant environmental variable that shaping the bacterial community and diversity( P < 0.01).Therefore,we should pay more attention to DO and thermal stratification of reservoirs for sustainable reservoir management.国家重大科学研究计划(2012CB956103); 中国科学院知识创新工程方向项目(KZCX2-YW-QN401); 国家自然科学基金面上项目(31172114); 福建省杰出青年科学基金项目(2012J06009