Failure of swim bladder inflation of perch,Perca fluviatilis L. found in natural populations

Perch suffering from swim bladder inflation failure (sinkers) are reported from wild populations of Lakes Constance, Geneva, Lucerne, Sempach, and Zurich in central Europe. Sinkers were found at all 7 locations considered in a survey. Relative abundance of sinkers varied from 0.1% to 7.9% of local perch populations. Sinkers from wild populations and sinkers reared in the laboratory showed similar behaviour and malformations. Information on sinker syndrome in 26 physoclistous species is compiled. It is found to be a widespread problem in aquaculture, but is reported here for the first time from natural populations.     

衡阳盆地始新世含鱼地层的成因分析

衡阳市郊五马归槽始新世鱼化石保存在黑色湖相纹层中。根据纹层序列的对比,发现该地的鱼化石均为同一层位;根据鱼化石在纹层序列中的具体位置及鱼化石的保存状况,笔者推测鱼群的死亡并非由于季节更替,而是由气候干旱引起的湖水盐度升高所控制;黑白纹层的变化是由大气降雨所致。     

Organochlorines and other environmental contaminants in muscle tissues of sportfish collected from San Francisco Bay

Edible fish species were collected from 13 locations throughout San Francisco Bay, during the spring of 1994, for determination of contaminant levels in muscle tissue. Species collected included white croaker, surfperch, leopard and brown smoothhound sharks, striped bass, white sturgeon and halibut. 66 composite tissue samples were analysed for the presence of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (P0CBs), pesticides, trace elements and dioxin/furans. The US EPA approach to assessing chemical contaminant data for fish tissue consumption was used for identifying the primary chemicals of concern. Six chemicals or chemical groups were found to exceed screening values (SVs) established using the US EPA approach. PCBs (as total Aroclors) exceeded the screening level of 3 ng g⁻¹ in all 66 muscle tissue samples, with the greatest concentrations (638 ng g⁻¹) found near San Francisco's industrial areas. Mercury was elevated (> 0.14 μg g⁻¹) in 40 of 66 samples with the greatest concentrations (1.26 μg g⁻¹) occurring in shark muscle tissues. Concentrations of the organochlorine pesticides dieldrin, total chlordane and total dichlorodiphenyltri-chloroethane (DDT) exceeded screening levels in a number of samples. Dioxin/furans (as toxic equivalent concentrations (TEQ's)) were elevated (> 0.15 pg g⁻¹) in 16 of the 19 samples analysed. Fish with high lipid content (croaker and surfperch) in their muscle tissue generally exhibited higher organic contaminant levels while fish with low lipid levels (halibut and shark) exhibited lower organic contaminant levels. Tissue samples taken from North Bay stations most often exhibited high levels of chemical contamination. The California Office of Health Hazard Assessment is currently evaluating the results of this study and has issued an interim Health Advisory concerning the human consumption of fish tissue from San Francisco Bay.     

串管海绵一新属——新瓜达卢佩海绵属(Neoguadalupia),兼论塞巴加斯海绵科各属间的关系

本文论述了云南广南董那孟下二叠统生物礁内的串管海绵化石,提出塞巴加斯海绵科具有三个明显演化分枝,这是它们对不同生态环境长期适应的结果。文章讨论了新属Neoguadalupia与相关属的区别,确立了在串管海绵演化史上的地位,并详细描述和讨论了Neoguadalupia elegana gen.et sp.nov.     

岩浆岩的熔点、粘度及其与化学成分的关系

本文研究了我国中、新生代一些岩浆岩的化学成分、熔点、人工玻璃的折射率和比重以及它们在不同温度下的粘度。在常压下岩石酸度愈大,熔点愈高。熔点与岩石的Fe~(2+(+Fe~(3+)+Mn+Mg±Ca为反相关;与Si+Al+K+Na为正相关。计算粘度与温度的关系表明,酸度愈大,粘度愈大;碱度愈大,粘度愈小,温度愈高,粘度愈低;同一温差下,酸度愈大,粘度变化愈大。     

浅变质岩石中的叠加韧性剪切带——以吉林桦甸二道甸子地区为例

吉林省桦甸市二道甸子金矿区的板岩、千枚岩中,存在着平行叠加式和垂直叠加式两个类型的韧性剪切带。它们叠加在早期变形构造之上,显示出不同的构造特征。前者以含“叶理鱼”的疙瘩状千枚岩为特征,“叶理鱼”的含量决定了其应变强度。后者以折劈构造成带状发育为特征,折劈的不同类型决定了其应变强度。     

Effects of larval density and salinity on the development of perch larvae (Perca fluviatilis L.)

We performed two experiments, one to test whether survival and initial swim bladder inflation of perchPerca fluviatilis are affected by population density (4 or 16 larvae 1^–1) or salinity (0, 0.6 and 1.2), and the second to test the salinity tolerance of larvae. In experiment 1, survival was higher at low larval densities and at salinities of 0.6 and 1.2 rather than in fresh water. Initial swim bladder inflation was not affected by salinity or density. Average survival of fry 24 days after hatching varied from 29.6% to 86.3%, but only an average of 19.2% of the hatched larvae had grown into viable fish with an inflated swim bladder. In experiment 2, survival varied from 19% to 49%, but was not significantly affected by salinities of up to 4.8. At a salinity of 9.6, only 2 out of 344 larvae survived.     

朝阳市建人工湖对地下水动力场影响及湖底铺设方案选择

朝阳市拟在城区段大凌河上兴建2个人工湖。本文利用地下水模型系统(Groundwater Modeling System，以下简称GMS)建立了地下水流动的数值模型，模拟了人工湖建成后在各种湖底渗透系数下地下水动力场的变化情况，并提出了人工湖湖底铺设应选取的合理有效的渗透系数为0．0432m/d。在此基础上，考虑到朝阳市经济社会的进一步发展对水资源量的需求，选取了采用聚氯乙烯膜(土工布)铺设湖底并预留原河道两侧占总湖底50％的面积以补给地下水的铺设方案作为最优方案，并在现有开采量的基础上增加了19600m^3／d的开采量。     

洮儿河扇形地修建地下水库可行性研究

利用大量实际资料,采用GMS软件建立了白城市洮儿河扇形地立体地质模型,系统研究了区域水文地质条件,应用Surfer软件,采用含水层体积法和水层厚度法计算了地下水库的储存空间,采用动态资料推求、野外试验和室内实验等多种方法确定了主要水文地质参数,重点分析计算了洮儿河扇形地作为地下水库的储水空间、补给水源和调蓄能力,讨论了在该区修建地下水库的可行性及其效果,提出扇形地地下水库设计与建设的有关建议。     

人工蚂蚁感知规律的研究

从分析自然蚂蚁行为出发，阐述了人工蚂蚁采用影像纹理能量作为自身信息素，通过信息素相似性度量，使其具有“识别”、“记忆”感知功能的原理和方法。通过大量实验分析了影响人工蚂蚁感知能力的因素，得到人工蚂蚁感知规律的一些认识，这些认识对蚁群行为仿真在图像解译中的应用有一定的指导价值。