四种理化因子对双齿许水蚤卵子孵化率的影响

研究了温度、盐度、pH、光照强度等理化因子对双齿许水蚤(Schmackeria dubin)孵化率的影响。结果表明,温度对双齿许水蚤的孵化率影响显著(P<0.05),其最适温度为30℃,孵化率达82.7%;盐度对双齿许水蚤的孵化率影响不显著(P>0.05),在盐度5~40的范围内均能正常孵化;pH对双齿许水蚤的孵化率影响显著(P<0.05),其适宜pH为6.5~8.5,孵化率达83.0%;光照强度对双齿许水蚤的孵化率影响显著(P<0.05),在照度为100 lx时其孵化率为69.1%,在1 000 lx时孵化率大幅度降低至8.8%,在4 000 lx以上时,其不能孵化甚至出现死亡。     

不同盐度对龙虎斑生长和摄食的影响

在盐度5、10、15、20、25、30条件下,以全人工配合饵料饲喂龙虎斑[鞍带石斑鱼(Epinephelus lanceolatus♂)×棕点石斑鱼(E.fuscoguttatus♀)]60 d,研究不同盐度对龙虎斑生长和摄食的影响。结果表明,不同盐度对龙虎斑生长的影响有统计学意义(P0.05),盐度5~20组增长率、特定生长率均高于盐度25、30组,差异有统计学意义(P0.05),盐度10组的增长率最高,为55.08%,盐度15组的特定生长率最大,为2.30%/d,盐度和龙虎斑生长速率的回归方程为K=0.000 09 S 4-0.006 S 3+0.131 S 2-1.055 S+4.832(R 2=0.984);不同盐度对龙虎斑的摄食率和饵料系数影响有统计学意义(P0.05),盐度15组的摄食率最高,为1.64%/d,其次为盐度10组,为1.60%/d,饵料系数在盐度15组最低,为0.820,其次为盐度10组,为0.827。因此,龙虎斑在低盐度条件下生长比高盐度快,摄食率高,饵料利用率高,最佳生长盐度为10~15。     

pH、亚硝酸盐和氨氮对双齿围沙蚕耗氧率和排氨率的影响

在实验室条件下研究不同pH(5.0、6.0、7.0、8.0、9.0)、亚硝酸盐浓度(0、0.036、0.357、0.714、1.429mmol/L)和氨氮浓度(0、0.036、0.357、0.714、1.429 mmol/L)对双齿围沙蚕(Perinereis aibuhitensis)耗氧率和排氨率的影响。结果表明,在不同p H条件下各组双齿围沙蚕的耗氧率差异无统计学意义(P0.05);pH为7.0时,沙蚕的排氨率较低(2.37±0.51μg·g~(-1)·h~(-1)),pH为9.0时,排氨率最低(0.44±0.13μg·g~(-1)·h~(-1))(P0.05)。随着亚硝酸盐氮浓度的升高,其耗氧率仅在0.714 mmol/L组升高,与其他各组差异无统计学意义(P0.05),而排氨率0.036 mmol/L组升高,之后急速下降,1.429 mmol/L组最低,差异有统计学意义(P0.05)。随氨氮浓度的增加,双齿围沙蚕耗氧率呈下降趋势,当氨氮浓度0.714~1.429 mmol/L时差异有统计学意义(P0.05)。     

温度和盐度对龙虎斑存活与摄食的影响

龙虎斑是由棕点石斑鱼(Epinephelusfuscoguttatus♀)和鞍带石斑鱼(Epinepheluslanceolatus♂)的杂交种。研究水温及盐度在骤变和渐变情况下龙虎斑的存活和摄食情况,结果表明:龙虎斑在温度为14³5℃的海水中均能存活和摄食,最适宜温度环境为2535℃的海水中均能存活和摄食,最适宜温度环境为25³5℃;温度从30℃骤变至20、25、35℃时,龙虎斑100%存活;从30℃骤变至10℃和15℃时,龙虎斑全部死亡;水温从30℃开始渐变,下降幅度为1℃/d,当下降至24℃时摄食减少,13℃时停止摄食,下降至11℃时出现死亡。龙虎斑在盐度为135℃;温度从30℃骤变至20、25、35℃时,龙虎斑100%存活;从30℃骤变至10℃和15℃时,龙虎斑全部死亡;水温从30℃开始渐变,下降幅度为1℃/d,当下降至24℃时摄食减少,13℃时停止摄食,下降至11℃时出现死亡。龙虎斑在盐度为1⁵5的海水中均能存活和摄食,摄食适宜海水盐度为455的海水中均能存活和摄食,摄食适宜海水盐度为4⁴5;盐度从30骤变至5、10、15、20、25、35、40、45、50、55等盐度时,龙虎斑100%存活,骤变至0时,4 h内存活率100%,16 h存活率55.5%;盐度从30渐变,每天降低2,降至6后,每天降低1,盐度降到1时,龙虎斑的活动和摄食明显减少,渐变至0时,36 h出现死亡,48 h内全部死亡。     

摄食水平对卵形鲳鲹幼鱼的生长和能量收支的影响

水温28±1℃条件下,投喂人工配合饲料,研究摄食水平1%、2%、3%、4%、5%(每日投喂量占初始实验鱼湿重的质量百分比)及饱食对卵形鲳鲹幼鱼(初始体重5.77±0.45g)生长及能量收支的影响。结果表明,卵形鲳鲹幼鱼特定生长率、转化效率、摄食率随着摄食水平的提高而增长,摄食水平达4%时干重特定生长率与饱食组差异无显著性(P>0.05),摄食水平达5%时,湿重、蛋白质和能量生长率与饱食组差异无显著性(P>0.05);摄食水平达4%时能值转化效率与饱食组差异无显著性(P>0.05),摄食水平达5%时,干重、蛋白质转化效率与饱食组差异无显著性(P>0.05);摄食水平达2%时干重、蛋白质表观效率与饱食组差异无显著性(P>0.05),摄食水平达4%时,能量表观效率与饱食组差异无显著性(P>0.05)。生长能分配率随摄食水平升高而显著增加(P<0.05),代谢能、排粪能及排泄能分配率的变化则相反。建立了6种摄食水平条件下卵形鲳鲹幼鱼的能量收支方程。     

盐度、pH和规格对尖紫蛤滤水率、摄食率、吸收率的影响

采用室内实验生态学方法对尖紫蛤的滤水率、摄食率和吸收率进行了研究。结果表明,盐度为2~18时,3种规格尖紫蛤的滤水率和摄食率先升后降,在盐度10.50~12.10内滤水率和摄食率出现最大值,最佳摄食盐度为11.41~12.10;pH在6.4~9.4时,3种规格尖紫蛤的滤水率和摄食率先升后降,在pH为8.23~8.45内滤水率和摄食率出现最大值,尖紫蛤最佳摄食的pH为8.23~8.28。尖紫蛤的吸收率与盐度的相关性不大。     

台风“彩虹”对粤西近岸海表温度和叶绿素浓度的影响

利用高分辨率的海表面温度(SST)和叶绿素a浓度数据,分析2015年超强台风"彩虹"对粤西近岸海洋动力环境的影响。结果表明:"彩虹"过境后,粤西海域SST总变化为降温,且台风路径右侧降温高于左侧,最大热损失达到-9×10~6 J/m~3。"彩虹"引起的降温幅度以及最大降温出现时间在不同海区有所不同。珠江口附近海域、珠江口外海200 m等深线附近以及阳江至东海岛沿岸区域在台风登陆后2―4 d形成3个降温中心,最大降温均为-2℃左右。对台风路径两侧近岸、陆架和深水六个区域对比分析发现,近岸SST变化幅度最大,且两侧最大降温时间相同,而陆架和深水区则是左侧降温低于右侧。台风路径左侧雷州半岛以东约100 km和海南岛以东近海的叶绿素a浓度显著增加,最大增幅达5 mg/m~3。     

Ⅰ、激素的适宜种类和浓度对海水单胞藻生长的影响

选择了三类六种植物激素，试验了五种常用于鱼、虾、贝的活饵料——海水单细胞藻，证明了增产素、乙烯利对亚心形扁藻和钙质角毛藻的生长有增效作用。以10—50ppm增产素处理亚心形扁藻的净增产率为40—70％，并对细胞大小产生影响，它的细胞长度增加3-14％，宽度增加4—7％。     

高阶电离层延迟对GPS双差观测值和基线向量的影响

用RINEX HO软件计算GPS载波相位观测值中的高阶(二阶和三阶)电离层延迟,在此基础上组成GPS双差观测值中的高阶电离层延迟(ΔI_H)^p,q_i,g。讨论了(ΔI_H)^p,q_i,g与地磁纬度、基线长度、基线方向及太阳活动水平间的关系。在其他条件均相同的情况下,用Bernese 5.0软件分别对进行了高阶电离层延迟改正的观测值和未进行高阶电离层延迟改正的观测值进行基线解算,求得高阶电离层延迟对基线向量解的影响Δb_H。结果表明,Δb_H的数值很小,在一般情况下可忽略不计。ΔbH与基线长度及太阳活动水平等因素间并无必然联系,但随着时段的减小,Δb_H会随之增大。     

Effects of calanoid copepod Schmackeria poplesia as a live food on the growth, survival and fatty acid composition of larvae and juveniles of Japanese flounder, Paralichthys olivaceus

Zooplankton constitutes a major part of the diet for fish larvae in the marine food web, and it is generally believed that copepods can meet the nutritional requirements of fish larvae. In this study, calanoid copepod Schmackeria poplesia, rotifer Brachionus plicatilis and anostraca crustacean Artemia sp. were analyzed for fatty acid contents, and were used as live food for culturing larval Japanese flounder, Paralichthys olivaceus. The total content of three types of HUFAs (DHA, EPA and ARA) in S. poplesia was significantly higher than that in the other two live foods (P<0.01). Three live organisms were used for raising larvae and juveniles of Paralichthys olivaceus respectively for 15 and 10 d. Then the growth, survival and fatty acid composition of the larvae and juveniles were investigated. The results showed that the larvae and juveniles fed with copepods (S. poplesia) had significantly higher growth rate than those fed with the other two organisms (P<0.01). The survival of the flounder larvae fed with copepods was significantly higher than that of the others (P<0.01), and the survival of the juvenile fish fed with copepods was higher than that fed with Artemia (P<0.05). The contents of three types of HUFAs (DHA, EPA and ARA) and the ratio of DHA/EPA in larval and juvenile flounder P. olivaceus were analyzed. The results showed that the contents of DHA, EPA and ARA in the larvae and juveniles fed with S. poplesia were higher than those fed with a mixed diet or Artemia only, and the ratio of EPA/ARA in larvae and juveniles of P. olivaceus fed with S. poplesia was lower than that in the case of feeding with a mixed diet or Artemia only. The present data showed that copepod is the best choice for feeding the larvae and juveniles of fish considering its effects on the survival, growth and nutrition composition of the fish.     

北京市人口密度空间分布及其尺度特性研究

利用北京市第六次人口普查数据,在对人口统计数据进行空间化处理的基础上,分析了城市人口密度分布的统计特征及其空间自相关性,充分证明了北京市人口密度分布具有非常强烈的空间自相关性,并已经凸显出城市人口密度多核心分布模型的特征;在对人口统计数据进行格网化处理的基础上,分析了6种不同尺度下北京市人口密度空间分布的统计学特性和空间自相关性,证明了北京市人口密度的空间分布具有尺度特性;本文进一步对尺度特性影响下的人口密度空间分布特性空间自相关性进行了对比研究,从而揭示出空间自相关性与尺度变化间的规律。     

Water Intake and Utilization in Mithun (Bos frontalis):Effect of Environmental Temperature, Rearing System and Concentrate Feed Supplement

Seasonal and sexual variations as well as the effect of dry feed supplement on total drinking water intake and its utilization were observed in mithun (Bos frontalis)-a semi-wild animal found in North Eastern Hill Region (NEHR) of India. In a completely randomized design, twelve adult mithuns (B. frontalis) as per their sex and body weight were assigned in two different rearing systems (free grazing and free grazing with dry concentrate feed supplementation), and ten growing male mithuns as per their body weight assigned in two different levels of dry concentrate feed supplementation (1.0 kg and 2.0 kg dry concentrate feeds on green forage based diet) and in two different seasons (summer and winter). It was observed that the environmental temperature had a significant effect on drinking water intake by mithuns. Drinking water consumption (per unit of body weight) was significantly (P < 0.05) higher in summer than in winter. Supplementation of concentrate feed on free grazing animals resulted in increase in water consumption. Total water consumption (drinking as well as performed water) was found to be 15.18 litres per 100 kg body weight by growing mithun. Feed dry matter and digestible nutrient intakes by growing mithun were observed to be increased with the increase of supplementation of dry concentrate feed. Roughage to concentrate ratio did not affect the nutrient digestibility. Mithun calves drank an average of 4.30 litres water for each kg of dry matter intake. Metabolic water was significantly (P<0.01) increased with the increase of supplementation of concentrate feed whereas water turn over, which depends upon the body weight of the animals, did not differ significantly on offering of lower or higher level of dry feed. Faecal water loss of growing mithun was decreased with the increase in intake of concentrate feed and was estimated to be 33～46% of total water intake. Excretion of water through faeces of mithun was about 3.8% of body weight. It could, therefore, be inferred that water intake by mithun varied with seasons, rearing systems and dry feed consumption. As far as the water nutrition is concerned, it is needed to give an attention while feeding mithun in summer with dry feed supplementation under semi-intensive system of rearing.     

基岩露头采样密度对黄土古地形重建的影响

下伏古地形对黄土地貌的形成、演化与发育具有重要的控制作用。基于下伏地层露头的采样数据,通过空间插值方法进行古地形数字模型(DEM)重建是研究黄土地貌的重要方法。其中,采样点密度是下伏地形DEM重建精度的主要影响因子。本文以1:20万绥德幅地质图所涉及区域为实验样区,研究采样点密度及样条函数方法对下伏古地形重建精度的影响。实验结果表明,在高密度样本条件下,采用规则样条插值方法进行古地形重建时,插值结果呈现显著的“龙格现象”,即多项式插值结果出现剧烈波动现象,且随着样本密度增加,样条插值结果的误差呈逐步趋缓的降低趋势,并逐步趋于稳定。同时,基于古地形DEM提取的特征点,其局部最高点和局部最低点的数目呈直线上升趋势,说明在一定程度上基于有限数据采用样条函数进行地下三维建模并不一定能获得平滑曲面。研究结果对如何选择合理的空间采样密度进行古地形DEM重建具有重要的指导意义。     

Ingestion of Domoic Acid and Its Impact on King Scallop（Pecten maximus,Linnaeus 1758）

A simple method for spiking formulated feed with domoic acid （DA） was developed in this study. DA feed was prepared by mixing 0.15 mL 100 μg mL-1 DA with 0.1 g formulated feed, and drying the mixture at room temperature for 2 h. The prepared DA feed contained 0.19 pg DA per particle. Of the added DA, 46.72% was retained in the feed. Relatively high DA retention （about 50%） was recorded after DA feed was soaked in water for 2h. Exposure to DA feed for 7d did not cause the increase of tissue DA level of adult king scallop （Pecten maximus） significantly in 60 d. The increase of their gonad index after DA exposure was not significantly different from the control. No significant change in DA level was found in spermary, ovary or fertilized eggs after DA exposure. These results indicated that DA excretion may be more efficient than DA accumulation under the current experimental conditions, and the mechanism of domoic acid incorporation in P. maximus may involve intracellular biotransformation.     

北天山地区近期重力场及地壳密度变化特征研究

利用2014～2019年北天山地区流动重力资料,采用绝对重力控制进行经典平差计算,获取该地区重力场时空演化特征图像,并结合重力段差可视化方法,得到该地区重点构造部位物质迁移规律.采用紧凑反演方法进行北天山中段不同深度地壳密度模拟计算,结果表明,北天山中段地壳物质密度变化最佳深度为30～40 km,是地壳密度变化的正值区...     

土的天然密度对地表地震动参数的影响

选择3种不同强度的人造地震动加速度时程作为基岩地震动输入,采用一维土层频域等效线性化波动方法进行土层地震反应分析,研究两种不同土性的土层剖面,在一定范围内土的天然密度变化对场地地表地震动参数的影响,分析了峰值加速度和反应谱特征周期的变化趋势。结果表明,地表峰值加速度与土层的天然密度存在负相关关系,土体的天然密度增大,地震动峰值加速度逐渐减小。地表加速度反应谱特征周期与土体密度的变化相关关系不明显。     

Effect of bis(tributyltin) oxide on reproduction and population growth rate of calanoid copepod Schmackeria poplesia

A full life-cycle toxicity test, combined with histology, on calanoid copepod Schmackeria poplesia was used to study the effect of bis(tributyltin) oxide (TBTO). The results indicate no sex-specific differences in TBTO toxicity. Long-term mortalities of the copepods exposed to concentrations higher than 20 ng TBTO L⁻¹ were significantly elevated compared with that of control, and larval development was inhibited when they were exposed to 40 and 60 ng TBTO L⁻¹. The percentages of ovigerous females were reduced compared with the control (P<0.01) after 24 days exposure to concentrations higher than 10 ng TBTO L⁻¹. Histological examinations suggest that exposure to TBTO might block the posterior end of the diverticula and inhibits the production of egg sacs. A modified Euler-Lotka equation was used to calculate a population-level endpoint, the intrinsic rate of natural increase (r _m), from individual life-table endpoints, i.e. mortality rate, time of release of first brood, sex ratio, the fraction of ovigerous females among all females as well as the number of nauplii per ovigerous female. Apart from the highest TBTO concentration (60 ng L⁻¹), where all females aborted their egg sacs, 20 ng TBTO L⁻¹ was the only concentration that significantly decreased r _m compared with that of control (an effect associated with decreased sex ratio). The results show that the S. poplesia is affected by prolonged exposure to low concentrations of TBTO. The full life-cycle toxicity test combined with histology experiments provides more integral understanding of the toxicity of endocrine disrupters.     

温度对奥尼罗非鱼仔稚鱼生长、饲料利用和消化酶活力的影响

研究了温度22、25、28、31和34℃下奥尼罗非鱼(Oreochromis niloticus×O.aureus)仔稚鱼生长、饲料利用和消化酶活力。结果表明:1)不同温度对奥尼罗非鱼仔稚鱼生长有显著影响(P<0.05),温度为31℃时,仔稚鱼生长速度和绝对增重率最高,分别为0.08cm/d和0.035g/d;温度为22℃时最低,仅0.06cm/d和0.020g/d。2)饲料系数在28℃时最低,仅1.90;22和34℃时较高,达2.14和2.17,各组差异显著(P<0.05)。3)在仔稚鱼发育和存活率上,当温度在22～34℃时,温度越高,仔稚鱼发育越好;各组仔稚鱼的存活率介于93.7%～94.7%,差异不显著(P>0.05)。4)在消化酶活力上,胃蛋白酶、胰蛋白酶和淀粉酶活力随温度升高而升高,均在34℃时活力最高;脂肪酶活力在31℃时达到最高,22℃时活力最低。