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1.
洪湖日本沼虾的种群繁殖生物学   总被引:6,自引:0,他引:6  
1994年5月至1995年6月对洪湖日本沼虾的种群繁殖生物学进行了研究.洪湖日本沼虾的繁殖期为4月中旬至10月上旬,5月中旬至8月中旬为日本沼虾的繁殖高峰期,其中6月、8月雌虾抱卵率均在70%以上;日本沼虾群体中雄性总是少于雌性,月性比(♀/♂)变化于1.104-5.780之间,3—6月性比逐渐增高,7─10月性比则逐渐降低;在整个繁殖期.4─7月的抱卵虾均为前一年出生的大、中规格的个体,之后当年出生的个体在繁殖群体中逐渐占据优势;春季抱卵虾的绝对繁殖力和相对繁殖力都大于秋季抱卵虾,分别计算了绝对繁殖力、相对繁殖力与体长、体重的函数关系.本文还对日本沼虾群体性比的周年变化及其产卵次数进行了讨论.  相似文献   

2.
新疆艾比湖卤虫休眠卵发育的温度因子分析   总被引:4,自引:0,他引:4  
在不同的温度下对新疆艾比湖卤虫休眠卵进行了孵化试验 ,研究了卤虫发育速度与温度之间的关系 ,提出了相应的数学模型 ;V(T) =(k·T +c)·(1-exp(- (T -TH) /rH) ) ;并以此求算了该种群休眠卵孵化的最低临界温度为 5 .5 6℃ ,平均临界温度为 5 .96℃ ,最低有效积温为 342 .4 7℃×h ,平均有效积温为 4 13.6 3℃×h ;同时还就最适温度、耐温上限比较了高能卵与均能卵在适温能力上的差异 ,并最后讨论了这些参数在集约化养殖中的实践意义 .  相似文献   

3.
洪湖日本沼虾的种群繁殖生物学   总被引:4,自引:0,他引:4  
1994年5月至1995年6月对洪湖日本沼虾的种群繁殖生物学进行了研究。洪湖日本沼虾的繁殖期为4月中旬至10月上旬,5月中旬至8月中旬为日本沼虾的繁殖高峰期,其中6月、8月雌虾抱卵率均在70%以上;日本 虾群体中雄性总是少于雌性,月性比(♀/♂)变化于1.104-5.780之间,3-6月性比逐渐增高,7-10月性比则逐渐降低;在整个繁殖期,4-7月的抱卵是均为前一年出生的大、中规格的个体,之后当年  相似文献   

4.
湖北武湖日本沼虾的生长特性   总被引:13,自引:0,他引:13  
从1998年9月至1999年9月对人工养殖湖泊——武湖日本沼虾生长特性作了研究. 以月龄来研究日本沼虾的生长,研究结果表明日本沼虾在7-1月份(1-7月龄)呈等速生长,在2-6月份(8-12月龄)呈异速生长.日本沼虾体重(W)与体长(L)呈幂函数相关,但在7-1月份时其b值接近于3,而在2-6月份时其b值明显小于3,其关系式如下: 1-7月龄:W♂=0. 0148L3. 2419(r=0. 9978,n=390),W♀=0. 0206L3. 0117(r=0. 9968,n=372); 8-12月龄:W♂=0. 0857L2. 1788(r=0.9854,n=188),W♀=0. 1450L1. 8165(r=0. 9974,n=278). 1-7月龄雄虾的生长规律符合Von Bertalanffy方程,雌虾的生长规律符合Logistic方程;8-12月龄雌雄虾的生长规律都符合Logistic方程.  相似文献   

5.
发头裸腹溞休眠卵发育的温度因子分析   总被引:2,自引:0,他引:2  
测定了不同温度下发头裸腹溞(Moina irrasa)体眠卵的孵化时间及孵化率;取最先孵出和过半数孵出的两组数据依莱奥姆积温法则求得种群休眠卵最低临界温度为12.00℃,最低有效积温为441.61℃·h;最低亚致死高温点(即最适温度)为35.16℃,以及最低死亡高温点39.44℃。种群中过半数的临界温度为12.88℃,过半数有效积温为557.10℃·h,过半数的亚致死高温点为35.56℃以及过半数死亡高温点为39.49℃。讨论了这些参数在枝角类集约化培养中休眠卵的有效保存与启用所具有的实践意义。  相似文献   

6.
发头裸腹溞休眠卵发育的温度因子分析   总被引:2,自引:0,他引:2  
测定了不同温度下发头裸腹溞(Moina irrasa)体眠卵的孵化时间及孵化率;取最先孵出和过半数孵出的两组数据依莱奥姆积温法则求得种群休眠卵最低临界温度为12.00℃,最低有效积温为441.61℃·h;最低亚致死高温点(即最适温度)为35.16℃,以及最低死亡高温点39.44℃。种群中过半数的临界温度为12.88℃,过半数有效积温为557.10℃·h,过半数的亚致死高温点为35.56℃以及过半数死亡高温点为39.49℃。讨论了这些参数在枝角类集约化培养中休眠卵的有效保存与启用所具有的实践意义。  相似文献   

7.
The characteristics of high-latitude planetary waves (PWs) in the troposphere and lower stratosphere (TLS) are studied by using the data from radiosonde observations during 1998 to 2006 at three Alaskan stations in USA (Nome, 64.50°N, 165.43°W; McGrath, 62.97°N, 155.62°W; Fairbanks, 64.82°N, 147.87°W). It is found that strong PWs exist in two regions. One is around tropopause, and the other is in the polar night jet (PNJ) in winter. The PW activities are rather intermittent, and their lifetimes are no longe...  相似文献   

8.
全球大洋混合层深度的计算及其时空变化特征分析   总被引:5,自引:0,他引:5       下载免费PDF全文
本文利用2005-2009年的全球网格化Argo数据,分别采用温度判据和密度判据计算了全球大洋混合层深度(Mixed Layer Depth, MLD),讨论了障碍层(Barrier Layer, BL)和补偿层(Compensated Layer, CL)对混合层深度计算的影响,得到了合成的混合层深度,并研究了其时空变化特征. 研究表明:(1)在赤道西太平洋(10°S -5°N,150°E-150°W),孟加拉湾,热带西大西洋(10°N-20°N,30°W-60°W)是障碍层高发区域. 冬季的北太平洋副热带区域(30°N附近)以及东北大西洋(40°N-60°N,0°-30°W)是补偿层发生的区域. (2) 在各个半球的夏季MLD都比较浅,在各个半球的冬季MLD则普遍比较深. 北太平洋和北大西洋的MLD的分布和变化比较相似,印度洋MLD受季风影响显著,呈现半年周期变化. 太平洋和大西洋的MLD 的经向分布大致呈现出"两端深,中间浅"的拱形特点. (3)混合层深度距平场EOF第一模态时间变化为周期的年信号,北太平洋和北大西洋、南大洋(尤其是南极绕流区)都是MLD变化剧烈的海域,第二模态显示全球大洋混合层深度距平存在着一个半年的变化周期.  相似文献   

9.
The water exchange between the subpolar and subtropical gyres of the North Pacific is demonstrated by the simulation of chlorofluorocarbon (CFC) using an ocean general circulation model. The simulated CFC concentration in the North Pacific is in good agreement with observations. The water exchange is clearly illustrated by the tongues of CFC concentration. The subpolar waters with high CFC are transported southward into the eastern subtropical gyre, whereas the subtropical waters with low CFC are transported northward into the western subpolar gyre. The simulated exchange transport along 42°N in the layer of σθ< 26.8 indicates that the northward mass transport is about 15 Sv (1 Sv = 106 m3·s-1) west of 165°E, and about 5 Sv between 175°W and 150°W. The southward mass transport is about 5 Sv between 165°E and 175°W, and about 2 Sv east of 150°W.  相似文献   

10.
水丰水库亚洲公鱼和大银鱼种群生态的比较研究   总被引:4,自引:0,他引:4  
1998年 10月至 2 0 0 0年 11月对水丰水库亚洲公鱼和大银鱼的食性、生长、繁殖、群体结构进行了比较研究 .亚洲公鱼为杂食性鱼类但主要以浮游动物为食 ,繁殖时还摄食同类卵 ,出现频率达 4 2 .9% ,在冬季也摄食大银鱼卵 (2 .8% ) ;体长 (L)、体重 (W)呈异速生长 (W =1.176×10 - 6 L3.5555) ;群体繁殖速度比 1984年以前提高了 4 9.2 % ;群体结构中体长、体重的离散度很小 .大银鱼前期主要以浮游动物为食 ,后期以小鱼小虾为主要食物 ,也捕食公鱼 ,出现频率 6 .9% -9 6 % ;体长、体重呈等速生长 ,W =4 .4 82× 10 - 6 L3.0 0 0 9;群体繁殖速度高出公鱼 1.18倍 ;群体结构中体长、体重的离散度较大 ,表现出了个体间的差异性  相似文献   

11.
陆水水库的浮游生物及营养类型   总被引:7,自引:2,他引:7  
报道了1991 ̄1995年对面积为1693hm^2的黑龙滩水库渔业利用优化模式研究的结果,主要内容有:水生生物种类组成和现存量调查、浮游植物初级生产力测定、渔获物统计和鱼产力估算;水体理化性状和水位变化对鱼产量和浮游生物群落结构的影响,网箱养殖鲤、草鱼的高产试验结果;多功能水库生态系统的渔业利用优化模式初步探讨。经三年努力,水库鱼产量由622t上升到1255.1t,平均单产750kg/hm^2。为  相似文献   

12.
This study is designed to determine ammonia and nitrite excretion by Penaeus monodon 25–30 day old postlarvae fed with different diets (artificial and natural). Shrimps were fed with Chaetoceros calcitrans (phytoplankton), chironomid larvae (benthos), Brachionus sp. (rotifer) and artificial diet. In the control treatment, shrimps were not fed. The highest concentration of ammonia was excreted by shrimps fed with artificial diet and the lowest by that of control treatment. All treatments except where shrimps fed on C. calcitrans showed a sudden increase in ammonia-N excretion after 36 h. C. calcitrans contributed to high ammonia excretion only after 61 h. Shrimps fed with Brachionus sp. (rotifer) showed significantly higher nitrite excretion rate compared to other treatments. Shrimps fed on C. calcitrans depicted the lowest nitrite excretion. This experiment indicated that nitrogenous excretion was predominant in shrimps fed with artificial diets. Live food like algae and chironomids, despite a high protein content, contribute to low nitrogenous excretion and hence pose less adverse effects on water quality compared to artificial diets.  相似文献   

13.
密度和温度对萼花臂尾轮虫产卵量和混交雌体的影响   总被引:15,自引:1,他引:15  
杨家新  黄祥飞 《湖泊科学》1996,8(4):367-372
用小球藻(Chlorella sp.)为食培养萼花臂尾轮虫(Brachionus calyciflorus),食物浓度约1×10~6cells/mL,温度25℃,光照强度约40001x,昼长比LD=18:6。在1.0mL、0.5mL和0.25mL培养液中同时进行单个体和群体培养。结果发现:1)单个体培养时每个母体平均产卵量分别为12.0,13.8和7.8个;后代个体中混交雌体的百分比分别是46.38%,53.49%和55.83%。2)群体培养时,每个母体平均产卵量分别为8.7、3.1和2.65个,随密度增加而减少;后代个体中混交雌体百分比分别为41.70%,53.59%和54.26%,群体培养的密度为4.0ind./mL与2.0ind./mL,2.0ind./mL与1.0ind./mL混交雌体的百分比差异不明显。母体密度高低与后代混交雌体百分比间具有明显相关性。在上述培养条件下,轮虫为1.0ind./mL时,进行单个体培养,分别用急剧冷休克(SS)、逐渐冷休克(GS)和恒温对照(C)进行处理,结果表明:个体平均产卵量分别为10.8、9.2和12.6个。后代混交雌体百分比分别为32.85、20.7和16.87,SS和C处间后其混交雌体比例具显著差异,而SS和GS,GS和C处理间没有显著差异。  相似文献   

14.
In a novel biomanipulation experiment salmonids were used as a tool to improve water quality. The manipulation was initiated in spring 2000 as a response to non-point sources of phosphorus in a drinking water reservoir in Saxony, Germany. Salmonids (brown trout, Salmo trutta forma lacustris) were chosen as predators as the reservoir has a large hypolimnic water body and surface temperatures rarely exceed 20 °C. The vertical distributions of prey fish and brown trout were analysed with a fleet of vertical gill nets set in the pelagic zone of the reservoir. Consumption of brown trout was estimated by means of a bioenergetic model and the diet analyses of the trout. While the dominant planktivore (roach, Rutilus rutilus) was caught almost exclusively in the epilimnion during the stratification period trout were caught mainly below a depth of 10 m. Diet analysis revealed that the trout performed vertical migrations to consume food in the epilimnic layer, as an important food component were adult terrestrial and aquatic insects. The amount of fish in the food increased strongly with the size of the brown trout. The consumption estimate suggested that the trout had consumed 2-3% of the total roach stock during the study period (May-November 2000) of the first year of biomanipulation. We conclude that in general salmonids are suitable for food-web manipulation in deep reservoirs, but the stocked fish should be as large as possible (> 300 mm) and the proportion of large trout (> 500 mm) should be as high as possible.  相似文献   

15.
The Study of Two Geomagnetic Jerks in China   总被引:1,自引:0,他引:1  
This paper analyzes the first differences of the annual means (annual rate) for the Y and Z components of the geomagnetic field from nine magnetic observatories in China, measured from 1985 to 2003. The 1991 jerk was obvious in the Y component measured but not clear for the Z component. Rapid changes in the Z components were ubiquitous around 2000 -2001, but not seen for the Y component. External effects were removed from the monthly means by comparing the monthly mean of the geomagnetic field components at the observatories with the monthly time series of the Ap geomagnetic index. However, some examples were analyzed and showed whether external effects were removed or not, there was no marked distinction in determining the jerks in China for the Y component and the Z component of the geomagnetic field. Finally, the isolines of the first differences of the annual means were used to analyze the spatial and temporal distributions of the jerks.  相似文献   

16.
青虾生长规律与群体组成的研究   总被引:10,自引:3,他引:10  
报道了上海川沙县孙桥河道青虾的生长呈明显的阶段性,如雄虾的第一阶段(1990年6—11月)的生长方程为L_t=3.38[1-e~(-0.4943(t+0.1674)];第二阶段(1991年2—6月)的生长方程为L_t=6.57/(1+e~(2.1805-0.2787t);它们的拐点分别为2.07月龄和11.97月龄。渔获群体分析结果表明,月龄为0-15月,体长范围为1.30—6.58cm,体重范围为0.060—13.39g;一年出现两个群体,其中夏季群体生活期从当年7月至翌年10月,数量大,占群体数量80%以上;秋季群体生活期从当年9月至翌年12月,约占群体数量20%左右。群体中一般雄虾数量多于雌虾数量,月性比(?)在0.61—1.35之间变动。  相似文献   

17.
Bair ES  Metheny MA 《Ground water》2002,40(6):657-668
Remediation of ground water and soil contamination at the Wells G & H Superfund Site, Woburn, Massachusetts, uses technologies that reflect differences in hydrogeologic settings, concentrations of volatile organic compounds (VOCs), and costs of treatment. The poorly permeable glacial materials that overlie fractured bedrock at the W.R. Grace property necessitate use of closely spaced recovery wells. Contaminated ground water is treated with hydrogen peroxide and ultraviolet (UV) oxidation. At UniFirst, a deep well completed in fractured bedrock removes contaminated ground water, which is treated by hydrogen peroxide, UV oxidation, and granular activated carbon (GAC). The remediation system at Wildwood integrates air sparging, soil-vapor extraction, and ground water pumping. Air stripping and GAC are used to treat contaminated water; GAC is used to treat contaminated air. New England Plastics (NEP) uses air sparging and soil-vapor extraction to remove VOCs from the unsaturated zone and shallow ground water. Contaminated air and water are treated using separate GAC systems. After nine years of operation at W.R. Grace and UniFirst, 30 and 786 kg, respectively, of VOCs have been removed. In three years of operation, 866 kg of VOCs have been removed at Wildwood. In 15 months of operation, 36 kg of VOCs were removed at NEP. Characterization work continues at the Olympia Nominee Trust, Whitney Barrel, Murphy Waste Oil, and Aberjona Auto Parts properties. Risk assessments are being finalized that address heavy metals in the floodplain sediments along the Aberjona River that are mobilized from the Industri-Plex Superfund Site located a few miles upstream.  相似文献   

18.
太湖贡湖湾虾类种类组成与时空分布特征   总被引:3,自引:1,他引:2  
温周瑞  谢平  徐军 《湖泊科学》2011,23(6):961-966
分别于2005年4月、7月、10月利用蹦网对贡湖湾虾类种类组成和时空分布进行调查.共采集到虾类9605尾,属于2科3属5种,分别是秀丽白虾(Exopalaemon modestus)、日本沼虾(Macrobrachium nipponense)、锯齿新米虾中华亚种(Neocaridina denticulata sin...  相似文献   

19.
利用云鹏水电站周边5个数字地震台站记录到的2000年1月至2008年12月间的108个地震的数字波形资料,采用Aki单次散射模型,计算了各台站周围423条地震记录的尾波Q0值。结果显示:云鹏水电站地区尾波的Qc值与频率的关系为Qc(f)=90.2f0.94。该地区的Q0值比云南其它构造活动强烈地区的要高,因此属于中等构造活动地区。云鹏水电站蓄水后弥勒台记录到的108个地震的尾波Q0值及分频Qc值有所下降,但下降幅度不大,表明水库蓄水对库区及其附近区域地下介质性质有所影响,但影响的程度有限。  相似文献   

20.
2000年Jerk存在吗   总被引:2,自引:0,他引:2  
从分布在欧亚美太平洋几个质量较好的台站的dY/dt变化曲线看,2000年或2001年似乎没出现新的Jerk(Y)。  相似文献   

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