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1.
太湖鲫鱼数量变化的规律及与环境间关系的分析 总被引：6，自引：1，他引：5
通过食物组成分析和渔获物组成调查,并结合历年渔获量统计和环境监测资料,研究了太湖鲫鱼数量变化的规律、机制及与环境间的相互关系.渔获物调查和渔获量统计资料均表明:近年鲫鱼数量不断增加,已成为太湖仅次于鲚鱼的重要鱼类2004年渔获物调查中,鲫鱼占鱼类总重量的8.40%±2.69%,占鲤、鲫鱼渔获量的65.08%±15.47%;历年渔获量统计显示,1952-1998年鲤、鲫鱼渔获量相对稳定在1010.1±367.2 t、占鱼类总量8.89%±5.33%,1999年上升达到2547.4 t、占9.45%,2000年达到3708.7 t,占12.18%;年龄组成分析表明,鲫鱼低龄化趋势在加剧.食性分析表明:在7-12月,微囊藻占鲫鱼食物体积的83.65%-93.99%.分析认为:太湖鲫鱼以微囊藻为主要食物;富营养化加重为其提供了充足饵料,实施禁渔期、禁渔区等措施使其繁殖得到保障,捕捞强度过高导致其年龄组成低龄化、个体小型化.而太湖鲫鱼以蓝藻为主要食物,可能对蓝藻有抑制作用. 相似文献
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3.
对湖北省阳新县网湖所采得的862尾似刺鳊鮈的年龄与生长的研究表明,其年轮特征主要为切割型和碎裂型。其体长与鳞径呈直线相关:L=5.6784+4.3056R;体长与体重呈幂函数的增长关系:W=2.8026×10~(-2)L~(2.8754)。应用Van Bertalanffy生长方程拟合该鱼的一般生长规律,其生长参数为:L_∞=25.0143cm,W_∞=277.8876g,K=0.4668,t_0=-1.3886,拐点年龄t_i=1龄,拐点体长L_i=16.42cm,拐点体重W_i=82.82g。 相似文献
4.
铜绿微囊藻(Microcystic aeruginosa var. major)胞外酸性多糖的分离、纯化及其理化特性 总被引：15，自引：5，他引：10
通过研究太湖湖鲚的年龄结构、食物组成,结合太湖鱼类渔获量统计和环境检测资料,分析了1973-2002年间太 湖湖鲚渔获量变化的规律、原因及与生物环境间的相互关系．结果表明：1994年后湖鲚渔获量正以平均年增1430t 的速度 上升;种群中0~ 个体占99．04±2．21%(2003年)、99．08±0．80%(2004年);而0~ 湖鲚主要以浮游动物为食,其中枝角 类占食物总个数的89．77．80±13．69%．分析发现：湖鲚渔获量与 TIN、TN、COD 间的正相关关系均达到显著水平;与翘嘴 红鲌、银鱼产量间的负相关关系达到极显著水平;种群低龄化趋势加剧与捕捞强度不断升高相一致;浮游动物现存量有随 湖鲚渔获量升高而降低的趋势． 相似文献
5.
用花神湖、玄武湖、南湖的湖水培养隆腺溞,探讨不同营养水体的自然食物对隆腺溢生长、繁殖的影响,花神湖氮、磷营养盐浓度和浮游植物生物量均很低,用花神湖湖水培养的隆腺溞生长缓慢,个体在没有繁殖前就全部死亡,玄武湖氮、磷营养盐浓度和浮游植物生物量均低于南湖,但用玄武湖湖水培养的隆腺潘在生长速率、平均体长、生殖量上均高于用南湖湖水堵养的隆腺溞,实验结果表明:不同营养盐条件下,湖泊中浮游植物的组成有较大的差别,这种差别会对浮游动物生长、繁殖产生影响;在浮游植物种类和生物量适宜时,隆腺溞有较大的生殖量,浮游植物种类组成、浮游植物生物量的过低或过高都会抑制降腺溞的生长、生殖. 相似文献
6.
作为传统分类学方法的补充,本文以白鲫和鲫鱼的四个外形指标（全长、体长、体高和体重）进行Fisher多元线性判别分析,建立鉴别此二亚种的形态判别函数,以便对活体进行直接鉴定。检验表明,所得结果显著性极高,鉴别符合率达100%,且在渔业应用上简便易行。此外,本文还就在生物学中应用多元判别分析的一般方法作了简明扼要的阐述。 相似文献
7.
三峡水库以及上游江段形成的河—库生态系统与长江中下游洞庭湖和鄱阳湖的江湖生态系统都是四大家鱼的重要栖息地,有相似性也有差异.2017年7—8月在三峡水库、洞庭湖和鄱阳湖利用地笼、虾笼、高网和迷魂阵采集草鱼和鲢幼鱼样本,观测耳石日轮,分析三峡水库和通江湖泊草鱼和鲢幼鱼的繁殖时间和早期生长特征及差异,探讨相应的保护措施.结果显示,三峡水库、洞庭湖和鄱阳湖采集草鱼幼鱼的孵化日期分别为4月24日—5月25日、5月21日—6月26日和5月4日—5月28日;鲢幼鱼的孵化日期分别为4月10日—6月12日、5月25日—6月19日和5月9日—6月12日.三峡水库、洞庭湖和鄱阳湖草鱼样本的体长增长率分别为1.04、1.84和1.64 mm/d,微耳石的沉积率分别为3.41、5.41和4.77μm/d;鲢幼鱼的体长增长率分别为1.10、2.87和1.96 mm/d,微耳石沉积率分别为2.96、7.17和4.57μm/d.洞庭湖草鱼和鲢的体长增长率和耳石沉积率均显著大于三峡水库;鄱阳湖鲢的体长增长率和耳石沉积率均显著大于三峡水库,而草鱼的体长增长率和耳石沉积率则与三峡水库没有显著差异.结果表明,三峡水库蓄水后长江中游干流草鱼和鲢的繁殖时间明显滞后;洞庭湖和鄱阳湖的草鱼和鲢幼鱼生长更快.目前,长江全面禁渔正在逐步实施,预期将对恢复鱼类资源起到重要的作用.除了全面禁渔之外,还建议保护和修复鱼类栖息地;减少江湖阻隔,灌江纳苗;增殖放流亲鱼;开展生态调度,促进鱼类繁殖. 相似文献
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武汉后湖湖球蚬的周年生产量 总被引：2，自引：0，他引：2
采用体长频率法和瞬时生长率法对后湖湖球蚬Sphaerium lacustre的周年生产量进行了测算. 结果表明两种方法得到的生产量较为吻合.生产量的带壳湿重和去壳干重分别是体长频率法1.048 g/(m2a) 0.0599 g/(m2a); 瞬时生长率法1.178 g/(m2a), 0.0673 g/(m2a).对应的P/B系数为3.23.4. 相似文献
11.
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
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Hans van Haren 《Ocean Dynamics》2007,57(2):135-149
Relative ‘echo intensity’ data (dI) from a bottom-mounted four-beam 300 kHz acoustic Doppler current profiler (ADCP) are used to infer propagation of vigorous
processes above a continental slope. The 3- to 60-m horizontal beam spread and the 2-Hz sampling allow the distinction of
different arrival times t
i
, i = 1,..., 4, at different distances in the acoustic beams from sharp changes in dI-content associated with frontal non-linear and turbulent bores or ‘waves’. The changes in dI are partially due to variations in amounts of resuspended material carried by the near-bottom turbulence and partially due
to the fast variations in density stratification (‘stratified turbulence’), as inferred from 1-Hz sampled thermistor string
data above the ADCP. Such bores are observed to pass the mooring up to 80 m above the bottom, having typical propagation speeds
c = 0.15–0.5 m s−1, as determined from dI(t
i
). Particle speeds in the immediate environment of a bore amount to |u|env=c ± 0.05 m s−1, the equality being a necessary condition for kinematic instability, whilst the maximum particle speeds amount |u|max = 1.2–2c. The dI-determined directions of up-, down- and alongslope processes are all to within ±10° of the ADCP’s beam-spread averaged current
(particle velocity) data. 相似文献
14.
You-Kuan Zhang Jie Lin 《Stochastic Environmental Research and Risk Assessment (SERRA)》1998,12(2):117-140
Transport of non-ergodic solute plumes by steady-state groundwater flow with a uniform mean velocity, μ, were simulated with Monte Carlo approach in a two-dimensional heterogeneous and statistically isotropic aquifer whose transmissivity,
T, is log-normally distributed with an exponential covariance. The ensemble averages of the second spatial moments of the plume
about its center of mass, <S
i
i
(t)>, and the plume centroid covariance, R
i
i
(t) (i=1,2), were simulated for the variance of Y=log T, σ
Y
2=0.1, 0.5 and 1.0 and line sources normal or parallel to μ of three dimensionless lengths, 1, 5, and 10. For σ
Y
2=0.1, all simulated <S
i
i
(t)>−S
i
i
(0) and R
i
i
(t) agree well with the first-order theoretical values, where S
i
i
(0) are the initial values of S
i
i
(t). For σ
Y
2=0.5 and 1.0 and the line sources normal to μ, the simulated longitudinal moments, <S
11(t)>−S
11(0) and R
11(t), agree well with the first-order theoretical results but the simulated transverse moments <S
22(t)>−S
22(0) and R
22(t) are significantly larger than the first-order values. For the same two larger values of σ
Y
2 but the line sources parallel to μ, the simulated <S
11(t)>−S
11(0) are larger than but the simulated R
11 are smaller than the first-order values, and both simulated <S
22(t)>−S
22(0) and R
22(t) stay larger than the first-order values. For a fixed value of σ
Y
2, the summations of <S
i
i
(t)>−S
i
i
(0) and R
i
i
, i.e., X
i
i
(i=1,2), remain almost the same no matter what kind of source simulated. The simulated X
11 are in good agreement with the first-order theory but the simulated X
22 are significantly larger than the first-order values. The simulated X
22, however, are in excellent agreement with a previous modeling result and both of them are very close to the values derived
using Corrsin's conjecture. It is found that the transverse moments may be significantly underestimated if less accurate hydraulic
head solutions are used and that the decreasing of <S
22(t)>−S
22(0) with time or a negative effective dispersivity, defined as , may happen in the case of a line source parallel to μ where σ
Y
2 is small. 相似文献
15.
Transport of non-ergodic solute plumes by steady-state groundwater flow with a uniform mean velocity, μ, were simulated with Monte Carlo approach in a two-dimensional heterogeneous and statistically isotropic aquifer whose transmissivity,
T, is log-normally distributed with an exponential covariance. The ensemble averages of the second spatial moments of the plume
about its center of mass, <S
i
i
(t)>, and the plume centroid covariance, R
i
i
(t) (i=1,2), were simulated for the variance of Y=log T, σ
Y
2=0.1, 0.5 and 1.0 and line sources normal or parallel to μ of three dimensionless lengths, 1, 5, and 10. For σ
Y
2=0.1, all simulated <S
i
i
(t)>−S
i
i
(0) and R
i
i
(t) agree well with the first-order theoretical values, where S
i
i
(0) are the initial values of S
i
i
(t). For σ
Y
2=0.5 and 1.0 and the line sources normal to μ, the simulated longitudinal moments, <S
11(t)>−S
11(0) and R
11(t), agree well with the first-order theoretical results but the simulated transverse moments <S
22(t)>−S
22(0) and R
22(t) are significantly larger than the first-order values. For the same two larger values of σ
Y
2 but the line sources parallel to μ, the simulated <S
11(t)>−S
11(0) are larger than but the simulated R
11 are smaller than the first-order values, and both simulated <S
22(t)>−S
22(0) and R
22(t) stay larger than the first-order values. For a fixed value of σ
Y
2, the summations of <S
i
i
(t)>−S
i
i
(0) and R
i
i
, i.e., X
i
i
(i=1,2), remain almost the same no matter what kind of source simulated. The simulated X
11 are in good agreement with the first-order theory but the simulated X
22 are significantly larger than the first-order values. The simulated X
22, however, are in excellent agreement with a previous modeling result and both of them are very close to the values derived
using Corrsin's conjecture. It is found that the transverse moments may be significantly underestimated if less accurate hydraulic
head solutions are used and that the decreasing of <S
22(t)>−S
22(0) with time or a negative effective dispersivity, defined as , may happen in the case of a line source parallel to μ where σ
Y
2 is small. 相似文献
16.
Ａｌｉｇｎｍｅｎｔｓｉｌｋｗｏｒｍｓａｓｓｅｉｓｍｉｃａｎｉｍａｌａｎｏｍａｌｏｕｓｂｅｈａｖｉｏｒ（ＳＡＡＢ）ａｎｄｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｍｏｄｅｌｏｆａｆａｕｌｔ：ａｔｈｅｏｒｙａｎｄｌａｂｏｒａｔｏｒｙｅｘｐｅｒｉｍｅｎｔＭＯＴＯ... 相似文献
17.
The characteristic of seismic coda wave attenuation in Yunnan area in 7 frequency-bands range from 1 Hz to 20 Hz was estimated by using the local earthquake's waveform data recorded from 22 Yunnan digital seismic stations.Coda attenuation Q-c1 of each station was firstly calculated by single scattering method. Then, mean free path Le and seismic albedo Bo of each station were calculated, and scattering attenuation Q-1s and intrinsic attenuation Q-1i were separated from total attenuation Q-1t by multiple lapse time window analysis based on the multiple scattering model in uniform random isotropic scattering medium. The attenuating characteristics in Yunnan show that most value of Le are in 10～30 km, with maximal within 2～6 Hz;Bo are about 0.5 at 1～2 Hz, but less than 0.5at other frequency-bands, which means Q-1i is comparable with Q-1s at 1～2 Hz, and after 1～2 Hz, Q-1i is greater than Q-1s and dominates the attenuation process. Q-1c is close to Q-1i at other frequency bands except 1～2 Hz.Results show that Q-1 especially Qs-1 varies spatially, Q-1 in eastern Yunnan zone is a bit higher than in northwestern Yunnan zone;northwestern Yunnan zone higher than southwestern Yunnan zone. Comparing with other results in global, Qs-1 in Yunnan is lower than the global average value among these results, Q-1i is higher than the global average value, and Q-1t lies the middle among these results. 相似文献
18.
Age and generation of Fogang granite batholith and Wushi diorite-hornblende gabbro body 总被引：3，自引：0，他引：3
XU XiSheng? LU WeiMin & HE ZhenYu State Key Laboratory of Crust-Mantle Evolution Mineralization Department of Earth Sciences Nanjing University Nanjing China 《中国科学D辑(英文版)》2007,50(2):209-220
Fogang granitic batholith, the largest Late Mesozoic batholith in the Nanling region, has an exposure area of ca. 6000 km2. Wushi diorite-hornblende gabbro body is situated at the northeast part of the ba- tholith. Both the granitic batholith main body and the diorite-hornblende gabbro body belong to high-K calc alkaline series. Compared with the granitic main body, the Wushi body has lower Si (49%―55%), higher Fe, Mg, Ca, lower REE, less depletion of Eu, Ba, P, Ti, and obvious depletion of Zr, Hf. Zircon LA-ICP-MS dating and the mineral-whole rock isochron dating reveal that Fogang granitic main body and Wushi body were generated simultaneously at ca. 160 Ma. The Fogang granitic main body has high (87Sr/86Sr)i ratios (0.70871―0.71570) and low εNd(t) values (?5.11―?8.93), suggesting the origins of the granitic rocks from crustal materials. Their Nd two-stage model ages range from 1.37―1.68 Ga. The Sr and Nd isotopic compositions and the Nd model ages of the granitic rocks may suggest that the giant Fogang granitic main body was generated from a heterogeneous source, with participation of mantle component. Wushi diorite-hornblende gabbro is an unusual intermediate-basic magmatic rock series, with high (87Sr/86Sr)i ratios (0.71256―0.71318) and low εNd(t) values (?7.32―?7.92), which was possibly formed through mixing between the mantle-derived juvenile basaltic magma and the magma produced by the dehydration melting of lower crustal basaltic rocks. 相似文献
19.
实测和回归分析鄱阳湖鲌属(Culter)的翘嘴鲌(C.alburnus)、蒙古鲌(C. mongolicus)、达氏鲌(C.dabryi)和原鲌属(Culterichthys)的红鳍原鲌(C. erythropterus)体重与体维关系.结果表明,多元回归方程能全面地反映不同体维对鱼类体重的影响,体重与体侧面积体厚的回归方程较适宜.其体重(W)与体侧面积(A)及体厚(T)的幂函数关系式分别是,翘嘴鲌:W=4.05051×10-3A0.66260T1.41994;蒙古鲌:W=3.18603×10-3A0.66845 T1.44376;达氏鲌:W=1.99310×10-3A0.70982T1.47305;红鳍原鲌:W=3.58823×10-3A0.63253T1.49465. 相似文献