Fish assemblages as influenced by environmental factors in streams in protected areas of the Czech Republic

Abstract –  Three streams of comparable size located in different landscape-protected areas were selected for studying the effect of environmental factors on fish assemblages using indirect (detrended correspondence analysis, DCA) and direct (canonical correspondence analysis, CCA) gradient analysis. DCA of species showed well a gradient of assemblage changes in the longitudinal profile. DCA of sites stressed the variability between the fish assemblages of the three streams. This pattern was then confirmed by the highly significant between-stream CCA. In the within-site CCA, environmental factors explained 50.7% variability for presence–absence data and 58.3% for the relative abundance data. The analysis revealed that number of ponds and land use are the most influential factors of the strongest environmental gradient. However, in the partial CCAs, factor substratum type explained the largest proportion of the variability affecting fish in their habitat choice. Generally, presence–absence and relative abundance data of fish gave similar results in both DCA and CCA analyses; the same environmental factors proved to be important in both data type analyses. The environmental factors explain more variability than the regional (between-stream) one. The total proportion of variability explained by the presence–absence data analysis was 71.9% and in the relative abundance analysis even 80.8%. The environmental factors measured during the field survey explain 2.1- and 3.4-times more assemblages' variability than factors measured from a hydrological map.     

Discrimination and abundance estimation of wild and released abalone Haliotis diversicolor using stable carbon and oxygen isotope analysis in north-eastern Taiwan

The discrimination between wild and released Taiwan abalone Haliotis diversicolor was performed by stable carbon isotope analysis. Abalone samples were collected from Mao Aw Gulf in north-eastern Taiwan. Live abalone and dead shells were collected by divers with an 80 × 80 cm frame. The densities and amounts of wild and released abalone, as well as the survival rates of released abalone, in 1997 and 1998 were estimated. The age of the specimens was also determined from the specific temperature of each month and the inverse relationship between oxygen isotope values and temperatures. Results show that examining stable isotopic profiles proves to be a practical and feasible method for stock discrimination as well as density and abundance estimation. These data would be helpful in assessing the success of abalone culture and release programs, which aim to enhance this valuable marine resource.     

饲料资源量概念及其判断

首先提出并讨论了饲料资源量的主体部分就是饲料能量总量及饲料蛋白质总量的问题。然后,用相关及回归方法筛选出了牛代谢能及粗蛋白质指标。在此基础上,建立了对饲料资源的品质和数量进行判断的蛋能结构指数及蛋能丰度指数体系。     

Abundance estimates of perch fry (Perca fluviatilis), complicated by grouped behaviour

Schnabel's mark and recapture abundance estimates of perch fry in Kli?ava Reservoir (Czech Republic), differentially marked in autumn and in spring, partly failed due to the existence of groups of individuals which behaved differently. There were three groupings. 1) a group of fry caught by shore seining from autumn of the first year (O+) to summer of the second year of life (1+), the only group in the littoral during late autumn and early spring and the fry with the slowest growth rate; 2) a group of perch fry that consisted of males maturing at 1 year and that dominated the trap catches in reservoir; 3) a group of fry that avoided the littoral in late autumn and during March-May 1983, which appeared in the littoral in May and June 1983, thus diluting the previously marked littoral fry. These 3 groupings of fry were relatively stable and separable throughout 1–2 years, apart for the mixing of groups 1 and 3 that took place in the littoral during the summer. The density of perch fry of 1982 year class in spring 1983 was estimated to be about 0.094 individuals per m².     

姬松茸儿种胞外酶的最适反应pH的最适反应温度

姬松茸的胞外CMC酶，FP酶，βGase,HC酶,淀粉酶和果胶酶的最适反应pH和最适反应温度分别是4．6和55℃，5．2和50℃，4．6和50℃，5．8和40℃，4．0和50℃，菌丝最适生长pH下的相对酶活力系数远远小于酶最适反应pH下的相对酶活力系数；菌丝最适生长温度下的相对酶活力系数远远小于酶最适反应温度下的相对酶活力系数。     

桂花叶片水分含量及光合生理特性的研究

以柳叶桂、山桂和四季桂3个桂花品种为试材,研究了其水分、光合色素的含量以及净光合速率(Pn)、蒸腾速率和叶绿素荧光(Fv/Fm)的日变化。结果表明:山桂和柳叶桂的各种水分和光合色素的含量差异不显著,但与四季桂差异显著,其Pn日变化和蒸腾速率日变化都呈现先上升后下降的单峰曲线;Pn峰值出现在10:00左右,而蒸腾速率的峰值出现在12:00左右,最大光化学效率日变化呈单峰曲线,但呈现先下降后上升趋势。     

森林-草原交错带土壤节肢动物物种相对多度模型拟合研究

应用群落物种多度分布模型:对数级数分布模型、对数正态分布模型、几何级数分布模型和分割线段分布模型研究了森林草原交错带土壤节肢动物群落的种-多度分布关系。结果表明:对数级数分布模型和对数正态分布模型能够较好的拟合交错带大型土壤节肢动物群落的种-多度分布,中小型土壤节肢动物仅能用对数级数分布模型来拟合;几何级数分布模型和分割线段分布模型则不适于描述该区土壤节肢动物群落物种多样性。对数级数分布的参数α和对数正态分布的参数λ是反映群落结构特征内在性质的量,可以作为物种多样性指数运用,能较好地反映群落的物种丰富度。研究结果可为交错区群落物种多样性保护提供理论基础。     

小麦杂种F_3代茎秆机械强度的选择效应分析

以山农3068/济麦4072、山农3068/济麦20两个组合的F3、F4群体为试材,研究了高、中、低三类茎秆机械强度类群的选择效应。结果表明:F3代高机械强度类群的直接选择在F4代获得了较高的相对遗传进度;不同类群的茎秆机械强度的选择对其他抗倒性状的影响不同,其中高机械强度类群的选择能有效降低抗倒指数,从而提高抗倒性;不同机械强度类群的选择都提高了千粒重,但减少了穗粒数,对穗数的影响较小,总体上利于单株产量的提高。     

15种中草药对体外新孢子虫抑制效果的比较研究

[目的]筛选抗新孢子虫效果较好的中药。[方法]用新孢子虫虫体感染非洲绿猴肾细胞(Vero),观察细胞生长状态,并通过台酚蓝染色试验,计算各孔虫体死亡率和相对抑制率。[结果]黄芩、百部、天麻、黄连、槟榔、鸦胆子对体外培养的新孢子虫具有较好的杀灭和抑制作用。[结论]该研究为新孢子虫病的临床治疗提供依据。