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模糊秀体潘是热带水体中枝角类的主要优势种，它在竞争及对热带水体的适应方面的优势尚不清楚。本文以模糊秀体潘为研究对象，观察不同食物浓度下其生长和繁殖的特点，探讨模糊秀体潘成热带水体优势种的原因。以蛋白核小球藻为食物，浓度梯度设为0.05mg／L、0.1mg／L、0.3mg／L、0.6mg／L和1.0mg／L小球藻浓度为0.05mg／L的培养液中，模糊秀体潘存活率很低且未观察到繁殖现象其它4个浓度小球藻喂养的模糊秀体潘体长生长率和最大体长均随食物浓度的升高而增加，最大体长分别达到1.087mm、1.125mm、1.225mm、1.313mm；食物浓度对模糊秀体溢的胚胎发育时间，平均寿命，个体累计产幼数无显著影响：随着食物浓度的升高，模糊秀体滏初次怀卵体长显著增加，繁殖前期的历时相应缩短，平均每胎产幼数增加：内禀增长率随食物浓度升高而增大，达到0.6mg／L后比较稳定。浓度为0.6mg／L时，模糊秀体潘的净生殖率也达到最大值。1.0mg／L组的世代时间最短，内禀增长率接近最大值。0.6mg／L和1.0mg／L为模糊秀体潘生长比较适宜的食物浓度。热带自然水体中，模糊秀体潘相对其它浮游动物个体小和怀卵率低的现象并非食物不足所致；食物充足条件下的最大成体的个体大小与野外样品接近，也说明自然水体中捕食并没有显著影响成体的个体大小。模糊秀体潘体型较小、身体透明、行动敏捷，容易逃避鱼类的捕食，可能是模糊秀体潘能在食物丰富的热带水体中，特别是透明度较低的富营养化湖泊中能够成为枝角类中优势种的主要原因。 相似文献
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以引力模型、城市流模型、交通可达性模型、信息通达性模型为基础构建城市群空间联系强度综合评价模型,结合GIS空间分析方法,研究2004—2013年滇中城市群城市空间联系的时空演变。结果表明:1滇中城市群城市空间联系强度逐渐增加,区域差异明显,联系强度总体偏低;2城市群空间联系方向以昆明为中心呈圈层式向外辐射及沿南部、东北交通干线呈轴线式空间拓展,西北部空间联系强度最弱;3城市经济发展水平与交通状况对区域空间联系强度影响较大,通过产业结构转型及交通道路网完善,可以实现城市群的协调发展。 相似文献
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We investigated the allelopathic properties of Alexandrium tamarense (Laboar) Balech on the growth of Prorocentrum donghaiense Lu, Chattonella marina (Subrahmanyan) Hara et Chihara and Heterosigma akashiwo (Hada) Hada in a laboratory experiment. We examined the growth of A. tamarense, C. marina, P. donghaiense and H. Akashiwo in co-cultures and the effect of filtrates from A. tamarense cultures in various growth phases, on the three harmful algal bloom (HAB)-forming algae. In co-cultures with A. tamarense, both C. marina and H. akashiwo were dramatically suppressed at high cell densities; in contrast, the growth of P. donghaiense varied in different inoculative ratios of A. tamarense and P. donghaiense. When the ratio was 1:1 (P. donghaiense: A. tamarense), growth of P. donghaiense was inhibited considerably, while the growth of P. donghaiense was almost the same as that of the control when the ratio was 9:1. The growth difference of P. donghaiense, C. marina and H. akashiwo when co-cultured with A. tamarense indicated that the allelopathic effect may be one of the important factors in algal competition and phytoplankton succession
involving A. tamarense. In addition, the filtrate from A. tamarense culture had negative impacts on these three HAB algae, and such inhibition varied with different growth phases of A. tamarense in parallel with reported values of PSP toxin content in Alexandrium cells. This implied that PSP toxin was possibly involved in allelopathy of A. tamarense. However, the rapid decomposition and inactivation of PSP toxin above pH 7 weakened this possibility. Further studies on
the allelochemicals responsible for the allelopathy of A. tamarense need to be carried out in future. 相似文献
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