排序方式： 共有48条查询结果，搜索用时 151 毫秒
41.
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
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富营养湖泊中蓝藻水华对枝角类种群和群落结构有显著的影响,但自然条件下群体微囊藻对大型枝角类溞属不同种类的影响仍存在争议.本研究通过两次为期各10 d的模拟实验,利用过滤后的太湖原水模拟群体微囊藻(20～100μm和100 ～200 μm)添加对大型枝角类同形溞(Daphnia similis)种群特征的影响,结果显示两次实验的同形溞均大量存活,不同浓度和颗粒大小的群体微囊藻对其生长和繁殖的影响不同,添加群体微囊藻的同形溞的生长和繁殖显著大于未添加微囊藻的.说明在自然条件下藻毒素对同形溞种群并没有明显的抑制作用,同形溞能够与微囊藻水华共存,其种群特征与微囊藻群体大小组成和生物量有关. 相似文献
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Anita A. C. Pearson 《新西兰海洋与淡水研究杂志》2019,53(3):327-337
Interactions between two recent invaders to New Zealand, the cladocerans Daphnia galeata and D. pulex, and native filter-feeding freshwater mussels, are unknown. We examined predation rates of the common native mussel Echyridella menziesii (kākahi, kāeo) on non-native Daphnia (comparatively large zooplankton in New Zealand), relative to two common native species, the smaller cladoceran Bosmina meridionalis and rotifer Brachionus calyciflorus. Controlled laboratory experiments were conducted in which each zooplankton species was exposed to bivalve predation for a two-hour period. Comparing treatments to non-mussel controls, removal rates of non-indigenous D. pulex and native B. calyciflorus were statistically significant. Nevertheless, kākahi removal rates may not be ecologically significant for daphnids (1.7% D. galeata and 7.4% D. pulex). Kākahi removed 8.8% of B. meridionalis and 30.2% of B. calyciflorus, suggesting that small, feeble zooplankton species (particularly rotifers) are most susceptible to predation, and potentially function as an energy source for native freshwater mussels. 相似文献
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Vicky A. Reid Gary R. Carvalho D. Glen George Huw I. Griffiths 《Journal of Paleolimnology》2002,27(4):481-486
The Polymerase Chain Reaction (PCR) was employed to facilitategenetic analyses of Daphnia ephippial egg banks fromsediment sequences from lakes Windermere and Esthwaite in the English LakeDistrict, UK. We present a robust DNA extraction technique for resting eggs andan account of genetic characterisation of dated resting eggs from sedimentcores using both mitochondrial and nuclear DNA markers. We also providepreliminary results from genetic analysis of egg banks preserved in shortsediment cores. PCR was employed to facilitategenetic analyses of Daphnia ephippial egg banks collected from both lakes. Thelong-term environmental data available from lake records can provide a backdropagainst which molecular genetic-environmental interactions over time can beexamined, providing a technique for direct assessments of population responseto environmental change in paleolimnological studies of biodiversityhistory. 相似文献
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太湖夏秋季大型枝角类(Daphnia)种群消失的初步分析 总被引：2，自引：2，他引：0
水体温度过高和磷浓度是影响枝角类Daphnia存活和繁殖的重要因子,因此本研究假设太湖夏秋季水体高温和磷浓度是引起Daphnia种群夏秋季消退的原因.通过夏秋季两次为期各15d的模拟实验,模拟高温和添加磷盐对太湖春季优势种同形溞Daphnia similis种群的影响,结果表明在高温和不添加磷盐的条件下,同形溞均有较高的种群增长率,证实夏秋季太湖水体高温和磷浓度不是限制Daphnia种群的因素,同时推测,鱼类的捕食作用和微囊藻水华对Daphnia种群的消退可能起作用. 相似文献
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Emine Batürk 《洁净——土壤、空气、水》2019,47(12)
The water quality of Mamas?n Dam, the drinking water source for Aksaray in Turkey, is investigated for assessment of ecological and health risks according to data between December 2015 and November 2016. Water quality index, ecological risk, and health risk assessments are determined to depend on the intensity of occurrence of parameters and seasonal and spatial distributions at different depth ranges. As a result, some ions such as Al, As, B, Ba, Co, F, Mn, Ni, Pb, Se, and Zn were found to be exceeding the limit values of the national regulatory standards. Besides, Pb is listed in Priority Substances and Certain Other Pollutants according to Annex II. Because the WQI values of the water quality are low (below 60), the source is suitable for industrial and agricultural usage; however, it cannot be used for drinking water supply without treatment. The trace element levels, especially Ag, Ba, Cu, Cr, and Zn, are potential pollutants for organisms. The non‐carcinogenic health risks of As threaten both adults and children at “medium” and “high” levels through oral ingestion. The B, F, and Pb elements have Hazard Index values above 0.1 and may cause a “low” level risk chronic disease for children by oral ingestion. 相似文献
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利用Long-PCR及普通PCR技术,结合引物步移法测序,经拼接、组装后获得中国淮河大型溞(Daphnia magna)线粒体基因组全序列,并对其基因组成、结构特点等进行初步分析.大型溞线粒体基因组全长为14948 bp,A、T、G、C各碱基含量分别为32.37%、34.73%、15.58%、17.31%,表现出明显的AT偏倚.13个蛋白质编码基因、22个t RNA基因、2个rRNA基因和1个D-loop区(控制区)的排列方式与典型的节肢动物线粒体基因组的排列方式略有不同.除COI基因以CTG、ATP8基因以GTG、ND3基因以ATC以及ND6基因以ATT为起始密码子以外,其余9个蛋白质编码基因均以ATG作为起始密码子;9个蛋白质编码基因具有典型的完全终止子TAG或TAA,COI、COII、ND4和ND5等基因采用不完全终止密码子T.基因组包含9个基因间隔区,共81 bp,长度1~62 bp;13个基因重叠区,共77 bp,重叠碱基数在1~27 bp之间,最大重叠在16 S rRNA和tRNA~(Val)基因之间.在预测的22个tRNA基因的二级结构中,发现只有tRNA~(Ser1)基因未能形成完整的二级结构,其他21个基因均可形成典型的三叶草结构.16 S rRNA和12 S rRNA基因长度分别为1373 bp和752 bp,D-loop区全长289 bp.本研究结果为探讨大型溞在溞属中的系统学地位及其与其他种间的系统发生关系等问题提供了数据资源. 相似文献