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2004年10月至2005年8月，对不同季节千岛湖蚤状潘的垂直分布情况以及昼夜迁移进行了研究。结果表明，蚤状潘在千岛湖分布广泛，春季和夏季蚤状潘主要分布在15-25m水层，而在秋冬季分布相对均匀，从表层到60m水深都有分布；比较了蚤状漫在不同季节的迁移现象，春季和秋季蚤状潘为夜间迁移模式，而在夏季和冬季虽然都存在迁移现象，但不同于常见的三种迁移模式。 相似文献
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Individual based simulations of population dynamics require the availability of growth models with adequate complexity. For this purpose a simple-to-use model (non-linear multiple regression approach) is presented describing somatic growth and reproduction of Daphnia as a function of time, temperature and food quantity. The model showed a good agreement with published observations of somatic growth (r2 = 0.954, n = 88) and egg production (r2 = 0.898, n = 35). Temperature is the main determinant of initial somatic growth and food concentration is the main determinant of maximal body length and clutch size. An individual based simulation was used to demonstrate the simultaneous effects of food and temperature on the population level. Evidently, both temperature and food supply affected the population growth rate but at food concentrations above approximately 0.4 mg Cl−1 Scenedesmus acutus temperature appeared as the main determinant of population growth.
Four simulation examples are given to show the wide applicability of the model: (1) analysis of the correlation between population birth rate and somatic growth rate, (2) contribution of egg development time and delayed somatic growth to temperature-effects on population growth, (3) comparison of population birth rate in simulations with constant vs. decreasing size at maturity with declining food concentrations and (4) costs of diel vertical migration. Due to its plausible behaviour over a broad range of temperature (2–20 °C) and food conditions (0.1–4 mg Cl−1) the model can be used as a module for more detailed simulations of Daphnia population dynamics under realistic environmental conditions. 相似文献
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有毒铜绿微囊藻对鱼和溞的毒性 总被引：12，自引：2，他引：12
用有毒铜绿微囊藻细胞及其从毒细胞中提取的毒素喂养和腹腔注射鱼类，结果表明：（1）微囊藻毒素MCYST－LR对所有实验过的鱼有毒害作用（LD_(50)为110－500μg／kg）．注射毒素24h后，鱼肝电镜超微结构观察均表现出肝损伤．（2）在受控条件下，当用有毒铜绿微囊藻作为食物喂养日鲢和罗非鱼时，鱼类能在以毒藻为唯一食物的环境中生活20d以上．白鲢和罗非鱼粪便的毒性比喂食藻类的毒性分别降低约2—4．5倍，其肝的超微结构现察仍有轻度损伤．（3）在培养液中加入15μg／mLMCYST－LR和用实验室纯培养的铜绿微囊藻作为食物培养枝角类时，均可使它们在48h死亡．以无毒微囊藻培养时则生长不良亦不怀卵，表明它不是枝角类合适的食物． 相似文献
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To establish a base line against which future pollution may be measured, eight common commercial species of New Zealand sea fish were analysed for cadmium, chromium, copper, iron, lead, manganese, nickel, and zinc. One sample of edible muscle tissue was analysed for each of 70 samples of each species. The internal organs of up to five specimens of each species were also analysed. The fish studied were: kahawai, Arripis trutta, trevally, Caranx lutescens, tarakihi, Cheilodactylis macropterus, snapper, Chrysophrys auratus, moki, Latridopsis ciliaris, hapuku, Polyprion oxygeneios, kingfish, Seriola grandis and gurnard, Trigla kumu. Although, none of the edible parts of the fish appeared to have trace element levels likely to be a public health problem (cadmium 0.002–0.02 ppm, chromium 0.01–0.04 ppm, copper 0.04–0.95 ppm, iron 0.9–13.5 ppm, lead ‘ 0.14–0.95 ppm, manganese 0.04–2.00 ppm, nickel 0.01–0.08 ppm, zinc 2.0–36.0 ppm), some of the organs (particularly the liver) had relatively high concentrations of elements such as cadmium (up to 54 ppm). Only if some industry were to seek to exploit internal organs of fish for human consumption would such levels become important. There was some evidence for a relationship between trace element concentrations and fish size for copper in kingfish and snapper, iron in hapuku, manganese in gurnard, and for zinc in kingfish and tarakihi. Some element pairs such as copper and zinc, iron and manganese, appeared to have concentrations which were mutually related. It was assumed that the elemental concentrations reported represent natural levels and are not the result of significant man‐made pollution because there are no major industries or large urban centres adjacent to the fishing grounds. 相似文献
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David G. Frey 《Journal of Paleolimnology》1991,6(3):193-197
Silty pond sediments from Wulff Land in northernmost Greenland, radiocarbon dated 10480 BP, yielded many headshields, shells, and ephippia of Daphnia pulex, and headshields, shells, ephippia, and one postabdomen of Alona guttata. This is the first documentation of recognizable headshields and shells of Daphnia in the fossil record. 相似文献
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利用人工配制的生活污水先进行单胞藻（斜生栅藻 Ｓｃｅｎｅｄｅｓｍｕｓ ｏｂｌｉｑｕｕｓＴｕｒｐ）的 培养,再接种田螺（Ｃｉｐａｎｇｏｐａｌｕｄｉｎａ ｓｐ）和短钝溞（Ｄａｐｈｎｉａ ｏｂｔｕｓａ Ｋｕｒｚ）,对栅藻密度的经时变化, 短钝溞种群增长及水体中氮、磷、碳在培养过程中的变化作了测定与分析结果如下：（１）田螺组和 对照组中栅藻密度（Ｎ）经时变化的函数为：田螺组Ｎ＝ｅ（１．１１３６）ｔ（１．７２０４）;对照组Ｎ＝ｅ（１．４１７５）ｔ（１．８０９９）;（２）田 螺组短钝溞在静态条件下的种群增长模型为： Ｎ＝ ０． ７５ｅ（０．４７６）ｔ,（３）以短钝溞问收方式收获量的累加 值作为种群增长量（产出量）,其数学模型为：Ｎ＝ｅ（０．２８３７）ｔ（２．５５３７）;（４）经栅藻、田螺、短钝溞培养后,生 活污水的氮、磷、碳含量分别下降了 ８０、 ６０％, ７２． ４０％, ４５． ７０％． 本研究既为枝角类集约化培养提供了某些生态学理论参数,也为污水调控及资源化提出一个 值得参考的技术途径 相似文献
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南京玄武湖隆腺溞(Daphnia carinata)牧食对浮游植物的影响 总被引：1，自引：1，他引：0
隆腺溞(Daphnia carinata)是许多湖泊的常见大型浮游动物,习居于富营养的水域中,以浮游植物为食,且滤食效率较高.通过浮游动物添加实验,研究了隆腺潘对南京玄武湖叶绿素和浮游植物群落结构的影响.结果表明,在隆腺涵组,浮游植物密度较对照组降低了83%,叶绿素较对照组下降了81%,氮、磷营养盐与叶绿素的相关性不显著.浮游植物的群落结构较对照组也发生了很大变化,蓝藻、绿藻和硅藻的比例有显著上升,隐藻呈显著下降趋势,金藻、甲藻和裸藻在实验结束时已没有检出.说明隆腺潘的摄食能有效控制浮游植物的生物量,可对浮游植物的群落结构产生显著影响. 相似文献
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表型可塑性指的是生物体在生物或非生物环境发生变化时会呈现出不同的表型能力,是生物在不稳定的生活环境中维持生存的一种主要策略.在淡水生态系统,大量研究表明浮游动物能通过捕食者释放的化学信息物质感知捕食风险的存在,从而导致反捕食的表型可塑性反应的发生.溞类是一类很好的研究浮游动物对捕食者释放的信息素产生表型可塑性反应的模式生物.本文综述了捕食者释放的化学信息素对溞类的生活史、形态特征、行为活动以及生理指标等表型的影响,探讨了其形成机制和生态意义.溞类对捕食风险信息素的表型可塑性是特定种群与捕食者长期相互作用下适应性进化产生的.加强这些研究对了解物种的形成和生物的进化有非常重要的意义. 相似文献