Many theories have been formulated

Many theories have been formulated to explain the role of grazers such as zooplankton in controlling the amount of planktonic algae (phytoplankton)in lakes. The first theories of such grazer control were merely based on observations of negative correlations between algal and zooplankton numbers. A low number of algal cells in the presence of a high number of grazers suggested, but did not prove, that the grazers had removed most of the algae. The converse observation, of the absence of grazers in areas of high phytoplankton concentration, led Hardy to propose his principle of animal exclusion, which hypothesized that phytoplankton produced a repellent that excluded grazers from regions of high phytoplankton concentration. This was the first suggestion of algal defenses against grazing.
Perhaps the fact that many of these first studies considered only algae of a size that could be collected in a net (net phytoplankton), a practice that overlooked the smaller phytoplankton (nannoplankton)that we now know grazers are most likely to feed on, led to a de-emphasis of the role of grazers in subsequent research. Increasingly, as in the individual studies of Lund, Round, and Reynolds, researchers began to stress the importance of environmental factors such as temperature, light, and water movements in controlling algal numbers. These environmental factors were amenable to field monitoring and to simulation in the laboratory. Grazing was believed to have some effect on algal numbers, especially after phytoplankton growth rates declined at the end of bloom periods, but grazing was considered a minor component of models that predicted algal population dynamics.
The potential magnitude of grazing pressure on freshwater phytoplankton has only recently been determined empirically. Studies by Hargrave and Geen estimated natural community grazing rates by measuring feeding rates of individual zooplankton species in the laboratory and then computing community grazing rates for field conditions using the known population density of grazers. The high estimates of grazing pressure postulated by these researchers were not fully accepted, however, until the grazing rates of zooplankton were determined directly in the field, by means of new experimental techniques. Using a specially prepared feeding chamber, Haney was able to record zooplankton grazing rates in natural field conditions. In the periods of peak zooplankton abundance, that is, in the late spring and in the summer, Haney recorded maximum daily community grazing rates, for nutrient-poor lakes and bog lakes, respectively, of 6.6 percent and 114 percent of daily phytoplankton production. Cladocerans had higher grazing rates than copepods, usually accounting for 80 percent of the community grazing rate. These rates varied seasonally, reaching the lowest point in the winter and early spring. Haney’s thorough research provides convincing field evidence that grazers can exert significant pressure on phytoplankton population

結果 (中文) 1:

为了解释的草食动物如浮游动物中湖泊浮游藻类 (浮游植物) 的总量控制的作用，已制定了很多理论。这种食草动物，控制第一种理论只被基于观测的负相关关系藻类和浮游动物数字。大量低的藻细胞存在大量食草动物的建议，但没能证明 — — 食草动物已吞噬了大部分水藻。匡威的观察，食草动物区高浮游植物浓度，缺乏带领哈代提出他的动物排斥，假设那浮游植物的原则产生排除地区高浮游植物浓度的食草动物驱蚊。这是对放牧的藻类防御的第一个建议。也许事实上这些第一次研究的很多人认为只有藻类的大小，可以收集成一张网 (净浮游植物)，被忽视的小的浮游植物 (超微化石)，我们现在知道食草动物是最有可能养活，实践导致我们的食草动物在随后的研究中的作用。越来越多，因为在隆德、 轮，和雷诺的个别研究，研究者开始强调环境因素，如温度、 光照、 和水控制藻类数量的变动。这些环境因素是适合向现场监测和实验室模拟。放牧被认为会有一些影响藻类的数量，尤其是后浮游植物的生长率下降在开花期，年底但放牧被认为是预测藻类种群动态模型的一小部分。潜在的淡水浮游植物的放牧压力程度只是最近才确定了实证研究。哈格雷夫和吉恩的研究估计自然群落食草比率通过测量出实验室内单独的浮游动物种类的滤食率，然后计算群落食草比率对于字段条件使用已知的种群密度的食草动物。放牧压力这些研究者所假设的高估计不被完全接受，然而，直到浮游动物的放牧率测定直接在字段中，通过新的实验技术。使用特制的饲养室，哈尼得以记录浮游动物，在自然的现场条件下放牧率。时期的浮游动物数量的高峰期，那就是，在春末和夏季，哈尼记录了最大的每日群落食草比率，对于营养充足的湖和沼泽湖而言，分别的 6.6%和 114%每日浮游植物繁殖。枝有放牧率高于桡足类，通常占社区放牧率 80%。在冬季和早春到达最低点，这些房价呈现明显季节性的变化。哈尼的深入研究提供了令人信服的实地证据食草动物可以施加重大压力浮游植物种群数量

結果 (中文) 3:

有许多理论来解释制定的食草动物如控制浮游藻类数量的浮游动物的作用（浮游植物）在湖泊。这种食草动物控制第一个理论是基于藻类和浮游动物数量间的负相关性的观察。少量的藻细胞在大量食草动物的存在的建议，但没有证明，