Cladoceran Size and the Abundance of Ciliates and Rotifers in Freshwater Zooplankton Communities

将进行实地和实验室研究，以检验纤毛虫和轮虫在只有小型枝角类物种的淡水浮游动物群落中比在大型枝角类物种中更丰富的假设。现场围栏实验将通过在纤毛虫和轮虫的自然群落中不添加枝角类、小型枝角类(Bosmina Long Girostris)或大型枝角类(Daphnia Pulex)来检验这一假设。这些实验将辅之以：1)实验室竞争实验，以测试蜗壳轮虫与不同大小的枝角类物种共存的能力；以及2)各种不同大小的纤毛虫物种对不同大小的枝角类物种的机械干扰(损害、捕食)的敏感性的实验室实验和观察。这项研究的结果将有助于理解纤毛虫和轮虫在自然群落中重要性的变化，以及浮游食肉动物对自然群落中大型枝角类动物的选择性捕食的次要影响。这项研究将是第一次广泛调查枝角类和纤毛虫之间的相互作用，并评估枝角类对自然群落中纤毛虫的影响。

Field and laboratory studies will be conducted to test the hypothesis that ciliates and rotifers will be more abundant in freshwater zooplandton communities with only small cladoceran species than in those with large cladoceran species. In situ enclosure experiments will test this hypothesis by adding no cladocerans, small cladocerans (Bosmina longirostris), or large cladocerans (Daphnia pulex) to natural communities of ciliates and rotifers. These experiments will be supplemented by: 1) laboratory competition experiments to test the ability of the rotifer Keratella cochlearis to coexist with different-sized cladoceran species; and 2) laboratory experiments and observations on the susceptibilities of a variety of different- sized ciliate species to mechanical interference (damage, predation) from different-sized cladoceran species. The results of this research should be useful in understanding variation in the importance of ciliates and rotifers in natural communities and secondary effects of zooplanktivorous fish, which prey selectively on large cladocerans in natural communities. This study will be the first to extensively investigate interactions between cladocerans and ciliates, and to assess the impact of cladocerans on ciliates in natural communities.