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

将进行实地和实验室研究，以验证这样一种假设，即纤毛虫和轮虫在只有小枝海纲物种的淡水植物群落中比在有大枝海纲物种的淡水植物群落中更丰富。原位封闭实验将通过在纤毛虫和轮虫的自然群落中添加无枝海目、小枝海目（波斯米纳长尾海目）或大枝海目（水蚤）来验证这一假设。这些实验将辅以：1)实验室竞争实验，测试耳蜗角轮虫与不同大小的支海洋物种共存的能力；2)不同体型纤毛虫对不同体型纤毛虫的机械干扰（损伤、捕食）敏感性的室内实验和观察。本研究结果将有助于理解自然群落中纤毛虫和轮虫重要性的变化，以及浮游动物食性鱼类在自然群落中选择性捕食大型枝海洋动物的次生效应。本研究将首次广泛研究枝大洋与纤毛虫之间的相互作用，并评估自然群落中枝大洋对纤毛虫的影响。

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.