A test of recruitment limitation in some stream insects

这项研究的总体目的是考察不同生活史阶段对一些溪流昆虫局部种群动态的贡献。了解限制种群数量的因素是生态学家普遍感兴趣的一个具有挑战性的问题，也对保护和环境管理的良好实践至关重要。传统上，淡水生态学家将重点放在昆虫的水生幼虫阶段，而对水生幼虫和陆生成虫之间的过渡阶段的关注较少。我们将专注于将陆生卵子招募到水生介质中，并将这些卵子转化为新生儿，帮助填补关于这些生命阶段的生态的实质性知识空白。这两个阶段中的任何一个或两个阶段似乎都有可能成为种群的“瓶颈”。仅仅是找到一个合适的产卵地点就可以限制种群数量。许多溪流昆虫在从水面涌出的溪流岩石的底部产卵，我们将测试涌出岩石的供应是否会限制卵的招募。此外，产卵的雌性可能会受到出露岩石(产卵地点)的空间安排的影响，我们还将测试这如何影响招募。一旦卵子孵化，新生儿的流动性将决定紧急岩石限制的任何局部影响是否或持续多久，通过测量新生儿的运动，我们将确定与种群动态研究相关的空间尺度。或者，紧急岩石限制的影响可能被卵子或新生儿的高死亡率所淹没，这表明了招募限制的不同潜在机制。新出现的岩石、蛋和新生儿之间缺乏任何模式，这表明种群规模是由不同的生命阶段决定的，后续的研究工作可以针对这些阶段。因此，我们的研究将确定卵子和新生儿生活史阶段是否出现瓶颈，这些瓶颈可能有多强，以及限制发生的空间尺度。这些结果对种群动力学的生态模型具有重要意义。有关昆虫如何利用浮生岩石的信息，将对河流管理人员和修复项目有用。

The general aim of this research is to examine the contribution of different life history stages to the local population dynamics of some stream insects. Understanding the factors that limit population size is a challenging problem of widespread interest among ecologists, and also of vital importance to sound practice in conservation and environmental management. Traditionally, freshwater ecologists have focused on the aquatic, juvenile stages of insects, with considerably less attention devoted to the transition stages between the aquatic juveniles and terrestrial adults. We will concentrate on the recruitment of eggs from the terrestrial into the aquatic medium and the conversion of those eggs into neonates and help fill a substantial knowledge gap about the ecology of these life stages. It seems likely that either or both of these stages may act as populations 'bottlenecks'. Simply finding a suitable location to lay eggs may limit population size. Many stream insects lay their eggs on the underside of stream rocks that are emergent from the water's surface and we will test whether the supply of emergent rocks might limit egg recruitment. Further, egg-laying females may be influenced by the spatial arrangement of emergent rocks (egg-laying sites) and we will test also how this influences recruitment. Once the eggs hatch, the mobility of neonates will dictate whether or how long any localised effects of emergent rock limitation persist and, by measuring neonate movement, we will identify the spatial scale relevant to studies about population dynamics. Alternatively, effects of emergent rock limitation may be overwhelmed by high mortality of eggs or neonates, suggesting a different underlying mechanism for recruitment limitation. A lack of any pattern between emergent rocks, eggs and neonates, would suggest that populations size is set by different life stages and subsequent research efforts can be directed at those stages. Thus, our research will identify whether bottlenecks occur for egg and neonate life history stages, how strong those bottlenecks might be, and the spatial scales at which the restrictions occur. These results are of fundamental importance to ecological models of population dynamics. Information on how insects use emergent rocks, will be of use to river managers and rehabilitation projects.