Facilitators and outcomes of biological invasions by aquatic macrophytes

入侵物种是指被引入一个新的地理区域并随后扩大了它们的范围，同时主导了新的栖息地的非本地物种。在这个过程中，入侵物种可以取代本地物种，将病原体引入经济重要物种，改变生态系统过程，并扰乱人类娱乐场所。在过去的几十年里，入侵物种的数量一直在稳步增长，现在它们构成了对世界各地生态系统和生物多样性的最大威胁之一。此外，入侵物种会招致巨大的经济成本，因为它们可能会导致商业上重要的物种大量死亡，总体上需要广泛而昂贵的管理和预防计划。相当多的研究已经解决了生物入侵的许多方面，但我们仍然有一些非常重要的知识空白需要填补。这方面的一个例子是，我们对为什么一些引进的(非本地)物种变得入侵，而另一些物种要么灭绝，要么维持在非常低的水平，对周围的栖息地几乎没有影响，理解得很差。第二个知识鸿沟围绕入侵物种的群落影响：尽管我们知道入侵物种的总体影响是负面的，但我们并不完全了解它们在不同空间尺度上对生物多样性的影响或它们对不同类型栖息地的影响，例如它们是否最有可能入侵已经退化的、对许多本地物种来说不够用的栖息地。生物入侵的这两个方面--入侵的可能性和影响--在水生系统中的研究尤其不足。我建议使用野外、实验和实验室工作相结合的方法来回答以下问题：1)非本地植物对安大略省水生系统的入侵取决于环境条件和本地植物的竞争能力，换句话说，植物更有可能入侵本地物种没有时间适应的最近改变的区域？2)入侵植物通过减少本地生物多样性和使系统更容易受到其他物种的入侵，在多大程度上改变了水生生态系统？通过填补其中一些关键的知识空白，我的研究将帮助管理者通过优先考虑预防策略的地点来防止生物入侵，要么是因为这些地点特别容易受到入侵，要么是因为这些地点特别可能在入侵后经历广泛的有害影响。预防是一种远比清除已建立的入侵更成功的战略，因此我的研究将为加拿大提供可观的经济和社会效益。

Invasive species are non-native species that were introduced into a new geographical region and subsequently expanded their range while dominating new habitat. During this process, invasive species can displace native species, introduce pathogens to economically important species, alter ecosystem processes, and disrupt sites of human recreation. The numbers of invasive species have been steadily growing over the last few decades, and now they now comprise one of the biggest threats to ecosystems and biodiversity around the world. Furthermore, invasive species incur tremendous economic cost because they can decimate commercially important species, and collectively require extensive and costly management and prevention programs. ******Considerable research has addressed many aspects of biological invasions, but we still have a number of very important knowledge gaps that need to be filled. One example of this is our poor understanding of why some introduced (non-native) species become invasive, while others either go extinct or are maintained at very low levels with little to no impact on their surrounding habitat. A second knowledge gap surrounds the community effects of invasive species: although we know that the overall impact of invasive species is negative, we don't fully understand their effects on biodiversity across different spatial scales or their impacts on different types of habitat, e.g. whether they are most likely to invade habitat that has already deteriorated and is inadequate for many native species. These two aspects of biological invasions the likelihood and the effects of invasions - are particularly understudied in aquatic systems. I propose using a combination of field, experimental and lab work to answer the following questions: 1) Do invasions of Ontario aquatic systems by non-native plants depend on a combination of environmental conditions plus the competitive ability of native plants, in other words are plants more likely to invade recently altered areas to which native species have not had time to adapt? and 2) To what extent do invasive plants alter aquatic ecosystems by reducing native biodiversity and leaving systems more susceptible to invasions by additional species? By filling in some of these critical knowledge gaps, my research will help managers to prevent biological invasions by prioritizing sites where prevention strategies should be focused, either because those sites are particularly vulnerable to invasions, or are particularly likely to experience extensive deleterious effects following invasions. Prevention is a far more successful strategy than the removal of established invasives, and my research will therefore provide substantial economic and social benefits to Canada.**