Effects of multiple stressors on littoral habitat and lake ecosystems

湖泊和河流为我们提供了许多生态服务，从饮用水到娱乐机会。它们也被认为是地球上受人类影响最大的生态系统之一。然而，长期（几十年或更长时间）的环境数据很少能作为评价人类引起的生态系统变化的基准，因此需要古生态数据来评估人类对水生生态系统的干扰。湖泊的近岸沿岸地带往往是湖泊形成最早、受影响最严重的地区。因此，将具有生态影响和多样性的近岸沿岸环境的响应纳入我们对水生生态系统变化的理解是很重要的。在温带湖泊中，近岸岸带的一个决定性特征是淹没的植物床（大型植物）。大型植物床是湖泊中生物多样性最丰富的区域之一，是过多营养物质的汇，是包括顶级捕食者在内的许多动物的重要栖息地，并增强生态系统的恢复能力。我们对人类如何改变大型植物床的理解大部分来自对欧洲的浅水（最大深度<5米）、高营养丰富的湖泊的研究，这些湖泊的大型植物生物量几乎消失了。由于过去的研究主要集中在这些浅层、高营养丰富的系统上，它们的结果不能直接转移到加拿大常见的更深层次、分层和营养更有限的湖泊生态系统上。因此，我们需要新的研究来提高我们对人类对加拿大湖泊大型植物床的影响的认识。我的研究将评估从床内到全湖范围内的大型植物对常见环境压力（气候变化、土地利用变化、入侵物种和污染）的响应，并确定大型植物床的变化对整个湖泊生态系统的生态恢复能力有什么影响。这项研究将促进我们对人类活动如何改变近岸沿岸环境的理解，以及这些变化如何影响加拿大常见的更深层次、分层、营养有限的湖泊的整个湖泊生态系统。这项研究将有助于环境管理者和湖泊协会在不断变化的世界中更好地保护和恢复加拿大的淡水资源。

Lakes and rivers provide us many ecological services, from drinking water to recreation opportunities. They are also considered among the most human-impacted ecosystems on the planet. Long-term (multi-decadal or longer) environmental data, however, are rarely available as a benchmark to evaluate human-induced ecosystem changes and therefore paleoecological data are needed to assess human disturbance to aquatic ecosystems. The near-shore littoral zone of lakes is often the earliest and most severely impacted region of a lake. Because of this, it is important that we integrate the response of the ecologically influential and diverse near-shore littoral environment into our understanding of aquatic ecosystem change. In temperate lakes, one of the defining features of the near-shore littoral zone are submerged plant beds (macrophytes). Macrophyte beds are among the most biodiverse areas in lakes, are sinks for excessive nutrients, serve as important habitat for numerous animals including top predators, and enhance ecosystem resilience. Much of our understanding of how humans alter macrophyte beds comes from studies on shallow (max depth <5m), hyper-nutrient rich, lakes in Europe where macrophyte biomass has all but disappeared. Because past studies have focused primarily on these shallow, hyper-nutrient rich systems their results are not directly transferable to the deeper, stratified, and more nutrient-limited lake ecosystems common in Canada. Therefore, we require new research to advance our knowledge of human-impacts on macrophyte beds in Canadian lakes. My research will evaluate macrophyte response to common environmental stressors (climate change, land-use change, invasive species, and pollution) from the within-bed to the whole-lake scale and determine what impact, if any, changes in the macrophyte beds have on the ecological resilience of the whole-lake ecosystem. This research will advance our understanding of how human activities are altering the near-shore littoral environment and how these changes impact the entire lake ecosystem in deeper, stratified, nutrient-limited lakes common in Canada. This research will help environmental managers and lake associations better conserve and restore Canada’s freshwater resources in a changing world.