Paleoenvironmental investigation of an emerging stressor to Canadian salmon rivers

长期的观点有助于区分自然生态系统的可变性和人类的影响，并认识到环境变化的速度和程度。古湖沼学是一门利用沉积物记录中保存的物理、化学和生物信息来追踪长期（通常是数十年到数千年）环境变化的科学。我的研究计划结合了古湖沼学方法和现代生态采样，以更好地了解淡水生态系统如何应对自然过程和人为造成的压力。这种跨学科的方法可以成为一种强有力的工具，用于确定因果关系，建立基线生态系统条件，并根据人类活动的影响制定现实的恢复目标。我提出的研究计划的目的是了解的原因和影响的滋扰增长（开花）的底部居住的鱼，Didymosphenia geminata（Didymo），在偏远的，原始的鲑鱼河流在西部（温哥华岛，公元前）和东部（加斯佩地区的QC和北方NB）地区的加拿大。通过研究目前正在经历令人讨厌的Didymo水华的地区的沉积物记录中保存的信息，我们将能够评估导致水华在这些生态系统中形成和扩散的长期环境驱动因素。这种时间的观点将使我们能够确定气候变化，全球大气污染的营养物质或历史上的土地利用方式是否会影响Didymo水华发生的淡水。这些广泛的压力被认为是创造条件有利于水华的形成和持久性，虽然详细的评估还没有发生的日期。我们的方法可以识别最近的Didymo开花是否是前所未有的，在过去的~2000年或是否发生在遥远的过去。我们还将通过对无脊椎动物、藻类和幼年大西洋鲑鱼进行采样，对加拿大东部两条河流的河流栖息地进行现代生态研究。这种方法将有助于我们了解Didymo水华如何影响河流栖息地，并最终影响幼鲑的饮食。在网站和没有Didymo开花，我们将调查的食物网结构和猎物的数量和质量的差异，少年鲑鱼消费。更好地了解Didymo水华的原因和影响将为政府和生态系统管理人员提供科学知识，以帮助管理这些最近经历底栖藻类水华的标志性加拿大鲑鱼河流。

A long-term perspective is useful to distinguish natural ecosystem variability from human impacts, and to recognize the rates and magnitude of environmental change. Paleolimnology is the science that uses the physical, chemical, and biological information preserved in sediment records to track environmental changes over long periods of time, often decades to millennia. My research program combines a paleolimnological approach and modern ecological sampling to better understand how freshwater ecosystems respond to natural processes and human-caused stressors. This interdisciplinary approach can be a powerful tool to determine cause-and-effect, establish baseline ecosystem conditions, and set realistic recovery goals following the impacts from human activities. My proposed research program aims to understand the causes and effects of nuisance growths (blooms) of the bottom-dwelling alga, Didymosphenia geminata (Didymo), in remote, pristine salmon rivers in western (Vancouver Island, BC) and eastern (Gaspe region of QC and northern NB) regions of Canada. By studying the information preserved in sediment records within regions currently experiencing nuisance Didymo blooms we will be able to assess the long-term environmental drivers that cause blooms to form and proliferate across these ecosystems. This temporal perspective will allow us to determine whether climatic change, nutrients from global atmospheric pollution, or historic land-use practices are impacting freshwaters where Didymo blooms occur. These widespread stressors are believed to create conditions favorable to bloom formation and persistence, although detailed evaluations have not occurred to date. Our approach can recognize whether recent Didymo blooms are unprecedented over the last ~2000 years or whether blooms have occurred in the distant past. We will also conduct a modern ecological study of river habitats in two eastern Canadian rivers by sampling invertebrates, algae, and juvenile Atlantic salmon. This approach will help us to understand how Didymo blooms affect river habitat and ultimately impact the diet of juvenile salmon. At sites with and without Didymo blooms, we will investigate differences in food web structure and the quantity and quality of prey that juvenile salmon consume. A greater understanding of both the causes and effects of Didymo blooms will provide government and ecosystem managers with scientific knowledge to aid in the management of these iconic Canadian salmon rivers experiencing recent benthic algal blooms.