Ecology of Stream Nutrient Pulses

人为破坏营养循环大大增加了河流生态系统的养分供应，导致全球富营养化危机，威胁到河流生态系统为人类社会提供的许多服务。对于许多河流，特别是农业生态系统中的河流，在短时间的水文事件中，大量的营养物质被输送到河流中。然而，脉动养分负荷对河流的生态影响尚未得到很好的描述。我的研究项目将使用一系列的中生态实验来：1)量化脉冲营养添加对藻类多样性和生物量的影响；2)确定调节脉冲营养添加引起的群落变化幅度和性质的环境因子（即流量、光照和环境养分有效性）。上述中生态系统实验，加上伊利湖和温尼伯流域河流的季节性磷添加实验，将用于确定藻类群落的多样性和生物量变化是否调节相关生态系统过程和食物网结构的速率。已确定的群落-生态系统过程联系的稳定性将通过两次单独的实地调查在空间和时间上确定。结合起来，这项研究将解决知识链上的多个空白，将景观模式与藻类动力学和最终的河流生态系统过程联系起来。这些数据还将提供必要的基础信息，以生成工具，加强河流监测程序，并设定营养目标，可用于保护和恢复河流免受河流营养脉冲的损害。我的研究计划将通过应用所描述的将环境特性与藻类群落和生态系统过程联系起来的关系来启动这一过程，以生成和测试可扩展的模型，预测脉冲营养负荷的生态后果。这些模型将允许在预测的气候和土地利用变化情景下，预测可能影响有价值的生态系统服务（娱乐和水净化）的藻类多样性和营养吸收的河段尺度变化。我的实验室将继续与政府的决策者合作，将这些数据和工具纳入政策，从而加强对加拿大和世界各地受富营养化威胁的河流生态系统的管理。这项工作将与4名博士生、4名硕士生、5名本科生和多名本科生研究助理合作。这些学生将在水生科学研究的各个方面接受广泛的培训，为他们在学术、政府和私营部门的成功职业生涯提供沟通、领导和技术技能。

Anthropic disruption of nutrient cycles has dramatically increased nutrient availability to stream ecosystems leading to a global eutrophication crisis threatening the many services stream ecosystems provide to human society. For many streams, especially those in agro-ecosystems, large quantities of nutrients are delivered to streams during short-duration hydrologic events. However, the ecological consequences of pulse nutrient loadings to streams are not well described. My research program will use a series of mesocosm experiments to: 1) quantify effects of pulse nutrient additions on algal diversity and biomass, and; 2) identify environmental factors (i.e., flow, light and ambient nutrient availability) regulating the magnitude and nature of community change caused by pulse nutrient additions. The afore-mentioned mesocosm experiments, coupled with seasonal phosphorus addition experiments to streams in the basins of Lakes Erie and Winnipeg, will be used to determine if diversity and biomass changes in algal communities mediate rates of associated ecosystem processes and food web structure. Stability of the identified community-ecosystem process linkages will be determined across space and time using two separate field surveys. Combined, this research will address multiple gaps along the knowledge chain linking landscape patterns to reach-scale nutrient delivery to algal dynamics and, ultimately, stream ecosystem processes. These data will also provide foundational information needed to generate tools that can enhance stream monitoring programs and set nutrient targets that can be used to protect and restore streams from impairment by stream nutrient pulses. My research program will initiate this process by applying the described relationships linking environmental properties to algal communities and ecosystem processes to generate and test scalable models predicting ecological consequences of pulse nutrient loadings. These models will allow prediction of reach-scale changes in algal diversity and nutrient uptake that can impact valued ecosystem services (recreation and water purification) under forecasted climate and land use change scenarios. My lab will continue to work with decision-makers in government to incorporate these data and tools into policy thereby enhancing management of stream ecosystems threaten by eutrophication within Canada and around the world. The proposed work will engage collaboration with 4 PhD students, 4 MSc students, 5 undergraduate thesis students and multiple undergraduate research assistants. These students will receive extensive training in all aspects of research within the aquatic sciences providing them the communication, leadership and technical skills for successful careers in academic, government and private sectors.