Ecology of Stream Nutrient Pulses

人类活动对河流生态系统养分循环的破坏极大地增加了河流生态系统的养分供应，导致全球性的富营养化危机，威胁着河流生态系统为人类社会提供的许多服务。对于许多溪流，特别是农业生态系统中的溪流，在短时间的水文事件期间，大量的营养物质被输送到溪流。然而，脉冲营养负荷流的生态后果没有得到很好的描述。我的研究计划将使用一系列的围隔实验：1）量化脉冲营养添加对藻类多样性和生物量的影响，2）确定环境因素（即，流量、光照和环境养分的有效性）调节由脉冲养分添加引起的群落变化的幅度和性质。上述围隔实验，再加上季节性磷添加实验流在伊利湖和温尼伯的盆地，将被用来确定藻类群落的多样性和生物量的变化介导相关的生态系统过程和食物网结构的速度。将通过两次单独的实地调查，确定已确定的社区-生态系统进程联系在空间和时间上的稳定性。结合起来，这项研究将解决多个差距沿着知识链连接景观格局达到规模的营养输送藻类动态，并最终流生态系统过程。这些数据还将提供生成工具所需的基础信息，这些工具可以增强河流监测计划，并设定可用于保护和恢复河流免受河流营养脉冲损害的营养目标。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，以生成和测试预测脉冲营养负荷的生态后果的可扩展模型。这些模型将能够预测藻类多样性和养分吸收的可达范围变化，在预测的气候和土地利用变化情景下，这些变化可能影响有价值的生态系统服务（娱乐和水净化）。我的实验室将继续与政府决策者合作，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。拟议的工作将与4名博士生，4名硕士生，5名本科论文学生和多名本科研究助理合作。这些学生将在水产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.