Ecology of Stream Nutrient Pulses

人类对营养循环的破坏极大地增加了河流生态系统的养分可获得性，导致了全球富营养化危机，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，在短期水文事件期间，大量营养物质被输送到溪流。然而，脉冲营养负荷对溪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中观实验：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、光照和环境养分有效性)，调节脉冲营养添加引起的群落变化的大小和性质。上述中游实验，加上伊利湖和温尼伯湖流域溪流的季节性磷添加实验，将被用来确定藻类群落的多样性和生物量变化是否会调节相关的生态系统过程和食物网络结构的速率。确定的社区-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缺口，将景观模式与藻类动态以及最终的河流生态系统过程联系起来，以达到规模的营养输送。这些数据还将提供产生工具所需的基本信息，这些工具可以加强溪流监测计划并设定营养目标，这些目标可用于保护和恢复溪流免受溪流营养脉冲的损害。我的研究计划将通过应用所描述的将环境属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。这些模型将能够在预测的气候和土地利用变化情景下预测河流范围内藻类多样性和养分吸收的变化，这些变化可能会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。这项拟议的工作将与4名博士生、4名硕士学生、5名本科生论文学生和多名本科生研究助理进行合作。这些学生将在水产科学的所有研究方面接受广泛的培训，为他们提供在学术、政府和私营部门成功职业生涯所需的沟通、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.