Quantifying Nutrient and Energy Flows in Aquatic Food Webs

生态系统正在因气候变化而改变。 劳伦特五大湖的变暖速度在世界上排名第二，必须开发新的模型和新的技术，使我们能够预测和衡量气候变化对水生生态系统的影响。 我们将通过进一步开发非稳态生物累积模型以及验证使用持久性有机污染物和汞作为环境示踪剂来量化水生食物网中的能量和营养流来应对这一挑战。 这两个研究计划是互动和相互依存的，因为非稳态模型有相对较高的数据要求，需要有关生长率，觅食策略和季节性代谢过程，调节污染物的吸收和消除过程的信息。 我们提出了四个项目。 首先，我们将调查化学积累动力学湖鳟鱼和鲑鱼在休伦湖的食物网，这是在崩溃的状态。我们将使用非稳态模型的方法来估计能量需求的鱼，并衡量这些鱼的营养循环和休伦湖的命运的相对贡献。据预测，湖鳟提供了一个关键的作用，在营养循环，而鲑鱼主要是一个营养损失的载体。 湖鳟鱼种群的下降与鲑鱼的放养相结合，建议在这个系统中的食物网崩溃作出了贡献。 第二项研究旨在扩大持久性有机污染物非稳态模型的校准范围，将汞作为一种环境示踪剂纳入其中。 汞的同化效率比持久性有机污染物高得多，但人们对鱼类从食物中吸收汞的调节机制知之甚少。 我们将研究蛋白质动力学/动力学的作用，以更深入地了解是什么使汞在鱼类中成为超级累积者。 第三，鱼类消费率和体重之间存在很强的关系，遵循四分之三幂定律。 我们将使用持久性有机污染物和汞作为鱼类消费率的就地测量，以研究同一湖泊中温水和冷水物种消费率的差异。 我们预测消耗率和质量之间的斜率将是相似的，符合四分之三幂定律，但截距将显着不同。最后，根据最初的稳定状态生物累积模型的预测制定的鱼类消费准则假定个体差异很小。 这一假设已被许多研究推翻，需要更好地了解过程中，调节污染物负荷的高个体差异。 我们建议研究营养水平、生长率和觅食策略作为世界第二大商业渔业所在地西伊利湖鱼类种群污染物个体变异性调节因子的相对重要性。

Ecological systems are being modified by climate change. The Laurentian Great Lakes have the second fastest rates of warming in the world, and it is essential to develop new models and novel techniques that allow us to predict and measure the effects of climate change on aquatic ecosystems. We will address this challenge with the further development of non-steady state bioaccumulation models as well as the verification of the use of persistent organic pollutants (POPs) and mercury as environmental tracers to quantify energy and nutrient flow in aquatic food webs. These two research initiatives are interactive and interdependent in that non-steady state models have relatively high data requirements, needing information on growth rates, foraging strategies and seasonal metabolic processes that regulate contaminant uptake and elimination processes. We propose four projects. First we will investigate chemical accumulation dynamics in lake trout and salmon in the food web of Lake Huron which is in a state of collapse. We will use the non-steady state model approach to estimate energy requirements of the fish and measure the relative contribution of these fish to nutrient recycling and fate in Lake Huron. It is predicted that lake trout provide a critical role in nutrient recycling whereas salmon are primarily a nutrient loss vector. The decline in lake trout populations combined with the stocking of salmon is suggested to have contributed to the food web collapse in this system. The second study aims to expand the calibration of the non-steady state model from POPs to include mercury as an environmental tracer. Mercury exhibits a much higher assimilation efficiency than POPs, but little is known what regulates the assimilation of Hg from food in fish. We will examine the role of protein dynamics/kinetics to gain more insight as to what makes Hg a super-accumulator in fish. Thirdly, there is a strong relationship between fish consumption rates and body mass which follows the Three Quarter Power Law. We will use both POPs and Hg as insitu measures of fish consumption rates to study differences in consumption rates of warm and cold water species occupying the same lakes. We predict the slope between consumption rate and mass will be similar, fitting the three quarter power law, but the intercepts will be significantly different. Lastly, fish consumption guidelines based on predictions of original steady state bioaccumulation models assume there is little individual variability. This assumption has been disproved by many studies, necessitating a better understanding of processes that regulate the high individual variability in contaminant burdens. We propose to examine the relative importance of trophic level, growth rates and foraging strategies as regulators of individual variability of contaminant in fish populations in Western Lake Erie, home to the second largest commercial fisheries in the world.