Collaborative research: Exploring the generality of light, nutrient and predator constraints on food chain efficiency

这项研究将研究阳光、营养物质和捕食者如何影响食物网中能量流动的效率。阳光和营养物质影响藻类的化学成分，包括碳、氮、磷以及必需脂肪酸(EFAs)的数量和比例。此外，光和营养物质可以决定哪些藻类物种存在，以及它们对草食动物的消化能力。碳：营养比、EFAs和藻类的消化阻力的变化可以决定食草动物的产量，但关于这些影响如何传播到食物链顶端的动物，如鱼类和其他食肉动物，人们知之甚少。研究人员将进行三个大规模的实验，以调查光线、营养物质、食肉动物种类、食物网状结构和营养比例对食物链效率的影响。他们还将开发下一代化学计量学显式计算机模型，这些模型将提供对实验结果的机械性理解，并扩大研究范围。该项目将为参与水质保护和渔业管理的决策者提供关键信息。例如，渔业产量取决于食物链效率，特别是转化为人类捕捞的鱼类或贝类物种的藻类产量的比例；由于食草动物在过度营养丰富后低效利用植物生产造成的富营养化；深水和沉积物中的碳储存(减少大气中的温室气体)与未在中上层食物链消耗的能源有关；每个营养级的污染物浓度受到食物链能量流动的影响。此外，许多全球范围的环境问题，如富营养化和气候变化，改变了光和营养的供应，并可能调节食物链的效率。此外，该项目将为本科生和研究生提供大量机会，他们将积极参与研究的各个方面。

This research will examine how the efficiency of energy flow through food webs is affected by sunlight, nutrients, and predators. Sunlight and nutrients affect the chemical composition of algae, including the amounts and ratios of carbon, nitrogen and phosphorus as well as essential fatty acids (EFAs). In addition, light and nutrients can determine which algal species are present, and their digestibility for herbivores. Variation in carbon:nutrient ratios, EFAs, and digestion resistance of algae can determine the production of herbivores, but little is known about how these effects propagate to animals at the top of the food chain, e.g., fish and other carnivores. The investigators will conduct three large-scale experiments to investigate effects of light, nutrients, carnivore species, food web structure, and nutrient ratios on food chain efficiency. They will also develop next-generation, stoichiometrically-explicit computer models which will provide mechanistic understanding of the experimental results, and expand the scope of the research.This project will provide critical information for decision-makers involved in water quality protection and fisheries management. For example, fisheries yields depend on food chain efficiency, specifically the proportion of algae production that is converted into fish or shellfish species harvested by humans; eutrophication results from the inefficient use of plant production by herbivores after excessive nutrient enrichment; carbon storage in deep waters and sediments (which reduces greenhouse gases in the atmosphere) is related to energy that is not consumed in pelagic food chains; and the concentrations of contaminants at each trophic level is affected by energy flow through food chains. In addition, many global-scale environmental problems, such as eutrophication and climate change, alter the supplies of light and nutrients, and can mediate food chain efficiency. In addition the project will provide numerous opportunities for undergraduate and graduate students, who will be actively engaged in all aspects of the research.