REU: The N:P Stoichiometry of Nutrient Release by Daphnia

水生食草动物利用的食物基础， 碳氮磷比例 动物调整它们对氮的吸收 和磷，使供应量少的元素被吸收得多 有效地 这一提议的假设是， 放牧化学计量、养分同化和释放 预测食草动物会使营养限制模式产生分歧， 使其藻类猎物摆脱N和P的共同限制， 通过N或P限制。质量平衡技术 将允许N和P的摄入、同化和再释放， 同时测量水蚤面临的不同 不同C：N：P的藻类的浓度。 组织C：N：P的水蚤已经饲养的藻类 还将执行不同的C：N：P。 该项目将 确定N和P的再循环效率， 养分浓度比与供给比有关， 通常假设。 此外，它还将探讨 水生生态系统中的食物网动态， 需要一个主要水生生物的N和P生理学的基本数据， 有机体

Aquatic herbivores utilize a food base that can vary widely in its C:N:P ratio. The animals adjust their assimilation of N and P so that the element in shorter supply is assimilated more efficiently. The hypothesis of this proposal on the stoichiometry of grazing, assimilation and release of nutrient predicts that grazers make nutrient limitation patterns diverge, leading their algal prey away from co-limitation by N and P and toward limitation by either N or P. A Mass balance technique will allow ingestion, assimilation and re-release of N and P to be measured simultaneously for Daphnia faced with different concentrations of algae of differing C:N:P. Determinations of tissue C:N:P of Daphnia that have been reared on algae of different C:N:P will also be performed. This project will determine the recycling efficiencies of N and P and whether nutrient concentration ratios are related to supply ratios, as is commonly assumed. Also, it will explore fundamental consequences of food web dynamics in aquatic ecosystems while providing badly needed basic data on the N and P physiology of a major aquatic organism.