DISSERTATION RESEARCH: Highly unsaturated fatty acid transfer from aquatic to terrestrial food webs

溪流依靠来自陆地景观的营养来为生活在其中的植物和动物的生产提供燃料。反过来，河流生物，如新兴的水生昆虫，为陆地捕食者提供能量和营养，包括河边的鸟类。涌现的溪流昆虫可能是河边捕食者特别重要的食物来源。过去大多数关于河流和陆地景观之间营养物质运动的研究都是在相对未受干扰的森林中进行的。然而，与藻类和溪流昆虫丰富的农业景观中高产的溪流相比，在森林溪流中，溪流衍生的营养物质对河边捕食者的贡献实际上可能没有那么重要。本研究将考察以下因素的影响：1)食物的可得性和质量对一种代表性的河滨鸟类——东菲比（Sayornis Phoebe）生长速度的影响；2)农业用地与林地用地对东菲比雏鸟淡水和陆地食物资源的可得性和质量的影响。研究人员将通过分享结果摘要与当地环境管理者和土地所有者合作，并且在可公开访问的研究地点，将使用信息标志来解释研究。研究人员将与当地一家儿童科学博物馆合作，根据研究主题编写演示文稿，并将继续指导未被充分代表的少数民族本科生。食物质量和数量的影响将通过在实验室环境中饲养菲比雏鸡生长最快的时期（第4-9天）来测量。雏鸡将以二对二的设计方式饲喂数量（高热量或低热量）和质量（高不饱和脂肪酸或低不饱和脂肪酸）不同的饲粮。菲比雏鸡体重、头长和跗骨长度将每天测量。为了研究自然环境下土地利用对食品质量和质量的影响，将把鸡的生长测量与脂肪酸组成分析相结合，以量化各试验点的食品质量。phoebe的组织及其陆生和水生食物的稳定同位素分析将用于重建phoebe获得食物资源的地方。研究人员希望农业场所能够为菲比提供更高数量和质量的食物，从而加快菲比的生长速度。将对phoebe的组织及其陆生和水生食物进行化合物特异性稳定同位素分析，以确定土地利用如何影响phoebe获得高度不饱和脂肪酸的地方。研究人员期望农业场所的疏水生物获得由水生初级生产者合成的高度不饱和脂肪酸，而森林场所的疏水生物获得由陆地初级生产者合成的分子前体延长的高度不饱和脂肪酸。

Streams depend upon nutrients from terrestrial landscapes to fuel the production of the plants and animals living in them. Reciprocally, stream organisms such as emerging aquatic insects provide energy and nutrients to terrestrial predators, including streamside birds. Emergent stream insects are likely an especially important food source for streamside predators. Most past studies on nutrient movement between streams and terrestrial landscapes have been conducted in relatively undisturbed forests. However, the contribution of stream-derived nutrients to streamside predators may actually be less important in forested streams than in highly productive streams in agricultural landscapes where algae and stream insects are abundant. This research will examine effects of: 1) food availability and quality on the growth rates of a representative streamside bird, the Eastern Phoebe (Sayornis phoebe), and 2) agricultural versus forested land use on the availability and quality of freshwater and terrestrial food resources for Eastern Phoebe chicks. The researchers will collaborate with local environmental managers and landowners by sharing summaries of results, and at publicly accessible study sites, informational signs will be used to explain the research. The researchers will work with a local children's science museum to develop presentations based on the research themes, and will continue to mentor underrepresented minority undergraduates.Effects of food quality and quantity will be measured by raising phoebe chicks during their most rapid period of growth (days 4-9) in lab settings. Chicks will be fed diets that vary in quantity (high or low calorie) and quality (high or low highly unsaturated fatty acids) in a two by two design. Phoebe chick weight, head length, and tarsus length will be measured daily. To examine the effects of land use on food quality and quality in a natural setting, chick growth measurements will be coupled to fatty acid composition analyses to quantify food quality across sites. Stable isotope analyses of phoebe tissues and their terrestrial and aquatic dietary items will be used to reconstruct where phoebes obtain food resources. The researchers expect agricultural sites to provide phoebes with both higher food quantity and quality resulting in faster phoebe growth rates. Compound-specific stable isotope analyses of phoebe tissues and their terrestrial and aquatic dietary items will be performed to determine how land use affects where phoebes obtain highly unsaturated fatty acids. The researchers expect phoebes at agricultural sites to obtain highly unsaturated fatty acids synthesized by aquatic primary producers and phoebes at forested sites to obtain highly unsaturated fatty acids elongated from their molecular precursors synthesized by terrestrial primary producers.