Nutrient Effects on a Detritus-based Stream Ecosystem

营养对碎屑河流生态系统的影响营养浓度的增加威胁着世界范围内的水生生态系统。人类和动物的污水以及农田的化肥径流中的营养物质，主要是氮和磷，在许多湖泊和溪流中浓度很高。 水体中藻类的数量通常会随着营养供应的增加而大幅增加，并极大地改变了食物网的其余部分。 然而，许多水生食物网的能量来源是死亡的植物（碎屑）以及相关的细菌和真菌，而不是藻类。 这项研究将确定增加养分供应的影响，在森林流碎屑为基础的食物网。 研究人员将测试营养添加是否会增加微生物的产量，从而增加溪流消费者的生长。 他们还将测试微生物是否以导致更高消费者食物减少的速度消耗碎屑，从而破坏食物网的稳定。 这项工作的结果将有助于预测其他基于碎屑的生态系统如何应对人类对营养供应的改变。

Abstract98-06610RosemondNutrient effects on a detritus-based stream ecosystemIncreased nutrient concentrations threaten aquatic ecosystems worldwide. Nutrients, primarily nitrogen and phosphorus, from human and animal sewage and fertilizer runoff from farmland, are found in high concentrations in many lakes and streams. The amount of algae in the water body typically increases greatly in response to increased nutrient supply and dramatically alters the rest of the food web. However, the energy source of many aquatic food webs is dead plants (detritus) with associated bacteria and fungi, not algae. This study will determine the effects of increased nutrient supply on a detrital-based food web in a forested stream. The investigators will test whether nutrient addition increases microbial production and subsequently increases growth of stream consumers. They will also test whether microbes deplete detritus at rates that result in less food for higher consumers, thereby destabilizing the food web. The results of this work will aid in predicting how other detrital-based ecosystems respond to and are altered by human modification of nutrient supply.