Can consumer stoichiometric regulation control nutrient spiraling in streams?
Can consumer stoichiometric regulation control nutrient spiraling in streams?
复制标题
消费者化学计量调节可以控制溪流中养分的螺旋上升吗？
DOI：
10.1899/08-099.1
复制
发表时间：
2009
影响因子：
2.7
通讯作者：
C. Kazanci
中科院分区：
文献类型：
--
作者：
G. Small;A. Helton;C. Kazanci
摘要稳态生物通过保留限制和消除过量的营养物质来调节其元素组成。我们认为，这种类型的消费者的稳态调节可能会解耦的下游运动的限制和非限制性的营养物质流。为了说明消费者对营养螺旋的影响，我们开发了一个纵向模型流营养动态，明确结合化学计量和回收。首先，我们模拟了N-和P-示踪剂添加实验中的P-有限的流与粒子跟踪算法，使我们能够遵循的N和P原子在模型生态系统中的路径。然后，我们改变了生物量，N：P比，和消费者的化学计量调节强度，以量化这些参数如何影响建模螺旋指标。粒子跟踪模拟表明，营养素原子完成螺旋的平均时间随着每个螺旋中进入消费者隔室的原子比例而增加，而这又随着消费者生物量的增加而增加。增加消费者的N：P比，加剧消费者的化学计量不平衡与食物资源改变了营养物质在食物网中的停留时间，通过增加下游的速度的非限制性营养物质和延迟下游运输的限制性营养物质。减少消费者的化学计量调节的强度抑制了所观察到的影响，增加消费者的生物量和N：P比营养螺旋。我们的模型结果表明，消费者有可能影响流营养动态通过差异排泄的限制和非限制性的营养物质，但只有在相对较高的生物量。河流生态地球化学主要集中在控制溶解营养物质的吸收的因素，但了解这些营养物质是如何保留和回收，一旦他们进入流食物网将导致更完整的理解在流中的营养动态。
Abstract Homeostatic organisms regulate their elemental composition by retaining nutrients that are limiting and eliminating those in excess. We argue that this type of homeostatic regulation by consumers might decouple the downstream movement of limiting and nonlimiting nutrients in streams. To illustrate the influence of consumers on nutrient spiraling, we developed a longitudinal model of stream nutrient dynamics that explicitly incorporates stoichiometry and recycling. First, we simulated N- and P-tracer addition experiments in a P-limited stream with a particle-tracking algorithm that allowed us to follow the pathways of N and P atoms in the model ecosystem. Then, we varied the biomass, N:P ratio, and strength of stoichiometric regulation of consumers to quantify how these parameters affected modeled spiraling metrics. The particle-tracking simulation showed that the average time for a nutrient atom to complete a spiral increased with the fraction of atoms that entered the consumer compartment in each spiral, which in turn, increased with increasing consumer biomass. Increasing the consumer N:P ratio to exacerbate consumer stoichiometric imbalance with food resources changed the residence times of nutrients in the food web by increasing the downstream velocity of the nonlimiting nutrient and delaying downstream transport of the limiting nutrient. Decreasing the strength of stoichiometric regulation of consumers dampened the observed effects of increased consumer biomass and N:P ratios on nutrient spiraling. Our model results illustrate that consumers have the potential to influence stream nutrient dynamics through differential excretion of limiting and nonlimiting nutrients, but only at relatively high biomass. Stream biogeochemistry has largely focused on factors controlling the uptake of dissolved nutrients, but understanding how these nutrients are retained and recycled once they enter the stream food web will lead to a more complete understanding of nutrient dynamics in streams.