Odum School of Ecology, University of Georgia, Athens, Georgia 30602, USA.
Ecology. 2013 Feb;94(2):521-9. doi: 10.1890/12-1122.1.
Consumer-mediated nutrient supply is increasingly recognized as an important functional process in many ecosystems. Yet, experimentation at relevant spatial and temporal scales is needed to fully integrate this bottom-up pathway into ecosystem models. Artificial reefs provide a unique approach to explore the importance of consumer nutrient supply for ecosystem function in coastal marine environments. We used bioenergetics models to estimate community-level nutrient supply by fishes, and relevant measures of primary production, to test the hypothesis that consumers, via excretion of nutrients, can enhance primary production and alter nutrient limitation regimes for two dominant primary producer groups (seagrass and benthic microalgae) around artificial reefs. Both producer groups demonstrated marked increases in production, as well as shifts in nutrient limitation regimes, with increased fish-derived nutrient supply. Individuals from the two dominant functional feeding groups (herbivores and mesopredators) supplied nutrients at divergent rates and ratios from one another, underscoring the importance of community structure for nutrient supply to primary producers. Our findings demonstrate that consumers, through an underappreciated bottom-up mechanism in marine environments, can alter nutrient limitation regimes and primary production, thereby fundamentally affecting the way these ecosystems function.
消费者介导的养分供应在许多生态系统中越来越被认为是一个重要的功能过程。然而，需要在相关的时空尺度上进行实验，才能将这种自下而上的途径完全纳入生态系统模型。人工礁石为探索消费者养分供应对沿海海洋环境中生态系统功能的重要性提供了一种独特的方法。我们使用生物能量学模型来估计鱼类的群落水平养分供应，并采用相关的初级生产力措施，以检验消费者通过排泄养分来增强初级生产力并改变两种主要初级生产者群体（海草和底栖微藻）的养分限制制度的假设。这两个生产者群体的产量都显著增加，同时养分限制制度也发生了变化，这与鱼类提供的养分供应增加有关。来自两个主要功能摄食群（草食动物和中型捕食者）的个体彼此之间以不同的速度和比例提供养分，这突显了群落结构对初级生产者养分供应的重要性。我们的研究结果表明，消费者通过海洋环境中一种被低估的自下而上的机制，可以改变养分限制制度和初级生产力，从而从根本上影响这些生态系统的功能方式。
