Effective management of wild animals requires understanding how predation and harvest alter the composition of populations. These top‐down processes can alter consumer body size and behavior and thus should also have consequences for bottom‐up processes because (1) body size is a critical determinant of the amount of nutrients excreted and (2) variation in foraging behavior, which is strongly influenced by predation, can determine the amount and spatial distribution of nutrients. Changes to either are known to affect ecosystem‐scale nutrient dynamics, but the consequences of these dynamics on ecosystem processes are poorly understood. We used an individual‐based model of an artificial reef (AR) and reef fish in a subtropical seagrass bed to test how fish body size can interact with variation in foraging behavior at the population and individual levels to affect seagrass production in a nutrient‐limited system. Seagrass production dynamics can be driven by both belowground (BGPP) and aboveground primary production (AGPP); thus, we quantified ecosystem‐scale production via these different mechanistic pathways. We found that (1) populations of small fish generated greater total primary production (TLPP = BGPP + AGPP) than large fish, (2) fish that foraged more increased TLPP more than those that spent time sheltering on ARs, and (3) small fish that foraged more led to greatest increases in TLPP. The mechanism by which this occurred was primarily through increased BGPP, highlighting the importance of cryptic belowground dynamics in seagrass ecosystems. Populations of extremely bold individuals (i.e., foraged significantly more) slightly increased TLPP but strongly affected the distribution of production, whereby bold individuals increased BGPP, while populations of shy individuals increased AGPP. Taken together, these results provide a link between consumer body size, variation in consumer behavior, and primary production—which, in turn, will support secondary production for fisheries. Our study suggests that human‐induced changes—such as fishing—that alter consumer body size and behavior will fundamentally change ecosystem‐scale production dynamics. Understanding the ecosystem effects of harvest on consumer populations is critical for ecosystem‐based management, including the development of ARs for fisheries.

中文翻译：

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更小、更大胆的鱼增强了海草床人工鱼礁周围生态系统规模的初级生产


有效管理野生动物需要了解捕食和收获如何改变种群构成。这些自上而下的过程可以改变消费者的体型和行为，因此也应该对自下而上的过程产生影响，因为 （1） 体型是排泄营养物质量的关键决定因素，以及 （2） 受捕食强烈影响的觅食行为的变化可以决定营养物质的数量和空间分布。众所周知，对任何一种变化都会影响生态系统规模的营养动态，但这些动态对生态系统过程的影响知之甚少。我们使用了亚热带海草床中人工鱼礁 （AR） 和珊瑚鱼的基于个体的模型来测试鱼的体型如何与种群和个体水平的觅食行为变化相互作用，从而影响营养有限系统中的海草生产。海草生产动态可以由地下 （BGPP） 和地上初级生产 （AGPP） 驱动;因此，我们通过这些不同的机制途径量化了生态系统规模的生产。我们发现 （1） 小鱼种群比大鱼产生更大的总初级生产 （TLPP = BGPP + AGPP），（2） 觅食更多的鱼比那些花时间躲在 AR 上的鱼增加的 TLPP 更多，以及 （3） 觅食更多的小鱼导致 TLPP 的最大增加。发生这种情况的机制主要是通过增加 BGPP，这凸显了神秘的地下动态在海草生态系统中的重要性。极其大胆的个体种群（即，觅食明显更多）略微增加了 TLPP，但强烈影响了生产分布，其中大胆的个体增加了 BGPP，而害羞的个体种群增加了 AGPP。综上所述，这些结果提供了消费者体型、消费者行为变化和初级生产之间的联系，这反过来又将支持渔业的二次生产。我们的研究表明，改变消费者体型和行为的人为变化（例如捕鱼）将从根本上改变生态系统规模的生产动态。了解捕捞对消费者群体的生态系统影响对于基于生态系统的管理至关重要，包括为渔业开发 AR。